summaryrefslogtreecommitdiff
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<h1 class="settitle" align="center">GnuTLS 3.4.8</h1>


















<a name="SEC_Contents"></a>
<h2 class="contents-heading">Table of Contents</h2>

<div class="contents">

<ul class="no-bullet">
  <li><a name="toc-Preface-1" href="#Preface">1 Preface</a></li>
  <li><a name="toc-Introduction-to-GnuTLS-1" href="#Introduction-to-GnuTLS">2 Introduction to GnuTLS</a>
  <ul class="no-bullet">
    <li><a name="toc-Downloading-and-installing-1" href="#Downloading-and-installing">2.1 Downloading and installing</a></li>
    <li><a name="toc-Installing-for-a-software-distribution-1" href="#Installing-for-a-software-distribution">2.2 Installing for a software distribution</a></li>
    <li><a name="toc-Overview" href="#Document-overview">2.3 Overview</a></li>
  </ul></li>
  <li><a name="toc-Introduction-to-TLS-and-DTLS" href="#Introduction-to-TLS">3 Introduction to <acronym>TLS</acronym> and <acronym>DTLS</acronym></a>
  <ul class="no-bullet">
    <li><a name="toc-TLS-Layers" href="#TLS-layers">3.1 TLS Layers</a></li>
    <li><a name="toc-The-Transport-Layer" href="#The-transport-layer">3.2 The Transport Layer</a></li>
    <li><a name="toc-The-TLS-record-protocol-1" href="#The-TLS-record-protocol">3.3 The TLS record protocol</a>
    <ul class="no-bullet">
      <li><a name="toc-Encryption-algorithms-used-in-the-record-layer-1" href="#Encryption-algorithms-used-in-the-record-layer">3.3.1 Encryption algorithms used in the record layer</a></li>
      <li><a name="toc-Compression-algorithms-used-in-the-record-layer-1" href="#Compression-algorithms-used-in-the-record-layer">3.3.2 Compression algorithms used in the record layer</a></li>
      <li><a name="toc-Weaknesses-and-countermeasures-1" href="#Weaknesses-and-countermeasures">3.3.3 Weaknesses and countermeasures</a></li>
      <li><a name="toc-On-record-padding" href="#On-Record-Padding">3.3.4 On record padding</a></li>
    </ul></li>
    <li><a name="toc-The-TLS-alert-protocol" href="#The-TLS-Alert-Protocol">3.4 The TLS alert protocol</a></li>
    <li><a name="toc-The-TLS-handshake-protocol" href="#The-TLS-Handshake-Protocol">3.5 The TLS handshake protocol</a>
    <ul class="no-bullet">
      <li><a name="toc-TLS-ciphersuites" href="#TLS-Cipher-Suites">3.5.1 TLS ciphersuites</a></li>
      <li><a name="toc-Authentication-1" href="#Authentication">3.5.2 Authentication</a></li>
      <li><a name="toc-Client-authentication" href="#Client-Authentication">3.5.3 Client authentication</a></li>
      <li><a name="toc-Resuming-sessions" href="#Resuming-Sessions">3.5.4 Resuming sessions</a></li>
    </ul></li>
    <li><a name="toc-TLS-extensions" href="#TLS-Extensions">3.6 TLS extensions</a>
    <ul class="no-bullet">
      <li><a name="toc-Maximum-fragment-length-negotiation-1" href="#Maximum-fragment-length-negotiation">3.6.1 Maximum fragment length negotiation</a></li>
      <li><a name="toc-Server-name-indication-1" href="#Server-name-indication">3.6.2 Server name indication</a></li>
      <li><a name="toc-Session-tickets-1" href="#Session-tickets">3.6.3 Session tickets</a></li>
      <li><a name="toc-HeartBeat-1" href="#HeartBeat">3.6.4 HeartBeat</a></li>
      <li><a name="toc-Safe-renegotiation-1" href="#Safe-renegotiation">3.6.5 Safe renegotiation</a></li>
      <li><a name="toc-OCSP-status-request-1" href="#OCSP-status-request">3.6.6 OCSP status request</a></li>
      <li><a name="toc-SRTP-1" href="#SRTP">3.6.7 SRTP</a></li>
      <li><a name="toc-Application-Layer-Protocol-Negotiation-_0028ALPN_0029-1" href="#Application-Layer-Protocol-Negotiation-_0028ALPN_0029">3.6.8 Application Layer Protocol Negotiation (ALPN)</a></li>
      <li><a name="toc-Extensions-and-Supplemental-Data-1" href="#Extensions-and-Supplemental-Data">3.6.9 Extensions and Supplemental Data</a></li>
    </ul></li>
    <li><a name="toc-How-to-use-TLS-in-application-protocols-1" href="#How-to-use-TLS-in-application-protocols">3.7 How to use <acronym>TLS</acronym> in application protocols</a>
    <ul class="no-bullet">
      <li><a name="toc-Separate-ports-1" href="#Separate-ports">3.7.1 Separate ports</a></li>
      <li><a name="toc-Upward-negotiation-1" href="#Upward-negotiation">3.7.2 Upward negotiation</a></li>
    </ul></li>
    <li><a name="toc-On-SSL-2-and-older-protocols-1" href="#On-SSL-2-and-older-protocols">3.8 On SSL 2 and older protocols</a></li>
  </ul></li>
  <li><a name="toc-Authentication-methods-1" href="#Authentication-methods">4 Authentication methods</a>
  <ul class="no-bullet">
    <li><a name="toc-Certificate-authentication-1" href="#Certificate-authentication">4.1 Certificate authentication</a>
    <ul class="no-bullet">
      <li><a name="toc-X_002e509-certificates-1" href="#X_002e509-certificates">4.1.1 <acronym>X.509</acronym> certificates</a>
      <ul class="no-bullet">
        <li><a name="toc-X_002e509-certificate-structure-1" href="#X_002e509-certificate-structure">4.1.1.1 <acronym>X.509</acronym> certificate structure</a></li>
        <li><a name="toc-Importing-an-X_002e509-certificate-1" href="#Importing-an-X_002e509-certificate">4.1.1.2 Importing an X.509 certificate</a></li>
        <li><a name="toc-X_002e509-certificate-names-1" href="#X_002e509-certificate-names">4.1.1.3 X.509 certificate names</a></li>
        <li><a name="toc-X_002e509-distinguished-names-1" href="#X_002e509-distinguished-names">4.1.1.4 X.509 distinguished names</a></li>
        <li><a name="toc-X_002e509-extensions-1" href="#X_002e509-extensions">4.1.1.5 X.509 extensions</a></li>
        <li><a name="toc-Accessing-public-and-private-keys" href="#X_002e509-public-and-private-keys">4.1.1.6 Accessing public and private keys</a></li>
        <li><a name="toc-Verifying-X_002e509-certificate-paths-1" href="#Verifying-X_002e509-certificate-paths">4.1.1.7 Verifying <acronym>X.509</acronym> certificate paths</a></li>
        <li><a name="toc-Verifying-a-certificate-in-the-context-of-TLS-session-1" href="#Verifying-a-certificate-in-the-context-of-TLS-session">4.1.1.8 Verifying a certificate in the context of TLS session</a></li>
        <li><a name="toc-Verifying-a-certificate-using-PKCS-_002311" href="#Verification-using-PKCS11">4.1.1.9 Verifying a certificate using PKCS #11</a></li>
      </ul></li>
      <li><a name="toc-OpenPGP-certificates-1" href="#OpenPGP-certificates">4.1.2 <acronym>OpenPGP</acronym> certificates</a>
      <ul class="no-bullet">
        <li><a name="toc-OpenPGP-certificate-structure" href="#OpenPGP-certificate-structure">4.1.2.1 <acronym>OpenPGP</acronym> certificate structure</a></li>
        <li><a name="toc-Verifying-an-OpenPGP-certificate" href="#Verifying-an-OpenPGP-certificate">4.1.2.2 Verifying an <acronym>OpenPGP</acronym> certificate</a></li>
        <li><a name="toc-Verifying-a-certificate-in-the-context-of-a-TLS-session" href="#Verifying-a-certificate-in-the-context-of-a-TLS-session">4.1.2.3 Verifying a certificate in the context of a TLS session</a></li>
      </ul></li>
      <li><a name="toc-Advanced-certificate-verification-1" href="#Advanced-certificate-verification">4.1.3 Advanced certificate verification</a>
      <ul class="no-bullet">
        <li><a name="toc-Verifying-a-certificate-using-trust-on-first-use-authentication-1" href="#Verifying-a-certificate-using-trust-on-first-use-authentication">4.1.3.1 Verifying a certificate using trust on first use authentication</a></li>
        <li><a name="toc-Verifying-a-certificate-using-DANE-_0028DNSSEC_0029" href="#Verifying-a-certificate-using-DANE">4.1.3.2 Verifying a certificate using DANE (DNSSEC)</a></li>
      </ul></li>
      <li><a name="toc-Digital-signatures-1" href="#Digital-signatures">4.1.4 Digital signatures</a>
      <ul class="no-bullet">
        <li><a name="toc-Trading-security-for-interoperability" href="#Trading-security-for-interoperability">4.1.4.1 Trading security for interoperability</a></li>
      </ul></li>
    </ul></li>
    <li><a name="toc-More-on-certificate-authentication-1" href="#More-on-certificate-authentication">4.2 More on certificate authentication</a>
    <ul class="no-bullet">
      <li><a name="toc-PKCS-_002310-certificate-requests" href="#PKCS-10-certificate-requests">4.2.1 <acronym>PKCS</acronym> #10 certificate requests</a></li>
      <li><a name="toc-PKIX-certificate-revocation-lists-1" href="#PKIX-certificate-revocation-lists">4.2.2 PKIX certificate revocation lists</a></li>
      <li><a name="toc-OCSP-certificate-status-checking-1" href="#OCSP-certificate-status-checking">4.2.3 <acronym>OCSP</acronym> certificate status checking</a></li>
      <li><a name="toc-Managing-encrypted-keys-1" href="#Managing-encrypted-keys">4.2.4 Managing encrypted keys</a></li>
      <li><a name="toc-Invoking-certtool" href="#certtool-Invocation">4.2.5 Invoking certtool</a></li>
      <li><a name="toc-Invoking-ocsptool" href="#ocsptool-Invocation">4.2.6 Invoking ocsptool</a></li>
      <li><a name="toc-Invoking-danetool" href="#danetool-Invocation">4.2.7 Invoking danetool</a></li>
    </ul></li>
    <li><a name="toc-Shared_002dkey-and-anonymous-authentication-1" href="#Shared_002dkey-and-anonymous-authentication">4.3 Shared-key and anonymous authentication</a>
    <ul class="no-bullet">
      <li><a name="toc-SRP-authentication-1" href="#SRP-authentication">4.3.1 SRP authentication</a>
      <ul class="no-bullet">
        <li><a name="toc-Authentication-using-SRP-1" href="#Authentication-using-SRP">4.3.1.1 Authentication using <acronym>SRP</acronym></a></li>
        <li><a name="toc-Invoking-srptool" href="#srptool-Invocation">4.3.1.2 Invoking srptool</a></li>
      </ul></li>
      <li><a name="toc-PSK-authentication-1" href="#PSK-authentication">4.3.2 PSK authentication</a>
      <ul class="no-bullet">
        <li><a name="toc-Authentication-using-PSK-1" href="#Authentication-using-PSK">4.3.2.1 Authentication using <acronym>PSK</acronym></a></li>
        <li><a name="toc-Invoking-psktool" href="#psktool-Invocation">4.3.2.2 Invoking psktool</a></li>
      </ul></li>
      <li><a name="toc-Anonymous-authentication-1" href="#Anonymous-authentication">4.3.3 Anonymous authentication</a></li>
    </ul></li>
    <li><a name="toc-Selecting-an-appropriate-authentication-method-1" href="#Selecting-an-appropriate-authentication-method">4.4 Selecting an appropriate authentication method</a>
    <ul class="no-bullet">
      <li><a name="toc-Two-peers-with-an-out_002dof_002dband-channel" href="#Two-peers-with-an-out_002dof_002dband-channel">4.4.1 Two peers with an out-of-band channel</a></li>
      <li><a name="toc-Two-peers-without-an-out_002dof_002dband-channel" href="#Two-peers-without-an-out_002dof_002dband-channel">4.4.2 Two peers without an out-of-band channel</a></li>
      <li><a name="toc-Two-peers-and-a-trusted-third-party" href="#Two-peers-and-a-trusted-third-party">4.4.3 Two peers and a trusted third party</a></li>
    </ul></li>
  </ul></li>
  <li><a name="toc-Abstract-keys-types-and-Hardware-security-modules" href="#Hardware-security-modules-and-abstract-key-types">5 Abstract keys types and Hardware security modules</a>
  <ul class="no-bullet">
    <li><a name="toc-Abstract-key-types-1" href="#Abstract-key-types">5.1 Abstract key types</a>
    <ul class="no-bullet">
      <li><a name="toc-Public-keys" href="#Abstract-public-keys">5.1.1 Public keys</a></li>
      <li><a name="toc-Private-keys" href="#Abstract-private-keys">5.1.2 Private keys</a></li>
      <li><a name="toc-Operations-1" href="#Operations">5.1.3 Operations</a></li>
    </ul></li>
    <li><a name="toc-System-and-application_002dspecific-keys" href="#Application_002dspecific-keys">5.2 System and application-specific keys</a>
    <ul class="no-bullet">
      <li><a name="toc-System_002dspecific-keys" href="#System_002dspecific-keys">5.2.1 System-specific keys</a></li>
      <li><a name="toc-Application_002dspecific-keys-1" href="#Application_002dspecific-keys-1">5.2.2 Application-specific keys</a></li>
    </ul></li>
    <li><a name="toc-Smart-cards-and-HSMs-1" href="#Smart-cards-and-HSMs">5.3 Smart cards and HSMs</a>
    <ul class="no-bullet">
      <li><a name="toc-Initialization-1" href="#PKCS11-Initialization">5.3.1 Initialization</a></li>
      <li><a name="toc-Accessing-objects-that-require-a-PIN-1" href="#Accessing-objects-that-require-a-PIN">5.3.2 Accessing objects that require a PIN</a></li>
      <li><a name="toc-Reading-objects-1" href="#Reading-objects">5.3.3 Reading objects</a></li>
      <li><a name="toc-Writing-objects-1" href="#Writing-objects">5.3.4 Writing objects</a></li>
      <li><a name="toc-Using-a-PKCS-_002311-token-with-TLS" href="#Using-a-PKCS11-token-with-TLS">5.3.5 Using a <acronym>PKCS</acronym> #11 token with TLS</a></li>
      <li><a name="toc-Invoking-p11tool" href="#p11tool-Invocation">5.3.6 Invoking p11tool</a></li>
      <li><a name="toc-p11tool-help_002fusage-_0028_002d_002dhelp_0029" href="#p11tool-help_002fusage-_0028_002d_002dhelp_0029">5.3.7 p11tool help/usage (<samp>--help</samp>)</a></li>
      <li><a name="toc-token_002drelated_002doptions-options" href="#token_002drelated_002doptions-options">5.3.8 token-related-options options</a></li>
      <li><a name="toc-object_002dlist_002drelated_002doptions-options" href="#object_002dlist_002drelated_002doptions-options">5.3.9 object-list-related-options options</a></li>
      <li><a name="toc-keygen_002drelated_002doptions-options" href="#keygen_002drelated_002doptions-options">5.3.10 keygen-related-options options</a></li>
      <li><a name="toc-write_002dobject_002drelated_002doptions-options" href="#write_002dobject_002drelated_002doptions-options">5.3.11 write-object-related-options options</a></li>
      <li><a name="toc-other_002doptions-options" href="#other_002doptions-options">5.3.12 other-options options</a></li>
      <li><a name="toc-p11tool-exit-status-1" href="#p11tool-exit-status-1">5.3.13 p11tool exit status</a></li>
      <li><a name="toc-p11tool-See-Also-1" href="#p11tool-See-Also-1">5.3.14 p11tool See Also</a></li>
      <li><a name="toc-p11tool-Examples-1" href="#p11tool-Examples-1">5.3.15 p11tool Examples</a></li>
    </ul></li>
    <li><a name="toc-Trusted-Platform-Module-_0028TPM_0029" href="#Trusted-Platform-Module">5.4 Trusted Platform Module (TPM)</a>
    <ul class="no-bullet">
      <li><a name="toc-Keys-in-TPM-1" href="#Keys-in-TPM">5.4.1 Keys in TPM</a></li>
      <li><a name="toc-Key-generation-1" href="#Key-generation">5.4.2 Key generation</a></li>
      <li><a name="toc-Using-keys-1" href="#Using-keys">5.4.3 Using keys</a></li>
      <li><a name="toc-Invoking-tpmtool" href="#tpmtool-Invocation">5.4.4 Invoking tpmtool</a></li>
      <li><a name="toc-tpmtool-help_002fusage-_0028_002d_002dhelp_0029" href="#tpmtool-help_002fusage-_0028_002d_002dhelp_0029">5.4.5 tpmtool help/usage (<samp>--help</samp>)</a></li>
      <li><a name="toc-debug-option-_0028_002dd_0029" href="#debug-option-_0028_002dd_0029">5.4.6 debug option (-d)</a></li>
      <li><a name="toc-generate_002drsa-option" href="#generate_002drsa-option">5.4.7 generate-rsa option</a></li>
      <li><a name="toc-user-option" href="#user-option">5.4.8 user option</a></li>
      <li><a name="toc-system-option" href="#system-option">5.4.9 system option</a></li>
      <li><a name="toc-test_002dsign-option" href="#test_002dsign-option">5.4.10 test-sign option</a></li>
      <li><a name="toc-sec_002dparam-option" href="#sec_002dparam-option">5.4.11 sec-param option</a></li>
      <li><a name="toc-inder-option" href="#inder-option">5.4.12 inder option</a></li>
      <li><a name="toc-outder-option" href="#outder-option">5.4.13 outder option</a></li>
      <li><a name="toc-tpmtool-exit-status-1" href="#tpmtool-exit-status-1">5.4.14 tpmtool exit status</a></li>
      <li><a name="toc-tpmtool-See-Also-1" href="#tpmtool-See-Also-1">5.4.15 tpmtool See Also</a></li>
      <li><a name="toc-tpmtool-Examples-1" href="#tpmtool-Examples-1">5.4.16 tpmtool Examples</a></li>
    </ul></li>
  </ul></li>
  <li><a name="toc-How-to-use-GnuTLS-in-applications-1" href="#How-to-use-GnuTLS-in-applications">6 How to use <acronym>GnuTLS</acronym> in applications</a>
  <ul class="no-bullet">
    <li><a name="toc-Introduction" href="#Introduction-to-the-library">6.1 Introduction</a>
    <ul class="no-bullet">
      <li><a name="toc-General-idea-1" href="#General-idea">6.1.1 General idea</a></li>
      <li><a name="toc-Error-handling-1" href="#Error-handling">6.1.2 Error handling</a></li>
      <li><a name="toc-Common-types-1" href="#Common-types">6.1.3 Common types</a></li>
      <li><a name="toc-Debugging-and-auditing-1" href="#Debugging-and-auditing">6.1.4 Debugging and auditing</a></li>
      <li><a name="toc-Thread-safety-1" href="#Thread-safety">6.1.5 Thread safety</a></li>
      <li><a name="toc-Running-in-a-sandbox-1" href="#Running-in-a-sandbox">6.1.6 Running in a sandbox</a></li>
      <li><a name="toc-Sessions-and-fork-1" href="#Sessions-and-fork">6.1.7 Sessions and fork</a></li>
      <li><a name="toc-Callback-functions-1" href="#Callback-functions">6.1.8 Callback functions</a></li>
    </ul></li>
    <li><a name="toc-Preparation-1" href="#Preparation">6.2 Preparation</a>
    <ul class="no-bullet">
      <li><a name="toc-Headers-1" href="#Headers">6.2.1 Headers</a></li>
      <li><a name="toc-Initialization-2" href="#Initialization">6.2.2 Initialization</a></li>
      <li><a name="toc-Version-check-1" href="#Version-check">6.2.3 Version check</a></li>
      <li><a name="toc-Building-the-source-1" href="#Building-the-source">6.2.4 Building the source</a></li>
    </ul></li>
    <li><a name="toc-Session-initialization-1" href="#Session-initialization">6.3 Session initialization</a></li>
    <li><a name="toc-Associating-the-credentials-1" href="#Associating-the-credentials">6.4 Associating the credentials</a>
    <ul class="no-bullet">
      <li><a name="toc-Certificates" href="#Certificate-credentials">6.4.1 Certificates</a></li>
      <li><a name="toc-SRP" href="#SRP-credentials">6.4.2 SRP</a></li>
      <li><a name="toc-PSK" href="#PSK-credentials">6.4.3 PSK</a></li>
      <li><a name="toc-Anonymous" href="#Anonymous-credentials">6.4.4 Anonymous</a></li>
    </ul></li>
    <li><a name="toc-Setting-up-the-transport-layer-1" href="#Setting-up-the-transport-layer">6.5 Setting up the transport layer</a>
    <ul class="no-bullet">
      <li><a name="toc-Asynchronous-operation-1" href="#Asynchronous-operation">6.5.1 Asynchronous operation</a>
      <ul class="no-bullet">
        <li><a name="toc-TLS-protocol" href="#TLS-protocol">6.5.1.1 TLS protocol</a></li>
        <li><a name="toc-Datagram-TLS-protocol" href="#Datagram-TLS-protocol">6.5.1.2 Datagram TLS protocol</a></li>
      </ul></li>
      <li><a name="toc-DTLS-sessions-1" href="#DTLS-sessions">6.5.2 DTLS sessions</a></li>
    </ul></li>
    <li><a name="toc-TLS-handshake-1" href="#TLS-handshake">6.6 TLS handshake</a></li>
    <li><a name="toc-Data-transfer-and-termination-1" href="#Data-transfer-and-termination">6.7 Data transfer and termination</a></li>
    <li><a name="toc-Buffered-data-transfer-1" href="#Buffered-data-transfer">6.8 Buffered data transfer</a></li>
    <li><a name="toc-Handling-alerts-1" href="#Handling-alerts">6.9 Handling alerts</a></li>
    <li><a name="toc-Priority-strings" href="#Priority-Strings">6.10 Priority strings</a></li>
    <li><a name="toc-Selecting-cryptographic-key-sizes-1" href="#Selecting-cryptographic-key-sizes">6.11 Selecting cryptographic key sizes</a></li>
    <li><a name="toc-Advanced-topics-1" href="#Advanced-topics">6.12 Advanced topics</a>
    <ul class="no-bullet">
      <li><a name="toc-Session-resumption-1" href="#Session-resumption">6.12.1 Session resumption</a></li>
      <li><a name="toc-Certificate-verification-1" href="#Certificate-verification">6.12.2 Certificate verification</a>
      <ul class="no-bullet">
        <li><a name="toc-Trust-on-first-use" href="#Trust-on-first-use">6.12.2.1 Trust on first use</a></li>
        <li><a name="toc-DANE-verification" href="#DANE-verification">6.12.2.2 DANE verification</a></li>
      </ul></li>
      <li><a name="toc-Re_002dauthentication-1" href="#Re_002dauthentication">6.12.3 Re-authentication</a>
      <ul class="no-bullet">
        <li><a name="toc-Client-side" href="#Client-side">6.12.3.1 Client side</a></li>
        <li><a name="toc-Server-side" href="#Server-side">6.12.3.2 Server side</a></li>
      </ul></li>
      <li><a name="toc-Parameter-generation-1" href="#Parameter-generation">6.12.4 Parameter generation</a></li>
      <li><a name="toc-Deriving-keys-for-other-applications_002fprotocols-1" href="#Deriving-keys-for-other-applications_002fprotocols">6.12.5 Deriving keys for other applications/protocols</a></li>
      <li><a name="toc-Channel-bindings" href="#Channel-Bindings">6.12.6 Channel bindings</a></li>
      <li><a name="toc-Interoperability-1" href="#Interoperability">6.12.7 Interoperability</a></li>
      <li><a name="toc-Compatibility-with-the-OpenSSL-library-1" href="#Compatibility-with-the-OpenSSL-library">6.12.8 Compatibility with the OpenSSL library</a></li>
    </ul></li>
  </ul></li>
  <li><a name="toc-GnuTLS-application-examples-1" href="#GnuTLS-application-examples">7 GnuTLS application examples</a>
  <ul class="no-bullet">
    <li><a name="toc-Client-examples-1" href="#Client-examples">7.1 Client examples</a>
    <ul class="no-bullet">
      <li><a name="toc-Simple-client-example-with-X_002e509-certificate-support-1" href="#Simple-client-example-with-X_002e509-certificate-support">7.1.1 Simple client example with <acronym>X.509</acronym> certificate support</a></li>
      <li><a name="toc-Simple-client-example-with-SSH_002dstyle-certificate-verification-1" href="#Simple-client-example-with-SSH_002dstyle-certificate-verification">7.1.2 Simple client example with SSH-style certificate verification</a></li>
      <li><a name="toc-Simple-client-example-with-anonymous-authentication-1" href="#Simple-client-example-with-anonymous-authentication">7.1.3 Simple client example with anonymous authentication</a></li>
      <li><a name="toc-Simple-datagram-TLS-client-example" href="#Simple-Datagram-TLS-client-example">7.1.4 Simple datagram <acronym>TLS</acronym> client example</a></li>
      <li><a name="toc-Obtaining-session-information-1" href="#Obtaining-session-information">7.1.5 Obtaining session information</a></li>
      <li><a name="toc-Using-a-callback-to-select-the-certificate-to-use-1" href="#Using-a-callback-to-select-the-certificate-to-use">7.1.6 Using a callback to select the certificate to use</a></li>
      <li><a name="toc-Verifying-a-certificate-1" href="#Verifying-a-certificate">7.1.7 Verifying a certificate</a></li>
      <li><a name="toc-Using-a-smart-card-with-TLS" href="#Client-using-a-smart-card-with-TLS">7.1.8 Using a smart card with TLS</a></li>
      <li><a name="toc-Client-with-resume-capability-example" href="#Client-with-Resume-capability-example">7.1.9 Client with resume capability example</a></li>
      <li><a name="toc-Simple-client-example-with-SRP-authentication-1" href="#Simple-client-example-with-SRP-authentication">7.1.10 Simple client example with <acronym>SRP</acronym> authentication</a></li>
      <li><a name="toc-Simple-client-example-using-the-C_002b_002b-API" href="#Simple-client-example-in-C_002b_002b">7.1.11 Simple client example using the C++ API</a></li>
      <li><a name="toc-Helper-functions-for-TCP-connections-1" href="#Helper-functions-for-TCP-connections">7.1.12 Helper functions for TCP connections</a></li>
      <li><a name="toc-Helper-functions-for-UDP-connections-1" href="#Helper-functions-for-UDP-connections">7.1.13 Helper functions for UDP connections</a></li>
    </ul></li>
    <li><a name="toc-Server-examples-1" href="#Server-examples">7.2 Server examples</a>
    <ul class="no-bullet">
      <li><a name="toc-Echo-server-with-X_002e509-authentication-1" href="#Echo-server-with-X_002e509-authentication">7.2.1 Echo server with <acronym>X.509</acronym> authentication</a></li>
      <li><a name="toc-Echo-server-with-OpenPGP-authentication-1" href="#Echo-server-with-OpenPGP-authentication">7.2.2 Echo server with <acronym>OpenPGP</acronym> authentication</a></li>
      <li><a name="toc-Echo-server-with-SRP-authentication-1" href="#Echo-server-with-SRP-authentication">7.2.3 Echo server with <acronym>SRP</acronym> authentication</a></li>
      <li><a name="toc-Echo-server-with-anonymous-authentication-1" href="#Echo-server-with-anonymous-authentication">7.2.4 Echo server with anonymous authentication</a></li>
      <li><a name="toc-DTLS-echo-server-with-X_002e509-authentication-1" href="#DTLS-echo-server-with-X_002e509-authentication">7.2.5 DTLS echo server with <acronym>X.509</acronym> authentication</a></li>
    </ul></li>
    <li><a name="toc-OCSP-example-1" href="#OCSP-example">7.3 OCSP example</a></li>
    <li><a name="toc-Miscellaneous-examples-1" href="#Miscellaneous-examples">7.4 Miscellaneous examples</a>
    <ul class="no-bullet">
      <li><a name="toc-Checking-for-an-alert-1" href="#Checking-for-an-alert">7.4.1 Checking for an alert</a></li>
      <li><a name="toc-X_002e509-certificate-parsing-example-1" href="#X_002e509-certificate-parsing-example">7.4.2 <acronym>X.509</acronym> certificate parsing example</a></li>
      <li><a name="toc-Listing-the-ciphersuites-in-a-priority-string-1" href="#Listing-the-ciphersuites-in-a-priority-string">7.4.3 Listing the ciphersuites in a priority string</a></li>
      <li><a name="toc-PKCS-_002312-structure-generation-example" href="#PKCS12-structure-generation-example">7.4.4 PKCS #12 structure generation example</a></li>
    </ul></li>
  </ul></li>
  <li><a name="toc-Using-GnuTLS-as-a-cryptographic-library-1" href="#Using-GnuTLS-as-a-cryptographic-library">8 Using GnuTLS as a cryptographic library</a>
  <ul class="no-bullet">
    <li><a name="toc-Symmetric-algorithms-1" href="#Symmetric-algorithms">8.1 Symmetric algorithms</a></li>
    <li><a name="toc-Public-key-algorithms-1" href="#Public-key-algorithms">8.2 Public key algorithms</a>
    <ul class="no-bullet">
      <li><a name="toc-PKCS-_00237-signing" href="#PKCS-_00237-signing">8.2.1 PKCS #7 signing</a></li>
    </ul></li>
    <li><a name="toc-Hash-and-MAC-functions-1" href="#Hash-and-MAC-functions">8.3 Hash and MAC functions</a></li>
    <li><a name="toc-Random-number-generation-1" href="#Random-number-generation">8.4 Random number generation</a></li>
    <li><a name="toc-Overriding-algorithms-1" href="#Overriding-algorithms">8.5 Overriding algorithms</a></li>
  </ul></li>
  <li><a name="toc-Other-included-programs-1" href="#Other-included-programs">9 Other included programs</a>
  <ul class="no-bullet">
    <li><a name="toc-Invoking-gnutls_002dcli" href="#gnutls_002dcli-Invocation">9.1 Invoking gnutls-cli</a></li>
    <li><a name="toc-Invoking-gnutls_002dserv" href="#gnutls_002dserv-Invocation">9.2 Invoking gnutls-serv</a></li>
    <li><a name="toc-Invoking-gnutls_002dcli_002ddebug" href="#gnutls_002dcli_002ddebug-Invocation">9.3 Invoking gnutls-cli-debug</a></li>
  </ul></li>
  <li><a name="toc-Internal-Architecture-of-GnuTLS" href="#Internal-architecture-of-GnuTLS">10 Internal Architecture of GnuTLS</a>
  <ul class="no-bullet">
    <li><a name="toc-The-TLS-Protocol-1" href="#The-TLS-Protocol">10.1 The TLS Protocol</a></li>
    <li><a name="toc-TLS-Handshake-Protocol-1" href="#TLS-Handshake-Protocol">10.2 TLS Handshake Protocol</a></li>
    <li><a name="toc-TLS-Authentication-Methods-1" href="#TLS-Authentication-Methods">10.3 TLS Authentication Methods</a></li>
    <li><a name="toc-TLS-Extension-Handling-1" href="#TLS-Extension-Handling">10.4 TLS Extension Handling</a></li>
    <li><a name="toc-Cryptographic-Backend-1" href="#Cryptographic-Backend">10.5 Cryptographic Backend</a></li>
  </ul></li>
  <li><a name="toc-Upgrading-from-previous-versions-1" href="#Upgrading-from-previous-versions">Appendix A Upgrading from previous versions</a></li>
  <li><a name="toc-Support-1" href="#Support">Appendix B Support</a>
  <ul class="no-bullet">
    <li><a name="toc-Getting-Help" href="#Getting-help">B.1 Getting Help</a></li>
    <li><a name="toc-Commercial-Support-1" href="#Commercial-Support">B.2 Commercial Support</a></li>
    <li><a name="toc-Bug-Reports-1" href="#Bug-Reports">B.3 Bug Reports</a></li>
    <li><a name="toc-Contributing-1" href="#Contributing">B.4 Contributing</a></li>
    <li><a name="toc-Certification-1" href="#Certification">B.5 Certification</a></li>
  </ul></li>
  <li><a name="toc-Error-Codes-and-Descriptions" href="#Error-codes">Appendix C Error Codes and Descriptions</a></li>
  <li><a name="toc-Supported-Ciphersuites" href="#Supported-ciphersuites">Appendix D Supported Ciphersuites</a></li>
  <li><a name="toc-API-reference-1" href="#API-reference">Appendix E API reference</a>
  <ul class="no-bullet">
    <li><a name="toc-Core-TLS-API-1" href="#Core-TLS-API">E.1 Core TLS API</a></li>
    <li><a name="toc-Datagram-TLS-API-1" href="#Datagram-TLS-API">E.2 Datagram TLS API</a></li>
    <li><a name="toc-X_002e509-certificate-API" href="#X509-certificate-API">E.3 <acronym>X.509</acronym> certificate API</a></li>
    <li><a name="toc-PKCS-7-API-1" href="#PKCS-7-API">E.4 <acronym>PKCS</acronym> 7 API</a></li>
    <li><a name="toc-OCSP-API-1" href="#OCSP-API">E.5 <acronym>OCSP</acronym> API</a></li>
    <li><a name="toc-OpenPGP-API-1" href="#OpenPGP-API">E.6 <acronym>OpenPGP</acronym> API</a></li>
    <li><a name="toc-PKCS-12-API-1" href="#PKCS-12-API">E.7 PKCS 12 API</a></li>
    <li><a name="toc-Hardware-token-via-PKCS-11-API" href="#PKCS-11-API">E.8 Hardware token via PKCS 11 API</a></li>
    <li><a name="toc-TPM-API-1" href="#TPM-API">E.9 TPM API</a></li>
    <li><a name="toc-Abstract-key-API-1" href="#Abstract-key-API">E.10 Abstract key API</a></li>
    <li><a name="toc-DANE-API-1" href="#DANE-API">E.11 DANE API</a></li>
    <li><a name="toc-Cryptographic-API-1" href="#Cryptographic-API">E.12 Cryptographic API</a></li>
    <li><a name="toc-Compatibility-API-1" href="#Compatibility-API">E.13 Compatibility API</a></li>
  </ul></li>
  <li><a name="toc-Copying-Information-1" href="#Copying-Information">Appendix F Copying Information</a></li>
  <li><a name="toc-Bibliography-1" href="#Bibliography">Bibliography</a></li>
  <li><a name="toc-Function-and-Data-Index-1" href="#Function-and-Data-Index">Function and Data Index</a></li>
  <li><a name="toc-Concept-Index-1" href="#Concept-Index">Concept Index</a></li>
</ul>
</div>


<a name="Top"></a>
<div class="header">
<p>
Next: <a href="#Preface" accesskey="n" rel="next">Preface</a>, Up: <a href="dir.html#Top" accesskey="u" rel="up">(dir)</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GnuTLS"></a>
<h1 class="top">GnuTLS</h1>

<p>This manual is last updated 4 March 2015 for version
3.4.8 of GnuTLS.
</p>
<p>Copyright &copy; 2001-2015 Free Software Foundation, Inc.\\
Copyright &copy; 2001-2015 Nikos Mavrogiannopoulos
</p>
<blockquote>
<p>Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.  A
copy of the license is included in the section entitled &ldquo;GNU Free
Documentation License&rdquo;.
</p></blockquote>


<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Preface" accesskey="1">Preface</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Introduction-to-GnuTLS" accesskey="2">Introduction to GnuTLS</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Introduction-to-TLS" accesskey="3">Introduction to TLS</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Authentication-methods" accesskey="4">Authentication methods</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Hardware-security-modules-and-abstract-key-types" accesskey="5">Hardware security modules and abstract key types</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#How-to-use-GnuTLS-in-applications" accesskey="6">How to use GnuTLS in applications</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#GnuTLS-application-examples" accesskey="7">GnuTLS application examples</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Using-GnuTLS-as-a-cryptographic-library" accesskey="8">Using GnuTLS as a cryptographic library</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Other-included-programs" accesskey="9">Other included programs</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Internal-architecture-of-GnuTLS">Internal architecture of GnuTLS</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Upgrading-from-previous-versions">Upgrading from previous versions</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Support">Support</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Error-codes">Error codes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Supported-ciphersuites">Supported ciphersuites</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#API-reference">API reference</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Copying-Information">Copying Information</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Bibliography">Bibliography</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Function-and-Data-Index">Function and Data Index</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Concept-Index">Concept Index</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Preface"></a>
<div class="header">
<p>
Next: <a href="#Introduction-to-GnuTLS" accesskey="n" rel="next">Introduction to GnuTLS</a>, Previous: <a href="#Top" accesskey="p" rel="prev">Top</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Preface-1"></a>
<h2 class="chapter">1 Preface</h2>

<p>This document demonstrates and explains the <acronym>GnuTLS</acronym>
library API.  A brief introduction to the protocols and the technology
involved is also included so that an application programmer can
better understand the <acronym>GnuTLS</acronym> purpose and actual offerings.
Even if <acronym>GnuTLS</acronym> is a typical library software, it operates
over several security and cryptographic protocols which require the
programmer to make careful and correct usage of them. Otherwise it
is likely to only obtain a false sense of security.
The term of security is very broad even if restricted to computer
software, and cannot be confined to a single cryptographic
library.  For that reason, do not consider any program secure just
because it uses <acronym>GnuTLS</acronym>; there are several ways to compromise
a program or a communication line and <acronym>GnuTLS</acronym> only helps with
some of them.
</p>
<p>Although this document tries to be self contained, basic network
programming and public key infrastructure (PKI) knowledge is assumed 
in most of it. A good introduction to networking can be found 
in [<em>STEVENS</em>], to public key infrastructure in [<em>GUTPKI</em>]
and to security engineering in [<em>ANDERSON</em>].
</p>
<p>Updated versions of the <acronym>GnuTLS</acronym> software and this document
will be available from <a href="http://www.gnutls.org/">http://www.gnutls.org/</a>.
</p>
<hr>
<a name="Introduction-to-GnuTLS"></a>
<div class="header">
<p>
Next: <a href="#Introduction-to-TLS" accesskey="n" rel="next">Introduction to TLS</a>, Previous: <a href="#Preface" accesskey="p" rel="prev">Preface</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Introduction-to-GnuTLS-1"></a>
<h2 class="chapter">2 Introduction to GnuTLS</h2>

<p>In brief <acronym>GnuTLS</acronym> can be described as a library which offers an API
to access secure communication protocols. These protocols provide
privacy over insecure lines, and were designed to prevent
eavesdropping, tampering, or message forgery.
</p>
<p>Technically <acronym>GnuTLS</acronym> is a portable ANSI C based library which
implements the protocols ranging from SSL 3.0 to TLS 1.2 (see <a href="#Introduction-to-TLS">Introduction to TLS</a>, 
for a detailed description of the protocols), accompanied
with the required framework for authentication and public key
infrastructure.  Important features of the <acronym>GnuTLS</acronym> library
include:
</p>
<ul>
<li> Support for TLS 1.2, TLS 1.1, TLS 1.0 and SSL 3.0 protocols.

</li><li> Support for Datagram TLS 1.0 and 1.2.

</li><li> Support for handling and verification of <acronym>X.509</acronym> and <acronym>OpenPGP</acronym> certificates.

</li><li> Support for password authentication using <acronym>TLS-SRP</acronym>.

</li><li> Support for keyed authentication using <acronym>TLS-PSK</acronym>.

</li><li> Support for TPM, <acronym>PKCS</acronym> #11 tokens and smart-cards.

</li></ul>

<p>The <acronym>GnuTLS</acronym> library consists of three independent parts, namely the &ldquo;TLS
protocol part&rdquo;, the &ldquo;Certificate part&rdquo;, and the &ldquo;Cryptographic
back-end&rdquo; part.  The &ldquo;TLS protocol part&rdquo; is the actual protocol
implementation, and is entirely implemented within the
<acronym>GnuTLS</acronym> library.  The &ldquo;Certificate part&rdquo; consists of the
certificate parsing, and verification functions and it uses
functionality from the
libtasn1 library.
The &ldquo;Cryptographic back-end&rdquo; is provided by the nettle
and gmplib libraries.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Downloading-and-installing" accesskey="1">Downloading and installing</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Installing-for-a-software-distribution" accesskey="2">Installing for a software distribution</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Document-overview" accesskey="3">Document overview</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Downloading-and-installing"></a>
<div class="header">
<p>
Next: <a href="#Installing-for-a-software-distribution" accesskey="n" rel="next">Installing for a software distribution</a>, Up: <a href="#Introduction-to-GnuTLS" accesskey="u" rel="up">Introduction to GnuTLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Downloading-and-installing-1"></a>
<h3 class="section">2.1 Downloading and installing</h3>
<a name="index-installation"></a>
<a name="index-download"></a>

<p>GnuTLS is available for download at:
<a href="http://www.gnutls.org/download.html">http://www.gnutls.org/download.html</a>
</p>
<p>GnuTLS uses a development cycle where even minor version numbers
indicate a stable release and a odd minor version number indicate a
development release.  For example, GnuTLS 1.6.3 denote a stable
release since 6 is even, and GnuTLS 1.7.11 denote a development
release since 7 is odd.
</p>
<p>GnuTLS depends on <code>nettle</code> and <code>gmplib</code>, and you will need to install it
before installing GnuTLS.  The <code>nettle</code> library is available from
<a href="http://www.lysator.liu.se/~nisse/nettle/">http://www.lysator.liu.se/~nisse/nettle/</a>, while <code>gmplib</code> is available
from <a href="http://www.gmplib.org/">http://www.gmplib.org/</a>.
Don&rsquo;t forget to verify the cryptographic signature after downloading
source code packages.
</p>
<p>The package is then extracted, configured and built like many other
packages that use Autoconf.  For detailed information on configuring
and building it, refer to the <samp>INSTALL</samp> file that is part of the
distribution archive.  Typically you invoke <code>./configure</code> and
then <code>make check install</code>.  There are a number of compile-time
parameters, as discussed below.
</p>
<p>Several parts of GnuTLS require ASN.1 functionality, which is provided by 
a library called libtasn1.  A copy of libtasn1 is included in GnuTLS.  If you
want to install it separately (e.g., to make it possibly to use
libtasn1 in other programs), you can get it from
<a href="http://www.gnu.org/software/libtasn1/">http://www.gnu.org/software/libtasn1/</a>.
</p>
<p>The compression library, <code>libz</code>, the PKCS #11 helper library <code>p11-kit</code>,
the TPM library <code>trousers</code>, as well as the IDN library <code>libidn</code><a name="DOCF1" href="#FOOT1"><sup>1</sup></a> are 
optional dependencies. Check the README file in the distribution on how
to obtain these libraries.
</p>
<p>A few <code>configure</code> options may be relevant, summarized below.
They disable or enable particular features,
to create a smaller library with only the required features.
Note however, that although a smaller library is generated, the
included programs are not guaranteed to compile if some of these
options are given.
</p>
<pre class="verbatim">--disable-srp-authentication
--disable-psk-authentication
--disable-anon-authentication
--disable-openpgp-authentication
--disable-dhe
--disable-ecdhe
--disable-openssl-compatibility
--disable-dtls-srtp-support
--disable-alpn-support
--disable-heartbeat-support
--disable-libdane
--without-p11-kit
--without-tpm
--without-zlib

</pre>
<p>For the complete list, refer to the output from <code>configure --help</code>.
</p>
<hr>
<a name="Installing-for-a-software-distribution"></a>
<div class="header">
<p>
Next: <a href="#Document-overview" accesskey="n" rel="next">Document overview</a>, Previous: <a href="#Downloading-and-installing" accesskey="p" rel="prev">Downloading and installing</a>, Up: <a href="#Introduction-to-GnuTLS" accesskey="u" rel="up">Introduction to GnuTLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Installing-for-a-software-distribution-1"></a>
<h3 class="section">2.2 Installing for a software distribution</h3>
<a name="index-installation-1"></a>

<p>When installing for a software distribution, it is often desirable to preconfigure
GnuTLS with the system-wide paths and files. There two important configuration
options, one sets the trust store in system, which are the CA certificates
to be used by programs by default (if they don&rsquo;t override it), and the other sets
to DNSSEC root key file used by unbound for DNSSEC verification.
</p>
<p>For the latter the following configuration option is available, and if not specified
GnuTLS will try to auto-detect the location of that file.
</p><pre class="verbatim">--with-unbound-root-key-file

</pre>
<p>To set the trust store the following options are available.
</p><pre class="verbatim">--with-default-trust-store-file
--with-default-trust-store-dir
--with-default-trust-store-pkcs11

</pre><p>The first option is used to set a PEM file which contains a list of trusted certificates,
while the second will read all certificates in the given path. The recommended option is
the last, which allows to use a PKCS #11 trust policy module. That module not only
provides the trusted certificates, but allows the categorization of them using purpose,
e.g., CAs can be restricted for e-mail usage only, or administrative restrictions of CAs, for
examples by restricting a CA to only issue certificates for a given DNS domain using NameConstraints.
A publicly available PKCS #11 trust module is p11-kit&rsquo;s trust module<a name="DOCF2" href="#FOOT2"><sup>2</sup></a>.
</p>
<hr>
<a name="Document-overview"></a>
<div class="header">
<p>
Previous: <a href="#Installing-for-a-software-distribution" accesskey="p" rel="prev">Installing for a software distribution</a>, Up: <a href="#Introduction-to-GnuTLS" accesskey="u" rel="up">Introduction to GnuTLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Overview"></a>
<h3 class="section">2.3 Overview</h3>
<p>In this document we present an overview of the supported security protocols in <a href="#Introduction-to-TLS">Introduction to TLS</a>, and 
continue by providing more information on the certificate authentication in <a href="#Certificate-authentication">Certificate authentication</a>,
and shared-key as well anonymous authentication in <a href="#Shared_002dkey-and-anonymous-authentication">Shared-key and anonymous authentication</a>. We
elaborate on certificate authentication by demonstrating advanced usage of the API in <a href="#More-on-certificate-authentication">More on certificate authentication</a>.
The core of the TLS library is presented in <a href="#How-to-use-GnuTLS-in-applications">How to use GnuTLS in applications</a> and example
applications are listed in <a href="#GnuTLS-application-examples">GnuTLS application examples</a>.
In <a href="#Other-included-programs">Other included programs</a> the usage of few included programs that
may assist debugging is presented. The last chapter is <a href="#Internal-architecture-of-GnuTLS">Internal architecture of GnuTLS</a> that
provides a short introduction to GnuTLS&rsquo; internal architecture.
</p>
<hr>
<a name="Introduction-to-TLS"></a>
<div class="header">
<p>
Next: <a href="#Authentication-methods" accesskey="n" rel="next">Authentication methods</a>, Previous: <a href="#Introduction-to-GnuTLS" accesskey="p" rel="prev">Introduction to GnuTLS</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Introduction-to-TLS-and-DTLS"></a>
<h2 class="chapter">3 Introduction to <acronym>TLS</acronym> and <acronym>DTLS</acronym></h2>

<p><acronym>TLS</acronym> stands for &ldquo;Transport Layer Security&rdquo; and is the
successor of SSL, the Secure Sockets Layer protocol [<em>SSL3</em>]
designed by Netscape.  <acronym>TLS</acronym> is an Internet protocol, defined
by <acronym>IETF</acronym><a name="DOCF3" href="#FOOT3"><sup>3</sup></a>, described in [<em>RFC5246</em>].  
The protocol provides
confidentiality, and authentication layers over any reliable transport
layer.  The description, above, refers to <acronym>TLS</acronym> 1.0 but applies
to all other TLS versions as the differences between the protocols are not major.  
</p>
<p>The <acronym>DTLS</acronym> protocol, or &ldquo;Datagram <acronym>TLS</acronym>&rdquo; [<em>RFC4347</em>] is a
protocol with identical goals as <acronym>TLS</acronym>, but can operate
under unreliable transport layers such as <acronym>UDP</acronym>. The
discussions below apply to this protocol as well, except when
noted otherwise.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#TLS-layers" accesskey="1">TLS layers</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#The-transport-layer" accesskey="2">The transport layer</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#The-TLS-record-protocol" accesskey="3">The TLS record protocol</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#The-TLS-Alert-Protocol" accesskey="4">The TLS Alert Protocol</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#The-TLS-Handshake-Protocol" accesskey="5">The TLS Handshake Protocol</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#TLS-Extensions" accesskey="6">TLS Extensions</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#How-to-use-TLS-in-application-protocols" accesskey="7">How to use TLS in application protocols</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#On-SSL-2-and-older-protocols" accesskey="8">On SSL 2 and older protocols</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="TLS-layers"></a>
<div class="header">
<p>
Next: <a href="#The-transport-layer" accesskey="n" rel="next">The transport layer</a>, Up: <a href="#Introduction-to-TLS" accesskey="u" rel="up">Introduction to TLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="TLS-Layers"></a>
<h3 class="section">3.1 TLS Layers</h3>
<a name="index-TLS-layers"></a>

<p><acronym>TLS</acronym> is a layered protocol, and consists of the record
protocol, the handshake protocol and the alert protocol. The record
protocol is to serve all other protocols and is above the transport
layer.  The record protocol offers symmetric encryption, data
authenticity, and optionally compression.
The alert protocol offers some signaling to the other protocols. It
can help informing the peer for the cause of failures and other error
conditions.  See <a href="#The-Alert-Protocol">The Alert Protocol</a>, for more information.  The
alert protocol is above the record protocol.
</p>
<p>The handshake protocol is responsible for the security parameters&rsquo;
negotiation, the initial key exchange and authentication.  
See <a href="#The-Handshake-Protocol">The Handshake Protocol</a>, for more information about the handshake
protocol.  The protocol layering in TLS is shown in <a href="#fig_002dtls_002dlayers">Figure 3.1</a>.
</p>
<div class="float"><a name="fig_002dtls_002dlayers"></a>
<img src="gnutls-layers.png" alt="gnutls-layers">

<div class="float-caption"><p><strong>Figure 3.1: </strong>The TLS protocol layers.</p></div></div>
<hr>
<a name="The-transport-layer"></a>
<div class="header">
<p>
Next: <a href="#The-TLS-record-protocol" accesskey="n" rel="next">The TLS record protocol</a>, Previous: <a href="#TLS-layers" accesskey="p" rel="prev">TLS layers</a>, Up: <a href="#Introduction-to-TLS" accesskey="u" rel="up">Introduction to TLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="The-Transport-Layer"></a>
<h3 class="section">3.2 The Transport Layer</h3>
<a name="index-transport-protocol"></a>
<a name="index-transport-layer"></a>

<p><acronym>TLS</acronym> is not limited to any transport layer and can be used
above any transport layer, as long as it is a reliable one.  <acronym>DTLS</acronym>
can be used over reliable and unreliable transport layers.
<acronym>GnuTLS</acronym> supports TCP and UDP layers transparently using
the Berkeley sockets API. However, any transport layer can be used
by providing callbacks for <acronym>GnuTLS</acronym> to access the transport layer 
(for details see <a href="#Setting-up-the-transport-layer">Setting up the transport layer</a>).
</p>
<hr>
<a name="The-TLS-record-protocol"></a>
<div class="header">
<p>
Next: <a href="#The-TLS-Alert-Protocol" accesskey="n" rel="next">The TLS Alert Protocol</a>, Previous: <a href="#The-transport-layer" accesskey="p" rel="prev">The transport layer</a>, Up: <a href="#Introduction-to-TLS" accesskey="u" rel="up">Introduction to TLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="The-TLS-record-protocol-1"></a>
<h3 class="section">3.3 The TLS record protocol</h3>
<a name="index-record-protocol"></a>

<p>The record protocol is the secure communications provider. Its purpose
is to encrypt, authenticate and &mdash;optionally&mdash; compress packets.
The record layer functions can be called at any time after
the handshake process is finished, when there is need to receive
or send data. In <acronym>DTLS</acronym> however, due to re-transmission
timers used in the handshake out-of-order handshake data might
be received for some time (maximum 60 seconds) after the handshake
process is finished. 
</p>
<p>The functions to access the record protocol are limited to send
and receive functions, which might, given 
the importance of this protocol in <acronym>TLS</acronym>, seem awkward.  This is because 
the record protocol&rsquo;s parameters are all set by the handshake protocol.
The record protocol initially starts with NULL parameters, which means
no encryption, and no MAC is used. Encryption and authentication begin
just after the handshake protocol has finished.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Encryption-algorithms-used-in-the-record-layer" accesskey="1">Encryption algorithms used in the record layer</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Compression-algorithms-used-in-the-record-layer" accesskey="2">Compression algorithms used in the record layer</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Weaknesses-and-countermeasures" accesskey="3">Weaknesses and countermeasures</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#On-Record-Padding" accesskey="4">On Record Padding</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Encryption-algorithms-used-in-the-record-layer"></a>
<div class="header">
<p>
Next: <a href="#Compression-algorithms-used-in-the-record-layer" accesskey="n" rel="next">Compression algorithms used in the record layer</a>, Up: <a href="#The-TLS-record-protocol" accesskey="u" rel="up">The TLS record protocol</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Encryption-algorithms-used-in-the-record-layer-1"></a>
<h4 class="subsection">3.3.1 Encryption algorithms used in the record layer</h4>
<a name="index-symmetric-encryption-algorithms"></a>

<p>Confidentiality in the record layer is achieved by using symmetric
block encryption algorithms like <code>3DES</code>, <code>AES</code>
or stream algorithms like <code>ARCFOUR_128</code>.
 Ciphers are encryption algorithms that use a single, secret,
key to encrypt and decrypt data. Block algorithms in CBC mode also provide
protection against statistical analysis of the data.  Thus, if you&rsquo;re
using the <acronym>TLS</acronym> protocol, a random number of blocks will be
appended to data, to prevent eavesdroppers from guessing the actual
data size.
</p>
<p>The supported in <acronym>GnuTLS</acronym> ciphers and MAC algorithms are shown in <a href="#tab_003aciphers">Table 3.1</a> and
<a href="#tab_003amacs">Table 3.2</a>.
</p>
<div class="float"><a name="tab_003aciphers"></a>
<table>
<thead><tr><th width="20%">Algorithm</th><th width="70%">Description</th></tr></thead>
<tr><td width="20%">AES_CBC</td><td width="70%">AES or RIJNDAEL is the block cipher algorithm that replaces the old
DES algorithm.  Has 128 bits block size and is used in CBC mode.</td></tr>
<tr><td width="20%">AES_GCM</td><td width="70%">This is the AES algorithm in the authenticated encryption GCM mode.
This mode combines message authentication and encryption and can
be extremely fast on CPUs that support hardware acceleration.</td></tr>
<tr><td width="20%">AES_CCM</td><td width="70%">This is the AES algorithm in the authenticated encryption CCM mode.
This mode combines message authentication and encryption and is
often used by systems without AES or GCM acceleration support.</td></tr>
<tr><td width="20%">AES_CCM_8</td><td width="70%">This is the AES algorithm in the authenticated encryption CCM mode
with a truncated to 64-bit authentication tag. This mode is for
communication with restricted systems.</td></tr>
<tr><td width="20%">CAMELLIA_CBC</td><td width="70%">This is an 128-bit block cipher developed by Mitsubishi and NTT. It
is one of the approved ciphers of the European NESSIE and Japanese
CRYPTREC projects.</td></tr>
<tr><td width="20%">CHACHA20_POLY1305</td><td width="70%">CHACHA20-POLY1305 is an authenticated encryption algorithm based on CHACHA20 cipher and
POLY1305 MAC. CHACHA20 is a refinement of SALSA20 algorithm, an approved cipher by
the European ESTREAM project. POLY1305 is Wegman-Carter, one-time authenticator. The
combination provides a fast stream cipher suitable for systems where a hardware AES
accelerator is not available.</td></tr>
<tr><td width="20%">3DES_CBC</td><td width="70%">This is the DES block cipher algorithm used with triple
encryption (EDE). Has 64 bits block size and is used in CBC mode.</td></tr>
<tr><td width="20%">ARCFOUR_128</td><td width="70%">ARCFOUR-128 is a compatible algorithm with RSA&rsquo;s RC4 algorithm, which is considered to be a trade
secret. It is a fast cipher but considered weak today, and thus it is not enabled by default.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 3.1: </strong>Supported ciphers in TLS.</p></div></div>

<div class="float"><a name="tab_003amacs"></a>
<table>
<thead><tr><th width="20%">Algorithm</th><th width="70%">Description</th></tr></thead>
<tr><td width="20%">MAC_MD5</td><td width="70%">This is an HMAC based on MD5 a cryptographic hash algorithm designed 
by Ron Rivest. Outputs 128 bits of data.</td></tr>
<tr><td width="20%">MAC_SHA1</td><td width="70%">An HMAC based on the SHA1 cryptographic hash algorithm 
designed by NSA. Outputs 160 bits of data.</td></tr>
<tr><td width="20%">MAC_SHA256</td><td width="70%">An HMAC based on SHA2-256. Outputs 256 bits of data.</td></tr>
<tr><td width="20%">MAC_SHA384</td><td width="70%">An HMAC based on SHA2-384. Outputs 384 bits of data.</td></tr>
<tr><td width="20%">MAC_AEAD</td><td width="70%">This indicates that an authenticated encryption algorithm, such as
GCM, is in use.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 3.2: </strong>Supported MAC algorithms in TLS.</p></div></div>

<hr>
<a name="Compression-algorithms-used-in-the-record-layer"></a>
<div class="header">
<p>
Next: <a href="#Weaknesses-and-countermeasures" accesskey="n" rel="next">Weaknesses and countermeasures</a>, Previous: <a href="#Encryption-algorithms-used-in-the-record-layer" accesskey="p" rel="prev">Encryption algorithms used in the record layer</a>, Up: <a href="#The-TLS-record-protocol" accesskey="u" rel="up">The TLS record protocol</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Compression-algorithms-used-in-the-record-layer-1"></a>
<h4 class="subsection">3.3.2 Compression algorithms used in the record layer</h4>
<a name="index-compression-algorithms"></a>

<p>The TLS record layer also supports compression.  The algorithms
implemented in <acronym>GnuTLS</acronym> can be found in the table below.
The included algorithms perform really good when text, or other
compressible data are to be transferred, but offer nothing on already
compressed data, such as compressed images, zipped archives etc.
These compression algorithms, may be useful in high bandwidth TLS
tunnels, and in cases where network usage has to be minimized. It
should be noted however that compression increases latency.
</p>
<p>The record layer compression in <acronym>GnuTLS</acronym> is implemented based
on [<em>RFC3749</em>]. The supported algorithms are shown below.
</p>
<div class="float"><a name="gnutls_005fcompression_005fmethod_005ft"></a>


<dl compact="compact">
<dt><code>GNUTLS_COMP_UNKNOWN</code></dt>
<dd><p>Unknown compression method.
</p></dd>
<dt><code>GNUTLS_COMP_NULL</code></dt>
<dd><p>The NULL compression method (no compression).
</p></dd>
<dt><code>GNUTLS_COMP_DEFLATE</code></dt>
<dd><p>The DEFLATE compression method from zlib.
</p></dd>
<dt><code>GNUTLS_COMP_ZLIB</code></dt>
<dd><p>Same as <code>GNUTLS_COMP_DEFLATE</code> .
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 3.2: </strong>Supported compression algorithms</p></div></div>
<p>Note that compression enables attacks such as traffic analysis, or even
plaintext recovery under certain circumstances. To avoid some of these
attacks GnuTLS allows each record to be compressed independently (i.e.,
stateless compression), by using the &quot;%STATELESS_COMPRESSION&quot; priority string,
in order to be used in cases where the attacker controlled data are
pt in separate records.
</p>
<hr>
<a name="Weaknesses-and-countermeasures"></a>
<div class="header">
<p>
Next: <a href="#On-Record-Padding" accesskey="n" rel="next">On Record Padding</a>, Previous: <a href="#Compression-algorithms-used-in-the-record-layer" accesskey="p" rel="prev">Compression algorithms used in the record layer</a>, Up: <a href="#The-TLS-record-protocol" accesskey="u" rel="up">The TLS record protocol</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Weaknesses-and-countermeasures-1"></a>
<h4 class="subsection">3.3.3 Weaknesses and countermeasures</h4>

<p>Some weaknesses that may affect the security of the record layer have
been found in <acronym>TLS</acronym> 1.0 protocol. These weaknesses can be
exploited by active attackers, and exploit the facts that
</p>
<ol>
<li> <acronym>TLS</acronym> has separate alerts for &ldquo;decryption_failed&rdquo; and
&ldquo;bad_record_mac&rdquo;

</li><li> The decryption failure reason can be detected by timing the response
time.

</li><li> The IV for CBC encrypted packets is the last block of the previous
encrypted packet.

</li></ol>

<p>Those weaknesses were solved in <acronym>TLS</acronym> 1.1 [<em>RFC4346</em>]
which is implemented in <acronym>GnuTLS</acronym>. For this reason we suggest
to always negotiate the highest supported TLS version with the 
peer<a name="DOCF4" href="#FOOT4"><sup>4</sup></a>.
For a detailed discussion of the issues see the archives of the TLS 
Working Group mailing list and [<em>CBCATT</em>].
</p>
<hr>
<a name="On-Record-Padding"></a>
<div class="header">
<p>
Previous: <a href="#Weaknesses-and-countermeasures" accesskey="p" rel="prev">Weaknesses and countermeasures</a>, Up: <a href="#The-TLS-record-protocol" accesskey="u" rel="up">The TLS record protocol</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="On-record-padding"></a>
<h4 class="subsection">3.3.4 On record padding</h4>
<a name="index-record-padding"></a>
<a name="index-bad_005frecord_005fmac"></a>

<p>The TLS protocol allows for extra padding of records in CBC ciphers, to prevent
statistical analysis based on the length of exchanged messages (see [<em>RFC5246</em>] section 6.2.3.2).  
GnuTLS appears to be one of few implementations that take advantage of this feature: 
the user can provide some plaintext data with a range of lengths she wishes to hide,
and GnuTLS adds extra padding to make sure the attacker cannot tell the real plaintext
length is in a range smaller than the user-provided one.
Use <a href="#gnutls_005frecord_005fsend_005frange">gnutls_record_send_range</a> to send length-hidden messages and
<a href="#gnutls_005frecord_005fcan_005fuse_005flength_005fhiding">gnutls_record_can_use_length_hiding</a> to check whether the current
session supports length hiding. Using the standard <a href="#gnutls_005frecord_005fsend">gnutls_record_send</a>
will only add minimal padding.
</p>
<p>The TLS implementation in the Symbian operating system, frequently
used by Nokia and Sony-Ericsson mobile phones, cannot handle
non-minimal record padding.  What happens when one of these clients
handshake with a GnuTLS server is that the client will fail to compute
the correct MAC for the record.  The client sends a TLS alert
(<code>bad_record_mac</code>) and disconnects.  Typically this will result
in error messages such as &rsquo;A TLS fatal alert has been received&rsquo;, &rsquo;Bad
record MAC&rsquo;, or both, on the GnuTLS server side.
</p>
<p>If compatibility with such devices is a concern, not sending length-hidden messages
solves the problem by using minimal padding.
</p>
<p>If you implement an application that has a configuration file, we
recommend that you make it possible for users or administrators to
specify a GnuTLS protocol priority string, which is used by your
application via <a href="#gnutls_005fpriority_005fset">gnutls_priority_set</a>.  To allow the best
flexibility, make it possible to have a different priority string for
different incoming IP addresses.
</p>

<hr>
<a name="The-TLS-Alert-Protocol"></a>
<div class="header">
<p>
Next: <a href="#The-TLS-Handshake-Protocol" accesskey="n" rel="next">The TLS Handshake Protocol</a>, Previous: <a href="#The-TLS-record-protocol" accesskey="p" rel="prev">The TLS record protocol</a>, Up: <a href="#Introduction-to-TLS" accesskey="u" rel="up">Introduction to TLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="The-TLS-alert-protocol"></a>
<h3 class="section">3.4 The TLS alert protocol</h3>
<a name="The-Alert-Protocol"></a><a name="index-alert-protocol"></a>

<p>The alert protocol is there to allow signals to be sent between peers.
These signals are mostly used to inform the peer about the cause of a
protocol failure. Some of these signals are used internally by the
protocol and the application protocol does not have to cope with them
(e.g. <code>GNUTLS_A_CLOSE_NOTIFY</code>), and others refer to the
application protocol solely (e.g. <code>GNUTLS_A_USER_CANCELLED</code>).  An
alert signal includes a level indication which may be either fatal or
warning. Fatal alerts always terminate the current connection, and
prevent future re-negotiations using the current session ID. All alert
messages are summarized in the table below.
</p>
<p>The alert messages are protected by the record protocol, thus the
information that is included does not leak. You must take extreme care
for the alert information not to leak to a possible attacker, via
public log files etc. 
</p>
<table>
<tr><td><a name="tab_003aalerts"></a></td></tr>
<thead><tr><th width="55%">Alert</th><th width="10%">ID</th><th width="30%">Description</th></tr></thead>
<tr><td width="55%">GNUTLS_A_CLOSE_NOTIFY</td><td width="10%">0</td><td width="30%">Close notify</td></tr>
<tr><td width="55%">GNUTLS_A_UNEXPECTED_MESSAGE</td><td width="10%">10</td><td width="30%">Unexpected message</td></tr>
<tr><td width="55%">GNUTLS_A_BAD_RECORD_MAC</td><td width="10%">20</td><td width="30%">Bad record MAC</td></tr>
<tr><td width="55%">GNUTLS_A_DECRYPTION_FAILED</td><td width="10%">21</td><td width="30%">Decryption failed</td></tr>
<tr><td width="55%">GNUTLS_A_RECORD_OVERFLOW</td><td width="10%">22</td><td width="30%">Record overflow</td></tr>
<tr><td width="55%">GNUTLS_A_DECOMPRESSION_FAILURE</td><td width="10%">30</td><td width="30%">Decompression failed</td></tr>
<tr><td width="55%">GNUTLS_A_HANDSHAKE_FAILURE</td><td width="10%">40</td><td width="30%">Handshake failed</td></tr>
<tr><td width="55%">GNUTLS_A_SSL3_NO_CERTIFICATE</td><td width="10%">41</td><td width="30%">No certificate (SSL 3.0)</td></tr>
<tr><td width="55%">GNUTLS_A_BAD_CERTIFICATE</td><td width="10%">42</td><td width="30%">Certificate is bad</td></tr>
<tr><td width="55%">GNUTLS_A_UNSUPPORTED_CERTIFICATE</td><td width="10%">43</td><td width="30%">Certificate is not supported</td></tr>
<tr><td width="55%">GNUTLS_A_CERTIFICATE_REVOKED</td><td width="10%">44</td><td width="30%">Certificate was revoked</td></tr>
<tr><td width="55%">GNUTLS_A_CERTIFICATE_EXPIRED</td><td width="10%">45</td><td width="30%">Certificate is expired</td></tr>
<tr><td width="55%">GNUTLS_A_CERTIFICATE_UNKNOWN</td><td width="10%">46</td><td width="30%">Unknown certificate</td></tr>
<tr><td width="55%">GNUTLS_A_ILLEGAL_PARAMETER</td><td width="10%">47</td><td width="30%">Illegal parameter</td></tr>
<tr><td width="55%">GNUTLS_A_UNKNOWN_CA</td><td width="10%">48</td><td width="30%">CA is unknown</td></tr>
<tr><td width="55%">GNUTLS_A_ACCESS_DENIED</td><td width="10%">49</td><td width="30%">Access was denied</td></tr>
<tr><td width="55%">GNUTLS_A_DECODE_ERROR</td><td width="10%">50</td><td width="30%">Decode error</td></tr>
<tr><td width="55%">GNUTLS_A_DECRYPT_ERROR</td><td width="10%">51</td><td width="30%">Decrypt error</td></tr>
<tr><td width="55%">GNUTLS_A_EXPORT_RESTRICTION</td><td width="10%">60</td><td width="30%">Export restriction</td></tr>
<tr><td width="55%">GNUTLS_A_PROTOCOL_VERSION</td><td width="10%">70</td><td width="30%">Error in protocol version</td></tr>
<tr><td width="55%">GNUTLS_A_INSUFFICIENT_SECURITY</td><td width="10%">71</td><td width="30%">Insufficient security</td></tr>
<tr><td width="55%">GNUTLS_A_INTERNAL_ERROR</td><td width="10%">80</td><td width="30%">Internal error</td></tr>
<tr><td width="55%">GNUTLS_A_INAPPROPRIATE_FALLBACK</td><td width="10%">86</td><td width="30%">Inappropriate fallback</td></tr>
<tr><td width="55%">GNUTLS_A_USER_CANCELED</td><td width="10%">90</td><td width="30%">User canceled</td></tr>
<tr><td width="55%">GNUTLS_A_NO_RENEGOTIATION</td><td width="10%">100</td><td width="30%">No renegotiation is allowed</td></tr>
<tr><td width="55%">GNUTLS_A_UNSUPPORTED_EXTENSION</td><td width="10%">110</td><td width="30%">An unsupported extension was sent</td></tr>
<tr><td width="55%">GNUTLS_A_CERTIFICATE_UNOBTAINABLE</td><td width="10%">111</td><td width="30%">Could not retrieve the specified certificate</td></tr>
<tr><td width="55%">GNUTLS_A_UNRECOGNIZED_NAME</td><td width="10%">112</td><td width="30%">The server name sent was not recognized</td></tr>
<tr><td width="55%">GNUTLS_A_UNKNOWN_PSK_IDENTITY</td><td width="10%">115</td><td width="30%">The SRP/PSK username is missing or not known</td></tr>
<tr><td width="55%">GNUTLS_A_NO_APPLICATION_PROTOCOL</td><td width="10%">120</td><td width="30%">No supported application protocol could be negotiated</td></tr>
</table>

<hr>
<a name="The-TLS-Handshake-Protocol"></a>
<div class="header">
<p>
Next: <a href="#TLS-Extensions" accesskey="n" rel="next">TLS Extensions</a>, Previous: <a href="#The-TLS-Alert-Protocol" accesskey="p" rel="prev">The TLS Alert Protocol</a>, Up: <a href="#Introduction-to-TLS" accesskey="u" rel="up">Introduction to TLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="The-TLS-handshake-protocol"></a>
<h3 class="section">3.5 The TLS handshake protocol</h3>
<a name="The-Handshake-Protocol"></a><a name="index-handshake-protocol"></a>

<p>The handshake protocol is responsible for the ciphersuite negotiation,
the initial key exchange, and the authentication of the two peers.
This is fully controlled by the application layer, thus your program
has to set up the required parameters. The main handshake function
is <a href="#gnutls_005fhandshake">gnutls_handshake</a>. In the next paragraphs we elaborate on 
the handshake protocol, i.e., the ciphersuite negotiation.
</p>

<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#TLS-Cipher-Suites" accesskey="1">TLS Cipher Suites</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">TLS session parameters.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Authentication" accesskey="2">Authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">TLS authentication.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Client-Authentication" accesskey="3">Client Authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Requesting a certificate from the client.
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Resuming-Sessions" accesskey="4">Resuming Sessions</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Reusing previously established keys.
</td></tr>
</table>


<hr>
<a name="TLS-Cipher-Suites"></a>
<div class="header">
<p>
Next: <a href="#Authentication" accesskey="n" rel="next">Authentication</a>, Up: <a href="#The-TLS-Handshake-Protocol" accesskey="u" rel="up">The TLS Handshake Protocol</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="TLS-ciphersuites"></a>
<h4 class="subsection">3.5.1 TLS ciphersuites</h4>

<p>The handshake protocol of <acronym>TLS</acronym> negotiates cipher suites of
a special form illustrated by the <code>TLS_DHE_RSA_WITH_3DES_CBC_SHA</code> cipher suite name.  A typical cipher
suite contains these parameters:
</p>
<ul>
<li> The key exchange algorithm.
<code>DHE_RSA</code> in the example.

</li><li> The Symmetric encryption algorithm and mode
<code>3DES_CBC</code> in this example.

</li><li> The MAC<a name="DOCF5" href="#FOOT5"><sup>5</sup></a> algorithm used for authentication.
<code>MAC_SHA</code> is used in the above example.

</li></ul>

<p>The cipher suite negotiated in the handshake protocol will affect the
record protocol, by enabling encryption and data authentication.  Note
that you should not over rely on <acronym>TLS</acronym> to negotiate the
strongest available cipher suite. Do not enable ciphers and algorithms
that you consider weak.
</p>
<p>All the supported ciphersuites are listed in <a href="#ciphersuites">ciphersuites</a>.
</p>
<hr>
<a name="Authentication"></a>
<div class="header">
<p>
Next: <a href="#Client-Authentication" accesskey="n" rel="next">Client Authentication</a>, Previous: <a href="#TLS-Cipher-Suites" accesskey="p" rel="prev">TLS Cipher Suites</a>, Up: <a href="#The-TLS-Handshake-Protocol" accesskey="u" rel="up">The TLS Handshake Protocol</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Authentication-1"></a>
<h4 class="subsection">3.5.2 Authentication</h4>

<p>The key exchange algorithms of the <acronym>TLS</acronym> protocol offer
authentication, which is a prerequisite for a secure connection. 
The available authentication methods in <acronym>GnuTLS</acronym> follow.
</p>
<ul>
<li> Certificate authentication: Authenticated key exchange using public key infrastructure and certificates (X.509 or OpenPGP).
</li><li> <acronym>SRP</acronym> authentication: Authenticated key exchange using a password.
</li><li> <acronym>PSK</acronym> authentication: Authenticated key exchange using a pre-shared key.
</li><li> Anonymous authentication: Key exchange without peer authentication.

</li></ul>

<hr>
<a name="Client-Authentication"></a>
<div class="header">
<p>
Next: <a href="#Resuming-Sessions" accesskey="n" rel="next">Resuming Sessions</a>, Previous: <a href="#Authentication" accesskey="p" rel="prev">Authentication</a>, Up: <a href="#The-TLS-Handshake-Protocol" accesskey="u" rel="up">The TLS Handshake Protocol</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Client-authentication"></a>
<h4 class="subsection">3.5.3 Client authentication</h4>
<a name="index-client-certificate-authentication"></a>

<p>In the case of ciphersuites that use certificate authentication, the
authentication of the client is optional in <acronym>TLS</acronym>.  A server
may request a certificate from the client using the
<a href="#gnutls_005fcertificate_005fserver_005fset_005frequest">gnutls_certificate_server_set_request</a> function. We elaborate 
in <a href="#Certificate-credentials">Certificate credentials</a>.
</p>
<hr>
<a name="Resuming-Sessions"></a>
<div class="header">
<p>
Previous: <a href="#Client-Authentication" accesskey="p" rel="prev">Client Authentication</a>, Up: <a href="#The-TLS-Handshake-Protocol" accesskey="u" rel="up">The TLS Handshake Protocol</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Resuming-sessions"></a>
<h4 class="subsection">3.5.4 Resuming sessions</h4>
<a name="resume"></a><a name="index-resuming-sessions"></a>
<a name="index-session-resumption"></a>

<p>The TLS handshake process performs expensive calculations
and a busy server might easily be put under load. To 
reduce the load, session resumption may be used. This
is a feature of the <acronym>TLS</acronym> protocol which allows a
client to connect to a server after a successful handshake, without
the expensive calculations.  This is achieved by re-using the previously
established keys, meaning the server needs to store the state of established
connections (unless session tickets are used &ndash; <a href="#Session-tickets">Session tickets</a>).
</p>
<p>Session resumption is an integral part of <acronym>GnuTLS</acronym>, and 
<a href="#Session-resumption">Session resumption</a>, <a href="#ex_002dresume_002dclient">ex-resume-client</a> illustrate typical 
uses of it.
</p>
<hr>
<a name="TLS-Extensions"></a>
<div class="header">
<p>
Next: <a href="#How-to-use-TLS-in-application-protocols" accesskey="n" rel="next">How to use TLS in application protocols</a>, Previous: <a href="#The-TLS-Handshake-Protocol" accesskey="p" rel="prev">The TLS Handshake Protocol</a>, Up: <a href="#Introduction-to-TLS" accesskey="u" rel="up">Introduction to TLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="TLS-extensions"></a>
<h3 class="section">3.6 TLS extensions</h3>
<a name="index-TLS-extensions"></a>

<p>A number of extensions to the <acronym>TLS</acronym> protocol have been
proposed mainly in [<em>TLSEXT</em>]. The extensions supported
in <acronym>GnuTLS</acronym> are discussed in the subsections that follow.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Maximum-fragment-length-negotiation" accesskey="1">Maximum fragment length negotiation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Server-name-indication" accesskey="2">Server name indication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Session-tickets" accesskey="3">Session tickets</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#HeartBeat" accesskey="4">HeartBeat</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Safe-renegotiation" accesskey="5">Safe renegotiation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OCSP-status-request" accesskey="6">OCSP status request</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#SRTP" accesskey="7">SRTP</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Application-Layer-Protocol-Negotiation-_0028ALPN_0029" accesskey="8">Application Layer Protocol Negotiation (ALPN)</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Extensions-and-Supplemental-Data" accesskey="9">Extensions and Supplemental Data</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Maximum-fragment-length-negotiation"></a>
<div class="header">
<p>
Next: <a href="#Server-name-indication" accesskey="n" rel="next">Server name indication</a>, Up: <a href="#TLS-Extensions" accesskey="u" rel="up">TLS Extensions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Maximum-fragment-length-negotiation-1"></a>
<h4 class="subsection">3.6.1 Maximum fragment length negotiation</h4>
<a name="index-TLS-extensions-1"></a>
<a name="index-maximum-fragment-length"></a>

<p>This extension allows a <acronym>TLS</acronym> implementation to negotiate a
smaller value for record packet maximum length. This extension may be
useful to clients with constrained capabilities. The functions shown
below can be used to control this extension.
</p>
<dl compact="compact">
<dt><code><var>size_t</var> <a href="#gnutls_005frecord_005fget_005fmax_005fsize">gnutls_record_get_max_size</a> (gnutls_session_t <var>session</var>)</code></dt>
<dt><code><var>ssize_t</var> <a href="#gnutls_005frecord_005fset_005fmax_005fsize">gnutls_record_set_max_size</a> (gnutls_session_t <var>session</var>, size_t <var>size</var>)</code></dt>
</dl>

<hr>
<a name="Server-name-indication"></a>
<div class="header">
<p>
Next: <a href="#Session-tickets" accesskey="n" rel="next">Session tickets</a>, Previous: <a href="#Maximum-fragment-length-negotiation" accesskey="p" rel="prev">Maximum fragment length negotiation</a>, Up: <a href="#TLS-Extensions" accesskey="u" rel="up">TLS Extensions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Server-name-indication-1"></a>
<h4 class="subsection">3.6.2 Server name indication</h4>
<a name="serverind"></a><a name="index-TLS-extensions-2"></a>
<a name="index-server-name-indication"></a>

<p>A common problem in <acronym>HTTPS</acronym> servers is the fact that the
<acronym>TLS</acronym> protocol is not aware of the hostname that a client
connects to, when the handshake procedure begins. For that reason the
<acronym>TLS</acronym> server has no way to know which certificate to send.
</p>
<p>This extension solves that problem within the <acronym>TLS</acronym> protocol,
and allows a client to send the HTTP hostname before the handshake
begins within the first handshake packet.  The functions
<a href="#gnutls_005fserver_005fname_005fset">gnutls_server_name_set</a> and <a href="#gnutls_005fserver_005fname_005fget">gnutls_server_name_get</a> can be
used to enable this extension, or to retrieve the name sent by a
client.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fserver_005fname_005fset">gnutls_server_name_set</a> (gnutls_session_t <var>session</var>, gnutls_server_name_type_t <var>type</var>, const void * <var>name</var>, size_t <var>name_length</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fserver_005fname_005fget">gnutls_server_name_get</a> (gnutls_session_t <var>session</var>, void * <var>data</var>, size_t * <var>data_length</var>, unsigned int * <var>type</var>, unsigned int <var>indx</var>)</code></dt>
</dl>

<hr>
<a name="Session-tickets"></a>
<div class="header">
<p>
Next: <a href="#HeartBeat" accesskey="n" rel="next">HeartBeat</a>, Previous: <a href="#Server-name-indication" accesskey="p" rel="prev">Server name indication</a>, Up: <a href="#TLS-Extensions" accesskey="u" rel="up">TLS Extensions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Session-tickets-1"></a>
<h4 class="subsection">3.6.3 Session tickets</h4>
<a name="index-TLS-extensions-3"></a>
<a name="index-session-tickets"></a>
<a name="index-tickets"></a>

<p>To resume a TLS session, the server normally stores session parameters.  This
complicates deployment, and can be avoided by delegating the storage
to the client. Because session parameters are sensitive they are encrypted
and authenticated with a key only known to the server and then sent to the
client. The Session Tickets extension is described in RFC 5077 [<em>TLSTKT</em>].
</p>
<p>A disadvantage of session tickets is that they eliminate the effects of
forward secrecy when a server uses the same key for long time. That is,
the secrecy of all sessions on a server using tickets depends on the ticket
key being kept secret. For that reason server keys should be rotated and discarded
regularly.
</p>
<p>Since version 3.1.3 GnuTLS clients transparently support session tickets,
unless forward secrecy is explicitly requested (with the PFS priority string).
</p>
<hr>
<a name="HeartBeat"></a>
<div class="header">
<p>
Next: <a href="#Safe-renegotiation" accesskey="n" rel="next">Safe renegotiation</a>, Previous: <a href="#Session-tickets" accesskey="p" rel="prev">Session tickets</a>, Up: <a href="#TLS-Extensions" accesskey="u" rel="up">TLS Extensions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="HeartBeat-1"></a>
<h4 class="subsection">3.6.4 HeartBeat</h4>
<a name="index-TLS-extensions-4"></a>
<a name="index-heartbeat"></a>

<p>This is a TLS extension that allows to ping and receive confirmation from the peer,
and is described in [<em>RFC6520</em>]. The extension is disabled by default and
<a href="#gnutls_005fheartbeat_005fenable">gnutls_heartbeat_enable</a> can be used to enable it. A policy
may be negotiated to only allow sending heartbeat messages or sending and receiving.
The current session policy can be checked with <a href="#gnutls_005fheartbeat_005fallowed">gnutls_heartbeat_allowed</a>. 
The requests coming from the peer result to <code>GNUTLS_E_HEARTBEAT_PING_RECEIVED</code>
being returned from the receive function. Ping requests to peer can be send via
<a href="#gnutls_005fheartbeat_005fping">gnutls_heartbeat_ping</a>. 
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fheartbeat_005fallowed">gnutls_heartbeat_allowed</a> (gnutls_session_t <var>session</var>, unsigned int <var>type</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fheartbeat_005fenable">gnutls_heartbeat_enable</a> (gnutls_session_t <var>session</var>, unsigned int <var>type</var>)</code></dt>
</dl>

<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fheartbeat_005fping">gnutls_heartbeat_ping</a> (gnutls_session_t <var>session</var>, size_t <var>data_size</var>, unsigned int <var>max_tries</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fheartbeat_005fpong">gnutls_heartbeat_pong</a> (gnutls_session_t <var>session</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fheartbeat_005fset_005ftimeouts">gnutls_heartbeat_set_timeouts</a> (gnutls_session_t <var>session</var>, unsigned int <var>retrans_timeout</var>, unsigned int <var>total_timeout</var>)</code></dt>
<dt><code><var>unsigned int</var> <a href="#gnutls_005fheartbeat_005fget_005ftimeout">gnutls_heartbeat_get_timeout</a> (gnutls_session_t <var>session</var>)</code></dt>
</dl>

<hr>
<a name="Safe-renegotiation"></a>
<div class="header">
<p>
Next: <a href="#OCSP-status-request" accesskey="n" rel="next">OCSP status request</a>, Previous: <a href="#HeartBeat" accesskey="p" rel="prev">HeartBeat</a>, Up: <a href="#TLS-Extensions" accesskey="u" rel="up">TLS Extensions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Safe-renegotiation-1"></a>
<h4 class="subsection">3.6.5 Safe renegotiation</h4>
<a name="index-renegotiation"></a>
<a name="index-safe-renegotiation"></a>

<p>TLS gives the option to two communicating parties to renegotiate
and update their security parameters. One useful example of this feature
was for a client to initially connect using anonymous negotiation to a
server, and the renegotiate using some authenticated ciphersuite. This occurred
to avoid having the client sending its credentials in the clear.
</p>
<p>However this renegotiation, as initially designed would not ensure that
the party one is renegotiating is the same as the one in the initial negotiation.
For example one server could forward all renegotiation traffic to an other
server who will see this traffic as an initial negotiation attempt.
</p>
<p>This might be seen as a valid design decision, but it seems it was
not widely known or understood, thus today some application protocols use the TLS
renegotiation feature in a manner that enables a malicious server to insert
content of his choice in the beginning of a TLS session.
</p>
<p>The most prominent vulnerability was with HTTPS. There servers request
a renegotiation to enforce an anonymous user to use a certificate in order
to access certain parts of a web site.  The
attack works by having the attacker simulate a client and connect to a
server, with server-only authentication, and send some data intended
to cause harm.  The server will then require renegotiation from him
in order to perform the request. 
When the proper client attempts to contact the server,
the attacker hijacks that connection and forwards traffic to
the initial server that requested renegotiation.  The
attacker will not be able to read the data exchanged between the
client and the server.  However, the server will (incorrectly) assume
that the initial request sent by the attacker was sent by the now authenticated
client.  The result is a prefix plain-text injection attack.
</p>
<p>The above is just one example.  Other vulnerabilities exists that do
not rely on the TLS renegotiation to change the client&rsquo;s authenticated
status (either TLS or application layer).
</p>
<p>While fixing these application protocols and implementations would be
one natural reaction, an extension to TLS has been designed that
cryptographically binds together any renegotiated handshakes with the
initial negotiation.  When the extension is used, the attack is
detected and the session can be terminated.  The extension is
specified in [<em>RFC5746</em>].
</p>
<p>GnuTLS supports the safe renegotiation extension.  The default
behavior is as follows.  Clients will attempt to negotiate the safe
renegotiation extension when talking to servers.  Servers will accept
the extension when presented by clients.  Clients and servers will
permit an initial handshake to complete even when the other side does
not support the safe renegotiation extension.  Clients and servers
will refuse renegotiation attempts when the extension has not been
negotiated.
</p>
<p>Note that permitting clients to connect to servers when the safe
renegotiation extension is not enabled, is open up for attacks.
Changing this default behavior would prevent interoperability against
the majority of deployed servers out there.  We will reconsider this
default behavior in the future when more servers have been upgraded.
Note that it is easy to configure clients to always require the safe
renegotiation extension from servers.
</p>
<p>To modify the default behavior, we have introduced some new priority
strings (see <a href="#Priority-Strings">Priority Strings</a>).  
The <code>%UNSAFE_RENEGOTIATION</code> priority string permits
(re-)handshakes even when the safe renegotiation extension was not
negotiated. The default behavior is <code>%PARTIAL_RENEGOTIATION</code> that will
prevent renegotiation with clients and servers not supporting the
extension. This is secure for servers but leaves clients vulnerable
to some attacks, but this is a trade-off between security and compatibility
with old servers. The <code>%SAFE_RENEGOTIATION</code> priority string makes
clients and servers require the extension for every handshake. The latter
is the most secure option for clients, at the cost of not being able
to connect to legacy servers. Servers will also deny clients that
do not support the extension from connecting.
</p>
<p>It is possible to disable use of the extension completely, in both
clients and servers, by using the <code>%DISABLE_SAFE_RENEGOTIATION</code>
priority string however we strongly recommend you to only do this for
debugging and test purposes.
</p>
<p>The default values if the flags above are not specified are:
</p><dl compact="compact">
<dt><code>Server:</code></dt>
<dd><p>%PARTIAL_RENEGOTIATION
</p>
</dd>
<dt><code>Client:</code></dt>
<dd><p>%PARTIAL_RENEGOTIATION
</p>
</dd>
</dl>

<p>For applications we have introduced a new API related to safe
renegotiation.  The <a href="#gnutls_005fsafe_005frenegotiation_005fstatus">gnutls_safe_renegotiation_status</a> function is
used to check if the extension has been negotiated on a session, and
can be used both by clients and servers.
</p>
<hr>
<a name="OCSP-status-request"></a>
<div class="header">
<p>
Next: <a href="#SRTP" accesskey="n" rel="next">SRTP</a>, Previous: <a href="#Safe-renegotiation" accesskey="p" rel="prev">Safe renegotiation</a>, Up: <a href="#TLS-Extensions" accesskey="u" rel="up">TLS Extensions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OCSP-status-request-1"></a>
<h4 class="subsection">3.6.6 OCSP status request</h4>
<a name="index-OCSP-status-request"></a>
<a name="index-Certificate-status-request"></a>

<p>The Online Certificate Status Protocol (OCSP) is a protocol that allows the
client to verify the server certificate for revocation without messing with
certificate revocation lists. Its drawback is that it requires the client
to connect to the server&rsquo;s CA OCSP server and request the status of the
certificate. This extension however, enables a TLS server to include
its CA OCSP server response in the handshake. That is an HTTPS server
may periodically run <code>ocsptool</code> (see <a href="#ocsptool-Invocation">ocsptool Invocation</a>) to obtain
its certificate revocation status and serve it to the clients. That
way a client avoids an additional connection to the OCSP server.
</p>
<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005fcertificate_005fset_005focsp_005fstatus_005frequest_005ffunction">gnutls_certificate_set_ocsp_status_request_function</a> (gnutls_certificate_credentials_t <var>sc</var>, gnutls_status_request_ocsp_func <var>ocsp_func</var>, void * <var>ptr</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005focsp_005fstatus_005frequest_005ffile">gnutls_certificate_set_ocsp_status_request_file</a> (gnutls_certificate_credentials_t <var>sc</var>, const char * <var>response_file</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005fstatus_005frequest_005fenable_005fclient">gnutls_ocsp_status_request_enable_client</a> (gnutls_session_t <var>session</var>, gnutls_datum_t * <var>responder_id</var>, size_t <var>responder_id_size</var>, gnutls_datum_t * <var>extensions</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005fstatus_005frequest_005fis_005fchecked">gnutls_ocsp_status_request_is_checked</a> (gnutls_session_t <var>session</var>, unsigned int <var>flags</var>)</code></dt>
</dl>

<p>A server is required to provide the OCSP server&rsquo;s response using the <a href="#gnutls_005fcertificate_005fset_005focsp_005fstatus_005frequest_005ffile">gnutls_certificate_set_ocsp_status_request_file</a>.
The response may be obtained periodically using the following command.
</p>
<div class="example">
<pre class="example">ocsptool --ask --load-cert server_cert.pem --load-issuer the_issuer.pem
         --load-signer the_issuer.pem --outfile ocsp.response
</pre></div>

<p>Since version 3.1.3 GnuTLS clients transparently support the certificate status
request.
</p>
<hr>
<a name="SRTP"></a>
<div class="header">
<p>
Next: <a href="#Application-Layer-Protocol-Negotiation-_0028ALPN_0029" accesskey="n" rel="next">Application Layer Protocol Negotiation (ALPN)</a>, Previous: <a href="#OCSP-status-request" accesskey="p" rel="prev">OCSP status request</a>, Up: <a href="#TLS-Extensions" accesskey="u" rel="up">TLS Extensions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="SRTP-1"></a>
<h4 class="subsection">3.6.7 SRTP</h4>
<a name="index-SRTP"></a>
<a name="index-Secure-RTP"></a>

<p>The TLS protocol was extended in [<em>RFC5764</em>] to provide keying material to the
Secure RTP (SRTP) protocol. The SRTP protocol provides an encapsulation of encrypted
data that is optimized for voice data. With the SRTP TLS extension two peers can
negotiate keys using TLS or DTLS and obtain keying material for use with SRTP. The
available SRTP profiles are listed below.
</p>
<div class="float"><a name="gnutls_005fsrtp_005fprofile_005ft"></a>


<dl compact="compact">
<dt><code>GNUTLS_SRTP_AES128_CM_HMAC_SHA1_80</code></dt>
<dd><p>128 bit AES with a 80 bit HMAC-SHA1
</p></dd>
<dt><code>GNUTLS_SRTP_AES128_CM_HMAC_SHA1_32</code></dt>
<dd><p>128 bit AES with a 32 bit HMAC-SHA1
</p></dd>
<dt><code>GNUTLS_SRTP_NULL_HMAC_SHA1_80</code></dt>
<dd><p>NULL cipher with a 80 bit HMAC-SHA1
</p></dd>
<dt><code>GNUTLS_SRTP_NULL_HMAC_SHA1_32</code></dt>
<dd><p>NULL cipher with a 32 bit HMAC-SHA1
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 3.3: </strong>Supported SRTP profiles</p></div></div>
<p>To enable use the following functions.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fsrtp_005fset_005fprofile">gnutls_srtp_set_profile</a> (gnutls_session_t <var>session</var>, gnutls_srtp_profile_t <var>profile</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fsrtp_005fset_005fprofile_005fdirect">gnutls_srtp_set_profile_direct</a> (gnutls_session_t <var>session</var>, const char * <var>profiles</var>, const char ** <var>err_pos</var>)</code></dt>
</dl>

<p>To obtain the negotiated keys use the function below.
</p>




<dl>
<dt><a name="index-gnutls_005fsrtp_005fget_005fkeys"></a>Function: <em>int</em> <strong>gnutls_srtp_get_keys</strong> <em>(gnutls_session_t <var>session</var>, void * <var>key_material</var>, unsigned int <var>key_material_size</var>, gnutls_datum_t * <var>client_key</var>, gnutls_datum_t * <var>client_salt</var>, gnutls_datum_t * <var>server_key</var>, gnutls_datum_t * <var>server_salt</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>key_material</var>: Space to hold the generated key material
</p>
<p><var>key_material_size</var>: The maximum size of the key material
</p>
<p><var>client_key</var>: The master client write key, pointing inside the key material
</p>
<p><var>client_salt</var>: The master client write salt, pointing inside the key material
</p>
<p><var>server_key</var>: The master server write key, pointing inside the key material
</p>
<p><var>server_salt</var>: The master server write salt, pointing inside the key material
</p>
<p>This is a helper function to generate the keying material for SRTP.
It requires the space of the key material to be pre-allocated (should be at least
2x the maximum key size and salt size). The  <code>client_key</code> ,  <code>client_salt</code> ,  <code>server_key</code> and  <code>server_salt</code> are convenience datums that point inside the key material. They may
be <code>NULL</code> .
</p>
<p><strong>Returns:</strong> On success the size of the key material is returned,
otherwise, <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the buffer given is not 
sufficient, or a negative error code.
</p>
<p>Since 3.1.4
</p></dd></dl>

<p>Other helper functions are listed below.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fsrtp_005fget_005fselected_005fprofile">gnutls_srtp_get_selected_profile</a> (gnutls_session_t <var>session</var>, gnutls_srtp_profile_t * <var>profile</var>)</code></dt>
<dt><code><var>const char *</var> <a href="#gnutls_005fsrtp_005fget_005fprofile_005fname">gnutls_srtp_get_profile_name</a> (gnutls_srtp_profile_t <var>profile</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fsrtp_005fget_005fprofile_005fid">gnutls_srtp_get_profile_id</a> (const char * <var>name</var>, gnutls_srtp_profile_t * <var>profile</var>)</code></dt>
</dl>

<hr>
<a name="Application-Layer-Protocol-Negotiation-_0028ALPN_0029"></a>
<div class="header">
<p>
Next: <a href="#Extensions-and-Supplemental-Data" accesskey="n" rel="next">Extensions and Supplemental Data</a>, Previous: <a href="#SRTP" accesskey="p" rel="prev">SRTP</a>, Up: <a href="#TLS-Extensions" accesskey="u" rel="up">TLS Extensions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Application-Layer-Protocol-Negotiation-_0028ALPN_0029-1"></a>
<h4 class="subsection">3.6.8 Application Layer Protocol Negotiation (ALPN)</h4>
<a name="index-ALPN"></a>
<a name="index-Application-Layer-Protocol-Negotiation"></a>

<p>The TLS protocol was extended in <code>RFC7301</code> 
to provide the application layer a method of
negotiating the application protocol version. This allows for negotiation
of the application protocol during the TLS handshake, thus reducing
round-trips. The application protocol is described by an opaque
string. To enable, use the following functions.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005falpn_005fset_005fprotocols">gnutls_alpn_set_protocols</a> (gnutls_session_t <var>session</var>, const gnutls_datum_t * <var>protocols</var>, unsigned <var>protocols_size</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005falpn_005fget_005fselected_005fprotocol">gnutls_alpn_get_selected_protocol</a> (gnutls_session_t <var>session</var>, gnutls_datum_t * <var>protocol</var>)</code></dt>
</dl>

<p>Note that these functions are intended to be used with protocols that are
registered in the Application Layer Protocol Negotiation IANA registry. While
you can use them for other protocols (at the risk of collisions), it is preferable
to register them.
</p>
<hr>
<a name="Extensions-and-Supplemental-Data"></a>
<div class="header">
<p>
Previous: <a href="#Application-Layer-Protocol-Negotiation-_0028ALPN_0029" accesskey="p" rel="prev">Application Layer Protocol Negotiation (ALPN)</a>, Up: <a href="#TLS-Extensions" accesskey="u" rel="up">TLS Extensions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Extensions-and-Supplemental-Data-1"></a>
<h4 class="subsection">3.6.9 Extensions and Supplemental Data</h4>
<a name="index-Supplemental-data"></a>

<p>It is possible to transfer supplemental data during the TLS handshake, following
[<em>RFC4680</em>]. This is for &quot;custom&quot; protocol modifications for applications which
may want to transfer additional data (e.g. additional authentication messages). Such
an exchange requires a custom extension to be registered. 
The provided API for this functionality is low-level and described in <a href="#TLS-Extension-Handling">TLS Extension Handling</a>.
</p>
<hr>
<a name="How-to-use-TLS-in-application-protocols"></a>
<div class="header">
<p>
Next: <a href="#On-SSL-2-and-older-protocols" accesskey="n" rel="next">On SSL 2 and older protocols</a>, Previous: <a href="#TLS-Extensions" accesskey="p" rel="prev">TLS Extensions</a>, Up: <a href="#Introduction-to-TLS" accesskey="u" rel="up">Introduction to TLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="How-to-use-TLS-in-application-protocols-1"></a>
<h3 class="section">3.7 How to use <acronym>TLS</acronym> in application protocols</h3>

<p>This chapter is intended to provide some hints on how to use
<acronym>TLS</acronym> over simple custom made application protocols.  The
discussion below mainly refers to the <acronym>TCP/IP</acronym> transport layer
but may be extended to other ones too.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Separate-ports" accesskey="1">Separate ports</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Upward-negotiation" accesskey="2">Upward negotiation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Separate-ports"></a>
<div class="header">
<p>
Next: <a href="#Upward-negotiation" accesskey="n" rel="next">Upward negotiation</a>, Up: <a href="#How-to-use-TLS-in-application-protocols" accesskey="u" rel="up">How to use TLS in application protocols</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Separate-ports-1"></a>
<h4 class="subsection">3.7.1 Separate ports</h4>

<p>Traditionally <acronym>SSL</acronym> was used in application protocols by
assigning a new port number for the secure services. By doing this two
separate ports were assigned, one for the non-secure sessions, and one
for the secure sessions. This method ensures that if a user requests a
secure session then the client will attempt to connect to the secure port
and fail otherwise. The only possible attack with this method is to perform
a denial of service attack. The most famous example of this method is
&ldquo;HTTP over TLS&rdquo; or <acronym>HTTPS</acronym> protocol [<em>RFC2818</em>].
</p>
<p>Despite its wide use, this method has several issues. This
approach starts the <acronym>TLS</acronym> Handshake procedure just after the
client connects on the &mdash;so called&mdash; secure port.  That way the
<acronym>TLS</acronym> protocol does not know anything about the client, and
popular methods like the host advertising in HTTP do not
work<a name="DOCF6" href="#FOOT6"><sup>6</sup></a>.  There is no way for the client to say &ldquo;I
connected to YYY server&rdquo; before the Handshake starts, so the server
cannot possibly know which certificate to use.
</p>
<p>Other than that it requires two separate ports to run a single
service, which is unnecessary complication. Due to the fact that there
is a limitation on the available privileged ports, this approach was
soon deprecated in favor of upward negotiation.
</p>
<hr>
<a name="Upward-negotiation"></a>
<div class="header">
<p>
Previous: <a href="#Separate-ports" accesskey="p" rel="prev">Separate ports</a>, Up: <a href="#How-to-use-TLS-in-application-protocols" accesskey="u" rel="up">How to use TLS in application protocols</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Upward-negotiation-1"></a>
<h4 class="subsection">3.7.2 Upward negotiation</h4>

<p>Other application protocols<a name="DOCF7" href="#FOOT7"><sup>7</sup></a>  use a
different approach to enable the secure layer.  They use something
often called as the &ldquo;TLS upgrade&rdquo; method. This method is quite tricky but it
is more flexible. The idea is to extend the application protocol to
have a &ldquo;STARTTLS&rdquo; request, whose purpose it to start the TLS
protocols just after the client requests it.  This approach
does not require any extra port to be reserved.
There is even an extension to HTTP protocol to support 
this method [<em>RFC2817</em>].
</p>
<p>The tricky part, in this method, is that the &ldquo;STARTTLS&rdquo; request is
sent in the clear, thus is vulnerable to modifications.  A typical
attack is to modify the messages in a way that the client is fooled
and thinks that the server does not have the &ldquo;STARTTLS&rdquo; capability.
See a typical conversation of a hypothetical protocol:
</p>
<blockquote>
<p>(client connects to the server)
</p>
<p>CLIENT: HELLO I&rsquo;M MR. XXX
</p>
<p>SERVER: NICE TO MEET YOU XXX
</p>
<p>CLIENT: PLEASE START TLS
</p>
<p>SERVER: OK
</p>
<p>*** TLS STARTS
</p>
<p>CLIENT: HERE ARE SOME CONFIDENTIAL DATA
</p></blockquote>

<p>And an example of a conversation where someone is acting
in between:
</p>
<blockquote>
<p>(client connects to the server)
</p>
<p>CLIENT: HELLO I&rsquo;M MR. XXX
</p>
<p>SERVER: NICE TO MEET YOU XXX
</p>
<p>CLIENT: PLEASE START TLS
</p>
<p>(here someone inserts this message)
</p>
<p>SERVER: SORRY I DON&rsquo;T HAVE THIS CAPABILITY
</p>
<p>CLIENT: HERE ARE SOME CONFIDENTIAL DATA
</p></blockquote>

<p>As you can see above the client was fooled, and was na&iuml;ve enough to
send the confidential data in the clear, despite the server telling the
client that it does not support &ldquo;STARTTLS&rdquo;.
</p>
<p>How do we avoid the above attack? As you may have already noticed this
situation is easy to avoid.  The client has to ask the user before it
connects whether the user requests <acronym>TLS</acronym> or not.  If the user
answered that he certainly wants the secure layer the last
conversation should be:
</p>
<blockquote>
<p>(client connects to the server)
</p>
<p>CLIENT: HELLO I&rsquo;M MR. XXX
</p>
<p>SERVER: NICE TO MEET YOU XXX
</p>
<p>CLIENT: PLEASE START TLS
</p>
<p>(here someone inserts this message)
</p>
<p>SERVER: SORRY I DON&rsquo;T HAVE THIS CAPABILITY
</p>
<p>CLIENT: BYE
</p>
<p>(the client notifies the user that the secure connection was not possible)
</p></blockquote>

<p>This method, if implemented properly, is far better than the
traditional method, and the security properties remain the same, since
only denial of service is possible. The benefit is that the server may
request additional data before the <acronym>TLS</acronym> Handshake protocol
starts, in order to send the correct certificate, use the correct
password file, or anything else!
</p>
<hr>
<a name="On-SSL-2-and-older-protocols"></a>
<div class="header">
<p>
Previous: <a href="#How-to-use-TLS-in-application-protocols" accesskey="p" rel="prev">How to use TLS in application protocols</a>, Up: <a href="#Introduction-to-TLS" accesskey="u" rel="up">Introduction to TLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="On-SSL-2-and-older-protocols-1"></a>
<h3 class="section">3.8 On SSL 2 and older protocols</h3>
<a name="index-SSL-2"></a>

<p>One of the initial decisions in the <acronym>GnuTLS</acronym> development was
to implement the known security protocols for the transport layer.
Initially <acronym>TLS</acronym> 1.0 was implemented since it was the latest at
that time, and was considered to be the most advanced in security
properties.  Later the <acronym>SSL</acronym> 3.0 protocol was implemented
since it is still the only protocol supported by several servers and
there are no serious security vulnerabilities known.
</p>
<p>One question that may arise is why we didn&rsquo;t implement <acronym>SSL</acronym>
2.0 in the library.  There are several reasons, most important being
that it has serious security flaws, unacceptable for a modern security
library.  Other than that, this protocol is barely used by anyone
these days since it has been deprecated since 1996.  The security
problems in <acronym>SSL</acronym> 2.0 include:
</p>
<ul>
<li> Message integrity compromised.
The <acronym>SSLv2</acronym> message authentication uses the MD5 function, and
is insecure.

</li><li> Man-in-the-middle attack.
There is no protection of the handshake in <acronym>SSLv2</acronym>, which
permits a man-in-the-middle attack.

</li><li> Truncation attack.
<acronym>SSLv2</acronym> relies on TCP FIN to close the session, so the
attacker can forge a TCP FIN, and the peer cannot tell if it was a
legitimate end of data or not.

</li><li> Weak message integrity for export ciphers.
The cryptographic keys in <acronym>SSLv2</acronym> are used for both message
authentication and encryption, so if weak encryption schemes are
negotiated (say 40-bit keys) the message authentication code uses the
same weak key, which isn&rsquo;t necessary.

</li></ul>

<a name="index-PCT"></a>
<p>Other protocols such as Microsoft&rsquo;s <acronym>PCT</acronym> 1 and <acronym>PCT</acronym>
2 were not implemented because they were also abandoned and deprecated
by <acronym>SSL</acronym> 3.0 and later <acronym>TLS</acronym> 1.0.
</p>


<hr>
<a name="Authentication-methods"></a>
<div class="header">
<p>
Next: <a href="#Hardware-security-modules-and-abstract-key-types" accesskey="n" rel="next">Hardware security modules and abstract key types</a>, Previous: <a href="#Introduction-to-TLS" accesskey="p" rel="prev">Introduction to TLS</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Authentication-methods-1"></a>
<h2 class="chapter">4 Authentication methods</h2>
<a name="index-authentication-methods"></a>

<p>The initial key exchange of the TLS protocol performs authentication
of the peers. In typical scenarios the server is authenticated to
the client, and optionally the client to the server.
</p>
<p>While many associate TLS with X.509 certificates and public key
authentication, the protocol supports various authentication methods,
including pre-shared keys, and passwords. In this chapter a description
of the existing authentication methods is provided, as well as some
guidance on which use-cases each method can be used at.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Certificate-authentication" accesskey="1">Certificate authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#More-on-certificate-authentication" accesskey="2">More on certificate authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Shared_002dkey-and-anonymous-authentication" accesskey="3">Shared-key and anonymous authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Selecting-an-appropriate-authentication-method" accesskey="4">Selecting an appropriate authentication method</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Certificate-authentication"></a>
<div class="header">
<p>
Next: <a href="#More-on-certificate-authentication" accesskey="n" rel="next">More on certificate authentication</a>, Up: <a href="#Authentication-methods" accesskey="u" rel="up">Authentication methods</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Certificate-authentication-1"></a>
<h3 class="section">4.1 Certificate authentication</h3>
<a name="index-certificate-authentication"></a>

<p>The most known authentication method of <acronym>TLS</acronym> are certificates.
The PKIX [<em>PKIX</em>] public key infrastructure is daily used by anyone
using a browser today. <acronym>GnuTLS</acronym> supports both 
<acronym>X.509</acronym> certificates [<em>PKIX</em>] and <acronym>OpenPGP</acronym>
certificates using a common API.
</p>
<p>The key exchange algorithms supported by certificate authentication are
shown in <a href="#tab_003akey_002dexchange">Table 4.1</a>.
</p>
<div class="float"><a name="tab_003akey_002dexchange"></a>
<table>
<thead><tr><th width="20%">Key exchange</th><th width="70%">Description</th></tr></thead>
<tr><td width="20%">RSA</td><td width="70%">The RSA algorithm is used to encrypt a key and send it to the peer.
The certificate must allow the key to be used for encryption.</td></tr>
<tr><td width="20%">DHE_RSA</td><td width="70%">The RSA algorithm is used to sign ephemeral Diffie-Hellman parameters
which are sent to the peer. The key in the certificate must allow the
key to be used for signing. Note that key exchange algorithms which
use ephemeral Diffie-Hellman parameters, offer perfect forward
secrecy. That means that even if the private key used for signing is
compromised, it cannot be used to reveal past session data.</td></tr>
<tr><td width="20%">ECDHE_RSA</td><td width="70%">The RSA algorithm is used to sign ephemeral elliptic curve Diffie-Hellman 
parameters which are sent to the peer. The key in the certificate must allow 
the key to be used for signing. It also offers perfect forward
secrecy. That means that even if the private key used for signing is
compromised, it cannot be used to reveal past session data.</td></tr>
<tr><td width="20%">DHE_DSS</td><td width="70%">The DSA algorithm is used to sign ephemeral Diffie-Hellman parameters
which are sent to the peer. The certificate must contain DSA
parameters to use this key exchange algorithm. DSA is the algorithm
of the Digital Signature Standard (DSS).</td></tr>
<tr><td width="20%">ECDHE_ECDSA</td><td width="70%">The Elliptic curve DSA algorithm is used to sign ephemeral elliptic
curve Diffie-Hellman parameters which are sent to the peer. The 
certificate must contain ECDSA parameters (i.e., EC and marked for signing) 
to use this key exchange algorithm.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 4.1: </strong>Supported key exchange algorithms.</p></div></div>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#X_002e509-certificates" accesskey="1">X.509 certificates</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OpenPGP-certificates" accesskey="2">OpenPGP certificates</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Advanced-certificate-verification" accesskey="3">Advanced certificate verification</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Digital-signatures" accesskey="4">Digital signatures</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="X_002e509-certificates"></a>
<div class="header">
<p>
Next: <a href="#OpenPGP-certificates" accesskey="n" rel="next">OpenPGP certificates</a>, Up: <a href="#Certificate-authentication" accesskey="u" rel="up">Certificate authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="X_002e509-certificates-1"></a>
<h4 class="subsection">4.1.1 <acronym>X.509</acronym> certificates</h4>
<a name="index-X_002e509-certificates"></a>

<p>The <acronym>X.509</acronym> protocols rely on a hierarchical trust model. In
this trust model Certification Authorities (CAs) are used to certify
entities.  Usually more than one certification authorities exist, and
certification authorities may certify other authorities to issue
certificates as well, following a hierarchical model.
</p>
<div class="float"><a name="fig_002dx509"></a>
<img src="gnutls-x509.png" alt="gnutls-x509">

<div class="float-caption"><p><strong>Figure 4.1: </strong>An example of the X.509 hierarchical trust model.</p></div></div>
<p>One needs to trust one or more CAs for his secure communications. In
that case only the certificates issued by the trusted authorities are
acceptable.  The framework is illustrated on <a href="#fig_002dx509">Figure 4.1</a>.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#X_002e509-certificate-structure" accesskey="1">X.509 certificate structure</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Importing-an-X_002e509-certificate" accesskey="2">Importing an X.509 certificate</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#X_002e509-certificate-names" accesskey="3">X.509 certificate names</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#X_002e509-distinguished-names" accesskey="4">X.509 distinguished names</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#X_002e509-extensions" accesskey="5">X.509 extensions</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#X_002e509-public-and-private-keys" accesskey="6">X.509 public and private keys</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Verifying-X_002e509-certificate-paths" accesskey="7">Verifying X.509 certificate paths</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Verifying-a-certificate-in-the-context-of-TLS-session" accesskey="8">Verifying a certificate in the context of TLS session</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Verification-using-PKCS11" accesskey="9">Verification using PKCS11</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="X_002e509-certificate-structure"></a>
<div class="header">
<p>
Next: <a href="#Importing-an-X_002e509-certificate" accesskey="n" rel="next">Importing an X.509 certificate</a>, Up: <a href="#X_002e509-certificates" accesskey="u" rel="up">X.509 certificates</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="X_002e509-certificate-structure-1"></a>
<h4 class="subsubsection">4.1.1.1 <acronym>X.509</acronym> certificate structure</h4>

<p>An <acronym>X.509</acronym> certificate usually contains information about the
certificate holder, the signer, a unique serial number, expiration
dates and some other fields [<em>PKIX</em>] as shown in <a href="#tab_003ax509">Table 4.2</a>.
</p>
<div class="float"><a name="tab_003ax509"></a>
<table>
<thead><tr><th width="20%">Field</th><th width="70%">Description</th></tr></thead>
<tr><td width="20%">version</td><td width="70%">The field that indicates the version of the certificate.</td></tr>
<tr><td width="20%">serialNumber</td><td width="70%">This field holds a unique serial number per certificate.</td></tr>
<tr><td width="20%">signature</td><td width="70%">The issuing authority&rsquo;s signature.</td></tr>
<tr><td width="20%">issuer</td><td width="70%">Holds the issuer&rsquo;s distinguished name.</td></tr>
<tr><td width="20%">validity</td><td width="70%">The activation and expiration dates.</td></tr>
<tr><td width="20%">subject</td><td width="70%">The subject&rsquo;s distinguished name of the certificate.</td></tr>
<tr><td width="20%">extensions</td><td width="70%">The extensions are fields only present in version 3 certificates.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 4.2: </strong>X.509 certificate fields.</p></div></div>
<p>The certificate&rsquo;s <em>subject or issuer name</em> is not just a single
string.  It is a Distinguished name and in the <acronym>ASN.1</acronym>
notation is a sequence of several object identifiers with their corresponding
values. Some of available OIDs to be used in an <acronym>X.509</acronym>
distinguished name are defined in <samp>gnutls/x509.h</samp>.
</p>
<p>The <em>Version</em> field in a certificate has values either 1 or 3 for
version 3 certificates.  Version 1 certificates do not support the
extensions field so it is not possible to distinguish a CA from a
person, thus their usage should be avoided.
</p>
<p>The <em>validity</em> dates are there to indicate the date that the
specific certificate was activated and the date the certificate&rsquo;s key
would be considered invalid.
</p>

<p>In <acronym>GnuTLS</acronym> the <acronym>X.509</acronym> certificate structures are
handled using the <code>gnutls_x509_crt_t</code> type and the corresponding
private keys with the <code>gnutls_x509_privkey_t</code> type.  All the
available functions for <acronym>X.509</acronym> certificate handling have
their prototypes in <samp>gnutls/x509.h</samp>. An example program to
demonstrate the <acronym>X.509</acronym> parsing capabilities can be found in
<a href="#ex_002dx509_002dinfo">ex-x509-info</a>.
</p>
<hr>
<a name="Importing-an-X_002e509-certificate"></a>
<div class="header">
<p>
Next: <a href="#X_002e509-certificate-names" accesskey="n" rel="next">X.509 certificate names</a>, Previous: <a href="#X_002e509-certificate-structure" accesskey="p" rel="prev">X.509 certificate structure</a>, Up: <a href="#X_002e509-certificates" accesskey="u" rel="up">X.509 certificates</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Importing-an-X_002e509-certificate-1"></a>
<h4 class="subsubsection">4.1.1.2 Importing an X.509 certificate</h4>

<p>The certificate structure should be initialized using <a href="#gnutls_005fx509_005fcrt_005finit">gnutls_x509_crt_init</a>, and 
a certificate structure can be imported using <a href="#gnutls_005fx509_005fcrt_005fimport">gnutls_x509_crt_import</a>. 
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005finit">gnutls_x509_crt_init</a> (gnutls_x509_crt_t * <var>cert</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fimport">gnutls_x509_crt_import</a> (gnutls_x509_crt_t <var>cert</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fx509_005fcrt_005fdeinit">gnutls_x509_crt_deinit</a> (gnutls_x509_crt_t <var>cert</var>)</code></dt>
</dl>

<p>In several functions an array of certificates is required. To assist in initialization
and import the following two functions are provided.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005flist_005fimport">gnutls_x509_crt_list_import</a> (gnutls_x509_crt_t * <var>certs</var>, unsigned int * <var>cert_max</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005flist_005fimport2">gnutls_x509_crt_list_import2</a> (gnutls_x509_crt_t ** <var>certs</var>, unsigned int * <var>size</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int <var>flags</var>)</code></dt>
</dl>

<p>In all cases after use a certificate must be deinitialized using <a href="#gnutls_005fx509_005fcrt_005fdeinit">gnutls_x509_crt_deinit</a>.
Note that although the functions above apply to <code>gnutls_x509_crt_t</code> structure, similar functions
exist for the CRL structure <code>gnutls_x509_crl_t</code>.
</p>
<hr>
<a name="X_002e509-certificate-names"></a>
<div class="header">
<p>
Next: <a href="#X_002e509-distinguished-names" accesskey="n" rel="next">X.509 distinguished names</a>, Previous: <a href="#Importing-an-X_002e509-certificate" accesskey="p" rel="prev">Importing an X.509 certificate</a>, Up: <a href="#X_002e509-certificates" accesskey="u" rel="up">X.509 certificates</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="X_002e509-certificate-names-1"></a>
<h4 class="subsubsection">4.1.1.3 X.509 certificate names</h4>
<a name="index-X_002e509-certificate-name"></a>

<p>X.509 certificates allow for multiple names and types of names to be specified.
CA certificates often rely on X.509 distinguished names (see <a href="#X_002e509-distinguished-names">X.509 distinguished names</a>)
for unique identification, while end-user and server certificates rely on the
&rsquo;subject alternative names&rsquo;. The subject alternative names provide a typed name, e.g.,
a DNS name, or an email address, which identifies the owner of the certificate.
The following functions provide access to that names.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fname2">gnutls_x509_crt_get_subject_alt_name2</a> (gnutls_x509_crt_t <var>cert</var>, unsigned int <var>seq</var>, void * <var>san</var>, size_t * <var>san_size</var>, unsigned int * <var>san_type</var>, unsigned int * <var>critical</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fset_005fsubject_005falt_005fname">gnutls_x509_crt_set_subject_alt_name</a> (gnutls_x509_crt_t <var>crt</var>, gnutls_x509_subject_alt_name_t <var>type</var>, const void * <var>data</var>, unsigned int <var>data_size</var>, unsigned int <var>flags</var>)</code></dt>
</dl>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fsubject_005falt_005fnames_005finit">gnutls_subject_alt_names_init</a> (gnutls_subject_alt_names_t * <var>sans</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fsubject_005falt_005fnames_005fget">gnutls_subject_alt_names_get</a> (gnutls_subject_alt_names_t <var>sans</var>, unsigned int <var>seq</var>, unsigned int * <var>san_type</var>, gnutls_datum_t * <var>san</var>, gnutls_datum_t * <var>othername_oid</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fsubject_005falt_005fnames_005fset">gnutls_subject_alt_names_set</a> (gnutls_subject_alt_names_t <var>sans</var>, unsigned int <var>san_type</var>, const gnutls_datum_t * <var>san</var>, const char * <var>othername_oid</var>)</code></dt>
</dl>

<p>Note however, that server certificates often used the Common Name (CN), part of the
certificate DistinguishedName to place a single DNS address. That practice is discouraged
(see [<em>RFC6125</em>]), because only a single address can be specified, and the CN field is
free-form making matching ambiguous.
</p>
<hr>
<a name="X_002e509-distinguished-names"></a>
<div class="header">
<p>
Next: <a href="#X_002e509-extensions" accesskey="n" rel="next">X.509 extensions</a>, Previous: <a href="#X_002e509-certificate-names" accesskey="p" rel="prev">X.509 certificate names</a>, Up: <a href="#X_002e509-certificates" accesskey="u" rel="up">X.509 certificates</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="X_002e509-distinguished-names-1"></a>
<h4 class="subsubsection">4.1.1.4 X.509 distinguished names</h4>
<a name="index-X_002e509-distinguished-name"></a>

<p>The &ldquo;subject&rdquo; of an X.509 certificate is not described by
a single name, but rather with a distinguished name. This in
X.509 terminology is a list of strings each associated an object
identifier. To make things simple GnuTLS provides <a href="#gnutls_005fx509_005fcrt_005fget_005fdn2">gnutls_x509_crt_get_dn2</a>
which follows the rules in [<em>RFC4514</em>] and returns a single
string. Access to each string by individual object identifiers
can be accessed using <a href="#gnutls_005fx509_005fcrt_005fget_005fdn_005fby_005foid">gnutls_x509_crt_get_dn_by_oid</a>.
</p>




<dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fdn2"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_dn2</strong> <em>(gnutls_x509_crt_t <var>cert</var>, gnutls_datum_t * <var>dn</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>dn</var>: a pointer to a structure to hold the name
</p>
<p>This function will allocate buffer and copy the name of the Certificate.
The name will be in the form &quot;C=xxxx,O=yyyy,CN=zzzz&quot; as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.10
</p></dd></dl>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fdn">gnutls_x509_crt_get_dn</a> (gnutls_x509_crt_t <var>cert</var>, char * <var>buf</var>, size_t * <var>buf_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fdn_005fby_005foid">gnutls_x509_crt_get_dn_by_oid</a> (gnutls_x509_crt_t <var>cert</var>, const char * <var>oid</var>, int <var>indx</var>, unsigned int <var>raw_flag</var>, void * <var>buf</var>, size_t * <var>buf_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fdn_005foid">gnutls_x509_crt_get_dn_oid</a> (gnutls_x509_crt_t <var>cert</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>oid_size</var>)</code></dt>
</dl>

<p>Similar functions exist to access the distinguished name
of the issuer of the certificate.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn">gnutls_x509_crt_get_issuer_dn</a> (gnutls_x509_crt_t <var>cert</var>, char * <var>buf</var>, size_t * <var>buf_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn2">gnutls_x509_crt_get_issuer_dn2</a> (gnutls_x509_crt_t <var>cert</var>, gnutls_datum_t * <var>dn</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn_005fby_005foid">gnutls_x509_crt_get_issuer_dn_by_oid</a> (gnutls_x509_crt_t <var>cert</var>, const char * <var>oid</var>, int <var>indx</var>, unsigned int <var>raw_flag</var>, void * <var>buf</var>, size_t * <var>buf_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn_005foid">gnutls_x509_crt_get_issuer_dn_oid</a> (gnutls_x509_crt_t <var>cert</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>oid_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fissuer">gnutls_x509_crt_get_issuer</a> (gnutls_x509_crt_t <var>cert</var>, gnutls_x509_dn_t * <var>dn</var>)</code></dt>
</dl>

<p>The more powerful <a href="#gnutls_005fx509_005fcrt_005fget_005fsubject">gnutls_x509_crt_get_subject</a> and 
<a href="#gnutls_005fx509_005fdn_005fget_005frdn_005fava">gnutls_x509_dn_get_rdn_ava</a> provide efficient but low-level access
to the contents of the distinguished name structure.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fsubject">gnutls_x509_crt_get_subject</a> (gnutls_x509_crt_t <var>cert</var>, gnutls_x509_dn_t * <var>dn</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fissuer">gnutls_x509_crt_get_issuer</a> (gnutls_x509_crt_t <var>cert</var>, gnutls_x509_dn_t * <var>dn</var>)</code></dt>
</dl>




<dl>
<dt><a name="index-gnutls_005fx509_005fdn_005fget_005frdn_005fava"></a>Function: <em>int</em> <strong>gnutls_x509_dn_get_rdn_ava</strong> <em>(gnutls_x509_dn_t <var>dn</var>, int <var>irdn</var>, int <var>iava</var>, gnutls_x509_ava_st * <var>ava</var>)</em></dt>
<dd><p><var>dn</var>: a pointer to DN
</p>
<p><var>irdn</var>: index of RDN
</p>
<p><var>iava</var>: index of AVA.
</p>
<p><var>ava</var>: Pointer to structure which will hold output information.
</p>
<p>Get pointers to data within the DN. The format of the  <code>ava</code> structure
is shown below.
</p>
<p>struct gnutls_x509_ava_st {
gnutls_datum_t oid;
gnutls_datum_t value;
unsigned long value_tag;
};
</p>
<p>The X.509 distinguished name is a sequence of sequences of strings
and this is what the  <code>irdn</code> and  <code>iava</code> indexes model.
</p>
<p>Note that  <code>ava</code> will contain pointers into the  <code>dn</code> structure which
in turns points to the original certificate. Thus you should not
modify any data or deallocate any of those.
</p>
<p>This is a low-level function that requires the caller to do the
value conversions when necessary (e.g. from UCS-2).
</p>
<p><strong>Returns:</strong> Returns 0 on success, or an error code.
</p></dd></dl>

<hr>
<a name="X_002e509-extensions"></a>
<div class="header">
<p>
Next: <a href="#X_002e509-public-and-private-keys" accesskey="n" rel="next">X.509 public and private keys</a>, Previous: <a href="#X_002e509-distinguished-names" accesskey="p" rel="prev">X.509 distinguished names</a>, Up: <a href="#X_002e509-certificates" accesskey="u" rel="up">X.509 certificates</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="X_002e509-extensions-1"></a>
<h4 class="subsubsection">4.1.1.5 X.509 extensions</h4>
<a name="index-X_002e509-extensions"></a>

<p>X.509 version 3 certificates include a list of extensions that can
be used to obtain additional information on the subject or the issuer
of the certificate. Those may be e-mail addresses, flags that indicate whether the
belongs to a CA etc.  All the supported <acronym>X.509</acronym> version 3
extensions are shown in <a href="#tab_003ax509_002dext">Table 4.3</a>.
</p>
<p>The certificate extensions access is split into two parts. The first
requires to retrieve the extension, and the second is the parsing part.
</p>
<p>To enumerate and retrieve the DER-encoded extension data available in a certificate the following
two functions are available.
</p><dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fextension_005finfo">gnutls_x509_crt_get_extension_info</a> (gnutls_x509_crt_t <var>cert</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>oid_size</var>, unsigned int * <var>critical</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fextension_005fdata2">gnutls_x509_crt_get_extension_data2</a> (gnutls_x509_crt_t <var>cert</var>, unsigned <var>indx</var>, gnutls_datum_t * <var>data</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fextension_005fby_005foid2">gnutls_x509_crt_get_extension_by_oid2</a> (gnutls_x509_crt_t <var>cert</var>, const char * <var>oid</var>, int <var>indx</var>, gnutls_datum_t * <var>output</var>, unsigned int * <var>critical</var>)</code></dt>
</dl>

<p>After a supported DER-encoded extension is retrieved it can be parsed using the APIs in <code>x509-ext.h</code>.
Complex extensions may require initializing an intermediate structure that holds the
parsed extension data. Examples of simple parsing functions are shown below.
</p><dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fext_005fimport_005fbasic_005fconstraints">gnutls_x509_ext_import_basic_constraints</a> (const gnutls_datum_t * <var>ext</var>, unsigned int * <var>ca</var>, int * <var>pathlen</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fext_005fexport_005fbasic_005fconstraints">gnutls_x509_ext_export_basic_constraints</a> (unsigned int <var>ca</var>, int <var>pathlen</var>, gnutls_datum_t * <var>ext</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fext_005fimport_005fkey_005fusage">gnutls_x509_ext_import_key_usage</a> (const gnutls_datum_t * <var>ext</var>, unsigned int * <var>key_usage</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fext_005fexport_005fkey_005fusage">gnutls_x509_ext_export_key_usage</a> (unsigned int <var>usage</var>, gnutls_datum_t * <var>ext</var>)</code></dt>
</dl>

<p>More complex extensions, such as Name Constraints, require an intermediate structure, in that
case <code>gnutls_x509_name_constraints_t</code> to be initialized in order to store the parsed
extension data. 
</p><dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fext_005fimport_005fname_005fconstraints">gnutls_x509_ext_import_name_constraints</a> (const gnutls_datum_t * <var>ext</var>, gnutls_x509_name_constraints_t <var>nc</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fext_005fexport_005fname_005fconstraints">gnutls_x509_ext_export_name_constraints</a> (gnutls_x509_name_constraints_t <var>nc</var>, gnutls_datum_t * <var>ext</var>)</code></dt>
</dl>

<p>After the name constraints are extracted in the structure, the following functions
can be used to access them.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fname_005fconstraints_005fget_005fpermitted">gnutls_x509_name_constraints_get_permitted</a> (gnutls_x509_name_constraints_t <var>nc</var>, unsigned <var>idx</var>, unsigned * <var>type</var>, gnutls_datum_t * <var>name</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fname_005fconstraints_005fget_005fexcluded">gnutls_x509_name_constraints_get_excluded</a> (gnutls_x509_name_constraints_t <var>nc</var>, unsigned <var>idx</var>, unsigned * <var>type</var>, gnutls_datum_t * <var>name</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fname_005fconstraints_005fadd_005fpermitted">gnutls_x509_name_constraints_add_permitted</a> (gnutls_x509_name_constraints_t <var>nc</var>, gnutls_x509_subject_alt_name_t <var>type</var>, const gnutls_datum_t * <var>name</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fname_005fconstraints_005fadd_005fexcluded">gnutls_x509_name_constraints_add_excluded</a> (gnutls_x509_name_constraints_t <var>nc</var>, gnutls_x509_subject_alt_name_t <var>type</var>, const gnutls_datum_t * <var>name</var>)</code></dt>
</dl>
<dl compact="compact">
<dt><code><var>unsigned</var> <a href="#gnutls_005fx509_005fname_005fconstraints_005fcheck">gnutls_x509_name_constraints_check</a> (gnutls_x509_name_constraints_t <var>nc</var>, gnutls_x509_subject_alt_name_t <var>type</var>, const gnutls_datum_t * <var>name</var>)</code></dt>
<dt><code><var>unsigned</var> <a href="#gnutls_005fx509_005fname_005fconstraints_005fcheck_005fcrt">gnutls_x509_name_constraints_check_crt</a> (gnutls_x509_name_constraints_t <var>nc</var>, gnutls_x509_subject_alt_name_t <var>type</var>, gnutls_x509_crt_t <var>cert</var>)</code></dt>
</dl>

<p>Other utility functions are listed below.
</p><dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fname_005fconstraints_005finit">gnutls_x509_name_constraints_init</a> (gnutls_x509_name_constraints_t * <var>nc</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fx509_005fname_005fconstraints_005fdeinit">gnutls_x509_name_constraints_deinit</a> (gnutls_x509_name_constraints_t <var>nc</var>)</code></dt>
</dl>

<p>Similar functions exist for all of the other supported extensions, listed in <a href="#tab_003ax509_002dext">Table 4.3</a>.
</p>
<div class="float"><a name="tab_003ax509_002dext"></a>
<table>
<thead><tr><th width="30%">Extension</th><th width="20%">OID</th><th width="40%">Description</th></tr></thead>
<tr><td width="30%">Subject key id</td><td width="20%">2.5.29.14</td><td width="40%">An identifier of the key of the subject.</td></tr>
<tr><td width="30%">Key usage</td><td width="20%">2.5.29.15</td><td width="40%">Constraints the key&rsquo;s usage of the certificate.</td></tr>
<tr><td width="30%">Private key usage period</td><td width="20%">2.5.29.16</td><td width="40%">Constraints the validity time of the private key.</td></tr>
<tr><td width="30%">Subject alternative name</td><td width="20%">2.5.29.17</td><td width="40%">Alternative names to subject&rsquo;s distinguished name.</td></tr>
<tr><td width="30%">Issuer alternative name</td><td width="20%">2.5.29.18</td><td width="40%">Alternative names to the issuer&rsquo;s distinguished name.</td></tr>
<tr><td width="30%">Basic constraints</td><td width="20%">2.5.29.19</td><td width="40%">Indicates whether this is a CA certificate or not, and specify the
maximum path lengths of certificate chains.</td></tr>
<tr><td width="30%">Name constraints</td><td width="20%">2.5.29.30</td><td width="40%">A field in CA certificates that restricts the scope of the name of
issued certificates.</td></tr>
<tr><td width="30%">CRL distribution points</td><td width="20%">2.5.29.31</td><td width="40%">This extension is set by the CA, in order to inform about the issued
CRLs.</td></tr>
<tr><td width="30%">Certificate policy</td><td width="20%">2.5.29.32</td><td width="40%">This extension is set to indicate the certificate policy as object
identifier and may contain a descriptive string or URL.</td></tr>
<tr><td width="30%">Authority key identifier</td><td width="20%">2.5.29.35</td><td width="40%">An identifier of the key of the issuer of the certificate. That is
used to distinguish between different keys of the same issuer.</td></tr>
<tr><td width="30%">Extended key usage</td><td width="20%">2.5.29.37</td><td width="40%">Constraints the purpose of the certificate.</td></tr>
<tr><td width="30%">Authority information access</td><td width="20%">1.3.6.1.5.5.7.1.1</td><td width="40%">Information on services by the issuer of the certificate.</td></tr>
<tr><td width="30%">Proxy Certification Information</td><td width="20%">1.3.6.1.5.5.7.1.14</td><td width="40%">Proxy Certificates includes this extension that contains the OID of
the proxy policy language used, and can specify limits on the maximum
lengths of proxy chains.  Proxy Certificates are specified in
[<em>RFC3820</em>].</td></tr>
</table>

<div class="float-caption"><p><strong>Table 4.3: </strong>Supported X.509 certificate extensions.</p></div></div>
<p>Note, that there are also direct APIs to access extensions that may
be simpler to use for non-complex extensions. They are available
in <code>x509.h</code> and some examples are listed below.
</p><dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fbasic_005fconstraints">gnutls_x509_crt_get_basic_constraints</a> (gnutls_x509_crt_t <var>cert</var>, unsigned int * <var>critical</var>, unsigned int * <var>ca</var>, int * <var>pathlen</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fset_005fbasic_005fconstraints">gnutls_x509_crt_set_basic_constraints</a> (gnutls_x509_crt_t <var>crt</var>, unsigned int <var>ca</var>, int <var>pathLenConstraint</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fkey_005fusage">gnutls_x509_crt_get_key_usage</a> (gnutls_x509_crt_t <var>cert</var>, unsigned int * <var>key_usage</var>, unsigned int * <var>critical</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fset_005fkey_005fusage">gnutls_x509_crt_set_key_usage</a> (gnutls_x509_crt_t <var>crt</var>, unsigned int <var>usage</var>)</code></dt>
</dl>


<hr>
<a name="X_002e509-public-and-private-keys"></a>
<div class="header">
<p>
Next: <a href="#Verifying-X_002e509-certificate-paths" accesskey="n" rel="next">Verifying X.509 certificate paths</a>, Previous: <a href="#X_002e509-extensions" accesskey="p" rel="prev">X.509 extensions</a>, Up: <a href="#X_002e509-certificates" accesskey="u" rel="up">X.509 certificates</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Accessing-public-and-private-keys"></a>
<h4 class="subsubsection">4.1.1.6 Accessing public and private keys</h4>

<p>Each X.509 certificate contains a public key that corresponds to a private key. To
get a unique identifier of the public key the <a href="#gnutls_005fx509_005fcrt_005fget_005fkey_005fid">gnutls_x509_crt_get_key_id</a>
function is provided. To export the public key or its parameters you may need
to convert the X.509 structure to a <code>gnutls_pubkey_t</code>. See 
<a href="#Abstract-public-keys">Abstract public keys</a> for more information.
</p>




<dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_key_id</strong> <em>(gnutls_x509_crt_t <var>crt</var>, unsigned int <var>flags</var>, unsigned char * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>flags</var>: should be one of the flags from <code>gnutls_keyid_flags_t</code> 
</p>
<p><var>output_data</var>: will contain the key ID
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will return a unique ID that depends on the public
key parameters. This ID can be used in checking whether a
certificate corresponds to the given private key.
</p>
<p>If the buffer provided is not long enough to hold the output, then
*output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
be returned.  The output will normally be a SHA-1 hash output,
which is 20 bytes.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p></dd></dl>

<p>The private key parameters may be directly accessed by using one of the following functions.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fprivkey_005fget_005fpk_005falgorithm2">gnutls_x509_privkey_get_pk_algorithm2</a> (gnutls_x509_privkey_t <var>key</var>, unsigned int * <var>bits</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fprivkey_005fexport_005frsa_005fraw2">gnutls_x509_privkey_export_rsa_raw2</a> (gnutls_x509_privkey_t <var>key</var>, gnutls_datum_t * <var>m</var>, gnutls_datum_t * <var>e</var>, gnutls_datum_t * <var>d</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>u</var>, gnutls_datum_t * <var>e1</var>, gnutls_datum_t * <var>e2</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fprivkey_005fexport_005fecc_005fraw">gnutls_x509_privkey_export_ecc_raw</a> (gnutls_x509_privkey_t <var>key</var>, gnutls_ecc_curve_t * <var>curve</var>, gnutls_datum_t * <var>x</var>, gnutls_datum_t * <var>y</var>, gnutls_datum_t * <var>k</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fprivkey_005fexport_005fdsa_005fraw">gnutls_x509_privkey_export_dsa_raw</a> (gnutls_x509_privkey_t <var>key</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>g</var>, gnutls_datum_t * <var>y</var>, gnutls_datum_t * <var>x</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fprivkey_005fget_005fkey_005fid">gnutls_x509_privkey_get_key_id</a> (gnutls_x509_privkey_t <var>key</var>, unsigned int <var>flags</var>, unsigned char * <var>output_data</var>, size_t * <var>output_data_size</var>)</code></dt>
</dl>

<hr>
<a name="Verifying-X_002e509-certificate-paths"></a>
<div class="header">
<p>
Next: <a href="#Verifying-a-certificate-in-the-context-of-TLS-session" accesskey="n" rel="next">Verifying a certificate in the context of TLS session</a>, Previous: <a href="#X_002e509-public-and-private-keys" accesskey="p" rel="prev">X.509 public and private keys</a>, Up: <a href="#X_002e509-certificates" accesskey="u" rel="up">X.509 certificates</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Verifying-X_002e509-certificate-paths-1"></a>
<h4 class="subsubsection">4.1.1.7 Verifying <acronym>X.509</acronym> certificate paths</h4>
<a name="index-verifying-certificate-paths"></a>

<p>Verifying certificate paths is important in <acronym>X.509</acronym>
authentication. For this purpose the following functions are
provided.
</p>




<dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005fcas"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_cas</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const gnutls_x509_crt_t * <var>clist</var>, unsigned <var>clist_size</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>clist</var>: A list of CAs
</p>
<p><var>clist_size</var>: The length of the CA list
</p>
<p><var>flags</var>: should be 0 or an or&rsquo;ed sequence of <code>GNUTLS_TL</code>  options.
</p>
<p>This function will add the given certificate authorities
to the trusted list. The list of CAs must not be deinitialized
during this structure&rsquo;s lifetime.
</p>
<p>If the flag <code>GNUTLS_TL_NO_DUPLICATES</code>  is specified, then
the provided  <code>clist</code> entries that are duplicates will not be
added to the list and will be deinitialized.
</p>
<p><strong>Returns:</strong> The number of added elements is returned.
</p>
<p><strong>Since:</strong> 3.0.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005fnamed_005fcrt"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_named_crt</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, gnutls_x509_crt_t <var>cert</var>, const void * <var>name</var>, size_t <var>name_size</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>cert</var>: A certificate
</p>
<p><var>name</var>: An identifier for the certificate
</p>
<p><var>name_size</var>: The size of the identifier
</p>
<p><var>flags</var>: should be 0.
</p>
<p>This function will add the given certificate to the trusted
list and associate it with a name. The certificate will not be
be used for verification with <code>gnutls_x509_trust_list_verify_crt()</code> 
but with <code>gnutls_x509_trust_list_verify_named_crt()</code>  or
<code>gnutls_x509_trust_list_verify_crt2()</code>  - the latter only since
GnuTLS 3.4.0 and if a hostname is provided.
</p>
<p>In principle this function can be used to set individual &quot;server&quot;
certificates that are trusted by the user for that specific server
but for no other purposes.
</p>
<p>The certificate must not be deinitialized during the lifetime
of the trusted list.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005fcrls"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_crls</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const gnutls_x509_crl_t * <var>crl_list</var>, int <var>crl_size</var>, unsigned int <var>flags</var>, unsigned int <var>verification_flags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>crl_list</var>: A list of CRLs
</p>
<p><var>crl_size</var>: The length of the CRL list
</p>
<p><var>flags</var>: if GNUTLS_TL_VERIFY_CRL is given the CRLs will be verified before being added.
</p>
<p><var>verification_flags</var>: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL
</p>
<p>This function will add the given certificate revocation lists
to the trusted list. The list of CRLs must not be deinitialized
during this structure&rsquo;s lifetime.
</p>
<p>This function must be called after <code>gnutls_x509_trust_list_add_cas()</code> 
to allow verifying the CRLs for validity. If the flag <code>GNUTLS_TL_NO_DUPLICATES</code> 
is given, then any provided CRLs that are a duplicate, will be deinitialized
and not added to the list (that assumes that <code>gnutls_x509_trust_list_deinit()</code> 
will be called with all=1).
</p>
<p><strong>Returns:</strong> The number of added elements is returned.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_verify_crt</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, gnutls_x509_crt_t * <var>cert_list</var>, unsigned int <var>cert_list_size</var>, unsigned int <var>flags</var>, unsigned int * <var>voutput</var>, gnutls_verify_output_function <var>func</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>cert_list</var>: is the certificate list to be verified
</p>
<p><var>cert_list_size</var>: is the certificate list size
</p>
<p><var>flags</var>: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.
</p>
<p><var>voutput</var>: will hold the certificate verification output.
</p>
<p><var>func</var>: If non-null will be called on each chain element verification with the output.
</p>
<p>This function will try to verify the given certificate and return
its status. The  <code>voutput</code> parameter will hold an OR&rsquo;ed sequence of
<code>gnutls_certificate_status_t</code>  flags.
</p>
<p>The details of the verification are the same as in <code>gnutls_x509_trust_list_verify_crt2()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt2"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_verify_crt2</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, gnutls_x509_crt_t * <var>cert_list</var>, unsigned int <var>cert_list_size</var>, gnutls_typed_vdata_st * <var>data</var>, unsigned int <var>elements</var>, unsigned int <var>flags</var>, unsigned int * <var>voutput</var>, gnutls_verify_output_function <var>func</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>cert_list</var>: is the certificate list to be verified
</p>
<p><var>cert_list_size</var>: is the certificate list size
</p>
<p><var>data</var>: an array of typed data
</p>
<p><var>elements</var>: the number of data elements
</p>
<p><var>flags</var>: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.
</p>
<p><var>voutput</var>: will hold the certificate verification output.
</p>
<p><var>func</var>: If non-null will be called on each chain element verification with the output.
</p>
<p>This function will attempt to verify the given certificate and return
its status. The  <code>voutput</code> parameter will hold an OR&rsquo;ed sequence of
<code>gnutls_certificate_status_t</code>  flags. When a chain of  <code>cert_list_size</code> with 
more than one certificates is provided, the verification status will apply
to the first certificate in the chain that failed verification. The
verification process starts from the end of the chain (from CA to end
certificate).
</p>
<p>Additionally a certificate verification profile can be specified
from the ones in <code>gnutls_certificate_verification_profiles_t</code>  by
ORing the result of <code>GNUTLS_PROFILE_TO_VFLAGS()</code>  to the verification
flags.
</p>
<p>The acceptable  <code>data</code> types are <code>GNUTLS_DT_DNS_HOSTNAME</code>  and <code>GNUTLS_DT_KEY_PURPOSE_OID</code> .
The former accepts as data a null-terminated hostname, and the latter a null-terminated
object identifier (e.g., <code>GNUTLS_KP_TLS_WWW_SERVER</code> ).
If a DNS hostname is provided then this function will compare
the hostname in the certificate against the given. If names do not match the 
<code>GNUTLS_CERT_UNEXPECTED_OWNER</code>  status flag will be set. In addition it
will consider certificates provided with <code>gnutls_x509_trust_list_add_named_crt()</code> .
</p>
<p>If a key purpose OID is provided and the end-certificate contains the extended key
usage PKIX extension, it will be required to match the provided OID
or be marked for any purpose, otherwise verification will fail with 
<code>GNUTLS_CERT_PURPOSE_MISMATCH</code>  status.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. Note that verification failure will not result to an
error code, only  <code>voutput</code> will be updated.
</p>
<p><strong>Since:</strong> 3.3.8
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fverify_005fnamed_005fcrt"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_verify_named_crt</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, gnutls_x509_crt_t <var>cert</var>, const void * <var>name</var>, size_t <var>name_size</var>, unsigned int <var>flags</var>, unsigned int * <var>voutput</var>, gnutls_verify_output_function <var>func</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>cert</var>: is the certificate to be verified
</p>
<p><var>name</var>: is the certificate&rsquo;s name
</p>
<p><var>name_size</var>: is the certificate&rsquo;s name size
</p>
<p><var>flags</var>: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.
</p>
<p><var>voutput</var>: will hold the certificate verification output.
</p>
<p><var>func</var>: If non-null will be called on each chain element verification with the output.
</p>
<p>This function will try to find a certificate that is associated with the provided
name &ndash;see <code>gnutls_x509_trust_list_add_named_crt()</code> . If a match is found the
certificate is considered valid. In addition to that this function will also 
check CRLs. The  <code>voutput</code> parameter will hold an OR&rsquo;ed sequence of 
<code>gnutls_certificate_status_t</code>  flags.
</p>
<p>Additionally a certificate verification profile can be specified
from the ones in <code>gnutls_certificate_verification_profiles_t</code>  by
ORing the result of <code>GNUTLS_PROFILE_TO_VFLAGS()</code>  to the verification
flags.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0.0
</p></dd></dl>





<dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005ffile"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_trust_file</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const char * <var>ca_file</var>, const char * <var>crl_file</var>, gnutls_x509_crt_fmt_t <var>type</var>, unsigned int <var>tl_flags</var>, unsigned int <var>tl_vflags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>ca_file</var>: A file containing a list of CAs (optional)
</p>
<p><var>crl_file</var>: A file containing a list of CRLs (optional)
</p>
<p><var>type</var>: The format of the certificates
</p>
<p><var>tl_flags</var>: GNUTLS_TL_*
</p>
<p><var>tl_vflags</var>: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL
</p>
<p>This function will add the given certificate authorities
to the trusted list. PKCS <code>11</code>  URLs are also accepted, instead
of files, by this function. A PKCS <code>11</code>  URL implies a trust
database (a specially marked module in p11-kit); the URL &quot;pkcs11:&quot;
implies all trust databases in the system. Only a single URL specifying
trust databases can be set; they cannot be stacked with multiple calls.
</p>
<p><strong>Returns:</strong> The number of added elements is returned.
</p>
<p><strong>Since:</strong> 3.1
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005fmem"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_trust_mem</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const gnutls_datum_t * <var>cas</var>, const gnutls_datum_t * <var>crls</var>, gnutls_x509_crt_fmt_t <var>type</var>, unsigned int <var>tl_flags</var>, unsigned int <var>tl_vflags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>cas</var>: A buffer containing a list of CAs (optional)
</p>
<p><var>crls</var>: A buffer containing a list of CRLs (optional)
</p>
<p><var>type</var>: The format of the certificates
</p>
<p><var>tl_flags</var>: GNUTLS_TL_*
</p>
<p><var>tl_vflags</var>: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL
</p>
<p>This function will add the given certificate authorities
to the trusted list. 
</p>
<p><strong>Returns:</strong> The number of added elements is returned.
</p>
<p><strong>Since:</strong> 3.1
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005fsystem_005ftrust"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_system_trust</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, unsigned int <var>tl_flags</var>, unsigned int <var>tl_vflags</var>)</em></dt>
<dd><p><var>list</var>: The structure of the list
</p>
<p><var>tl_flags</var>: GNUTLS_TL_*
</p>
<p><var>tl_vflags</var>: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL
</p>
<p>This function adds the system&rsquo;s default trusted certificate
authorities to the trusted list. Note that on unsupported systems
this function returns <code>GNUTLS_E_UNIMPLEMENTED_FEATURE</code> .
</p>
<p>This function implies the flag <code>GNUTLS_TL_NO_DUPLICATES</code> .
</p>
<p><strong>Returns:</strong> The number of added elements or a negative error code on error.
</p>
<p><strong>Since:</strong> 3.1
</p></dd></dl>

<p>The verification function will verify a given certificate chain against a list of certificate
authorities and certificate revocation lists, and output
a bit-wise OR of elements of the <code>gnutls_certificate_status_t</code> 
enumeration shown in <a href="#gnutls_005fcertificate_005fstatus_005ft">Figure 4.2</a>. The <code>GNUTLS_CERT_INVALID</code> flag
is always set on a verification error and more detailed flags will also be set when appropriate.
</p>
<div class="float"><a name="gnutls_005fcertificate_005fstatus_005ft"></a>


<dl compact="compact">
<dt><code>GNUTLS_CERT_INVALID</code></dt>
<dd><p>The certificate is not signed by one of the
known authorities or the signature is invalid (deprecated by the flags 
<code>GNUTLS_CERT_SIGNATURE_FAILURE</code>  and <code>GNUTLS_CERT_SIGNER_NOT_FOUND</code> ).
</p></dd>
<dt><code>GNUTLS_CERT_REVOKED</code></dt>
<dd><p>Certificate is revoked by its authority.  In X.509 this will be
set only if CRLs are checked.
</p></dd>
<dt><code>GNUTLS_CERT_SIGNER_NOT_FOUND</code></dt>
<dd><p>The certificate&rsquo;s issuer is not known. 
This is the case if the issuer is not included in the trusted certificate list.
</p></dd>
<dt><code>GNUTLS_CERT_SIGNER_NOT_CA</code></dt>
<dd><p>The certificate&rsquo;s signer was not a CA. This
may happen if this was a version 1 certificate, which is common with 
some CAs, or a version 3 certificate without the basic constrains extension.
</p></dd>
<dt><code>GNUTLS_CERT_INSECURE_ALGORITHM</code></dt>
<dd><p>The certificate was signed using an insecure
algorithm such as MD2 or MD5. These algorithms have been broken and
should not be trusted.
</p></dd>
<dt><code>GNUTLS_CERT_NOT_ACTIVATED</code></dt>
<dd><p>The certificate is not yet activated.
</p></dd>
<dt><code>GNUTLS_CERT_EXPIRED</code></dt>
<dd><p>The certificate has expired.
</p></dd>
<dt><code>GNUTLS_CERT_SIGNATURE_FAILURE</code></dt>
<dd><p>The signature verification failed.
</p></dd>
<dt><code>GNUTLS_CERT_REVOCATION_DATA_SUPERSEDED</code></dt>
<dd><p>The revocation data are old and have been superseded.
</p></dd>
<dt><code>GNUTLS_CERT_UNEXPECTED_OWNER</code></dt>
<dd><p>The owner is not the expected one.
</p></dd>
<dt><code>GNUTLS_CERT_REVOCATION_DATA_ISSUED_IN_FUTURE</code></dt>
<dd><p>The revocation data have a future issue date.
</p></dd>
<dt><code>GNUTLS_CERT_SIGNER_CONSTRAINTS_FAILURE</code></dt>
<dd><p>The certificate&rsquo;s signer constraints were
violated.
</p></dd>
<dt><code>GNUTLS_CERT_MISMATCH</code></dt>
<dd><p>The certificate presented isn&rsquo;t the expected one (TOFU)
</p></dd>
<dt><code>GNUTLS_CERT_PURPOSE_MISMATCH</code></dt>
<dd><p>The certificate or an intermediate does not match the intended purpose (extended key usage).
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 4.2: </strong>The <code>gnutls_certificate_status_t</code> enumeration.</p></div></div>
<p>An example of certificate verification is shown in <a href="#ex_002dverify2">ex-verify2</a>.
It is also possible to have a set of certificates that
are trusted for a particular server but not to authorize other certificates.
This purpose is served by the functions <a href="#gnutls_005fx509_005ftrust_005flist_005fadd_005fnamed_005fcrt">gnutls_x509_trust_list_add_named_crt</a> and <a href="#gnutls_005fx509_005ftrust_005flist_005fverify_005fnamed_005fcrt">gnutls_x509_trust_list_verify_named_crt</a>.
</p>
<hr>
<a name="Verifying-a-certificate-in-the-context-of-TLS-session"></a>
<div class="header">
<p>
Next: <a href="#Verification-using-PKCS11" accesskey="n" rel="next">Verification using PKCS11</a>, Previous: <a href="#Verifying-X_002e509-certificate-paths" accesskey="p" rel="prev">Verifying X.509 certificate paths</a>, Up: <a href="#X_002e509-certificates" accesskey="u" rel="up">X.509 certificates</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Verifying-a-certificate-in-the-context-of-TLS-session-1"></a>
<h4 class="subsubsection">4.1.1.8 Verifying a certificate in the context of TLS session</h4>
<a name="index-verifying-certificate-paths-1"></a>
<a name="index-gnutls_005fcertificate_005fverify_005fflags"></a>

<p>When operating in the context of a TLS session, the trusted certificate
authority list may also be set using:
</p><dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fx509_005ftrust_005ffile">gnutls_certificate_set_x509_trust_file</a> (gnutls_certificate_credentials_t            <var>cred</var>, const char * <var>cafile</var>, gnutls_x509_crt_fmt_t <var>type</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fx509_005ftrust_005fdir">gnutls_certificate_set_x509_trust_dir</a> (gnutls_certificate_credentials_t <var>cred</var>, const char * <var>ca_dir</var>, gnutls_x509_crt_fmt_t <var>type</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fx509_005fcrl_005ffile">gnutls_certificate_set_x509_crl_file</a> (gnutls_certificate_credentials_t <var>res</var>, const char * <var>crlfile</var>, gnutls_x509_crt_fmt_t <var>type</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fx509_005fsystem_005ftrust">gnutls_certificate_set_x509_system_trust</a> (gnutls_certificate_credentials_t       <var>cred</var>)</code></dt>
</dl>

<p>These functions allow the specification of the trusted certificate authorities, either
via a file, a directory or use the system-specified certificate authories. 
Unless the authorities are application specific, it is generally recommended
to use the system trust storage (see <a href="#gnutls_005fcertificate_005fset_005fx509_005fsystem_005ftrust">gnutls_certificate_set_x509_system_trust</a>).
</p>
<p>Unlike the previous section it is not required to setup a trusted list, and there
are two approaches to verify the peer&rsquo;s certificate and identity.
The recommended in GnuTLS 3.5.0 and later is via the <a href="#gnutls_005fsession_005fset_005fverify_005fcert">gnutls_session_set_verify_cert</a>,
but for older GnuTLS versions you may use an explicit callback set via
<a href="#gnutls_005fcertificate_005fset_005fverify_005ffunction">gnutls_certificate_set_verify_function</a> and then utilize
<a href="#gnutls_005fcertificate_005fverify_005fpeers3">gnutls_certificate_verify_peers3</a> for verification.
The reported verification status is identical to the verification functions described 
in the previous section.
</p>
<p>Note that in certain cases it is required to check the marked purpose of
the end certificate (e.g. <code>GNUTLS_KP_TLS_WWW_SERVER</code>); in these cases
the more advanced <a href="#gnutls_005fsession_005fset_005fverify_005fcert2">gnutls_session_set_verify_cert2</a> and
<a href="#gnutls_005fcertificate_005fverify_005fpeers">gnutls_certificate_verify_peers</a> should be used instead.
</p>
<p>There is also the possibility to pass some input to the verification
functions in the form of flags. For <a href="#gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt2">gnutls_x509_trust_list_verify_crt2</a> the
flags are passed directly, but for
<a href="#gnutls_005fcertificate_005fverify_005fpeers3">gnutls_certificate_verify_peers3</a>, the flags are set using
<a href="#gnutls_005fcertificate_005fset_005fverify_005fflags">gnutls_certificate_set_verify_flags</a>.  All the available
flags are part of the enumeration
<code>gnutls_certificate_verify_flags</code> shown in <a href="#gnutls_005fcertificate_005fverify_005fflags">Figure 4.3</a>.
</p>
<div class="float"><a name="gnutls_005fcertificate_005fverify_005fflags"></a>


<dl compact="compact">
<dt><code>GNUTLS_VERIFY_DISABLE_CA_SIGN</code></dt>
<dd><p>If set a signer does not have to be
a certificate authority. This flag should normally be disabled,
unless you know what this means.
</p></dd>
<dt><code>GNUTLS_VERIFY_DO_NOT_ALLOW_SAME</code></dt>
<dd><p>If a certificate is not signed by
anyone trusted but exists in the trusted CA list do not treat it
as trusted.
</p></dd>
<dt><code>GNUTLS_VERIFY_ALLOW_ANY_X509_V1_CA_CRT</code></dt>
<dd><p>Allow CA certificates that
have version 1 (both root and intermediate). This might be
dangerous since those haven&rsquo;t the basicConstraints
extension. 
</p></dd>
<dt><code>GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD2</code></dt>
<dd><p>Allow certificates to be signed
using the broken MD2 algorithm.
</p></dd>
<dt><code>GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD5</code></dt>
<dd><p>Allow certificates to be signed
using the broken MD5 algorithm.
</p></dd>
<dt><code>GNUTLS_VERIFY_DISABLE_TIME_CHECKS</code></dt>
<dd><p>Disable checking of activation
and expiration validity periods of certificate chains. Don&rsquo;t set
this unless you understand the security implications.
</p></dd>
<dt><code>GNUTLS_VERIFY_DISABLE_TRUSTED_TIME_CHECKS</code></dt>
<dd><p>If set a signer in the trusted
list is never checked for expiration or activation.
</p></dd>
<dt><code>GNUTLS_VERIFY_DO_NOT_ALLOW_X509_V1_CA_CRT</code></dt>
<dd><p>Do not allow trusted CA
certificates that have version 1.  This option is to be used
to deprecate all certificates of version 1.
</p></dd>
<dt><code>GNUTLS_VERIFY_DISABLE_CRL_CHECKS</code></dt>
<dd><p>Disable checking for validity
using certificate revocation lists or the available OCSP data.
</p></dd>
<dt><code>GNUTLS_VERIFY_ALLOW_UNSORTED_CHAIN</code></dt>
<dd><p>A certificate chain is tolerated
if unsorted (the case with many TLS servers out there). This is the
default since GnuTLS 3.1.4.
</p></dd>
<dt><code>GNUTLS_VERIFY_DO_NOT_ALLOW_UNSORTED_CHAIN</code></dt>
<dd><p>Do not tolerate an unsorted
certificate chain.
</p></dd>
<dt><code>GNUTLS_VERIFY_DO_NOT_ALLOW_WILDCARDS</code></dt>
<dd><p>When including a hostname
check in the verification, do not consider any wildcards.
</p></dd>
<dt><code>GNUTLS_VERIFY_USE_TLS1_RSA</code></dt>
<dd><p>This indicates that a (raw) RSA signature is provided
as in the TLS 1.0 protocol. Not all functions accept this flag.
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 4.3: </strong>The <code>gnutls_certificate_verify_flags</code> enumeration.</p></div></div>
<hr>
<a name="Verification-using-PKCS11"></a>
<div class="header">
<p>
Previous: <a href="#Verifying-a-certificate-in-the-context-of-TLS-session" accesskey="p" rel="prev">Verifying a certificate in the context of TLS session</a>, Up: <a href="#X_002e509-certificates" accesskey="u" rel="up">X.509 certificates</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Verifying-a-certificate-using-PKCS-_002311"></a>
<h4 class="subsubsection">4.1.1.9 Verifying a certificate using PKCS #11</h4>
<a name="index-verifying-certificate-with-pkcs11"></a>

<p>Some systems provide a system wide trusted certificate storage accessible using
the PKCS #11 API. That is, the trusted certificates are queried and accessed using the
PKCS #11 API, and trusted certificate properties, such as purpose, are marked using
attached extensions. One example is the p11-kit trust module<a name="DOCF8" href="#FOOT8"><sup>8</sup></a>.
</p>
<p>These special PKCS #11 modules can be used for GnuTLS certificate verification if marked as trust 
policy modules, i.e., with <code>trust-policy: yes</code> in the p11-kit module file.
The way to use them is by specifying to the file verification function (e.g., <a href="#gnutls_005fcertificate_005fset_005fx509_005ftrust_005ffile">gnutls_certificate_set_x509_trust_file</a>),
a pkcs11 URL, or simply <code>pkcs11:</code> to use all the marked with trust policy modules.
</p>
<p>The trust modules of p11-kit assign a purpose to trusted authorities using the extended
key usage object identifiers. The common purposes are shown in <a href="#tab_003apurposes">Table 4.4</a>. Note
that typically according to [<em>RFC5280</em>] the extended key usage object identifiers apply to end certificates. Their
application to CA certificates is an extension used by the trust modules.
</p>
<div class="float"><a name="tab_003apurposes"></a>
<table>
<thead><tr><th width="20%">Purpose</th><th width="20%">OID</th><th width="60%">Description</th></tr></thead>
<tr><td width="20%">GNUTLS_KP_TLS_WWW_SERVER</td><td width="20%">1.3.6.1.5.5.7.3.1</td><td width="60%">The certificate is to be used for TLS WWW authentication. When in a CA certificate, it
indicates that the CA is allowed to sign certificates for TLS WWW authentication.</td></tr>
<tr><td width="20%">GNUTLS_KP_TLS_WWW_CLIENT</td><td width="20%">1.3.6.1.5.5.7.3.2</td><td width="60%">The certificate is to be used for TLS WWW client authentication. When in a CA certificate, it
indicates that the CA is allowed to sign certificates for TLS WWW client authentication.</td></tr>
<tr><td width="20%">GNUTLS_KP_CODE_SIGNING</td><td width="20%">1.3.6.1.5.5.7.3.3</td><td width="60%">The certificate is to be used for code signing. When in a CA certificate, it
indicates that the CA is allowed to sign certificates for code signing.</td></tr>
<tr><td width="20%">GNUTLS_KP_EMAIL_PROTECTION</td><td width="20%">1.3.6.1.5.5.7.3.4</td><td width="60%">The certificate is to be used for email protection. When in a CA certificate, it
indicates that the CA is allowed to sign certificates for email users.</td></tr>
<tr><td width="20%">GNUTLS_KP_OCSP_SIGNING</td><td width="20%">1.3.6.1.5.5.7.3.9</td><td width="60%">The certificate is to be used for signing OCSP responses. When in a CA certificate, it
indicates that the CA is allowed to sign certificates which sign OCSP reponses.</td></tr>
<tr><td width="20%">GNUTLS_KP_ANY</td><td width="20%">2.5.29.37.0</td><td width="60%">The certificate is to be used for any purpose. When in a CA certificate, it
indicates that the CA is allowed to sign any kind of certificates.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 4.4: </strong>Key purpose object identifiers.</p></div></div>
<p>With such modules, it is recommended to use the verification functions <a href="#gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt2">gnutls_x509_trust_list_verify_crt2</a>,
or <a href="#gnutls_005fcertificate_005fverify_005fpeers">gnutls_certificate_verify_peers</a>, which allow to explicitly specify the key purpose. The
other verification functions which do not allow setting a purpose, would operate as if
<code>GNUTLS_KP_TLS_WWW_SERVER</code> was requested from the trusted authorities.
</p>
<hr>
<a name="OpenPGP-certificates"></a>
<div class="header">
<p>
Next: <a href="#Advanced-certificate-verification" accesskey="n" rel="next">Advanced certificate verification</a>, Previous: <a href="#X_002e509-certificates" accesskey="p" rel="prev">X.509 certificates</a>, Up: <a href="#Certificate-authentication" accesskey="u" rel="up">Certificate authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OpenPGP-certificates-1"></a>
<h4 class="subsection">4.1.2 <acronym>OpenPGP</acronym> certificates</h4>
<a name="index-OpenPGP-certificates"></a>

<p>The <acronym>OpenPGP</acronym> key authentication relies on a distributed trust
model, called the &ldquo;web of trust&rdquo;. The &ldquo;web of trust&rdquo; uses a
decentralized system of trusted introducers, which are the same as a
CA. <acronym>OpenPGP</acronym> allows anyone to sign anyone else&rsquo;s public
key. When Alice signs Bob&rsquo;s key, she is introducing Bob&rsquo;s key to
anyone who trusts Alice. If someone trusts Alice to introduce keys,
then Alice is a trusted introducer in the mind of that observer.
For example in <a href="#fig_002dopenpgp">Figure 4.4</a>, David trusts Alice to be an introducer and Alice
signed Bob&rsquo;s key thus Dave trusts Bob&rsquo;s key to be the real one.
</p>
<div class="float"><a name="fig_002dopenpgp"></a>
<img src="gnutls-pgp.png" alt="gnutls-pgp">

<div class="float-caption"><p><strong>Figure 4.4: </strong>An example of the OpenPGP trust model.</p></div></div>
<p>There are some key points that are important in that model. In the
example Alice has to sign Bob&rsquo;s key, only if she is sure that the key
belongs to Bob. Otherwise she may also make Dave falsely believe that
this is Bob&rsquo;s key. Dave has also the responsibility to know who to
trust.  This model is similar to real life relations.
</p>
<p>Just see how Charlie behaves in the previous example. Although he has
signed Bob&rsquo;s key - because he knows, somehow, that it belongs to Bob -
he does not trust Bob to be an introducer. Charlie decided to trust
only Kevin, for some reason. A reason could be that Bob is lazy
enough, and signs other people&rsquo;s keys without being sure that they
belong to the actual owner.
</p>
<div class="float"><a name="tab_003aopenpgp_002dcertificate"></a>
<table>
<thead><tr><th width="20%">Field</th><th width="70%">Description</th></tr></thead>
<tr><td width="20%">version</td><td width="70%">The field that indicates the version of the OpenPGP structure.</td></tr>
<tr><td width="20%">user ID</td><td width="70%">An RFC 2822 string that identifies the owner of the key. There may be
multiple user identifiers in a key.</td></tr>
<tr><td width="20%">public key</td><td width="70%">The main public key of the certificate.</td></tr>
<tr><td width="20%">expiration</td><td width="70%">The expiration time of the main public key.</td></tr>
<tr><td width="20%">public subkey</td><td width="70%">An additional public key of the certificate. There may be multiple subkeys
in a certificate.</td></tr>
<tr><td width="20%">public subkey expiration</td><td width="70%">The expiration time of the subkey.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 4.5: </strong>OpenPGP certificate fields.</p></div></div>

<a name="OpenPGP-certificate-structure"></a>
<h4 class="subsubsection">4.1.2.1 <acronym>OpenPGP</acronym> certificate structure</h4>

<p>In <acronym>GnuTLS</acronym> the <acronym>OpenPGP</acronym> certificate structures
[<em>RFC2440</em>] are handled using the <code>gnutls_openpgp_crt_t</code> type.
A typical certificate contains the user ID, which is an RFC 2822
mail and name address, a public key, possibly a number of additional
public keys (called subkeys), and a number of signatures. The various
fields are shown in <a href="#tab_003aopenpgp_002dcertificate">Table 4.5</a>.
</p>
<p>The additional subkeys may provide key for various different purposes,
e.g. one key to encrypt mail, and another to sign a TLS key exchange.
Each subkey is identified by a unique key ID.
The keys that are to be used in a TLS key exchange that requires
signatures are called authentication keys in the OpenPGP jargon.
The mapping of TLS key exchange methods to public keys is shown in
<a href="#tab_003aopenpgp_002dkey_002dexchange">Table 4.6</a>.
</p>
<div class="float"><a name="tab_003aopenpgp_002dkey_002dexchange"></a>
<table>
<thead><tr><th width="20%">Key exchange</th><th width="70%">Public key requirements</th></tr></thead>
<tr><td width="20%">RSA</td><td width="70%">An RSA public key that allows encryption.</td></tr>
<tr><td width="20%">DHE_RSA</td><td width="70%">An RSA public key that is marked for authentication.</td></tr>
<tr><td width="20%">ECDHE_RSA</td><td width="70%">An RSA public key that is marked for authentication.</td></tr>
<tr><td width="20%">DHE_DSS</td><td width="70%">A DSA public key that is marked for authentication.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 4.6: </strong>The types of (sub)keys required for the various TLS key exchange methods.</p></div></div>
<p>The corresponding private keys are stored in the
<code>gnutls_openpgp_privkey_t</code> type. All the prototypes for the key
handling functions can be found in <samp>gnutls/openpgp.h</samp>.
</p>
<a name="Verifying-an-OpenPGP-certificate"></a>
<h4 class="subsubsection">4.1.2.2 Verifying an <acronym>OpenPGP</acronym> certificate</h4>

<p>The verification functions of <acronym>OpenPGP</acronym> keys, included in
<acronym>GnuTLS</acronym>, are simple ones, and do not use the features of the
&ldquo;web of trust&rdquo;.  For that reason, if the verification needs are
complex, the assistance of external tools like <acronym>GnuPG</acronym> and
GPGME<a name="DOCF9" href="#FOOT9"><sup>9</sup></a> is
recommended.
</p>
<p>In GnuTLS there is a verification function for OpenPGP certificates,
the <a href="#gnutls_005fopenpgp_005fcrt_005fverify_005fring">gnutls_openpgp_crt_verify_ring</a>.  This checks an
<acronym>OpenPGP</acronym> key against a given set of public keys (keyring) and
returns the key status. The key verification status is the same as in
<acronym>X.509</acronym> certificates, although the meaning and interpretation
are different. For example an <acronym>OpenPGP</acronym> key may be valid, if
the self signature is ok, even if no signers were found.  The meaning
of verification status flags is the same as in the <acronym>X.509</acronym> certificates
(see <a href="#gnutls_005fcertificate_005fverify_005fflags">Figure 4.3</a>).
</p>




<dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fverify_005fring"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_verify_ring</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, gnutls_openpgp_keyring_t <var>keyring</var>, unsigned int <var>flags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>key</var>: the structure that holds the key.
</p>
<p><var>keyring</var>: holds the keyring to check against
</p>
<p><var>flags</var>: unused (should be 0)
</p>
<p><var>verify</var>: will hold the certificate verification output.
</p>
<p>Verify all signatures in the key, using the given set of keys
(keyring).
</p>
<p>The key verification output will be put in  <code>verify</code> and will be one
or more of the <code>gnutls_certificate_status_t</code>  enumerated elements
bitwise or&rsquo;d.
</p>
<p>Note that this function does not verify using any &quot;web of trust&quot;.
You may use GnuPG for that purpose, or any other external PGP
application.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>





<dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fverify_005fself"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_verify_self</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, unsigned int <var>flags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>key</var>: the structure that holds the key.
</p>
<p><var>flags</var>: unused (should be 0)
</p>
<p><var>verify</var>: will hold the key verification output.
</p>
<p>Verifies the self signature in the key.  The key verification
output will be put in  <code>verify</code> and will be one or more of the
gnutls_certificate_status_t enumerated elements bitwise or&rsquo;d.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="Verifying-a-certificate-in-the-context-of-a-TLS-session"></a>
<h4 class="subsubsection">4.1.2.3 Verifying a certificate in the context of a TLS session</h4>

<p>Similarly with X.509 certificates, one needs to specify
the OpenPGP keyring file in the credentials structure. The certificates
in this file will be  used by <a href="#gnutls_005fcertificate_005fverify_005fpeers3">gnutls_certificate_verify_peers3</a>
to verify the signatures in the certificate sent by the peer.
</p>




<dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fopenpgp_005fkeyring_005ffile"></a>Function: <em>int</em> <strong>gnutls_certificate_set_openpgp_keyring_file</strong> <em>(gnutls_certificate_credentials_t <var>c</var>, const char * <var>file</var>, gnutls_openpgp_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>c</var>: A certificate credentials structure
</p>
<p><var>file</var>: filename of the keyring.
</p>
<p><var>format</var>: format of keyring.
</p>
<p>The function is used to set keyrings that will be used internally
by various OpenPGP functions. For example to find a key when it
is needed for an operations. The keyring will also be used at the
verification functions.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<hr>
<a name="Advanced-certificate-verification"></a>
<div class="header">
<p>
Next: <a href="#Digital-signatures" accesskey="n" rel="next">Digital signatures</a>, Previous: <a href="#OpenPGP-certificates" accesskey="p" rel="prev">OpenPGP certificates</a>, Up: <a href="#Certificate-authentication" accesskey="u" rel="up">Certificate authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Advanced-certificate-verification-1"></a>
<h4 class="subsection">4.1.3 Advanced certificate verification</h4>
<a name="index-Certificate-verification"></a>

<p>The verification of X.509 certificates in the HTTPS and other Internet protocols is typically 
done by loading a trusted list of commercial Certificate Authorities
(see <a href="#gnutls_005fcertificate_005fset_005fx509_005fsystem_005ftrust">gnutls_certificate_set_x509_system_trust</a>), and using them as trusted anchors.
However, there are several examples (eg. the Diginotar incident) where one of these
authorities was compromised. This risk can be mitigated by using in addition to CA certificate verification,
other verification methods. In this section we list the available in GnuTLS methods.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Verifying-a-certificate-using-trust-on-first-use-authentication" accesskey="1">Verifying a certificate using trust on first use authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Verifying-a-certificate-using-DANE" accesskey="2">Verifying a certificate using DANE</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Verifying-a-certificate-using-trust-on-first-use-authentication"></a>
<div class="header">
<p>
Next: <a href="#Verifying-a-certificate-using-DANE" accesskey="n" rel="next">Verifying a certificate using DANE</a>, Up: <a href="#Advanced-certificate-verification" accesskey="u" rel="up">Advanced certificate verification</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Verifying-a-certificate-using-trust-on-first-use-authentication-1"></a>
<h4 class="subsubsection">4.1.3.1 Verifying a certificate using trust on first use authentication</h4>
<a name="index-verifying-certificate-paths-2"></a>
<a name="index-SSH_002dstyle-authentication"></a>
<a name="index-Trust-on-first-use"></a>
<a name="index-Key-pinning"></a>

<p>It is possible to use a trust on first use (TOFU) authentication 
method in GnuTLS. That is the concept used by the SSH programs, where the 
public key of the peer is not verified, or verified in an out-of-bound way,
but subsequent connections to the same peer require the public key to 
remain the same.  Such a system in combination with the typical CA 
verification of a certificate, and OCSP revocation checks,
can help to provide multiple factor verification, where a single point of
failure is not enough to compromise the system. For example a server compromise
may be detected using OCSP, and a CA compromise can be detected using
the trust on first use method.
Such a hybrid system with X.509 and trust on first use authentication is 
shown in <a href="#Simple-client-example-with-SSH_002dstyle-certificate-verification">Simple client example with SSH-style certificate verification</a>.
</p>
<p>See <a href="#Certificate-verification">Certificate verification</a> on how to use the available functionality.
</p>
<hr>
<a name="Verifying-a-certificate-using-DANE"></a>
<div class="header">
<p>
Previous: <a href="#Verifying-a-certificate-using-trust-on-first-use-authentication" accesskey="p" rel="prev">Verifying a certificate using trust on first use authentication</a>, Up: <a href="#Advanced-certificate-verification" accesskey="u" rel="up">Advanced certificate verification</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Verifying-a-certificate-using-DANE-_0028DNSSEC_0029"></a>
<h4 class="subsubsection">4.1.3.2 Verifying a certificate using DANE (DNSSEC)</h4>
<a name="index-verifying-certificate-paths-3"></a>
<a name="index-DANE"></a>
<a name="index-DNSSEC"></a>

<p>The DANE protocol is a protocol that can be used to verify TLS certificates
using the DNS (or better DNSSEC) protocols. The DNS security extensions (DNSSEC)
provide an alternative public key infrastructure to the commercial CAs that
are typically used to sign TLS certificates. The DANE protocol takes advantage
of the DNSSEC infrastructure to verify TLS certificates. This can be 
in addition to the verification by CA infrastructure or 
may even replace it where DNSSEC is fully deployed. Note however, that DNSSEC deployment is
fairly new and it would be better to use it as an additional verification
method rather than the only one.
</p>
<p>The DANE functionality is provided by the <code>libgnutls-dane</code> library that is shipped
with GnuTLS and the function prototypes are in <code>gnutls/dane.h</code>. 
See <a href="#Certificate-verification">Certificate verification</a> for information on how to use the library.
</p>
<p>Note however, that the DANE RFC mandates the verification methods
one should use in addition to the validation via DNSSEC TLSA entries.
GnuTLS doesn&rsquo;t follow that RFC requirement, and the term DANE verification
in this manual refers to the TLSA entry verification. In GnuTLS any 
other verification methods can be used (e.g., PKIX or TOFU) on top of
DANE.
</p>
<hr>
<a name="Digital-signatures"></a>
<div class="header">
<p>
Previous: <a href="#Advanced-certificate-verification" accesskey="p" rel="prev">Advanced certificate verification</a>, Up: <a href="#Certificate-authentication" accesskey="u" rel="up">Certificate authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Digital-signatures-1"></a>
<h4 class="subsection">4.1.4 Digital signatures</h4>
<a name="index-digital-signatures"></a>

<p>In this section we will provide some information about digital
signatures, how they work, and give the rationale for disabling some
of the algorithms used.
</p>
<p>Digital signatures work by using somebody&rsquo;s secret key to sign some
arbitrary data.  Then anybody else could use the public key of that
person to verify the signature.  Since the data may be arbitrary it is
not suitable input to a cryptographic digital signature algorithm. For
this reason and also for performance cryptographic hash algorithms are
used to preprocess the input to the signature algorithm. This works as
long as it is difficult enough to generate two different messages with
the same hash algorithm output. In that case the same signature could
be used as a proof for both messages. Nobody wants to sign an innocent
message of donating 1 euro to Greenpeace and find out that they
donated 1.000.000 euros to Bad Inc.
</p>
<p>For a hash algorithm to be called cryptographic the following three
requirements must hold:
</p>
<ol>
<li> Preimage resistance.
That means the algorithm must be one way and given the output of the
hash function <em>H(x)</em>, it is impossible to calculate <em>x</em>.

</li><li> 2nd preimage resistance.
That means that given a pair <em>x,y</em> with <em>y=H(x)</em> it is
impossible to calculate an <em>x'</em> such that <em>y=H(x')</em>.

</li><li> Collision resistance.
That means that it is impossible to calculate random <em>x</em> and
<em>x'</em> such <em>H(x')=H(x)</em>.
</li></ol>

<p>The last two requirements in the list are the most important in
digital signatures. These protect against somebody who would like to
generate two messages with the same hash output. When an algorithm is
considered broken usually it means that the Collision resistance of
the algorithm is less than brute force. Using the birthday paradox the
brute force attack takes
<em>2^{((hash size) / 2)}</em>
operations. Today colliding certificates using the MD5 hash algorithm
have been generated as shown in [<em>WEGER</em>].
</p>
<p>There has been cryptographic results for the SHA-1 hash algorithms as
well, although they are not yet critical.  Before 2004, MD5 had a
presumed collision strength of <em>2^{64}</em>, but it has been showed
to have a collision strength well under <em>2^{50}</em>.  As of November
2005, it is believed that SHA-1&rsquo;s collision strength is around
<em>2^{63}</em>.  We consider this sufficiently hard so that we still
support SHA-1.  We anticipate that SHA-256/386/512 will be used in
publicly-distributed certificates in the future.  When <em>2^{63}</em>
can be considered too weak compared to the computer power available
sometime in the future, SHA-1 will be disabled as well.  The collision
attacks on SHA-1 may also get better, given the new interest in tools
for creating them.
</p>
<a name="Trading-security-for-interoperability"></a>
<h4 class="subsubsection">4.1.4.1 Trading security for interoperability</h4>

<p>If you connect to a server and use GnuTLS&rsquo; functions to verify the
certificate chain, and get a <code>GNUTLS_CERT_INSECURE_ALGORITHM</code>
validation error (see <a href="#Verifying-X_002e509-certificate-paths">Verifying X.509 certificate paths</a>), it means
that somewhere in the certificate chain there is a certificate signed
using <code>RSA-MD2</code> or <code>RSA-MD5</code>.  These two digital signature
algorithms are considered broken, so GnuTLS fails verifying
the certificate.  In some situations, it may be useful to be
able to verify the certificate chain anyway, assuming an attacker did
not utilize the fact that these signatures algorithms are broken.
This section will give help on how to achieve that.
</p>
<p>It is important to know that you do not have to enable any of
the flags discussed here to be able to use trusted root CA
certificates self-signed using <code>RSA-MD2</code> or <code>RSA-MD5</code>. The
certificates in the trusted list are considered trusted irrespective
of the signature.
</p>
<p>If you are using <a href="#gnutls_005fcertificate_005fverify_005fpeers3">gnutls_certificate_verify_peers3</a> to verify the
certificate chain, you can call
<a href="#gnutls_005fcertificate_005fset_005fverify_005fflags">gnutls_certificate_set_verify_flags</a> with the flags:
</p><ul>
<li> <code>GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD2</code>
</li><li> <code>GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD5</code>
</li></ul>
<p>as in the following example:
</p>
<div class="example">
<pre class="example">  gnutls_certificate_set_verify_flags (x509cred,
                                       GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD5);
</pre></div>

<p>This will signal the verifier algorithm to enable <code>RSA-MD5</code> when
verifying the certificates.
</p>
<p>If you are using <a href="#gnutls_005fx509_005fcrt_005fverify">gnutls_x509_crt_verify</a> or
<a href="#gnutls_005fx509_005fcrt_005flist_005fverify">gnutls_x509_crt_list_verify</a>, you can pass the
<code>GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD5</code> parameter directly in the
<code>flags</code> parameter.
</p>
<p>If you are using these flags, it may also be a good idea to warn the
user when verification failure occur for this reason.  The simplest is
to not use the flags by default, and only fall back to using them
after warning the user.  If you wish to inspect the certificate chain
yourself, you can use <a href="#gnutls_005fcertificate_005fget_005fpeers">gnutls_certificate_get_peers</a> to extract
the raw server&rsquo;s certificate chain, <a href="#gnutls_005fx509_005fcrt_005flist_005fimport">gnutls_x509_crt_list_import</a> to parse each of the certificates, and
then <a href="#gnutls_005fx509_005fcrt_005fget_005fsignature_005falgorithm">gnutls_x509_crt_get_signature_algorithm</a> to find out the
signing algorithm used for each certificate.  If any of the
intermediary certificates are using <code>GNUTLS_SIGN_RSA_MD2</code> or
<code>GNUTLS_SIGN_RSA_MD5</code>, you could present a warning.
</p>
<hr>
<a name="More-on-certificate-authentication"></a>
<div class="header">
<p>
Next: <a href="#Shared_002dkey-and-anonymous-authentication" accesskey="n" rel="next">Shared-key and anonymous authentication</a>, Previous: <a href="#Certificate-authentication" accesskey="p" rel="prev">Certificate authentication</a>, Up: <a href="#Authentication-methods" accesskey="u" rel="up">Authentication methods</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="More-on-certificate-authentication-1"></a>
<h3 class="section">4.2 More on certificate authentication</h3>
<a name="index-certificate-authentication-1"></a>

<p>Certificates are not the only structures involved in a public key
infrastructure. Several other structures that are used for certificate
requests, encrypted private keys, revocation lists, GnuTLS abstract key
structures, etc., are discussed in this chapter.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#PKCS-10-certificate-requests" accesskey="1">PKCS 10 certificate requests</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#PKIX-certificate-revocation-lists" accesskey="2">PKIX certificate revocation lists</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OCSP-certificate-status-checking" accesskey="3">OCSP certificate status checking</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Managing-encrypted-keys" accesskey="4">Managing encrypted keys</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#certtool-Invocation" accesskey="5">certtool Invocation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Invoking certtool
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#ocsptool-Invocation" accesskey="6">ocsptool Invocation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Invoking ocsptool
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#danetool-Invocation" accesskey="7">danetool Invocation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Invoking danetool
</td></tr>
</table>

<hr>
<a name="PKCS-10-certificate-requests"></a>
<div class="header">
<p>
Next: <a href="#PKIX-certificate-revocation-lists" accesskey="n" rel="next">PKIX certificate revocation lists</a>, Up: <a href="#More-on-certificate-authentication" accesskey="u" rel="up">More on certificate authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="PKCS-_002310-certificate-requests"></a>
<h4 class="subsection">4.2.1 <acronym>PKCS</acronym> #10 certificate requests</h4>
<a name="index-certificate-requests"></a>
<a name="index-PKCS-_002310"></a>

<p>A certificate request is a structure, which contain information about
an applicant of a certificate service.  It usually contains a private
key, a distinguished name and secondary data such as a challenge
password. <acronym>GnuTLS</acronym> supports the requests defined in
<acronym>PKCS</acronym> #10 [<em>RFC2986</em>]. Other formats of certificate requests
are not currently supported.
</p>
<p>A certificate request can be generated by
associating it with a private key, setting the
subject&rsquo;s information and finally self signing it.
The last step ensures that the requester is in
possession of the private key.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrq_005fset_005fversion">gnutls_x509_crq_set_version</a> (gnutls_x509_crq_t <var>crq</var>, unsigned int <var>version</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrq_005fset_005fdn">gnutls_x509_crq_set_dn</a> (gnutls_x509_crq_t <var>crq</var>, const char * <var>dn</var>, const char ** <var>err</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrq_005fset_005fdn_005fby_005foid">gnutls_x509_crq_set_dn_by_oid</a> (gnutls_x509_crq_t <var>crq</var>, const char * <var>oid</var>, unsigned int <var>raw_flag</var>, const void * <var>data</var>, unsigned int <var>sizeof_data</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrq_005fset_005fkey_005fusage">gnutls_x509_crq_set_key_usage</a> (gnutls_x509_crq_t <var>crq</var>, unsigned int <var>usage</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrq_005fset_005fkey_005fpurpose_005foid">gnutls_x509_crq_set_key_purpose_oid</a> (gnutls_x509_crq_t <var>crq</var>, const void * <var>oid</var>, unsigned int <var>critical</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrq_005fset_005fbasic_005fconstraints">gnutls_x509_crq_set_basic_constraints</a> (gnutls_x509_crq_t <var>crq</var>, unsigned int <var>ca</var>, int <var>pathLenConstraint</var>)</code></dt>
</dl>

<p>The <a href="#gnutls_005fx509_005fcrq_005fset_005fkey">gnutls_x509_crq_set_key</a> and <a href="#gnutls_005fx509_005fcrq_005fsign2">gnutls_x509_crq_sign2</a> 
functions associate the request with a private key and sign it. If a 
request is to be signed with a key residing in a PKCS #11 token it is recommended to use
the signing functions shown in <a href="#Abstract-key-types">Abstract key types</a>.
</p>




<dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fkey"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_key</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_x509_privkey_t <var>key</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>key</var>: holds a private key
</p>
<p>This function will set the public parameters from the given private
key to the request.  
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fsign2"></a>Function: <em>int</em> <strong>gnutls_x509_crq_sign2</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_x509_privkey_t <var>key</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>key</var>: holds a private key
</p>
<p><var>dig</var>: The message digest to use, i.e., <code>GNUTLS_DIG_SHA1</code> 
</p>
<p><var>flags</var>: must be 0
</p>
<p>This function will sign the certificate request with a private key.
This must be the same key as the one used in
<code>gnutls_x509_crt_set_key()</code>  since a certificate request is self
signed.
</p>
<p>This must be the last step in a certificate request generation
since all the previously set parameters are now signed.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
<code>GNUTLS_E_ASN1_VALUE_NOT_FOUND</code>  is returned if you didn&rsquo;t set all
information in the certificate request (e.g., the version using
<code>gnutls_x509_crq_set_version()</code> ).
</p></dd></dl>

<p>The following example is about generating a certificate request, and a
private key. A certificate request can be later be processed by a CA
which should return a signed certificate.
</p>
<a name="ex_002dcrq"></a><pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/x509.h&gt;
#include &lt;gnutls/abstract.h&gt;
#include &lt;time.h&gt;

/* This example will generate a private key and a certificate
 * request.
 */

int main(void)
{
        gnutls_x509_crq_t crq;
        gnutls_x509_privkey_t key;
        unsigned char buffer[10 * 1024];
        size_t buffer_size = sizeof(buffer);
        unsigned int bits;

        gnutls_global_init();

        /* Initialize an empty certificate request, and
         * an empty private key.
         */
        gnutls_x509_crq_init(&amp;crq);

        gnutls_x509_privkey_init(&amp;key);

        /* Generate an RSA key of moderate security.
         */
        bits =
            gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA,
                                        GNUTLS_SEC_PARAM_MEDIUM);
        gnutls_x509_privkey_generate(key, GNUTLS_PK_RSA, bits, 0);

        /* Add stuff to the distinguished name
         */
        gnutls_x509_crq_set_dn_by_oid(crq, GNUTLS_OID_X520_COUNTRY_NAME,
                                      0, &quot;GR&quot;, 2);

        gnutls_x509_crq_set_dn_by_oid(crq, GNUTLS_OID_X520_COMMON_NAME,
                                      0, &quot;Nikos&quot;, strlen(&quot;Nikos&quot;));

        /* Set the request version.
         */
        gnutls_x509_crq_set_version(crq, 1);

        /* Set a challenge password.
         */
        gnutls_x509_crq_set_challenge_password(crq,
                                               &quot;something to remember here&quot;);

        /* Associate the request with the private key
         */
        gnutls_x509_crq_set_key(crq, key);

        /* Self sign the certificate request.
         */
        gnutls_x509_crq_sign2(crq, key, GNUTLS_DIG_SHA1, 0);

        /* Export the PEM encoded certificate request, and
         * display it.
         */
        gnutls_x509_crq_export(crq, GNUTLS_X509_FMT_PEM, buffer,
                               &amp;buffer_size);

        printf(&quot;Certificate Request: \n%s&quot;, buffer);


        /* Export the PEM encoded private key, and
         * display it.
         */
        buffer_size = sizeof(buffer);
        gnutls_x509_privkey_export(key, GNUTLS_X509_FMT_PEM, buffer,
                                   &amp;buffer_size);

        printf(&quot;\n\nPrivate key: \n%s&quot;, buffer);

        gnutls_x509_crq_deinit(crq);
        gnutls_x509_privkey_deinit(key);

        return 0;

}
</pre>
<hr>
<a name="PKIX-certificate-revocation-lists"></a>
<div class="header">
<p>
Next: <a href="#OCSP-certificate-status-checking" accesskey="n" rel="next">OCSP certificate status checking</a>, Previous: <a href="#PKCS-10-certificate-requests" accesskey="p" rel="prev">PKCS 10 certificate requests</a>, Up: <a href="#More-on-certificate-authentication" accesskey="u" rel="up">More on certificate authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="PKIX-certificate-revocation-lists-1"></a>
<h4 class="subsection">4.2.2 PKIX certificate revocation lists</h4>
<a name="index-certificate-revocation-lists"></a>
<a name="index-CRL"></a>

<p>A certificate revocation list (CRL) is a structure issued by an authority
periodically containing a list of revoked certificates serial numbers.
The CRL structure is signed with the issuing authorities&rsquo; keys. A typical
CRL contains the fields as shown in <a href="#tab_003acrl">Table 4.7</a>.
Certificate revocation lists are used to complement the expiration date of a certificate,
in order to account for other reasons of revocation, such as compromised keys, etc.
</p>
<p>Each CRL is valid for limited amount of
time and is required to provide, except for the current issuing time, also 
the issuing time of the next update.
</p>
<div class="float"><a name="tab_003acrl"></a>
<table>
<thead><tr><th width="20%">Field</th><th width="70%">Description</th></tr></thead>
<tr><td width="20%">version</td><td width="70%">The field that indicates the version of the CRL structure.</td></tr>
<tr><td width="20%">signature</td><td width="70%">A signature by the issuing authority.</td></tr>
<tr><td width="20%">issuer</td><td width="70%">Holds the issuer&rsquo;s distinguished name.</td></tr>
<tr><td width="20%">thisUpdate</td><td width="70%">The issuing time of the revocation list.</td></tr>
<tr><td width="20%">nextUpdate</td><td width="70%">The issuing time of the revocation list that will update that one.</td></tr>
<tr><td width="20%">revokedCertificates</td><td width="70%">List of revoked certificates serial numbers.</td></tr>
<tr><td width="20%">extensions</td><td width="70%">Optional CRL structure extensions.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 4.7: </strong>Certificate revocation list fields.</p></div></div>
<p>The basic CRL structure functions follow.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005finit">gnutls_x509_crl_init</a> (gnutls_x509_crl_t * <var>crl</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fimport">gnutls_x509_crl_import</a> (gnutls_x509_crl_t <var>crl</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fexport">gnutls_x509_crl_export</a> (gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_fmt_t <var>format</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fexport">gnutls_x509_crl_export</a> (gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_fmt_t <var>format</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</code></dt>
</dl>

<a name="Reading-a-CRL"></a>
<h4 class="subsubheading">Reading a CRL</h4>

<p>The most important function that extracts the certificate revocation
information from a CRL is <a href="#gnutls_005fx509_005fcrl_005fget_005fcrt_005fserial">gnutls_x509_crl_get_crt_serial</a>. Other
functions that return other fields of the CRL structure are also provided.
</p>




<dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fcrt_005fserial"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_crt_serial</strong> <em>(gnutls_x509_crl_t <var>crl</var>, int <var>indx</var>, unsigned char * <var>serial</var>, size_t * <var>serial_size</var>, time_t * <var>t</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p><var>indx</var>: the index of the certificate to extract (starting from 0)
</p>
<p><var>serial</var>: where the serial number will be copied
</p>
<p><var>serial_size</var>: initially holds the size of serial
</p>
<p><var>t</var>: if non null, will hold the time this certificate was revoked
</p>
<p>This function will retrieve the serial number of the specified, by
the index, revoked certificate.
</p>
<p>Note that this function will have performance issues in large sequences
of revoked certificates. In that case use <code>gnutls_x509_crl_iter_crt_serial()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fget_005fversion">gnutls_x509_crl_get_version</a> (gnutls_x509_crl_t <var>crl</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn">gnutls_x509_crl_get_issuer_dn</a> (const gnutls_x509_crl_t <var>crl</var>, char * <var>buf</var>, size_t * <var>sizeof_buf</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn2">gnutls_x509_crl_get_issuer_dn2</a> (gnutls_x509_crl_t <var>crl</var>, gnutls_datum_t * <var>dn</var>)</code></dt>
<dt><code><var>time_t</var> <a href="#gnutls_005fx509_005fcrl_005fget_005fthis_005fupdate">gnutls_x509_crl_get_this_update</a> (gnutls_x509_crl_t <var>crl</var>)</code></dt>
<dt><code><var>time_t</var> <a href="#gnutls_005fx509_005fcrl_005fget_005fnext_005fupdate">gnutls_x509_crl_get_next_update</a> (gnutls_x509_crl_t <var>crl</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fget_005fcrt_005fcount">gnutls_x509_crl_get_crt_count</a> (gnutls_x509_crl_t <var>crl</var>)</code></dt>
</dl>

<a name="Generation-of-a-CRL"></a>
<h4 class="subsubheading">Generation of a CRL</h4>

<p>The following functions can be used to generate a CRL.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fset_005fversion">gnutls_x509_crl_set_version</a> (gnutls_x509_crl_t <var>crl</var>, unsigned int <var>version</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fset_005fcrt_005fserial">gnutls_x509_crl_set_crt_serial</a> (gnutls_x509_crl_t <var>crl</var>, const void * <var>serial</var>, size_t <var>serial_size</var>, time_t <var>revocation_time</var>)</code></dt>
</dl>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fset_005fcrt">gnutls_x509_crl_set_crt</a> (gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_t <var>crt</var>, time_t <var>revocation_time</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fset_005fnext_005fupdate">gnutls_x509_crl_set_next_update</a> (gnutls_x509_crl_t <var>crl</var>, time_t <var>exp_time</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fset_005fthis_005fupdate">gnutls_x509_crl_set_this_update</a> (gnutls_x509_crl_t <var>crl</var>, time_t <var>act_time</var>)</code></dt>
</dl>

<p>The <a href="#gnutls_005fx509_005fcrl_005fsign2">gnutls_x509_crl_sign2</a> and <a href="#gnutls_005fx509_005fcrl_005fprivkey_005fsign">gnutls_x509_crl_privkey_sign</a> 
functions sign the revocation list with a private key. The latter function
can be used to sign with a key residing in a PKCS #11 token.
</p>




<dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fsign2"></a>Function: <em>int</em> <strong>gnutls_x509_crl_sign2</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_t <var>issuer</var>, gnutls_x509_privkey_t <var>issuer_key</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>issuer</var>: is the certificate of the certificate issuer
</p>
<p><var>issuer_key</var>: holds the issuer&rsquo;s private key
</p>
<p><var>dig</var>: The message digest to use. GNUTLS_DIG_SHA1 is the safe choice unless you know what you&rsquo;re doing.
</p>
<p><var>flags</var>: must be 0
</p>
<p>This function will sign the CRL with the issuer&rsquo;s private key, and
will copy the issuer&rsquo;s information into the CRL.
</p>
<p>This must be the last step in a certificate CRL since all
the previously set parameters are now signed.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fprivkey_005fsign"></a>Function: <em>int</em> <strong>gnutls_x509_crl_privkey_sign</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_t <var>issuer</var>, gnutls_privkey_t <var>issuer_key</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>issuer</var>: is the certificate of the certificate issuer
</p>
<p><var>issuer_key</var>: holds the issuer&rsquo;s private key
</p>
<p><var>dig</var>: The message digest to use. GNUTLS_DIG_SHA1 is the safe choice unless you know what you&rsquo;re doing.
</p>
<p><var>flags</var>: must be 0
</p>
<p>This function will sign the CRL with the issuer&rsquo;s private key, and
will copy the issuer&rsquo;s information into the CRL.
</p>
<p>This must be the last step in a certificate CRL since all
the previously set parameters are now signed.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p>Since 2.12.0
</p></dd></dl>

<p>Few extensions on the CRL structure are supported, including the
CRL number extension and the authority key identifier.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fset_005fnumber">gnutls_x509_crl_set_number</a> (gnutls_x509_crl_t <var>crl</var>, const void * <var>nr</var>, size_t <var>nr_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fset_005fauthority_005fkey_005fid">gnutls_x509_crl_set_authority_key_id</a> (gnutls_x509_crl_t <var>crl</var>, const void * <var>id</var>, size_t <var>id_size</var>)</code></dt>
</dl>

<hr>
<a name="OCSP-certificate-status-checking"></a>
<div class="header">
<p>
Next: <a href="#Managing-encrypted-keys" accesskey="n" rel="next">Managing encrypted keys</a>, Previous: <a href="#PKIX-certificate-revocation-lists" accesskey="p" rel="prev">PKIX certificate revocation lists</a>, Up: <a href="#More-on-certificate-authentication" accesskey="u" rel="up">More on certificate authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OCSP-certificate-status-checking-1"></a>
<h4 class="subsection">4.2.3 <acronym>OCSP</acronym> certificate status checking</h4>
<a name="index-certificate-status"></a>
<a name="index-Online-Certificate-Status-Protocol"></a>
<a name="index-OCSP"></a>

<p>Certificates may be revoked before their expiration time has been
reached.  There are several reasons for revoking certificates, but a
typical situation is when the private key associated with a
certificate has been compromised.  Traditionally, Certificate
Revocation Lists (CRLs) have been used by application to implement
revocation checking, however, several problems with CRLs have been
identified [<em>RIVESTCRL</em>].
</p>
<p>The Online Certificate Status Protocol, or <acronym>OCSP</acronym> [<em>RFC2560</em>], 
is a widely implemented protocol which performs certificate revocation status
checking.  An application that wish to verify the
identity of a peer will verify the certificate against a set of
trusted certificates and then check whether the certificate is listed
in a CRL and/or perform an OCSP check for the certificate.
</p>
<p>Note that in the context of a TLS session the server may provide an
OCSP response that will be used during the TLS certificate verification
(see <a href="#gnutls_005fcertificate_005fverify_005fpeers2">gnutls_certificate_verify_peers2</a>).
You may obtain this response using <a href="#gnutls_005focsp_005fstatus_005frequest_005fget">gnutls_ocsp_status_request_get</a>.
</p>
<p>Before performing the OCSP query, the application will need to figure
out the address of the OCSP server.  The OCSP server address can be
provided by the local user in manual configuration or may be stored
in the certificate that is being checked.  When stored in a certificate
the OCSP server is in the extension field called the Authority Information 
Access (AIA). The following function
extracts this information from a certificate.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fget_005fauthority_005finfo_005faccess">gnutls_x509_crt_get_authority_info_access</a> (gnutls_x509_crt_t <var>crt</var>, unsigned int <var>seq</var>, int <var>what</var>, gnutls_datum_t * <var>data</var>, unsigned int * <var>critical</var>)</code></dt>
</dl>

<p>There are several functions in GnuTLS for creating and manipulating
OCSP requests and responses.  The general idea is that a client
application creates an OCSP request object, stores some information
about the certificate to check in the request, and then exports the
request in DER format.  The request will then need to be sent to the
OCSP responder, which needs to be done by the application (GnuTLS does
not send and receive OCSP packets).  Normally an OCSP response is
received that the application will need to import into an OCSP
response object.  The digital signature in the OCSP response needs to
be verified against a set of trust anchors before the information in
the response can be trusted.
</p>
<p>The ASN.1 structure of OCSP requests are briefly as follows.  It is
useful to review the structures to get an understanding of which
fields are modified by GnuTLS functions.
</p>
<div class="example">
<pre class="example">OCSPRequest     ::=     SEQUENCE {
    tbsRequest                  TBSRequest,
    optionalSignature   [0]     EXPLICIT Signature OPTIONAL }

TBSRequest      ::=     SEQUENCE {
    version             [0]     EXPLICIT Version DEFAULT v1,
    requestorName       [1]     EXPLICIT GeneralName OPTIONAL,
    requestList                 SEQUENCE OF Request,
    requestExtensions   [2]     EXPLICIT Extensions OPTIONAL }

Request         ::=     SEQUENCE {
    reqCert                     CertID,
    singleRequestExtensions     [0] EXPLICIT Extensions OPTIONAL }

CertID          ::=     SEQUENCE {
    hashAlgorithm       AlgorithmIdentifier,
    issuerNameHash      OCTET STRING, -- Hash of Issuer's DN
    issuerKeyHash       OCTET STRING, -- Hash of Issuers public key
    serialNumber        CertificateSerialNumber }
</pre></div>

<p>The basic functions to initialize, import, export and deallocate OCSP
requests are the following.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005focsp_005freq_005finit">gnutls_ocsp_req_init</a> (gnutls_ocsp_req_t * <var>req</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005focsp_005freq_005fdeinit">gnutls_ocsp_req_deinit</a> (gnutls_ocsp_req_t <var>req</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005freq_005fimport">gnutls_ocsp_req_import</a> (gnutls_ocsp_req_t <var>req</var>, const gnutls_datum_t * <var>data</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005freq_005fexport">gnutls_ocsp_req_export</a> (gnutls_ocsp_req_t <var>req</var>, gnutls_datum_t * <var>data</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005freq_005fprint">gnutls_ocsp_req_print</a> (gnutls_ocsp_req_t <var>req</var>, gnutls_ocsp_print_formats_t <var>format</var>, gnutls_datum_t * <var>out</var>)</code></dt>
</dl>

<p>To generate an OCSP request the issuer name hash, issuer key hash, and 
the checked certificate&rsquo;s serial number are required. There are two
interfaces available for setting those in an OCSP request.
The is a low-level function when you have the
issuer name hash, issuer key hash, and certificate serial number in
binary form.  The second is more useful if you have the
certificate (and its issuer) in a <code>gnutls_x509_crt_t</code> type.
There is also a function to extract this information from existing an OCSP
request.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005focsp_005freq_005fadd_005fcert_005fid">gnutls_ocsp_req_add_cert_id</a> (gnutls_ocsp_req_t <var>req</var>, gnutls_digest_algorithm_t <var>digest</var>, const gnutls_datum_t * <var>issuer_name_hash</var>, const gnutls_datum_t * <var>issuer_key_hash</var>, const gnutls_datum_t * <var>serial_number</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005freq_005fadd_005fcert">gnutls_ocsp_req_add_cert</a> (gnutls_ocsp_req_t <var>req</var>, gnutls_digest_algorithm_t <var>digest</var>, gnutls_x509_crt_t <var>issuer</var>, gnutls_x509_crt_t <var>cert</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005freq_005fget_005fcert_005fid">gnutls_ocsp_req_get_cert_id</a> (gnutls_ocsp_req_t <var>req</var>, unsigned <var>indx</var>, gnutls_digest_algorithm_t * <var>digest</var>, gnutls_datum_t * <var>issuer_name_hash</var>, gnutls_datum_t * <var>issuer_key_hash</var>, gnutls_datum_t * <var>serial_number</var>)</code></dt>
</dl>

<p>Each OCSP request may contain a number of extensions.  Extensions are
identified by an Object Identifier (OID) and an opaque data buffer
whose syntax and semantics is implied by the OID. You can extract or
set those extensions using the following functions.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005focsp_005freq_005fget_005fextension">gnutls_ocsp_req_get_extension</a> (gnutls_ocsp_req_t <var>req</var>, unsigned <var>indx</var>, gnutls_datum_t * <var>oid</var>, unsigned int * <var>critical</var>, gnutls_datum_t * <var>data</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005freq_005fset_005fextension">gnutls_ocsp_req_set_extension</a> (gnutls_ocsp_req_t <var>req</var>, const char * <var>oid</var>, unsigned int <var>critical</var>, const gnutls_datum_t * <var>data</var>)</code></dt>
</dl>

<p>A common OCSP Request extension is the nonce extension (OID
1.3.6.1.5.5.7.48.1.2), which is used to avoid replay attacks of
earlier recorded OCSP responses.  The nonce extension carries a value
that is intended to be sufficiently random and unique so that an
attacker will not be able to give a stale response for the same nonce.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005focsp_005freq_005fget_005fnonce">gnutls_ocsp_req_get_nonce</a> (gnutls_ocsp_req_t <var>req</var>, unsigned int * <var>critical</var>, gnutls_datum_t * <var>nonce</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005freq_005fset_005fnonce">gnutls_ocsp_req_set_nonce</a> (gnutls_ocsp_req_t <var>req</var>, unsigned int <var>critical</var>, const gnutls_datum_t * <var>nonce</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005freq_005frandomize_005fnonce">gnutls_ocsp_req_randomize_nonce</a> (gnutls_ocsp_req_t <var>req</var>)</code></dt>
</dl>

<p>The OCSP response structures is a complex structure. A simplified overview
of it is in <a href="#tab_003aocsp_002dresponse">Table 4.8</a>. Note that a response may contain 
information on multiple certificates.
</p>
<div class="float"><a name="tab_003aocsp_002dresponse"></a>
<table>
<thead><tr><th width="20%">Field</th><th width="70%">Description</th></tr></thead>
<tr><td width="20%">version</td><td width="70%">The OCSP response version number (typically 1).</td></tr>
<tr><td width="20%">responder ID</td><td width="70%">An identifier of the responder (DN name or a hash of its key).</td></tr>
<tr><td width="20%">issue time</td><td width="70%">The time the response was generated.</td></tr>
<tr><td width="20%">thisUpdate</td><td width="70%">The issuing time of the revocation information.</td></tr>
<tr><td width="20%">nextUpdate</td><td width="70%">The issuing time of the revocation information that will update that one.</td></tr>
<tr><td width="20%"></td><td width="70%">Revoked certificates</td></tr>
<tr><td width="20%">certificate status</td><td width="70%">The status of the certificate.</td></tr>
<tr><td width="20%">certificate serial</td><td width="70%">The certificate&rsquo;s serial number.</td></tr>
<tr><td width="20%">revocationTime</td><td width="70%">The time the certificate was revoked.</td></tr>
<tr><td width="20%">revocationReason</td><td width="70%">The reason the certificate was revoked.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 4.8: </strong>The most important OCSP response fields.</p></div></div>

<p>We provide basic functions for initialization, importing, exporting
and deallocating OCSP responses.  
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005focsp_005fresp_005finit">gnutls_ocsp_resp_init</a> (gnutls_ocsp_resp_t * <var>resp</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005focsp_005fresp_005fdeinit">gnutls_ocsp_resp_deinit</a> (gnutls_ocsp_resp_t <var>resp</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005fresp_005fimport">gnutls_ocsp_resp_import</a> (gnutls_ocsp_resp_t <var>resp</var>, const gnutls_datum_t * <var>data</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005fresp_005fexport">gnutls_ocsp_resp_export</a> (gnutls_ocsp_resp_t <var>resp</var>, gnutls_datum_t * <var>data</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005fresp_005fprint">gnutls_ocsp_resp_print</a> (gnutls_ocsp_resp_t <var>resp</var>, gnutls_ocsp_print_formats_t <var>format</var>, gnutls_datum_t * <var>out</var>)</code></dt>
</dl>

<p>The utility function that extracts the revocation as well as other information
from a response is shown below.
</p>




<dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fsingle"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_get_single</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, unsigned <var>indx</var>, gnutls_digest_algorithm_t * <var>digest</var>, gnutls_datum_t * <var>issuer_name_hash</var>, gnutls_datum_t * <var>issuer_key_hash</var>, gnutls_datum_t * <var>serial_number</var>, unsigned int * <var>cert_status</var>, time_t * <var>this_update</var>, time_t * <var>next_update</var>, time_t * <var>revocation_time</var>, unsigned int * <var>revocation_reason</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p><var>indx</var>: Specifies response number to get. Use (0) to get the first one.
</p>
<p><var>digest</var>: output variable with <code>gnutls_digest_algorithm_t</code>  hash algorithm
</p>
<p><var>issuer_name_hash</var>: output buffer with hash of issuer&rsquo;s DN
</p>
<p><var>issuer_key_hash</var>: output buffer with hash of issuer&rsquo;s public key
</p>
<p><var>serial_number</var>: output buffer with serial number of certificate to check
</p>
<p><var>cert_status</var>: a certificate status, a <code>gnutls_ocsp_cert_status_t</code>  enum.
</p>
<p><var>this_update</var>: time at which the status is known to be correct.
</p>
<p><var>next_update</var>: when newer information will be available, or (time_t)-1 if unspecified
</p>
<p><var>revocation_time</var>: when  <code>cert_status</code> is <code>GNUTLS_OCSP_CERT_REVOKED</code> , holds time of revocation.
</p>
<p><var>revocation_reason</var>: revocation reason, a <code>gnutls_x509_crl_reason_t</code>  enum.
</p>
<p>This function will return the certificate information of the
 <code>indx</code> &rsquo;ed response in the Basic OCSP Response  <code>resp</code> .  The
information returned corresponds to the OCSP SingleResponse structure
except the final singleExtensions.
</p>
<p>Each of the pointers to output variables may be NULL to indicate
that the caller is not interested in that value.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.  If you have reached the last
CertID available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be
returned.
</p></dd></dl>

<p>The possible revocation reasons available in an OCSP response are shown
below.
</p>
<div class="float"><a name="gnutls_005fx509_005fcrl_005freason_005ft"></a>


<dl compact="compact">
<dt><code>GNUTLS_X509_CRLREASON_UNSPECIFIED</code></dt>
<dd><p>Unspecified reason.
</p></dd>
<dt><code>GNUTLS_X509_CRLREASON_KEYCOMPROMISE</code></dt>
<dd><p>Private key compromised.
</p></dd>
<dt><code>GNUTLS_X509_CRLREASON_CACOMPROMISE</code></dt>
<dd><p>CA compromised.
</p></dd>
<dt><code>GNUTLS_X509_CRLREASON_AFFILIATIONCHANGED</code></dt>
<dd><p>Affiliation has changed.
</p></dd>
<dt><code>GNUTLS_X509_CRLREASON_SUPERSEDED</code></dt>
<dd><p>Certificate superseded.
</p></dd>
<dt><code>GNUTLS_X509_CRLREASON_CESSATIONOFOPERATION</code></dt>
<dd><p>Operation has ceased.
</p></dd>
<dt><code>GNUTLS_X509_CRLREASON_CERTIFICATEHOLD</code></dt>
<dd><p>Certificate is on hold.
</p></dd>
<dt><code>GNUTLS_X509_CRLREASON_REMOVEFROMCRL</code></dt>
<dd><p>Will be removed from delta CRL.
</p></dd>
<dt><code>GNUTLS_X509_CRLREASON_PRIVILEGEWITHDRAWN</code></dt>
<dd><p>Privilege withdrawn.
</p></dd>
<dt><code>GNUTLS_X509_CRLREASON_AACOMPROMISE</code></dt>
<dd><p>AA compromised.
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 4.5: </strong>The revocation reasons</p></div></div>
<p>Note, that the OCSP response needs to be verified against some set of trust
anchors before it can be relied upon. It is also important to check
whether the received OCSP response corresponds to the certificate being checked.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005focsp_005fresp_005fverify">gnutls_ocsp_resp_verify</a> (gnutls_ocsp_resp_t <var>resp</var>, gnutls_x509_trust_list_t <var>trustlist</var>, unsigned int * <var>verify</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005fresp_005fverify_005fdirect">gnutls_ocsp_resp_verify_direct</a> (gnutls_ocsp_resp_t <var>resp</var>, gnutls_x509_crt_t <var>issuer</var>, unsigned int * <var>verify</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005focsp_005fresp_005fcheck_005fcrt">gnutls_ocsp_resp_check_crt</a> (gnutls_ocsp_resp_t <var>resp</var>, unsigned int <var>indx</var>, gnutls_x509_crt_t <var>crt</var>)</code></dt>
</dl>

<hr>
<a name="Managing-encrypted-keys"></a>
<div class="header">
<p>
Next: <a href="#certtool-Invocation" accesskey="n" rel="next">certtool Invocation</a>, Previous: <a href="#OCSP-certificate-status-checking" accesskey="p" rel="prev">OCSP certificate status checking</a>, Up: <a href="#More-on-certificate-authentication" accesskey="u" rel="up">More on certificate authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Managing-encrypted-keys-1"></a>
<h4 class="subsection">4.2.4 Managing encrypted keys</h4>
<a name="index-Encrypted-keys"></a>

<p>Transferring or storing private keys in plain may not be a
good idea, since any compromise is irreparable.
Storing the keys in hardware security modules (see <a href="#Smart-cards-and-HSMs">Smart cards and HSMs</a>)
could solve the storage problem but it is not always practical
or efficient enough. This section describes ways to store and
transfer encrypted private keys.
</p>
<p>There are methods for key encryption, namely the
PKCS #8, PKCS #12 and OpenSSL&rsquo;s custom encrypted private key formats. 
The PKCS #8 and the OpenSSL&rsquo;s method allow encryption of the private key, 
while the PKCS #12 method allows, in addition, the bundling of accompanying 
data into the structure. That is typically the corresponding certificate, as 
well as a trusted CA certificate.
</p>
<a name="High-level-functionality"></a>
<h4 class="subsubheading">High level functionality</h4>
<p>Generic and higher level private key import functions are available, that
import plain or encrypted keys and will auto-detect the encrypted key format.
</p>




<dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fx509_005fraw"></a>Function: <em>int</em> <strong>gnutls_privkey_import_x509_raw</strong> <em>(gnutls_privkey_t <var>pkey</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>data</var>: The private key data to be imported
</p>
<p><var>format</var>: The format of the private key
</p>
<p><var>password</var>: A password (optional)
</p>
<p><var>flags</var>: an ORed sequence of gnutls_pkcs_encrypt_flags_t
</p>
<p>This function will import the given private key to the abstract
<code>gnutls_privkey_t</code>  type. 
</p>
<p>The supported formats are basic unencrypted key, PKCS8, PKCS12, 
and the openssl format.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>





<dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fimport2"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_import2</strong> <em>(gnutls_x509_privkey_t <var>key</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: The data to store the parsed key
</p>
<p><var>data</var>: The DER or PEM encoded key.
</p>
<p><var>format</var>: One of DER or PEM
</p>
<p><var>password</var>: A password (optional)
</p>
<p><var>flags</var>: an ORed sequence of gnutls_pkcs_encrypt_flags_t
</p>
<p>This function will import the given DER or PEM encoded key, to 
the native <code>gnutls_x509_privkey_t</code>  format, irrespective of the
input format. The input format is auto-detected.
</p>
<p>The supported formats are basic unencrypted key, PKCS8, PKCS12,
and the openssl format.
</p>
<p>If the provided key is encrypted but no password was given, then
<code>GNUTLS_E_DECRYPTION_FAILED</code>  is returned. Since GnuTLS 3.4.0 this
function will utilize the PIN callbacks if any.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<p>Any keys imported using those functions can be imported to a certificate
credentials structure using <a href="#gnutls_005fcertificate_005fset_005fkey">gnutls_certificate_set_key</a>, or alternatively
they can be directly imported using <a href="#gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile2">gnutls_certificate_set_x509_key_file2</a>.
</p>
<a name="PKCS-_00238-structures"></a>
<h4 class="subsubheading"><acronym>PKCS</acronym> #8 structures</h4>
<a name="index-PKCS-_00238"></a>

<p>PKCS #8 keys can be imported and exported as normal private keys using
the functions below. An addition to the normal import functions, are
a password and a flags argument. The flags can be any element of the <code>gnutls_pkcs_encrypt_flags_t</code>
enumeration. Note however, that GnuTLS only supports the PKCS #5 PBES2
encryption scheme. Keys encrypted with the obsolete PBES1 scheme cannot 
be decrypted.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fprivkey_005fimport_005fpkcs8">gnutls_x509_privkey_import_pkcs8</a> (gnutls_x509_privkey_t <var>key</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fprivkey_005fexport_005fpkcs8">gnutls_x509_privkey_export_pkcs8</a> (gnutls_x509_privkey_t <var>key</var>, gnutls_x509_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fprivkey_005fexport2_005fpkcs8">gnutls_x509_privkey_export2_pkcs8</a> (gnutls_x509_privkey_t <var>key</var>, gnutls_x509_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>, gnutls_datum_t * <var>out</var>)</code></dt>
</dl>

<div class="float"><a name="gnutls_005fpkcs_005fencrypt_005fflags_005ft"></a>


<dl compact="compact">
<dt><code>GNUTLS_PKCS_PLAIN</code></dt>
<dd><p>Unencrypted private key.
</p></dd>
<dt><code>GNUTLS_PKCS_PKCS12_3DES</code></dt>
<dd><p>PKCS-12 3DES.
</p></dd>
<dt><code>GNUTLS_PKCS_PKCS12_ARCFOUR</code></dt>
<dd><p>PKCS-12 ARCFOUR.
</p></dd>
<dt><code>GNUTLS_PKCS_PKCS12_RC2_40</code></dt>
<dd><p>PKCS-12 RC2-40.
</p></dd>
<dt><code>GNUTLS_PKCS_PBES2_3DES</code></dt>
<dd><p>PBES2 3DES.
</p></dd>
<dt><code>GNUTLS_PKCS_PBES2_AES_128</code></dt>
<dd><p>PBES2 AES-128.
</p></dd>
<dt><code>GNUTLS_PKCS_PBES2_AES_192</code></dt>
<dd><p>PBES2 AES-192.
</p></dd>
<dt><code>GNUTLS_PKCS_PBES2_AES_256</code></dt>
<dd><p>PBES2 AES-256.
</p></dd>
<dt><code>GNUTLS_PKCS_NULL_PASSWORD</code></dt>
<dd><p>Some schemas distinguish between an empty and a NULL password.
</p></dd>
<dt><code>GNUTLS_PKCS_PBES2_DES</code></dt>
<dd><p>PBES2 single DES.
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 4.6: </strong>Encryption flags</p></div></div>
<a name="PKCS-_002312-structures"></a>
<h4 class="subsubheading"><acronym>PKCS</acronym> #12 structures</h4>
<a name="index-PKCS-_002312"></a>

<p>A <acronym>PKCS</acronym> #12 structure [<em>PKCS12</em>] usually contains a user&rsquo;s
private keys and certificates. It is commonly used in browsers to
export and import the user&rsquo;s identities. A file containing such a key can 
be directly imported to a certificate credentials structure by using 
<a href="#gnutls_005fcertificate_005fset_005fx509_005fsimple_005fpkcs12_005ffile">gnutls_certificate_set_x509_simple_pkcs12_file</a>.
</p>
<p>In <acronym>GnuTLS</acronym> the <acronym>PKCS</acronym> #12 structures are handled
using the <code>gnutls_pkcs12_t</code> type. This is an abstract type that
may hold several <code>gnutls_pkcs12_bag_t</code> types.  The bag types are
the holders of the actual data, which may be certificates, private
keys or encrypted data.  A bag of type encrypted should be decrypted
in order for its data to be accessed.
</p>
<p>To reduce the complexity in parsing the structures the simple 
helper function <a href="#gnutls_005fpkcs12_005fsimple_005fparse">gnutls_pkcs12_simple_parse</a> is provided. For more
advanced uses, manual parsing of the structure is required using the
functions below.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fget_005fbag">gnutls_pkcs12_get_bag</a> (gnutls_pkcs12_t <var>pkcs12</var>, int <var>indx</var>, gnutls_pkcs12_bag_t <var>bag</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fverify_005fmac">gnutls_pkcs12_verify_mac</a> (gnutls_pkcs12_t <var>pkcs12</var>, const char * <var>pass</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fbag_005fdecrypt">gnutls_pkcs12_bag_decrypt</a> (gnutls_pkcs12_bag_t <var>bag</var>, const char * <var>pass</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fbag_005fget_005fcount">gnutls_pkcs12_bag_get_count</a> (gnutls_pkcs12_bag_t <var>bag</var>)</code></dt>
</dl>





<dl>
<dt><a name="index-gnutls_005fpkcs12_005fsimple_005fparse"></a>Function: <em>int</em> <strong>gnutls_pkcs12_simple_parse</strong> <em>(gnutls_pkcs12_t <var>p12</var>, const char * <var>password</var>, gnutls_x509_privkey_t * <var>key</var>, gnutls_x509_crt_t ** <var>chain</var>, unsigned int * <var>chain_len</var>, gnutls_x509_crt_t ** <var>extra_certs</var>, unsigned int * <var>extra_certs_len</var>, gnutls_x509_crl_t * <var>crl</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>p12</var>: A pkcs12 type
</p>
<p><var>password</var>: optional password used to decrypt the structure, bags and keys.
</p>
<p><var>key</var>: a structure to store the parsed private key.
</p>
<p><var>chain</var>: the corresponding to key certificate chain (may be <code>NULL</code> )
</p>
<p><var>chain_len</var>: will be updated with the number of additional (may be <code>NULL</code> )
</p>
<p><var>extra_certs</var>: optional pointer to receive an array of additional
certificates found in the PKCS12 structure (may be <code>NULL</code> ).
</p>
<p><var>extra_certs_len</var>: will be updated with the number of additional
certs (may be <code>NULL</code> ).
</p>
<p><var>crl</var>: an optional structure to store the parsed CRL (may be <code>NULL</code> ).
</p>
<p><var>flags</var>: should be zero or one of GNUTLS_PKCS12_SP_*
</p>
<p>This function parses a PKCS12 structure in  <code>pkcs12</code> and extracts the
private key, the corresponding certificate chain, any additional
certificates and a CRL.
</p>
<p>The  <code>extra_certs</code> and  <code>extra_certs_len</code> parameters are optional
and both may be set to <code>NULL</code> . If either is non-<code>NULL</code> , then both must
be set. The value for  <code>extra_certs</code> is allocated
using <code>gnutls_malloc()</code> .
</p>
<p>Encrypted PKCS12 bags and PKCS8 private keys are supported, but
only with password based security and the same password for all
operations.
</p>
<p>Note that a PKCS12 structure may contain many keys and/or certificates,
and there is no way to identify which key/certificate pair you want.
For this reason this function is useful for PKCS12 files that contain 
only one key/certificate pair and/or one CRL.
</p>
<p>If the provided structure has encrypted fields but no password
is provided then this function returns <code>GNUTLS_E_DECRYPTION_FAILED</code> .
</p>
<p>Note that normally the chain constructed does not include self signed
certificates, to comply with TLS&rsquo; requirements. If, however, the flag 
<code>GNUTLS_PKCS12_SP_INCLUDE_SELF_SIGNED</code>  is specified then
self signed certificates will be included in the chain.
</p>
<p>Prior to using this function the PKCS <code>12</code>  structure integrity must
be verified using <code>gnutls_pkcs12_verify_mac()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fbag_005fget_005fdata">gnutls_pkcs12_bag_get_data</a> (gnutls_pkcs12_bag_t <var>bag</var>, int <var>indx</var>, gnutls_datum_t * <var>data</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fbag_005fget_005fkey_005fid">gnutls_pkcs12_bag_get_key_id</a> (gnutls_pkcs12_bag_t <var>bag</var>, int <var>indx</var>, gnutls_datum_t * <var>id</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fbag_005fget_005ffriendly_005fname">gnutls_pkcs12_bag_get_friendly_name</a> (gnutls_pkcs12_bag_t <var>bag</var>, int <var>indx</var>, char ** <var>name</var>)</code></dt>
</dl>

<p>The functions below are used to generate a PKCS #12 structure. An example
of their usage is shown at <a href="#PKCS12-structure-generation-example">PKCS12 structure generation example</a>.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fset_005fbag">gnutls_pkcs12_set_bag</a> (gnutls_pkcs12_t <var>pkcs12</var>, gnutls_pkcs12_bag_t <var>bag</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fbag_005fencrypt">gnutls_pkcs12_bag_encrypt</a> (gnutls_pkcs12_bag_t <var>bag</var>, const char * <var>pass</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fgenerate_005fmac">gnutls_pkcs12_generate_mac</a> (gnutls_pkcs12_t <var>pkcs12</var>, const char * <var>pass</var>)</code></dt>
</dl>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fbag_005fset_005fdata">gnutls_pkcs12_bag_set_data</a> (gnutls_pkcs12_bag_t <var>bag</var>, gnutls_pkcs12_bag_type_t <var>type</var>, const gnutls_datum_t * <var>data</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fbag_005fset_005fcrl">gnutls_pkcs12_bag_set_crl</a> (gnutls_pkcs12_bag_t <var>bag</var>, gnutls_x509_crl_t <var>crl</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fbag_005fset_005fcrt">gnutls_pkcs12_bag_set_crt</a> (gnutls_pkcs12_bag_t <var>bag</var>, gnutls_x509_crt_t <var>crt</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fbag_005fset_005fkey_005fid">gnutls_pkcs12_bag_set_key_id</a> (gnutls_pkcs12_bag_t <var>bag</var>, int <var>indx</var>, const gnutls_datum_t * <var>id</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs12_005fbag_005fset_005ffriendly_005fname">gnutls_pkcs12_bag_set_friendly_name</a> (gnutls_pkcs12_bag_t <var>bag</var>, int <var>indx</var>, const char * <var>name</var>)</code></dt>
</dl>

<a name="OpenSSL-encrypted-keys"></a>
<h4 class="subsubheading">OpenSSL encrypted keys</h4>
<a name="index-OpenSSL-encrypted-keys"></a>
<p>Unfortunately the structures discussed in the previous sections are
not the only structures that may hold an encrypted private key. For example
the OpenSSL library offers a custom key encryption method. Those structures
are also supported in GnuTLS with <a href="#gnutls_005fx509_005fprivkey_005fimport_005fopenssl">gnutls_x509_privkey_import_openssl</a>.
</p>




<dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fimport_005fopenssl"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_import_openssl</strong> <em>(gnutls_x509_privkey_t <var>key</var>, const gnutls_datum_t * <var>data</var>, const char * <var>password</var>)</em></dt>
<dd><p><var>key</var>: The data to store the parsed key
</p>
<p><var>data</var>: The DER or PEM encoded key.
</p>
<p><var>password</var>: the password to decrypt the key (if it is encrypted).
</p>
<p>This function will convert the given PEM encrypted to 
the native gnutls_x509_privkey_t format. The
output will be stored in  <code>key</code> .  
</p>
<p>The  <code>password</code> should be in ASCII. If the password is not provided
or wrong then <code>GNUTLS_E_DECRYPTION_FAILED</code>  will be returned.
</p>
<p>If the Certificate is PEM encoded it should have a header of
&quot;PRIVATE KEY&quot; and the &quot;DEK-Info&quot; header. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<hr>
<a name="certtool-Invocation"></a>
<div class="header">
<p>
Next: <a href="#ocsptool-Invocation" accesskey="n" rel="next">ocsptool Invocation</a>, Previous: <a href="#Managing-encrypted-keys" accesskey="p" rel="prev">Managing encrypted keys</a>, Up: <a href="#More-on-certificate-authentication" accesskey="u" rel="up">More on certificate authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Invoking-certtool"></a>
<h4 class="subsection">4.2.5 Invoking certtool</h4>
<a name="index-certtool"></a>


<p>Tool to parse and generate X.509 certificates, requests and private keys.
It can be used interactively or non interactively by
specifying the template command line option.
</p>
<p>The tool accepts files or URLs supported by GnuTLS. In case PIN is required for the URL
access you can provide it using the environment variables GNUTLS_PIN and GNUTLS_SO_PIN.
</p>

<p>This section was generated by <strong>AutoGen</strong>,
using the <code>agtexi-cmd</code> template and the option descriptions for the <code>certtool</code> program.
This software is released under the GNU General Public License, version 3 or later.
</p>

<a name="certtool-usage"></a><a name="certtool-help_002fusage-_0028_002d_002dhelp_0029"></a>
<h4 class="subsubheading">certtool help/usage (<samp>--help</samp>)</h4>
<a name="index-certtool-help"></a>

<p>This is the automatically generated usage text for certtool.
</p>
<p>The text printed is the same whether selected with the <code>help</code> option
(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>).  <code>more-help</code> will print
the usage text by passing it through a pager program.
<code>more-help</code> is disabled on platforms without a working
<code>fork(2)</code> function.  The <code>PAGER</code> environment variable is
used to select the program, defaulting to <samp>more</samp>.  Both will exit
with a status code of 0.
</p>
<div class="example">
<pre class="example">certtool - GnuTLS certificate tool
Usage:  certtool [ -&lt;flag&gt; [&lt;val&gt;] | --&lt;name&gt;[{=| }&lt;val&gt;] ]...

   -d, --debug=num            Enable debugging
                                - it must be in the range:
                                  0 to 9999
   -V, --verbose              More verbose output
                                - may appear multiple times
       --infile=file          Input file
                                - file must pre-exist
       --outfile=str          Output file
   -s, --generate-self-signed  Generate a self-signed certificate
   -c, --generate-certificate  Generate a signed certificate
       --generate-proxy       Generates a proxy certificate
       --generate-crl         Generate a CRL
   -u, --update-certificate   Update a signed certificate
   -p, --generate-privkey     Generate a private key
   -q, --generate-request     Generate a PKCS #10 certificate request
                                - prohibits the option 'infile'
   -e, --verify-chain         Verify a PEM encoded certificate chain
       --verify               Verify a PEM encoded certificate chain using a trusted list
       --verify-crl           Verify a CRL using a trusted list
                                - requires the option 'load-ca-certificate'
       --generate-dh-params   Generate PKCS #3 encoded Diffie-Hellman parameters
       --get-dh-params        Get the included PKCS #3 encoded Diffie-Hellman parameters
       --dh-info              Print information PKCS #3 encoded Diffie-Hellman parameters
       --load-privkey=str     Loads a private key file
       --load-pubkey=str      Loads a public key file
       --load-request=str     Loads a certificate request file
       --load-certificate=str Loads a certificate file
       --load-ca-privkey=str  Loads the certificate authority's private key file
       --load-ca-certificate=str Loads the certificate authority's certificate file
       --password=str         Password to use
       --null-password        Enforce a NULL password
       --empty-password       Enforce an empty password
       --hex-numbers          Print big number in an easier format to parse
       --cprint               In certain operations it prints the information in C-friendly format
   -i, --certificate-info     Print information on the given certificate
       --certificate-pubkey   Print certificate's public key
       --pgp-certificate-info  Print information on the given OpenPGP certificate
       --pgp-ring-info        Print information on the given OpenPGP keyring structure
   -l, --crl-info             Print information on the given CRL structure
       --crq-info             Print information on the given certificate request
       --no-crq-extensions    Do not use extensions in certificate requests
       --p12-info             Print information on a PKCS #12 structure
       --p12-name=str         The PKCS #12 friendly name to use
       --p7-info              Print information on a PKCS #7 structure
       --smime-to-p7          Convert S/MIME to PKCS #7 structure
   -k, --key-info             Print information on a private key
       --pgp-key-info         Print information on an OpenPGP private key
       --pubkey-info          Print information on a public key
       --v1                   Generate an X.509 version 1 certificate (with no extensions)
   -!, --to-p12               Generate a PKCS #12 structure
                                - requires the option 'load-certificate'
   -&quot;, --to-p8                Generate a PKCS #8 structure
   -8, --pkcs8                Use PKCS #8 format for private keys
   -#, --rsa                  Generate RSA key
   -$, --dsa                  Generate DSA key
   -%, --ecc                  Generate ECC (ECDSA) key
   -&amp;, --ecdsa                an alias for the 'ecc' option
   -', --hash=str             Hash algorithm to use for signing
   -(, --inder                Use DER format for input certificates, private keys, and DH parameters
                                - disabled as '--no-inder'
   -), --inraw                an alias for the 'inder' option
   -*, --outder               Use DER format for output certificates, private keys, and DH parameters
                                - disabled as '--no-outder'
   -+, --outraw               an alias for the 'outder' option
   -,, --bits=num             Specify the number of bits for key generate
   --, --curve=str            Specify the curve used for EC key generation
   -., --sec-param=str        Specify the security level [low, legacy, medium, high, ultra]
   -/, --disable-quick-random  No effect
   -0, --template=str         Template file to use for non-interactive operation
   -1, --stdout-info          Print information to stdout instead of stderr
   -2, --ask-pass             Enable interaction for entering password when in batch mode.
   -3, --pkcs-cipher=str      Cipher to use for PKCS #8 and #12 operations
   -4, --provider=str         Specify the PKCS #11 provider library
   -v, --version[=arg]        output version information and exit
   -h, --help                 display extended usage information and exit
   -!, --more-help            extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.

Tool to parse and generate X.509 certificates, requests and private keys.
It can be used interactively or non interactively by specifying the
template command line option.

The tool accepts files or URLs supported by GnuTLS.  In case PIN is
required for the URL access you can provide it using the environment
variables GNUTLS_PIN and GNUTLS_SO_PIN.

</pre></div>

<a name="certtool-debug"></a><a name="debug-option-_0028_002dd_0029-1"></a>
<h4 class="subsubheading">debug option (-d)</h4>

<p>This is the &ldquo;enable debugging&rdquo; option.
This option takes a number argument.
Specifies the debug level.
<a name="certtool-generate_002dcrl"></a></p><a name="generate_002dcrl-option"></a>
<h4 class="subsubheading">generate-crl option</h4>

<p>This is the &ldquo;generate a crl&rdquo; option.
This option generates a CRL. When combined with &ndash;load-crl it would use the loaded CRL as base for the generated (i.e., all revoked certificates in the base will be copied to the new CRL).
<a name="certtool-generate_002drequest"></a></p><a name="generate_002drequest-option-_0028_002dq_0029"></a>
<h4 class="subsubheading">generate-request option (-q)</h4>

<p>This is the &ldquo;generate a pkcs #10 certificate request&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> must not appear in combination with any of the following options:
infile.
</li></ul>

<p>Will generate a PKCS #10 certificate request. To specify a private key use &ndash;load-privkey.
<a name="certtool-verify_002dchain"></a></p><a name="verify_002dchain-option-_0028_002de_0029"></a>
<h4 class="subsubheading">verify-chain option (-e)</h4>

<p>This is the &ldquo;verify a pem encoded certificate chain&rdquo; option.
The last certificate in the chain must be a self signed one. It can be combined with &ndash;verify-purpose or &ndash;verify-hostname.
<a name="certtool-verify"></a></p><a name="verify-option"></a>
<h4 class="subsubheading">verify option</h4>

<p>This is the &ldquo;verify a pem encoded certificate chain using a trusted list&rdquo; option.
The trusted certificate list can be loaded with &ndash;load-ca-certificate. If no
certificate list is provided, then the system&rsquo;s certificate list is used. Note that
during verification multiple paths may be explored. On a successful verification
the successful path will be the last one. It can be combined with &ndash;verify-purpose or &ndash;verify-hostname.
<a name="certtool-verify_002dcrl"></a></p><a name="verify_002dcrl-option"></a>
<h4 class="subsubheading">verify-crl option</h4>

<p>This is the &ldquo;verify a crl using a trusted list&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> must appear in combination with the following options:
load-ca-certificate.
</li></ul>

<p>The trusted certificate list must be loaded with &ndash;load-ca-certificate.
<a name="certtool-verify_002dhostname"></a></p><a name="verify_002dhostname-option"></a>
<h4 class="subsubheading">verify-hostname option</h4>

<p>This is the &ldquo;specify a hostname to be used for certificate chain verification&rdquo; option.
This option takes a string argument.
This is to be combined with one of the verify certificate options.
<a name="certtool-verify_002demail"></a></p><a name="verify_002demail-option"></a>
<h4 class="subsubheading">verify-email option</h4>

<p>This is the &ldquo;specify a email to be used for certificate chain verification&rdquo; option.
This option takes a string argument.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> must not appear in combination with any of the following options:
verify-hostname.
</li></ul>

<p>This is to be combined with one of the verify certificate options.
<a name="certtool-verify_002dpurpose"></a></p><a name="verify_002dpurpose-option"></a>
<h4 class="subsubheading">verify-purpose option</h4>

<p>This is the &ldquo;specify a purpose oid to be used for certificate chain verification&rdquo; option.
This option takes a string argument.
This object identifier restricts the purpose of the certificates to be verified. Example purposes are 1.3.6.1.5.5.7.3.1 (TLS WWW), 1.3.6.1.5.5.7.3.4 (EMAIL) etc. Note that a CA certificate without a purpose set (extended key usage) is valid for any purpose.
<a name="certtool-get_002ddh_002dparams"></a></p><a name="get_002ddh_002dparams-option"></a>
<h4 class="subsubheading">get-dh-params option</h4>

<p>This is the &ldquo;get the included pkcs #3 encoded diffie-hellman parameters&rdquo; option.
Returns stored DH parameters in GnuTLS. Those parameters are used in the SRP protocol. The parameters returned by fresh generation
are more efficient since GnuTLS 3.0.9.
<a name="certtool-load_002dprivkey"></a></p><a name="load_002dprivkey-option"></a>
<h4 class="subsubheading">load-privkey option</h4>

<p>This is the &ldquo;loads a private key file&rdquo; option.
This option takes a string argument.
This can be either a file or a PKCS #11 URL
<a name="certtool-load_002dpubkey"></a></p><a name="load_002dpubkey-option"></a>
<h4 class="subsubheading">load-pubkey option</h4>

<p>This is the &ldquo;loads a public key file&rdquo; option.
This option takes a string argument.
This can be either a file or a PKCS #11 URL
<a name="certtool-load_002dcertificate"></a></p><a name="load_002dcertificate-option"></a>
<h4 class="subsubheading">load-certificate option</h4>

<p>This is the &ldquo;loads a certificate file&rdquo; option.
This option takes a string argument.
This can be either a file or a PKCS #11 URL
<a name="certtool-load_002dca_002dprivkey"></a></p><a name="load_002dca_002dprivkey-option"></a>
<h4 class="subsubheading">load-ca-privkey option</h4>

<p>This is the &ldquo;loads the certificate authority&rsquo;s private key file&rdquo; option.
This option takes a string argument.
This can be either a file or a PKCS #11 URL
<a name="certtool-load_002dca_002dcertificate"></a></p><a name="load_002dca_002dcertificate-option"></a>
<h4 class="subsubheading">load-ca-certificate option</h4>

<p>This is the &ldquo;loads the certificate authority&rsquo;s certificate file&rdquo; option.
This option takes a string argument.
This can be either a file or a PKCS #11 URL
<a name="certtool-password"></a></p><a name="password-option"></a>
<h4 class="subsubheading">password option</h4>

<p>This is the &ldquo;password to use&rdquo; option.
This option takes a string argument.
You can use this option to specify the password in the command line instead of reading it from the tty. Note, that the command line arguments are available for view in others in the system. Specifying password as &rdquo; is the same as specifying no password.
<a name="certtool-null_002dpassword"></a></p><a name="null_002dpassword-option"></a>
<h4 class="subsubheading">null-password option</h4>

<p>This is the &ldquo;enforce a null password&rdquo; option.
This option enforces a NULL password. This is different than the empty or no password in schemas like PKCS #8.
<a name="certtool-empty_002dpassword"></a></p><a name="empty_002dpassword-option"></a>
<h4 class="subsubheading">empty-password option</h4>

<p>This is the &ldquo;enforce an empty password&rdquo; option.
This option enforces an empty password. This is different than the NULL or no password in schemas like PKCS #8.
<a name="certtool-cprint"></a></p><a name="cprint-option"></a>
<h4 class="subsubheading">cprint option</h4>

<p>This is the &ldquo;in certain operations it prints the information in c-friendly format&rdquo; option.
In certain operations it prints the information in C-friendly format, suitable for including into C programs.
<a name="certtool-fingerprint"></a></p><a name="fingerprint-option"></a>
<h4 class="subsubheading">fingerprint option</h4>

<p>This is the &ldquo;print the fingerprint of the given certificate&rdquo; option.
This is a simple hash of the DER encoding of the certificate. It can be combined with the &ndash;hash parameter. However, it is recommended for identification to use the key-id which depends only on the certificate&rsquo;s key.
<a name="certtool-key_002did"></a></p><a name="key_002did-option"></a>
<h4 class="subsubheading">key-id option</h4>

<p>This is the &ldquo;print the key id of the given certificate&rdquo; option.
This is a hash of the public key of the given certificate. It identifies the key uniquely, remains the same on a certificate renewal and depends only on signed fields of the certificate.
<a name="certtool-p12_002dinfo"></a></p><a name="p12_002dinfo-option"></a>
<h4 class="subsubheading">p12-info option</h4>

<p>This is the &ldquo;print information on a pkcs #12 structure&rdquo; option.
This option will dump the contents and print the metadata of the provided PKCS #12 structure.
<a name="certtool-p12_002dname"></a></p><a name="p12_002dname-option"></a>
<h4 class="subsubheading">p12-name option</h4>

<p>This is the &ldquo;the pkcs #12 friendly name to use&rdquo; option.
This option takes a string argument.
The name to be used for the primary certificate and private key in a PKCS #12 file.
<a name="certtool-p7_002dgenerate"></a></p><a name="p7_002dgenerate-option"></a>
<h4 class="subsubheading">p7-generate option</h4>

<p>This is the &ldquo;generate a pkcs #7 structure&rdquo; option.
This option generates a PKCS #7 certificate container structure. To add certificates in the structure use &ndash;load-certificate and &ndash;load-crl.
<a name="certtool-p7_002dsign"></a></p><a name="p7_002dsign-option"></a>
<h4 class="subsubheading">p7-sign option</h4>

<p>This is the &ldquo;signs using a pkcs #7 structure&rdquo; option.
This option generates a PKCS #7 structure containing a signature for the provided data. The data are stored within the structure. The signer certificate has to be specified using &ndash;load-certificate and &ndash;load-privkey.
<a name="certtool-p7_002ddetached_002dsign"></a></p><a name="p7_002ddetached_002dsign-option"></a>
<h4 class="subsubheading">p7-detached-sign option</h4>

<p>This is the &ldquo;signs using a detached pkcs #7 structure&rdquo; option.
This option generates a PKCS #7 structure containing a signature for the provided data. The signer certificate has to be specified using &ndash;load-certificate and &ndash;load-privkey.
<a name="certtool-p7_002dinclude_002dcert"></a></p><a name="p7_002dinclude_002dcert-option"></a>
<h4 class="subsubheading">p7-include-cert option</h4>

<p>This is the &ldquo;the signer&rsquo;s certificate will be included in the cert list.&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-p7-include-cert.
</li><li> It is enabled by default.
</li></ul>

<p>This options works with &ndash;p7-sign or &ndash;p7-detached-sign and will include or exclude the signer&rsquo;s certificate into the generated signature.
<a name="certtool-p7_002dtime"></a></p><a name="p7_002dtime-option"></a>
<h4 class="subsubheading">p7-time option</h4>

<p>This is the &ldquo;will include a timestamp in the pkcs #7 structure&rdquo; option.
This option will include a timestamp in the generated signature
<a name="certtool-p7_002dshow_002ddata"></a></p><a name="p7_002dshow_002ddata-option"></a>
<h4 class="subsubheading">p7-show-data option</h4>

<p>This is the &ldquo;will show the embedded data in the pkcs #7 structure&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-p7-show-data.
</li></ul>

<p>This option can be combined with &ndash;p7-verify and will display the embedded signed data in the PKCS #7 structure.
<a name="certtool-p7_002dverify"></a></p><a name="p7_002dverify-option"></a>
<h4 class="subsubheading">p7-verify option</h4>

<p>This is the &ldquo;verify the provided pkcs #7 structure&rdquo; option.
This option verifies the signed PKCS #7 structure. The certificate list to use for verification can be specified with &ndash;load-ca-certificate. When no certificate list is provided, then the system&rsquo;s certificate list is used. Alternatively a direct signer can be provided using &ndash;load-certificate. A key purpose can be enforced with the &ndash;verify-purpose option, and the &ndash;load-data option will utilize detached data.
<a name="certtool-p8_002dinfo"></a></p><a name="p8_002dinfo-option"></a>
<h4 class="subsubheading">p8-info option</h4>

<p>This is the &ldquo;print information on a pkcs #8 structure&rdquo; option.
This option will print information about encrypted PKCS #8 structures. That option does not require the decryption of the structure.
<a name="certtool-pubkey_002dinfo"></a></p><a name="pubkey_002dinfo-option"></a>
<h4 class="subsubheading">pubkey-info option</h4>

<p>This is the &ldquo;print information on a public key&rdquo; option.
The option combined with &ndash;load-request, &ndash;load-pubkey, &ndash;load-privkey and &ndash;load-certificate will extract the public key of the object in question.
<a name="certtool-to_002dp12"></a></p><a name="to_002dp12-option"></a>
<h4 class="subsubheading">to-p12 option</h4>

<p>This is the &ldquo;generate a pkcs #12 structure&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> must appear in combination with the following options:
load-certificate.
</li></ul>

<p>It requires a certificate, a private key and possibly a CA certificate to be specified.
<a name="certtool-rsa"></a></p><a name="rsa-option"></a>
<h4 class="subsubheading">rsa option</h4>

<p>This is the &ldquo;generate rsa key&rdquo; option.
When combined with &ndash;generate-privkey generates an RSA private key.
<a name="certtool-dsa"></a></p><a name="dsa-option"></a>
<h4 class="subsubheading">dsa option</h4>

<p>This is the &ldquo;generate dsa key&rdquo; option.
When combined with &ndash;generate-privkey generates a DSA private key.
<a name="certtool-ecc"></a></p><a name="ecc-option"></a>
<h4 class="subsubheading">ecc option</h4>

<p>This is the &ldquo;generate ecc (ecdsa) key&rdquo; option.
When combined with &ndash;generate-privkey generates an elliptic curve private key to be used with ECDSA.
<a name="certtool-ecdsa"></a></p><a name="ecdsa-option"></a>
<h4 class="subsubheading">ecdsa option</h4>

<p>This is an alias for the <code>ecc</code> option,
see <a href="#certtool-ecc">the ecc option documentation</a>.
</p>
<a name="certtool-hash"></a><a name="hash-option"></a>
<h4 class="subsubheading">hash option</h4>

<p>This is the &ldquo;hash algorithm to use for signing&rdquo; option.
This option takes a string argument.
Available hash functions are SHA1, RMD160, SHA256, SHA384, SHA512.
<a name="certtool-inder"></a></p><a name="inder-option-1"></a>
<h4 class="subsubheading">inder option</h4>

<p>This is the &ldquo;use der format for input certificates, private keys, and dh parameters &rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-inder.
</li></ul>

<p>The input files will be assumed to be in DER or RAW format. 
Unlike options that in PEM input would allow multiple input data (e.g. multiple 
certificates), when reading in DER format a single data structure is read.
<a name="certtool-inraw"></a></p><a name="inraw-option"></a>
<h4 class="subsubheading">inraw option</h4>

<p>This is an alias for the <code>inder</code> option,
see <a href="#certtool-inder">the inder option documentation</a>.
</p>
<a name="certtool-outder"></a><a name="outder-option-1"></a>
<h4 class="subsubheading">outder option</h4>

<p>This is the &ldquo;use der format for output certificates, private keys, and dh parameters&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-outder.
</li></ul>

<p>The output will be in DER or RAW format.
<a name="certtool-outraw"></a></p><a name="outraw-option"></a>
<h4 class="subsubheading">outraw option</h4>

<p>This is an alias for the <code>outder</code> option,
see <a href="#certtool-outder">the outder option documentation</a>.
</p>
<a name="certtool-curve"></a><a name="curve-option"></a>
<h4 class="subsubheading">curve option</h4>

<p>This is the &ldquo;specify the curve used for ec key generation&rdquo; option.
This option takes a string argument.
Supported values are secp192r1, secp224r1, secp256r1, secp384r1 and secp521r1.
<a name="certtool-sec_002dparam"></a></p><a name="sec_002dparam-option-1"></a>
<h4 class="subsubheading">sec-param option</h4>

<p>This is the &ldquo;specify the security level [low, legacy, medium, high, ultra]&rdquo; option.
This option takes a string argument <samp>Security parameter</samp>.
This is alternative to the bits option.
<a name="certtool-ask_002dpass"></a></p><a name="ask_002dpass-option"></a>
<h4 class="subsubheading">ask-pass option</h4>

<p>This is the &ldquo;enable interaction for entering password when in batch mode.&rdquo; option.
This option will enable interaction to enter password when in batch mode. That is useful when the template option has been specified.
<a name="certtool-pkcs_002dcipher"></a></p><a name="pkcs_002dcipher-option"></a>
<h4 class="subsubheading">pkcs-cipher option</h4>

<p>This is the &ldquo;cipher to use for pkcs #8 and #12 operations&rdquo; option.
This option takes a string argument <samp>Cipher</samp>.
Cipher may be one of 3des, 3des-pkcs12, aes-128, aes-192, aes-256, rc2-40, arcfour.
<a name="certtool-provider"></a></p><a name="provider-option"></a>
<h4 class="subsubheading">provider option</h4>

<p>This is the &ldquo;specify the pkcs #11 provider library&rdquo; option.
This option takes a string argument.
This will override the default options in /etc/gnutls/pkcs11.conf
<a name="certtool-exit-status"></a></p><a name="certtool-exit-status-1"></a>
<h4 class="subsubheading">certtool exit status</h4>

<p>One of the following exit values will be returned:
</p><dl compact="compact">
<dt>&lsquo;<samp>0 (EXIT_SUCCESS)</samp>&rsquo;</dt>
<dd><p>Successful program execution.
</p></dd>
<dt>&lsquo;<samp>1 (EXIT_FAILURE)</samp>&rsquo;</dt>
<dd><p>The operation failed or the command syntax was not valid.
</p></dd>
</dl>
<a name="certtool-See-Also"></a><a name="certtool-See-Also-1"></a>
<h4 class="subsubheading">certtool See Also</h4>
<p>p11tool (1)
<a name="certtool-Examples"></a></p><a name="certtool-Examples-1"></a>
<h4 class="subsubheading">certtool Examples</h4>
<a name="Generating-private-keys"></a>
<h4 class="subsubheading">Generating private keys</h4>
<p>To create an RSA private key, run:
</p><div class="example">
<pre class="example">$ certtool --generate-privkey --outfile key.pem --rsa
</pre></div>

<p>To create a DSA or elliptic curves (ECDSA) private key use the
above command combined with &rsquo;dsa&rsquo; or &rsquo;ecc&rsquo; options.
</p>
<a name="Generating-certificate-requests"></a>
<h4 class="subsubheading">Generating certificate requests</h4>
<p>To create a certificate request (needed when the certificate is  issued  by
another party), run:
</p><div class="example">
<pre class="example">certtool --generate-request --load-privkey key.pem \
   --outfile request.pem
</pre></div>

<p>If the private key is stored in a smart card you can generate
a request by specifying the private key object URL.
</p><div class="example">
<pre class="example">$ ./certtool --generate-request --load-privkey &quot;pkcs11:...&quot; \
  --load-pubkey &quot;pkcs11:...&quot; --outfile request.pem
</pre></div>


<a name="Generating-a-self_002dsigned-certificate"></a>
<h4 class="subsubheading">Generating a self-signed certificate</h4>
<p>To create a self signed certificate, use the command:
</p><div class="example">
<pre class="example">$ certtool --generate-privkey --outfile ca-key.pem
$ certtool --generate-self-signed --load-privkey ca-key.pem \
   --outfile ca-cert.pem
</pre></div>

<p>Note that a self-signed certificate usually belongs to a certificate
authority, that signs other certificates.
</p>
<a name="Generating-a-certificate"></a>
<h4 class="subsubheading">Generating a certificate</h4>
<p>To generate a certificate using the previous request, use the command:
</p><div class="example">
<pre class="example">$ certtool --generate-certificate --load-request request.pem \
   --outfile cert.pem --load-ca-certificate ca-cert.pem \
   --load-ca-privkey ca-key.pem
</pre></div>

<p>To generate a certificate using the private key only, use the command:
</p><div class="example">
<pre class="example">$ certtool --generate-certificate --load-privkey key.pem \
   --outfile cert.pem --load-ca-certificate ca-cert.pem \
   --load-ca-privkey ca-key.pem
</pre></div>

<a name="Certificate-information"></a>
<h4 class="subsubheading">Certificate information</h4>
<p>To view the certificate information, use:
</p><div class="example">
<pre class="example">$ certtool --certificate-info --infile cert.pem
</pre></div>

<a name="PKCS-_002312-structure-generation"></a>
<h4 class="subsubheading">PKCS #12 structure generation</h4>
<p>To generate a PKCS #12 structure using the previous key and certificate,
use the command:
</p><div class="example">
<pre class="example">$ certtool --load-certificate cert.pem --load-privkey key.pem \
   --to-p12 --outder --outfile key.p12
</pre></div>

<p>Some tools (reportedly web browsers) have problems with that file
because it does not contain the CA certificate for the certificate.
To work around that problem in the tool, you can use the
&ndash;load-ca-certificate parameter as follows:
</p>
<div class="example">
<pre class="example">$ certtool --load-ca-certificate ca.pem \
  --load-certificate cert.pem --load-privkey key.pem \
  --to-p12 --outder --outfile key.p12
</pre></div>

<a name="Diffie_002dHellman-parameter-generation"></a>
<h4 class="subsubheading">Diffie-Hellman parameter generation</h4>
<p>To generate parameters for Diffie-Hellman key exchange, use the command:
</p><div class="example">
<pre class="example">$ certtool --generate-dh-params --outfile dh.pem --sec-param medium
</pre></div>

<a name="Proxy-certificate-generation"></a>
<h4 class="subsubheading">Proxy certificate generation</h4>
<p>Proxy certificate can be used to delegate your credential to a
temporary, typically short-lived, certificate.  To create one from the
previously created certificate, first create a temporary key and then
generate a proxy certificate for it, using the commands:
</p>
<div class="example">
<pre class="example">$ certtool --generate-privkey &gt; proxy-key.pem
$ certtool --generate-proxy --load-ca-privkey key.pem \
  --load-privkey proxy-key.pem --load-certificate cert.pem \
  --outfile proxy-cert.pem
</pre></div>

<a name="Certificate-revocation-list-generation"></a>
<h4 class="subsubheading">Certificate revocation list generation</h4>
<p>To create an empty Certificate Revocation List (CRL) do:
</p>
<div class="example">
<pre class="example">$ certtool --generate-crl --load-ca-privkey x509-ca-key.pem \
           --load-ca-certificate x509-ca.pem
</pre></div>

<p>To create a CRL that contains some revoked certificates, place the
certificates in a file and use <code>--load-certificate</code> as follows:
</p>
<div class="example">
<pre class="example">$ certtool --generate-crl --load-ca-privkey x509-ca-key.pem \
  --load-ca-certificate x509-ca.pem --load-certificate revoked-certs.pem
</pre></div>

<p>To verify a Certificate Revocation List (CRL) do:
</p>
<div class="example">
<pre class="example">$ certtool --verify-crl --load-ca-certificate x509-ca.pem &lt; crl.pem
</pre></div>
<a name="certtool-Files"></a><a name="certtool-Files-1"></a>
<h4 class="subsubheading">certtool Files</h4>
<a name="Certtool_0027s-template-file-format"></a>
<h4 class="subsubheading">Certtool&rsquo;s template file format</h4>
<p>A template file can be used to avoid the interactive questions of
certtool. Initially create a file named &rsquo;cert.cfg&rsquo; that contains the information
about the certificate. The template can be used as below:
</p>
<div class="example">
<pre class="example">$ certtool --generate-certificate --load-privkey key.pem  \
   --template cert.cfg --outfile cert.pem \
   --load-ca-certificate ca-cert.pem --load-ca-privkey ca-key.pem
</pre></div>

<p>An example certtool template file that can be used to generate a certificate
request or a self signed certificate follows.
</p>
<div class="example">
<pre class="example"># X.509 Certificate options
#
# DN options

# The organization of the subject.
organization = &quot;Koko inc.&quot;

# The organizational unit of the subject.
unit = &quot;sleeping dept.&quot;

# The locality of the subject.
# locality =

# The state of the certificate owner.
state = &quot;Attiki&quot;

# The country of the subject. Two letter code.
country = GR

# The common name of the certificate owner.
cn = &quot;Cindy Lauper&quot;

# A user id of the certificate owner.
#uid = &quot;clauper&quot;

# Set domain components
#dc = &quot;name&quot;
#dc = &quot;domain&quot;

# If the supported DN OIDs are not adequate you can set
# any OID here.
# For example set the X.520 Title and the X.520 Pseudonym
# by using OID and string pairs.
#dn_oid = 2.5.4.12 Dr. 
#dn_oid = 2.5.4.65 jackal

# This is deprecated and should not be used in new
# certificates.
# pkcs9_email = &quot;none@none.org&quot;

# An alternative way to set the certificate's distinguished name directly
# is with the &quot;dn&quot; option. The attribute names allowed are:
# C (country), street, O (organization), OU (unit), title, CN (common name),
# L (locality), ST (state), placeOfBirth, gender, countryOfCitizenship, 
# countryOfResidence, serialNumber, telephoneNumber, surName, initials, 
# generationQualifier, givenName, pseudonym, dnQualifier, postalCode, name, 
# businessCategory, DC, UID, jurisdictionOfIncorporationLocalityName, 
# jurisdictionOfIncorporationStateOrProvinceName,
# jurisdictionOfIncorporationCountryName, XmppAddr, and numeric OIDs.

#dn = &quot;cn = Nikos,st = New\, Something,C=GR,surName=Mavrogiannopoulos,2.5.4.9=Arkadias&quot;

# The serial number of the certificate
# Comment the field for a time-based serial number.
serial = 007

# In how many days, counting from today, this certificate will expire.
# Use -1 if there is no expiration date.
expiration_days = 700

# Alternatively you may set concrete dates and time. The GNU date string 
# formats are accepted. See:
# http://www.gnu.org/software/tar/manual/html_node/Date-input-formats.html

#activation_date = &quot;2004-02-29 16:21:42&quot;
#expiration_date = &quot;2025-02-29 16:24:41&quot;

# X.509 v3 extensions

# A dnsname in case of a WWW server.
#dns_name = &quot;www.none.org&quot;
#dns_name = &quot;www.morethanone.org&quot;

# A subject alternative name URI
#uri = &quot;http://www.example.com&quot;

# An IP address in case of a server.
#ip_address = &quot;192.168.1.1&quot;

# An email in case of a person
email = &quot;none@none.org&quot;

# Challenge password used in certificate requests
challenge_password = 123456

# Password when encrypting a private key
#password = secret

# An URL that has CRLs (certificate revocation lists)
# available. Needed in CA certificates.
#crl_dist_points = &quot;http://www.getcrl.crl/getcrl/&quot;

# Whether this is a CA certificate or not
#ca

# Subject Unique ID (in hex)
#subject_unique_id = 00153224

# Issuer Unique ID (in hex)
#issuer_unique_id = 00153225

#### Key usage

# The following key usage flags are used by CAs and end certificates

# Whether this certificate will be used to sign data (needed
# in TLS DHE ciphersuites). This is the digitalSignature flag
# in RFC5280 terminology.
signing_key

# Whether this certificate will be used to encrypt data (needed
# in TLS RSA ciphersuites). Note that it is preferred to use different
# keys for encryption and signing. This is the keyEncipherment flag
# in RFC5280 terminology.
encryption_key

# Whether this key will be used to sign other certificates. The
# keyCertSign flag in RFC5280 terminology.
#cert_signing_key

# Whether this key will be used to sign CRLs. The
# cRLSign flag in RFC5280 terminology.
#crl_signing_key

# The keyAgreement flag of RFC5280. It's purpose is loosely
# defined. Not use it unless required by a protocol.
#key_agreement

# The dataEncipherment flag of RFC5280. It's purpose is loosely
# defined. Not use it unless required by a protocol.
#data_encipherment

# The nonRepudiation flag of RFC5280. It's purpose is loosely
# defined. Not use it unless required by a protocol.
#non_repudiation

#### Extended key usage (key purposes)

# The following extensions are used in an end certificate
# to clarify its purpose. Some CAs also use it to indicate
# the types of certificates they are purposed to sign.


# Whether this certificate will be used for a TLS client;
# this sets the id-kp-serverAuth (1.3.6.1.5.5.7.3.1) of 
# extended key usage.
#tls_www_client

# Whether this certificate will be used for a TLS server;
# This sets the id-kp-clientAuth (1.3.6.1.5.5.7.3.2) of 
# extended key usage.
#tls_www_server

# Whether this key will be used to sign code. This sets the
# id-kp-codeSigning (1.3.6.1.5.5.7.3.3) of extended key usage
# extension.
#code_signing_key

# Whether this key will be used to sign OCSP data. This sets the
# id-kp-OCSPSigning (1.3.6.1.5.5.7.3.9) of extended key usage extension.
#ocsp_signing_key

# Whether this key will be used for time stamping. This sets the
# id-kp-timeStamping (1.3.6.1.5.5.7.3.8) of extended key usage extension.
#time_stamping_key

# Whether this key will be used for email protection. This sets the
# id-kp-emailProtection (1.3.6.1.5.5.7.3.4) of extended key usage extension.
#email_protection_key

# Whether this key will be used for IPsec IKE operations (1.3.6.1.5.5.7.3.17).
#ipsec_ike_key

## adding custom key purpose OIDs

# for microsoft smart card logon
# key_purpose_oid = 1.3.6.1.4.1.311.20.2.2

# for email protection
# key_purpose_oid = 1.3.6.1.5.5.7.3.4

# for any purpose (must not be used in intermediate CA certificates)
# key_purpose_oid = 2.5.29.37.0

### end of key purpose OIDs

# When generating a certificate from a certificate
# request, then honor the extensions stored in the request
# and store them in the real certificate.
#honor_crq_extensions

# Path length contraint. Sets the maximum number of
# certificates that can be used to certify this certificate.
# (i.e. the certificate chain length)
#path_len = -1
#path_len = 2

# OCSP URI
# ocsp_uri = http://my.ocsp.server/ocsp

# CA issuers URI
# ca_issuers_uri = http://my.ca.issuer

# Certificate policies
#policy1 = 1.3.6.1.4.1.5484.1.10.99.1.0
#policy1_txt = &quot;This is a long policy to summarize&quot;
#policy1_url = http://www.example.com/a-policy-to-read

#policy2 = 1.3.6.1.4.1.5484.1.10.99.1.1
#policy2_txt = &quot;This is a short policy&quot;
#policy2_url = http://www.example.com/another-policy-to-read

# Name constraints

# DNS
#nc_permit_dns = example.com
#nc_exclude_dns = test.example.com

# EMAIL
#nc_permit_email = &quot;nmav@ex.net&quot;

# Exclude subdomains of example.com
#nc_exclude_email = .example.com

# Exclude all e-mail addresses of example.com
#nc_exclude_email = example.com


# Options for proxy certificates
#proxy_policy_language = 1.3.6.1.5.5.7.21.1


# Options for generating a CRL

# The number of days the next CRL update will be due.
# next CRL update will be in 43 days
#crl_next_update = 43

# this is the 5th CRL by this CA
# Comment the field for a time-based number.
#crl_number = 5

# Specify the update dates more precisely.
#crl_this_update_date = &quot;2004-02-29 16:21:42&quot;
#crl_next_update_date = &quot;2025-02-29 16:24:41&quot;

# The date that the certificates will be made seen as
# being revoked.
#crl_revocation_date = &quot;2025-02-29 16:24:41&quot;

</pre></div>

<hr>
<a name="ocsptool-Invocation"></a>
<div class="header">
<p>
Next: <a href="#danetool-Invocation" accesskey="n" rel="next">danetool Invocation</a>, Previous: <a href="#certtool-Invocation" accesskey="p" rel="prev">certtool Invocation</a>, Up: <a href="#More-on-certificate-authentication" accesskey="u" rel="up">More on certificate authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Invoking-ocsptool"></a>
<h4 class="subsection">4.2.6 Invoking ocsptool</h4>
<a name="index-ocsptool"></a>


<p>Ocsptool is a program that can parse and print information about
OCSP requests/responses, generate requests and verify responses.
</p>

<p>This section was generated by <strong>AutoGen</strong>,
using the <code>agtexi-cmd</code> template and the option descriptions for the <code>ocsptool</code> program.
This software is released under the GNU General Public License, version 3 or later.
</p>

<a name="ocsptool-usage"></a><a name="ocsptool-help_002fusage-_0028_002d_002dhelp_0029"></a>
<h4 class="subsubheading">ocsptool help/usage (<samp>--help</samp>)</h4>
<a name="index-ocsptool-help"></a>

<p>This is the automatically generated usage text for ocsptool.
</p>
<p>The text printed is the same whether selected with the <code>help</code> option
(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>).  <code>more-help</code> will print
the usage text by passing it through a pager program.
<code>more-help</code> is disabled on platforms without a working
<code>fork(2)</code> function.  The <code>PAGER</code> environment variable is
used to select the program, defaulting to <samp>more</samp>.  Both will exit
with a status code of 0.
</p>
<div class="example">
<pre class="example">ocsptool - GnuTLS OCSP tool
Usage:  ocsptool [ -&lt;flag&gt; [&lt;val&gt;] | --&lt;name&gt;[{=| }&lt;val&gt;] ]...

   -d, --debug=num            Enable debugging
                                - it must be in the range:
                                  0 to 9999
   -V, --verbose              More verbose output
                                - may appear multiple times
       --infile=file          Input file
                                - file must pre-exist
       --outfile=str          Output file
       --ask[=arg]            Ask an OCSP/HTTP server on a certificate validity
                                - requires these options:
                                load-cert
                                load-issuer
   -e, --verify-response      Verify response
   -i, --request-info         Print information on a OCSP request
   -j, --response-info        Print information on a OCSP response
   -q, --generate-request     Generate an OCSP request
       --nonce                Use (or not) a nonce to OCSP request
                                - disabled as '--no-nonce'
       --load-issuer=file     Read issuer certificate from file
                                - file must pre-exist
       --load-cert=file       Read certificate to check from file
                                - file must pre-exist
       --load-trust=file      Read OCSP trust anchors from file
                                - prohibits the option 'load-signer'
                                - file must pre-exist
       --load-signer=file     Read OCSP response signer from file
                                - prohibits the option 'load-trust'
                                - file must pre-exist
       --inder                Use DER format for input certificates and private keys
                                - disabled as '--no-inder'
   -Q, --load-request=file    Read DER encoded OCSP request from file
                                - file must pre-exist
   -S, --load-response=file   Read DER encoded OCSP response from file
                                - file must pre-exist
   -v, --version[=arg]        output version information and exit
   -h, --help                 display extended usage information and exit
   -!, --more-help            extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.

Ocsptool is a program that can parse and print information about OCSP
requests/responses, generate requests and verify responses.

</pre></div>

<a name="ocsptool-debug"></a><a name="debug-option-_0028_002dd_0029-2"></a>
<h4 class="subsubheading">debug option (-d)</h4>

<p>This is the &ldquo;enable debugging&rdquo; option.
This option takes a number argument.
Specifies the debug level.
<a name="ocsptool-ask"></a></p><a name="ask-option"></a>
<h4 class="subsubheading">ask option</h4>

<p>This is the &ldquo;ask an ocsp/http server on a certificate validity&rdquo; option.
This option takes an optional string argument <samp>server name|url</samp>.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> must appear in combination with the following options:
load-cert, load-issuer.
</li></ul>

<p>Connects to the specified HTTP OCSP server and queries on the validity of the loaded certificate.
<a name="ocsptool-exit-status"></a></p><a name="ocsptool-exit-status-1"></a>
<h4 class="subsubheading">ocsptool exit status</h4>

<p>One of the following exit values will be returned:
</p><dl compact="compact">
<dt>&lsquo;<samp>0 (EXIT_SUCCESS)</samp>&rsquo;</dt>
<dd><p>Successful program execution.
</p></dd>
<dt>&lsquo;<samp>1 (EXIT_FAILURE)</samp>&rsquo;</dt>
<dd><p>The operation failed or the command syntax was not valid.
</p></dd>
</dl>
<a name="ocsptool-See-Also"></a><a name="ocsptool-See-Also-1"></a>
<h4 class="subsubheading">ocsptool See Also</h4>
<p>certtool (1)
<a name="ocsptool-Examples"></a></p><a name="ocsptool-Examples-1"></a>
<h4 class="subsubheading">ocsptool Examples</h4>
<a name="Print-information-about-an-OCSP-request"></a>
<h4 class="subsubheading">Print information about an OCSP request</h4>

<p>To parse an OCSP request and print information about the content, the
<code>-i</code> or <code>--request-info</code> parameter may be used as follows.
The <code>-Q</code> parameter specify the name of the file containing the
OCSP request, and it should contain the OCSP request in binary DER
format.
</p>
<div class="example">
<pre class="example">$ ocsptool -i -Q ocsp-request.der
</pre></div>

<p>The input file may also be sent to standard input like this:
</p>
<div class="example">
<pre class="example">$ cat ocsp-request.der | ocsptool --request-info
</pre></div>

<a name="Print-information-about-an-OCSP-response"></a>
<h4 class="subsubheading">Print information about an OCSP response</h4>

<p>Similar to parsing OCSP requests, OCSP responses can be parsed using
the <code>-j</code> or <code>--response-info</code> as follows.
</p>
<div class="example">
<pre class="example">$ ocsptool -j -Q ocsp-response.der
$ cat ocsp-response.der | ocsptool --response-info
</pre></div>

<a name="Generate-an-OCSP-request"></a>
<h4 class="subsubheading">Generate an OCSP request</h4>

<p>The <code>-q</code> or <code>--generate-request</code> parameters are used to
generate an OCSP request.  By default the OCSP request is written to
standard output in binary DER format, but can be stored in a file
using <code>--outfile</code>.  To generate an OCSP request the issuer of the
certificate to check needs to be specified with <code>--load-issuer</code>
and the certificate to check with <code>--load-cert</code>.  By default PEM
format is used for these files, although <code>--inder</code> can be used to
specify that the input files are in DER format.
</p>
<div class="example">
<pre class="example">$ ocsptool -q --load-issuer issuer.pem --load-cert client.pem \
           --outfile ocsp-request.der
</pre></div>

<p>When generating OCSP requests, the tool will add an OCSP extension
containing a nonce.  This behaviour can be disabled by specifying
<code>--no-nonce</code>.
</p>
<a name="Verify-signature-in-OCSP-response"></a>
<h4 class="subsubheading">Verify signature in OCSP response</h4>

<p>To verify the signature in an OCSP response the <code>-e</code> or
<code>--verify-response</code> parameter is used.  The tool will read an
OCSP response in DER format from standard input, or from the file
specified by <code>--load-response</code>.  The OCSP response is verified
against a set of trust anchors, which are specified using
<code>--load-trust</code>.  The trust anchors are concatenated certificates
in PEM format.  The certificate that signed the OCSP response needs to
be in the set of trust anchors, or the issuer of the signer
certificate needs to be in the set of trust anchors and the OCSP
Extended Key Usage bit has to be asserted in the signer certificate.
</p>
<div class="example">
<pre class="example">$ ocsptool -e --load-trust issuer.pem \
           --load-response ocsp-response.der
</pre></div>

<p>The tool will print status of verification.
</p>
<a name="Verify-signature-in-OCSP-response-against-given-certificate"></a>
<h4 class="subsubheading">Verify signature in OCSP response against given certificate</h4>

<p>It is possible to override the normal trust logic if you know that a
certain certificate is supposed to have signed the OCSP response, and
you want to use it to check the signature.  This is achieved using
<code>--load-signer</code> instead of <code>--load-trust</code>.  This will load
one certificate and it will be used to verify the signature in the
OCSP response.  It will not check the Extended Key Usage bit.
</p>
<div class="example">
<pre class="example">$ ocsptool -e --load-signer ocsp-signer.pem \
           --load-response ocsp-response.der
</pre></div>

<p>This approach is normally only relevant in two situations.  The first
is when the OCSP response does not contain a copy of the signer
certificate, so the <code>--load-trust</code> code would fail.  The second
is if you want to avoid the indirect mode where the OCSP response
signer certificate is signed by a trust anchor.
</p>
<a name="Real_002dworld-example"></a>
<h4 class="subsubheading">Real-world example</h4>

<p>Here is an example of how to generate an OCSP request for a
certificate and to verify the response.  For illustration we&rsquo;ll use
the <code>blog.josefsson.org</code> host, which (as of writing) uses a
certificate from CACert.  First we&rsquo;ll use <code>gnutls-cli</code> to get a
copy of the server certificate chain.  The server is not required to
send this information, but this particular one is configured to do so.
</p>
<div class="example">
<pre class="example">$ echo | gnutls-cli -p 443 blog.josefsson.org --print-cert &gt; chain.pem
</pre></div>

<p>Use a text editor on <code>chain.pem</code> to create three files for each
separate certificates, called <code>cert.pem</code> for the first
certificate for the domain itself, secondly <code>issuer.pem</code> for the
intermediate certificate and <code>root.pem</code> for the final root
certificate.
</p>
<p>The domain certificate normally contains a pointer to where the OCSP
responder is located, in the Authority Information Access Information
extension.  For example, from <code>certtool -i &lt; cert.pem</code> there is
this information:
</p>
<div class="example">
<pre class="example">Authority Information Access Information (not critical):
Access Method: 1.3.6.1.5.5.7.48.1 (id-ad-ocsp)
Access Location URI: http://ocsp.CAcert.org/
</pre></div>

<p>This means the CA support OCSP queries over HTTP.  We are now ready to
create a OCSP request for the certificate.
</p>
<div class="example">
<pre class="example">$ ocsptool --ask ocsp.CAcert.org --load-issuer issuer.pem \
           --load-cert cert.pem --outfile ocsp-response.der
</pre></div>

<p>The request is sent via HTTP to the OCSP server address specified. If the
address is ommited ocsptool will use the address stored in the certificate.
</p>
<hr>
<a name="danetool-Invocation"></a>
<div class="header">
<p>
Previous: <a href="#ocsptool-Invocation" accesskey="p" rel="prev">ocsptool Invocation</a>, Up: <a href="#More-on-certificate-authentication" accesskey="u" rel="up">More on certificate authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Invoking-danetool"></a>
<h4 class="subsection">4.2.7 Invoking danetool</h4>
<a name="index-danetool"></a>


<p>Tool to generate and check DNS resource records for the DANE protocol.
</p>
<p>This section was generated by <strong>AutoGen</strong>,
using the <code>agtexi-cmd</code> template and the option descriptions for the <code>danetool</code> program.
This software is released under the GNU General Public License, version 3 or later.
</p>

<a name="danetool-usage"></a><a name="danetool-help_002fusage-_0028_002d_002dhelp_0029"></a>
<h4 class="subsubheading">danetool help/usage (<samp>--help</samp>)</h4>
<a name="index-danetool-help"></a>

<p>This is the automatically generated usage text for danetool.
</p>
<p>The text printed is the same whether selected with the <code>help</code> option
(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>).  <code>more-help</code> will print
the usage text by passing it through a pager program.
<code>more-help</code> is disabled on platforms without a working
<code>fork(2)</code> function.  The <code>PAGER</code> environment variable is
used to select the program, defaulting to <samp>more</samp>.  Both will exit
with a status code of 0.
</p>
<div class="example">
<pre class="example">danetool - GnuTLS DANE tool
Usage:  danetool [ -&lt;flag&gt; [&lt;val&gt;] | --&lt;name&gt;[{=| }&lt;val&gt;] ]...

   -d, --debug=num            Enable debugging
                                - it must be in the range:
                                  0 to 9999
   -V, --verbose              More verbose output
                                - may appear multiple times
       --infile=file          Input file
                                - file must pre-exist
       --outfile=str          Output file
       --load-pubkey=str      Loads a public key file
       --load-certificate=str Loads a certificate file
       --dlv=str              Sets a DLV file
       --hash=str             Hash algorithm to use for signing
       --check=str            Check a host's DANE TLSA entry
       --check-ee             Check only the end-entity's certificate
       --check-ca             Check only the CA's certificate
       --tlsa-rr              Print the DANE RR data on a certificate or public key
                                - requires the option 'host'
       --host=str             Specify the hostname to be used in the DANE RR
       --proto=str            The protocol set for DANE data (tcp, udp etc.)
       --port=num             Specify the port number for the DANE data
       --app-proto=str        an alias for the 'starttls-proto' option
       --starttls-proto=str   The application protocol to be used to obtain the server's certificate
(https, ftp, smtp, imap, ldap, xmpp)
       --ca                   Whether the provided certificate or public key is a Certificate
Authority
       --x509                 Use the hash of the X.509 certificate, rather than the public key
       --local                an alias for the 'domain' option
                                - enabled by default
       --domain               The provided certificate or public key is issued by the local domain
                                - disabled as '--no-domain'
                                - enabled by default
       --local-dns            Use the local DNS server for DNSSEC resolving
                                - disabled as '--no-local-dns'
       --insecure             Do not verify any DNSSEC signature
       --inder                Use DER format for input certificates and private keys
                                - disabled as '--no-inder'
       --inraw                an alias for the 'inder' option
       --print-raw            Print the received DANE data in raw format
                                - disabled as '--no-print-raw'
       --quiet                Suppress several informational messages
   -v, --version[=arg]        output version information and exit
   -h, --help                 display extended usage information and exit
   -!, --more-help            extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.

Tool to generate and check DNS resource records for the DANE protocol.

</pre></div>

<a name="danetool-debug"></a><a name="debug-option-_0028_002dd_0029-3"></a>
<h4 class="subsubheading">debug option (-d)</h4>

<p>This is the &ldquo;enable debugging&rdquo; option.
This option takes a number argument.
Specifies the debug level.
<a name="danetool-load_002dpubkey"></a></p><a name="load_002dpubkey-option-1"></a>
<h4 class="subsubheading">load-pubkey option</h4>

<p>This is the &ldquo;loads a public key file&rdquo; option.
This option takes a string argument.
This can be either a file or a PKCS #11 URL
<a name="danetool-load_002dcertificate"></a></p><a name="load_002dcertificate-option-1"></a>
<h4 class="subsubheading">load-certificate option</h4>

<p>This is the &ldquo;loads a certificate file&rdquo; option.
This option takes a string argument.
This can be either a file or a PKCS #11 URL
<a name="danetool-dlv"></a></p><a name="dlv-option"></a>
<h4 class="subsubheading">dlv option</h4>

<p>This is the &ldquo;sets a dlv file&rdquo; option.
This option takes a string argument.
This sets a DLV file to be used for DNSSEC verification.
<a name="danetool-hash"></a></p><a name="hash-option-1"></a>
<h4 class="subsubheading">hash option</h4>

<p>This is the &ldquo;hash algorithm to use for signing&rdquo; option.
This option takes a string argument.
Available hash functions are SHA1, RMD160, SHA256, SHA384, SHA512.
<a name="danetool-check"></a></p><a name="check-option"></a>
<h4 class="subsubheading">check option</h4>

<p>This is the &ldquo;check a host&rsquo;s dane tlsa entry&rdquo; option.
This option takes a string argument.
Obtains the DANE TLSA entry from the given hostname and prints information. Note that the actual certificate of the host can be provided using &ndash;load-certificate, otherwise danetool will connect to the server to obtain it. The exit code on verification success will be zero.
<a name="danetool-check_002dee"></a></p><a name="check_002dee-option"></a>
<h4 class="subsubheading">check-ee option</h4>

<p>This is the &ldquo;check only the end-entity&rsquo;s certificate&rdquo; option.
Checks the end-entity&rsquo;s certificate only. Trust anchors or CAs are not considered.
<a name="danetool-check_002dca"></a></p><a name="check_002dca-option"></a>
<h4 class="subsubheading">check-ca option</h4>

<p>This is the &ldquo;check only the ca&rsquo;s certificate&rdquo; option.
Checks the trust anchor&rsquo;s and CA&rsquo;s certificate only. End-entities are not considered.
<a name="danetool-tlsa_002drr"></a></p><a name="tlsa_002drr-option"></a>
<h4 class="subsubheading">tlsa-rr option</h4>

<p>This is the &ldquo;print the dane rr data on a certificate or public key&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> must appear in combination with the following options:
host.
</li></ul>

<p>This command prints the DANE RR data needed to enable DANE on a DNS server.
<a name="danetool-host"></a></p><a name="host-option"></a>
<h4 class="subsubheading">host option</h4>

<p>This is the &ldquo;specify the hostname to be used in the dane rr&rdquo; option.
This option takes a string argument <samp>Hostname</samp>.
This command sets the hostname for the DANE RR.
<a name="danetool-proto"></a></p><a name="proto-option"></a>
<h4 class="subsubheading">proto option</h4>

<p>This is the &ldquo;the protocol set for dane data (tcp, udp etc.)&rdquo; option.
This option takes a string argument <samp>Protocol</samp>.
This command specifies the protocol for the service set in the DANE data.
<a name="danetool-app_002dproto"></a></p><a name="app_002dproto-option"></a>
<h4 class="subsubheading">app-proto option</h4>

<p>This is an alias for the <code>starttls-proto</code> option,
see <a href="#danetool-starttls_002dproto">the starttls-proto option documentation</a>.
</p>
<a name="danetool-starttls_002dproto"></a><a name="starttls_002dproto-option"></a>
<h4 class="subsubheading">starttls-proto option</h4>

<p>This is the &ldquo;the application protocol to be used to obtain the server&rsquo;s certificate (https, ftp, smtp, imap, ldap, xmpp)&rdquo; option.
This option takes a string argument.
When the server&rsquo;s certificate isn&rsquo;t provided danetool will connect to the server to obtain the certificate. In that case it is required to known the protocol to talk with the server prior to initiating the TLS handshake.
<a name="danetool-ca"></a></p><a name="ca-option"></a>
<h4 class="subsubheading">ca option</h4>

<p>This is the &ldquo;whether the provided certificate or public key is a certificate authority&rdquo; option.
Marks the DANE RR as a CA certificate if specified.
<a name="danetool-x509"></a></p><a name="x509-option"></a>
<h4 class="subsubheading">x509 option</h4>

<p>This is the &ldquo;use the hash of the x.509 certificate, rather than the public key&rdquo; option.
This option forces the generated record to contain the hash of the full X.509 certificate. By default only the hash of the public key is used.
<a name="danetool-local"></a></p><a name="local-option"></a>
<h4 class="subsubheading">local option</h4>

<p>This is an alias for the <code>domain</code> option,
see <a href="#danetool-domain">the domain option documentation</a>.
</p>
<a name="danetool-domain"></a><a name="domain-option"></a>
<h4 class="subsubheading">domain option</h4>

<p>This is the &ldquo;the provided certificate or public key is issued by the local domain&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-domain.
</li><li> It is enabled by default.
</li></ul>

<p>DANE distinguishes certificates and public keys offered via the DNSSEC to trusted and local entities. This flag indicates that this is a domain-issued certificate, meaning that there could be no CA involved.
<a name="danetool-local_002ddns"></a></p><a name="local_002ddns-option"></a>
<h4 class="subsubheading">local-dns option</h4>

<p>This is the &ldquo;use the local dns server for dnssec resolving&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-local-dns.
</li></ul>

<p>This option will use the local DNS server for DNSSEC.
This is disabled by default due to many servers not allowing DNSSEC.
<a name="danetool-insecure"></a></p><a name="insecure-option"></a>
<h4 class="subsubheading">insecure option</h4>

<p>This is the &ldquo;do not verify any dnssec signature&rdquo; option.
Ignores any DNSSEC signature verification results.
<a name="danetool-inder"></a></p><a name="inder-option-2"></a>
<h4 class="subsubheading">inder option</h4>

<p>This is the &ldquo;use der format for input certificates and private keys&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-inder.
</li></ul>

<p>The input files will be assumed to be in DER or RAW format. 
Unlike options that in PEM input would allow multiple input data (e.g. multiple 
certificates), when reading in DER format a single data structure is read.
<a name="danetool-inraw"></a></p><a name="inraw-option-1"></a>
<h4 class="subsubheading">inraw option</h4>

<p>This is an alias for the <code>inder</code> option,
see <a href="#danetool-inder">the inder option documentation</a>.
</p>
<a name="danetool-print_002draw"></a><a name="print_002draw-option"></a>
<h4 class="subsubheading">print-raw option</h4>

<p>This is the &ldquo;print the received dane data in raw format&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-print-raw.
</li></ul>

<p>This option will print the received DANE data.
<a name="danetool-quiet"></a></p><a name="quiet-option"></a>
<h4 class="subsubheading">quiet option</h4>

<p>This is the &ldquo;suppress several informational messages&rdquo; option.
In that case on the exit code can be used as an indication of verification success
<a name="danetool-exit-status"></a></p><a name="danetool-exit-status-1"></a>
<h4 class="subsubheading">danetool exit status</h4>

<p>One of the following exit values will be returned:
</p><dl compact="compact">
<dt>&lsquo;<samp>0 (EXIT_SUCCESS)</samp>&rsquo;</dt>
<dd><p>Successful program execution.
</p></dd>
<dt>&lsquo;<samp>1 (EXIT_FAILURE)</samp>&rsquo;</dt>
<dd><p>The operation failed or the command syntax was not valid.
</p></dd>
</dl>
<a name="danetool-See-Also"></a><a name="danetool-See-Also-1"></a>
<h4 class="subsubheading">danetool See Also</h4>
<p>certtool (1)
<a name="danetool-Examples"></a></p><a name="danetool-Examples-1"></a>
<h4 class="subsubheading">danetool Examples</h4>
<a name="DANE-TLSA-RR-generation"></a>
<h4 class="subsubheading">DANE TLSA RR generation</h4>

<p>To create a DANE TLSA resource record for a certificate (or public key) 
that was issued localy and may or may not be signed by a CA use the following command.
</p><div class="example">
<pre class="example">$ danetool --tlsa-rr --host www.example.com --load-certificate cert.pem
</pre></div>

<p>To create a DANE TLSA resource record for a CA signed certificate, which will
be marked as such use the following command.
</p><div class="example">
<pre class="example">$ danetool --tlsa-rr --host www.example.com --load-certificate cert.pem \
  --no-domain
</pre></div>

<p>The former is useful to add in your DNS entry even if your certificate is signed 
by a CA. That way even users who do not trust your CA will be able to verify your
certificate using DANE.
</p>
<p>In order to create a record for the CA signer of your certificate use the following.
</p><div class="example">
<pre class="example">$ danetool --tlsa-rr --host www.example.com --load-certificate cert.pem \
  --ca --no-domain
</pre></div>

<p>To read a server&rsquo;s DANE TLSA entry, use:
</p><div class="example">
<pre class="example">$ danetool --check www.example.com --proto tcp --port 443
</pre></div>

<p>To verify a server&rsquo;s DANE TLSA entry, use:
</p><div class="example">
<pre class="example">$ danetool --check www.example.com --proto tcp --port 443 --load-certificate chain.pem
</pre></div>

<hr>
<a name="Shared_002dkey-and-anonymous-authentication"></a>
<div class="header">
<p>
Next: <a href="#Selecting-an-appropriate-authentication-method" accesskey="n" rel="next">Selecting an appropriate authentication method</a>, Previous: <a href="#More-on-certificate-authentication" accesskey="p" rel="prev">More on certificate authentication</a>, Up: <a href="#Authentication-methods" accesskey="u" rel="up">Authentication methods</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Shared_002dkey-and-anonymous-authentication-1"></a>
<h3 class="section">4.3 Shared-key and anonymous authentication</h3>

<p>In addition to certificate authentication, the TLS protocol may be
used with password, shared-key and anonymous authentication methods.
The rest of this chapter discusses details of these methods.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#SRP-authentication" accesskey="1">SRP authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#PSK-authentication" accesskey="2">PSK authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Anonymous-authentication" accesskey="3">Anonymous authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="SRP-authentication"></a>
<div class="header">
<p>
Next: <a href="#PSK-authentication" accesskey="n" rel="next">PSK authentication</a>, Up: <a href="#Shared_002dkey-and-anonymous-authentication" accesskey="u" rel="up">Shared-key and anonymous authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="SRP-authentication-1"></a>
<h4 class="subsection">4.3.1 SRP authentication</h4>

<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Authentication-using-SRP" accesskey="1">Authentication using SRP</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#srptool-Invocation" accesskey="2">srptool Invocation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Invoking srptool
</td></tr>
</table>

<hr>
<a name="Authentication-using-SRP"></a>
<div class="header">
<p>
Next: <a href="#srptool-Invocation" accesskey="n" rel="next">srptool Invocation</a>, Up: <a href="#SRP-authentication" accesskey="u" rel="up">SRP authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Authentication-using-SRP-1"></a>
<h4 class="subsubsection">4.3.1.1 Authentication using <acronym>SRP</acronym></h4>
<a name="index-SRP-authentication"></a>

<p><acronym>GnuTLS</acronym> supports authentication via the Secure Remote Password 
or <acronym>SRP</acronym> protocol (see [<em>RFC2945,TOMSRP</em>] for a description).
The <acronym>SRP</acronym> key exchange is an extension to the
<acronym>TLS</acronym> protocol, and it provides an authenticated with a 
password key exchange. The peers can be identified using a single password, 
or there can be combinations where the client is authenticated using <acronym>SRP</acronym>
and the server using a certificate.
</p>
<p>The advantage of <acronym>SRP</acronym> authentication, over other proposed
secure password authentication schemes, is that <acronym>SRP</acronym> is not
susceptible to off-line dictionary attacks.
Moreover, SRP does not require the server to hold the user&rsquo;s password.
This kind of protection is similar to the one used traditionally in the <acronym>UNIX</acronym>
<samp>/etc/passwd</samp> file, where the contents of this file did not cause
harm to the system security if they were revealed.  The <acronym>SRP</acronym>
needs instead of the plain password something called a verifier, which
is calculated using the user&rsquo;s password, and if stolen cannot be used
to impersonate the user. 
</p>
<p>Typical conventions in SRP are a password file, called <samp>tpasswd</samp> that 
holds the SRP verifiers (encoded passwords) and another file, <samp>tpasswd.conf</samp>,
which holds the allowed SRP parameters.  The included in GnuTLS helper 
follow those conventions. The srptool program, discussed in the next section
is a tool to manipulate the SRP parameters.
</p>
<p>The implementation in <acronym>GnuTLS</acronym> is based on [<em>TLSSRP</em>]. The
supported key exchange methods are shown below.
</p>
<dl compact="compact">
<dt><code>SRP:</code></dt>
<dd><p>Authentication using the <acronym>SRP</acronym> protocol.
</p>
</dd>
<dt><code>SRP_DSS:</code></dt>
<dd><p>Client authentication using the <acronym>SRP</acronym> protocol. Server is
authenticated using a certificate with DSA parameters.
</p>
</dd>
<dt><code>SRP_RSA:</code></dt>
<dd><p>Client authentication using the <acronym>SRP</acronym> protocol. Server is
authenticated using a certificate with RSA parameters.
</p>
</dd>
</dl>






<dl>
<dt><a name="index-gnutls_005fsrp_005fverifier"></a>Function: <em>int</em> <strong>gnutls_srp_verifier</strong> <em>(const char * <var>username</var>, const char * <var>password</var>, const gnutls_datum_t * <var>salt</var>, const gnutls_datum_t * <var>generator</var>, const gnutls_datum_t * <var>prime</var>, gnutls_datum_t * <var>res</var>)</em></dt>
<dd><p><var>username</var>: is the user&rsquo;s name
</p>
<p><var>password</var>: is the user&rsquo;s password
</p>
<p><var>salt</var>: should be some randomly generated bytes
</p>
<p><var>generator</var>: is the generator of the group
</p>
<p><var>prime</var>: is the group&rsquo;s prime
</p>
<p><var>res</var>: where the verifier will be stored.
</p>
<p>This function will create an SRP verifier, as specified in
RFC2945.  The  <code>prime</code> and  <code>generator</code> should be one of the static
parameters defined in gnutls/gnutls.h or may be generated.
</p>
<p>The verifier will be allocated with  <code>gnutls_malloc</code> () and will be stored in
 <code>res</code> using binary format.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p></dd></dl>

<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fsrp_005fbase64_005fencode2">gnutls_srp_base64_encode2</a> (const gnutls_datum_t * <var>data</var>, gnutls_datum_t * <var>result</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fsrp_005fbase64_005fdecode2">gnutls_srp_base64_decode2</a> (const gnutls_datum_t * <var>b64_data</var>, gnutls_datum_t * <var>result</var>)</code></dt>
</dl>

<hr>
<a name="srptool-Invocation"></a>
<div class="header">
<p>
Previous: <a href="#Authentication-using-SRP" accesskey="p" rel="prev">Authentication using SRP</a>, Up: <a href="#SRP-authentication" accesskey="u" rel="up">SRP authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Invoking-srptool"></a>
<h4 class="subsubsection">4.3.1.2 Invoking srptool</h4>
<a name="index-srptool"></a>


<p>Simple program that emulates the programs in the Stanford SRP (Secure
Remote Password) libraries using GnuTLS.  It is intended for use in  places
where you don&rsquo;t expect SRP authentication to be the used for system users.
</p>
<p>In  brief,  to use SRP you need to create two files. These are the password
file that holds the users and the verifiers associated with  them  and  the
configuration file to hold the group parameters (called tpasswd.conf).
</p>
<p>This section was generated by <strong>AutoGen</strong>,
using the <code>agtexi-cmd</code> template and the option descriptions for the <code>srptool</code> program.
This software is released under the GNU General Public License, version 3 or later.
</p>

<a name="srptool-usage"></a><a name="srptool-help_002fusage-_0028_002d_002dhelp_0029"></a>
<h4 class="subsubheading">srptool help/usage (<samp>--help</samp>)</h4>
<a name="index-srptool-help"></a>

<p>This is the automatically generated usage text for srptool.
</p>
<p>The text printed is the same whether selected with the <code>help</code> option
(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>).  <code>more-help</code> will print
the usage text by passing it through a pager program.
<code>more-help</code> is disabled on platforms without a working
<code>fork(2)</code> function.  The <code>PAGER</code> environment variable is
used to select the program, defaulting to <samp>more</samp>.  Both will exit
with a status code of 0.
</p>
<div class="example">
<pre class="example">srptool - GnuTLS SRP tool
Usage:  srptool [ -&lt;flag&gt; [&lt;val&gt;] | --&lt;name&gt;[{=| }&lt;val&gt;] ]...

   -d, --debug=num            Enable debugging
                                - it must be in the range:
                                  0 to 9999
   -i, --index=num            specify the index of the group parameters in tpasswd.conf to use
   -u, --username=str         specify a username
   -p, --passwd=str           specify a password file
   -s, --salt=num             specify salt size
       --verify               just verify the password.
   -v, --passwd-conf=str      specify a password conf file.
       --create-conf=str      Generate a password configuration file.
   -v, --version[=arg]        output version information and exit
   -h, --help                 display extended usage information and exit
   -!, --more-help            extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.

Simple program that emulates the programs in the Stanford SRP (Secure
Remote Password) libraries using GnuTLS.  It is intended for use in places
where you don't expect SRP authentication to be the used for system users.

In brief, to use SRP you need to create two files.  These are the password
file that holds the users and the verifiers associated with them and the
configuration file to hold the group parameters (called tpasswd.conf).

</pre></div>

<a name="srptool-debug"></a><a name="debug-option-_0028_002dd_0029-4"></a>
<h4 class="subsubheading">debug option (-d)</h4>

<p>This is the &ldquo;enable debugging&rdquo; option.
This option takes a number argument.
Specifies the debug level.
<a name="srptool-verify"></a></p><a name="verify-option-1"></a>
<h4 class="subsubheading">verify option</h4>

<p>This is the &ldquo;just verify the password.&rdquo; option.
Verifies the password provided against the password file.
<a name="srptool-passwd_002dconf"></a></p><a name="passwd_002dconf-option-_0028_002dv_0029"></a>
<h4 class="subsubheading">passwd-conf option (-v)</h4>

<p>This is the &ldquo;specify a password conf file.&rdquo; option.
This option takes a string argument.
Specify a filename or a PKCS #11 URL to read the CAs from.
<a name="srptool-create_002dconf"></a></p><a name="create_002dconf-option"></a>
<h4 class="subsubheading">create-conf option</h4>

<p>This is the &ldquo;generate a password configuration file.&rdquo; option.
This option takes a string argument.
This generates a password configuration file (tpasswd.conf)
containing the required for TLS parameters.
<a name="srptool-exit-status"></a></p><a name="srptool-exit-status-1"></a>
<h4 class="subsubheading">srptool exit status</h4>

<p>One of the following exit values will be returned:
</p><dl compact="compact">
<dt>&lsquo;<samp>0 (EXIT_SUCCESS)</samp>&rsquo;</dt>
<dd><p>Successful program execution.
</p></dd>
<dt>&lsquo;<samp>1 (EXIT_FAILURE)</samp>&rsquo;</dt>
<dd><p>The operation failed or the command syntax was not valid.
</p></dd>
</dl>
<a name="srptool-See-Also"></a><a name="srptool-See-Also-1"></a>
<h4 class="subsubheading">srptool See Also</h4>
<p>gnutls-cli-debug (1), gnutls-serv (1), srptool (1), psktool (1), certtool (1)
<a name="srptool-Examples"></a></p><a name="srptool-Examples-1"></a>
<h4 class="subsubheading">srptool Examples</h4>
<p>To create <samp>tpasswd.conf</samp> which holds the g and n values for SRP protocol
(generator and a large prime), run:
</p><div class="example">
<pre class="example">$ srptool --create-conf /etc/tpasswd.conf
</pre></div>

<p>This command will create <samp>/etc/tpasswd</samp> and will add user &rsquo;test&rsquo; (you
will also be prompted for a password). Verifiers are stored by default
in the way libsrp expects.
</p><div class="example">
<pre class="example">$ srptool --passwd /etc/tpasswd --passwd-conf /etc/tpasswd.conf -u test
</pre></div>


<p>This command will check against a password. If the password matches
the one in <samp>/etc/tpasswd</samp> you will get an ok.
</p><div class="example">
<pre class="example">$ srptool --passwd /etc/tpasswd --passwd\-conf /etc/tpasswd.conf --verify -u test
</pre></div>

<hr>
<a name="PSK-authentication"></a>
<div class="header">
<p>
Next: <a href="#Anonymous-authentication" accesskey="n" rel="next">Anonymous authentication</a>, Previous: <a href="#SRP-authentication" accesskey="p" rel="prev">SRP authentication</a>, Up: <a href="#Shared_002dkey-and-anonymous-authentication" accesskey="u" rel="up">Shared-key and anonymous authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="PSK-authentication-1"></a>
<h4 class="subsection">4.3.2 PSK authentication</h4>

<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Authentication-using-PSK" accesskey="1">Authentication using PSK</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#psktool-Invocation" accesskey="2">psktool Invocation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Invoking psktool
</td></tr>
</table>

<hr>
<a name="Authentication-using-PSK"></a>
<div class="header">
<p>
Next: <a href="#psktool-Invocation" accesskey="n" rel="next">psktool Invocation</a>, Up: <a href="#PSK-authentication" accesskey="u" rel="up">PSK authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Authentication-using-PSK-1"></a>
<h4 class="subsubsection">4.3.2.1 Authentication using <acronym>PSK</acronym></h4>
<a name="index-PSK-authentication"></a>

<p>Authentication using Pre-shared keys is a method to authenticate using
usernames and binary keys. This protocol avoids making use of public
key infrastructure and expensive calculations, thus it is suitable for
constraint clients.
</p>
<p>The implementation in <acronym>GnuTLS</acronym> is based on [<em>TLSPSK</em>].  
The supported <acronym>PSK</acronym> key exchange methods are:
</p>
<dl compact="compact">
<dt><code>PSK:</code></dt>
<dd><p>Authentication using the <acronym>PSK</acronym> protocol.
</p>
</dd>
<dt><code>DHE-PSK:</code></dt>
<dd><p>Authentication using the <acronym>PSK</acronym> protocol and Diffie-Hellman key
exchange.  This method offers perfect forward secrecy.
</p>
</dd>
<dt><code>ECDHE-PSK:</code></dt>
<dd><p>Authentication using the <acronym>PSK</acronym> protocol and Elliptic curve Diffie-Hellman key
exchange.  This method offers perfect forward secrecy.
</p>
</dd>
<dt><code>RSA-PSK:</code></dt>
<dd><p>Authentication using the <acronym>PSK</acronym> protocol for the client and an RSA certificate
for the server.
</p>
</dd>
</dl>


<p>Helper functions to generate and maintain <acronym>PSK</acronym> keys are also included
in <acronym>GnuTLS</acronym>.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fkey_005fgenerate">gnutls_key_generate</a> (gnutls_datum_t * <var>key</var>, unsigned int <var>key_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fhex_005fencode">gnutls_hex_encode</a> (const gnutls_datum_t * <var>data</var>, char * <var>result</var>, size_t * <var>result_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fhex_005fdecode">gnutls_hex_decode</a> (const gnutls_datum_t * <var>hex_data</var>, void * <var>result</var>, size_t * <var>result_size</var>)</code></dt>
</dl>

<hr>
<a name="psktool-Invocation"></a>
<div class="header">
<p>
Previous: <a href="#Authentication-using-PSK" accesskey="p" rel="prev">Authentication using PSK</a>, Up: <a href="#PSK-authentication" accesskey="u" rel="up">PSK authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Invoking-psktool"></a>
<h4 class="subsubsection">4.3.2.2 Invoking psktool</h4>
<a name="index-psktool"></a>


<p>Program  that generates random keys for use with TLS-PSK. The
keys are stored in hexadecimal format in a key file.
</p>
<p>This section was generated by <strong>AutoGen</strong>,
using the <code>agtexi-cmd</code> template and the option descriptions for the <code>psktool</code> program.
This software is released under the GNU General Public License, version 3 or later.
</p>

<a name="psktool-usage"></a><a name="psktool-help_002fusage-_0028_002d_002dhelp_0029"></a>
<h4 class="subsubheading">psktool help/usage (<samp>--help</samp>)</h4>
<a name="index-psktool-help"></a>

<p>This is the automatically generated usage text for psktool.
</p>
<p>The text printed is the same whether selected with the <code>help</code> option
(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>).  <code>more-help</code> will print
the usage text by passing it through a pager program.
<code>more-help</code> is disabled on platforms without a working
<code>fork(2)</code> function.  The <code>PAGER</code> environment variable is
used to select the program, defaulting to <samp>more</samp>.  Both will exit
with a status code of 0.
</p>
<div class="example">
<pre class="example">psktool - GnuTLS PSK tool
Usage:  psktool [ -&lt;flag&gt; [&lt;val&gt;] | --&lt;name&gt;[{=| }&lt;val&gt;] ]...

   -d, --debug=num            Enable debugging
                                - it must be in the range:
                                  0 to 9999
   -s, --keysize=num          specify the key size in bytes
                                - it must be in the range:
                                  0 to 512
   -u, --username=str         specify a username
   -p, --passwd=str           specify a password file
   -v, --version[=arg]        output version information and exit
   -h, --help                 display extended usage information and exit
   -!, --more-help            extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.

Program that generates random keys for use with TLS-PSK.  The keys are
stored in hexadecimal format in a key file.

</pre></div>

<a name="psktool-debug"></a><a name="debug-option-_0028_002dd_0029-5"></a>
<h4 class="subsubheading">debug option (-d)</h4>

<p>This is the &ldquo;enable debugging&rdquo; option.
This option takes a number argument.
Specifies the debug level.
<a name="psktool-exit-status"></a></p><a name="psktool-exit-status-1"></a>
<h4 class="subsubheading">psktool exit status</h4>

<p>One of the following exit values will be returned:
</p><dl compact="compact">
<dt>&lsquo;<samp>0 (EXIT_SUCCESS)</samp>&rsquo;</dt>
<dd><p>Successful program execution.
</p></dd>
<dt>&lsquo;<samp>1 (EXIT_FAILURE)</samp>&rsquo;</dt>
<dd><p>The operation failed or the command syntax was not valid.
</p></dd>
</dl>
<a name="psktool-See-Also"></a><a name="psktool-See-Also-1"></a>
<h4 class="subsubheading">psktool See Also</h4>
<p>gnutls-cli-debug (1), gnutls-serv (1), srptool (1), certtool (1)
<a name="psktool-Examples"></a></p><a name="psktool-Examples-1"></a>
<h4 class="subsubheading">psktool Examples</h4>
<p>To add a user &rsquo;psk_identity&rsquo; in <samp>passwd.psk</samp> for use with GnuTLS run:
</p><div class="example">
<pre class="example">$ ./psktool -u psk_identity -p passwd.psk
Generating a random key for user 'psk_identity'
Key stored to passwd.psk
$ cat psks.txt
psk_identity:88f3824b3e5659f52d00e959bacab954b6540344
$
</pre></div>

<p>This command will create <samp>passwd.psk</samp> if it does not exist
and will add user &rsquo;psk_identity&rsquo; (you will also be prompted for a password).
</p>
<hr>
<a name="Anonymous-authentication"></a>
<div class="header">
<p>
Previous: <a href="#PSK-authentication" accesskey="p" rel="prev">PSK authentication</a>, Up: <a href="#Shared_002dkey-and-anonymous-authentication" accesskey="u" rel="up">Shared-key and anonymous authentication</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Anonymous-authentication-1"></a>
<h4 class="subsection">4.3.3 Anonymous authentication</h4>
<a name="index-anonymous-authentication"></a>

<p>The anonymous key exchange offers encryption without any
indication of the peer&rsquo;s identity.  This kind of authentication
is vulnerable to a man in the middle attack, but can be
used even if there is no prior communication or shared trusted parties 
with the peer. It is useful to establish a session over which certificate
authentication will occur in order to hide the indentities of the participants
from passive eavesdroppers.
</p>
<p>Unless in the above case, it is not recommended to use anonymous authentication. 
In the cases where there is no prior communication with the peers, 
an alternative with better properties, such as key continuity, is trust on first use
(see <a href="#Verifying-a-certificate-using-trust-on-first-use-authentication">Verifying a certificate using trust on first use authentication</a>).
</p>
<p>The available key exchange algorithms for anonymous authentication are
shown below, but note that few public servers support them, and they 
have to be explicitly enabled.
</p>
<dl compact="compact">
<dt><code>ANON_DH:</code></dt>
<dd><p>This algorithm exchanges Diffie-Hellman parameters.
</p>
</dd>
<dt><code>ANON_ECDH:</code></dt>
<dd><p>This algorithm exchanges elliptic curve Diffie-Hellman parameters. It is more 
efficient than ANON_DH on equivalent security levels.
</p>
</dd>
</dl>

<hr>
<a name="Selecting-an-appropriate-authentication-method"></a>
<div class="header">
<p>
Previous: <a href="#Shared_002dkey-and-anonymous-authentication" accesskey="p" rel="prev">Shared-key and anonymous authentication</a>, Up: <a href="#Authentication-methods" accesskey="u" rel="up">Authentication methods</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Selecting-an-appropriate-authentication-method-1"></a>
<h3 class="section">4.4 Selecting an appropriate authentication method</h3>

<p>This section provides some guidance on how to use the available authentication
methods in <acronym>GnuTLS</acronym> in various scenarios.
</p>
<a name="Two-peers-with-an-out_002dof_002dband-channel"></a>
<h4 class="subsection">4.4.1 Two peers with an out-of-band channel</h4>

<p>Let&rsquo;s consider two peers who need to communicate over an untrusted channel
(the Internet), but have an out-of-band channel available. The latter
channel is considered safe from eavesdropping and message modification and thus
can be used for an initial bootstrapping of the protocol. The options 
available are:
</p><ul>
<li> Pre-shared keys (see <a href="#PSK-authentication">PSK authentication</a>). The server and a
client communicate a shared randomly generated key over the trusted
channel and use it to negotiate further sessions over the untrusted channel.

</li><li> Passwords (see <a href="#SRP-authentication">SRP authentication</a>). The client communicates
to the server its username and password of choice and uses it to
negotiate further sessions over the untrusted channel.

</li><li> Public keys (see <a href="#Certificate-authentication">Certificate authentication</a>). The client 
and the server exchange their public keys (or fingerprints of them)
over the trusted channel. 
On future sessions over the untrusted channel they verify the key
being the same (similar to <a href="#Verifying-a-certificate-using-trust-on-first-use-authentication">Verifying a certificate using trust on first use authentication</a>).
</li></ul>

<p>Provided that the out-of-band channel is trusted all of the above provide
a similar level of protection. An out-of-band channel may be the initial
bootstrapping of a user&rsquo;s PC in a corporate environment, in-person
communication, communication over an alternative network (e.g. the phone
network), etc.
</p>
<a name="Two-peers-without-an-out_002dof_002dband-channel"></a>
<h4 class="subsection">4.4.2 Two peers without an out-of-band channel</h4>

<p>When an out-of-band channel is not available a peer cannot be reliably
authenticated. What can be done, however, is to allow some form of
registration of users connecting for the first time and ensure that their
keys remain the same after that initial connection. This is termed
key continuity or trust on first use (TOFU).
</p>
<p>The available option is to use public key authentication (see <a href="#Certificate-authentication">Certificate authentication</a>). 
The client and the server store each other&rsquo;s public keys (or fingerprints of them)
and associate them with their identity.
On future sessions over the untrusted channel they verify the keys
being the same (see <a href="#Verifying-a-certificate-using-trust-on-first-use-authentication">Verifying a certificate using trust on first use authentication</a>).
</p>
<p>To mitigate the uncertainty of the information exchanged in the first 
connection other channels over the Internet may be used, e.g., <acronym>DNSSEC</acronym>
(see <a href="#Verifying-a-certificate-using-DANE">Verifying a certificate using DANE</a>).
</p>
<a name="Two-peers-and-a-trusted-third-party"></a>
<h4 class="subsection">4.4.3 Two peers and a trusted third party</h4>

<p>When a trusted third party is available (or a certificate authority) 
the most suitable option is to use 
certificate authentication (see <a href="#Certificate-authentication">Certificate authentication</a>). 
The client and the server obtain certificates that associate their identity
and public keys using a digital signature by the trusted party and use 
them to on the subsequent communications with each other. 
Each party verifies the peer&rsquo;s certificate using the trusted third party&rsquo;s 
signature. The parameters of the third party&rsquo;s signature are present
in its certificate which must be available to all communicating parties.
</p>
<p>While the above is the typical authentication method for servers in the
Internet by using the commercial CAs, the users that act as clients in the
protocol rarely possess such certificates. In that case a hybrid method
can be used where the server is authenticated by the client using the
commercial CAs and the client is authenticated based on some information
the client provided over the initial server-authenticated channel. The
available options are:
</p><ul>
<li> Passwords (see <a href="#SRP-authentication">SRP authentication</a>). The client communicates
to the server its username and password of choice on the initial
server-authenticated connection and uses it to negotiate further sessions. 
This is possible because the SRP protocol allows for the server to be 
authenticated using a certificate and the client using the
password.

</li><li> Public keys (see <a href="#Certificate-authentication">Certificate authentication</a>). The client 
sends its public key to the server (or a fingerprint of it) over the
initial server-authenticated connection. 
On future sessions the client verifies the server using the third party
certificate and the server verifies that the client&rsquo;s public key remained 
the same (see <a href="#Verifying-a-certificate-using-trust-on-first-use-authentication">Verifying a certificate using trust on first use authentication</a>).
</li></ul>


<hr>
<a name="Hardware-security-modules-and-abstract-key-types"></a>
<div class="header">
<p>
Next: <a href="#How-to-use-GnuTLS-in-applications" accesskey="n" rel="next">How to use GnuTLS in applications</a>, Previous: <a href="#Authentication-methods" accesskey="p" rel="prev">Authentication methods</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Abstract-keys-types-and-Hardware-security-modules"></a>
<h2 class="chapter">5 Abstract keys types and Hardware security modules</h2>

<p>In several cases storing the long term cryptographic keys in a hard disk or
even in memory poses a significant risk. Once the system they are stored
is compromised the keys must be replaced as the secrecy of future sessions
is no longer guarranteed. Moreover, past sessions that were not protected by a
perfect forward secrecy offering ciphersuite are also to be assumed compromised.
</p>
<p>If such threats need to be addressed, then it may be wise storing the keys in a security
module such as a smart card, an HSM or the TPM chip. Those modules ensure the
protection of the cryptographic keys by only allowing operations on them and
preventing their extraction. The purpose of the abstract key API is to provide
an API that will allow the handle of keys in memory and files, as well as keys
stored in such modules.
</p>
<p>In GnuTLS the approach is to handle all keys transparently by the high level API, e.g.,
the API that loads a key or certificate from a file.
The high-level API will accept URIs in addition to files that specify keys on an HSM or in TPM,
and a callback function will be used to obtain any required keys. The URI format is defined in 
[<em>TPMURI</em>] and the standardized [<em>PKCS11URI</em>].
</p>
<p>More information on the API is provided in the next sections. Examples of a URI of a certificate 
stored in an HSM, as well as a key stored in the TPM chip are shown below. To discover the URIs 
of the objects the <code>p11tool</code> (see <a href="#p11tool-Invocation">p11tool Invocation</a>),
or <code>tpmtool</code> (see <a href="#tpmtool-Invocation">tpmtool Invocation</a>) may be used.
</p>
<div class="example">
<pre class="example">pkcs11:token=Nikos;serial=307521161601031;model=PKCS%2315; \
manufacturer=EnterSafe;object=test1;type=cert

tpmkey:uuid=42309df8-d101-11e1-a89a-97bb33c23ad1;storage=user
</pre></div>


<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Abstract-key-types" accesskey="1">Abstract key types</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Application_002dspecific-keys" accesskey="2">Application-specific keys</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Smart-cards-and-HSMs" accesskey="3">Smart cards and HSMs</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Trusted-Platform-Module" accesskey="4">Trusted Platform Module</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Abstract-key-types"></a>
<div class="header">
<p>
Next: <a href="#Application_002dspecific-keys" accesskey="n" rel="next">Application-specific keys</a>, Up: <a href="#Hardware-security-modules-and-abstract-key-types" accesskey="u" rel="up">Hardware security modules and abstract key types</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Abstract-key-types-1"></a>
<h3 class="section">5.1 Abstract key types</h3>
<a name="index-abstract-types"></a>

<p>Since there are many forms of a public or private keys supported by <acronym>GnuTLS</acronym> such as
<acronym>X.509</acronym>, <acronym>OpenPGP</acronym>, <acronym>PKCS</acronym> #11 or TPM it is desirable to allow common operations
on them. For these reasons the abstract <code>gnutls_privkey_t</code> and <code>gnutls_pubkey_t</code> were
introduced in <code>gnutls/abstract.h</code> header. Those types are initialized using a specific type of 
key and then can be used to perform operations in an abstract way. For example in order
to sign an X.509 certificate with a key that resides in a token the following steps can be
used.
</p>
<div class="example">
<pre class="example">#inlude &lt;gnutls/abstract.h&gt;

void sign_cert( gnutls_x509_crt_t to_be_signed)
{
gnutls_x509_crt_t ca_cert;
gnutls_privkey_t abs_key;

  /* initialize the abstract key */
  gnutls_privkey_init(&amp;abs_key);

  /* keys stored in tokens are identified by URLs */
  gnutls_privkey_import_url(abs_key, key_url);

  gnutls_x509_crt_init(&amp;ca_cert);
  gnutls_x509_crt_import_url(&amp;ca_cert, cert_url);

  /* sign the certificate to be signed */
  gnutls_x509_crt_privkey_sign(to_be_signed, ca_cert, abs_key, 
                               GNUTLS_DIG_SHA256, 0);
}
</pre></div>

<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Abstract-public-keys" accesskey="1">Abstract public keys</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Abstract-private-keys" accesskey="2">Abstract private keys</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Operations" accesskey="3">Operations</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Abstract-public-keys"></a>
<div class="header">
<p>
Next: <a href="#Abstract-private-keys" accesskey="n" rel="next">Abstract private keys</a>, Up: <a href="#Abstract-key-types" accesskey="u" rel="up">Abstract key types</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Public-keys"></a>
<h4 class="subsection">5.1.1 Public keys</h4>
<p>An abstract <code>gnutls_pubkey_t</code> can be initialized
using the functions below. It can be imported through
an existing structure like <code>gnutls_x509_crt_t</code>,
or through an ASN.1 encoding of the X.509 <code>SubjectPublicKeyInfo</code>
sequence.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fimport_005fx509">gnutls_pubkey_import_x509</a> (gnutls_pubkey_t <var>key</var>, gnutls_x509_crt_t <var>crt</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fimport_005fopenpgp">gnutls_pubkey_import_openpgp</a> (gnutls_pubkey_t <var>key</var>, gnutls_openpgp_crt_t <var>crt</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fimport_005fpkcs11">gnutls_pubkey_import_pkcs11</a> (gnutls_pubkey_t <var>key</var>, gnutls_pkcs11_obj_t <var>obj</var>, unsigned int <var>flags</var>)</code></dt>
</dl>

<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fimport_005furl">gnutls_pubkey_import_url</a> (gnutls_pubkey_t <var>key</var>, const char * <var>url</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fimport_005fprivkey">gnutls_pubkey_import_privkey</a> (gnutls_pubkey_t <var>key</var>, gnutls_privkey_t <var>pkey</var>, unsigned int <var>usage</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fimport">gnutls_pubkey_import</a> (gnutls_pubkey_t <var>key</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fexport">gnutls_pubkey_export</a> (gnutls_pubkey_t <var>key</var>, gnutls_x509_crt_fmt_t <var>format</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</code></dt>
</dl>





<dl>
<dt><a name="index-gnutls_005fpubkey_005fexport2"></a>Function: <em>int</em> <strong>gnutls_pubkey_export2</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_x509_crt_fmt_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>key</var>: Holds the certificate
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>out</var>: will contain a certificate PEM or DER encoded
</p>
<p>This function will export the public key to DER or PEM format.
The contents of the exported data is the SubjectPublicKeyInfo
X.509 structure.
</p>
<p>The output buffer will be allocated using <code>gnutls_malloc()</code> .
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN CERTIFICATE&quot;.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<p>Other helper functions that allow directly importing from raw X.509 or
OpenPGP structures are shown below. 
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fimport_005fx509_005fraw">gnutls_pubkey_import_x509_raw</a> (gnutls_pubkey_t <var>pkey</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fimport_005fopenpgp_005fraw">gnutls_pubkey_import_openpgp_raw</a> (gnutls_pubkey_t <var>pkey</var>, const gnutls_datum_t * <var>data</var>, gnutls_openpgp_crt_fmt_t <var>format</var>, const gnutls_openpgp_keyid_t <var>keyid</var>, unsigned int <var>flags</var>)</code></dt>
</dl>

<p>An important function is <a href="#gnutls_005fpubkey_005fimport_005furl">gnutls_pubkey_import_url</a> which will import
public keys from URLs that identify objects stored in tokens (see <a href="#Smart-cards-and-HSMs">Smart cards and HSMs</a> and <a href="#Trusted-Platform-Module">Trusted Platform Module</a>).
A function to check for a supported by GnuTLS URL is <a href="#gnutls_005furl_005fis_005fsupported">gnutls_url_is_supported</a>.
</p>




<dl>
<dt><a name="index-gnutls_005furl_005fis_005fsupported"></a>Function: <em>int</em> <strong>gnutls_url_is_supported</strong> <em>(const char * <var>url</var>)</em></dt>
<dd><p><var>url</var>: A PKCS 11 url
</p>
<p>Check whether url is supported.  Depending on the system libraries
GnuTLS may support pkcs11 or tpmkey URLs.
</p>
<p><strong>Returns:</strong> return non-zero if the given URL is supported, and zero if
it is not known.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<p>Additional functions are available that will return
information over a public key, such as a unique key ID, as well as a function 
that given a public key fingerprint would provide a memorable sketch.
</p>
<p>Note that <a href="#gnutls_005fpubkey_005fget_005fkey_005fid">gnutls_pubkey_get_key_id</a> calculates a SHA1 digest of the 
public key as a DER-formatted, subjectPublicKeyInfo object.  Other implementations 
use different approaches, e.g., some use the &ldquo;common method&rdquo; described in
section 4.2.1.2 of [<em>RFC5280</em>] which calculates a digest on a part of the
subjectPublicKeyInfo object.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fget_005fpk_005falgorithm">gnutls_pubkey_get_pk_algorithm</a> (gnutls_pubkey_t <var>key</var>, unsigned int * <var>bits</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fget_005fpreferred_005fhash_005falgorithm">gnutls_pubkey_get_preferred_hash_algorithm</a> (gnutls_pubkey_t <var>key</var>, gnutls_digest_algorithm_t *         <var>hash</var>, unsigned int * <var>mand</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fget_005fkey_005fid">gnutls_pubkey_get_key_id</a> (gnutls_pubkey_t <var>key</var>, unsigned int <var>flags</var>, unsigned char * <var>output_data</var>, size_t * <var>output_data_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005frandom_005fart">gnutls_random_art</a> (gnutls_random_art_t <var>type</var>, const char * <var>key_type</var>, unsigned int <var>key_size</var>, void * <var>fpr</var>, size_t <var>fpr_size</var>, gnutls_datum_t * <var>art</var>)</code></dt>
</dl>

<p>To export the key-specific parameters, or obtain a unique key ID the following functions are provided.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fexport_005frsa_005fraw">gnutls_pubkey_export_rsa_raw</a> (gnutls_pubkey_t <var>key</var>, gnutls_datum_t * <var>m</var>, gnutls_datum_t * <var>e</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fexport_005fdsa_005fraw">gnutls_pubkey_export_dsa_raw</a> (gnutls_pubkey_t <var>key</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>g</var>, gnutls_datum_t * <var>y</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fexport_005fecc_005fraw">gnutls_pubkey_export_ecc_raw</a> (gnutls_pubkey_t <var>key</var>, gnutls_ecc_curve_t * <var>curve</var>, gnutls_datum_t * <var>x</var>, gnutls_datum_t * <var>y</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fexport_005fecc_005fx962">gnutls_pubkey_export_ecc_x962</a> (gnutls_pubkey_t <var>key</var>, gnutls_datum_t * <var>parameters</var>, gnutls_datum_t * <var>ecpoint</var>)</code></dt>
</dl>

<hr>
<a name="Abstract-private-keys"></a>
<div class="header">
<p>
Next: <a href="#Operations" accesskey="n" rel="next">Operations</a>, Previous: <a href="#Abstract-public-keys" accesskey="p" rel="prev">Abstract public keys</a>, Up: <a href="#Abstract-key-types" accesskey="u" rel="up">Abstract key types</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Private-keys"></a>
<h4 class="subsection">5.1.2 Private keys</h4>
<p>An abstract <code>gnutls_privkey_t</code> can be initialized
using the functions below. It can be imported through
an existing structure like <code>gnutls_x509_privkey_t</code>,
but unlike public keys it cannot be exported. That is
to allow abstraction over keys stored in hardware that 
makes available only operations.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fprivkey_005fimport_005fx509">gnutls_privkey_import_x509</a> (gnutls_privkey_t <var>pkey</var>, gnutls_x509_privkey_t <var>key</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fprivkey_005fimport_005fopenpgp">gnutls_privkey_import_openpgp</a> (gnutls_privkey_t <var>pkey</var>, gnutls_openpgp_privkey_t <var>key</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fprivkey_005fimport_005fpkcs11">gnutls_privkey_import_pkcs11</a> (gnutls_privkey_t <var>pkey</var>, gnutls_pkcs11_privkey_t <var>key</var>, unsigned int <var>flags</var>)</code></dt>
</dl>

<p>Other helper functions that allow directly importing from raw X.509 or
OpenPGP structures are shown below. Again, as with public keys, private keys 
can be imported from a hardware module using URLs.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fprivkey_005fimport_005fx509_005fraw">gnutls_privkey_import_x509_raw</a> (gnutls_privkey_t <var>pkey</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fprivkey_005fimport_005fopenpgp_005fraw">gnutls_privkey_import_openpgp_raw</a> (gnutls_privkey_t <var>pkey</var>, const gnutls_datum_t * <var>data</var>, gnutls_openpgp_crt_fmt_t <var>format</var>, const gnutls_openpgp_keyid_t <var>keyid</var>, const char * <var>password</var>)</code></dt>
</dl>





<dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005furl"></a>Function: <em>int</em> <strong>gnutls_privkey_import_url</strong> <em>(gnutls_privkey_t <var>key</var>, const char * <var>url</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: A key of type <code>gnutls_privkey_t</code> 
</p>
<p><var>url</var>: A PKCS 11 url
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will import a PKCS11 or TPM URL as a
private key. The supported URL types can be checked
using <code>gnutls_url_is_supported()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fprivkey_005fget_005fpk_005falgorithm">gnutls_privkey_get_pk_algorithm</a> (gnutls_privkey_t <var>key</var>, unsigned int * <var>bits</var>)</code></dt>
<dt><code><var>gnutls_privkey_type_t</var> <a href="#gnutls_005fprivkey_005fget_005ftype">gnutls_privkey_get_type</a> (gnutls_privkey_t <var>key</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fprivkey_005fstatus">gnutls_privkey_status</a> (gnutls_privkey_t <var>key</var>)</code></dt>
</dl>

<p>In order to support cryptographic operations using 
an external API, the following function is provided.
This allows for a simple extensibility API without
resorting to <acronym>PKCS</acronym> #11.
</p>




<dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fext3"></a>Function: <em>int</em> <strong>gnutls_privkey_import_ext3</strong> <em>(gnutls_privkey_t <var>pkey</var>, void * <var>userdata</var>, gnutls_privkey_sign_func <var>sign_fn</var>, gnutls_privkey_decrypt_func <var>decrypt_fn</var>, gnutls_privkey_deinit_func <var>deinit_fn</var>, gnutls_privkey_info_func <var>info_fn</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>userdata</var>: private data to be provided to the callbacks
</p>
<p><var>sign_fn</var>: callback for signature operations
</p>
<p><var>decrypt_fn</var>: callback for decryption operations
</p>
<p><var>deinit_fn</var>: a deinitialization function
</p>
<p><var>info_fn</var>: returns info about the public key algorithm (should not be <code>NULL</code> )
</p>
<p><var>flags</var>: Flags for the import
</p>
<p>This function will associate the given callbacks with the
<code>gnutls_privkey_t</code>  type. At least one of the two callbacks
must be non-null. If a deinitialization function is provided
then flags is assumed to contain <code>GNUTLS_PRIVKEY_IMPORT_AUTO_RELEASE</code> .
</p>
<p>Note that the signing function is supposed to &quot;raw&quot; sign data, i.e.,
without any hashing or preprocessing. In case of RSA the DigestInfo
will be provided, and the signing function is expected to do the PKCS <code>1</code> 
1.5 padding and the exponentiation.
</p>
<p>The  <code>info_fn</code> must provide information on the algorithms supported by
this private key, and should support the flags <code>GNUTLS_PRIVKEY_INFO_PK_ALGO</code>  and
<code>GNUTLS_PRIVKEY_INFO_SIGN_ALGO</code> . It must return -1 on unknown flags.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<hr>
<a name="Operations"></a>
<div class="header">
<p>
Previous: <a href="#Abstract-private-keys" accesskey="p" rel="prev">Abstract private keys</a>, Up: <a href="#Abstract-key-types" accesskey="u" rel="up">Abstract key types</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Operations-1"></a>
<h4 class="subsection">5.1.3 Operations</h4>
<p>The abstract key types can be used to access signing and
signature verification operations with the underlying keys.
</p>




<dl>
<dt><a name="index-gnutls_005fpubkey_005fverify_005fdata2"></a>Function: <em>int</em> <strong>gnutls_pubkey_verify_data2</strong> <em>(gnutls_pubkey_t <var>pubkey</var>, gnutls_sign_algorithm_t <var>algo</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>data</var>, const gnutls_datum_t * <var>signature</var>)</em></dt>
<dd><p><var>pubkey</var>: Holds the public key
</p>
<p><var>algo</var>: The signature algorithm used
</p>
<p><var>flags</var>: Zero or an OR list of <code>gnutls_certificate_verify_flags</code> 
</p>
<p><var>data</var>: holds the signed data
</p>
<p><var>signature</var>: contains the signature
</p>
<p>This function will verify the given signed data, using the
parameters from the certificate.
</p>
<p><strong>Returns:</strong> In case of a verification failure <code>GNUTLS_E_PK_SIG_VERIFY_FAILED</code>  
is returned, and zero or positive code on success. For known to be insecure
signatures this function will return <code>GNUTLS_E_INSUFFICIENT_SECURITY</code>  unless
the flag <code>GNUTLS_VERIFY_ALLOW_BROKEN</code>  is specified.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fpubkey_005fverify_005fhash2"></a>Function: <em>int</em> <strong>gnutls_pubkey_verify_hash2</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_sign_algorithm_t <var>algo</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>hash</var>, const gnutls_datum_t * <var>signature</var>)</em></dt>
<dd><p><var>key</var>: Holds the public key
</p>
<p><var>algo</var>: The signature algorithm used
</p>
<p><var>flags</var>: Zero or an OR list of <code>gnutls_certificate_verify_flags</code> 
</p>
<p><var>hash</var>: holds the hash digest to be verified
</p>
<p><var>signature</var>: contains the signature
</p>
<p>This function will verify the given signed digest, using the
parameters from the public key. Note that unlike <code>gnutls_privkey_sign_hash()</code> ,
this function accepts a signature algorithm instead of a digest algorithm.
You can use <code>gnutls_pk_to_sign()</code>  to get the appropriate value.
</p>
<p><strong>Returns:</strong> In case of a verification failure <code>GNUTLS_E_PK_SIG_VERIFY_FAILED</code>  
is returned, and zero or positive code on success.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fpubkey_005fencrypt_005fdata"></a>Function: <em>int</em> <strong>gnutls_pubkey_encrypt_data</strong> <em>(gnutls_pubkey_t <var>key</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>plaintext</var>, gnutls_datum_t * <var>ciphertext</var>)</em></dt>
<dd><p><var>key</var>: Holds the public key
</p>
<p><var>flags</var>: should be 0 for now
</p>
<p><var>plaintext</var>: The data to be encrypted
</p>
<p><var>ciphertext</var>: contains the encrypted data
</p>
<p>This function will encrypt the given data, using the public
key.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>





<dl>
<dt><a name="index-gnutls_005fprivkey_005fsign_005fdata"></a>Function: <em>int</em> <strong>gnutls_privkey_sign_data</strong> <em>(gnutls_privkey_t <var>signer</var>, gnutls_digest_algorithm_t <var>hash</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>data</var>, gnutls_datum_t * <var>signature</var>)</em></dt>
<dd><p><var>signer</var>: Holds the key
</p>
<p><var>hash</var>: should be a digest algorithm
</p>
<p><var>flags</var>: Zero or one of <code>gnutls_privkey_flags_t</code> 
</p>
<p><var>data</var>: holds the data to be signed
</p>
<p><var>signature</var>: will contain the signature allocated with <code>gnutls_malloc()</code> 
</p>
<p>This function will sign the given data using a signature algorithm
supported by the private key. Signature algorithms are always used
together with a hash functions.  Different hash functions may be
used for the RSA algorithm, but only the SHA family for the DSA keys.
</p>
<p>You may use <code>gnutls_pubkey_get_preferred_hash_algorithm()</code>  to determine
the hash algorithm.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fprivkey_005fsign_005fhash"></a>Function: <em>int</em> <strong>gnutls_privkey_sign_hash</strong> <em>(gnutls_privkey_t <var>signer</var>, gnutls_digest_algorithm_t <var>hash_algo</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>hash_data</var>, gnutls_datum_t * <var>signature</var>)</em></dt>
<dd><p><var>signer</var>: Holds the signer&rsquo;s key
</p>
<p><var>hash_algo</var>: The hash algorithm used
</p>
<p><var>flags</var>: Zero or one of <code>gnutls_privkey_flags_t</code> 
</p>
<p><var>hash_data</var>: holds the data to be signed
</p>
<p><var>signature</var>: will contain newly allocated signature
</p>
<p>This function will sign the given hashed data using a signature algorithm
supported by the private key. Signature algorithms are always used
together with a hash functions.  Different hash functions may be
used for the RSA algorithm, but only SHA-XXX for the DSA keys.
</p>
<p>You may use <code>gnutls_pubkey_get_preferred_hash_algorithm()</code>  to determine
the hash algorithm.
</p>
<p>Note that if <code>GNUTLS_PRIVKEY_SIGN_FLAG_TLS1_RSA</code>  flag is specified this function
will ignore  <code>hash_algo</code> and perform a raw PKCS1 signature.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fprivkey_005fdecrypt_005fdata"></a>Function: <em>int</em> <strong>gnutls_privkey_decrypt_data</strong> <em>(gnutls_privkey_t <var>key</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>ciphertext</var>, gnutls_datum_t * <var>plaintext</var>)</em></dt>
<dd><p><var>key</var>: Holds the key
</p>
<p><var>flags</var>: zero for now
</p>
<p><var>ciphertext</var>: holds the data to be decrypted
</p>
<p><var>plaintext</var>: will contain the decrypted data, allocated with <code>gnutls_malloc()</code> 
</p>
<p>This function will decrypt the given data using the algorithm
supported by the private key.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<p>Signing existing structures, such as certificates, CRLs,
or certificate requests, as well as associating public
keys with structures is also possible using the 
key abstractions.
</p>




<dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fpubkey"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_pubkey</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_pubkey_t <var>key</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>key</var>: holds a public key
</p>
<p>This function will set the public parameters from the given public
key to the request.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fpubkey"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_pubkey</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_pubkey_t <var>key</var>)</em></dt>
<dd><p><var>crt</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>key</var>: holds a public key
</p>
<p>This function will set the public parameters from the given public
key to the request.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fprivkey_005fsign">gnutls_x509_crt_privkey_sign</a> (gnutls_x509_crt_t <var>crt</var>, gnutls_x509_crt_t <var>issuer</var>, gnutls_privkey_t <var>issuer_key</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrl_005fprivkey_005fsign">gnutls_x509_crl_privkey_sign</a> (gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_t <var>issuer</var>, gnutls_privkey_t <var>issuer_key</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrq_005fprivkey_005fsign">gnutls_x509_crq_privkey_sign</a> (gnutls_x509_crq_t <var>crq</var>, gnutls_privkey_t <var>key</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned int <var>flags</var>)</code></dt>
</dl>


<hr>
<a name="Application_002dspecific-keys"></a>
<div class="header">
<p>
Next: <a href="#Smart-cards-and-HSMs" accesskey="n" rel="next">Smart cards and HSMs</a>, Previous: <a href="#Abstract-key-types" accesskey="p" rel="prev">Abstract key types</a>, Up: <a href="#Hardware-security-modules-and-abstract-key-types" accesskey="u" rel="up">Hardware security modules and abstract key types</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="System-and-application_002dspecific-keys"></a>
<h3 class="section">5.2 System and application-specific keys</h3>
<a name="index-Application_002dspecific-keys"></a>
<a name="index-System_002dspecific-keys"></a>

<a name="System_002dspecific-keys"></a>
<h4 class="subsection">5.2.1 System-specific keys</h4>
<p>In several systems there are keystores which allow to read, store and use certificates
and private keys. For these systems GnuTLS provides the system-key API in <code>gnutls/system-keys.h</code>.
That API provides the ability to iterate through all stored keys, add and delete keys as well
as use these keys using a URL which starts with &quot;system:&quot;. The format of the URLs is system-specific.
</p>




<dl>
<dt><a name="index-gnutls_005fsystem_005fkey_005fiter_005fget_005finfo"></a>Function: <em>int</em> <strong>gnutls_system_key_iter_get_info</strong> <em>(gnutls_system_key_iter_t * <var>iter</var>, unsigned <var>cert_type</var>, char ** <var>cert_url</var>, char ** <var>key_url</var>, char ** <var>label</var>, gnutls_datum_t * <var>der</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>iter</var>: an iterator of the system keys (must be set to <code>NULL</code>  initially)
</p>
<p><var>cert_type</var>: A value of gnutls_certificate_type_t which indicates the type of certificate to look for
</p>
<p><var>cert_url</var>: The certificate URL of the pair (may be <code>NULL</code> )
</p>
<p><var>key_url</var>: The key URL of the pair (may be <code>NULL</code> )
</p>
<p><var>label</var>: The friendly name (if any) of the pair (may be <code>NULL</code> )
</p>
<p><var>der</var>: if non-NULL the DER data of the certificate
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will return on each call a certificate
and key pair URLs, as well as a label associated with them,
and the DER-encoded certificate. When the iteration is complete it will
return <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> .
</p>
<p>Typically  <code>cert_type</code> should be <code>GNUTLS_CRT_X509</code> .
</p>
<p>All values set are allocated and must be cleared using <code>gnutls_free()</code> ,
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005fsystem_005fkey_005fiter_005fdeinit">gnutls_system_key_iter_deinit</a> (gnutls_system_key_iter_t <var>iter</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fsystem_005fkey_005fadd_005fx509">gnutls_system_key_add_x509</a> (gnutls_x509_crt_t <var>crt</var>, gnutls_x509_privkey_t <var>privkey</var>, const char * <var>label</var>, char ** <var>cert_url</var>, char ** <var>key_url</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fsystem_005fkey_005fdelete">gnutls_system_key_delete</a> (const char * <var>cert_url</var>, const char * <var>key_url</var>)</code></dt>
</dl>

<a name="Application_002dspecific-keys-1"></a>
<h4 class="subsection">5.2.2 Application-specific keys</h4>
<p>For systems where GnuTLS doesn&rsquo;t provide a system specific store,
it may often be desirable to define a custom class of keys
that are identified via URLs and available to GnuTLS calls such as <a href="#gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile2">gnutls_certificate_set_x509_key_file2</a>.
Such keys can be registered using the API in <code>gnutls/urls.h</code>. The function
which registers such keys is <a href="#gnutls_005fregister_005fcustom_005furl">gnutls_register_custom_url</a>.
</p>




<dl>
<dt><a name="index-gnutls_005fregister_005fcustom_005furl"></a>Function: <em>int</em> <strong>gnutls_register_custom_url</strong> <em>(const gnutls_custom_url_st * <var>st</var>)</em></dt>
<dd><p><var>st</var>: A <code>gnutls_custom_url_st</code>  structure
</p>
<p>Register a custom URL. This will affect the following functions:
<code>gnutls_url_is_supported()</code> , <code>gnutls_privkey_import_url()</code> ,
gnutls_pubkey_import_url, <code>gnutls_x509_crt_import_url()</code>  
and all functions that depend on
them, e.g., <code>gnutls_certificate_set_x509_key_file2()</code> .
</p>
<p>The provided structure and callback functions must be valid throughout
the lifetime of the process. The registration of an existing URL type
will fail with <code>GNUTLS_E_INVALID_REQUEST</code> .
</p>
<p>This function is not thread safe.
</p>
<p><strong>Returns:</strong> returns zero if the given structure was imported or a negative value otherwise.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<p>The input to this function are three callback functions as well as
the prefix of the URL, (e.g., &quot;mypkcs11:&quot;) and the length of the prefix.
The types of the callbacks are shown below, and are expected to
use the exported gnutls functions to import the keys and certificates.
E.g., a typical <code>import_key</code> callback should use <a href="#gnutls_005fprivkey_005fimport_005fext3">gnutls_privkey_import_ext3</a>.
</p>
<div class="example">
<pre class="example">typedef int (*gnutls_privkey_import_url_func)(gnutls_privkey_t pkey,
                                              const char *url,
                                              unsigned flags);

typedef int (*gnutls_x509_crt_import_url_func)(gnutls_x509_crt_t pkey,
                                               const char *url,
                                               unsigned flags);

/* The following callbacks are optional */

/* This is to enable gnutls_pubkey_import_url() */
typedef int (*gnutls_pubkey_import_url_func)(gnutls_pubkey_t pkey,
					     const char *url, unsigned flags);

/* This is to allow constructing a certificate chain. It will be provided
 * the initial certificate URL and the certificate to find its issuer, and must
 * return zero and the DER encoding of the issuer's certificate. If not available,
 * it should return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE. */
typedef int (*gnutls_get_raw_issuer_func)(const char *url, gnutls_x509_crt_t crt,
					  gnutls_datum_t *issuer_der, unsigned flags);

typedef struct custom_url_st {
        const char *name;
        unsigned name_size;
        gnutls_privkey_import_url_func import_key;
        gnutls_x509_crt_import_url_func import_crt;
        gnutls_pubkey_import_url_func import_pubkey;
	gnutls_get_raw_issuer_func get_issuer;
} gnutls_custom_url_st;
</pre></div>



<hr>
<a name="Smart-cards-and-HSMs"></a>
<div class="header">
<p>
Next: <a href="#Trusted-Platform-Module" accesskey="n" rel="next">Trusted Platform Module</a>, Previous: <a href="#Application_002dspecific-keys" accesskey="p" rel="prev">Application-specific keys</a>, Up: <a href="#Hardware-security-modules-and-abstract-key-types" accesskey="u" rel="up">Hardware security modules and abstract key types</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Smart-cards-and-HSMs-1"></a>
<h3 class="section">5.3 Smart cards and HSMs</h3>
<a name="index-PKCS-_002311-tokens"></a>
<a name="index-hardware-tokens"></a>
<a name="index-hardware-security-modules"></a>
<a name="index-smart-cards"></a>

<p>In this section we present the smart-card and hardware security module (HSM) support 
in <acronym>GnuTLS</acronym> using <acronym>PKCS</acronym> #11 [<em>PKCS11</em>]. Hardware security
modules and smart cards provide a way to store private keys and perform
operations on them without exposing them. This decouples cryptographic
keys from the applications that use them and provide an additional 
security layer against cryptographic key extraction.
Since this can also be achieved in software components such as in Gnome keyring,
we will use the term security module to describe any cryptographic key 
separation subsystem.
</p>
<p><acronym>PKCS</acronym> #11 is plugin API allowing applications to access cryptographic
operations on a security module, as well as to objects residing on it. PKCS
#11 modules exist for hardware tokens such as smart cards<a name="DOCF10" href="#FOOT10"><sup>10</sup></a>,
cryptographic tokens, as well as for software modules like <acronym>Gnome Keyring</acronym>. 
The objects residing on a security module may be certificates, public keys, 
private keys or secret keys. Of those certificates and public/private key 
pairs can be used with <acronym>GnuTLS</acronym>. PKCS #11&rsquo;s main advantage is that 
it allows operations on private key objects such as decryption
and signing without exposing the key. In GnuTLS the PKCS #11 functionality is
available in <code>gnutls/pkcs11.h</code>.
</p>
<p>Moreover <acronym>PKCS</acronym> #11 can be (ab)used to allow all applications in the same operating system to access
shared cryptographic keys and certificates in a uniform way, as in <a href="#fig_002dpkcs11_002dvision">Figure 5.1</a>.
That way applications could load their trusted certificate list, as well as user
certificates from a common PKCS #11 module. Such a provider is the p11-kit trust
storage module<a name="DOCF11" href="#FOOT11"><sup>11</sup></a>.
</p>
<div class="float"><a name="fig_002dpkcs11_002dvision"></a>
<img src="pkcs11-vision.png" alt="pkcs11-vision">

<div class="float-caption"><p><strong>Figure 5.1: </strong>PKCS #11 module usage.</p></div></div>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#PKCS11-Initialization" accesskey="1">PKCS11 Initialization</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Accessing-objects-that-require-a-PIN" accesskey="2">Accessing objects that require a PIN</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Reading-objects" accesskey="3">Reading objects</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Writing-objects" accesskey="4">Writing objects</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Using-a-PKCS11-token-with-TLS" accesskey="5">Using a PKCS11 token with TLS</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#p11tool-Invocation" accesskey="6">p11tool Invocation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="PKCS11-Initialization"></a>
<div class="header">
<p>
Next: <a href="#Accessing-objects-that-require-a-PIN" accesskey="n" rel="next">Accessing objects that require a PIN</a>, Up: <a href="#Smart-cards-and-HSMs" accesskey="u" rel="up">Smart cards and HSMs</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Initialization-1"></a>
<h4 class="subsection">5.3.1 Initialization</h4>
<p>To allow all <acronym>GnuTLS</acronym> applications to transparently access smard cards
and tokens, <acronym>PKCS</acronym> #11 is automatically initialized during the first
call of a <acronym>PKCS</acronym> #11 related function. The initialization process, based
on p11-kit configuration, loads any appropriate modules. The p11-kit configuration
files<a name="DOCF12" href="#FOOT12"><sup>12</sup></a> are typically stored in <code>/etc/pkcs11/modules/</code>.
For example a file that will instruct GnuTLS to load the <acronym>OpenSC</acronym> module,
could be named <code>/etc/pkcs11/modules/opensc.module</code> and contain the following:
</p>
<div class="example">
<pre class="example">module: /usr/lib/opensc-pkcs11.so
</pre></div>

<p>If you use these configuration files, then there is no need for other initialization in
<acronym>GnuTLS</acronym>, except for the PIN and token callbacks (see next section).
In several cases, however, it is desirable to limit badly behaving modules
(e.g., modules that add an unacceptable delay on initialization)
to single applications. That can be done using the &ldquo;enable-in:&rdquo; option
followed by the base name of applications that this module should be used.
</p>
<p>It is also possible to manually initialize the PKCS #11 subsystem if the 
default settings are not desirable. To completely disable PKCS #11 support you
need to call <a href="#gnutls_005fpkcs11_005finit">gnutls_pkcs11_init</a> with the flag <code>GNUTLS_PKCS11_FLAG_MANUAL</code>
prior to <a href="#gnutls_005fglobal_005finit">gnutls_global_init</a>.
</p>




<dl>
<dt><a name="index-gnutls_005fpkcs11_005finit"></a>Function: <em>int</em> <strong>gnutls_pkcs11_init</strong> <em>(unsigned int <var>flags</var>, const char * <var>deprecated_config_file</var>)</em></dt>
<dd><p><var>flags</var>: An ORed sequence of <code>GNUTLS_PKCS11_FLAG_</code> *
</p>
<p><var>deprecated_config_file</var>: either NULL or the location of a deprecated
configuration file
</p>
<p>This function will initialize the PKCS 11 subsystem in gnutls. It will
read configuration files if <code>GNUTLS_PKCS11_FLAG_AUTO</code>  is used or allow
you to independently load PKCS 11 modules using <code>gnutls_pkcs11_add_provider()</code> 
if <code>GNUTLS_PKCS11_FLAG_MANUAL</code>  is specified.
</p>
<p>You don&rsquo;t need to call this function since GnuTLS 3.3.0 because it is being called
during the first request PKCS 11 operation. That call will assume the <code>GNUTLS_PKCS11_FLAG_AUTO</code> 
flag. If another flags are required then it must be called independently
prior to any PKCS 11 operation.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<p>Note that, PKCS #11 modules behave in a peculiar way after a fork; they
require a reinitialization of all the used PKCS #11 resources.
While GnuTLS automates that process, there are corner cases where
it is not possible to handle it correctly in an automated way<a name="DOCF13" href="#FOOT13"><sup>13</sup></a>. For that reasons it is
recommended not to mix fork() and PKCS #11 module usage. It is recommended
to initialize and use any PKCS #11 resources in a single process.
</p>
<p>Older versions of <acronym>GnuTLS</acronym> required to call <a href="#gnutls_005fpkcs11_005freinit">gnutls_pkcs11_reinit</a>
after a fork() call; since 3.3.0 this is no longer required.
</p>
<hr>
<a name="Accessing-objects-that-require-a-PIN"></a>
<div class="header">
<p>
Next: <a href="#Reading-objects" accesskey="n" rel="next">Reading objects</a>, Previous: <a href="#PKCS11-Initialization" accesskey="p" rel="prev">PKCS11 Initialization</a>, Up: <a href="#Smart-cards-and-HSMs" accesskey="u" rel="up">Smart cards and HSMs</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Accessing-objects-that-require-a-PIN-1"></a>
<h4 class="subsection">5.3.2 Accessing objects that require a PIN</h4>

<p>Objects stored in token such as a private keys are typically protected
from access by a PIN or password. This PIN may be required to either read
the object (if allowed) or to perform operations with it. To allow obtaining
the PIN when accessing a protected object, as well as probe
the user to insert the token the following functions allow to set a callback.
</p>
<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005fpkcs11_005fset_005ftoken_005ffunction">gnutls_pkcs11_set_token_function</a> (gnutls_pkcs11_token_callback_t <var>fn</var>, void * <var>userdata</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fpkcs11_005fset_005fpin_005ffunction">gnutls_pkcs11_set_pin_function</a> (gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs11_005fadd_005fprovider">gnutls_pkcs11_add_provider</a> (const char * <var>name</var>, const char * <var>params</var>)</code></dt>
<dt><code><var>gnutls_pin_callback_t</var> <a href="#gnutls_005fpkcs11_005fget_005fpin_005ffunction">gnutls_pkcs11_get_pin_function</a> (void ** <var>userdata</var>)</code></dt>
</dl>

<p>The callback is of type <code>gnutls_pin_callback_t</code> and will have as
input the provided userdata, the PIN attempt number, a URL describing the
token, a label describing the object and flags. The PIN must be at most 
of <code>pin_max</code> size and must be copied to pin variable. The function must
return 0 on success or a negative error code otherwise.
</p>
<pre class="verbatim">typedef int (*gnutls_pin_callback_t) (void *userdata, int attempt,
                                      const char *token_url,
                                      const char *token_label,
                                      unsigned int flags,
                                      char *pin, size_t pin_max);
</pre>
<p>The flags are of <code>gnutls_pin_flag_t</code> type and are explained below.
</p>
<div class="float"><a name="gnutls_005fpin_005fflag_005ft"></a>


<dl compact="compact">
<dt><code>GNUTLS_PIN_USER</code></dt>
<dd><p>The PIN for the user.
</p></dd>
<dt><code>GNUTLS_PIN_SO</code></dt>
<dd><p>The PIN for the security officer (admin).
</p></dd>
<dt><code>GNUTLS_PIN_FINAL_TRY</code></dt>
<dd><p>This is the final try before blocking.
</p></dd>
<dt><code>GNUTLS_PIN_COUNT_LOW</code></dt>
<dd><p>Few tries remain before token blocks.
</p></dd>
<dt><code>GNUTLS_PIN_CONTEXT_SPECIFIC</code></dt>
<dd><p>The PIN is for a specific action and key like signing.
</p></dd>
<dt><code>GNUTLS_PIN_WRONG</code></dt>
<dd><p>Last given PIN was not correct.
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 5.2: </strong>The <code>gnutls_pin_flag_t</code> enumeration.</p></div></div>
<p>Note that due to limitations of <acronym>PKCS</acronym> #11 there are issues when multiple libraries 
are sharing a module. To avoid this problem GnuTLS uses <acronym>p11-kit</acronym>
that provides a middleware to control access to resources over the
multiple users.
</p>
<p>To avoid conflicts with multiple registered callbacks for PIN functions,
<a href="#gnutls_005fpkcs11_005fget_005fpin_005ffunction">gnutls_pkcs11_get_pin_function</a> may be used to check for any previously
set functions. In addition context specific PIN functions are allowed, e.g., by
using functions below.
</p>
<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005fcertificate_005fset_005fpin_005ffunction">gnutls_certificate_set_pin_function</a> (gnutls_certificate_credentials_t       <var>cred</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fpubkey_005fset_005fpin_005ffunction">gnutls_pubkey_set_pin_function</a> (gnutls_pubkey_t <var>key</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fprivkey_005fset_005fpin_005ffunction">gnutls_privkey_set_pin_function</a> (gnutls_privkey_t <var>key</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fpkcs11_005fobj_005fset_005fpin_005ffunction">gnutls_pkcs11_obj_set_pin_function</a> (gnutls_pkcs11_obj_t <var>obj</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fx509_005fcrt_005fset_005fpin_005ffunction">gnutls_x509_crt_set_pin_function</a> (gnutls_x509_crt_t <var>crt</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</code></dt>
</dl>

<hr>
<a name="Reading-objects"></a>
<div class="header">
<p>
Next: <a href="#Writing-objects" accesskey="n" rel="next">Writing objects</a>, Previous: <a href="#Accessing-objects-that-require-a-PIN" accesskey="p" rel="prev">Accessing objects that require a PIN</a>, Up: <a href="#Smart-cards-and-HSMs" accesskey="u" rel="up">Smart cards and HSMs</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Reading-objects-1"></a>
<h4 class="subsection">5.3.3 Reading objects</h4>

<p>All <acronym>PKCS</acronym> #11 objects are referenced by <acronym>GnuTLS</acronym> functions by
URLs as described in [<em>PKCS11URI</em>]. 
This allows for a consistent naming of objects across systems and applications
in the same system. For example a public
key on a smart card may be referenced as:
</p>
<div class="example">
<pre class="example">pkcs11:token=Nikos;serial=307521161601031;model=PKCS%2315; \
manufacturer=EnterSafe;object=test1;type=public;\
id=32f153f3e37990b08624141077ca5dec2d15faed
</pre></div>

<p>while the smart card itself can be referenced as:
</p><div class="example">
<pre class="example">pkcs11:token=Nikos;serial=307521161601031;model=PKCS%2315;manufacturer=EnterSafe
</pre></div>

<p>Objects stored in a <acronym>PKCS</acronym> #11 token can be extracted
if they are not marked as sensitive. Usually only private keys are marked as
sensitive and cannot be extracted, while certificates and other data can
be retrieved. The functions that can be used to access objects
are shown below.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpkcs11_005fobj_005fimport_005furl">gnutls_pkcs11_obj_import_url</a> (gnutls_pkcs11_obj_t <var>obj</var>, const char * <var>url</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs11_005fobj_005fexport_005furl">gnutls_pkcs11_obj_export_url</a> (gnutls_pkcs11_obj_t <var>obj</var>, gnutls_pkcs11_url_type_t <var>detailed</var>, char ** <var>url</var>)</code></dt>
</dl>





<dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fget_005finfo"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_get_info</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>, gnutls_pkcs11_obj_info_t <var>itype</var>, void * <var>output</var>, size_t * <var>output_size</var>)</em></dt>
<dd><p><var>obj</var>: should contain a <code>gnutls_pkcs11_obj_t</code>  type
</p>
<p><var>itype</var>: Denotes the type of information requested
</p>
<p><var>output</var>: where output will be stored
</p>
<p><var>output_size</var>: contains the maximum size of the output and will be overwritten with actual
</p>
<p>This function will return information about the PKCS11 certificate
such as the label, id as well as token information where the key is
stored. When output is text it returns null terminated string
although  <code>output_size</code> contains the size of the actual data only.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fimport_005fpkcs11">gnutls_x509_crt_import_pkcs11</a> (gnutls_x509_crt_t <var>crt</var>, gnutls_pkcs11_obj_t <var>pkcs11_crt</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005fimport_005furl">gnutls_x509_crt_import_url</a> (gnutls_x509_crt_t <var>crt</var>, const char * <var>url</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fx509_005fcrt_005flist_005fimport_005fpkcs11">gnutls_x509_crt_list_import_pkcs11</a> (gnutls_x509_crt_t * <var>certs</var>, unsigned int <var>cert_max</var>, gnutls_pkcs11_obj_t * const <var>objs</var>, unsigned int <var>flags</var>)</code></dt>
</dl>

<p>Properties of the physical token can also be accessed and altered with <acronym>GnuTLS</acronym>.
For example data in a token can be erased (initialized), PIN can be altered, etc.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpkcs11_005ftoken_005finit">gnutls_pkcs11_token_init</a> (const char * <var>token_url</var>, const char * <var>so_pin</var>, const char * <var>label</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs11_005ftoken_005fget_005furl">gnutls_pkcs11_token_get_url</a> (unsigned int <var>seq</var>, gnutls_pkcs11_url_type_t <var>detailed</var>, char ** <var>url</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs11_005ftoken_005fget_005finfo">gnutls_pkcs11_token_get_info</a> (const char * <var>url</var>, gnutls_pkcs11_token_info_t <var>ttype</var>, void * <var>output</var>, size_t * <var>output_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs11_005ftoken_005fget_005fflags">gnutls_pkcs11_token_get_flags</a> (const char * <var>url</var>, unsigned int * <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs11_005ftoken_005fset_005fpin">gnutls_pkcs11_token_set_pin</a> (const char * <var>token_url</var>, const char * <var>oldpin</var>, const char * <var>newpin</var>, unsigned int <var>flags</var>)</code></dt>
</dl>

<p>The following examples demonstrate the usage of the API. The first example
will list all available PKCS #11 tokens in a system and the latter will
list all certificates in a token that have a corresponding private key.
</p>
<div class="example">
<pre class="example">int i;
char* url;

gnutls_global_init();

for (i=0;;i++) 
  {
    ret = gnutls_pkcs11_token_get_url(i, &amp;url);
    if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
      break;

    if (ret &lt; 0)
      exit(1);
		
    fprintf(stdout, &quot;Token[%d]: URL: %s\n&quot;, i, url);
    gnutls_free(url);
  }
gnutls_global_deinit();
</pre></div>

<pre class="verbatim">/* This example code is placed in the public domain. */

#include &lt;config.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/pkcs11.h&gt;
#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;

#define URL &quot;pkcs11:URL&quot;

int main(int argc, char **argv)
{
        gnutls_pkcs11_obj_t *obj_list;
        gnutls_x509_crt_t xcrt;
        unsigned int obj_list_size = 0;
        gnutls_datum_t cinfo;
        int ret;
        unsigned int i;

        ret = gnutls_pkcs11_obj_list_import_url4(&amp;obj_list, &amp;obj_list_size, URL,
                                                GNUTLS_PKCS11_OBJ_FLAG_CRT|
                                                GNUTLS_PKCS11_OBJ_FLAG_WITH_PRIVKEY);
        if (ret &lt; 0)
                return -1;

        /* now all certificates are in obj_list */
        for (i = 0; i &lt; obj_list_size; i++) {

                gnutls_x509_crt_init(&amp;xcrt);

                gnutls_x509_crt_import_pkcs11(xcrt, obj_list[i]);

                gnutls_x509_crt_print(xcrt, GNUTLS_CRT_PRINT_FULL, &amp;cinfo);

                fprintf(stdout, &quot;cert[%d]:\n %s\n\n&quot;, i, cinfo.data);

                gnutls_free(cinfo.data);
                gnutls_x509_crt_deinit(xcrt);
        }

        for (i = 0; i &lt; obj_list_size; i++)
        	gnutls_pkcs11_obj_deinit(obj_list[i]);
	gnutls_free(obj_list);

        return 0;
}
</pre>
<hr>
<a name="Writing-objects"></a>
<div class="header">
<p>
Next: <a href="#Using-a-PKCS11-token-with-TLS" accesskey="n" rel="next">Using a PKCS11 token with TLS</a>, Previous: <a href="#Reading-objects" accesskey="p" rel="prev">Reading objects</a>, Up: <a href="#Smart-cards-and-HSMs" accesskey="u" rel="up">Smart cards and HSMs</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Writing-objects-1"></a>
<h4 class="subsection">5.3.4 Writing objects</h4>

<p>With <acronym>GnuTLS</acronym> you can copy existing private keys and certificates
to a token. Note that when copying private keys it is recommended to mark
them as sensitive using the <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_SENSITIVE</code>
to prevent its extraction. An object can be marked as private using the flag 
<code>GNUTLS_PKCS11_OBJ_FLAG_MARK_PRIVATE</code>, to require PIN to be
entered before accessing the object (for operations or otherwise).
</p>




<dl>
<dt><a name="index-gnutls_005fpkcs11_005fcopy_005fx509_005fprivkey2"></a>Function: <em>int</em> <strong>gnutls_pkcs11_copy_x509_privkey2</strong> <em>(const char * <var>token_url</var>, gnutls_x509_privkey_t <var>key</var>, const char * <var>label</var>, const gnutls_datum_t * <var>cid</var>, unsigned int <var>key_usage</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>token_url</var>: A PKCS <code>11</code>  URL specifying a token
</p>
<p><var>key</var>: A private key
</p>
<p><var>label</var>: A name to be used for the stored data
</p>
<p><var>cid</var>: The CKA_ID to set for the object -if NULL, the ID will be derived from the public key
</p>
<p><var>key_usage</var>: One of GNUTLS_KEY_*
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_* flags
</p>
<p>This function will copy a private key into a PKCS <code>11</code>  token specified by
a URL. It is highly recommended flags to contain <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_SENSITIVE</code> 
unless there is a strong reason not to.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>





<dl>
<dt><a name="index-gnutls_005fpkcs11_005fcopy_005fx509_005fcrt2"></a>Function: <em>int</em> <strong>gnutls_pkcs11_copy_x509_crt2</strong> <em>(const char * <var>token_url</var>, gnutls_x509_crt_t <var>crt</var>, const char * <var>label</var>, const gnutls_datum_t * <var>cid</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>token_url</var>: A PKCS <code>11</code>  URL specifying a token
</p>
<p><var>crt</var>: The certificate to copy
</p>
<p><var>label</var>: The name to be used for the stored data
</p>
<p><var>cid</var>: The CKA_ID to set for the object -if NULL, the ID will be derived from the public key
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_FLAG_*
</p>
<p>This function will copy a certificate into a PKCS <code>11</code>  token specified by
a URL. Valid flags to mark the certificate: <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_TRUSTED</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_MARK_SENSITIVE</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_PRIVATE</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_MARK_CA</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_ALWAYS_AUTH</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fpkcs11_005fdelete_005furl"></a>Function: <em>int</em> <strong>gnutls_pkcs11_delete_url</strong> <em>(const char * <var>object_url</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>object_url</var>: The URL of the object to delete.
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_* flags
</p>
<p>This function will delete objects matching the given URL.
Note that not all tokens support the delete operation.
</p>
<p><strong>Returns:</strong> On success, the number of objects deleted is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>


<hr>
<a name="Using-a-PKCS11-token-with-TLS"></a>
<div class="header">
<p>
Next: <a href="#p11tool-Invocation" accesskey="n" rel="next">p11tool Invocation</a>, Previous: <a href="#Writing-objects" accesskey="p" rel="prev">Writing objects</a>, Up: <a href="#Smart-cards-and-HSMs" accesskey="u" rel="up">Smart cards and HSMs</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Using-a-PKCS-_002311-token-with-TLS"></a>
<h4 class="subsection">5.3.5 Using a <acronym>PKCS</acronym> #11 token with TLS</h4>

<p>It is possible to use a <acronym>PKCS</acronym> #11 token to a TLS
session, as shown in <a href="#ex_002dpkcs11_002dclient">ex-pkcs11-client</a>. In addition
the following functions can be used to load PKCS #11 key and
certificates by specifying a PKCS #11 URL instead of a filename.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fx509_005ftrust_005ffile">gnutls_certificate_set_x509_trust_file</a> (gnutls_certificate_credentials_t            <var>cred</var>, const char * <var>cafile</var>, gnutls_x509_crt_fmt_t <var>type</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile2">gnutls_certificate_set_x509_key_file2</a> (gnutls_certificate_credentials_t <var>res</var>, const char * <var>certfile</var>, const char * <var>keyfile</var>, gnutls_x509_crt_fmt_t <var>type</var>, const char * <var>pass</var>, unsigned int <var>flags</var>)</code></dt>
</dl>




<dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005fsystem_005ftrust"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_system_trust</strong> <em>(gnutls_certificate_credentials_t       <var>cred</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p>This function adds the system&rsquo;s default trusted CAs in order to
verify client or server certificates.
</p>
<p>In the case the system is currently unsupported <code>GNUTLS_E_UNIMPLEMENTED_FEATURE</code> 
is returned.
</p>
<p><strong>Returns:</strong> the number of certificates processed or a negative error code
on error.
</p>
<p><strong>Since:</strong> 3.0.20
</p></dd></dl>

<hr>
<a name="p11tool-Invocation"></a>
<div class="header">
<p>
Previous: <a href="#Using-a-PKCS11-token-with-TLS" accesskey="p" rel="prev">Using a PKCS11 token with TLS</a>, Up: <a href="#Smart-cards-and-HSMs" accesskey="u" rel="up">Smart cards and HSMs</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Invoking-p11tool"></a>
<h4 class="subsection">5.3.6 Invoking p11tool</h4>
<a name="index-p11tool"></a>


<p>Program that allows operations on PKCS #11 smart cards
and security modules. 
</p>
<p>To use PKCS #11 tokens with GnuTLS the p11-kit configuration files need to be setup.
That is create a .module file in /etc/pkcs11/modules with the contents &rsquo;module: /path/to/pkcs11.so&rsquo;.
Alternatively the configuration file /etc/gnutls/pkcs11.conf has to exist and contain a number
of lines of the form &rsquo;load=/usr/lib/opensc-pkcs11.so&rsquo;.
</p>
<p>You can provide the PIN to be used for the PKCS #11 operations with the environment variables
GNUTLS_PIN and GNUTLS_SO_PIN.
</p>

<p>This section was generated by <strong>AutoGen</strong>,
using the <code>agtexi-cmd</code> template and the option descriptions for the <code>p11tool</code> program.
This software is released under the GNU General Public License, version 3 or later.
</p>

<a name="p11tool-usage"></a><a name="p11tool-help_002fusage-_0028_002d_002dhelp_0029"></a>
<h4 class="subsection">5.3.7 p11tool help/usage (<samp>--help</samp>)</h4>
<a name="index-p11tool-help"></a>

<p>This is the automatically generated usage text for p11tool.
</p>
<p>The text printed is the same whether selected with the <code>help</code> option
(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>).  <code>more-help</code> will print
the usage text by passing it through a pager program.
<code>more-help</code> is disabled on platforms without a working
<code>fork(2)</code> function.  The <code>PAGER</code> environment variable is
used to select the program, defaulting to <samp>more</samp>.  Both will exit
with a status code of 0.
</p>
<div class="example">
<pre class="example">p11tool - GnuTLS PKCS #11 tool
Usage:  p11tool [ -&lt;flag&gt; [&lt;val&gt;] | --&lt;name&gt;[{=| }&lt;val&gt;] ]... [url]


Tokens:

       --list-tokens          List all available tokens
       --list-token-urls      List the URLs available tokens
       --list-mechanisms      List all available mechanisms in a token
       --initialize           Initializes a PKCS #11 token
       --set-pin=str          Specify the PIN to use on token initialization
       --set-so-pin=str       Specify the Security Officer's PIN to use on token initialization

Object listing:

       --list-all             List all available objects in a token
       --list-all-certs       List all available certificates in a token
       --list-certs           List all certificates that have an associated private key
       --list-all-privkeys    List all available private keys in a token
       --list-privkeys        an alias for the 'list-all-privkeys' option
       --list-keys            an alias for the 'list-all-privkeys' option
       --list-all-trusted     List all available certificates marked as trusted
       --export               Export the object specified by the URL
       --export-chain         Export the certificate specified by the URL and its chain of trust
       --export-pubkey        Export the public key for a private key
       --info                 List information on an available object in a token

Key generation:

       --generate-rsa         Generate an RSA private-public key pair
       --generate-dsa         Generate a DSA private-public key pair
       --generate-ecc         Generate an ECDSA private-public key pair
       --bits=num             Specify the number of bits for key generate
       --curve=str            Specify the curve used for EC key generation
       --sec-param=str        Specify the security level

Writing objects:

       --set-id=str           Set the CKA_ID (in hex) for the specified by the URL object
                                - prohibits the option 'write'
       --set-label=str        Set the CKA_LABEL for the specified by the URL object
                                - prohibits these options:
                                write
                                set-id
       --write                Writes the loaded objects to a PKCS #11 token
       --delete               Deletes the objects matching the given PKCS #11 URL
       --label=str            Sets a label for the write operation
       --id=str               Sets an ID for the write operation
       --mark-wrap            Marks the generated key to be a wrapping key
                                - disabled as '--no-mark-wrap'
       --mark-trusted         Marks the object to be written as trusted
                                - disabled as '--no-mark-trusted'
       --mark-decrypt         Marks the object to be written for decryption
                                - disabled as '--no-mark-decrypt'
   -!, --mark-sign            Marks the object to be written for signature generation
                                - disabled as '--no-mark-sign'
   -&quot;, --mark-ca              Marks the object to be written as a CA
                                - disabled as '--no-mark-ca'
   -#, --mark-private         Marks the object to be written as private
                                - disabled as '--no-mark-private'
                                - enabled by default
   -$, --trusted              an alias for the 'mark-trusted' option
   -%, --ca                   an alias for the 'mark-ca' option
   -&amp;, --private              an alias for the 'mark-private' option
                                - enabled by default
   -', --secret-key=str       Provide a hex encoded secret key
   -(, --load-privkey=file    Private key file to use
                                - file must pre-exist
   -), --load-pubkey=file     Public key file to use
                                - file must pre-exist
   -*, --load-certificate=file Certificate file to use
                                - file must pre-exist

Other options:

   -d, --debug=num            Enable debugging
                                - it must be in the range:
                                  0 to 9999
   -+, --outfile=str          Output file
   -,, --login                Force (user) login to token
                                - disabled as '--no-login'
   --, --so-login             Force security officer login to token
                                - disabled as '--no-so-login'
   -., --admin-login          an alias for the 'so-login' option
   -/, --test-sign            Tests the signature operation of the provided object
   -0, --generate-random=num  Generate random data
   -8, --pkcs8                Use PKCS #8 format for private keys
   -1, --inder                Use DER/RAW format for input
                                - disabled as '--no-inder'
   -2, --inraw                an alias for the 'inder' option
   -3, --outder               Use DER format for output certificates, private keys, and DH parameters
                                - disabled as '--no-outder'
   -4, --outraw               an alias for the 'outder' option
   -5, --provider=file        Specify the PKCS #11 provider library
                                - file must pre-exist
   -6, --detailed-url         Print detailed URLs
                                - disabled as '--no-detailed-url'
   -7, --only-urls            Print a compact listing using only the URLs
   -8, --batch                Disable all interaction with the tool

Version, usage and configuration options:

   -v, --version[=arg]        output version information and exit
   -h, --help                 display extended usage information and exit
   -!, --more-help            extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.
Operands and options may be intermixed.  They will be reordered.

Program that allows operations on PKCS #11 smart cards and security
modules.

To use PKCS #11 tokens with GnuTLS the p11-kit configuration files need to
be setup.  That is create a .module file in /etc/pkcs11/modules with the
contents 'module: /path/to/pkcs11.so'.  Alternatively the configuration
file /etc/gnutls/pkcs11.conf has to exist and contain a number of lines of
the form 'load=/usr/lib/opensc-pkcs11.so'.

You can provide the PIN to be used for the PKCS #11 operations with the
environment variables GNUTLS_PIN and GNUTLS_SO_PIN.

</pre></div>

<a name="p11tool-token_002drelated_002doptions"></a><a name="token_002drelated_002doptions-options"></a>
<h4 class="subsection">5.3.8 token-related-options options</h4>
<p>Tokens.
</p><a name="list_002dtoken_002durls-option_002e"></a>
<h4 class="subsubheading">list-token-urls option.</h4>
<a name="p11tool-list_002dtoken_002durls"></a>
<p>This is the &ldquo;list the urls available tokens&rdquo; option.
This is a more compact version of &ndash;list-tokens.
</p><a name="set_002dpin-option_002e"></a>
<h4 class="subsubheading">set-pin option.</h4>
<a name="p11tool-set_002dpin"></a>
<p>This is the &ldquo;specify the pin to use on token initialization&rdquo; option.
This option takes a string argument.
Alternatively the GNUTLS_PIN environment variable may be used.
</p><a name="set_002dso_002dpin-option_002e"></a>
<h4 class="subsubheading">set-so-pin option.</h4>
<a name="p11tool-set_002dso_002dpin"></a>
<p>This is the &ldquo;specify the security officer&rsquo;s pin to use on token initialization&rdquo; option.
This option takes a string argument.
Alternatively the GNUTLS_SO_PIN environment variable may be used.
<a name="p11tool-object_002dlist_002drelated_002doptions"></a></p><a name="object_002dlist_002drelated_002doptions-options"></a>
<h4 class="subsection">5.3.9 object-list-related-options options</h4>
<p>Object listing.
</p><a name="list_002dall_002dprivkeys-option_002e"></a>
<h4 class="subsubheading">list-all-privkeys option.</h4>
<a name="p11tool-list_002dall_002dprivkeys"></a>
<p>This is the &ldquo;list all available private keys in a token&rdquo; option.
Lists all the private keys in a token that match the specified URL.
</p><a name="list_002dprivkeys-option_002e"></a>
<h4 class="subsubheading">list-privkeys option.</h4>
<a name="p11tool-list_002dprivkeys"></a>
<p>This is an alias for the <code>list-all-privkeys</code> option,
see <a href="#p11tool-list_002dall_002dprivkeys">the list-all-privkeys option documentation</a>.
</p>
<a name="list_002dkeys-option_002e"></a>
<h4 class="subsubheading">list-keys option.</h4>
<a name="p11tool-list_002dkeys"></a>
<p>This is an alias for the <code>list-all-privkeys</code> option,
see <a href="#p11tool-list_002dall_002dprivkeys">the list-all-privkeys option documentation</a>.
</p>
<a name="export_002dchain-option_002e"></a>
<h4 class="subsubheading">export-chain option.</h4>
<a name="p11tool-export_002dchain"></a>
<p>This is the &ldquo;export the certificate specified by the url and its chain of trust&rdquo; option.
Exports the certificate specified by the URL and generates its chain of trust based on the stored certificates in the module.
</p><a name="export_002dpubkey-option_002e"></a>
<h4 class="subsubheading">export-pubkey option.</h4>
<a name="p11tool-export_002dpubkey"></a>
<p>This is the &ldquo;export the public key for a private key&rdquo; option.
Exports the public key for the specified private key
<a name="p11tool-keygen_002drelated_002doptions"></a></p><a name="keygen_002drelated_002doptions-options"></a>
<h4 class="subsection">5.3.10 keygen-related-options options</h4>
<p>Key generation.
</p><a name="generate_002drsa-option_002e"></a>
<h4 class="subsubheading">generate-rsa option.</h4>
<a name="p11tool-generate_002drsa"></a>
<p>This is the &ldquo;generate an rsa private-public key pair&rdquo; option.
Generates an RSA private-public key pair on the specified token.
</p><a name="generate_002ddsa-option_002e"></a>
<h4 class="subsubheading">generate-dsa option.</h4>
<a name="p11tool-generate_002ddsa"></a>
<p>This is the &ldquo;generate a dsa private-public key pair&rdquo; option.
Generates a DSA private-public key pair on the specified token.
</p><a name="generate_002decc-option_002e"></a>
<h4 class="subsubheading">generate-ecc option.</h4>
<a name="p11tool-generate_002decc"></a>
<p>This is the &ldquo;generate an ecdsa private-public key pair&rdquo; option.
Generates an ECDSA private-public key pair on the specified token.
</p><a name="curve-option_002e"></a>
<h4 class="subsubheading">curve option.</h4>
<a name="p11tool-curve"></a>
<p>This is the &ldquo;specify the curve used for ec key generation&rdquo; option.
This option takes a string argument.
Supported values are secp192r1, secp224r1, secp256r1, secp384r1 and secp521r1.
</p><a name="sec_002dparam-option_002e"></a>
<h4 class="subsubheading">sec-param option.</h4>
<a name="p11tool-sec_002dparam"></a>
<p>This is the &ldquo;specify the security level&rdquo; option.
This option takes a string argument <samp>Security parameter</samp>.
This is alternative to the bits option. Available options are [low, legacy, medium, high, ultra].
<a name="p11tool-write_002dobject_002drelated_002doptions"></a></p><a name="write_002dobject_002drelated_002doptions-options"></a>
<h4 class="subsection">5.3.11 write-object-related-options options</h4>
<p>Writing objects.
</p><a name="set_002did-option_002e"></a>
<h4 class="subsubheading">set-id option.</h4>
<a name="p11tool-set_002did"></a>
<p>This is the &ldquo;set the cka_id (in hex) for the specified by the url object&rdquo; option.
This option takes a string argument.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> must not appear in combination with any of the following options:
write.
</li></ul>

<p>Modifies or sets the CKA_ID in the specified by the URL object. The ID should be specified in hexadecimal format without a &rsquo;0x&rsquo; prefix.
</p><a name="set_002dlabel-option_002e"></a>
<h4 class="subsubheading">set-label option.</h4>
<a name="p11tool-set_002dlabel"></a>
<p>This is the &ldquo;set the cka_label for the specified by the url object&rdquo; option.
This option takes a string argument.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> must not appear in combination with any of the following options:
write, set-id.
</li></ul>

<p>Modifies or sets the CKA_LABEL in the specified by the URL object
</p><a name="write-option_002e"></a>
<h4 class="subsubheading">write option.</h4>
<a name="p11tool-write"></a>
<p>This is the &ldquo;writes the loaded objects to a pkcs #11 token&rdquo; option.
It can be used to write private keys, certificates or secret keys to a token. Must be combined with a &ndash;load option.
</p><a name="id-option_002e"></a>
<h4 class="subsubheading">id option.</h4>
<a name="p11tool-id"></a>
<p>This is the &ldquo;sets an id for the write operation&rdquo; option.
This option takes a string argument.
Sets the CKA_ID to be set by the write operation. The ID should be specified in hexadecimal format without a &rsquo;0x&rsquo; prefix.
</p><a name="mark_002dwrap-option_002e"></a>
<h4 class="subsubheading">mark-wrap option.</h4>
<a name="p11tool-mark_002dwrap"></a>
<p>This is the &ldquo;marks the generated key to be a wrapping key&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-mark-wrap.
</li></ul>

<p>Marks the generated key with the CKA_WRAP flag.
</p><a name="mark_002dtrusted-option_002e"></a>
<h4 class="subsubheading">mark-trusted option.</h4>
<a name="p11tool-mark_002dtrusted"></a>
<p>This is the &ldquo;marks the object to be written as trusted&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-mark-trusted.
</li></ul>

<p>Marks the object to be generated/written with the CKA_TRUST flag.
</p><a name="mark_002ddecrypt-option_002e"></a>
<h4 class="subsubheading">mark-decrypt option.</h4>
<a name="p11tool-mark_002ddecrypt"></a>
<p>This is the &ldquo;marks the object to be written for decryption&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-mark-decrypt.
</li></ul>

<p>Marks the object to be generated/written with the CKA_DECRYPT flag set to true.
</p><a name="mark_002dsign-option_002e"></a>
<h4 class="subsubheading">mark-sign option.</h4>
<a name="p11tool-mark_002dsign"></a>
<p>This is the &ldquo;marks the object to be written for signature generation&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-mark-sign.
</li></ul>

<p>Marks the object to be generated/written with the CKA_SIGN flag set to true.
</p><a name="mark_002dca-option_002e"></a>
<h4 class="subsubheading">mark-ca option.</h4>
<a name="p11tool-mark_002dca"></a>
<p>This is the &ldquo;marks the object to be written as a ca&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-mark-ca.
</li></ul>

<p>Marks the object to be generated/written with the CKA_CERTIFICATE_CATEGORY as CA.
</p><a name="mark_002dprivate-option_002e"></a>
<h4 class="subsubheading">mark-private option.</h4>
<a name="p11tool-mark_002dprivate"></a>
<p>This is the &ldquo;marks the object to be written as private&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-mark-private.
</li><li> It is enabled by default.
</li></ul>

<p>Marks the object to be generated/written with the CKA_PRIVATE flag. The written object will require a PIN to be used.
</p><a name="trusted-option_002e"></a>
<h4 class="subsubheading">trusted option.</h4>
<a name="p11tool-trusted"></a>
<p>This is an alias for the <code>mark-trusted</code> option,
see <a href="#p11tool-mark_002dtrusted">the mark-trusted option documentation</a>.
</p>
<a name="ca-option_002e"></a>
<h4 class="subsubheading">ca option.</h4>
<a name="p11tool-ca"></a>
<p>This is an alias for the <code>mark-ca</code> option,
see <a href="#p11tool-mark_002dca">the mark-ca option documentation</a>.
</p>
<a name="private-option_002e"></a>
<h4 class="subsubheading">private option.</h4>
<a name="p11tool-private"></a>
<p>This is an alias for the <code>mark-private</code> option,
see <a href="#p11tool-mark_002dprivate">the mark-private option documentation</a>.
</p>
<a name="secret_002dkey-option_002e"></a>
<h4 class="subsubheading">secret-key option.</h4>
<a name="p11tool-secret_002dkey"></a>
<p>This is the &ldquo;provide a hex encoded secret key&rdquo; option.
This option takes a string argument.
This secret key will be written to the module if &ndash;write is specified.
<a name="p11tool-other_002doptions"></a></p><a name="other_002doptions-options"></a>
<h4 class="subsection">5.3.12 other-options options</h4>
<p>Other options.
</p><a name="debug-option-_0028_002dd_0029_002e"></a>
<h4 class="subsubheading">debug option (-d).</h4>
<a name="p11tool-debug"></a>
<p>This is the &ldquo;enable debugging&rdquo; option.
This option takes a number argument.
Specifies the debug level.
</p><a name="so_002dlogin-option_002e"></a>
<h4 class="subsubheading">so-login option.</h4>
<a name="p11tool-so_002dlogin"></a>
<p>This is the &ldquo;force security officer login to token&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-so-login.
</li></ul>

<p>Forces login to the token as security officer (admin).
</p><a name="admin_002dlogin-option_002e"></a>
<h4 class="subsubheading">admin-login option.</h4>
<a name="p11tool-admin_002dlogin"></a>
<p>This is an alias for the <code>so-login</code> option,
see <a href="#p11tool-so_002dlogin">the so-login option documentation</a>.
</p>
<a name="test_002dsign-option_002e"></a>
<h4 class="subsubheading">test-sign option.</h4>
<a name="p11tool-test_002dsign"></a>
<p>This is the &ldquo;tests the signature operation of the provided object&rdquo; option.
It can be used to test the correct operation of the signature operation.
If both a private and a public key are available this operation will sign and verify
the signed data.
</p><a name="generate_002drandom-option_002e"></a>
<h4 class="subsubheading">generate-random option.</h4>
<a name="p11tool-generate_002drandom"></a>
<p>This is the &ldquo;generate random data&rdquo; option.
This option takes a number argument.
Asks the token to generate a number of bytes of random bytes.
</p><a name="inder-option_002e"></a>
<h4 class="subsubheading">inder option.</h4>
<a name="p11tool-inder"></a>
<p>This is the &ldquo;use der/raw format for input&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-inder.
</li></ul>

<p>Use DER/RAW format for input certificates and private keys.
</p><a name="inraw-option_002e"></a>
<h4 class="subsubheading">inraw option.</h4>
<a name="p11tool-inraw"></a>
<p>This is an alias for the <code>inder</code> option,
see <a href="#p11tool-inder">the inder option documentation</a>.
</p>
<a name="outder-option_002e"></a>
<h4 class="subsubheading">outder option.</h4>
<a name="p11tool-outder"></a>
<p>This is the &ldquo;use der format for output certificates, private keys, and dh parameters&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-outder.
</li></ul>

<p>The output will be in DER or RAW format.
</p><a name="outraw-option_002e"></a>
<h4 class="subsubheading">outraw option.</h4>
<a name="p11tool-outraw"></a>
<p>This is an alias for the <code>outder</code> option,
see <a href="#p11tool-outder">the outder option documentation</a>.
</p>
<a name="provider-option_002e"></a>
<h4 class="subsubheading">provider option.</h4>
<a name="p11tool-provider"></a>
<p>This is the &ldquo;specify the pkcs #11 provider library&rdquo; option.
This option takes a file argument.
This will override the default options in /etc/gnutls/pkcs11.conf
</p><a name="batch-option_002e"></a>
<h4 class="subsubheading">batch option.</h4>
<a name="p11tool-batch"></a>
<p>This is the &ldquo;disable all interaction with the tool&rdquo; option.
In batch mode there will be no prompts, all parameters need to be specified on command line.
<a name="p11tool-exit-status"></a></p><a name="p11tool-exit-status-1"></a>
<h4 class="subsection">5.3.13 p11tool exit status</h4>

<p>One of the following exit values will be returned:
</p><dl compact="compact">
<dt>&lsquo;<samp>0 (EXIT_SUCCESS)</samp>&rsquo;</dt>
<dd><p>Successful program execution.
</p></dd>
<dt>&lsquo;<samp>1 (EXIT_FAILURE)</samp>&rsquo;</dt>
<dd><p>The operation failed or the command syntax was not valid.
</p></dd>
</dl>
<a name="p11tool-See-Also"></a><a name="p11tool-See-Also-1"></a>
<h4 class="subsection">5.3.14 p11tool See Also</h4>
<p>certtool (1)
<a name="p11tool-Examples"></a></p><a name="p11tool-Examples-1"></a>
<h4 class="subsection">5.3.15 p11tool Examples</h4>
<p>To view all tokens in your system use:
</p><div class="example">
<pre class="example">$ p11tool --list-tokens
</pre></div>

<p>To view all objects in a token use:
</p><div class="example">
<pre class="example">$ p11tool --login --list-all &quot;pkcs11:TOKEN-URL&quot;
</pre></div>

<p>To store a private key and a certificate in a token run:
</p><div class="example">
<pre class="example">$ p11tool --login --write &quot;pkcs11:URL&quot; --load-privkey key.pem \
          --label &quot;Mykey&quot;
$ p11tool --login --write &quot;pkcs11:URL&quot; --load-certificate cert.pem \
          --label &quot;Mykey&quot;
</pre></div>
<p>Note that some tokens require the same label to be used for the certificate
and its corresponding private key.
</p>
<p>To generate an RSA private key inside the token use:
</p><div class="example">
<pre class="example">$ p11tool --login --generate-rsa --bits 1024 --label &quot;MyNewKey&quot; \
          --outfile MyNewKey.pub &quot;pkcs11:TOKEN-URL&quot;
</pre></div>
<p>The bits parameter in the above example is explicitly set because some
tokens only support limited choices in the bit length. The output file is the
corresponding public key. This key can be used to general a certificate
request with certtool.
</p><div class="example">
<pre class="example">certtool --generate-request --load-privkey &quot;pkcs11:KEY-URL&quot; \
   --load-pubkey MyNewKey.pub --outfile request.pem
</pre></div>

<hr>
<a name="Trusted-Platform-Module"></a>
<div class="header">
<p>
Previous: <a href="#Smart-cards-and-HSMs" accesskey="p" rel="prev">Smart cards and HSMs</a>, Up: <a href="#Hardware-security-modules-and-abstract-key-types" accesskey="u" rel="up">Hardware security modules and abstract key types</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Trusted-Platform-Module-_0028TPM_0029"></a>
<h3 class="section">5.4 Trusted Platform Module (TPM)</h3>
<a name="index-trusted-platform-module"></a>
<a name="index-TPM"></a>

<p>In this section we present the Trusted Platform Module (TPM) support 
in <acronym>GnuTLS</acronym>. 
</p>
<p>There was a big hype when the TPM chip was introduced into 
computers. Briefly it is a co-processor in your PC that allows it to perform 
calculations independently of the main processor. This has good and bad 
side-effects. In this section we focus on the good ones; these are the fact that 
you can use the TPM chip to perform cryptographic operations on keys stored in it, without 
accessing them. That is very similar to the operation of a <acronym>PKCS</acronym> #11 smart card. 
The chip allows for storage and usage of RSA keys, but has quite some 
operational differences from <acronym>PKCS</acronym> #11 module, and thus require different handling. 
The basic TPM operations supported and used by GnuTLS, are key generation and signing. 
</p>
<p>The next sections assume that the TPM chip in the system is already initialized and
in a operational state.
</p>
<p>In GnuTLS the TPM functionality is available in <code>gnutls/tpm.h</code>.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Keys-in-TPM" accesskey="1">Keys in TPM</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Key-generation" accesskey="2">Key generation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Using-keys" accesskey="3">Using keys</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#tpmtool-Invocation" accesskey="4">tpmtool Invocation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Keys-in-TPM"></a>
<div class="header">
<p>
Next: <a href="#Key-generation" accesskey="n" rel="next">Key generation</a>, Up: <a href="#Trusted-Platform-Module" accesskey="u" rel="up">Trusted Platform Module</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Keys-in-TPM-1"></a>
<h4 class="subsection">5.4.1 Keys in TPM</h4>

<p>The RSA keys in the TPM module may either be stored in a flash memory
within TPM or stored in a file in disk. In the former case the key can
provide operations as with <acronym>PKCS</acronym> #11 and is identified by
a URL. The URL is described in [<em>TPMURI</em>] and is of the following form.
</p><pre class="verbatim">tpmkey:uuid=42309df8-d101-11e1-a89a-97bb33c23ad1;storage=user
</pre>
<p>It consists from a unique identifier of the key as well as the part of the
flash memory the key is stored at. The two options for the storage field are
&lsquo;user&rsquo; and &lsquo;system&rsquo;. The user keys are typically only available to the generating
user and the system keys to all users. The stored in TPM keys are called
registered keys.
</p>
<p>The keys that are stored in the disk are exported from the TPM but in an
encrypted form. To access them two passwords are required. The first is the TPM
Storage Root Key (SRK), and the other is a key-specific password. Also those keys are
identified by a URL of the form:
</p><pre class="verbatim">tpmkey:file=/path/to/file
</pre>
<p>When objects require a PIN to be accessed the same callbacks as with PKCS #11
objects are expected (see <a href="#Accessing-objects-that-require-a-PIN">Accessing objects that require a PIN</a>). Note
that the PIN function may be called multiple times to unlock the SRK and
the specific key in use. The label in the key function will then be set to
&lsquo;SRK&rsquo; when unlocking the SRK key, or to &lsquo;TPM&rsquo; when unlocking any other key.
</p>
<hr>
<a name="Key-generation"></a>
<div class="header">
<p>
Next: <a href="#Using-keys" accesskey="n" rel="next">Using keys</a>, Previous: <a href="#Keys-in-TPM" accesskey="p" rel="prev">Keys in TPM</a>, Up: <a href="#Trusted-Platform-Module" accesskey="u" rel="up">Trusted Platform Module</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Key-generation-1"></a>
<h4 class="subsection">5.4.2 Key generation</h4>

<p>All keys used by the TPM must be generated by the TPM. This can be
done using <a href="#gnutls_005ftpm_005fprivkey_005fgenerate">gnutls_tpm_privkey_generate</a>.
</p>




<dl>
<dt><a name="index-gnutls_005ftpm_005fprivkey_005fgenerate"></a>Function: <em>int</em> <strong>gnutls_tpm_privkey_generate</strong> <em>(gnutls_pk_algorithm_t <var>pk</var>, unsigned int <var>bits</var>, const char * <var>srk_password</var>, const char * <var>key_password</var>, gnutls_tpmkey_fmt_t <var>format</var>, gnutls_x509_crt_fmt_t <var>pub_format</var>, gnutls_datum_t * <var>privkey</var>, gnutls_datum_t * <var>pubkey</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pk</var>: the public key algorithm
</p>
<p><var>bits</var>: the security bits
</p>
<p><var>srk_password</var>: a password to protect the exported key (optional)
</p>
<p><var>key_password</var>: the password for the TPM (optional)
</p>
<p><var>format</var>: the format of the private key
</p>
<p><var>pub_format</var>: the format of the public key
</p>
<p><var>privkey</var>: the generated key
</p>
<p><var>pubkey</var>: the corresponding public key (may be null)
</p>
<p><var>flags</var>: should be a list of GNUTLS_TPM_* flags
</p>
<p>This function will generate a private key in the TPM
chip. The private key will be generated within the chip
and will be exported in a wrapped with TPM&rsquo;s master key
form. Furthermore the wrapped key can be protected with
the provided  <code>password</code> .
</p>
<p>Note that bits in TPM is quantized value. If the input value
is not one of the allowed values, then it will be quantized to
one of 512, 1024, 2048, 4096, 8192 and 16384.
</p>
<p>Allowed flags are:
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005ftpm_005fget_005fregistered">gnutls_tpm_get_registered</a> (gnutls_tpm_key_list_t * <var>list</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005ftpm_005fkey_005flist_005fdeinit">gnutls_tpm_key_list_deinit</a> (gnutls_tpm_key_list_t <var>list</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005ftpm_005fkey_005flist_005fget_005furl">gnutls_tpm_key_list_get_url</a> (gnutls_tpm_key_list_t <var>list</var>, unsigned int <var>idx</var>, char ** <var>url</var>, unsigned int <var>flags</var>)</code></dt>
</dl>





<dl>
<dt><a name="index-gnutls_005ftpm_005fprivkey_005fdelete"></a>Function: <em>int</em> <strong>gnutls_tpm_privkey_delete</strong> <em>(const char * <var>url</var>, const char * <var>srk_password</var>)</em></dt>
<dd><p><var>url</var>: the URL describing the key
</p>
<p><var>srk_password</var>: a password for the SRK key
</p>
<p>This function will unregister the private key from the TPM
chip. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<hr>
<a name="Using-keys"></a>
<div class="header">
<p>
Next: <a href="#tpmtool-Invocation" accesskey="n" rel="next">tpmtool Invocation</a>, Previous: <a href="#Key-generation" accesskey="p" rel="prev">Key generation</a>, Up: <a href="#Trusted-Platform-Module" accesskey="u" rel="up">Trusted Platform Module</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Using-keys-1"></a>
<h4 class="subsection">5.4.3 Using keys</h4>

<a name="Importing-keys"></a>
<h4 class="subsubheading">Importing keys</h4>

<p>The TPM keys can be used directly by the abstract key types and do not require
any special structures. Moreover functions like <a href="#gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile2">gnutls_certificate_set_x509_key_file2</a>
can access TPM URLs.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fprivkey_005fimport_005ftpm_005fraw">gnutls_privkey_import_tpm_raw</a> (gnutls_privkey_t <var>pkey</var>, const gnutls_datum_t * <var>fdata</var>, gnutls_tpmkey_fmt_t <var>format</var>, const char * <var>srk_password</var>, const char * <var>key_password</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpubkey_005fimport_005ftpm_005fraw">gnutls_pubkey_import_tpm_raw</a> (gnutls_pubkey_t <var>pkey</var>, const gnutls_datum_t * <var>fdata</var>, gnutls_tpmkey_fmt_t <var>format</var>, const char * <var>srk_password</var>, unsigned int <var>flags</var>)</code></dt>
</dl>





<dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005ftpm_005furl"></a>Function: <em>int</em> <strong>gnutls_privkey_import_tpm_url</strong> <em>(gnutls_privkey_t <var>pkey</var>, const char * <var>url</var>, const char * <var>srk_password</var>, const char * <var>key_password</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>url</var>: The URL of the TPM key to be imported
</p>
<p><var>srk_password</var>: The password for the SRK key (optional)
</p>
<p><var>key_password</var>: A password for the key (optional)
</p>
<p><var>flags</var>: One of the GNUTLS_PRIVKEY_* flags
</p>
<p>This function will import the given private key to the abstract
<code>gnutls_privkey_t</code>  type.
</p>
<p>Note that unless <code>GNUTLS_PRIVKEY_DISABLE_CALLBACKS</code> 
is specified, if incorrect (or NULL) passwords are given
the PKCS11 callback functions will be used to obtain the
correct passwords. Otherwise if the SRK password is wrong
<code>GNUTLS_E_TPM_SRK_PASSWORD_ERROR</code>  is returned and if the key password
is wrong or not provided then <code>GNUTLS_E_TPM_KEY_PASSWORD_ERROR</code> 
is returned. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005ftpm_005furl"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_tpm_url</strong> <em>(gnutls_pubkey_t <var>pkey</var>, const char * <var>url</var>, const char * <var>srk_password</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The public key
</p>
<p><var>url</var>: The URL of the TPM key to be imported
</p>
<p><var>srk_password</var>: The password for the SRK key (optional)
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will import the given private key to the abstract
<code>gnutls_privkey_t</code>  type. 
</p>
<p>Note that unless <code>GNUTLS_PUBKEY_DISABLE_CALLBACKS</code> 
is specified, if incorrect (or NULL) passwords are given
the PKCS11 callback functions will be used to obtain the
correct passwords. Otherwise if the SRK password is wrong
<code>GNUTLS_E_TPM_SRK_PASSWORD_ERROR</code>  is returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="Listing-and-deleting-keys"></a>
<h4 class="subsubheading">Listing and deleting keys</h4>

<p>The registered keys (that are stored in the TPM) can be listed using one of
the following functions. Those keys are unfortunately only identified by
their UUID and have no label or other human friendly identifier.
Keys can be deleted from permament storage using <a href="#gnutls_005ftpm_005fprivkey_005fdelete">gnutls_tpm_privkey_delete</a>.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005ftpm_005fget_005fregistered">gnutls_tpm_get_registered</a> (gnutls_tpm_key_list_t * <var>list</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005ftpm_005fkey_005flist_005fdeinit">gnutls_tpm_key_list_deinit</a> (gnutls_tpm_key_list_t <var>list</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005ftpm_005fkey_005flist_005fget_005furl">gnutls_tpm_key_list_get_url</a> (gnutls_tpm_key_list_t <var>list</var>, unsigned int <var>idx</var>, char ** <var>url</var>, unsigned int <var>flags</var>)</code></dt>
</dl>





<dl>
<dt><a name="index-gnutls_005ftpm_005fprivkey_005fdelete-1"></a>Function: <em>int</em> <strong>gnutls_tpm_privkey_delete</strong> <em>(const char * <var>url</var>, const char * <var>srk_password</var>)</em></dt>
<dd><p><var>url</var>: the URL describing the key
</p>
<p><var>srk_password</var>: a password for the SRK key
</p>
<p>This function will unregister the private key from the TPM
chip. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>


<hr>
<a name="tpmtool-Invocation"></a>
<div class="header">
<p>
Previous: <a href="#Using-keys" accesskey="p" rel="prev">Using keys</a>, Up: <a href="#Trusted-Platform-Module" accesskey="u" rel="up">Trusted Platform Module</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Invoking-tpmtool"></a>
<h4 class="subsection">5.4.4 Invoking tpmtool</h4>
<a name="index-tpmtool"></a>


<p>Program that allows handling cryptographic data from the TPM chip.
</p>
<p>This section was generated by <strong>AutoGen</strong>,
using the <code>agtexi-cmd</code> template and the option descriptions for the <code>tpmtool</code> program.
This software is released under the GNU General Public License, version 3 or later.
</p>

<a name="tpmtool-usage"></a><a name="tpmtool-help_002fusage-_0028_002d_002dhelp_0029"></a>
<h4 class="subsection">5.4.5 tpmtool help/usage (<samp>--help</samp>)</h4>
<a name="index-tpmtool-help"></a>

<p>This is the automatically generated usage text for tpmtool.
</p>
<p>The text printed is the same whether selected with the <code>help</code> option
(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>).  <code>more-help</code> will print
the usage text by passing it through a pager program.
<code>more-help</code> is disabled on platforms without a working
<code>fork(2)</code> function.  The <code>PAGER</code> environment variable is
used to select the program, defaulting to <samp>more</samp>.  Both will exit
with a status code of 0.
</p>
<div class="example">
<pre class="example">tpmtool - GnuTLS TPM tool
Usage:  tpmtool [ -&lt;flag&gt; [&lt;val&gt;] | --&lt;name&gt;[{=| }&lt;val&gt;] ]...

   -d, --debug=num            Enable debugging
                                - it must be in the range:
                                  0 to 9999
       --infile=file          Input file
                                - file must pre-exist
       --outfile=str          Output file
       --generate-rsa         Generate an RSA private-public key pair
       --register             Any generated key will be registered in the TPM
                                - requires the option 'generate-rsa'
       --signing              Any generated key will be a signing key
                                - requires the option 'generate-rsa'
                                -- and prohibits the option 'legacy'
       --legacy               Any generated key will be a legacy key
                                - requires the option 'generate-rsa'
                                -- and prohibits the option 'signing'
       --user                 Any registered key will be a user key
                                - requires the option 'register'
                                -- and prohibits the option 'system'
       --system               Any registred key will be a system key
                                - requires the option 'register'
                                -- and prohibits the option 'user'
       --pubkey=str           Prints the public key of the provided key
       --list                 Lists all stored keys in the TPM
       --delete=str           Delete the key identified by the given URL (UUID).
       --test-sign=str        Tests the signature operation of the provided object
       --sec-param=str        Specify the security level [low, legacy, medium, high, ultra].
       --bits=num             Specify the number of bits for key generate
       --inder                Use the DER format for keys.
                                - disabled as '--no-inder'
       --outder               Use DER format for output keys
                                - disabled as '--no-outder'
   -v, --version[=arg]        output version information and exit
   -h, --help                 display extended usage information and exit
   -!, --more-help            extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.

Program that allows handling cryptographic data from the TPM chip.

</pre></div>

<a name="tpmtool-debug"></a><a name="debug-option-_0028_002dd_0029"></a>
<h4 class="subsection">5.4.6 debug option (-d)</h4>

<p>This is the &ldquo;enable debugging&rdquo; option.
This option takes a number argument.
Specifies the debug level.
<a name="tpmtool-generate_002drsa"></a></p><a name="generate_002drsa-option"></a>
<h4 class="subsection">5.4.7 generate-rsa option</h4>

<p>This is the &ldquo;generate an rsa private-public key pair&rdquo; option.
Generates an RSA private-public key pair in the TPM chip. 
The key may be stored in filesystem and protected by a PIN, or stored (registered)
in the TPM chip flash.
<a name="tpmtool-user"></a></p><a name="user-option"></a>
<h4 class="subsection">5.4.8 user option</h4>

<p>This is the &ldquo;any registered key will be a user key&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> must appear in combination with the following options:
register.
</li><li> must not appear in combination with any of the following options:
system.
</li></ul>

<p>The generated key will be stored in a user specific persistent storage.
<a name="tpmtool-system"></a></p><a name="system-option"></a>
<h4 class="subsection">5.4.9 system option</h4>

<p>This is the &ldquo;any registred key will be a system key&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> must appear in combination with the following options:
register.
</li><li> must not appear in combination with any of the following options:
user.
</li></ul>

<p>The generated key will be stored in system persistent storage.
<a name="tpmtool-test_002dsign"></a></p><a name="test_002dsign-option"></a>
<h4 class="subsection">5.4.10 test-sign option</h4>

<p>This is the &ldquo;tests the signature operation of the provided object&rdquo; option.
This option takes a string argument <samp>url</samp>.
It can be used to test the correct operation of the signature operation.
This operation will sign and verify the signed data.
<a name="tpmtool-sec_002dparam"></a></p><a name="sec_002dparam-option"></a>
<h4 class="subsection">5.4.11 sec-param option</h4>

<p>This is the &ldquo;specify the security level [low, legacy, medium, high, ultra].&rdquo; option.
This option takes a string argument <samp>Security parameter</samp>.
This is alternative to the bits option. Note however that the
values allowed by the TPM chip are quantized and given values may be rounded up.
<a name="tpmtool-inder"></a></p><a name="inder-option"></a>
<h4 class="subsection">5.4.12 inder option</h4>

<p>This is the &ldquo;use the der format for keys.&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-inder.
</li></ul>

<p>The input files will be assumed to be in the portable
DER format of TPM. The default format is a custom format used by various
TPM tools
<a name="tpmtool-outder"></a></p><a name="outder-option"></a>
<h4 class="subsection">5.4.13 outder option</h4>

<p>This is the &ldquo;use der format for output keys&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-outder.
</li></ul>

<p>The output will be in the TPM portable DER format.
<a name="tpmtool-exit-status"></a></p><a name="tpmtool-exit-status-1"></a>
<h4 class="subsection">5.4.14 tpmtool exit status</h4>

<p>One of the following exit values will be returned:
</p><dl compact="compact">
<dt>&lsquo;<samp>0 (EXIT_SUCCESS)</samp>&rsquo;</dt>
<dd><p>Successful program execution.
</p></dd>
<dt>&lsquo;<samp>1 (EXIT_FAILURE)</samp>&rsquo;</dt>
<dd><p>The operation failed or the command syntax was not valid.
</p></dd>
</dl>
<a name="tpmtool-See-Also"></a><a name="tpmtool-See-Also-1"></a>
<h4 class="subsection">5.4.15 tpmtool See Also</h4>
<p>p11tool (1), certtool (1)
<a name="tpmtool-Examples"></a></p><a name="tpmtool-Examples-1"></a>
<h4 class="subsection">5.4.16 tpmtool Examples</h4>
<p>To generate a key that is to be stored in filesystem use:
</p><div class="example">
<pre class="example">$ tpmtool --generate-rsa --bits 2048 --outfile tpmkey.pem
</pre></div>

<p>To generate a key that is to be stored in TPM&rsquo;s flash use:
</p><div class="example">
<pre class="example">$ tpmtool --generate-rsa --bits 2048 --register --user
</pre></div>

<p>To get the public key of a TPM key use:
</p><div class="example">
<pre class="example">$ tpmtool --pubkey tpmkey:uuid=58ad734b-bde6-45c7-89d8-756a55ad1891;storage=user \
          --outfile pubkey.pem
</pre></div>

<p>or if the key is stored in the filesystem:
</p><div class="example">
<pre class="example">$ tpmtool --pubkey tpmkey:file=tmpkey.pem --outfile pubkey.pem
</pre></div>

<p>To list all keys stored in TPM use:
</p><div class="example">
<pre class="example">$ tpmtool --list
</pre></div>


<hr>
<a name="How-to-use-GnuTLS-in-applications"></a>
<div class="header">
<p>
Next: <a href="#GnuTLS-application-examples" accesskey="n" rel="next">GnuTLS application examples</a>, Previous: <a href="#Hardware-security-modules-and-abstract-key-types" accesskey="p" rel="prev">Hardware security modules and abstract key types</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="How-to-use-GnuTLS-in-applications-1"></a>
<h2 class="chapter">6 How to use <acronym>GnuTLS</acronym> in applications</h2>

<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Introduction-to-the-library" accesskey="1">Introduction to the library</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Preparation" accesskey="2">Preparation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Session-initialization" accesskey="3">Session initialization</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Associating-the-credentials" accesskey="4">Associating the credentials</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Setting-up-the-transport-layer" accesskey="5">Setting up the transport layer</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#TLS-handshake" accesskey="6">TLS handshake</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Data-transfer-and-termination" accesskey="7">Data transfer and termination</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Buffered-data-transfer" accesskey="8">Buffered data transfer</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Handling-alerts" accesskey="9">Handling alerts</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Priority-Strings">Priority Strings</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Selecting-cryptographic-key-sizes">Selecting cryptographic key sizes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Advanced-topics">Advanced topics</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Introduction-to-the-library"></a>
<div class="header">
<p>
Next: <a href="#Preparation" accesskey="n" rel="next">Preparation</a>, Up: <a href="#How-to-use-GnuTLS-in-applications" accesskey="u" rel="up">How to use GnuTLS in applications</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Introduction"></a>
<h3 class="section">6.1 Introduction</h3>

<p>This chapter tries to explain the basic functionality of the current GnuTLS
library. Note that there may be additional functionality not discussed here
but included in the library. Checking the header files in <samp>/usr/include/gnutls/</samp>
and the manpages is recommended.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#General-idea" accesskey="1">General idea</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Error-handling" accesskey="2">Error handling</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Common-types" accesskey="3">Common types</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Debugging-and-auditing" accesskey="4">Debugging and auditing</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Thread-safety" accesskey="5">Thread safety</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Running-in-a-sandbox" accesskey="6">Running in a sandbox</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Sessions-and-fork" accesskey="7">Sessions and fork</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Callback-functions" accesskey="8">Callback functions</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="General-idea"></a>
<div class="header">
<p>
Next: <a href="#Error-handling" accesskey="n" rel="next">Error handling</a>, Up: <a href="#Introduction-to-the-library" accesskey="u" rel="up">Introduction to the library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="General-idea-1"></a>
<h4 class="subsection">6.1.1 General idea</h4>

<p>A brief description of how <acronym>GnuTLS</acronym> sessions operate is shown
at <a href="#fig_002dgnutls_002ddesign">Figure 6.1</a>. This section will become more clear when it
is completely read.
As shown in the figure, there is a read-only global state that is
initialized once by the global initialization function.  This global
structure, among others, contains the memory allocation functions
used, structures needed for the <acronym>ASN.1</acronym> parser and depending
on the system&rsquo;s CPU, pointers to hardware accelerated encryption functions.  This
structure is never modified by any <acronym>GnuTLS</acronym> function, except
for the deinitialization function which frees all allocated memory
and must be called after the program has permanently
finished using <acronym>GnuTLS</acronym>.
</p>
<div class="float"><a name="fig_002dgnutls_002ddesign"></a>
<img src="gnutls-internals.png" alt="gnutls-internals">

<div class="float-caption"><p><strong>Figure 6.1: </strong>High level design of GnuTLS.</p></div></div>
<p>The credentials structures are used by the authentication methods, such
as certificate authentication. They store certificates, privates keys,
and other information that is needed to prove the identity to the peer,
and/or verify the indentity of the peer. The information stored in
the credentials structures is initialized once and then can be 
shared by many <acronym>TLS</acronym> sessions.
</p>
<p>A <acronym>GnuTLS</acronym> session contains all the required state and 
information to handle one secure connection. The session communicates with the
peers using the provided functions of the transport layer.
Every session has a unique session ID shared with the peer.
</p>
<p>Since TLS sessions can be resumed, servers need a
database back-end to hold the session&rsquo;s parameters.  Every
<acronym>GnuTLS</acronym> session after a successful handshake calls the
appropriate back-end function (see <a href="#resume">resume</a>)
to store the newly negotiated session. The session
database is examined by the server just after having received the
client hello<a name="DOCF14" href="#FOOT14"><sup>14</sup></a>,
and if the session ID sent by the client, matches a stored session,
the stored session will be retrieved, and the new session will be a
resumed one, and will share the same session ID with the previous one.
</p>
<hr>
<a name="Error-handling"></a>
<div class="header">
<p>
Next: <a href="#Common-types" accesskey="n" rel="next">Common types</a>, Previous: <a href="#General-idea" accesskey="p" rel="prev">General idea</a>, Up: <a href="#Introduction-to-the-library" accesskey="u" rel="up">Introduction to the library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Error-handling-1"></a>
<h4 class="subsection">6.1.2 Error handling</h4>

<p>In <acronym>GnuTLS</acronym> most functions return an integer type as a result.
In almost all cases a zero or a positive number means success, and a
negative number indicates failure, or a situation that some action has
to be taken. Thus negative error codes may be fatal or not.
</p>
<p>Fatal errors terminate the connection immediately and further sends
and receives will be disallowed.  Such an example is
<code>GNUTLS_E_DECRYPTION_FAILED</code>. Non-fatal errors may warn about
something, i.e., a warning alert was received, or indicate the some
action has to be taken. This is the case with the error code
<code>GNUTLS_E_REHANDSHAKE</code> returned by <a href="#gnutls_005frecord_005frecv">gnutls_record_recv</a>.
This error code indicates that the server requests a re-handshake. The
client may ignore this request, or may reply with an alert.  You can
test if an error code is a fatal one by using the
<a href="#gnutls_005ferror_005fis_005ffatal">gnutls_error_is_fatal</a>.
All errors can be converted to a descriptive string using <a href="#gnutls_005fstrerror">gnutls_strerror</a>.
</p>
<p>If any non fatal errors, that require an action, are to be returned by
a function, these error codes will be documented in the function&rsquo;s
reference. For example the error codes <code>GNUTLS_E_WARNING_ALERT_RECEIVED</code> and <code>GNUTLS_E_FATAL_ALERT_RECEIVED</code>
that may returned when receiving data, should be handled by notifying the
user of the alert (as explained in <a href="#Handling-alerts">Handling alerts</a>).
See <a href="#Error-codes">Error codes</a>, for a description of the available error codes.
</p>
<hr>
<a name="Common-types"></a>
<div class="header">
<p>
Next: <a href="#Debugging-and-auditing" accesskey="n" rel="next">Debugging and auditing</a>, Previous: <a href="#Error-handling" accesskey="p" rel="prev">Error handling</a>, Up: <a href="#Introduction-to-the-library" accesskey="u" rel="up">Introduction to the library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Common-types-1"></a>
<h4 class="subsection">6.1.3 Common types</h4>

<p>All strings that are to provided as input to <acronym>GnuTLS</acronym> functions
should be in UTF-8 unless otherwise specified. Output strings are also
in UTF-8 format unless otherwise specified.
</p>
<p>When data of a fixed size are provided to <acronym>GnuTLS</acronym> functions then
the helper structure <code>gnutls_datum_t</code> is often used. Its definition is
shown below.
</p><pre class="verbatim">  typedef struct
  {
    unsigned char *data;
    unsigned int size;
  } gnutls_datum_t;
</pre>
<p>Other functions that require data for scattered read use a structure similar
to <code>struct iovec</code> typically used by <code>readv</code>. It is shown
below.
</p><pre class="verbatim">  typedef struct
  {
    void *iov_base;             /* Starting address */
    size_t iov_len;             /* Number of bytes to transfer */
  } giovec_t;
</pre>

<hr>
<a name="Debugging-and-auditing"></a>
<div class="header">
<p>
Next: <a href="#Thread-safety" accesskey="n" rel="next">Thread safety</a>, Previous: <a href="#Common-types" accesskey="p" rel="prev">Common types</a>, Up: <a href="#Introduction-to-the-library" accesskey="u" rel="up">Introduction to the library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Debugging-and-auditing-1"></a>
<h4 class="subsection">6.1.4 Debugging and auditing</h4>

<p>In many cases things may not go as expected and further information,
to assist debugging, from <acronym>GnuTLS</acronym> is desired. 
Those are the cases where the <a href="#gnutls_005fglobal_005fset_005flog_005flevel">gnutls_global_set_log_level</a> and
<a href="#gnutls_005fglobal_005fset_005flog_005ffunction">gnutls_global_set_log_function</a> are to be used. Those will print
verbose information on the <acronym>GnuTLS</acronym> functions internal flow.
</p>
<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005fglobal_005fset_005flog_005flevel">gnutls_global_set_log_level</a> (int <var>level</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fglobal_005fset_005flog_005ffunction">gnutls_global_set_log_function</a> (gnutls_log_func <var>log_func</var>)</code></dt>
</dl>

<p>Alternatively the environment variable <code>GNUTLS_DEBUG_LEVEL</code> can be
set to a logging level and GnuTLS will output debugging output to standard
error. Other available environment variables are shown in <a href="#tab_003aenvironment">Table 6.1</a>.
</p>
<div class="float"><a name="tab_003aenvironment"></a>
<table>
<thead><tr><th width="30%">Variable</th><th width="70%">Purpose</th></tr></thead>
<tr><td width="30%"><code>GNUTLS_DEBUG_LEVEL</code></td><td width="70%">When set to a numeric value, it sets the default debugging level for GnuTLS applications.</td></tr>
<tr><td width="30%"><code>GNUTLS_CPUID_OVERRIDE</code></td><td width="70%">That environment variable can be used to
explicitly enable/disable the use of certain CPU capabilities. Note that CPU
detection cannot be overriden, i.e., VIA options cannot be enabled on an Intel
CPU. The currently available options are:
<ul>
<li> 0x1: Disable all run-time detected optimizations
</li><li> 0x2: Enable AES-NI
</li><li> 0x4: Enable SSSE3
</li><li> 0x8: Enable PCLMUL
</li><li> 0x100000: Enable VIA padlock
</li><li> 0x200000: Enable VIA PHE
</li><li> 0x400000: Enable VIA PHE SHA512
</li></ul></td></tr>
<tr><td width="30%"><code>GNUTLS_FORCE_FIPS_MODE</code></td><td width="70%">In setups where GnuTLS is compiled with support for FIPS140-2 (see &ndash;enable-fips140-mode in configure), that option if set to one enforces the FIPS140 mode.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 6.1: </strong>Environment variables used by the library.</p></div></div>

<p>When debugging is not required, important issues, such as detected
attacks on the protocol still need to be logged. This is provided
by the logging function set by
<a href="#gnutls_005fglobal_005fset_005faudit_005flog_005ffunction">gnutls_global_set_audit_log_function</a>. The provided function
will receive an message and the corresponding
TLS session. The session information might be used to derive IP addresses
or other information about the peer involved.
</p>




<dl>
<dt><a name="index-gnutls_005fglobal_005fset_005faudit_005flog_005ffunction"></a>Function: <em>void</em> <strong>gnutls_global_set_audit_log_function</strong> <em>(gnutls_audit_log_func <var>log_func</var>)</em></dt>
<dd><p><var>log_func</var>: it is the audit log function
</p>
<p>This is the function to set the audit logging function. This
is a function to report important issues, such as possible
attacks in the protocol. This is different from <code>gnutls_global_set_log_function()</code> 
because it will report also session-specific events. The session
parameter will be null if there is no corresponding TLS session.
</p>
<p><code>gnutls_audit_log_func</code> is of the form,
void (*gnutls_audit_log_func)( gnutls_session_t, const char*);
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<hr>
<a name="Thread-safety"></a>
<div class="header">
<p>
Next: <a href="#Running-in-a-sandbox" accesskey="n" rel="next">Running in a sandbox</a>, Previous: <a href="#Debugging-and-auditing" accesskey="p" rel="prev">Debugging and auditing</a>, Up: <a href="#Introduction-to-the-library" accesskey="u" rel="up">Introduction to the library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Thread-safety-1"></a>
<h4 class="subsection">6.1.5 Thread safety</h4>
<a name="index-thread-safety"></a>

<p>The <acronym>GnuTLS</acronym> library is thread safe by design, meaning that
objects of the library such as TLS sessions, can be safely divided across
threads as long as a single thread accesses a single object. This is
sufficient to support a server which handles several sessions per thread.
If, however, an object needs to be shared across threads then access must be 
protected with a mutex. Read-only access to objects, for example the
credentials holding structures, is also thread-safe. 
</p>
<p>A <code>gnutls_session_t</code> object can be shared by two threads, one sending,
the other receiving. In that case rehandshakes, if required,
must only be handled by a single thread being active. The termination of a session 
should be handled, either by a single thread being active, or by the sender thread 
using <a href="#gnutls_005fbye">gnutls_bye</a> with <code>GNUTLS_SHUT_WR</code> and the receiving thread 
waiting for a return value of zero.
</p>
<p>The random generator of the cryptographic back-end, utilizes mutex locks (e.g., pthreads on GNU/Linux and CriticalSection on Windows)
which are setup by <acronym>GnuTLS</acronym> on library initialization. Prior to version 3.3.0
they were setup by calling <a href="#gnutls_005fglobal_005finit">gnutls_global_init</a>. On special systems
you could manually specify the locking system using
the function <a href="#gnutls_005fglobal_005fset_005fmutex">gnutls_global_set_mutex</a> before calling any other
GnuTLS function. Setting mutexes manually is not recommended.
An example of non-native thread usage is shown below.
</p>
<div class="example">
<pre class="example">#include &lt;gnutls/gnutls.h&gt;

int main()
{
   /* When the system mutexes are not to be used 
    * gnutls_global_set_mutex() must be called explicitly
    */
   gnutls_global_set_mutex (mutex_init, mutex_deinit, 
                            mutex_lock, mutex_unlock);
}
</pre></div>





<dl>
<dt><a name="index-gnutls_005fglobal_005fset_005fmutex"></a>Function: <em>void</em> <strong>gnutls_global_set_mutex</strong> <em>(mutex_init_func <var>init</var>, mutex_deinit_func <var>deinit</var>, mutex_lock_func <var>lock</var>, mutex_unlock_func <var>unlock</var>)</em></dt>
<dd><p><var>init</var>: mutex initialization function
</p>
<p><var>deinit</var>: mutex deinitialization function
</p>
<p><var>lock</var>: mutex locking function
</p>
<p><var>unlock</var>: mutex unlocking function
</p>
<p>With this function you are allowed to override the default mutex
locks used in some parts of gnutls and dependent libraries. This function
should be used if you have complete control of your program and libraries.
Do not call this function from a library, or preferably from any application
unless really needed to. GnuTLS will use the appropriate locks for the running
system.
</p>
<p>This function must be called prior to any other gnutls function.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<hr>
<a name="Running-in-a-sandbox"></a>
<div class="header">
<p>
Next: <a href="#Sessions-and-fork" accesskey="n" rel="next">Sessions and fork</a>, Previous: <a href="#Thread-safety" accesskey="p" rel="prev">Thread safety</a>, Up: <a href="#Introduction-to-the-library" accesskey="u" rel="up">Introduction to the library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Running-in-a-sandbox-1"></a>
<h4 class="subsection">6.1.6 Running in a sandbox</h4>
<a name="index-seccomp"></a>
<a name="index-isolated-mode"></a>

<p>Given that TLS protocol handling as well as X.509 certificate
parsing are complicated processes involving several thousands lines of code,
it is often desirable (and recommended) to run the TLS session handling in
a sandbox like seccomp. That has to be allowed by the overall software design,
but if available, it adds an additional layer of protection by
preventing parsing errors from becoming vessels for further security issues such
as code execution.
</p>
<p>GnuTLS requires the following system calls to be available for its proper
operation.
</p>
<ul>
<li> nanosleep
</li><li> time
</li><li> gettimeofday
</li><li> clock_gettime
</li><li> getrusage
</li><li> send
</li><li> recv
</li><li> writev
</li><li> read (to read from /dev/urandom)
</li><li> getrandom (this is Linux-kernel specific)
</li><li> select
</li></ul>

<p>As well as an calls needed for memory allocation to work. Note however, that GnuTLS
depends on libc for the system calls, and there is no guarrantee that libc will
call the expected system call. For that it is recommended to test your
program in all the targetted platforms when filters like seccomp are in place.
</p>
<p>An example with a seccomp filter from GnuTLS&rsquo; test suite is at:
<a href="http://gitlab.com/gnutls/gnutls/blob/master/tests/seccomp.c">http://gitlab.com/gnutls/gnutls/blob/master/tests/seccomp.c</a>.
</p>
<hr>
<a name="Sessions-and-fork"></a>
<div class="header">
<p>
Next: <a href="#Callback-functions" accesskey="n" rel="next">Callback functions</a>, Previous: <a href="#Running-in-a-sandbox" accesskey="p" rel="prev">Running in a sandbox</a>, Up: <a href="#Introduction-to-the-library" accesskey="u" rel="up">Introduction to the library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Sessions-and-fork-1"></a>
<h4 class="subsection">6.1.7 Sessions and fork</h4>
<a name="index-fork"></a>

<p>A <code>gnutls_session_t</code> object can be shared by two processes after a fork,
one sending, the other receiving. In that case rehandshakes, 
cannot and must not be performed. As with threads, the termination of a session should be
handled by the sender process using <a href="#gnutls_005fbye">gnutls_bye</a> with <code>GNUTLS_SHUT_WR</code>
and the receiving process waiting for a return value of zero.
</p>

<hr>
<a name="Callback-functions"></a>
<div class="header">
<p>
Previous: <a href="#Sessions-and-fork" accesskey="p" rel="prev">Sessions and fork</a>, Up: <a href="#Introduction-to-the-library" accesskey="u" rel="up">Introduction to the library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Callback-functions-1"></a>
<h4 class="subsection">6.1.8 Callback functions</h4>
<a name="index-callback-functions"></a>

<p>There are several cases where <acronym>GnuTLS</acronym> may need out of
band input from your program. This is now implemented using some
callback functions, which your program is expected to register.
</p>
<p>An example of this type of functions are the push and pull callbacks
which are used to specify the functions that will retrieve and send
data to the transport layer.
</p>
<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005ftransport_005fset_005fpush_005ffunction">gnutls_transport_set_push_function</a> (gnutls_session_t <var>session</var>, gnutls_push_func <var>push_func</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005ftransport_005fset_005fpull_005ffunction">gnutls_transport_set_pull_function</a> (gnutls_session_t <var>session</var>, gnutls_pull_func <var>pull_func</var>)</code></dt>
</dl>

<p>Other callback functions may require more complicated input and data
to be allocated. Such an example is 
<a href="#gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffunction">gnutls_srp_set_server_credentials_function</a>.
All callbacks should allocate and free memory using 
<code>gnutls_malloc</code> and <code>gnutls_free</code>.
</p>

<hr>
<a name="Preparation"></a>
<div class="header">
<p>
Next: <a href="#Session-initialization" accesskey="n" rel="next">Session initialization</a>, Previous: <a href="#Introduction-to-the-library" accesskey="p" rel="prev">Introduction to the library</a>, Up: <a href="#How-to-use-GnuTLS-in-applications" accesskey="u" rel="up">How to use GnuTLS in applications</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Preparation-1"></a>
<h3 class="section">6.2 Preparation</h3>

<p>To use <acronym>GnuTLS</acronym>, you have to perform some changes to your
sources and your build system. The necessary changes are explained in
the following subsections.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Headers" accesskey="1">Headers</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Initialization" accesskey="2">Initialization</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Version-check" accesskey="3">Version check</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Building-the-source" accesskey="4">Building the source</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Headers"></a>
<div class="header">
<p>
Next: <a href="#Initialization" accesskey="n" rel="next">Initialization</a>, Up: <a href="#Preparation" accesskey="u" rel="up">Preparation</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Headers-1"></a>
<h4 class="subsection">6.2.1 Headers</h4>

<p>All the data types and functions of the <acronym>GnuTLS</acronym> library are
defined in the header file <samp>gnutls/gnutls.h</samp>.  This must be
included in all programs that make use of the <acronym>GnuTLS</acronym>
library.
</p>
<hr>
<a name="Initialization"></a>
<div class="header">
<p>
Next: <a href="#Version-check" accesskey="n" rel="next">Version check</a>, Previous: <a href="#Headers" accesskey="p" rel="prev">Headers</a>, Up: <a href="#Preparation" accesskey="u" rel="up">Preparation</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Initialization-2"></a>
<h4 class="subsection">6.2.2 Initialization</h4>

<p>The GnuTLS library is initialized on load; prior to 3.3.0 was initialized by calling <a href="#gnutls_005fglobal_005finit">gnutls_global_init</a><a name="DOCF15" href="#FOOT15"><sup>15</sup></a>. 
The initialization typically enables CPU-specific acceleration, performs any required
precalculations needed, opens any required system devices (e.g., /dev/urandom on Linux)
and initializes subsystems that could be used later.
</p>
<p>The resources allocated by the initialization process will be released 
on library deinitialization, or explictly by calling <a href="#gnutls_005fglobal_005fdeinit">gnutls_global_deinit</a>.
</p>
<p>Note that during initialization file descriptors may be kept open by
GnuTLS (e.g. /dev/urandom) on library load. Applications closing all unknown file
descriptors must immediately call <a href="#gnutls_005fglobal_005finit">gnutls_global_init</a>, after that, to
ensure they don&rsquo;t disrupt GnuTLS&rsquo; operation.
</p>

<hr>
<a name="Version-check"></a>
<div class="header">
<p>
Next: <a href="#Building-the-source" accesskey="n" rel="next">Building the source</a>, Previous: <a href="#Initialization" accesskey="p" rel="prev">Initialization</a>, Up: <a href="#Preparation" accesskey="u" rel="up">Preparation</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Version-check-1"></a>
<h4 class="subsection">6.2.3 Version check</h4>

<p>It is often desirable to check that the version of &lsquo;gnutls&rsquo; used is
indeed one which fits all requirements.  Even with binary
compatibility new features may have been introduced but due to problem
with the dynamic linker an old version is actually used.  So you may
want to check that the version is okay right after program start-up.
See the function <a href="#gnutls_005fcheck_005fversion">gnutls_check_version</a>.
</p>
<p>On the other hand, it is often desirable to support more than one
versions of the library. In that case you could utilize compile-time 
feature checks using the the <code>GNUTLS_VERSION_NUMBER</code> macro. 
For example, to conditionally add code for GnuTLS 3.2.1 or later, you may use:
</p><div class="example">
<pre class="example">#if GNUTLS_VERSION_NUMBER &gt;= 0x030201
 ...
#endif
</pre></div>

<hr>
<a name="Building-the-source"></a>
<div class="header">
<p>
Previous: <a href="#Version-check" accesskey="p" rel="prev">Version check</a>, Up: <a href="#Preparation" accesskey="u" rel="up">Preparation</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Building-the-source-1"></a>
<h4 class="subsection">6.2.4 Building the source</h4>

<p>If you want to compile a source file including the
<samp>gnutls/gnutls.h</samp> header file, you must make sure that the
compiler can find it in the directory hierarchy.  This is accomplished
by adding the path to the directory in which the header file is
located to the compilers include file search path (via the <samp>-I</samp>
option).
</p>
<p>However, the path to the include file is determined at the time the
source is configured.  To solve this problem, the library uses the
external package <code>pkg-config</code> that knows the path to the
include file and other configuration options.  The options that need
to be added to the compiler invocation at compile time are output by
the <samp>--cflags</samp> option to <code>pkg-config gnutls</code>.  The
following example shows how it can be used at the command line:
</p>
<div class="example">
<pre class="example">gcc -c foo.c `pkg-config gnutls --cflags`
</pre></div>

<p>Adding the output of &lsquo;<samp>pkg-config gnutls --cflags</samp>&rsquo; to the
compilers command line will ensure that the compiler can find the
<samp>gnutls/gnutls.h</samp> header file.
</p>
<p>A similar problem occurs when linking the program with the library.
Again, the compiler has to find the library files.  For this to work,
the path to the library files has to be added to the library search
path (via the <samp>-L</samp> option).  For this, the option
<samp>--libs</samp> to <code>pkg-config gnutls</code> can be used.  For
convenience, this option also outputs all other options that are
required to link the program with the library (for instance, the
&lsquo;<samp>-ltasn1</samp>&rsquo; option).  The example shows how to link <samp>foo.o</samp>
with the library to a program <code>foo</code>.
</p>
<div class="example">
<pre class="example">gcc -o foo foo.o `pkg-config gnutls --libs`
</pre></div>

<p>Of course you can also combine both examples to a single command by
specifying both options to <code>pkg-config</code>:
</p>
<div class="example">
<pre class="example">gcc -o foo foo.c `pkg-config gnutls --cflags --libs`
</pre></div>

<p>When a program uses the GNU autoconf system, then the following
line or similar can be used to detect the presence of GnuTLS.
</p>
<div class="example">
<pre class="example">PKG_CHECK_MODULES([LIBGNUTLS], [gnutls &gt;= 3.3.0])

AC_SUBST([LIBGNUTLS_CFLAGS])
AC_SUBST([LIBGNUTLS_LIBS])
</pre></div>

<hr>
<a name="Session-initialization"></a>
<div class="header">
<p>
Next: <a href="#Associating-the-credentials" accesskey="n" rel="next">Associating the credentials</a>, Previous: <a href="#Preparation" accesskey="p" rel="prev">Preparation</a>, Up: <a href="#How-to-use-GnuTLS-in-applications" accesskey="u" rel="up">How to use GnuTLS in applications</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Session-initialization-1"></a>
<h3 class="section">6.3 Session initialization</h3>

<p>In the previous sections we have discussed the global initialization
required for GnuTLS as well as the initialization required for each
authentication method&rsquo;s credentials (see <a href="#Authentication">Authentication</a>).
In this section we elaborate on the TLS or DTLS session initiation.
Each session is initialized using <a href="#gnutls_005finit">gnutls_init</a> which among
others is used to specify the type of the connection (server or client), 
and the underlying protocol type, i.e., datagram (UDP) or reliable (TCP).
</p>




<dl>
<dt><a name="index-gnutls_005finit"></a>Function: <em>int</em> <strong>gnutls_init</strong> <em>(gnutls_session_t * <var>session</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>session</var>: is a pointer to a <code>gnutls_session_t</code>  type.
</p>
<p><var>flags</var>: indicate if this session is to be used for server or client.
</p>
<p>This function initializes the current session to null. Every
session must be initialized before use, so internal structures can
be allocated.  This function allocates structures which can only
be free&rsquo;d by calling <code>gnutls_deinit()</code> .  Returns <code>GNUTLS_E_SUCCESS</code>  (0) on success.
</p>
<p><code>flags</code> can be one of <code>GNUTLS_CLIENT</code> , <code>GNUTLS_SERVER</code> , <code>GNUTLS_DATAGRAM</code> ,
<code>GNUTLS_NONBLOCK</code>  or <code>GNUTLS_NOSIGNAL</code>  (since 3.4.2).
</p>
<p>The flag <code>GNUTLS_NO_REPLAY_PROTECTION</code>  will disable any 
replay protection in DTLS mode. That must only used when 
replay protection is achieved using other means.
</p>
<p>Note that since version 3.1.2 this function enables some common
TLS extensions such as session tickets and OCSP certificate status
request in client side by default. To prevent that use the <code>GNUTLS_NO_EXTENSIONS</code> 
flag.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<p>After the session initialization details on the allowed ciphersuites
and protocol versions should be set using the priority functions
such as <a href="#gnutls_005fpriority_005fset_005fdirect">gnutls_priority_set_direct</a>. We elaborate on them
in <a href="#Priority-Strings">Priority Strings</a>.
The credentials used for the key exchange method, such as certificates 
or usernames and passwords should also be associated with the session
current session using <a href="#gnutls_005fcredentials_005fset">gnutls_credentials_set</a>. 
</p>




<dl>
<dt><a name="index-gnutls_005fcredentials_005fset"></a>Function: <em>int</em> <strong>gnutls_credentials_set</strong> <em>(gnutls_session_t <var>session</var>, gnutls_credentials_type_t <var>type</var>, void * <var>cred</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>type</var>: is the type of the credentials
</p>
<p><var>cred</var>: the credentials to set
</p>
<p>Sets the needed credentials for the specified type.  Eg username,
password - or public and private keys etc.  The  <code>cred</code> parameter is
a structure that depends on the specified type and on the current
session (client or server).
</p>
<p>In order to minimize memory usage, and share credentials between
several threads gnutls keeps a pointer to cred, and not the whole
cred structure.  Thus you will have to keep the structure allocated
until you call <code>gnutls_deinit()</code> .
</p>
<p>For <code>GNUTLS_CRD_ANON</code> ,  <code>cred</code> should be
<code>gnutls_anon_client_credentials_t</code>  in case of a client.  In case of
a server it should be <code>gnutls_anon_server_credentials_t</code> .
</p>
<p>For <code>GNUTLS_CRD_SRP</code> ,  <code>cred</code> should be <code>gnutls_srp_client_credentials_t</code> 
in case of a client, and <code>gnutls_srp_server_credentials_t</code> , in case
of a server.
</p>
<p>For <code>GNUTLS_CRD_CERTIFICATE</code> ,  <code>cred</code> should be
<code>gnutls_certificate_credentials_t</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<hr>
<a name="Associating-the-credentials"></a>
<div class="header">
<p>
Next: <a href="#Setting-up-the-transport-layer" accesskey="n" rel="next">Setting up the transport layer</a>, Previous: <a href="#Session-initialization" accesskey="p" rel="prev">Session initialization</a>, Up: <a href="#How-to-use-GnuTLS-in-applications" accesskey="u" rel="up">How to use GnuTLS in applications</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Associating-the-credentials-1"></a>
<h3 class="section">6.4 Associating the credentials</h3>

<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Certificate-credentials" accesskey="1">Certificate credentials</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#SRP-credentials" accesskey="2">SRP credentials</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#PSK-credentials" accesskey="3">PSK credentials</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Anonymous-credentials" accesskey="4">Anonymous credentials</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<p>Each authentication method is associated with a key exchange method, and a credentials type. 
The contents of the credentials is method-dependent, e.g. certificates
for certificate authentication and should be initialized and associated
with a session (see <a href="#gnutls_005fcredentials_005fset">gnutls_credentials_set</a>).  A mapping of the key exchange methods
with the credential types is shown in <a href="#tab_003akey_002dexchange_002dcred">Table 6.2</a>.
</p>
<div class="float"><a name="tab_003akey_002dexchange_002dcred"></a>
<table>
<thead><tr><th width="25%">Authentication method</th><th width="25%">Key exchange</th><th width="20%">Client credentials</th><th width="20%">Server credentials</th></tr></thead>
<tr><td width="25%">Certificate</td><td width="25%"><code>KX_RSA</code>,
<code>KX_DHE_RSA</code>,
<code>KX_DHE_DSS</code>,
<code>KX_ECDHE_RSA</code>,
<code>KX_ECDHE_ECDSA</code>,
<code>KX_RSA_EXPORT</code></td><td width="20%"><code>CRD_CERTIFICATE</code></td><td width="20%"><code>CRD_CERTIFICATE</code></td></tr>
<tr><td width="25%">Password and certificate</td><td width="25%"><code>KX_SRP_RSA</code>, <code>KX_SRP_DSS</code></td><td width="20%"><code>CRD_SRP</code></td><td width="20%"><code>CRD_CERTIFICATE</code>, <code>CRD_SRP</code></td></tr>
<tr><td width="25%">Password</td><td width="25%"><code>KX_SRP</code></td><td width="20%"><code>CRD_SRP</code></td><td width="20%"><code>CRD_SRP</code></td></tr>
<tr><td width="25%">Anonymous</td><td width="25%"><code>KX_ANON_DH</code>,
<code>KX_ANON_ECDH</code></td><td width="20%"><code>CRD_ANON</code></td><td width="20%"><code>CRD_ANON</code></td></tr>
<tr><td width="25%">Pre-shared key</td><td width="25%"><code>KX_PSK</code>,
<code>KX_DHE_PSK</code>, <code>KX_ECDHE_PSK</code></td><td width="20%"><code>CRD_PSK</code></td><td width="20%"><code>CRD_PSK</code></td></tr>
</table>

<div class="float-caption"><p><strong>Table 6.2: </strong>Key exchange algorithms and the corresponding credential types.</p></div></div>
<hr>
<a name="Certificate-credentials"></a>
<div class="header">
<p>
Next: <a href="#SRP-credentials" accesskey="n" rel="next">SRP credentials</a>, Up: <a href="#Associating-the-credentials" accesskey="u" rel="up">Associating the credentials</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Certificates"></a>
<h4 class="subsection">6.4.1 Certificates</h4>
<a name="Server-certificate-authentication"></a>
<h4 class="subsubheading">Server certificate authentication</h4>

<p>When using certificates the server is required to have at least one
certificate and private key pair. Clients may not hold such
a pair, but a server could require it. In this section we discuss
general issues applying to both client and server certificates. The next
section will elaborate on issues arising from client authentication only.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fallocate_005fcredentials">gnutls_certificate_allocate_credentials</a> (gnutls_certificate_credentials_t *      <var>res</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fcertificate_005ffree_005fcredentials">gnutls_certificate_free_credentials</a> (gnutls_certificate_credentials_t <var>sc</var>)</code></dt>
</dl>

<p>After the credentials structures are initialized, the certificate 
and key pair must be loaded. This occurs before any <acronym>TLS</acronym> 
session is initialized, and the same structures are reused for multiple sessions.
Depending on the certificate type different loading functions
are available, as shown below.
For <acronym>X.509</acronym> certificates, the functions will
accept and use a certificate chain that leads to a trusted
authority. The certificate chain must be ordered in such way that every
certificate certifies the one before it. The trusted authority&rsquo;s
certificate need not to be included since the peer should possess it
already.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile2">gnutls_certificate_set_x509_key_file2</a> (gnutls_certificate_credentials_t <var>res</var>, const char * <var>certfile</var>, const char * <var>keyfile</var>, gnutls_x509_crt_fmt_t <var>type</var>, const char * <var>pass</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fx509_005fkey_005fmem2">gnutls_certificate_set_x509_key_mem2</a> (gnutls_certificate_credentials_t <var>res</var>, const gnutls_datum_t * <var>cert</var>, const gnutls_datum_t * <var>key</var>, gnutls_x509_crt_fmt_t <var>type</var>, const char * <var>pass</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fx509_005fkey">gnutls_certificate_set_x509_key</a> (gnutls_certificate_credentials_t <var>res</var>, gnutls_x509_crt_t * <var>cert_list</var>, int <var>cert_list_size</var>, gnutls_x509_privkey_t <var>key</var>)</code></dt>
</dl>

<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005ffile">gnutls_certificate_set_openpgp_key_file</a> (gnutls_certificate_credentials_t      <var>res</var>, const char * <var>certfile</var>, const char * <var>keyfile</var>, gnutls_openpgp_crt_fmt_t <var>format</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005fmem">gnutls_certificate_set_openpgp_key_mem</a> (gnutls_certificate_credentials_t            <var>res</var>, const gnutls_datum_t * <var>cert</var>, const gnutls_datum_t * <var>key</var>, gnutls_openpgp_crt_fmt_t <var>format</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fopenpgp_005fkey">gnutls_certificate_set_openpgp_key</a> (gnutls_certificate_credentials_t <var>res</var>, gnutls_openpgp_crt_t <var>crt</var>, gnutls_openpgp_privkey_t <var>pkey</var>)</code></dt>
</dl>

<p>It is recommended to use the higher level functions such as <a href="#gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile2">gnutls_certificate_set_x509_key_file2</a>
which accept not only file names but URLs that specify objects stored in token,
or system certificates and keys (see <a href="#Application_002dspecific-keys">Application-specific keys</a>). For these cases, another important 
function is <a href="#gnutls_005fcertificate_005fset_005fpin_005ffunction">gnutls_certificate_set_pin_function</a>, that
allows setting a callback function to retrieve a PIN if the input keys are
protected by PIN.
</p>




<dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fpin_005ffunction"></a>Function: <em>void</em> <strong>gnutls_certificate_set_pin_function</strong> <em>(gnutls_certificate_credentials_t       <var>cred</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>fn</var>: A PIN callback
</p>
<p><var>userdata</var>: Data to be passed in the callback
</p>
<p>This function will set a callback function to be used when
required to access a protected object. This function overrides any other
global PIN functions.
</p>
<p>Note that this function must be called right after initialization
to have effect.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<p>If the imported keys and certificates need to be accessed before any TLS session
is established, it is convenient to use <a href="#gnutls_005fcertificate_005fset_005fkey">gnutls_certificate_set_key</a>
in combination with <a href="#gnutls_005fpcert_005fimport_005fx509_005fraw">gnutls_pcert_import_x509_raw</a> and <a href="#gnutls_005fprivkey_005fimport_005fx509_005fraw">gnutls_privkey_import_x509_raw</a>.
</p>



<dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fkey"></a>Function: <em>int</em> <strong>gnutls_certificate_set_key</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, const char ** <var>names</var>, int <var>names_size</var>, gnutls_pcert_st * <var>pcert_list</var>, int <var>pcert_list_size</var>, gnutls_privkey_t <var>key</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>names</var>: is an array of DNS name of the certificate (NULL if none)
</p>
<p><var>names_size</var>: holds the size of the names list
</p>
<p><var>pcert_list</var>: contains a certificate list (path) for the specified private key
</p>
<p><var>pcert_list_size</var>: holds the size of the certificate list
</p>
<p><var>key</var>: is a <code>gnutls_privkey_t</code>  key
</p>
<p>This function sets a certificate/private key pair in the
gnutls_certificate_credentials_t type.  This function may be
called more than once, in case multiple keys/certificates exist for
the server.  For clients that wants to send more than its own end
entity certificate (e.g., also an intermediate CA cert) then put
the certificate chain in  <code>pcert_list</code> . 
</p>
<p>Note that the  <code>pcert_list</code> and  <code>key</code> will become part of the credentials 
structure and must not be deallocated. They will be automatically deallocated 
when the  <code>res</code> type is deinitialized.
</p>
<p>If that function fails to load the  <code>res</code> structure is at an undefined state, it must
not be reused to load other keys or certificates.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<p>If multiple certificates are used with the functions above each
client&rsquo;s request will be served with the certificate that matches the
requested name (see <a href="#Server-name-indication">Server name indication</a>).
</p>
<p>As an alternative to loading from files or buffers, a callback may be used for the 
server or the client to specify the certificate and the key at the handshake time.
In that case a certificate should be selected according the peer&rsquo;s signature
algorithm preferences. To get those preferences use
<a href="#gnutls_005fsign_005falgorithm_005fget_005frequested">gnutls_sign_algorithm_get_requested</a>. Both functions are shown below.
</p>
<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005fcertificate_005fset_005fretrieve_005ffunction">gnutls_certificate_set_retrieve_function</a> (gnutls_certificate_credentials_t <var>cred</var>, gnutls_certificate_retrieve_function * <var>func</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fcertificate_005fset_005fretrieve_005ffunction2">gnutls_certificate_set_retrieve_function2</a> (gnutls_certificate_credentials_t <var>cred</var>, gnutls_certificate_retrieve_function2 * <var>func</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fsign_005falgorithm_005fget_005frequested">gnutls_sign_algorithm_get_requested</a> (gnutls_session_t <var>session</var>, size_t <var>indx</var>, gnutls_sign_algorithm_t * <var>algo</var>)</code></dt>
</dl>
<p>c
The functions above do not handle the requested server name automatically.
A server would need to check the name requested by the client
using <a href="#gnutls_005fserver_005fname_005fget">gnutls_server_name_get</a>, and serve the appropriate
certificate. Note that some of these functions require the <code>gnutls_pcert_st</code> structure to be
filled in. Helper functions to fill in the structure are listed below.
</p>
<pre class="verbatim">typedef struct gnutls_pcert_st
{
  gnutls_pubkey_t pubkey;
  gnutls_datum_t cert;
  gnutls_certificate_type_t type;
} gnutls_pcert_st;
</pre>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpcert_005fimport_005fx509">gnutls_pcert_import_x509</a> (gnutls_pcert_st * <var>pcert</var>, gnutls_x509_crt_t <var>crt</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpcert_005fimport_005fopenpgp">gnutls_pcert_import_openpgp</a> (gnutls_pcert_st * <var>pcert</var>, gnutls_openpgp_crt_t <var>crt</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpcert_005fimport_005fx509_005fraw">gnutls_pcert_import_x509_raw</a> (gnutls_pcert_st * <var>pcert</var>, const gnutls_datum_t * <var>cert</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpcert_005fimport_005fopenpgp_005fraw">gnutls_pcert_import_openpgp_raw</a> (gnutls_pcert_st * <var>pcert</var>, const gnutls_datum_t * <var>cert</var>, gnutls_openpgp_crt_fmt_t <var>format</var>, gnutls_openpgp_keyid_t <var>keyid</var>, unsigned int <var>flags</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fpcert_005fdeinit">gnutls_pcert_deinit</a> (gnutls_pcert_st * <var>pcert</var>)</code></dt>
</dl>

<p>In a handshake, the negotiated cipher suite depends on the
certificate&rsquo;s parameters, so some key exchange methods might not be
available with all certificates. <acronym>GnuTLS</acronym> will disable
ciphersuites that are not compatible with the key, or the enabled
authentication methods.  For example keys marked as sign-only, will
not be able to access the plain RSA ciphersuites, that require
decryption. It is not recommended to use RSA keys for both
signing and encryption. If possible use a different key for the
<code>DHE-RSA</code> which uses signing and <code>RSA</code> that requires decryption.
All the key exchange methods shown in <a href="#tab_003akey_002dexchange">Table 4.1</a> are
available in certificate authentication.
</p>

<a name="Client-certificate-authentication"></a>
<h4 class="subsubheading">Client certificate authentication</h4>

<p>If a certificate is to be requested from the client during the handshake, the server
will send a certificate request message. This behavior is controlled <a href="#gnutls_005fcertificate_005fserver_005fset_005frequest">gnutls_certificate_server_set_request</a>.
The request contains a list of the acceptable by the server certificate signers. This list
is constructed using the trusted certificate authorities of the server.
In cases where the server supports a large number of certificate authorities
it makes sense not to advertise all of the names to save bandwidth. That can
be controlled using the function <a href="#gnutls_005fcertificate_005fsend_005fx509_005frdn_005fsequence">gnutls_certificate_send_x509_rdn_sequence</a>. 
This however will have the side-effect of not restricting the client to certificates
signed by server&rsquo;s acceptable signers.
</p>




<dl>
<dt><a name="index-gnutls_005fcertificate_005fserver_005fset_005frequest"></a>Function: <em>void</em> <strong>gnutls_certificate_server_set_request</strong> <em>(gnutls_session_t <var>session</var>, gnutls_certificate_request_t <var>req</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>req</var>: is one of GNUTLS_CERT_REQUEST, GNUTLS_CERT_REQUIRE
</p>
<p>This function specifies if we (in case of a server) are going to
send a certificate request message to the client. If  <code>req</code> is
GNUTLS_CERT_REQUIRE then the server will return an error if the
peer does not provide a certificate. If you do not call this
function then the client will not be asked to send a certificate.
</p></dd></dl>





<dl>
<dt><a name="index-gnutls_005fcertificate_005fsend_005fx509_005frdn_005fsequence"></a>Function: <em>void</em> <strong>gnutls_certificate_send_x509_rdn_sequence</strong> <em>(gnutls_session_t <var>session</var>, int <var>status</var>)</em></dt>
<dd><p><var>session</var>: a <code>gnutls_session_t</code>  type.
</p>
<p><var>status</var>: is 0 or 1
</p>
<p>If status is non zero, this function will order gnutls not to send
the rdnSequence in the certificate request message. That is the
server will not advertise its trusted CAs to the peer. If status
is zero then the default behaviour will take effect, which is to
advertise the server&rsquo;s trusted CAs.
</p>
<p>This function has no effect in clients, and in authentication
methods other than certificate with X.509 certificates.
</p></dd></dl>


<a name="Client-or-server-certificate-verification"></a>
<h4 class="subsubheading">Client or server certificate verification</h4>

<p>Certificate verification is possible by loading the trusted
authorities into the credentials structure by using
the following functions, applicable to X.509 and OpenPGP certificates.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fx509_005fsystem_005ftrust">gnutls_certificate_set_x509_system_trust</a> (gnutls_certificate_credentials_t       <var>cred</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fx509_005ftrust_005ffile">gnutls_certificate_set_x509_trust_file</a> (gnutls_certificate_credentials_t            <var>cred</var>, const char * <var>cafile</var>, gnutls_x509_crt_fmt_t <var>type</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fset_005fopenpgp_005fkeyring_005ffile">gnutls_certificate_set_openpgp_keyring_file</a> (gnutls_certificate_credentials_t <var>c</var>, const char * <var>file</var>, gnutls_openpgp_crt_fmt_t <var>format</var>)</code></dt>
</dl>

<p>The peer&rsquo;s certificate will be automatically verified if
<a href="#gnutls_005fsession_005fset_005fverify_005fcert">gnutls_session_set_verify_cert</a> is called prior to handshake.
</p>
<p>Alternatively, one must set a callback function during the handshake
using <a href="#gnutls_005fcertificate_005fset_005fverify_005ffunction">gnutls_certificate_set_verify_function</a>, which
will verify the peer&rsquo;s certificate once received. The verification
should happen using <a href="#gnutls_005fcertificate_005fverify_005fpeers3">gnutls_certificate_verify_peers3</a> within
the callback. It will verify the certificate&rsquo;s signature and the owner 
of the certificate. That will provide a brief verification output. If a
detailed output is required one should call <a href="#gnutls_005fcertificate_005fget_005fpeers">gnutls_certificate_get_peers</a>
to obtain the raw certificate of the peer and verify it using the
functions discussed in <a href="#X_002e509-certificates">X.509 certificates</a>.
</p>
<p>In both the automatic and the manual cases, the verification status returned
can be printed using <a href="#gnutls_005fcertificate_005fverification_005fstatus_005fprint">gnutls_certificate_verification_status_print</a>.
</p>




<dl>
<dt><a name="index-gnutls_005fsession_005fset_005fverify_005fcert"></a>Function: <em>void</em> <strong>gnutls_session_set_verify_cert</strong> <em>(gnutls_session_t <var>session</var>, const char * <var>hostname</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p><var>hostname</var>: is the expected name of the peer; may be <code>NULL</code> 
</p>
<p><var>flags</var>: flags for certificate verification &ndash; <code>gnutls_certificate_verify_flags</code> 
</p>
<p>This function instructs GnuTLS to verify the peer&rsquo;s certificate
using the provided hostname. If the verification fails the handshake
will also fail with <code>GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR</code> . In that
case the verification result can be obtained using <code>gnutls_session_get_verify_cert_status()</code> .
</p>
<p>The  <code>hostname</code> pointer provided must remain valid for the lifetime
of the session. More precisely it should be available during any subsequent
handshakes. If no hostname is provided, no hostname verification
will be performed. For a more advanced verification function check
<code>gnutls_session_set_verify_cert2()</code> .
</p>
<p>The <code>gnutls_session_set_verify_cert()</code>  function is intended to be used by TLS
clients to verify the server&rsquo;s certificate.
</p>
<p><strong>Since:</strong> 3.4.6
</p></dd></dl>

<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fverify_005fpeers3">gnutls_certificate_verify_peers3</a> (gnutls_session_t <var>session</var>, const char * <var>hostname</var>, unsigned int * <var>status</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fcertificate_005fset_005fverify_005ffunction">gnutls_certificate_set_verify_function</a> (gnutls_certificate_credentials_t <var>cred</var>, gnutls_certificate_verify_function * <var>func</var>)</code></dt>
</dl>


<hr>
<a name="SRP-credentials"></a>
<div class="header">
<p>
Next: <a href="#PSK-credentials" accesskey="n" rel="next">PSK credentials</a>, Previous: <a href="#Certificate-credentials" accesskey="p" rel="prev">Certificate credentials</a>, Up: <a href="#Associating-the-credentials" accesskey="u" rel="up">Associating the credentials</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="SRP"></a>
<h4 class="subsection">6.4.2 SRP</h4>

<p>The initialization functions in SRP credentials differ between
client and server.
Clients supporting <acronym>SRP</acronym> should set the username and password
prior to connection, to the credentials structure.
Alternatively <a href="#gnutls_005fsrp_005fset_005fclient_005fcredentials_005ffunction">gnutls_srp_set_client_credentials_function</a>
may be used instead, to specify a callback function that should return the
SRP username and password.
The callback is called once during the <acronym>TLS</acronym> handshake.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fsrp_005fallocate_005fserver_005fcredentials">gnutls_srp_allocate_server_credentials</a> (gnutls_srp_server_credentials_t *            <var>sc</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fsrp_005fallocate_005fclient_005fcredentials">gnutls_srp_allocate_client_credentials</a> (gnutls_srp_client_credentials_t *            <var>sc</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fsrp_005ffree_005fserver_005fcredentials">gnutls_srp_free_server_credentials</a> (gnutls_srp_server_credentials_t <var>sc</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fsrp_005ffree_005fclient_005fcredentials">gnutls_srp_free_client_credentials</a> (gnutls_srp_client_credentials_t <var>sc</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fsrp_005fset_005fclient_005fcredentials">gnutls_srp_set_client_credentials</a> (gnutls_srp_client_credentials_t <var>res</var>, const char * <var>username</var>, const char * <var>password</var>)</code></dt>
</dl>





<dl>
<dt><a name="index-gnutls_005fsrp_005fset_005fclient_005fcredentials_005ffunction"></a>Function: <em>void</em> <strong>gnutls_srp_set_client_credentials_function</strong> <em>(gnutls_srp_client_credentials_t         <var>cred</var>, gnutls_srp_client_credentials_function         * <var>func</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_srp_server_credentials_t</code>  type.
</p>
<p><var>func</var>: is the callback function
</p>
<p>This function can be used to set a callback to retrieve the
username and password for client SRP authentication.  The
callback&rsquo;s function form is:
</p>
<p>int (*callback)(gnutls_session_t, char** username, char**password);
</p>
<p>The  <code>username</code> and  <code>password</code> must be allocated using
<code>gnutls_malloc()</code> .   <code>username</code> and  <code>password</code> should be ASCII strings
or UTF-8 strings prepared using the &quot;SASLprep&quot; profile of
&quot;stringprep&quot;.
</p>
<p>The callback function will be called once per handshake before the
initial hello message is sent.
</p>
<p>The callback should not return a negative error code the second
time called, since the handshake procedure will be aborted.
</p>
<p>The callback function should return 0 on success.
-1 indicates an error.
</p></dd></dl>

<p>In server side the default behavior of <acronym>GnuTLS</acronym> is to read
the usernames and <acronym>SRP</acronym> verifiers from password files. These
password file format is compatible the with the <em>Stanford srp libraries</em>
format.  If a different password file format is to be used, then 
<a href="#gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffunction">gnutls_srp_set_server_credentials_function</a> should be called,
to set an appropriate callback. 
</p>




<dl>
<dt><a name="index-gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffile"></a>Function: <em>int</em> <strong>gnutls_srp_set_server_credentials_file</strong> <em>(gnutls_srp_server_credentials_t <var>res</var>, const char * <var>password_file</var>, const char * <var>password_conf_file</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_srp_server_credentials_t</code>  type.
</p>
<p><var>password_file</var>: is the SRP password file (tpasswd)
</p>
<p><var>password_conf_file</var>: is the SRP password conf file (tpasswd.conf)
</p>
<p>This function sets the password files, in a
<code>gnutls_srp_server_credentials_t</code>  type.  Those password files
hold usernames and verifiers and will be used for SRP
authentication.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p></dd></dl>





<dl>
<dt><a name="index-gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffunction"></a>Function: <em>void</em> <strong>gnutls_srp_set_server_credentials_function</strong> <em>(gnutls_srp_server_credentials_t         <var>cred</var>, gnutls_srp_server_credentials_function         * <var>func</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_srp_server_credentials_t</code>  type.
</p>
<p><var>func</var>: is the callback function
</p>
<p>This function can be used to set a callback to retrieve the user&rsquo;s
SRP credentials.  The callback&rsquo;s function form is:
</p>
<p>int (*callback)(gnutls_session_t, const char* username,
gnutls_datum_t *salt, gnutls_datum_t *verifier, gnutls_datum_t *generator,
gnutls_datum_t *prime);
</p>
<p><code>username</code> contains the actual username.
The  <code>salt</code> ,  <code>verifier</code> ,  <code>generator</code> and  <code>prime</code> must be filled
in using the <code>gnutls_malloc()</code> . For convenience  <code>prime</code> and  <code>generator</code> may also be one of the static parameters defined in gnutls.h.
</p>
<p>Initially, the data field is NULL in every <code>gnutls_datum_t</code> 
structure that the callback has to fill in. When the
callback is done GnuTLS deallocates all of those buffers
which are non-NULL, regardless of the return value.
</p>
<p>In order to prevent attackers from guessing valid usernames,
if a user does not exist, g and n values should be filled in
using a random user&rsquo;s parameters. In that case the callback must
return the special value (1).
See <code>gnutls_srp_set_server_fake_salt_seed</code>  too.
If this is not required for your application, return a negative
number from the callback to abort the handshake.
</p>
<p>The callback function will only be called once per handshake.
The callback function should return 0 on success, while
-1 indicates an error.
</p></dd></dl>


<hr>
<a name="PSK-credentials"></a>
<div class="header">
<p>
Next: <a href="#Anonymous-credentials" accesskey="n" rel="next">Anonymous credentials</a>, Previous: <a href="#SRP-credentials" accesskey="p" rel="prev">SRP credentials</a>, Up: <a href="#Associating-the-credentials" accesskey="u" rel="up">Associating the credentials</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="PSK"></a>
<h4 class="subsection">6.4.3 PSK</h4>
<p>The initialization functions in PSK credentials differ between
client and server.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpsk_005fallocate_005fserver_005fcredentials">gnutls_psk_allocate_server_credentials</a> (gnutls_psk_server_credentials_t *            <var>sc</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpsk_005fallocate_005fclient_005fcredentials">gnutls_psk_allocate_client_credentials</a> (gnutls_psk_client_credentials_t *            <var>sc</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fpsk_005ffree_005fserver_005fcredentials">gnutls_psk_free_server_credentials</a> (gnutls_psk_server_credentials_t <var>sc</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fpsk_005ffree_005fclient_005fcredentials">gnutls_psk_free_client_credentials</a> (gnutls_psk_client_credentials_t <var>sc</var>)</code></dt>
</dl>

<p>Clients supporting <acronym>PSK</acronym> should supply the username and key
before a TLS session is established.  Alternatively 
<a href="#gnutls_005fpsk_005fset_005fclient_005fcredentials_005ffunction">gnutls_psk_set_client_credentials_function</a> can be used to
specify a callback function. This has the
advantage that the callback will be called only if <acronym>PSK</acronym> has
been negotiated.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpsk_005fset_005fclient_005fcredentials">gnutls_psk_set_client_credentials</a> (gnutls_psk_client_credentials_t <var>res</var>, const char * <var>username</var>, const gnutls_datum_t * <var>key</var>, gnutls_psk_key_flags <var>flags</var>)</code></dt>
</dl>





<dl>
<dt><a name="index-gnutls_005fpsk_005fset_005fclient_005fcredentials_005ffunction"></a>Function: <em>void</em> <strong>gnutls_psk_set_client_credentials_function</strong> <em>(gnutls_psk_client_credentials_t         <var>cred</var>, gnutls_psk_client_credentials_function         * <var>func</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_psk_server_credentials_t</code>  type.
</p>
<p><var>func</var>: is the callback function
</p>
<p>This function can be used to set a callback to retrieve the username and
password for client PSK authentication.
The callback&rsquo;s function form is:
int (*callback)(gnutls_session_t, char** username,
gnutls_datum_t* key);
</p>
<p>The  <code>username</code> and  <code>key</code> -&gt;data must be allocated using <code>gnutls_malloc()</code> .
 <code>username</code> should be ASCII strings or UTF-8 strings prepared using
the &quot;SASLprep&quot; profile of &quot;stringprep&quot;.
</p>
<p>The callback function will be called once per handshake.
</p>
<p>The callback function should return 0 on success.
-1 indicates an error.
</p></dd></dl>

<p>In server side the default behavior of <acronym>GnuTLS</acronym> is to read
the usernames and <acronym>PSK</acronym> keys from a password file. The
password file should contain usernames and keys in hexadecimal
format. The name of the password file can be stored to the credentials
structure by calling <a href="#gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffile">gnutls_psk_set_server_credentials_file</a>.  If
a different password file format is to be used, then
a callback should be set instead by <a href="#gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffunction">gnutls_psk_set_server_credentials_function</a>.
</p>
<p>The server can help the client chose a suitable username and password,
by sending a hint. Note that there is no common profile for the PSK hint and applications
are discouraged to use it.
A server, may specify the hint by calling
<a href="#gnutls_005fpsk_005fset_005fserver_005fcredentials_005fhint">gnutls_psk_set_server_credentials_hint</a>.  The client can retrieve
the hint, for example in the callback function, using
<a href="#gnutls_005fpsk_005fclient_005fget_005fhint">gnutls_psk_client_get_hint</a>.
</p>




<dl>
<dt><a name="index-gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffile"></a>Function: <em>int</em> <strong>gnutls_psk_set_server_credentials_file</strong> <em>(gnutls_psk_server_credentials_t            <var>res</var>, const char * <var>password_file</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_psk_server_credentials_t</code>  type.
</p>
<p><var>password_file</var>: is the PSK password file (passwd.psk)
</p>
<p>This function sets the password file, in a
<code>gnutls_psk_server_credentials_t</code>  type.  This password file
holds usernames and keys and will be used for PSK authentication.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffunction">gnutls_psk_set_server_credentials_function</a> (gnutls_psk_server_credentials_t         <var>cred</var>, gnutls_psk_server_credentials_function         * <var>func</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpsk_005fset_005fserver_005fcredentials_005fhint">gnutls_psk_set_server_credentials_hint</a> (gnutls_psk_server_credentials_t <var>res</var>, const char * <var>hint</var>)</code></dt>
<dt><code><var>const char *</var> <a href="#gnutls_005fpsk_005fclient_005fget_005fhint">gnutls_psk_client_get_hint</a> (gnutls_session_t <var>session</var>)</code></dt>
</dl>

<hr>
<a name="Anonymous-credentials"></a>
<div class="header">
<p>
Previous: <a href="#PSK-credentials" accesskey="p" rel="prev">PSK credentials</a>, Up: <a href="#Associating-the-credentials" accesskey="u" rel="up">Associating the credentials</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Anonymous"></a>
<h4 class="subsection">6.4.4 Anonymous</h4>
<p>The key exchange methods for anonymous authentication
might require Diffie-Hellman parameters to be generated by the server and
associated with an anonymous credentials structure. Check
<a href="#Parameter-generation">Parameter generation</a> for more information.
The initialization functions for the credentials are shown below.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fanon_005fallocate_005fserver_005fcredentials">gnutls_anon_allocate_server_credentials</a> (gnutls_anon_server_credentials_t *      <var>sc</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fanon_005fallocate_005fclient_005fcredentials">gnutls_anon_allocate_client_credentials</a> (gnutls_anon_client_credentials_t *      <var>sc</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fanon_005ffree_005fserver_005fcredentials">gnutls_anon_free_server_credentials</a> (gnutls_anon_server_credentials_t <var>sc</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fanon_005ffree_005fclient_005fcredentials">gnutls_anon_free_client_credentials</a> (gnutls_anon_client_credentials_t <var>sc</var>)</code></dt>
</dl>



<hr>
<a name="Setting-up-the-transport-layer"></a>
<div class="header">
<p>
Next: <a href="#TLS-handshake" accesskey="n" rel="next">TLS handshake</a>, Previous: <a href="#Associating-the-credentials" accesskey="p" rel="prev">Associating the credentials</a>, Up: <a href="#How-to-use-GnuTLS-in-applications" accesskey="u" rel="up">How to use GnuTLS in applications</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Setting-up-the-transport-layer-1"></a>
<h3 class="section">6.5 Setting up the transport layer</h3>

<p>The next step is to setup the underlying transport layer details. The
Berkeley sockets are implicitly used by GnuTLS, thus a
call to <a href="#gnutls_005ftransport_005fset_005fint">gnutls_transport_set_int</a> would be sufficient to
specify the socket descriptor. 
</p>
<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005ftransport_005fset_005fint">gnutls_transport_set_int</a> (gnutls_session_t <var>session</var>, int <var>i</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005ftransport_005fset_005fint2">gnutls_transport_set_int2</a> (gnutls_session_t <var>session</var>, int <var>recv_int</var>, int <var>send_int</var>)</code></dt>
</dl>

<p>If however another transport layer than TCP is selected, then
a pointer should be used instead to express the parameter to be
passed to custom functions. In that case the following functions should
be used instead.
</p>
<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005ftransport_005fset_005fptr">gnutls_transport_set_ptr</a> (gnutls_session_t <var>session</var>, gnutls_transport_ptr_t <var>ptr</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005ftransport_005fset_005fptr2">gnutls_transport_set_ptr2</a> (gnutls_session_t <var>session</var>, gnutls_transport_ptr_t <var>recv_ptr</var>, gnutls_transport_ptr_t <var>send_ptr</var>)</code></dt>
</dl>

<p>Moreover all of the following push and pull callbacks should be set.
</p>




<dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fpush_005ffunction"></a>Function: <em>void</em> <strong>gnutls_transport_set_push_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_push_func <var>push_func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>push_func</var>: a callback function similar to <code>write()</code> 
</p>
<p>This is the function where you set a push function for gnutls to
use in order to send data.  If you are going to use berkeley style
sockets, you do not need to use this function since the default
send(2) will probably be ok.  Otherwise you should specify this
function for gnutls to be able to send data.
The callback should return a positive number indicating the
bytes sent, and -1 on error.
</p>
<p><code>push_func</code> is of the form,
ssize_t (*gnutls_push_func)(gnutls_transport_ptr_t, const void*, size_t);
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fvec_005fpush_005ffunction"></a>Function: <em>void</em> <strong>gnutls_transport_set_vec_push_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_vec_push_func <var>vec_func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>vec_func</var>: a callback function similar to <code>writev()</code> 
</p>
<p>Using this function you can override the default writev(2)
function for gnutls to send data. Setting this callback 
instead of <code>gnutls_transport_set_push_function()</code>  is recommended
since it introduces less overhead in the TLS handshake process.
</p>
<p><code>vec_func</code> is of the form,
ssize_t (*gnutls_vec_push_func) (gnutls_transport_ptr_t, const giovec_t * iov, int iovcnt);
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fpull_005ffunction"></a>Function: <em>void</em> <strong>gnutls_transport_set_pull_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_pull_func <var>pull_func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>pull_func</var>: a callback function similar to <code>read()</code> 
</p>
<p>This is the function where you set a function for gnutls to receive
data.  Normally, if you use berkeley style sockets, do not need to
use this function since the default recv(2) will probably be ok.
The callback should return 0 on connection termination, a positive
number indicating the number of bytes received, and -1 on error.
</p>
<p><code>gnutls_pull_func</code> is of the form,
ssize_t (*gnutls_pull_func)(gnutls_transport_ptr_t, void*, size_t);
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fpull_005ftimeout_005ffunction"></a>Function: <em>void</em> <strong>gnutls_transport_set_pull_timeout_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_pull_timeout_func <var>func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>func</var>: a callback function
</p>
<p>This is the function where you set a function for gnutls to know
whether data are ready to be received. It should wait for data a
given time frame in milliseconds. The callback should return 0 on 
timeout, a positive number if data can be received, and -1 on error.
You&rsquo;ll need to override this function if <code>select()</code>  is not suitable
for the provided transport calls.
</p>
<p>As with <code>select()</code> , if the timeout value is zero the callback should return
zero if no data are immediately available.
</p>
<p><code>gnutls_pull_timeout_func</code> is of the form,
int (*gnutls_pull_timeout_func)(gnutls_transport_ptr_t, unsigned int ms);
</p>
<p>This callback is necessary when <code>gnutls_handshake_set_timeout()</code>  or 
<code>gnutls_record_set_timeout()</code>  are set. It will not be used when 
non-blocking sockets are in use. That is, this function will
not operate when <code>GNUTLS_NONBLOCK</code>  is specified in <code>gnutls_init()</code> , 
or a custom pull function is registered without updating the 
pull timeout function.
</p>
<p>The helper function <code>gnutls_system_recv_timeout()</code>  is provided to
simplify writing callbacks. 
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>


<p>The functions above accept a callback function which
should return the number of bytes written, or -1 on
error and should set <code>errno</code> appropriately.
In some environments, setting <code>errno</code> is unreliable. For example
Windows have several errno variables in different CRTs, or in other
systems it may be a non thread-local variable.  If this is a concern to
you, call <a href="#gnutls_005ftransport_005fset_005ferrno">gnutls_transport_set_errno</a> with the intended errno
value instead of setting <code>errno</code> directly.
</p>




<dl>
<dt><a name="index-gnutls_005ftransport_005fset_005ferrno"></a>Function: <em>void</em> <strong>gnutls_transport_set_errno</strong> <em>(gnutls_session_t <var>session</var>, int <var>err</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>err</var>: error value to store in session-specific errno variable.
</p>
<p>Store  <code>err</code> in the session-specific errno variable.  Useful values
for  <code>err</code> are EINTR, EAGAIN and EMSGSIZE, other values are treated will be
treated as real errors in the push/pull function.
</p>
<p>This function is useful in replacement push and pull functions set by
<code>gnutls_transport_set_push_function()</code>  and
<code>gnutls_transport_set_pull_function()</code>  under Windows, where the
replacements may not have access to the same  <code>errno</code> variable that is used by GnuTLS (e.g., the application is linked to
msvcr71.dll and gnutls is linked to msvcrt.dll).
</p></dd></dl>

<p><acronym>GnuTLS</acronym> currently only interprets the EINTR, EAGAIN and EMSGSIZE errno
values and returns the corresponding <acronym>GnuTLS</acronym> error codes:
</p><ul>
<li> <code>GNUTLS_E_INTERRUPTED</code> 
</li><li> <code>GNUTLS_E_AGAIN</code>
</li><li> <code>GNUTLS_E_LARGE_PACKET</code>
</li></ul>
<p>The EINTR and EAGAIN values are returned by interrupted system calls, 
or when non blocking IO is used.  All <acronym>GnuTLS</acronym> functions can be 
resumed (called again), if any of the above error codes is returned. The
EMSGSIZE value is returned when attempting to send a large datagram.
</p>
<p>In the case of DTLS it is also desirable to override the generic 
transport functions with functions that emulate the operation
of <code>recvfrom</code> and <code>sendto</code>. In addition
<acronym>DTLS</acronym> requires timers during the receive of a handshake
message, set using the <a href="#gnutls_005ftransport_005fset_005fpull_005ftimeout_005ffunction">gnutls_transport_set_pull_timeout_function</a> 
function. To check the retransmission timers the function
<a href="#gnutls_005fdtls_005fget_005ftimeout">gnutls_dtls_get_timeout</a> is provided, which returns the time
remaining until the next retransmission, or better the time until 
<a href="#gnutls_005fhandshake">gnutls_handshake</a> should be called again.
</p>




<dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fpull_005ftimeout_005ffunction-1"></a>Function: <em>void</em> <strong>gnutls_transport_set_pull_timeout_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_pull_timeout_func <var>func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>func</var>: a callback function
</p>
<p>This is the function where you set a function for gnutls to know
whether data are ready to be received. It should wait for data a
given time frame in milliseconds. The callback should return 0 on 
timeout, a positive number if data can be received, and -1 on error.
You&rsquo;ll need to override this function if <code>select()</code>  is not suitable
for the provided transport calls.
</p>
<p>As with <code>select()</code> , if the timeout value is zero the callback should return
zero if no data are immediately available.
</p>
<p><code>gnutls_pull_timeout_func</code> is of the form,
int (*gnutls_pull_timeout_func)(gnutls_transport_ptr_t, unsigned int ms);
</p>
<p>This callback is necessary when <code>gnutls_handshake_set_timeout()</code>  or 
<code>gnutls_record_set_timeout()</code>  are set. It will not be used when 
non-blocking sockets are in use. That is, this function will
not operate when <code>GNUTLS_NONBLOCK</code>  is specified in <code>gnutls_init()</code> , 
or a custom pull function is registered without updating the 
pull timeout function.
</p>
<p>The helper function <code>gnutls_system_recv_timeout()</code>  is provided to
simplify writing callbacks. 
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fdtls_005fget_005ftimeout"></a>Function: <em>unsigned int</em> <strong>gnutls_dtls_get_timeout</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function will return the milliseconds remaining
for a retransmission of the previously sent handshake
message. This function is useful when DTLS is used in
non-blocking mode, to estimate when to call <code>gnutls_handshake()</code> 
if no packets have been received.
</p>
<p><strong>Returns:</strong> the remaining time in milliseconds.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Asynchronous-operation" accesskey="1">Asynchronous operation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#DTLS-sessions" accesskey="2">DTLS sessions</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Asynchronous-operation"></a>
<div class="header">
<p>
Next: <a href="#DTLS-sessions" accesskey="n" rel="next">DTLS sessions</a>, Up: <a href="#Setting-up-the-transport-layer" accesskey="u" rel="up">Setting up the transport layer</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Asynchronous-operation-1"></a>
<h4 class="subsection">6.5.1 Asynchronous operation</h4>

<p><acronym>GnuTLS</acronym> can be used with asynchronous socket or event-driven programming.
The approach is similar to using Berkeley sockets under such an environment.
The blocking, due to network interaction, calls such as
<a href="#gnutls_005fhandshake">gnutls_handshake</a>, <a href="#gnutls_005frecord_005frecv">gnutls_record_recv</a>,
can be set to non-blocking by setting the underlying sockets to non-blocking.
If other push and pull functions are setup, then they should behave the same
way as <code>recv</code> and <code>send</code> when used in a non-blocking
way, i.e., set errno to <code>EAGAIN</code>. Since, during a TLS protocol session 
<acronym>GnuTLS</acronym> does not block except for network interaction, the non blocking
<code>EAGAIN</code> errno will be propagated and <acronym>GnuTLS</acronym> functions 
will return the <code>GNUTLS_E_AGAIN</code> error code. Such calls can be resumed the 
same way as a system call would. 
The only exception is <a href="#gnutls_005frecord_005fsend">gnutls_record_send</a>,
which if interrupted subsequent calls need not to include the data to be
sent (can be called with NULL argument).
</p>
<p>When using the <code>select</code> system call though, one should remember
that it is only applicable to the kernel sockets API. To check for any
available buffers in a <acronym>GnuTLS</acronym> session, 
utilize <a href="#gnutls_005frecord_005fcheck_005fpending">gnutls_record_check_pending</a>,
either before the <code>select</code> system call, or after a call to
<a href="#gnutls_005frecord_005frecv">gnutls_record_recv</a>. <acronym>GnuTLS</acronym> does not keep a write buffer,
thus when writing no additional actions are required.
</p>
<p>The following paragraphs describe the detailed requirements for non-blocking
operation when using the TLS or DTLS protocols.
</p>
<a name="TLS-protocol"></a>
<h4 class="subsubsection">6.5.1.1 TLS protocol</h4>
<p>There are no special requirements for the TLS protocol operation in non-blocking
mode if a non-blocking socket is used.
</p>
<p>It is recommended, however, for future compatibility, when in non-blocking mode, to
call the <a href="#gnutls_005finit">gnutls_init</a> function with the
<code>GNUTLS_NONBLOCK</code> flag set (see <a href="#Session-initialization">Session initialization</a>).
</p>
<a name="Datagram-TLS-protocol"></a>
<h4 class="subsubsection">6.5.1.2 Datagram TLS protocol</h4>
<p>When in non-blocking mode the function, the <a href="#gnutls_005finit">gnutls_init</a> function 
must be called with the <code>GNUTLS_NONBLOCK</code> flag set (see <a href="#Session-initialization">Session initialization</a>). 
</p>
<p>In constrast with the TLS protocol, the pull timeout function is required,
but will only be called with a timeout of zero. In that case it should indicate
whether there are data to be received or not. When not using the default pull function,
then <a href="#gnutls_005ftransport_005fset_005fpull_005ftimeout_005ffunction">gnutls_transport_set_pull_timeout_function</a> should be called.
</p>
<p>Although in the TLS protocol implementation each call to receive or send
function implies to restoring the same function that was interrupted, in
the DTLS protocol this requirement isn&rsquo;t true.
There are cases where a retransmission is required, which are indicated by
a received message and thus <a href="#gnutls_005frecord_005fget_005fdirection">gnutls_record_get_direction</a> must be called 
to decide which direction to check prior to restoring a function call.
</p>



<dl>
<dt><a name="index-gnutls_005frecord_005fget_005fdirection"></a>Function: <em>int</em> <strong>gnutls_record_get_direction</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function provides information about the internals of the
record protocol and is only useful if a prior gnutls function call
(e.g.  <code>gnutls_handshake()</code> ) was interrupted for some reason, that
is, if a function returned <code>GNUTLS_E_INTERRUPTED</code>  or
<code>GNUTLS_E_AGAIN</code> .  In such a case, you might want to call <code>select()</code> 
or <code>poll()</code>  before calling the interrupted gnutls function again.  To
tell you whether a file descriptor should be selected for either
reading or writing, <code>gnutls_record_get_direction()</code>  returns 0 if the
interrupted function was trying to read data, and 1 if it was
trying to write data.
</p>
<p>This function&rsquo;s output is unreliable if you are using the
 <code>session</code> in different threads, for sending and receiving.
</p>
<p><strong>Returns:</strong> 0 if trying to read data, 1 if trying to write data.
</p></dd></dl>

<p>When calling <a href="#gnutls_005fhandshake">gnutls_handshake</a> through a multi-plexer,
to be able to handle properly the DTLS handshake retransmission timers,
the function <a href="#gnutls_005fdtls_005fget_005ftimeout">gnutls_dtls_get_timeout</a>
should be used to estimate when to call <a href="#gnutls_005fhandshake">gnutls_handshake</a> if
no data have been received.
</p>
<hr>
<a name="DTLS-sessions"></a>
<div class="header">
<p>
Previous: <a href="#Asynchronous-operation" accesskey="p" rel="prev">Asynchronous operation</a>, Up: <a href="#Setting-up-the-transport-layer" accesskey="u" rel="up">Setting up the transport layer</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="DTLS-sessions-1"></a>
<h4 class="subsection">6.5.2 DTLS sessions</h4>

<p>Because datagram TLS can operate over connections where the client
cannot be reliably verified, functionality in the form of cookies, is available to prevent
denial of service attacks to servers. <acronym>GnuTLS</acronym> requires a server
to generate a secret key that is used to sign a cookie<a name="DOCF16" href="#FOOT16"><sup>16</sup></a>. 
That cookie is sent to the client using <a href="#gnutls_005fdtls_005fcookie_005fsend">gnutls_dtls_cookie_send</a>, and 
the client must reply using the correct cookie. The server side
should verify the initial message sent by client using <a href="#gnutls_005fdtls_005fcookie_005fverify">gnutls_dtls_cookie_verify</a>.
If successful the session should be initialized and associated with
the cookie using <a href="#gnutls_005fdtls_005fprestate_005fset">gnutls_dtls_prestate_set</a>, before proceeding to
the handshake.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fkey_005fgenerate">gnutls_key_generate</a> (gnutls_datum_t * <var>key</var>, unsigned int <var>key_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fdtls_005fcookie_005fsend">gnutls_dtls_cookie_send</a> (gnutls_datum_t * <var>key</var>, void * <var>client_data</var>, size_t <var>client_data_size</var>, gnutls_dtls_prestate_st * <var>prestate</var>, gnutls_transport_ptr_t <var>ptr</var>, gnutls_push_func <var>push_func</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fdtls_005fcookie_005fverify">gnutls_dtls_cookie_verify</a> (gnutls_datum_t * <var>key</var>, void * <var>client_data</var>, size_t <var>client_data_size</var>, void * <var>_msg</var>, size_t <var>msg_size</var>, gnutls_dtls_prestate_st * <var>prestate</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fdtls_005fprestate_005fset">gnutls_dtls_prestate_set</a> (gnutls_session_t <var>session</var>, gnutls_dtls_prestate_st * <var>prestate</var>)</code></dt>
</dl>

<p>Note that the above apply to server side only and they are not mandatory to be
used. Not using them, however, allows denial of service attacks.
The client side cookie handling is part of <a href="#gnutls_005fhandshake">gnutls_handshake</a>. 
</p>
<p>Datagrams are typically restricted by a maximum transfer unit (MTU). For that
both client and server side should set the correct maximum transfer unit for
the layer underneath <acronym>GnuTLS</acronym>. This will allow proper fragmentation
of DTLS messages and prevent messages from being silently discarded by the
transport layer. The &ldquo;correct&rdquo; maximum transfer unit can be obtained through
a path MTU discovery mechanism [<em>RFC4821</em>].
</p>
<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005fdtls_005fset_005fmtu">gnutls_dtls_set_mtu</a> (gnutls_session_t <var>session</var>, unsigned int <var>mtu</var>)</code></dt>
<dt><code><var>unsigned int</var> <a href="#gnutls_005fdtls_005fget_005fmtu">gnutls_dtls_get_mtu</a> (gnutls_session_t <var>session</var>)</code></dt>
<dt><code><var>unsigned int</var> <a href="#gnutls_005fdtls_005fget_005fdata_005fmtu">gnutls_dtls_get_data_mtu</a> (gnutls_session_t <var>session</var>)</code></dt>
</dl>


<hr>
<a name="TLS-handshake"></a>
<div class="header">
<p>
Next: <a href="#Data-transfer-and-termination" accesskey="n" rel="next">Data transfer and termination</a>, Previous: <a href="#Setting-up-the-transport-layer" accesskey="p" rel="prev">Setting up the transport layer</a>, Up: <a href="#How-to-use-GnuTLS-in-applications" accesskey="u" rel="up">How to use GnuTLS in applications</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="TLS-handshake-1"></a>
<h3 class="section">6.6 TLS handshake</h3>
<p>Once a session has been initialized and a network
connection has been set up, TLS and DTLS protocols
perform a handshake. The handshake is the actual key
exchange.
</p>




<dl>
<dt><a name="index-gnutls_005fhandshake"></a>Function: <em>int</em> <strong>gnutls_handshake</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function does the handshake of the TLS/SSL protocol, and
initializes the TLS connection.
</p>
<p>This function will fail if any problem is encountered, and will
return a negative error code. In case of a client, if the client
has asked to resume a session, but the server couldn&rsquo;t, then a
full handshake will be performed.
</p>
<p>The non-fatal errors expected by this function are:
<code>GNUTLS_E_INTERRUPTED</code> , <code>GNUTLS_E_AGAIN</code> , 
<code>GNUTLS_E_WARNING_ALERT_RECEIVED</code> , and <code>GNUTLS_E_GOT_APPLICATION_DATA</code> ,
the latter only in a case of rehandshake.
</p>
<p>The former two interrupt the handshake procedure due to the lower
layer being interrupted, and the latter because of an alert that
may be sent by a server (it is always a good idea to check any
received alerts). On these errors call this function again, until it
returns 0; cf.  <code>gnutls_record_get_direction()</code>  and
<code>gnutls_error_is_fatal()</code> . In DTLS sessions the non-fatal error
<code>GNUTLS_E_LARGE_PACKET</code>  is also possible, and indicates that
the MTU should be adjusted.
</p>
<p>If this function is called by a server after a rehandshake request
then <code>GNUTLS_E_GOT_APPLICATION_DATA</code>  or
<code>GNUTLS_E_WARNING_ALERT_RECEIVED</code>  may be returned.  Note that these
are non fatal errors, only in the specific case of a rehandshake.
Their meaning is that the client rejected the rehandshake request or
in the case of <code>GNUTLS_E_GOT_APPLICATION_DATA</code>  it could also mean that
some data were pending. A client may receive that error code if
it initiates the handshake and the server doesn&rsquo;t agreed.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p></dd></dl>





<dl>
<dt><a name="index-gnutls_005fhandshake_005fset_005ftimeout"></a>Function: <em>void</em> <strong>gnutls_handshake_set_timeout</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>ms</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>ms</var>: is a timeout value in milliseconds
</p>
<p>This function sets the timeout for the TLS handshake process
to the provided value. Use an  <code>ms</code> value of zero to disable
timeout, or <code>GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT</code>  for a reasonable
default value. For the DTLS protocol, the more detailed
<code>gnutls_dtls_set_timeouts()</code>  is provided.
</p>
<p>This function requires to set a pull timeout callback. See
<code>gnutls_transport_set_pull_timeout_function()</code> .
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<p>In GnuTLS 3.5.0 and later it is recommended to use <a href="#gnutls_005fsession_005fset_005fverify_005fcert">gnutls_session_set_verify_cert</a>
for the handshake process to ensure the verification of the peer&rsquo;s identity.
</p>
<p>In older GnuTLS versions it is required to manually verify the peer&rsquo;s certificate
during the handshake by using <a href="#gnutls_005fcertificate_005fset_005fverify_005ffunction">gnutls_certificate_set_verify_function</a>, and
<a href="#gnutls_005fcertificate_005fverify_005fpeers2">gnutls_certificate_verify_peers2</a>. See <a href="#Certificate-authentication">Certificate authentication</a>
for more information.
</p>
<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005fsession_005fset_005fverify_005fcert">gnutls_session_set_verify_cert</a> (gnutls_session_t <var>session</var>, const char * <var>hostname</var>, unsigned <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcertificate_005fverify_005fpeers2">gnutls_certificate_verify_peers2</a> (gnutls_session_t <var>session</var>, unsigned int * <var>status</var>)</code></dt>
</dl>

<hr>
<a name="Data-transfer-and-termination"></a>
<div class="header">
<p>
Next: <a href="#Buffered-data-transfer" accesskey="n" rel="next">Buffered data transfer</a>, Previous: <a href="#TLS-handshake" accesskey="p" rel="prev">TLS handshake</a>, Up: <a href="#How-to-use-GnuTLS-in-applications" accesskey="u" rel="up">How to use GnuTLS in applications</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Data-transfer-and-termination-1"></a>
<h3 class="section">6.7 Data transfer and termination</h3>
<p>Once the handshake is complete and peer&rsquo;s identity
has been verified data can be exchanged. The available
functions resemble the POSIX <code>recv</code> and <code>send</code>
functions. It is suggested to use <a href="#gnutls_005ferror_005fis_005ffatal">gnutls_error_is_fatal</a>
to check whether the error codes returned by these functions are
fatal for the protocol or can be ignored.
</p>




<dl>
<dt><a name="index-gnutls_005frecord_005fsend"></a>Function: <em>ssize_t</em> <strong>gnutls_record_send</strong> <em>(gnutls_session_t <var>session</var>, const void * <var>data</var>, size_t <var>data_size</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>data</var>: contains the data to send
</p>
<p><var>data_size</var>: is the length of the data
</p>
<p>This function has the similar semantics with <code>send()</code> .  The only
difference is that it accepts a GnuTLS session, and uses different
error codes.
Note that if the send buffer is full, <code>send()</code>  will block this
function.  See the <code>send()</code>  documentation for more information.  
</p>
<p>You can replace the default push function which is <code>send()</code> , by using
<code>gnutls_transport_set_push_function()</code> .
</p>
<p>If the EINTR is returned by the internal push function 
then <code>GNUTLS_E_INTERRUPTED</code>  will be returned. If
<code>GNUTLS_E_INTERRUPTED</code>  or <code>GNUTLS_E_AGAIN</code>  is returned, you must
call this function again, with the exact same parameters; alternatively
you could provide a <code>NULL</code>  pointer for data, and 0 for
size. cf. <code>gnutls_record_get_direction()</code> . 
</p>
<p>Note that in DTLS this function will return the <code>GNUTLS_E_LARGE_PACKET</code> 
error code if the send data exceed the data MTU value - as returned
by <code>gnutls_dtls_get_data_mtu()</code> . The errno value EMSGSIZE
also maps to <code>GNUTLS_E_LARGE_PACKET</code> . 
Note that since 3.2.13 this function can be called under cork in DTLS
mode, and will refuse to send data over the MTU size by returning
<code>GNUTLS_E_LARGE_PACKET</code> .
</p>
<p><strong>Returns:</strong> The number of bytes sent, or a negative error code.  The
number of bytes sent might be less than  <code>data_size</code> .  The maximum
number of bytes this function can send in a single call depends
on the negotiated maximum record size.
</p></dd></dl>





<dl>
<dt><a name="index-gnutls_005frecord_005frecv"></a>Function: <em>ssize_t</em> <strong>gnutls_record_recv</strong> <em>(gnutls_session_t <var>session</var>, void * <var>data</var>, size_t <var>data_size</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>data</var>: the buffer that the data will be read into
</p>
<p><var>data_size</var>: the number of requested bytes
</p>
<p>This function has the similar semantics with <code>recv()</code> .  The only
difference is that it accepts a GnuTLS session, and uses different
error codes.
In the special case that the peer requests a renegotiation, the
caller will receive an error code of <code>GNUTLS_E_REHANDSHAKE</code> .  In case
of a client, this message may be simply ignored, replied with an alert
<code>GNUTLS_A_NO_RENEGOTIATION</code> , or replied with a new handshake,
depending on the client&rsquo;s will. A server receiving this error code
can only initiate a new handshake or terminate the session.
</p>
<p>If <code>EINTR</code>  is returned by the internal push function (the default
is <code>recv()</code> ) then <code>GNUTLS_E_INTERRUPTED</code>  will be returned.  If
<code>GNUTLS_E_INTERRUPTED</code>  or <code>GNUTLS_E_AGAIN</code>  is returned, you must
call this function again to get the data.  See also
<code>gnutls_record_get_direction()</code> .
</p>
<p><strong>Returns:</strong> The number of bytes received and zero on EOF (for stream
connections).  A negative error code is returned in case of an error.  
The number of bytes received might be less than the requested  <code>data_size</code> .
</p></dd></dl>





<dl>
<dt><a name="index-gnutls_005ferror_005fis_005ffatal"></a>Function: <em>int</em> <strong>gnutls_error_is_fatal</strong> <em>(int <var>error</var>)</em></dt>
<dd><p><var>error</var>: is a GnuTLS error code, a negative error code
</p>
<p>If a GnuTLS function returns a negative error code you may feed that
value to this function to see if the error condition is fatal to
a TLS session (i.e., must be terminated). 
</p>
<p>Note that you may also want to check the error code manually, since some
non-fatal errors to the protocol (such as a warning alert or
a rehandshake request) may be fatal for your program.
</p>
<p>This function is only useful if you are dealing with errors from
functions that relate to a TLS session (e.g., record layer or handshake 
layer handling functions).
</p>
<p><strong>Returns:</strong> Non-zero value on fatal errors or zero on non-fatal.
</p></dd></dl>

<p>Although, in the TLS protocol the receive function can be called
at any time, when DTLS is used the GnuTLS receive functions must be
called once a message is available for reading, even if no data are
expected. This is because in DTLS various (internal) actions
may be required due to retransmission timers. Moreover,
an extended receive function is shown below, which allows the extraction
of the message&rsquo;s sequence number. Due to the unreliable nature of the
protocol, this field allows distinguishing out-of-order messages.
</p>




<dl>
<dt><a name="index-gnutls_005frecord_005frecv_005fseq"></a>Function: <em>ssize_t</em> <strong>gnutls_record_recv_seq</strong> <em>(gnutls_session_t <var>session</var>, void * <var>data</var>, size_t <var>data_size</var>, unsigned char * <var>seq</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>data</var>: the buffer that the data will be read into
</p>
<p><var>data_size</var>: the number of requested bytes
</p>
<p><var>seq</var>: is the packet&rsquo;s 64-bit sequence number. Should have space for 8 bytes.
</p>
<p>This function is the same as <code>gnutls_record_recv()</code> , except that
it returns in addition to data, the sequence number of the data.
This is useful in DTLS where record packets might be received
out-of-order. The returned 8-byte sequence number is an
integer in big-endian format and should be
treated as a unique message identification. 
</p>
<p><strong>Returns:</strong> The number of bytes received and zero on EOF.  A negative
error code is returned in case of an error.  The number of bytes
received might be less than  <code>data_size</code> .
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<p>The <a href="#gnutls_005frecord_005fcheck_005fpending">gnutls_record_check_pending</a> helper function is available to 
allow checking whether data are available to be read in a <acronym>GnuTLS</acronym> session 
buffers. Note that this function complements but does not replace <code>select</code>,
i.e., <a href="#gnutls_005frecord_005fcheck_005fpending">gnutls_record_check_pending</a> reports no data to be read, <code>select</code>
should be called to check for data in the network buffers.
</p>




<dl>
<dt><a name="index-gnutls_005frecord_005fcheck_005fpending"></a>Function: <em>size_t</em> <strong>gnutls_record_check_pending</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function checks if there are unread data
in the gnutls buffers. If the return value is
non-zero the next call to <code>gnutls_record_recv()</code> 
is guaranteed not to block.
</p>
<p><strong>Returns:</strong> Returns the size of the data or zero.
</p></dd></dl>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005frecord_005fget_005fdirection">gnutls_record_get_direction</a> (gnutls_session_t <var>session</var>)</code></dt>
</dl>

<p>Once a TLS or DTLS session is no longer needed, it is
recommended to use <a href="#gnutls_005fbye">gnutls_bye</a> to terminate the
session. That way the peer is notified securely about the
intention of termination, which allows distinguishing it
from a malicious connection termination.
A session can be deinitialized with the <a href="#gnutls_005fdeinit">gnutls_deinit</a> function.
</p>




<dl>
<dt><a name="index-gnutls_005fbye"></a>Function: <em>int</em> <strong>gnutls_bye</strong> <em>(gnutls_session_t <var>session</var>, gnutls_close_request_t <var>how</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>how</var>: is an integer
</p>
<p>Terminates the current TLS/SSL connection. The connection should
have been initiated using <code>gnutls_handshake()</code> .   <code>how</code> should be one
of <code>GNUTLS_SHUT_RDWR</code> , <code>GNUTLS_SHUT_WR</code> .
</p>
<p>In case of <code>GNUTLS_SHUT_RDWR</code>  the TLS session gets
terminated and further receives and sends will be disallowed.  If
the return value is zero you may continue using the underlying
transport layer. <code>GNUTLS_SHUT_RDWR</code>  sends an alert containing a close
request and waits for the peer to reply with the same message.
</p>
<p>In case of <code>GNUTLS_SHUT_WR</code>  the TLS session gets terminated
and further sends will be disallowed. In order to reuse the
connection you should wait for an EOF from the peer.
<code>GNUTLS_SHUT_WR</code>  sends an alert containing a close request.
</p>
<p>Note that not all implementations will properly terminate a TLS
connection.  Some of them, usually for performance reasons, will
terminate only the underlying transport layer, and thus not
distinguishing between a malicious party prematurely terminating 
the connection and normal termination. 
</p>
<p>This function may also return <code>GNUTLS_E_AGAIN</code>  or
<code>GNUTLS_E_INTERRUPTED</code> ; cf.  <code>gnutls_record_get_direction()</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code, see
function documentation for entire semantics.
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_deinit</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function clears all buffers associated with the  <code>session</code> .
This function will also remove session data from the session
database if the session was terminated abnormally.
</p></dd></dl>

<hr>
<a name="Buffered-data-transfer"></a>
<div class="header">
<p>
Next: <a href="#Handling-alerts" accesskey="n" rel="next">Handling alerts</a>, Previous: <a href="#Data-transfer-and-termination" accesskey="p" rel="prev">Data transfer and termination</a>, Up: <a href="#How-to-use-GnuTLS-in-applications" accesskey="u" rel="up">How to use GnuTLS in applications</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Buffered-data-transfer-1"></a>
<h3 class="section">6.8 Buffered data transfer</h3>

<p>Although <a href="#gnutls_005frecord_005fsend">gnutls_record_send</a> is sufficient to transmit data
to the peer, when many small chunks of data are to be transmitted
it is inefficient and wastes bandwidth due to the TLS record
overhead. In that case it is preferrable to combine the small chunks
before transmission. The following functions provide that functionality.
</p>




<dl>
<dt><a name="index-gnutls_005frecord_005fcork"></a>Function: <em>void</em> <strong>gnutls_record_cork</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>If called, <code>gnutls_record_send()</code>  will no longer send any records.
Any sent records will be cached until <code>gnutls_record_uncork()</code>  is called.
</p>
<p>This function is safe to use with DTLS after GnuTLS 3.3.0.
</p>
<p><strong>Since:</strong> 3.1.9
</p></dd></dl>





<dl>
<dt><a name="index-gnutls_005frecord_005funcork"></a>Function: <em>int</em> <strong>gnutls_record_uncork</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>flags</var>: Could be zero or <code>GNUTLS_RECORD_WAIT</code> 
</p>
<p>This resets the effect of <code>gnutls_record_cork()</code> , and flushes any pending
data. If the <code>GNUTLS_RECORD_WAIT</code>  flag is specified then this
function will block until the data is sent or a fatal error
occurs (i.e., the function will retry on <code>GNUTLS_E_AGAIN</code>  and
<code>GNUTLS_E_INTERRUPTED</code> ).
</p>
<p>If the flag <code>GNUTLS_RECORD_WAIT</code>  is not specified and the function
is interrupted then the <code>GNUTLS_E_AGAIN</code>  or <code>GNUTLS_E_INTERRUPTED</code> 
errors will be returned. To obtain the data left in the corked
buffer use <code>gnutls_record_check_corked()</code> .
</p>
<p><strong>Returns:</strong> On success the number of transmitted data is returned, or 
otherwise a negative error code. 
</p>
<p><strong>Since:</strong> 3.1.9
</p></dd></dl>


<hr>
<a name="Handling-alerts"></a>
<div class="header">
<p>
Next: <a href="#Priority-Strings" accesskey="n" rel="next">Priority Strings</a>, Previous: <a href="#Buffered-data-transfer" accesskey="p" rel="prev">Buffered data transfer</a>, Up: <a href="#How-to-use-GnuTLS-in-applications" accesskey="u" rel="up">How to use GnuTLS in applications</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Handling-alerts-1"></a>
<h3 class="section">6.9 Handling alerts</h3>
<p>During a TLS connection alert messages may be exchanged by the
two peers. Those messages may be fatal, meaning the connection
must be terminated afterwards, or warning when something needs
to be reported to the peer, but without interrupting the session.
The error codes <code>GNUTLS_E_WARNING_ALERT_RECEIVED</code>
or <code>GNUTLS_E_FATAL_ALERT_RECEIVED</code> signal those alerts
when received, and may be returned by all GnuTLS functions that receive 
data from the peer, being <a href="#gnutls_005fhandshake">gnutls_handshake</a> and <a href="#gnutls_005frecord_005frecv">gnutls_record_recv</a>.
</p>
<p>If those error codes are received the alert and its level should be logged
or reported to the peer using the functions below.
</p>



<dl>
<dt><a name="index-gnutls_005falert_005fget"></a>Function: <em>gnutls_alert_description_t</em> <strong>gnutls_alert_get</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function will return the last alert number received.  This
function should be called when <code>GNUTLS_E_WARNING_ALERT_RECEIVED</code>  or
<code>GNUTLS_E_FATAL_ALERT_RECEIVED</code>  errors are returned by a gnutls
function.  The peer may send alerts if he encounters an error.
If no alert has been received the returned value is undefined.
</p>
<p><strong>Returns:</strong> the last alert received, a
<code>gnutls_alert_description_t</code>  value.
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005falert_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_alert_get_name</strong> <em>(gnutls_alert_description_t <var>alert</var>)</em></dt>
<dd><p><var>alert</var>: is an alert number.
</p>
<p>This function will return a string that describes the given alert
number, or <code>NULL</code> .  See <code>gnutls_alert_get()</code> .
</p>
<p><strong>Returns:</strong> string corresponding to <code>gnutls_alert_description_t</code>  value.
</p></dd></dl>

<p>The peer may also be warned or notified of a fatal issue
by using one of the functions below. All the available alerts
are listed in <a href="#The-Alert-Protocol">The Alert Protocol</a>.
</p>




<dl>
<dt><a name="index-gnutls_005falert_005fsend"></a>Function: <em>int</em> <strong>gnutls_alert_send</strong> <em>(gnutls_session_t <var>session</var>, gnutls_alert_level_t <var>level</var>, gnutls_alert_description_t <var>desc</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>level</var>: is the level of the alert
</p>
<p><var>desc</var>: is the alert description
</p>
<p>This function will send an alert to the peer in order to inform
him of something important (eg. his Certificate could not be verified).
If the alert level is Fatal then the peer is expected to close the
connection, otherwise he may ignore the alert and continue.
</p>
<p>The error code of the underlying record send function will be
returned, so you may also receive <code>GNUTLS_E_INTERRUPTED</code>  or
<code>GNUTLS_E_AGAIN</code>  as well.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005ferror_005fto_005falert"></a>Function: <em>int</em> <strong>gnutls_error_to_alert</strong> <em>(int <var>err</var>, int * <var>level</var>)</em></dt>
<dd><p><var>err</var>: is a negative integer
</p>
<p><var>level</var>: the alert level will be stored there
</p>
<p>Get an alert depending on the error code returned by a gnutls
function.  All alerts sent by this function should be considered
fatal.  The only exception is when  <code>err</code> is <code>GNUTLS_E_REHANDSHAKE</code> ,
where a warning alert should be sent to the peer indicating that no
renegotiation will be performed.
</p>
<p>If there is no mapping to a valid alert the alert to indicate
internal error is returned.
</p>
<p><strong>Returns:</strong> the alert code to use for a particular error code.
</p></dd></dl>


<hr>
<a name="Priority-Strings"></a>
<div class="header">
<p>
Next: <a href="#Selecting-cryptographic-key-sizes" accesskey="n" rel="next">Selecting cryptographic key sizes</a>, Previous: <a href="#Handling-alerts" accesskey="p" rel="prev">Handling alerts</a>, Up: <a href="#How-to-use-GnuTLS-in-applications" accesskey="u" rel="up">How to use GnuTLS in applications</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Priority-strings"></a>
<h3 class="section">6.10 Priority strings</h3>
<a name="index-Priority-strings"></a>

<p>The GnuTLS priority strings specify the TLS session&rsquo;s handshake
algorithms and options in a compact, easy-to-use format.  That string
may contain a single initial keyword such as in
<a href="#tab_003aprio_002dkeywords">Table 6.3</a> and may be followed by additional algorithm or
special keywords. Note that their description is intentionally avoiding
specific algorithm details, as the priority strings are not constant between
gnutls versions (they are periodically updated to account for cryptographic
advances while providing compatibility with old clients and servers).
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpriority_005fset_005fdirect">gnutls_priority_set_direct</a> (gnutls_session_t <var>session</var>, const char * <var>priorities</var>, const char ** <var>err_pos</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpriority_005fset">gnutls_priority_set</a> (gnutls_session_t <var>session</var>, gnutls_priority_t <var>priority</var>)</code></dt>
</dl>

<div class="float"><a name="tab_003aprio_002dkeywords"></a>
<table>
<thead><tr><th width="20%">Keyword</th><th width="70%">Description</th></tr></thead>
<tr><td width="20%">@KEYWORD</td><td width="70%">Means that a compile-time specified system configuration file<a name="DOCF17" href="#FOOT17"><sup>17</sup></a> 
will be used to expand the provided keyword. That is used to impose system-specific policies.
It may be followed by additional options that will be appended to the
system string (e.g., &quot;@SYSTEM:+SRP&quot;). The system file should have the
format &rsquo;KEYWORD=VALUE&rsquo;, e.g., &rsquo;SYSTEM=NORMAL:+ARCFOUR-128&rsquo;.</td></tr>
<tr><td width="20%">PERFORMANCE</td><td width="70%">All the known to be secure ciphersuites are enabled,
limited to 128 bit ciphers and sorted by terms of speed
performance. The message authenticity security level is of 64 bits or more,
and the certificate verification profile is set to GNUTLS_PROFILE_LOW (80-bits).</td></tr>
<tr><td width="20%">NORMAL</td><td width="70%">Means all the known to be secure ciphersuites. The ciphers are sorted by security
margin, although the 256-bit ciphers are included as a fallback only.
The message authenticity security level is of 64 bits or more,
and the certificate verification profile is set to GNUTLS_PROFILE_LOW (80-bits).

<p>This priority string implicitly enables ECDHE and DHE. The ECDHE ciphersuites
are placed first in the priority order, but due to compatibility 
issues with the DHE ciphersuites they are placed last in the priority order,
after the plain RSA ciphersuites.
</p></td></tr>
<tr><td width="20%">LEGACY</td><td width="70%">This sets the NORMAL settings that were used for GnuTLS 3.2.x or earlier. There is
no verification profile set, and the allowed DH primes are considered
weak today (but are often used by misconfigured servers).</td></tr>
<tr><td width="20%">PFS</td><td width="70%">Means all the known to be secure ciphersuites that support perfect forward
secrecy (ECDHE and DHE). The ciphers are sorted by security
margin, although the 256-bit ciphers are included as a fallback only.
The message authenticity security level is of 80 bits or more,
and the certificate verification profile is set to GNUTLS_PROFILE_LOW (80-bits).
This option is available since 3.2.4 or later.</td></tr>
<tr><td width="20%">SECURE128</td><td width="70%">Means all known to be secure ciphersuites that offer a 
security level 128-bit or more.
The message authenticity security level is of 80 bits or more,
and the certificate verification profile is set to GNUTLS_PROFILE_LOW (80-bits).</td></tr>
<tr><td width="20%">SECURE192</td><td width="70%">Means all the known to be secure ciphersuites that offer a 
security level 192-bit or more.
The message authenticity security level is of 128 bits or more,
and the certificate verification profile is set to GNUTLS_PROFILE_HIGH (128-bits).</td></tr>
<tr><td width="20%">SECURE256</td><td width="70%">Currently alias for SECURE192. This option, will enable ciphers which use a
256-bit key but, due to limitations of the TLS protocol, the overall security
level will be 192-bits (the security level depends on more factors than cipher key size).</td></tr>
<tr><td width="20%">SUITEB128</td><td width="70%">Means all the NSA Suite B cryptography (RFC5430) ciphersuites
with an 128 bit security level, as well as the enabling of the corresponding
verification profile.</td></tr>
<tr><td width="20%">SUITEB192</td><td width="70%">Means all the NSA Suite B cryptography (RFC5430) ciphersuites
with an 192 bit security level, as well as the enabling of the corresponding
verification profile.</td></tr>
<tr><td width="20%">NONE</td><td width="70%">Means nothing is enabled.  This disables even protocols and
compression methods. It should be followed by the
algorithms to be enabled.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 6.3: </strong>Supported initial keywords.</p></div></div>
<p>Unless the initial keyword is &quot;NONE&quot; the defaults (in preference
order) are for TLS protocols TLS 1.2, TLS1.1, TLS1.0; for
compression NULL; for certificate types X.509.
In key exchange algorithms when in NORMAL or SECURE levels the
perfect forward secrecy algorithms take precedence of the other
protocols.  In all cases all the supported key exchange algorithms
are enabled.
</p>
<p>Note that the SECURE levels distinguish between overall security level and
message authenticity security level. That is because the message
authenticity security level requires the adversary to break
the algorithms at real-time during the protocol run, whilst 
the overall security level refers to off-line adversaries 
(e.g. adversaries breaking the ciphertext years after it was captured).
</p>
<p>The NONE keyword, if used, must followed by keywords specifying 
the algorithms and protocols to be enabled. The other initial keywords 
do not require, but may be followed by such keywords. All level keywords
can be combined, and for example a level of &quot;SECURE256:+SECURE128&quot; is
allowed.
</p>
<p>The order with which every algorithm or protocol
is specified is significant. Algorithms specified before others
will take precedence. The supported algorithms and protocols
are shown in <a href="#tab_003aprio_002dalgorithms">Table 6.4</a>. 
To avoid collisions in order to specify a compression algorithm in
the priority string you have to prefix it with &quot;COMP-&quot;, protocol versions
with &quot;VERS-&quot;, signature algorithms with &quot;SIGN-&quot; and certificate types with &quot;CTYPE-&quot;. 
All other algorithms don&rsquo;t need a prefix. Each specified keyword can
be prefixed with any of the following characters.
</p>
<dl compact="compact">
<dt>&rsquo;!&rsquo; or &rsquo;-&rsquo;</dt>
<dd><p>appended with an algorithm will remove this algorithm.
</p></dd>
<dt>&quot;+&quot;</dt>
<dd><p>appended with an algorithm will add this algorithm.
</p></dd>
</dl>

<div class="float"><a name="tab_003aprio_002dalgorithms"></a>
<table>
<thead><tr><th width="20%">Type</th><th width="70%">Keywords</th></tr></thead>
<tr><td width="20%">Ciphers</td><td width="70%">AES-128-CBC, AES-256-CBC, AES-128-GCM, CAMELLIA-128-CBC,
CAMELLIA-256-CBC, ARCFOUR-128, 3DES-CBC. Catch all
name is CIPHER-ALL which will add all the algorithms from NORMAL
priority.</td></tr>
<tr><td width="20%">Key exchange</td><td width="70%">RSA, DHE-RSA, DHE-DSS, SRP, SRP-RSA, SRP-DSS,
PSK, DHE-PSK, ECDHE-RSA, ANON-ECDH, ANON-DH. The
Catch all name is KX-ALL which will add all the algorithms from NORMAL
priority.

<p>Add <code>!DHE-RSA:!DHE-DSS</code> to the priority string to disable DHE.
</p></td></tr>
<tr><td width="20%">MAC</td><td width="70%">MD5, SHA1, SHA256, SHA384, AEAD (used with
GCM ciphers only). All algorithms from NORMAL priority can be accessed with MAC-ALL.</td></tr>
<tr><td width="20%">Compression algorithms</td><td width="70%">COMP-NULL, COMP-DEFLATE. Catch all is COMP-ALL.</td></tr>
<tr><td width="20%">TLS versions</td><td width="70%">VERS-TLS1.0, VERS-TLS1.1, VERS-TLS1.2,
VERS-DTLS1.0, VERS-DTLS1.2. 
Catch all are VERS-ALL, VERS-TLS-ALL and VERS-DTLS-ALL.</td></tr>
<tr><td width="20%">Signature algorithms</td><td width="70%">SIGN-RSA-SHA1, SIGN-RSA-SHA224, 
SIGN-RSA-SHA256, SIGN-RSA-SHA384, SIGN-RSA-SHA512, SIGN-DSA-SHA1, 
SIGN-DSA-SHA224, SIGN-DSA-SHA256, SIGN-RSA-MD5. Catch all
is SIGN-ALL. This is only valid for TLS 1.2 and later.</td></tr>
<tr><td width="20%">Elliptic curves</td><td width="70%">CURVE-SECP192R1, CURVE-SECP224R1, CURVE-SECP256R1, CURVE-SECP384R1, CURVE-SECP521R1. Catch all is CURVE-ALL.</td></tr>
<tr><td width="20%">Certificate type</td><td width="70%">CTYPE-OPENPGP, CTYPE-X509. Catch all is CTYPE-ALL.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 6.4: </strong>The supported algorithm keywords in priority strings.</p></div></div>
<p>Note that the DHE key exchange methods are generally
slower<a name="DOCF18" href="#FOOT18"><sup>18</sup></a> than their elliptic curves counterpart
(ECDHE). Moreover the plain Diffie-Hellman key exchange
requires parameters to be generated and associated with a credentials
structure by the server (see <a href="#Parameter-generation">Parameter generation</a>). 
</p>
<p>The available special keywords are shown in <a href="#tab_003aprio_002dspecial1">Table 6.5</a>
and <a href="#tab_003aprio_002dspecial2">Table 6.6</a>. 
</p>
<div class="float"><a name="tab_003aprio_002dspecial1"></a>
<table>
<thead><tr><th width="45%">Keyword</th><th width="45%">Description</th></tr></thead>
<tr><td width="45%">%COMPAT</td><td width="45%">will enable compatibility mode. It might mean that violations
of the protocols are allowed as long as maximum compatibility with
problematic clients and servers is achieved. More specifically this
string would disable TLS record random padding, tolerate packets
over the maximum allowed TLS record, and add a padding to TLS Client
Hello packet to prevent it being in the 256-512 range which is known
to be causing issues with a commonly used firewall.</td></tr>
<tr><td width="45%">%DUMBFW</td><td width="45%">will add a private extension with bogus data that make the client
hello exceed 512 bytes. This avoids a black hole behavior in some
firewalls. This is a non-standard TLS extension, use with care.</td></tr>
<tr><td width="45%">%NO_EXTENSIONS</td><td width="45%">will prevent the sending of any TLS extensions in client side. Note
that TLS 1.2 requires extensions to be used, as well as safe
renegotiation thus this option must be used with care.</td></tr>
<tr><td width="45%">%NO_TICKETS</td><td width="45%">will prevent the advertizing of the TLS session ticket extension.
This is implied by the PFS keyword.</td></tr>
<tr><td width="45%">%NO_SESSION_HASH</td><td width="45%">will prevent the advertizing the TLS extended master secret (session hash)
extension.</td></tr>
<tr><td width="45%">%SERVER_PRECEDENCE</td><td width="45%">The ciphersuite will be selected according to server priorities
and not the client&rsquo;s.</td></tr>
<tr><td width="45%">%SSL3_RECORD_VERSION</td><td width="45%">will use SSL3.0 record version in client hello.
This is the default.</td></tr>
<tr><td width="45%">%LATEST_RECORD_VERSION</td><td width="45%">will use the latest TLS version record version in client hello.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 6.5: </strong>Special priority string keywords.</p></div></div>
<div class="float"><a name="tab_003aprio_002dspecial2"></a>
<table>
<thead><tr><th width="45%">Keyword</th><th width="45%">Description</th></tr></thead>
<tr><td width="45%">%STATELESS_COMPRESSION</td><td width="45%">will disable keeping state across records when compressing. This may
help to mitigate attacks when compression is used but an attacker
is in control of input data. This has to be used only when the
data that are possibly controlled by an attacker are placed in
separate records.</td></tr>
<tr><td width="45%">%DISABLE_WILDCARDS</td><td width="45%">will disable matching wildcards when comparing hostnames
in certificates.</td></tr>
<tr><td width="45%">%NO_ETM</td><td width="45%">will disable the encrypt-then-mac TLS extension (RFC7366). This is
implied by the %COMPAT keyword.</td></tr>
<tr><td width="45%">%DISABLE_SAFE_RENEGOTIATION</td><td width="45%">will completely disable safe renegotiation
completely.  Do not use unless you know what you are doing.</td></tr>
<tr><td width="45%">%UNSAFE_RENEGOTIATION</td><td width="45%">will allow handshakes and re-handshakes
without the safe renegotiation extension.  Note that for clients
this mode is insecure (you may be under attack), and for servers it
will allow insecure clients to connect (which could be fooled by an
attacker).  Do not use unless you know what you are doing and want
maximum compatibility.</td></tr>
<tr><td width="45%">%PARTIAL_RENEGOTIATION</td><td width="45%">will allow initial handshakes to proceed,
but not re-handshakes.  This leaves the client vulnerable to attack,
and servers will be compatible with non-upgraded clients for
initial handshakes.  This is currently the default for clients and
servers, for compatibility reasons.</td></tr>
<tr><td width="45%">%SAFE_RENEGOTIATION</td><td width="45%">will enforce safe renegotiation.  Clients and
servers will refuse to talk to an insecure peer.  Currently this
causes interoperability problems, but is required for full protection.</td></tr>
<tr><td width="45%">%FALLBACK_SCSV</td><td width="45%">will enable the use of the fallback signaling cipher suite value in the
client hello.  Note that this should be set only by applications that
try to reconnect with a downgraded protocol version. See RFC7507 for
details.</td></tr>
<tr><td width="45%">%VERIFY_ALLOW_SIGN_RSA_MD5</td><td width="45%">will allow RSA-MD5 signatures in certificate chains.</td></tr>
<tr><td width="45%">%VERIFY_DISABLE_CRL_CHECKS</td><td width="45%">will disable CRL or OCSP checks in the verification of the certificate chain.</td></tr>
<tr><td width="45%">%VERIFY_ALLOW_X509_V1_CA_CRT</td><td width="45%">will allow V1 CAs in chains.</td></tr>
<tr><td width="45%">%PROFILE_(LOW|LEGACY|MEDIUM|HIGH|ULTRA)</td><td width="45%">require a certificate verification profile the corresponds to the specified
security level, see <a href="#tab_003akey_002dsizes">Table 6.7</a> for the mappings to values.</td></tr>
<tr><td width="45%">%PROFILE_(SUITEB128|SUITEB192)</td><td width="45%">require a certificate verification profile the corresponds to SUITEB. Note
that an initial keyword that enables SUITEB automatically sets the profile.</td></tr>
</table>

<div class="float-caption"><p><strong>Table 6.6: </strong>More priority string keywords.</p></div></div>
<p>Finally the ciphersuites enabled by any priority string can be
listed using the <code>gnutls-cli</code> application (see <a href="#gnutls_002dcli-Invocation">gnutls-cli Invocation</a>), 
or by using the priority functions as in <a href="#Listing-the-ciphersuites-in-a-priority-string">Listing the ciphersuites in a priority string</a>.
</p>
<p>Example priority strings are:
</p><div class="example">
<pre class="example">The system imposed security level:
    &quot;SYSTEM&quot;

The default priority without the HMAC-MD5:
    &quot;NORMAL:-MD5&quot;

Specifying RSA with AES-128-CBC:
    &quot;NONE:+VERS-TLS-ALL:+MAC-ALL:+RSA:+AES-128-CBC:+SIGN-ALL:+COMP-NULL&quot;

Specifying the defaults plus ARCFOUR-128:
    &quot;NORMAL:+ARCFOUR-128&quot;

Enabling the 128-bit secure ciphers, while disabling TLS 1.0 and enabling compression:
    &quot;SECURE128:-VERS-TLS1.0:+COMP-DEFLATE&quot;

Enabling the 128-bit and 192-bit secure ciphers, while disabling all TLS versions 
except TLS 1.2:
    &quot;SECURE128:+SECURE192:-VERS-TLS-ALL:+VERS-TLS1.2&quot;
</pre></div>

<hr>
<a name="Selecting-cryptographic-key-sizes"></a>
<div class="header">
<p>
Next: <a href="#Advanced-topics" accesskey="n" rel="next">Advanced topics</a>, Previous: <a href="#Priority-Strings" accesskey="p" rel="prev">Priority Strings</a>, Up: <a href="#How-to-use-GnuTLS-in-applications" accesskey="u" rel="up">How to use GnuTLS in applications</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Selecting-cryptographic-key-sizes-1"></a>
<h3 class="section">6.11 Selecting cryptographic key sizes</h3>
<a name="index-key-sizes"></a>

<p>Because many algorithms are involved in TLS, it is not easy to set
a consistent security level.  For this reason in <a href="#tab_003akey_002dsizes">Table 6.7</a> we
present some correspondence between key sizes of symmetric algorithms
and public key algorithms based on [<em>ECRYPT</em>]. 
Those can be used to generate certificates with
appropriate key sizes as well as select parameters for Diffie-Hellman and SRP
authentication.
</p>
<div class="float"><a name="tab_003akey_002dsizes"></a>
<table>
<thead><tr><th width="10%">Security bits</th><th width="12%">RSA, DH and SRP parameter size</th><th width="10%">ECC key size</th><th width="20%">Security parameter (profile)</th><th width="32%">Description</th></tr></thead>
<tr><td width="10%">&lt;64</td><td width="12%">&lt;768</td><td width="10%">&lt;128</td><td width="20%"><code>INSECURE</code></td><td width="32%">Considered to be insecure</td></tr>
<tr><td width="10%">64</td><td width="12%">768</td><td width="10%">128</td><td width="20%"><code>VERY WEAK</code></td><td width="32%">Short term protection against individuals</td></tr>
<tr><td width="10%">72</td><td width="12%">1008</td><td width="10%">160</td><td width="20%"><code>WEAK</code></td><td width="32%">Short term protection against small organizations</td></tr>
<tr><td width="10%">80</td><td width="12%">1024</td><td width="10%">160</td><td width="20%"><code>LOW</code></td><td width="32%">Very short term protection against agencies (corresponds to ENISA legacy level)</td></tr>
<tr><td width="10%">96</td><td width="12%">1776</td><td width="10%">192</td><td width="20%"><code>LEGACY</code></td><td width="32%">Legacy standard level</td></tr>
<tr><td width="10%">112</td><td width="12%">2048</td><td width="10%">224</td><td width="20%"><code>MEDIUM</code></td><td width="32%">Medium-term protection</td></tr>
<tr><td width="10%">128</td><td width="12%">3072</td><td width="10%">256</td><td width="20%"><code>HIGH</code></td><td width="32%">Long term protection (corresponds to ENISA future level)</td></tr>
<tr><td width="10%">192</td><td width="12%">8192</td><td width="10%">384</td><td width="20%"><code>ULTRA</code></td><td width="32%">Even longer term protection</td></tr>
<tr><td width="10%">256</td><td width="12%">15424</td><td width="10%">512</td><td width="20%"><code>FUTURE</code></td><td width="32%">Foreseeable future</td></tr>
</table>

<div class="float-caption"><p><strong>Table 6.7: </strong>Key sizes and security parameters.</p></div></div>
<p>The first column  provides a security parameter in a number of bits. This
gives an indication of the number of combinations to be tried by an adversary
to brute force a key. For example to test all possible keys in a 112 bit security parameter
<em>2^{112}</em> combinations have to be tried. For today&rsquo;s technology this is infeasible.
The next two columns correlate the security
parameter with actual bit sizes of parameters for DH, RSA, SRP and ECC algorithms.
A mapping to <code>gnutls_sec_param_t</code> value is given for each security parameter, on
the next column, and finally a brief description of the level.
</p>

<p>Note, however, that the values suggested here are nothing more than an
educated guess that is valid today. There are no guarantees that an
algorithm will remain unbreakable or that these values will remain
constant in time. There could be scientific breakthroughs that cannot
be predicted or total failure of the current public key systems by
quantum computers. On the other hand though the cryptosystems used in
TLS are selected in a conservative way and such catastrophic
breakthroughs or failures are believed to be unlikely.
The NIST publication SP 800-57 [<em>NISTSP80057</em>] contains a similar
table.
</p>
<p>When using <acronym>GnuTLS</acronym> and a decision on bit sizes for a public
key algorithm is required, use of the following functions is  
recommended:
</p>




<dl>
<dt><a name="index-gnutls_005fsec_005fparam_005fto_005fpk_005fbits"></a>Function: <em>unsigned int</em> <strong>gnutls_sec_param_to_pk_bits</strong> <em>(gnutls_pk_algorithm_t <var>algo</var>, gnutls_sec_param_t <var>param</var>)</em></dt>
<dd><p><var>algo</var>: is a public key algorithm
</p>
<p><var>param</var>: is a security parameter
</p>
<p>When generating private and public key pairs a difficult question
is which size of &quot;bits&quot; the modulus will be in RSA and the group size
in DSA. The easy answer is 1024, which is also wrong. This function
will convert a human understandable security parameter to an
appropriate size for the specific algorithm.
</p>
<p><strong>Returns:</strong> The number of bits, or (0).
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>





<dl>
<dt><a name="index-gnutls_005fpk_005fbits_005fto_005fsec_005fparam"></a>Function: <em>gnutls_sec_param_t</em> <strong>gnutls_pk_bits_to_sec_param</strong> <em>(gnutls_pk_algorithm_t <var>algo</var>, unsigned int <var>bits</var>)</em></dt>
<dd><p><var>algo</var>: is a public key algorithm
</p>
<p><var>bits</var>: is the number of bits
</p>
<p>This is the inverse of <code>gnutls_sec_param_to_pk_bits()</code> . Given an algorithm
and the number of bits, it will return the security parameter. This is
a rough indication.
</p>
<p><strong>Returns:</strong> The security parameter.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<p>Those functions will convert a human understandable security parameter
of <code>gnutls_sec_param_t</code> type, to a number of bits suitable for a public 
key algorithm.
</p>
<dl compact="compact">
<dt><code><var>const char *</var> <a href="#gnutls_005fsec_005fparam_005fget_005fname">gnutls_sec_param_get_name</a> (gnutls_sec_param_t <var>param</var>)</code></dt>
</dl>

<p>The following functions will set the minimum acceptable group size for Diffie-Hellman
and SRP authentication. 
</p><dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005fdh_005fset_005fprime_005fbits">gnutls_dh_set_prime_bits</a> (gnutls_session_t <var>session</var>, unsigned int <var>bits</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fsrp_005fset_005fprime_005fbits">gnutls_srp_set_prime_bits</a> (gnutls_session_t <var>session</var>, unsigned int <var>bits</var>)</code></dt>
</dl>


<hr>
<a name="Advanced-topics"></a>
<div class="header">
<p>
Previous: <a href="#Selecting-cryptographic-key-sizes" accesskey="p" rel="prev">Selecting cryptographic key sizes</a>, Up: <a href="#How-to-use-GnuTLS-in-applications" accesskey="u" rel="up">How to use GnuTLS in applications</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Advanced-topics-1"></a>
<h3 class="section">6.12 Advanced topics</h3>

<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Session-resumption" accesskey="1">Session resumption</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Certificate-verification" accesskey="2">Certificate verification</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Re_002dauthentication" accesskey="3">Re-authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Parameter-generation" accesskey="4">Parameter generation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Deriving-keys-for-other-applications_002fprotocols" accesskey="5">Deriving keys for other applications/protocols</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Channel-Bindings" accesskey="6">Channel Bindings</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Interoperability" accesskey="7">Interoperability</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Compatibility-with-the-OpenSSL-library" accesskey="8">Compatibility with the OpenSSL library</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Session-resumption"></a>
<div class="header">
<p>
Next: <a href="#Certificate-verification" accesskey="n" rel="next">Certificate verification</a>, Up: <a href="#Advanced-topics" accesskey="u" rel="up">Advanced topics</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Session-resumption-1"></a>
<h4 class="subsection">6.12.1 Session resumption</h4>
<a name="index-resuming-sessions-1"></a>
<a name="index-session-resumption-1"></a>

<a name="Client-side-1"></a>
<h4 class="subsubheading">Client side</h4>

<p>To reduce time and roundtrips spent in a handshake the client can   
request session resumption from a server that previously shared
a session with the client. For that the client has to retrieve and store
the session parameters. Before establishing a new session to the same 
server the parameters must be re-associated with the GnuTLS session
using <a href="#gnutls_005fsession_005fset_005fdata">gnutls_session_set_data</a>.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fsession_005fget_005fdata2">gnutls_session_get_data2</a> (gnutls_session_t <var>session</var>, gnutls_datum_t * <var>data</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fsession_005fget_005fid2">gnutls_session_get_id2</a> (gnutls_session_t <var>session</var>, gnutls_datum_t * <var>session_id</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fsession_005fset_005fdata">gnutls_session_set_data</a> (gnutls_session_t <var>session</var>, const void * <var>session_data</var>, size_t <var>session_data_size</var>)</code></dt>
</dl>

<p>Keep in mind that sessions will be expired after some time, depending
on the server, and a server may choose not to resume a session
even when requested to.  The expiration is to prevent temporal session keys
from becoming long-term keys. Also note that as a client you must enable, 
using the priority functions, at least the algorithms used in the last session.
</p>




<dl>
<dt><a name="index-gnutls_005fsession_005fis_005fresumed"></a>Function: <em>int</em> <strong>gnutls_session_is_resumed</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Check whether session is resumed or not.
</p>
<p><strong>Returns:</strong> non zero if this session is resumed, or a zero if this is
a new session.
</p></dd></dl>

<a name="Server-side-1"></a>
<h4 class="subsubheading">Server side</h4>

<p>In order to support resumption a server can store
the session security parameters in a local database or by using session
tickets (see <a href="#Session-tickets">Session tickets</a>) to delegate storage to the client. Because
session tickets might not be supported by all clients, servers
could combine the two methods.
</p>
<p>A storing server needs to specify callback functions to store, retrieve and delete session data. These can be
registered with the functions below. The stored sessions in the database can be checked using <a href="#gnutls_005fdb_005fcheck_005fentry">gnutls_db_check_entry</a>
for expiration.
</p>
<dl compact="compact">
<dt><code><var>void</var> <a href="#gnutls_005fdb_005fset_005fretrieve_005ffunction">gnutls_db_set_retrieve_function</a> (gnutls_session_t <var>session</var>, gnutls_db_retr_func <var>retr_func</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fdb_005fset_005fstore_005ffunction">gnutls_db_set_store_function</a> (gnutls_session_t <var>session</var>, gnutls_db_store_func <var>store_func</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fdb_005fset_005fptr">gnutls_db_set_ptr</a> (gnutls_session_t <var>session</var>, void * <var>ptr</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fdb_005fset_005fremove_005ffunction">gnutls_db_set_remove_function</a> (gnutls_session_t <var>session</var>, gnutls_db_remove_func <var>rem_func</var>)</code></dt>
</dl>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fdb_005fcheck_005fentry">gnutls_db_check_entry</a> (gnutls_session_t <var>session</var>, gnutls_datum_t <var>session_entry</var>)</code></dt>
</dl>

<p>A server utilizing tickets should generate ticket encryption
and authentication keys using <a href="#gnutls_005fsession_005fticket_005fkey_005fgenerate">gnutls_session_ticket_key_generate</a>.
Those keys should be associated with the GnuTLS session using
<a href="#gnutls_005fsession_005fticket_005fenable_005fserver">gnutls_session_ticket_enable_server</a>, and should be rotated regularly
(e.g., every few hours), to prevent them from becoming long-term keys which
if revealed could be used to decrypt all previous sessions.
</p>




<dl>
<dt><a name="index-gnutls_005fsession_005fticket_005fenable_005fserver"></a>Function: <em>int</em> <strong>gnutls_session_ticket_enable_server</strong> <em>(gnutls_session_t <var>session</var>, const gnutls_datum_t * <var>key</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>key</var>: key to encrypt session parameters.
</p>
<p>Request that the server should attempt session resumption using
SessionTicket.   <code>key</code> must be initialized with
<code>gnutls_session_ticket_key_generate()</code> , and should be overwritten
using <code>gnutls_memset()</code>  before being released.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fsession_005fticket_005fkey_005fgenerate"></a>Function: <em>int</em> <strong>gnutls_session_ticket_key_generate</strong> <em>(gnutls_datum_t * <var>key</var>)</em></dt>
<dd><p><var>key</var>: is a pointer to a <code>gnutls_datum_t</code>  which will contain a newly
created key.
</p>
<p>Generate a random key to encrypt security parameters within
SessionTicket.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fsession_005fresumption_005frequested"></a>Function: <em>int</em> <strong>gnutls_session_resumption_requested</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Check whether the client has asked for session resumption.
This function is valid only on server side.
</p>
<p><strong>Returns:</strong> non zero if session resumption was asked, or a zero if not.
</p></dd></dl>

<p>A server enabling both session tickets and a storage for session data
would use session tickets when clients support it and the storage otherwise.
</p>
<hr>
<a name="Certificate-verification"></a>
<div class="header">
<p>
Next: <a href="#Re_002dauthentication" accesskey="n" rel="next">Re-authentication</a>, Previous: <a href="#Session-resumption" accesskey="p" rel="prev">Session resumption</a>, Up: <a href="#Advanced-topics" accesskey="u" rel="up">Advanced topics</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Certificate-verification-1"></a>
<h4 class="subsection">6.12.2 Certificate verification</h4>
<a name="index-DANE-1"></a>
<a name="index-DNSSEC-1"></a>
<a name="index-SSH_002dstyle-authentication-1"></a>
<a name="index-Trust-on-first-use-1"></a>
<a name="index-Key-pinning-1"></a>
<a name="index-gnutls_005fcertificate_005fverify_005fflags-1"></a>

<p>In this section the functionality for additional certificate verification methods is listed. 
These methods are intended to be used in addition to normal PKI verification, in order to reduce 
the risk of a compromised CA being undetected.
</p>
<a name="Trust-on-first-use"></a>
<h4 class="subsubsection">6.12.2.1 Trust on first use</h4>

<p>The GnuTLS library includes functionlity to use an SSH-like trust on first use authentication.
The available functions to store and verify public keys are listed below.
</p>




<dl>
<dt><a name="index-gnutls_005fverify_005fstored_005fpubkey"></a>Function: <em>int</em> <strong>gnutls_verify_stored_pubkey</strong> <em>(const char * <var>db_name</var>, gnutls_tdb_t <var>tdb</var>, const char * <var>host</var>, const char * <var>service</var>, gnutls_certificate_type_t <var>cert_type</var>, const gnutls_datum_t * <var>cert</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>db_name</var>: A file specifying the stored keys (use NULL for the default)
</p>
<p><var>tdb</var>: A storage structure or NULL to use the default
</p>
<p><var>host</var>: The peer&rsquo;s name
</p>
<p><var>service</var>: non-NULL if this key is specific to a service (e.g. http)
</p>
<p><var>cert_type</var>: The type of the certificate
</p>
<p><var>cert</var>: The raw (der) data of the certificate
</p>
<p><var>flags</var>: should be 0.
</p>
<p>This function will try to verify the provided (raw or DER-encoded) certificate 
using a list of stored public keys.  The  <code>service</code> field if non-NULL should
be a port number.
</p>
<p>The  <code>retrieve</code> variable if non-null specifies a custom backend for
the retrieval of entries. If it is NULL then the
default file backend will be used. In POSIX-like systems the
file backend uses the $HOME/.gnutls/known_hosts file.
</p>
<p>Note that if the custom storage backend is provided the
retrieval function should return <code>GNUTLS_E_CERTIFICATE_KEY_MISMATCH</code> 
if the host/service pair is found but key doesn&rsquo;t match,
<code>GNUTLS_E_NO_CERTIFICATE_FOUND</code>  if no such host/service with
the given key is found, and 0 if it was found. The storage
function should return 0 on success.
</p>
<p><strong>Returns:</strong> If no associated public key is found
then <code>GNUTLS_E_NO_CERTIFICATE_FOUND</code>  will be returned. If a key
is found but does not match <code>GNUTLS_E_CERTIFICATE_KEY_MISMATCH</code> 
is returned. On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, 
or a negative error value on other errors.
</p>
<p><strong>Since:</strong> 3.0.13
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fstore_005fpubkey"></a>Function: <em>int</em> <strong>gnutls_store_pubkey</strong> <em>(const char * <var>db_name</var>, gnutls_tdb_t <var>tdb</var>, const char * <var>host</var>, const char * <var>service</var>, gnutls_certificate_type_t <var>cert_type</var>, const gnutls_datum_t * <var>cert</var>, time_t <var>expiration</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>db_name</var>: A file specifying the stored keys (use NULL for the default)
</p>
<p><var>tdb</var>: A storage structure or NULL to use the default
</p>
<p><var>host</var>: The peer&rsquo;s name
</p>
<p><var>service</var>: non-NULL if this key is specific to a service (e.g. http)
</p>
<p><var>cert_type</var>: The type of the certificate
</p>
<p><var>cert</var>: The data of the certificate
</p>
<p><var>expiration</var>: The expiration time (use 0 to disable expiration)
</p>
<p><var>flags</var>: should be 0.
</p>
<p>This function will store the provided (raw or DER-encoded) certificate to 
the list of stored public keys. The key will be considered valid until 
the provided expiration time.
</p>
<p>The  <code>store</code> variable if non-null specifies a custom backend for
the storage of entries. If it is NULL then the
default file backend will be used.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0.13
</p></dd></dl>

<p>In addition to the above the <a href="#gnutls_005fstore_005fcommitment">gnutls_store_commitment</a> can be 
used to implement a key-pinning architecture as in [<em>KEYPIN</em>]. 
This provides a way for web server to commit on a public key that is
not yet active.
</p>




<dl>
<dt><a name="index-gnutls_005fstore_005fcommitment"></a>Function: <em>int</em> <strong>gnutls_store_commitment</strong> <em>(const char * <var>db_name</var>, gnutls_tdb_t <var>tdb</var>, const char * <var>host</var>, const char * <var>service</var>, gnutls_digest_algorithm_t <var>hash_algo</var>, const gnutls_datum_t * <var>hash</var>, time_t <var>expiration</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>db_name</var>: A file specifying the stored keys (use NULL for the default)
</p>
<p><var>tdb</var>: A storage structure or NULL to use the default
</p>
<p><var>host</var>: The peer&rsquo;s name
</p>
<p><var>service</var>: non-NULL if this key is specific to a service (e.g. http)
</p>
<p><var>hash_algo</var>: The hash algorithm type
</p>
<p><var>hash</var>: The raw hash
</p>
<p><var>expiration</var>: The expiration time (use 0 to disable expiration)
</p>
<p><var>flags</var>: should be 0.
</p>
<p>This function will store the provided hash commitment to 
the list of stored public keys. The key with the given
hash will be considered valid until the provided expiration time.
</p>
<p>The  <code>store</code> variable if non-null specifies a custom backend for
the storage of entries. If it is NULL then the
default file backend will be used.
</p>
<p>Note that this function is not thread safe with the default backend.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<p>The storage and verification functions may be used with the default
text file based back-end, or another back-end may be specified. That
should contain storage and retrieval functions and specified as below.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005ftdb_005finit">gnutls_tdb_init</a> (gnutls_tdb_t * <var>tdb</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005ftdb_005fdeinit">gnutls_tdb_deinit</a> (gnutls_tdb_t <var>tdb</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005ftdb_005fset_005fverify_005ffunc">gnutls_tdb_set_verify_func</a> (gnutls_tdb_t <var>tdb</var>, gnutls_tdb_verify_func <var>verify</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005ftdb_005fset_005fstore_005ffunc">gnutls_tdb_set_store_func</a> (gnutls_tdb_t <var>tdb</var>, gnutls_tdb_store_func <var>store</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005ftdb_005fset_005fstore_005fcommitment_005ffunc">gnutls_tdb_set_store_commitment_func</a> (gnutls_tdb_t <var>tdb</var>, gnutls_tdb_store_commitment_func        <var>cstore</var>)</code></dt>
</dl>

<a name="DANE-verification"></a>
<h4 class="subsubsection">6.12.2.2 DANE verification</h4>
<p>Since the DANE library is not included in GnuTLS it requires programs
to be linked against it. This can be achieved with the following commands.
</p>
<div class="example">
<pre class="example">gcc -o foo foo.c `pkg-config gnutls-dane --cflags --libs`
</pre></div>

<p>When a program uses the GNU autoconf system, then the following
line or similar can be used to detect the presence of the library.
</p>
<div class="example">
<pre class="example">PKG_CHECK_MODULES([LIBDANE], [gnutls-dane &gt;= 3.0.0])

AC_SUBST([LIBDANE_CFLAGS])
AC_SUBST([LIBDANE_LIBS])
</pre></div>

<p>The high level functionality provided by the DANE library is shown below.
</p>




<dl>
<dt><a name="index-dane_005fverify_005fcrt"></a>Function: <em>int</em> <strong>dane_verify_crt</strong> <em>(dane_state_t <var>s</var>, const gnutls_datum_t * <var>chain</var>, unsigned <var>chain_size</var>, gnutls_certificate_type_t <var>chain_type</var>, const char * <var>hostname</var>, const char * <var>proto</var>, unsigned int <var>port</var>, unsigned int <var>sflags</var>, unsigned int <var>vflags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>s</var>: A DANE state structure (may be NULL)
</p>
<p><var>chain</var>: A certificate chain
</p>
<p><var>chain_size</var>: The size of the chain
</p>
<p><var>chain_type</var>: The type of the certificate chain
</p>
<p><var>hostname</var>: The hostname associated with the chain
</p>
<p><var>proto</var>: The protocol of the service connecting (e.g. tcp)
</p>
<p><var>port</var>: The port of the service connecting (e.g. 443)
</p>
<p><var>sflags</var>: Flags for the the initialization of  <code>s</code> (if NULL)
</p>
<p><var>vflags</var>: Verification flags; an OR&rsquo;ed list of <code>dane_verify_flags_t</code> .
</p>
<p><var>verify</var>: An OR&rsquo;ed list of <code>dane_verify_status_t</code> .
</p>
<p>This function will verify the given certificate chain against the
CA constrains and/or the certificate available via DANE.
If no information via DANE can be obtained the flag <code>DANE_VERIFY_NO_DANE_INFO</code> 
is set. If a DNSSEC signature is not available for the DANE
record then the verify flag <code>DANE_VERIFY_NO_DNSSEC_DATA</code>  is set.
</p>
<p>Due to the many possible options of DANE, there is no single threat
model countered. When notifying the user about DANE verification results
it may be better to mention: DANE verification did not reject the certificate,
rather than mentioning a successful DANE verication.
</p>
<p>Note that this function is designed to be run in addition to
PKIX - certificate chain - verification. To be run independently
the <code>DANE_VFLAG_ONLY_CHECK_EE_USAGE</code>  flag should be specified; 
then the function will check whether the key of the peer matches the
key advertized in the DANE entry.
</p>
<p>If the  <code>q</code> parameter is provided it will be used for caching entries.
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<dl compact="compact">
<dt><code><var>int</var> <a href="#dane_005fverify_005fsession_005fcrt">dane_verify_session_crt</a> (dane_state_t <var>s</var>, gnutls_session_t <var>session</var>, const char * <var>hostname</var>, const char * <var>proto</var>, unsigned int <var>port</var>, unsigned int <var>sflags</var>, unsigned int <var>vflags</var>, unsigned int * <var>verify</var>)</code></dt>
<dt><code><var>const char *</var> <a href="#dane_005fstrerror">dane_strerror</a> (int <var>error</var>)</code></dt>
</dl>

<p>Note that the <code>dane_state_t</code> structure that is accepted by both
verification functions is optional. It is required when many queries
are performed to facilitate caching.
The following flags are returned by the verify functions to
indicate the status of the verification.
</p>
<div class="float"><a name="dane_005fverify_005fstatus_005ft"></a>


<dl compact="compact">
<dt><code>DANE_VERIFY_CA_CONSTRAINTS_VIOLATED</code></dt>
<dd><p>The CA constraints were violated.
</p></dd>
<dt><code>DANE_VERIFY_CERT_DIFFERS</code></dt>
<dd><p>The certificate obtained via DNS differs.
</p></dd>
<dt><code>DANE_VERIFY_UNKNOWN_DANE_INFO</code></dt>
<dd><p>No known DANE data was found in the DNS record.
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 6.2: </strong>The DANE verification status flags.</p></div></div>
<p>In order to generate a DANE TLSA entry to use in a DNS server 
you may use danetool (see <a href="#danetool-Invocation">danetool Invocation</a>).
</p>


<hr>
<a name="Re_002dauthentication"></a>
<div class="header">
<p>
Next: <a href="#Parameter-generation" accesskey="n" rel="next">Parameter generation</a>, Previous: <a href="#Certificate-verification" accesskey="p" rel="prev">Certificate verification</a>, Up: <a href="#Advanced-topics" accesskey="u" rel="up">Advanced topics</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Re_002dauthentication-1"></a>
<h4 class="subsection">6.12.3 Re-authentication</h4>
<a name="index-renegotiation-1"></a>
<a name="index-reauthentication"></a>

<p>In TLS there is no distinction between rekey, re-authentication, and re-negotiation.
All of these use cases are handled by the TLS&rsquo; rehandshake process. For that reason
in GnuTLS rehandshake is not transparent to the application, and the application
must take control of that process. The following paragraphs explain how to safely
use the rehandshake process.
</p>
<a name="Client-side"></a>
<h4 class="subsubsection">6.12.3.1 Client side</h4>

<p>According to the TLS specification a client may initiate a rehandshake at any
time. That can be achieved by calling <a href="#gnutls_005fhandshake">gnutls_handshake</a> and rely on its
return value for the outcome of the handshake (the server may deny a rehandshake).
If a server requests a re-handshake, then a call to <a href="#gnutls_005frecord_005frecv">gnutls_record_recv</a> will
return GNUTLS_E_REHANDSHAKE in the client, instructing it to call <a href="#gnutls_005fhandshake">gnutls_handshake</a>.
To deny a rehandshake request by the server it is recommended to send a warning alert
of type GNUTLS_A_NO_RENEGOTIATION.
</p>
<p>Due to limitations of early protocol versions, it is required to check whether
safe renegotiation is in place, i.e., using <a href="#gnutls_005fsafe_005frenegotiation_005fstatus">gnutls_safe_renegotiation_status</a>,
which ensures that the server remains the same as the initial. For older servers,
which do not support renegotiation, it is required on the second handshake
to verify that their certificate/credentials remained the same as in the initial
session.
</p>




<dl>
<dt><a name="index-gnutls_005fsafe_005frenegotiation_005fstatus"></a>Function: <em>int</em> <strong>gnutls_safe_renegotiation_status</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Can be used to check whether safe renegotiation is being used
in the current session.
</p>
<p><strong>Returns:</strong> 0 when safe renegotiation is not used and non (0) when
safe renegotiation is used.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="Server-side"></a>
<h4 class="subsubsection">6.12.3.2 Server side</h4>

<p>A server which wants to instruct the client to re-authenticate, should call
<a href="#gnutls_005frehandshake">gnutls_rehandshake</a> and wait for the client to re-authenticate.
It is recommended to only request re-handshake when safe renegotiation is
enabled for that session (see <a href="#gnutls_005fsafe_005frenegotiation_005fstatus">gnutls_safe_renegotiation_status</a> and
the discussion in <a href="#Safe-renegotiation">Safe renegotiation</a>).
</p>




<dl>
<dt><a name="index-gnutls_005frehandshake"></a>Function: <em>int</em> <strong>gnutls_rehandshake</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function will renegotiate security parameters with the
client.  This should only be called in case of a server.
</p>
<p>This message informs the peer that we want to renegotiate
parameters (perform a handshake).
</p>
<p>If this function succeeds (returns 0), you must call the
<code>gnutls_handshake()</code>  function in order to negotiate the new
parameters.
</p>
<p>Since TLS is full duplex some application data might have been
sent during peer&rsquo;s processing of this message. In that case
one should call <code>gnutls_record_recv()</code>  until GNUTLS_E_REHANDSHAKE
is returned to clear any pending data. Care must be taken, if
rehandshake is mandatory, to terminate if it does not start after
some threshold.
</p>
<p>If the client does not wish to renegotiate parameters he 
should reply with an alert message, thus the return code will be
<code>GNUTLS_E_WARNING_ALERT_RECEIVED</code>  and the alert will be
<code>GNUTLS_A_NO_RENEGOTIATION</code> .  A client may also choose to ignore
this message.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p></dd></dl>

<hr>
<a name="Parameter-generation"></a>
<div class="header">
<p>
Next: <a href="#Deriving-keys-for-other-applications_002fprotocols" accesskey="n" rel="next">Deriving keys for other applications/protocols</a>, Previous: <a href="#Re_002dauthentication" accesskey="p" rel="prev">Re-authentication</a>, Up: <a href="#Advanced-topics" accesskey="u" rel="up">Advanced topics</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Parameter-generation-1"></a>
<h4 class="subsection">6.12.4 Parameter generation</h4>
<a name="index-parameter-generation"></a>
<a name="index-generating-parameters"></a>

<p>Several TLS ciphersuites require additional parameters that
need to be generated or provided by the application. The
Diffie-Hellman based ciphersuites (ANON-DH or DHE), require
the group parameters to be provided. Those can either be
be generated on the fly using <a href="#gnutls_005fdh_005fparams_005fgenerate2">gnutls_dh_params_generate2</a>
or imported from pregenerated data using <a href="#gnutls_005fdh_005fparams_005fimport_005fpkcs3">gnutls_dh_params_import_pkcs3</a>.
The parameters can be used in a <acronym>TLS</acronym> session by calling
<a href="#gnutls_005fcertificate_005fset_005fdh_005fparams">gnutls_certificate_set_dh_params</a> or
<a href="#gnutls_005fanon_005fset_005fserver_005fdh_005fparams">gnutls_anon_set_server_dh_params</a> for anonymous sessions.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fdh_005fparams_005fgenerate2">gnutls_dh_params_generate2</a> (gnutls_dh_params_t <var>dparams</var>, unsigned int <var>bits</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fdh_005fparams_005fimport_005fpkcs3">gnutls_dh_params_import_pkcs3</a> (gnutls_dh_params_t <var>params</var>, const gnutls_datum_t * <var>pkcs3_params</var>, gnutls_x509_crt_fmt_t <var>format</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fcertificate_005fset_005fdh_005fparams">gnutls_certificate_set_dh_params</a> (gnutls_certificate_credentials_t <var>res</var>, gnutls_dh_params_t <var>dh_params</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fanon_005fset_005fserver_005fdh_005fparams">gnutls_anon_set_server_dh_params</a> (gnutls_anon_server_credentials_t <var>res</var>, gnutls_dh_params_t <var>dh_params</var>)</code></dt>
</dl>

<p>Due to the time-consuming calculations required for the generation
of Diffie-Hellman parameters we suggest against performing generation
of them within an application. The <code>certtool</code> tool can be used to 
generate or export known safe values that can be stored in code
or in a configuration file to provide the ability to replace. We also
recommend the usage of <a href="#gnutls_005fsec_005fparam_005fto_005fpk_005fbits">gnutls_sec_param_to_pk_bits</a> 
(see <a href="#Selecting-cryptographic-key-sizes">Selecting cryptographic key sizes</a>) to determine
the bit size of the generated parameters.
</p>
<p>Note that the information stored in the generated PKCS #3 structure
changed with GnuTLS 3.0.9. Since that version the <code>privateValueLength</code>
member of the structure is set, allowing the server utilizing the
parameters to use keys of the size of the security parameter. This
provides better performance in key exchange.
</p>
<p>To allow renewal of the parameters within an application without
accessing the credentials, which are a shared structure,
an alternative interface is available using a callback function.  
</p>




<dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fparams_005ffunction"></a>Function: <em>void</em> <strong>gnutls_certificate_set_params_function</strong> <em>(gnutls_certificate_credentials_t            <var>res</var>, gnutls_params_function * <var>func</var>)</em></dt>
<dd><p><var>res</var>: is a gnutls_certificate_credentials_t type
</p>
<p><var>func</var>: is the function to be called
</p>
<p>This function will set a callback in order for the server to get
the Diffie-Hellman or RSA parameters for certificate
authentication.  The callback should return <code>GNUTLS_E_SUCCESS</code>  (0) on success.
</p></dd></dl>


<hr>
<a name="Deriving-keys-for-other-applications_002fprotocols"></a>
<div class="header">
<p>
Next: <a href="#Channel-Bindings" accesskey="n" rel="next">Channel Bindings</a>, Previous: <a href="#Parameter-generation" accesskey="p" rel="prev">Parameter generation</a>, Up: <a href="#Advanced-topics" accesskey="u" rel="up">Advanced topics</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Deriving-keys-for-other-applications_002fprotocols-1"></a>
<h4 class="subsection">6.12.5 Deriving keys for other applications/protocols</h4>
<a name="index-keying-material-exporters"></a>
<a name="index-exporting-keying-material"></a>
<a name="index-deriving-keys"></a>
<a name="index-key-extraction"></a>

<p>In several cases, after a TLS connection is established, it is desirable
to derive keys to be used in another application or protocol (e.g., in an
other TLS session using pre-shared keys). The following describe GnuTLS&rsquo;
implementation of RFC5705 to extract keys based on a session&rsquo;s master secret.
</p>
<p>The API to use is <a href="#gnutls_005fprf">gnutls_prf</a>.  The 
function needs to be provided with a label,
and additional context data to mix in the <code>extra</code> parameter. 
Moreover, the API allows to switch the mix of the
client and server random nonces, using the <code>server_random_first</code> parameter.
In typical uses you don&rsquo;t need it, so a zero value should be provided in <code>server_random_first</code>.
</p>
<p>For example, after establishing a TLS session using
<a href="#gnutls_005fhandshake">gnutls_handshake</a>, you can obtain 32-bytes to be used as key, using this call:
</p>
<div class="example">
<pre class="example">#define MYLABEL &quot;EXPORTER-My-protocol-name&quot;
#define MYCONTEXT &quot;my-protocol's-1st-session&quot;

char out[32];
rc = gnutls_prf (session, sizeof(MYLABEL)-1, MYLABEL, 0,
                 sizeof(MYCONTEXT)-1, MYCONTEXT, 32, out);
</pre></div>

<p>The output key depends on TLS&rsquo; master secret, and is the same on both client
and server.
</p>
<p>If you don&rsquo;t want to use the RFC5705 interface and not mix in the client and server random
nonces, there is a low-level TLS PRF interface called <a href="#gnutls_005fprf_005fraw">gnutls_prf_raw</a>.
</p>
<hr>
<a name="Channel-Bindings"></a>
<div class="header">
<p>
Next: <a href="#Interoperability" accesskey="n" rel="next">Interoperability</a>, Previous: <a href="#Deriving-keys-for-other-applications_002fprotocols" accesskey="p" rel="prev">Deriving keys for other applications/protocols</a>, Up: <a href="#Advanced-topics" accesskey="u" rel="up">Advanced topics</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Channel-bindings"></a>
<h4 class="subsection">6.12.6 Channel bindings</h4>
<a name="index-channel-bindings"></a>

<p>In user authentication protocols (e.g., EAP or SASL mechanisms) it is
useful to have a unique string that identifies the secure channel that
is used, to bind together the user authentication with the secure
channel.  This can protect against man-in-the-middle attacks in some
situations.  That unique string is called a &ldquo;channel binding&rdquo;.  For
background and discussion see [<em>RFC5056</em>].
</p>
<p>In <acronym>GnuTLS</acronym> you can extract a channel binding using the
<a href="#gnutls_005fsession_005fchannel_005fbinding">gnutls_session_channel_binding</a> function.  Currently only the
type <code>GNUTLS_CB_TLS_UNIQUE</code> is supported, which corresponds to
the <code>tls-unique</code> channel binding for TLS defined in
[<em>RFC5929</em>].
</p>
<p>The following example describes how to print the channel binding data.
Note that it must be run after a successful TLS handshake.
</p>
<div class="example">
<pre class="example">{
  gnutls_datum_t cb;
  int rc;

  rc = gnutls_session_channel_binding (session,
                                       GNUTLS_CB_TLS_UNIQUE,
                                       &amp;cb);
  if (rc)
    fprintf (stderr, &quot;Channel binding error: %s\n&quot;,
             gnutls_strerror (rc));
  else
    {
      size_t i;
      printf (&quot;- Channel binding 'tls-unique': &quot;);
      for (i = 0; i &lt; cb.size; i++)
        printf (&quot;%02x&quot;, cb.data[i]);
      printf (&quot;\n&quot;);
    }
}
</pre></div>

<hr>
<a name="Interoperability"></a>
<div class="header">
<p>
Next: <a href="#Compatibility-with-the-OpenSSL-library" accesskey="n" rel="next">Compatibility with the OpenSSL library</a>, Previous: <a href="#Channel-Bindings" accesskey="p" rel="prev">Channel Bindings</a>, Up: <a href="#Advanced-topics" accesskey="u" rel="up">Advanced topics</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Interoperability-1"></a>
<h4 class="subsection">6.12.7 Interoperability</h4>

<p>The <acronym>TLS</acronym> protocols support many ciphersuites, extensions and version
numbers. As a result, few implementations are 
not able to properly interoperate once faced with extensions or version protocols
they do not support and understand. The <acronym>TLS</acronym> protocol allows for a
graceful downgrade to the commonly supported options, but practice shows 
it is not always implemented correctly. 
</p>
<p>Because there is no way to achieve maximum interoperability with broken peers
without sacrificing security, <acronym>GnuTLS</acronym> ignores such peers by default. 
This might not be acceptable in cases where maximum compatibility
is required. Thus we allow enabling compatibility with broken peers using
priority strings (see <a href="#Priority-Strings">Priority Strings</a>). A conservative priority
string that would disable certain <acronym>TLS</acronym> protocol
options that are known to cause compatibility problems, is shown below. 
</p><pre class="verbatim">NORMAL:%COMPAT
</pre>
<p>For very old broken peers that do not tolerate TLS version numbers over TLS 1.0
another priority string is:
</p><pre class="verbatim">NORMAL:-VERS-TLS-ALL:+VERS-TLS1.0:+VERS-SSL3.0:%COMPAT
</pre><p>This priority string will in addition to above, only enable SSL 3.0 and 
TLS 1.0 as protocols. 
</p>

<hr>
<a name="Compatibility-with-the-OpenSSL-library"></a>
<div class="header">
<p>
Previous: <a href="#Interoperability" accesskey="p" rel="prev">Interoperability</a>, Up: <a href="#Advanced-topics" accesskey="u" rel="up">Advanced topics</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Compatibility-with-the-OpenSSL-library-1"></a>
<h4 class="subsection">6.12.8 Compatibility with the OpenSSL library</h4>
<a name="index-OpenSSL"></a>

<p>To ease <acronym>GnuTLS</acronym>&rsquo; integration with existing applications, a
compatibility layer with the OpenSSL library is included
in the <code>gnutls-openssl</code> library. This compatibility layer is not
complete and it is not intended to completely re-implement the OpenSSL
API with <acronym>GnuTLS</acronym>.  It only provides limited source-level
compatibility. 
</p>
<p>The prototypes for the compatibility functions are in the
<samp>gnutls/openssl.h</samp> header file. The limitations 
imposed by the compatibility layer include:
</p>
<ul>
<li> Error handling is not thread safe.

</li></ul>


<hr>
<a name="GnuTLS-application-examples"></a>
<div class="header">
<p>
Next: <a href="#Using-GnuTLS-as-a-cryptographic-library" accesskey="n" rel="next">Using GnuTLS as a cryptographic library</a>, Previous: <a href="#How-to-use-GnuTLS-in-applications" accesskey="p" rel="prev">How to use GnuTLS in applications</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="GnuTLS-application-examples-1"></a>
<h2 class="chapter">7 GnuTLS application examples</h2>
<a name="examples"></a><a name="index-example-programs"></a>
<a name="index-examples"></a>

<p>In this chapter several examples of real-world use cases are listed.
The examples are simplified to promote readability and contain little or 
no error checking.  
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Client-examples" accesskey="1">Client examples</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Server-examples" accesskey="2">Server examples</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OCSP-example" accesskey="3">OCSP example</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Miscellaneous-examples" accesskey="4">Miscellaneous examples</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Client-examples"></a>
<div class="header">
<p>
Next: <a href="#Server-examples" accesskey="n" rel="next">Server examples</a>, Up: <a href="#GnuTLS-application-examples" accesskey="u" rel="up">GnuTLS application examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Client-examples-1"></a>
<h3 class="section">7.1 Client examples</h3>

<p>This section contains examples of <acronym>TLS</acronym> and <acronym>SSL</acronym>
clients, using <acronym>GnuTLS</acronym>. Note that some of the examples require functions
implemented by another example.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Simple-client-example-with-X_002e509-certificate-support" accesskey="1">Simple client example with X.509 certificate support</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Simple-client-example-with-SSH_002dstyle-certificate-verification" accesskey="2">Simple client example with SSH-style certificate verification</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Simple-client-example-with-anonymous-authentication" accesskey="3">Simple client example with anonymous authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Simple-Datagram-TLS-client-example" accesskey="4">Simple Datagram TLS client example</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Obtaining-session-information" accesskey="5">Obtaining session information</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Using-a-callback-to-select-the-certificate-to-use" accesskey="6">Using a callback to select the certificate to use</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Verifying-a-certificate" accesskey="7">Verifying a certificate</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Client-using-a-smart-card-with-TLS" accesskey="8">Client using a smart card with TLS</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Client-with-Resume-capability-example" accesskey="9">Client with Resume capability example</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Simple-client-example-with-SRP-authentication">Simple client example with SRP authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Simple-client-example-in-C_002b_002b">Simple client example in C++</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Helper-functions-for-TCP-connections">Helper functions for TCP connections</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Helper-functions-for-UDP-connections">Helper functions for UDP connections</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Simple-client-example-with-X_002e509-certificate-support"></a>
<div class="header">
<p>
Next: <a href="#Simple-client-example-with-SSH_002dstyle-certificate-verification" accesskey="n" rel="next">Simple client example with SSH-style certificate verification</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Simple-client-example-with-X_002e509-certificate-support-1"></a>
<h4 class="subsection">7.1.1 Simple client example with <acronym>X.509</acronym> certificate support</h4>
<a name="ex_002dverify"></a>
<p>Let&rsquo;s assume now that we want to create a TCP client which
communicates with servers that use <acronym>X.509</acronym> or
<acronym>OpenPGP</acronym> certificate authentication. The following client is
a very simple <acronym>TLS</acronym> client, which uses the high level verification
functions for certificates, but does not support session
resumption. 
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/x509.h&gt;
#include &quot;examples.h&quot;

/* A very basic TLS client, with X.509 authentication and server certificate
 * verification. Note that error checking for missing files etc. is omitted
 * for simplicity.
 */

#define MAX_BUF 1024
#define CAFILE &quot;/etc/ssl/certs/ca-certificates.crt&quot;
#define MSG &quot;GET / HTTP/1.0\r\n\r\n&quot;

extern int tcp_connect(void);
extern void tcp_close(int sd);

int main(void)
{
        int ret, sd, ii;
        gnutls_session_t session;
        char buffer[MAX_BUF + 1];
        gnutls_datum_t out;
        int type;
        unsigned status;
#if 0
        const char *err;
#endif
        gnutls_certificate_credentials_t xcred;

        if (gnutls_check_version(&quot;3.4.6&quot;) == NULL) {
                fprintf(stderr, &quot;GnuTLS 3.4.6 or later is required for this example\n&quot;);
                exit(1);
        }

        /* for backwards compatibility with gnutls &lt; 3.3.0 */
        gnutls_global_init();

        /* X509 stuff */
        gnutls_certificate_allocate_credentials(&amp;xcred);

        /* sets the trusted cas file
         */
        gnutls_certificate_set_x509_trust_file(xcred, CAFILE,
                                               GNUTLS_X509_FMT_PEM);

        /* If client holds a certificate it can be set using the following:
         *
         gnutls_certificate_set_x509_key_file (xcred, 
         &quot;cert.pem&quot;, &quot;key.pem&quot;, 
         GNUTLS_X509_FMT_PEM); 
         */

        /* Initialize TLS session 
         */
        gnutls_init(&amp;session, GNUTLS_CLIENT);

        gnutls_session_set_ptr(session, (void *) &quot;my_host_name&quot;);

        gnutls_server_name_set(session, GNUTLS_NAME_DNS, &quot;my_host_name&quot;,
                               strlen(&quot;my_host_name&quot;));

        /* It is recommended to use the default priorities */
        gnutls_set_default_priority(session);
#if 0
	/* if more fine-graned control is required */
        ret = gnutls_priority_set_direct(session, 
                                         &quot;NORMAL&quot;, &amp;err);
        if (ret &lt; 0) {
                if (ret == GNUTLS_E_INVALID_REQUEST) {
                        fprintf(stderr, &quot;Syntax error at: %s\n&quot;, err);
                }
                exit(1);
        }
#endif

        /* put the x509 credentials to the current session
         */
        gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, xcred);
        gnutls_session_set_verify_cert(session, &quot;my_host_name&quot;, 0);

        /* connect to the peer
         */
        sd = tcp_connect();

        gnutls_transport_set_int(session, sd);
        gnutls_handshake_set_timeout(session,
                                     GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);

        /* Perform the TLS handshake
         */
        do {
                ret = gnutls_handshake(session);
        }
        while (ret &lt; 0 &amp;&amp; gnutls_error_is_fatal(ret) == 0);
        if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Handshake failed\n&quot;);
                gnutls_perror(ret);
                goto end;
        } else {
                char *desc;

                desc = gnutls_session_get_desc(session);
                printf(&quot;- Session info: %s\n&quot;, desc);
                gnutls_free(desc);
        }

        /* check certificate verification status */
        type = gnutls_certificate_type_get(session);
        status = gnutls_session_get_verify_cert_status(session);
        ret =
            gnutls_certificate_verification_status_print(status, type,
                                                         &amp;out, 0);
        if (ret &lt; 0) {
                printf(&quot;Error\n&quot;);
                return GNUTLS_E_CERTIFICATE_ERROR;
        }

        printf(&quot;%s&quot;, out.data);
        gnutls_free(out.data);

	/* send data */
        gnutls_record_send(session, MSG, strlen(MSG));

        ret = gnutls_record_recv(session, buffer, MAX_BUF);
        if (ret == 0) {
                printf(&quot;- Peer has closed the TLS connection\n&quot;);
                goto end;
        } else if (ret &lt; 0 &amp;&amp; gnutls_error_is_fatal(ret) == 0) {
                fprintf(stderr, &quot;*** Warning: %s\n&quot;, gnutls_strerror(ret));
        } else if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Error: %s\n&quot;, gnutls_strerror(ret));
                goto end;
        }

        if (ret &gt; 0) {
                printf(&quot;- Received %d bytes: &quot;, ret);
                for (ii = 0; ii &lt; ret; ii++) {
                        fputc(buffer[ii], stdout);
                }
                fputs(&quot;\n&quot;, stdout);
        }

        gnutls_bye(session, GNUTLS_SHUT_RDWR);

      end:

        tcp_close(sd);

        gnutls_deinit(session);

        gnutls_certificate_free_credentials(xcred);

        gnutls_global_deinit();

        return 0;
}
</pre>
<hr>
<a name="Simple-client-example-with-SSH_002dstyle-certificate-verification"></a>
<div class="header">
<p>
Next: <a href="#Simple-client-example-with-anonymous-authentication" accesskey="n" rel="next">Simple client example with anonymous authentication</a>, Previous: <a href="#Simple-client-example-with-X_002e509-certificate-support" accesskey="p" rel="prev">Simple client example with X.509 certificate support</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Simple-client-example-with-SSH_002dstyle-certificate-verification-1"></a>
<h4 class="subsection">7.1.2 Simple client example with SSH-style certificate verification</h4>

<p>This is an alternative verification function that will use the
X.509 certificate authorities for verification, but also assume an
trust on first use (SSH-like) authentication system. That is the user is 
prompted on unknown public keys and known public keys are considered 
trusted.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/x509.h&gt;
#include &quot;examples.h&quot;

/* This function will verify the peer's certificate, check
 * if the hostname matches. In addition it will perform an
 * SSH-style authentication, where ultimately trusted keys
 * are only the keys that have been seen before.
 */
int _ssh_verify_certificate_callback(gnutls_session_t session)
{
        unsigned int status;
        const gnutls_datum_t *cert_list;
        unsigned int cert_list_size;
        int ret, type;
        gnutls_datum_t out;
        const char *hostname;

        /* read hostname */
        hostname = gnutls_session_get_ptr(session);

        /* This verification function uses the trusted CAs in the credentials
         * structure. So you must have installed one or more CA certificates.
         */
        ret = gnutls_certificate_verify_peers3(session, hostname, &amp;status);
        if (ret &lt; 0) {
                printf(&quot;Error\n&quot;);
                return GNUTLS_E_CERTIFICATE_ERROR;
        }

        type = gnutls_certificate_type_get(session);

        ret =
            gnutls_certificate_verification_status_print(status, type,
                                                         &amp;out, 0);
        if (ret &lt; 0) {
                printf(&quot;Error\n&quot;);
                return GNUTLS_E_CERTIFICATE_ERROR;
        }

        printf(&quot;%s&quot;, out.data);

        gnutls_free(out.data);

        if (status != 0)        /* Certificate is not trusted */
                return GNUTLS_E_CERTIFICATE_ERROR;

        /* Do SSH verification */
        cert_list = gnutls_certificate_get_peers(session, &amp;cert_list_size);
        if (cert_list == NULL) {
                printf(&quot;No certificate was found!\n&quot;);
                return GNUTLS_E_CERTIFICATE_ERROR;
        }

        /* service may be obtained alternatively using getservbyport() */
        ret = gnutls_verify_stored_pubkey(NULL, NULL, hostname, &quot;https&quot;,
                                          type, &amp;cert_list[0], 0);
        if (ret == GNUTLS_E_NO_CERTIFICATE_FOUND) {
                printf(&quot;Host %s is not known.&quot;, hostname);
                if (status == 0)
                        printf(&quot;Its certificate is valid for %s.\n&quot;,
                               hostname);

                /* the certificate must be printed and user must be asked on
                 * whether it is trustworthy. --see gnutls_x509_crt_print() */

                /* if not trusted */
                return GNUTLS_E_CERTIFICATE_ERROR;
        } else if (ret == GNUTLS_E_CERTIFICATE_KEY_MISMATCH) {
                printf
                    (&quot;Warning: host %s is known but has another key associated.&quot;,
                     hostname);
                printf
                    (&quot;It might be that the server has multiple keys, or you are under attack\n&quot;);
                if (status == 0)
                        printf(&quot;Its certificate is valid for %s.\n&quot;,
                               hostname);

                /* the certificate must be printed and user must be asked on
                 * whether it is trustworthy. --see gnutls_x509_crt_print() */

                /* if not trusted */
                return GNUTLS_E_CERTIFICATE_ERROR;
        } else if (ret &lt; 0) {
                printf(&quot;gnutls_verify_stored_pubkey: %s\n&quot;,
                       gnutls_strerror(ret));
                return ret;
        }

        /* user trusts the key -&gt; store it */
        if (ret != 0) {
                ret = gnutls_store_pubkey(NULL, NULL, hostname, &quot;https&quot;,
                                          type, &amp;cert_list[0], 0, 0);
                if (ret &lt; 0)
                        printf(&quot;gnutls_store_pubkey: %s\n&quot;,
                               gnutls_strerror(ret));
        }

        /* notify gnutls to continue handshake normally */
        return 0;
}
</pre>
<hr>
<a name="Simple-client-example-with-anonymous-authentication"></a>
<div class="header">
<p>
Next: <a href="#Simple-Datagram-TLS-client-example" accesskey="n" rel="next">Simple Datagram TLS client example</a>, Previous: <a href="#Simple-client-example-with-SSH_002dstyle-certificate-verification" accesskey="p" rel="prev">Simple client example with SSH-style certificate verification</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Simple-client-example-with-anonymous-authentication-1"></a>
<h4 class="subsection">7.1.3 Simple client example with anonymous authentication</h4>

<p>The simplest client using TLS is the one that doesn&rsquo;t do any
authentication.  This means no external certificates or passwords are
needed to set up the connection.  As could be expected, the connection
is vulnerable to man-in-the-middle (active or redirection) attacks.
However, the data are integrity protected and encrypted from
passive eavesdroppers.
</p>
<p>Note that due to the vulnerable nature of this method very few public
servers support it.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;arpa/inet.h&gt;
#include &lt;unistd.h&gt;
#include &lt;gnutls/gnutls.h&gt;

/* A very basic TLS client, with anonymous authentication.
 */

#define MAX_BUF 1024
#define MSG &quot;GET / HTTP/1.0\r\n\r\n&quot;

extern int tcp_connect(void);
extern void tcp_close(int sd);

int main(void)
{
        int ret, sd, ii;
        gnutls_session_t session;
        char buffer[MAX_BUF + 1];
        gnutls_anon_client_credentials_t anoncred;
        /* Need to enable anonymous KX specifically. */

        gnutls_global_init();

        gnutls_anon_allocate_client_credentials(&amp;anoncred);

        /* Initialize TLS session 
         */
        gnutls_init(&amp;session, GNUTLS_CLIENT);

        /* Use default priorities */
        gnutls_priority_set_direct(session,
                                   &quot;PERFORMANCE:+ANON-ECDH:+ANON-DH&quot;,
                                   NULL);

        /* put the anonymous credentials to the current session
         */
        gnutls_credentials_set(session, GNUTLS_CRD_ANON, anoncred);

        /* connect to the peer
         */
        sd = tcp_connect();

        gnutls_transport_set_int(session, sd);
        gnutls_handshake_set_timeout(session,
                                     GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);

        /* Perform the TLS handshake
         */
        do {
                ret = gnutls_handshake(session);
        }
        while (ret &lt; 0 &amp;&amp; gnutls_error_is_fatal(ret) == 0);

        if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Handshake failed\n&quot;);
                gnutls_perror(ret);
                goto end;
        } else {
                char *desc;

                desc = gnutls_session_get_desc(session);
                printf(&quot;- Session info: %s\n&quot;, desc);
                gnutls_free(desc);
        }

        gnutls_record_send(session, MSG, strlen(MSG));

        ret = gnutls_record_recv(session, buffer, MAX_BUF);
        if (ret == 0) {
                printf(&quot;- Peer has closed the TLS connection\n&quot;);
                goto end;
        } else if (ret &lt; 0 &amp;&amp; gnutls_error_is_fatal(ret) == 0) {
                fprintf(stderr, &quot;*** Warning: %s\n&quot;, gnutls_strerror(ret));
        } else if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Error: %s\n&quot;, gnutls_strerror(ret));
                goto end;
        }

        if (ret &gt; 0) {
                printf(&quot;- Received %d bytes: &quot;, ret);
                for (ii = 0; ii &lt; ret; ii++) {
                        fputc(buffer[ii], stdout);
                }
                fputs(&quot;\n&quot;, stdout);
        }

        gnutls_bye(session, GNUTLS_SHUT_RDWR);

      end:

        tcp_close(sd);

        gnutls_deinit(session);

        gnutls_anon_free_client_credentials(anoncred);

        gnutls_global_deinit();

        return 0;
}
</pre>

<hr>
<a name="Simple-Datagram-TLS-client-example"></a>
<div class="header">
<p>
Next: <a href="#Obtaining-session-information" accesskey="n" rel="next">Obtaining session information</a>, Previous: <a href="#Simple-client-example-with-anonymous-authentication" accesskey="p" rel="prev">Simple client example with anonymous authentication</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Simple-datagram-TLS-client-example"></a>
<h4 class="subsection">7.1.4 Simple datagram <acronym>TLS</acronym> client example</h4>

<p>This is a client that uses <acronym>UDP</acronym> to connect to a
server. This is the <acronym>DTLS</acronym> equivalent to the TLS example
with X.509 certificates.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;arpa/inet.h&gt;
#include &lt;unistd.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/dtls.h&gt;

/* A very basic Datagram TLS client, over UDP with X.509 authentication.
 */

#define MAX_BUF 1024
#define CAFILE &quot;/etc/ssl/certs/ca-certificates.crt&quot;
#define MSG &quot;GET / HTTP/1.0\r\n\r\n&quot;

extern int udp_connect(void);
extern void udp_close(int sd);
extern int verify_certificate_callback(gnutls_session_t session);

int main(void)
{
        int ret, sd, ii;
        gnutls_session_t session;
        char buffer[MAX_BUF + 1];
        const char *err;
        gnutls_certificate_credentials_t xcred;

        if (gnutls_check_version(&quot;3.1.4&quot;) == NULL) {
                fprintf(stderr, &quot;GnuTLS 3.1.4 or later is required for this example\n&quot;);
                exit(1);
        }

        /* for backwards compatibility with gnutls &lt; 3.3.0 */
        gnutls_global_init();

        /* X509 stuff */
        gnutls_certificate_allocate_credentials(&amp;xcred);

        /* sets the trusted cas file */
        gnutls_certificate_set_x509_trust_file(xcred, CAFILE,
                                               GNUTLS_X509_FMT_PEM);
        gnutls_certificate_set_verify_function(xcred,
                                               verify_certificate_callback);

        /* Initialize TLS session */
        gnutls_init(&amp;session, GNUTLS_CLIENT | GNUTLS_DATAGRAM);

        /* Use default priorities */
        ret = gnutls_priority_set_direct(session, 
                                         &quot;NORMAL&quot;, &amp;err);
        if (ret &lt; 0) {
                if (ret == GNUTLS_E_INVALID_REQUEST) {
                        fprintf(stderr, &quot;Syntax error at: %s\n&quot;, err);
                }
                exit(1);
        }

        /* put the x509 credentials to the current session */
        gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, xcred);
        gnutls_server_name_set(session, GNUTLS_NAME_DNS, &quot;my_host_name&quot;,
                               strlen(&quot;my_host_name&quot;));

        /* connect to the peer */
        sd = udp_connect();

        gnutls_transport_set_int(session, sd);

        /* set the connection MTU */
        gnutls_dtls_set_mtu(session, 1000);
        /* gnutls_dtls_set_timeouts(session, 1000, 60000); */

        /* Perform the TLS handshake */
        do {
                ret = gnutls_handshake(session);
        }
        while (ret == GNUTLS_E_INTERRUPTED || ret == GNUTLS_E_AGAIN);
        /* Note that DTLS may also receive GNUTLS_E_LARGE_PACKET */

        if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Handshake failed\n&quot;);
                gnutls_perror(ret);
                goto end;
        } else {
                char *desc;

                desc = gnutls_session_get_desc(session);
                printf(&quot;- Session info: %s\n&quot;, desc);
                gnutls_free(desc);
        }

        gnutls_record_send(session, MSG, strlen(MSG));

        ret = gnutls_record_recv(session, buffer, MAX_BUF);
        if (ret == 0) {
                printf(&quot;- Peer has closed the TLS connection\n&quot;);
                goto end;
        } else if (ret &lt; 0 &amp;&amp; gnutls_error_is_fatal(ret) == 0) {
                fprintf(stderr, &quot;*** Warning: %s\n&quot;, gnutls_strerror(ret));
        } else if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Error: %s\n&quot;, gnutls_strerror(ret));
                goto end;
        }

        if (ret &gt; 0) {
                printf(&quot;- Received %d bytes: &quot;, ret);
                for (ii = 0; ii &lt; ret; ii++) {
                        fputc(buffer[ii], stdout);
                }
                fputs(&quot;\n&quot;, stdout);
        }

        /* It is suggested not to use GNUTLS_SHUT_RDWR in DTLS
         * connections because the peer's closure message might
         * be lost */
        gnutls_bye(session, GNUTLS_SHUT_WR);

      end:

        udp_close(sd);

        gnutls_deinit(session);

        gnutls_certificate_free_credentials(xcred);

        gnutls_global_deinit();

        return 0;
}
</pre>
<hr>
<a name="Obtaining-session-information"></a>
<div class="header">
<p>
Next: <a href="#Using-a-callback-to-select-the-certificate-to-use" accesskey="n" rel="next">Using a callback to select the certificate to use</a>, Previous: <a href="#Simple-Datagram-TLS-client-example" accesskey="p" rel="prev">Simple Datagram TLS client example</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Obtaining-session-information-1"></a>
<h4 class="subsection">7.1.5 Obtaining session information</h4>

<p>Most of the times it is desirable to know the security properties of
the current established session.  This includes the underlying ciphers
and the protocols involved.  That is the purpose of the following
function.  Note that this function will print meaningful values only
if called after a successful <a href="#gnutls_005fhandshake">gnutls_handshake</a>.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/x509.h&gt;

#include &quot;examples.h&quot;

/* This function will print some details of the
 * given session.
 */
int print_info(gnutls_session_t session)
{
        const char *tmp;
        gnutls_credentials_type_t cred;
        gnutls_kx_algorithm_t kx;
        int dhe, ecdh;

        dhe = ecdh = 0;

        /* print the key exchange's algorithm name
         */
        kx = gnutls_kx_get(session);
        tmp = gnutls_kx_get_name(kx);
        printf(&quot;- Key Exchange: %s\n&quot;, tmp);

        /* Check the authentication type used and switch
         * to the appropriate.
         */
        cred = gnutls_auth_get_type(session);
        switch (cred) {
        case GNUTLS_CRD_IA:
                printf(&quot;- TLS/IA session\n&quot;);
                break;


#ifdef ENABLE_SRP
        case GNUTLS_CRD_SRP:
                printf(&quot;- SRP session with username %s\n&quot;,
                       gnutls_srp_server_get_username(session));
                break;
#endif

        case GNUTLS_CRD_PSK:
                /* This returns NULL in server side.
                 */
                if (gnutls_psk_client_get_hint(session) != NULL)
                        printf(&quot;- PSK authentication. PSK hint '%s'\n&quot;,
                               gnutls_psk_client_get_hint(session));
                /* This returns NULL in client side.
                 */
                if (gnutls_psk_server_get_username(session) != NULL)
                        printf(&quot;- PSK authentication. Connected as '%s'\n&quot;,
                               gnutls_psk_server_get_username(session));

                if (kx == GNUTLS_KX_ECDHE_PSK)
                        ecdh = 1;
                else if (kx == GNUTLS_KX_DHE_PSK)
                        dhe = 1;
                break;

        case GNUTLS_CRD_ANON:  /* anonymous authentication */

                printf(&quot;- Anonymous authentication.\n&quot;);
                if (kx == GNUTLS_KX_ANON_ECDH)
                        ecdh = 1;
                else if (kx == GNUTLS_KX_ANON_DH)
                        dhe = 1;
                break;

        case GNUTLS_CRD_CERTIFICATE:   /* certificate authentication */

                /* Check if we have been using ephemeral Diffie-Hellman.
                 */
                if (kx == GNUTLS_KX_DHE_RSA || kx == GNUTLS_KX_DHE_DSS)
                        dhe = 1;
                else if (kx == GNUTLS_KX_ECDHE_RSA
                         || kx == GNUTLS_KX_ECDHE_ECDSA)
                        ecdh = 1;

                /* if the certificate list is available, then
                 * print some information about it.
                 */
                print_x509_certificate_info(session);

        }                       /* switch */

        if (ecdh != 0)
                printf(&quot;- Ephemeral ECDH using curve %s\n&quot;,
                       gnutls_ecc_curve_get_name(gnutls_ecc_curve_get
                                                 (session)));
        else if (dhe != 0)
                printf(&quot;- Ephemeral DH using prime of %d bits\n&quot;,
                       gnutls_dh_get_prime_bits(session));

        /* print the protocol's name (ie TLS 1.0) 
         */
        tmp =
            gnutls_protocol_get_name(gnutls_protocol_get_version(session));
        printf(&quot;- Protocol: %s\n&quot;, tmp);

        /* print the certificate type of the peer.
         * ie X.509
         */
        tmp =
            gnutls_certificate_type_get_name(gnutls_certificate_type_get
                                             (session));

        printf(&quot;- Certificate Type: %s\n&quot;, tmp);

        /* print the compression algorithm (if any)
         */
        tmp = gnutls_compression_get_name(gnutls_compression_get(session));
        printf(&quot;- Compression: %s\n&quot;, tmp);

        /* print the name of the cipher used.
         * ie 3DES.
         */
        tmp = gnutls_cipher_get_name(gnutls_cipher_get(session));
        printf(&quot;- Cipher: %s\n&quot;, tmp);

        /* Print the MAC algorithms name.
         * ie SHA1
         */
        tmp = gnutls_mac_get_name(gnutls_mac_get(session));
        printf(&quot;- MAC: %s\n&quot;, tmp);

        return 0;
}
</pre>
<hr>
<a name="Using-a-callback-to-select-the-certificate-to-use"></a>
<div class="header">
<p>
Next: <a href="#Verifying-a-certificate" accesskey="n" rel="next">Verifying a certificate</a>, Previous: <a href="#Obtaining-session-information" accesskey="p" rel="prev">Obtaining session information</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Using-a-callback-to-select-the-certificate-to-use-1"></a>
<h4 class="subsection">7.1.6 Using a callback to select the certificate to use</h4>

<p>There are cases where a client holds several certificate and key
pairs, and may not want to load all of them in the credentials
structure.  The following example demonstrates the use of the
certificate selection callback.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;arpa/inet.h&gt;
#include &lt;unistd.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/x509.h&gt;
#include &lt;gnutls/abstract.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/stat.h&gt;
#include &lt;fcntl.h&gt;

/* A TLS client that loads the certificate and key.
 */

#define MAX_BUF 1024
#define MSG &quot;GET / HTTP/1.0\r\n\r\n&quot;

#define CERT_FILE &quot;cert.pem&quot;
#define KEY_FILE &quot;key.pem&quot;
#define CAFILE &quot;/etc/ssl/certs/ca-certificates.crt&quot;

extern int tcp_connect(void);
extern void tcp_close(int sd);

static int
cert_callback(gnutls_session_t session,
              const gnutls_datum_t * req_ca_rdn, int nreqs,
              const gnutls_pk_algorithm_t * sign_algos,
              int sign_algos_length, gnutls_pcert_st ** pcert,
              unsigned int *pcert_length, gnutls_privkey_t * pkey);

gnutls_pcert_st pcrt;
gnutls_privkey_t key;

/* Load the certificate and the private key.
 */
static void load_keys(void)
{
        int ret;
        gnutls_datum_t data;

        ret = gnutls_load_file(CERT_FILE, &amp;data);
        if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Error loading certificate file.\n&quot;);
                exit(1);
        }

        ret =
            gnutls_pcert_import_x509_raw(&amp;pcrt, &amp;data, GNUTLS_X509_FMT_PEM,
                                         0);
        if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Error loading certificate file: %s\n&quot;,
                        gnutls_strerror(ret));
                exit(1);
        }

        gnutls_free(data.data);

        ret = gnutls_load_file(KEY_FILE, &amp;data);
        if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Error loading key file.\n&quot;);
                exit(1);
        }

        gnutls_privkey_init(&amp;key);

        ret =
            gnutls_privkey_import_x509_raw(key, &amp;data, GNUTLS_X509_FMT_PEM,
                                           NULL, 0);
        if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Error loading key file: %s\n&quot;,
                        gnutls_strerror(ret));
                exit(1);
        }

        gnutls_free(data.data);
}

int main(void)
{
        int ret, sd, ii;
        gnutls_session_t session;
        gnutls_priority_t priorities_cache;
        char buffer[MAX_BUF + 1];
        gnutls_certificate_credentials_t xcred;
        
        if (gnutls_check_version(&quot;3.1.4&quot;) == NULL) {
                fprintf(stderr, &quot;GnuTLS 3.1.4 or later is required for this example\n&quot;);
                exit(1);
        }

        /* for backwards compatibility with gnutls &lt; 3.3.0 */
        gnutls_global_init();

        load_keys();

        /* X509 stuff */
        gnutls_certificate_allocate_credentials(&amp;xcred);

        /* priorities */
        gnutls_priority_init(&amp;priorities_cache, 
                             &quot;NORMAL&quot;, NULL);

        /* sets the trusted cas file
         */
        gnutls_certificate_set_x509_trust_file(xcred, CAFILE,
                                               GNUTLS_X509_FMT_PEM);

        gnutls_certificate_set_retrieve_function2(xcred, cert_callback);

        /* Initialize TLS session 
         */
        gnutls_init(&amp;session, GNUTLS_CLIENT);

        /* Use default priorities */
        gnutls_priority_set(session, priorities_cache);

        /* put the x509 credentials to the current session
         */
        gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, xcred);

        /* connect to the peer
         */
        sd = tcp_connect();

        gnutls_transport_set_int(session, sd);

        /* Perform the TLS handshake
         */
        ret = gnutls_handshake(session);

        if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Handshake failed\n&quot;);
                gnutls_perror(ret);
                goto end;
        } else {
                char *desc;

                desc = gnutls_session_get_desc(session);
                printf(&quot;- Session info: %s\n&quot;, desc);
                gnutls_free(desc);
        }

        gnutls_record_send(session, MSG, strlen(MSG));

        ret = gnutls_record_recv(session, buffer, MAX_BUF);
        if (ret == 0) {
                printf(&quot;- Peer has closed the TLS connection\n&quot;);
                goto end;
        } else if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Error: %s\n&quot;, gnutls_strerror(ret));
                goto end;
        }

        printf(&quot;- Received %d bytes: &quot;, ret);
        for (ii = 0; ii &lt; ret; ii++) {
                fputc(buffer[ii], stdout);
        }
        fputs(&quot;\n&quot;, stdout);

        gnutls_bye(session, GNUTLS_SHUT_RDWR);

      end:

        tcp_close(sd);

        gnutls_deinit(session);

        gnutls_certificate_free_credentials(xcred);
        gnutls_priority_deinit(priorities_cache);

        gnutls_global_deinit();

        return 0;
}



/* This callback should be associated with a session by calling
 * gnutls_certificate_client_set_retrieve_function( session, cert_callback),
 * before a handshake.
 */

static int
cert_callback(gnutls_session_t session,
              const gnutls_datum_t * req_ca_rdn, int nreqs,
              const gnutls_pk_algorithm_t * sign_algos,
              int sign_algos_length, gnutls_pcert_st ** pcert,
              unsigned int *pcert_length, gnutls_privkey_t * pkey)
{
        char issuer_dn[256];
        int i, ret;
        size_t len;
        gnutls_certificate_type_t type;

        /* Print the server's trusted CAs
         */
        if (nreqs &gt; 0)
                printf(&quot;- Server's trusted authorities:\n&quot;);
        else
                printf
                    (&quot;- Server did not send us any trusted authorities names.\n&quot;);

        /* print the names (if any) */
        for (i = 0; i &lt; nreqs; i++) {
                len = sizeof(issuer_dn);
                ret = gnutls_x509_rdn_get(&amp;req_ca_rdn[i], issuer_dn, &amp;len);
                if (ret &gt;= 0) {
                        printf(&quot;   [%d]: &quot;, i);
                        printf(&quot;%s\n&quot;, issuer_dn);
                }
        }

        /* Select a certificate and return it.
         * The certificate must be of any of the &quot;sign algorithms&quot;
         * supported by the server.
         */
        type = gnutls_certificate_type_get(session);
        if (type == GNUTLS_CRT_X509) {
                *pcert_length = 1;
                *pcert = &amp;pcrt;
                *pkey = key;
        } else {
                return -1;
        }

        return 0;

}
</pre>
<hr>
<a name="Verifying-a-certificate"></a>
<div class="header">
<p>
Next: <a href="#Client-using-a-smart-card-with-TLS" accesskey="n" rel="next">Client using a smart card with TLS</a>, Previous: <a href="#Using-a-callback-to-select-the-certificate-to-use" accesskey="p" rel="prev">Using a callback to select the certificate to use</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Verifying-a-certificate-1"></a>
<h4 class="subsection">7.1.7 Verifying a certificate</h4>
<a name="ex_002dverify2"></a>
<p>An example is listed below which uses the high level verification
functions to verify a given certificate list.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/x509.h&gt;

#include &quot;examples.h&quot;

/* All the available CRLs
 */
gnutls_x509_crl_t *crl_list;
int crl_list_size;

/* All the available trusted CAs
 */
gnutls_x509_crt_t *ca_list;
int ca_list_size;

static int print_details_func(gnutls_x509_crt_t cert,
                              gnutls_x509_crt_t issuer,
                              gnutls_x509_crl_t crl,
                              unsigned int verification_output);

/* This function will try to verify the peer's certificate chain, and
 * also check if the hostname matches.
 */
void
verify_certificate_chain(const char *hostname,
                         const gnutls_datum_t * cert_chain,
                         int cert_chain_length)
{
        int i;
        gnutls_x509_trust_list_t tlist;
        gnutls_x509_crt_t *cert;

        unsigned int output;

        /* Initialize the trusted certificate list. This should be done
         * once on initialization. gnutls_x509_crt_list_import2() and
         * gnutls_x509_crl_list_import2() can be used to load them.
         */
        gnutls_x509_trust_list_init(&amp;tlist, 0);

        gnutls_x509_trust_list_add_cas(tlist, ca_list, ca_list_size, 0);
        gnutls_x509_trust_list_add_crls(tlist, crl_list, crl_list_size,
                                        GNUTLS_TL_VERIFY_CRL, 0);

        cert = malloc(sizeof(*cert) * cert_chain_length);

        /* Import all the certificates in the chain to
         * native certificate format.
         */
        for (i = 0; i &lt; cert_chain_length; i++) {
                gnutls_x509_crt_init(&amp;cert[i]);
                gnutls_x509_crt_import(cert[i], &amp;cert_chain[i],
                                       GNUTLS_X509_FMT_DER);
        }

        gnutls_x509_trust_list_verify_named_crt(tlist, cert[0], hostname,
                                                strlen(hostname),
                                                GNUTLS_VERIFY_DISABLE_CRL_CHECKS,
                                                &amp;output,
                                                print_details_func);

        /* if this certificate is not explicitly trusted verify against CAs 
         */
        if (output != 0) {
                gnutls_x509_trust_list_verify_crt(tlist, cert,
                                                  cert_chain_length, 0,
                                                  &amp;output,
                                                  print_details_func);
        }

        if (output &amp; GNUTLS_CERT_INVALID) {
                fprintf(stderr, &quot;Not trusted&quot;);

                if (output &amp; GNUTLS_CERT_SIGNER_NOT_FOUND)
                        fprintf(stderr, &quot;: no issuer was found&quot;);
                if (output &amp; GNUTLS_CERT_SIGNER_NOT_CA)
                        fprintf(stderr, &quot;: issuer is not a CA&quot;);
                if (output &amp; GNUTLS_CERT_NOT_ACTIVATED)
                        fprintf(stderr, &quot;: not yet activated\n&quot;);
                if (output &amp; GNUTLS_CERT_EXPIRED)
                        fprintf(stderr, &quot;: expired\n&quot;);

                fprintf(stderr, &quot;\n&quot;);
        } else
                fprintf(stderr, &quot;Trusted\n&quot;);

        /* Check if the name in the first certificate matches our destination!
         */
        if (!gnutls_x509_crt_check_hostname(cert[0], hostname)) {
                printf
                    (&quot;The certificate's owner does not match hostname '%s'\n&quot;,
                     hostname);
        }

        gnutls_x509_trust_list_deinit(tlist, 1);

        return;
}

static int
print_details_func(gnutls_x509_crt_t cert,
                   gnutls_x509_crt_t issuer, gnutls_x509_crl_t crl,
                   unsigned int verification_output)
{
        char name[512];
        char issuer_name[512];
        size_t name_size;
        size_t issuer_name_size;

        issuer_name_size = sizeof(issuer_name);
        gnutls_x509_crt_get_issuer_dn(cert, issuer_name,
                                      &amp;issuer_name_size);

        name_size = sizeof(name);
        gnutls_x509_crt_get_dn(cert, name, &amp;name_size);

        fprintf(stdout, &quot;\tSubject: %s\n&quot;, name);
        fprintf(stdout, &quot;\tIssuer: %s\n&quot;, issuer_name);

        if (issuer != NULL) {
                issuer_name_size = sizeof(issuer_name);
                gnutls_x509_crt_get_dn(issuer, issuer_name,
                                       &amp;issuer_name_size);

                fprintf(stdout, &quot;\tVerified against: %s\n&quot;, issuer_name);
        }

        if (crl != NULL) {
                issuer_name_size = sizeof(issuer_name);
                gnutls_x509_crl_get_issuer_dn(crl, issuer_name,
                                              &amp;issuer_name_size);

                fprintf(stdout, &quot;\tVerified against CRL of: %s\n&quot;,
                        issuer_name);
        }

        fprintf(stdout, &quot;\tVerification output: %x\n\n&quot;,
                verification_output);

        return 0;
}
</pre>
<hr>
<a name="Client-using-a-smart-card-with-TLS"></a>
<div class="header">
<p>
Next: <a href="#Client-with-Resume-capability-example" accesskey="n" rel="next">Client with Resume capability example</a>, Previous: <a href="#Verifying-a-certificate" accesskey="p" rel="prev">Verifying a certificate</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Using-a-smart-card-with-TLS"></a>
<h4 class="subsection">7.1.8 Using a smart card with TLS</h4>
<a name="ex_002dpkcs11_002dclient"></a><a name="index-Smart-card-example"></a>

<p>This example will demonstrate how to load keys and certificates
from a smart-card or any other <acronym>PKCS</acronym> #11 token, and 
use it in a TLS connection.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;arpa/inet.h&gt;
#include &lt;unistd.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/x509.h&gt;
#include &lt;gnutls/pkcs11.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/stat.h&gt;
#include &lt;fcntl.h&gt;
#include &lt;getpass.h&gt;            /* for getpass() */

/* A TLS client that loads the certificate and key.
 */

#define MAX_BUF 1024
#define MSG &quot;GET / HTTP/1.0\r\n\r\n&quot;
#define MIN(x,y) (((x)&lt;(y))?(x):(y))

#define CAFILE &quot;/etc/ssl/certs/ca-certificates.crt&quot;

/* The URLs of the objects can be obtained
 * using p11tool --list-all --login
 */
#define KEY_URL &quot;pkcs11:manufacturer=SomeManufacturer;object=Private%20Key&quot; \
  &quot;;objecttype=private;id=%db%5b%3e%b5%72%33&quot;
#define CERT_URL &quot;pkcs11:manufacturer=SomeManufacturer;object=Certificate;&quot; \
  &quot;objecttype=cert;id=db%5b%3e%b5%72%33&quot;

extern int tcp_connect(void);
extern void tcp_close(int sd);

static int
pin_callback(void *user, int attempt, const char *token_url,
             const char *token_label, unsigned int flags, char *pin,
             size_t pin_max)
{
        const char *password;
        int len;

        printf(&quot;PIN required for token '%s' with URL '%s'\n&quot;, token_label,
               token_url);
        if (flags &amp; GNUTLS_PIN_FINAL_TRY)
                printf(&quot;*** This is the final try before locking!\n&quot;);
        if (flags &amp; GNUTLS_PIN_COUNT_LOW)
                printf(&quot;*** Only few tries left before locking!\n&quot;);
        if (flags &amp; GNUTLS_PIN_WRONG)
                printf(&quot;*** Wrong PIN\n&quot;);

        password = getpass(&quot;Enter pin: &quot;);
        if (password == NULL || password[0] == 0) {
                fprintf(stderr, &quot;No password given\n&quot;);
                exit(1);
        }

        len = MIN(pin_max - 1, strlen(password));
        memcpy(pin, password, len);
        pin[len] = 0;

        return 0;
}

int main(void)
{
        int ret, sd, ii;
        gnutls_session_t session;
        gnutls_priority_t priorities_cache;
        char buffer[MAX_BUF + 1];
        gnutls_certificate_credentials_t xcred;
        /* Allow connections to servers that have OpenPGP keys as well.
         */

        if (gnutls_check_version(&quot;3.1.4&quot;) == NULL) {
                fprintf(stderr, &quot;GnuTLS 3.1.4 or later is required for this example\n&quot;);
                exit(1);
        }

        /* for backwards compatibility with gnutls &lt; 3.3.0 */
        gnutls_global_init();

        /* The PKCS11 private key operations may require PIN.
         * Register a callback. */
        gnutls_pkcs11_set_pin_function(pin_callback, NULL);

        /* X509 stuff */
        gnutls_certificate_allocate_credentials(&amp;xcred);

        /* priorities */
        gnutls_priority_init(&amp;priorities_cache, 
                             &quot;NORMAL&quot;, NULL);

        /* sets the trusted cas file
         */
        gnutls_certificate_set_x509_trust_file(xcred, CAFILE,
                                               GNUTLS_X509_FMT_PEM);

        gnutls_certificate_set_x509_key_file(xcred, CERT_URL, KEY_URL,
                                             GNUTLS_X509_FMT_DER);

        /* Initialize TLS session
         */
        gnutls_init(&amp;session, GNUTLS_CLIENT);

        /* Use default priorities */
        gnutls_priority_set(session, priorities_cache);

        /* put the x509 credentials to the current session
         */
        gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, xcred);

        /* connect to the peer
         */
        sd = tcp_connect();

        gnutls_transport_set_int(session, sd);

        /* Perform the TLS handshake
         */
        ret = gnutls_handshake(session);

        if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Handshake failed\n&quot;);
                gnutls_perror(ret);
                goto end;
        } else {
                char *desc;

                desc = gnutls_session_get_desc(session);
                printf(&quot;- Session info: %s\n&quot;, desc);
                gnutls_free(desc);
        }

        gnutls_record_send(session, MSG, strlen(MSG));

        ret = gnutls_record_recv(session, buffer, MAX_BUF);
        if (ret == 0) {
                printf(&quot;- Peer has closed the TLS connection\n&quot;);
                goto end;
        } else if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Error: %s\n&quot;, gnutls_strerror(ret));
                goto end;
        }

        printf(&quot;- Received %d bytes: &quot;, ret);
        for (ii = 0; ii &lt; ret; ii++) {
                fputc(buffer[ii], stdout);
        }
        fputs(&quot;\n&quot;, stdout);

        gnutls_bye(session, GNUTLS_SHUT_RDWR);

      end:

        tcp_close(sd);

        gnutls_deinit(session);

        gnutls_certificate_free_credentials(xcred);
        gnutls_priority_deinit(priorities_cache);

        gnutls_global_deinit();

        return 0;
}
</pre>

<hr>
<a name="Client-with-Resume-capability-example"></a>
<div class="header">
<p>
Next: <a href="#Simple-client-example-with-SRP-authentication" accesskey="n" rel="next">Simple client example with SRP authentication</a>, Previous: <a href="#Client-using-a-smart-card-with-TLS" accesskey="p" rel="prev">Client using a smart card with TLS</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Client-with-resume-capability-example"></a>
<h4 class="subsection">7.1.9 Client with resume capability example</h4>
<a name="ex_002dresume_002dclient"></a>
<p>This is a modification of the simple client example. Here we
demonstrate the use of session resumption. The client tries to connect
once using <acronym>TLS</acronym>, close the connection and then try to
establish a new connection using the previously negotiated data.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;string.h&gt;
#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;gnutls/gnutls.h&gt;

/* Those functions are defined in other examples.
 */
extern void check_alert(gnutls_session_t session, int ret);
extern int tcp_connect(void);
extern void tcp_close(int sd);

#define MAX_BUF 1024
#define CAFILE &quot;/etc/ssl/certs/ca-certificates.crt&quot;
#define MSG &quot;GET / HTTP/1.0\r\n\r\n&quot;

int main(void)
{
        int ret;
        int sd, ii;
        gnutls_session_t session;
        char buffer[MAX_BUF + 1];
        gnutls_certificate_credentials_t xcred;

        /* variables used in session resuming 
         */
        int t;
        char *session_data = NULL;
        size_t session_data_size = 0;

        gnutls_global_init();

        /* X509 stuff */
        gnutls_certificate_allocate_credentials(&amp;xcred);

        gnutls_certificate_set_x509_trust_file(xcred, CAFILE,
                                               GNUTLS_X509_FMT_PEM);

        for (t = 0; t &lt; 2; t++) {       /* connect 2 times to the server */

                sd = tcp_connect();

                gnutls_init(&amp;session, GNUTLS_CLIENT);

                gnutls_priority_set_direct(session,
                                           &quot;PERFORMANCE:!ARCFOUR-128&quot;,
                                           NULL);

                gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE,
                                       xcred);

                if (t &gt; 0) {
                        /* if this is not the first time we connect */
                        gnutls_session_set_data(session, session_data,
                                                session_data_size);
                        free(session_data);
                }

                gnutls_transport_set_int(session, sd);
                gnutls_handshake_set_timeout(session,
                                             GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);

                /* Perform the TLS handshake
                 */
                do {
                        ret = gnutls_handshake(session);
                }
                while (ret &lt; 0 &amp;&amp; gnutls_error_is_fatal(ret) == 0);

                if (ret &lt; 0) {
                        fprintf(stderr, &quot;*** Handshake failed\n&quot;);
                        gnutls_perror(ret);
                        goto end;
                } else {
                        printf(&quot;- Handshake was completed\n&quot;);
                }

                if (t == 0) {   /* the first time we connect */
                        /* get the session data size */
                        gnutls_session_get_data(session, NULL,
                                                &amp;session_data_size);
                        session_data = malloc(session_data_size);

                        /* put session data to the session variable */
                        gnutls_session_get_data(session, session_data,
                                                &amp;session_data_size);

                } else {        /* the second time we connect */

                        /* check if we actually resumed the previous session */
                        if (gnutls_session_is_resumed(session) != 0) {
                                printf(&quot;- Previous session was resumed\n&quot;);
                        } else {
                                fprintf(stderr,
                                        &quot;*** Previous session was NOT resumed\n&quot;);
                        }
                }

                /* This function was defined in a previous example
                 */
                /* print_info(session); */

                gnutls_record_send(session, MSG, strlen(MSG));

                ret = gnutls_record_recv(session, buffer, MAX_BUF);
                if (ret == 0) {
                        printf(&quot;- Peer has closed the TLS connection\n&quot;);
                        goto end;
                } else if (ret &lt; 0 &amp;&amp; gnutls_error_is_fatal(ret) == 0) {
                        fprintf(stderr, &quot;*** Warning: %s\n&quot;,
                                gnutls_strerror(ret));
                } else if (ret &lt; 0) {
                        fprintf(stderr, &quot;*** Error: %s\n&quot;,
                                gnutls_strerror(ret));
                        goto end;
                }

                if (ret &gt; 0) {
                        printf(&quot;- Received %d bytes: &quot;, ret);
                        for (ii = 0; ii &lt; ret; ii++) {
                                fputc(buffer[ii], stdout);
                        }
                        fputs(&quot;\n&quot;, stdout);
                }

                gnutls_bye(session, GNUTLS_SHUT_RDWR);

              end:

                tcp_close(sd);

                gnutls_deinit(session);

        }                       /* for() */

        gnutls_certificate_free_credentials(xcred);

        gnutls_global_deinit();

        return 0;
}
</pre>

<hr>
<a name="Simple-client-example-with-SRP-authentication"></a>
<div class="header">
<p>
Next: <a href="#Simple-client-example-in-C_002b_002b" accesskey="n" rel="next">Simple client example in C++</a>, Previous: <a href="#Client-with-Resume-capability-example" accesskey="p" rel="prev">Client with Resume capability example</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Simple-client-example-with-SRP-authentication-1"></a>
<h4 class="subsection">7.1.10 Simple client example with <acronym>SRP</acronym> authentication</h4>

<p>The following client is a very simple <acronym>SRP</acronym> <acronym>TLS</acronym>
client which connects to a server and authenticates using a
<em>username</em> and a <em>password</em>. The server may authenticate
itself using a certificate, and in that case it has to be verified.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;gnutls/gnutls.h&gt;

/* Those functions are defined in other examples.
 */
extern void check_alert(gnutls_session_t session, int ret);
extern int tcp_connect(void);
extern void tcp_close(int sd);

#define MAX_BUF 1024
#define USERNAME &quot;user&quot;
#define PASSWORD &quot;pass&quot;
#define CAFILE &quot;/etc/ssl/certs/ca-certificates.crt&quot;
#define MSG &quot;GET / HTTP/1.0\r\n\r\n&quot;

int main(void)
{
        int ret;
        int sd, ii;
        gnutls_session_t session;
        char buffer[MAX_BUF + 1];
        gnutls_srp_client_credentials_t srp_cred;
        gnutls_certificate_credentials_t cert_cred;

        if (gnutls_check_version(&quot;3.1.4&quot;) == NULL) {
                fprintf(stderr, &quot;GnuTLS 3.1.4 or later is required for this example\n&quot;);
                exit(1);
        }

        /* for backwards compatibility with gnutls &lt; 3.3.0 */
        gnutls_global_init();

        gnutls_srp_allocate_client_credentials(&amp;srp_cred);
        gnutls_certificate_allocate_credentials(&amp;cert_cred);

        gnutls_certificate_set_x509_trust_file(cert_cred, CAFILE,
                                               GNUTLS_X509_FMT_PEM);
        gnutls_srp_set_client_credentials(srp_cred, USERNAME, PASSWORD);

        /* connects to server
         */
        sd = tcp_connect();

        /* Initialize TLS session
         */
        gnutls_init(&amp;session, GNUTLS_CLIENT);


        /* Set the priorities.
         */
        gnutls_priority_set_direct(session,
                                   &quot;NORMAL:+SRP:+SRP-RSA:+SRP-DSS&quot;,
                                   NULL);

        /* put the SRP credentials to the current session
         */
        gnutls_credentials_set(session, GNUTLS_CRD_SRP, srp_cred);
        gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, cert_cred);

        gnutls_transport_set_int(session, sd);
        gnutls_handshake_set_timeout(session,
                                     GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);

        /* Perform the TLS handshake
         */
        do {
                ret = gnutls_handshake(session);
        }
        while (ret &lt; 0 &amp;&amp; gnutls_error_is_fatal(ret) == 0);

        if (ret &lt; 0) {
                fprintf(stderr, &quot;*** Handshake failed\n&quot;);
                gnutls_perror(ret);
                goto end;
        } else {
                char *desc;

                desc = gnutls_session_get_desc(session);
                printf(&quot;- Session info: %s\n&quot;, desc);
                gnutls_free(desc);
        }

        gnutls_record_send(session, MSG, strlen(MSG));

        ret = gnutls_record_recv(session, buffer, MAX_BUF);
        if (gnutls_error_is_fatal(ret) != 0 || ret == 0) {
                if (ret == 0) {
                        printf
                            (&quot;- Peer has closed the GnuTLS connection\n&quot;);
                        goto end;
                } else {
                        fprintf(stderr, &quot;*** Error: %s\n&quot;,
                                gnutls_strerror(ret));
                        goto end;
                }
        } else
                check_alert(session, ret);

        if (ret &gt; 0) {
                printf(&quot;- Received %d bytes: &quot;, ret);
                for (ii = 0; ii &lt; ret; ii++) {
                        fputc(buffer[ii], stdout);
                }
                fputs(&quot;\n&quot;, stdout);
        }
        gnutls_bye(session, GNUTLS_SHUT_RDWR);

      end:

        tcp_close(sd);

        gnutls_deinit(session);

        gnutls_srp_free_client_credentials(srp_cred);
        gnutls_certificate_free_credentials(cert_cred);

        gnutls_global_deinit();

        return 0;
}
</pre>
<hr>
<a name="Simple-client-example-in-C_002b_002b"></a>
<div class="header">
<p>
Next: <a href="#Helper-functions-for-TCP-connections" accesskey="n" rel="next">Helper functions for TCP connections</a>, Previous: <a href="#Simple-client-example-with-SRP-authentication" accesskey="p" rel="prev">Simple client example with SRP authentication</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Simple-client-example-using-the-C_002b_002b-API"></a>
<h4 class="subsection">7.1.11 Simple client example using the C++ API</h4>

<p>The following client is a simple example of a client client utilizing
the GnuTLS C++ API.
</p>
<pre class="verbatim">#include &lt;config.h&gt;
#include &lt;iostream&gt;
#include &lt;stdexcept&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/gnutlsxx.h&gt;
#include &lt;cstring&gt; /* for strlen */

/* A very basic TLS client, with anonymous authentication.
 * written by Eduardo Villanueva Che.
 */

#define MAX_BUF 1024
#define SA struct sockaddr

#define CAFILE &quot;ca.pem&quot;
#define MSG &quot;GET / HTTP/1.0\r\n\r\n&quot;

extern &quot;C&quot;
{
    int tcp_connect(void);
    void tcp_close(int sd);
}


int main(void)
{
    int sd = -1;
    gnutls_global_init();

    try
    {

        /* Allow connections to servers that have OpenPGP keys as well.
         */
        gnutls::client_session session;

        /* X509 stuff */
        gnutls::certificate_credentials credentials;


        /* sets the trusted cas file
         */
        credentials.set_x509_trust_file(CAFILE, GNUTLS_X509_FMT_PEM);
        /* put the x509 credentials to the current session
         */
        session.set_credentials(credentials);

        /* Use default priorities */
        session.set_priority (&quot;NORMAL&quot;, NULL);

        /* connect to the peer
         */
        sd = tcp_connect();
        session.set_transport_ptr((gnutls_transport_ptr_t) (ptrdiff_t)sd);

        /* Perform the TLS handshake
         */
        int ret = session.handshake();
        if (ret &lt; 0)
        {
            throw std::runtime_error(&quot;Handshake failed&quot;);
        }
        else
        {
            std::cout &lt;&lt; &quot;- Handshake was completed&quot; &lt;&lt; std::endl;
        }

        session.send(MSG, strlen(MSG));
        char buffer[MAX_BUF + 1];
        ret = session.recv(buffer, MAX_BUF);
        if (ret == 0)
        {
            throw std::runtime_error(&quot;Peer has closed the TLS connection&quot;);
        }
        else if (ret &lt; 0)
        {
            throw std::runtime_error(gnutls_strerror(ret));
        }

        std::cout &lt;&lt; &quot;- Received &quot; &lt;&lt; ret &lt;&lt; &quot; bytes:&quot; &lt;&lt; std::endl;
        std::cout.write(buffer, ret);
        std::cout &lt;&lt; std::endl;

        session.bye(GNUTLS_SHUT_RDWR);
    }
    catch (std::exception &amp;ex)
    {
        std::cerr &lt;&lt; &quot;Exception caught: &quot; &lt;&lt; ex.what() &lt;&lt; std::endl;
    }

    if (sd != -1)
        tcp_close(sd);

    gnutls_global_deinit();

    return 0;
}
</pre>
<hr>
<a name="Helper-functions-for-TCP-connections"></a>
<div class="header">
<p>
Next: <a href="#Helper-functions-for-UDP-connections" accesskey="n" rel="next">Helper functions for UDP connections</a>, Previous: <a href="#Simple-client-example-in-C_002b_002b" accesskey="p" rel="prev">Simple client example in C++</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Helper-functions-for-TCP-connections-1"></a>
<h4 class="subsection">7.1.12 Helper functions for TCP connections</h4>

<p>Those helper function abstract away TCP connection handling from the
other examples.  It is required to build some examples.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;arpa/inet.h&gt;
#include &lt;netinet/in.h&gt;
#include &lt;unistd.h&gt;

/* tcp.c */
int tcp_connect(void);
void tcp_close(int sd);

/* Connects to the peer and returns a socket
 * descriptor.
 */
extern int tcp_connect(void)
{
        const char *PORT = &quot;5556&quot;;
        const char *SERVER = &quot;127.0.0.1&quot;;
        int err, sd;
        struct sockaddr_in sa;

        /* connects to server
         */
        sd = socket(AF_INET, SOCK_STREAM, 0);

        memset(&amp;sa, '\0', sizeof(sa));
        sa.sin_family = AF_INET;
        sa.sin_port = htons(atoi(PORT));
        inet_pton(AF_INET, SERVER, &amp;sa.sin_addr);

        err = connect(sd, (struct sockaddr *) &amp;sa, sizeof(sa));
        if (err &lt; 0) {
                fprintf(stderr, &quot;Connect error\n&quot;);
                exit(1);
        }

        return sd;
}

/* closes the given socket descriptor.
 */
extern void tcp_close(int sd)
{
        shutdown(sd, SHUT_RDWR);        /* no more receptions */
        close(sd);
}
</pre>
<hr>
<a name="Helper-functions-for-UDP-connections"></a>
<div class="header">
<p>
Previous: <a href="#Helper-functions-for-TCP-connections" accesskey="p" rel="prev">Helper functions for TCP connections</a>, Up: <a href="#Client-examples" accesskey="u" rel="up">Client examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Helper-functions-for-UDP-connections-1"></a>
<h4 class="subsection">7.1.13 Helper functions for UDP connections</h4>

<p>The UDP helper functions abstract away UDP connection handling from the
other examples.  It is required to build the examples using UDP.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;arpa/inet.h&gt;
#include &lt;netinet/in.h&gt;
#include &lt;unistd.h&gt;

/* udp.c */
int udp_connect(void);
void udp_close(int sd);

/* Connects to the peer and returns a socket
 * descriptor.
 */
extern int udp_connect(void)
{
        const char *PORT = &quot;5557&quot;;
        const char *SERVER = &quot;127.0.0.1&quot;;
        int err, sd, optval;
        struct sockaddr_in sa;

        /* connects to server
         */
        sd = socket(AF_INET, SOCK_DGRAM, 0);

        memset(&amp;sa, '\0', sizeof(sa));
        sa.sin_family = AF_INET;
        sa.sin_port = htons(atoi(PORT));
        inet_pton(AF_INET, SERVER, &amp;sa.sin_addr);

#if defined(IP_DONTFRAG)
        optval = 1;
        setsockopt(sd, IPPROTO_IP, IP_DONTFRAG,
                   (const void *) &amp;optval, sizeof(optval));
#elif defined(IP_MTU_DISCOVER)
        optval = IP_PMTUDISC_DO;
        setsockopt(sd, IPPROTO_IP, IP_MTU_DISCOVER,
                   (const void *) &amp;optval, sizeof(optval));
#endif

        err = connect(sd, (struct sockaddr *) &amp;sa, sizeof(sa));
        if (err &lt; 0) {
                fprintf(stderr, &quot;Connect error\n&quot;);
                exit(1);
        }

        return sd;
}

/* closes the given socket descriptor.
 */
extern void udp_close(int sd)
{
        close(sd);
}
</pre>
<hr>
<a name="Server-examples"></a>
<div class="header">
<p>
Next: <a href="#OCSP-example" accesskey="n" rel="next">OCSP example</a>, Previous: <a href="#Client-examples" accesskey="p" rel="prev">Client examples</a>, Up: <a href="#GnuTLS-application-examples" accesskey="u" rel="up">GnuTLS application examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Server-examples-1"></a>
<h3 class="section">7.2 Server examples</h3>

<p>This section contains examples of <acronym>TLS</acronym> and <acronym>SSL</acronym>
servers, using <acronym>GnuTLS</acronym>.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Echo-server-with-X_002e509-authentication" accesskey="1">Echo server with X.509 authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Echo-server-with-OpenPGP-authentication" accesskey="2">Echo server with OpenPGP authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Echo-server-with-SRP-authentication" accesskey="3">Echo server with SRP authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Echo-server-with-anonymous-authentication" accesskey="4">Echo server with anonymous authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#DTLS-echo-server-with-X_002e509-authentication" accesskey="5">DTLS echo server with X.509 authentication</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Echo-server-with-X_002e509-authentication"></a>
<div class="header">
<p>
Next: <a href="#Echo-server-with-OpenPGP-authentication" accesskey="n" rel="next">Echo server with OpenPGP authentication</a>, Up: <a href="#Server-examples" accesskey="u" rel="up">Server examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Echo-server-with-X_002e509-authentication-1"></a>
<h4 class="subsection">7.2.1 Echo server with <acronym>X.509</acronym> authentication</h4>

<p>This example is a very simple echo server which supports
<acronym>X.509</acronym> authentication.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;errno.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;arpa/inet.h&gt;
#include &lt;netinet/in.h&gt;
#include &lt;string.h&gt;
#include &lt;unistd.h&gt;
#include &lt;gnutls/gnutls.h&gt;

#define KEYFILE &quot;key.pem&quot;
#define CERTFILE &quot;cert.pem&quot;
#define CAFILE &quot;/etc/ssl/certs/ca-certificates.crt&quot;
#define CRLFILE &quot;crl.pem&quot;

/* The OCSP status file contains up to date information about revocation
 * of the server's certificate. That can be periodically be updated
 * using:
 * $ ocsptool --ask --load-cert your_cert.pem --load-issuer your_issuer.pem
 *            --load-signer your_issuer.pem --outfile ocsp-status.der
 */
#define OCSP_STATUS_FILE &quot;ocsp-status.der&quot;

/* This is a sample TLS 1.0 echo server, using X.509 authentication and
 * OCSP stapling support.
 */

#define MAX_BUF 1024
#define PORT 5556               /* listen to 5556 port */

/* These are global */
static gnutls_dh_params_t dh_params;

static int generate_dh_params(void)
{
        unsigned int bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH,
                                                        GNUTLS_SEC_PARAM_LEGACY);

        /* Generate Diffie-Hellman parameters - for use with DHE
         * kx algorithms. When short bit length is used, it might
         * be wise to regenerate parameters often.
         */
        gnutls_dh_params_init(&amp;dh_params);
        gnutls_dh_params_generate2(dh_params, bits);

        return 0;
}

int main(void)
{
        int listen_sd;
        int sd, ret;
        gnutls_certificate_credentials_t x509_cred;
        gnutls_priority_t priority_cache;
        struct sockaddr_in sa_serv;
        struct sockaddr_in sa_cli;
        socklen_t client_len;
        char topbuf[512];
        gnutls_session_t session;
        char buffer[MAX_BUF + 1];
        int optval = 1;

        /* for backwards compatibility with gnutls &lt; 3.3.0 */
        gnutls_global_init();

        gnutls_certificate_allocate_credentials(&amp;x509_cred);
        /* gnutls_certificate_set_x509_system_trust(xcred); */
        gnutls_certificate_set_x509_trust_file(x509_cred, CAFILE,
                                               GNUTLS_X509_FMT_PEM);

        gnutls_certificate_set_x509_crl_file(x509_cred, CRLFILE,
                                             GNUTLS_X509_FMT_PEM);

        ret =
            gnutls_certificate_set_x509_key_file(x509_cred, CERTFILE,
                                                 KEYFILE,
                                                 GNUTLS_X509_FMT_PEM);
        if (ret &lt; 0) {
                printf(&quot;No certificate or key were found\n&quot;);
                exit(1);
        }

        /* loads an OCSP status request if available */
        gnutls_certificate_set_ocsp_status_request_file(x509_cred,
                                                        OCSP_STATUS_FILE,
                                                        0);

        generate_dh_params();

        gnutls_priority_init(&amp;priority_cache,
                             &quot;PERFORMANCE:%SERVER_PRECEDENCE&quot;, NULL);


        gnutls_certificate_set_dh_params(x509_cred, dh_params);

        /* Socket operations
         */
        listen_sd = socket(AF_INET, SOCK_STREAM, 0);

        memset(&amp;sa_serv, '\0', sizeof(sa_serv));
        sa_serv.sin_family = AF_INET;
        sa_serv.sin_addr.s_addr = INADDR_ANY;
        sa_serv.sin_port = htons(PORT); /* Server Port number */

        setsockopt(listen_sd, SOL_SOCKET, SO_REUSEADDR, (void *) &amp;optval,
                   sizeof(int));

        bind(listen_sd, (struct sockaddr *) &amp;sa_serv, sizeof(sa_serv));

        listen(listen_sd, 1024);

        printf(&quot;Server ready. Listening to port '%d'.\n\n&quot;, PORT);

        client_len = sizeof(sa_cli);
        for (;;) {
                gnutls_init(&amp;session, GNUTLS_SERVER);
                gnutls_priority_set(session, priority_cache);
                gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE,
                                       x509_cred);

                /* We don't request any certificate from the client.
                 * If we did we would need to verify it. One way of
                 * doing that is shown in the &quot;Verifying a certificate&quot;
                 * example.
                 */
                gnutls_certificate_server_set_request(session,
                                                      GNUTLS_CERT_IGNORE);

                sd = accept(listen_sd, (struct sockaddr *) &amp;sa_cli,
                            &amp;client_len);

                printf(&quot;- connection from %s, port %d\n&quot;,
                       inet_ntop(AF_INET, &amp;sa_cli.sin_addr, topbuf,
                                 sizeof(topbuf)), ntohs(sa_cli.sin_port));

                gnutls_transport_set_int(session, sd);

                do {
                        ret = gnutls_handshake(session);
                }
                while (ret &lt; 0 &amp;&amp; gnutls_error_is_fatal(ret) == 0);

                if (ret &lt; 0) {
                        close(sd);
                        gnutls_deinit(session);
                        fprintf(stderr,
                                &quot;*** Handshake has failed (%s)\n\n&quot;,
                                gnutls_strerror(ret));
                        continue;
                }
                printf(&quot;- Handshake was completed\n&quot;);

                /* see the Getting peer's information example */
                /* print_info(session); */

                for (;;) {
                        ret = gnutls_record_recv(session, buffer, MAX_BUF);

                        if (ret == 0) {
                                printf
                                    (&quot;\n- Peer has closed the GnuTLS connection\n&quot;);
                                break;
                        } else if (ret &lt; 0
                                   &amp;&amp; gnutls_error_is_fatal(ret) == 0) {
                                fprintf(stderr, &quot;*** Warning: %s\n&quot;,
                                        gnutls_strerror(ret));
                        } else if (ret &lt; 0) {
                                fprintf(stderr, &quot;\n*** Received corrupted &quot;
                                        &quot;data(%d). Closing the connection.\n\n&quot;,
                                        ret);
                                break;
                        } else if (ret &gt; 0) {
                                /* echo data back to the client
                                 */
                                gnutls_record_send(session, buffer, ret);
                        }
                }
                printf(&quot;\n&quot;);
                /* do not wait for the peer to close the connection.
                 */
                gnutls_bye(session, GNUTLS_SHUT_WR);

                close(sd);
                gnutls_deinit(session);

        }
        close(listen_sd);

        gnutls_certificate_free_credentials(x509_cred);
        gnutls_priority_deinit(priority_cache);

        gnutls_global_deinit();

        return 0;

}
</pre>
<hr>
<a name="Echo-server-with-OpenPGP-authentication"></a>
<div class="header">
<p>
Next: <a href="#Echo-server-with-SRP-authentication" accesskey="n" rel="next">Echo server with SRP authentication</a>, Previous: <a href="#Echo-server-with-X_002e509-authentication" accesskey="p" rel="prev">Echo server with X.509 authentication</a>, Up: <a href="#Server-examples" accesskey="u" rel="up">Server examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Echo-server-with-OpenPGP-authentication-1"></a>
<h4 class="subsection">7.2.2 Echo server with <acronym>OpenPGP</acronym> authentication</h4>
<a name="index-OpenPGP-server"></a>

<p>The following example is an echo server which supports
<acronym>OpenPGP</acronym> key authentication. You can easily combine
this functionality &mdash;that is have a server that supports both
<acronym>X.509</acronym> and <acronym>OpenPGP</acronym> certificates&mdash; but we separated
them to keep these examples as simple as possible.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;errno.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;arpa/inet.h&gt;
#include &lt;netinet/in.h&gt;
#include &lt;string.h&gt;
#include &lt;unistd.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/openpgp.h&gt;

#define KEYFILE &quot;secret.asc&quot;
#define CERTFILE &quot;public.asc&quot;
#define RINGFILE &quot;ring.gpg&quot;

/* This is a sample TLS 1.0-OpenPGP echo server.
 */


#define SOCKET_ERR(err,s) if(err==-1) {perror(s);return(1);}
#define MAX_BUF 1024
#define PORT 5556               /* listen to 5556 port */

/* These are global */
gnutls_dh_params_t dh_params;

static int generate_dh_params(void)
{
        unsigned int bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH,
                                                        GNUTLS_SEC_PARAM_LEGACY);

        /* Generate Diffie-Hellman parameters - for use with DHE
         * kx algorithms. These should be discarded and regenerated
         * once a day, once a week or once a month. Depending on the
         * security requirements.
         */
        gnutls_dh_params_init(&amp;dh_params);
        gnutls_dh_params_generate2(dh_params, bits);

        return 0;
}

int main(void)
{
        int err, listen_sd;
        int sd, ret;
        struct sockaddr_in sa_serv;
        struct sockaddr_in sa_cli;
        socklen_t client_len;
        char topbuf[512];
        gnutls_session_t session;
        gnutls_certificate_credentials_t cred;
        char buffer[MAX_BUF + 1];
        int optval = 1;
        char name[256];

        strcpy(name, &quot;Echo Server&quot;);

        if (gnutls_check_version(&quot;3.1.4&quot;) == NULL) {
                fprintf(stderr, &quot;GnuTLS 3.1.4 or later is required for this example\n&quot;);
                exit(1);
        }

        /* for backwards compatibility with gnutls &lt; 3.3.0 */
        gnutls_global_init();

        gnutls_certificate_allocate_credentials(&amp;cred);
        gnutls_certificate_set_openpgp_keyring_file(cred, RINGFILE,
                                                    GNUTLS_OPENPGP_FMT_BASE64);

        gnutls_certificate_set_openpgp_key_file(cred, CERTFILE, KEYFILE,
                                                GNUTLS_OPENPGP_FMT_BASE64);

        generate_dh_params();

        gnutls_certificate_set_dh_params(cred, dh_params);

        /* Socket operations
         */
        listen_sd = socket(AF_INET, SOCK_STREAM, 0);
        SOCKET_ERR(listen_sd, &quot;socket&quot;);

        memset(&amp;sa_serv, '\0', sizeof(sa_serv));
        sa_serv.sin_family = AF_INET;
        sa_serv.sin_addr.s_addr = INADDR_ANY;
        sa_serv.sin_port = htons(PORT); /* Server Port number */

        setsockopt(listen_sd, SOL_SOCKET, SO_REUSEADDR, (void *) &amp;optval,
                   sizeof(int));

        err =
            bind(listen_sd, (struct sockaddr *) &amp;sa_serv, sizeof(sa_serv));
        SOCKET_ERR(err, &quot;bind&quot;);
        err = listen(listen_sd, 1024);
        SOCKET_ERR(err, &quot;listen&quot;);

        printf(&quot;%s ready. Listening to port '%d'.\n\n&quot;, name, PORT);

        client_len = sizeof(sa_cli);
        for (;;) {
                gnutls_init(&amp;session, GNUTLS_SERVER);
                gnutls_priority_set_direct(session,
                                           &quot;NORMAL:+CTYPE-OPENPGP&quot;, NULL);

                /* request client certificate if any.
                 */
                gnutls_certificate_server_set_request(session,
                                                      GNUTLS_CERT_REQUEST);

                sd = accept(listen_sd, (struct sockaddr *) &amp;sa_cli,
                            &amp;client_len);

                printf(&quot;- connection from %s, port %d\n&quot;,
                       inet_ntop(AF_INET, &amp;sa_cli.sin_addr, topbuf,
                                 sizeof(topbuf)), ntohs(sa_cli.sin_port));

                gnutls_transport_set_int(session, sd);
                ret = gnutls_handshake(session);
                if (ret &lt; 0) {
                        close(sd);
                        gnutls_deinit(session);
                        fprintf(stderr,
                                &quot;*** Handshake has failed (%s)\n\n&quot;,
                                gnutls_strerror(ret));
                        continue;
                }
                printf(&quot;- Handshake was completed\n&quot;);

                /* see the Getting peer's information example */
                /* print_info(session); */

                for (;;) {
                        ret = gnutls_record_recv(session, buffer, MAX_BUF);

                        if (ret == 0) {
                                printf
                                    (&quot;\n- Peer has closed the GnuTLS connection\n&quot;);
                                break;
                        } else if (ret &lt; 0
                                   &amp;&amp; gnutls_error_is_fatal(ret) == 0) {
                                fprintf(stderr, &quot;*** Warning: %s\n&quot;,
                                        gnutls_strerror(ret));
                        } else if (ret &lt; 0) {
                                fprintf(stderr, &quot;\n*** Received corrupted &quot;
                                        &quot;data(%d). Closing the connection.\n\n&quot;,
                                        ret);
                                break;
                        } else if (ret &gt; 0) {
                                /* echo data back to the client
                                 */
                                gnutls_record_send(session, buffer, ret);
                        }
                }
                printf(&quot;\n&quot;);
                /* do not wait for the peer to close the connection.
                 */
                gnutls_bye(session, GNUTLS_SHUT_WR);

                close(sd);
                gnutls_deinit(session);

        }
        close(listen_sd);

        gnutls_certificate_free_credentials(cred);

        gnutls_global_deinit();

        return 0;

}
</pre>
<hr>
<a name="Echo-server-with-SRP-authentication"></a>
<div class="header">
<p>
Next: <a href="#Echo-server-with-anonymous-authentication" accesskey="n" rel="next">Echo server with anonymous authentication</a>, Previous: <a href="#Echo-server-with-OpenPGP-authentication" accesskey="p" rel="prev">Echo server with OpenPGP authentication</a>, Up: <a href="#Server-examples" accesskey="u" rel="up">Server examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Echo-server-with-SRP-authentication-1"></a>
<h4 class="subsection">7.2.3 Echo server with <acronym>SRP</acronym> authentication</h4>

<p>This is a server which supports <acronym>SRP</acronym> authentication. It is
also possible to combine this functionality with a certificate
server. Here it is separate for simplicity.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;errno.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;arpa/inet.h&gt;
#include &lt;netinet/in.h&gt;
#include &lt;string.h&gt;
#include &lt;unistd.h&gt;
#include &lt;gnutls/gnutls.h&gt;

#define SRP_PASSWD &quot;tpasswd&quot;
#define SRP_PASSWD_CONF &quot;tpasswd.conf&quot;

#define KEYFILE &quot;key.pem&quot;
#define CERTFILE &quot;cert.pem&quot;
#define CAFILE &quot;/etc/ssl/certs/ca-certificates.crt&quot;

/* This is a sample TLS-SRP echo server.
 */

#define SOCKET_ERR(err,s) if(err==-1) {perror(s);return(1);}
#define MAX_BUF 1024
#define PORT 5556               /* listen to 5556 port */

int main(void)
{
        int err, listen_sd;
        int sd, ret;
        struct sockaddr_in sa_serv;
        struct sockaddr_in sa_cli;
        socklen_t client_len;
        char topbuf[512];
        gnutls_session_t session;
        gnutls_srp_server_credentials_t srp_cred;
        gnutls_certificate_credentials_t cert_cred;
        char buffer[MAX_BUF + 1];
        int optval = 1;
        char name[256];

        strcpy(name, &quot;Echo Server&quot;);

        if (gnutls_check_version(&quot;3.1.4&quot;) == NULL) {
                fprintf(stderr, &quot;GnuTLS 3.1.4 or later is required for this example\n&quot;);
                exit(1);
        }

        /* for backwards compatibility with gnutls &lt; 3.3.0 */
        gnutls_global_init();

        /* SRP_PASSWD a password file (created with the included srptool utility) 
         */
        gnutls_srp_allocate_server_credentials(&amp;srp_cred);
        gnutls_srp_set_server_credentials_file(srp_cred, SRP_PASSWD,
                                               SRP_PASSWD_CONF);

        gnutls_certificate_allocate_credentials(&amp;cert_cred);
        gnutls_certificate_set_x509_trust_file(cert_cred, CAFILE,
                                               GNUTLS_X509_FMT_PEM);
        gnutls_certificate_set_x509_key_file(cert_cred, CERTFILE, KEYFILE,
                                             GNUTLS_X509_FMT_PEM);

        /* TCP socket operations
         */
        listen_sd = socket(AF_INET, SOCK_STREAM, 0);
        SOCKET_ERR(listen_sd, &quot;socket&quot;);

        memset(&amp;sa_serv, '\0', sizeof(sa_serv));
        sa_serv.sin_family = AF_INET;
        sa_serv.sin_addr.s_addr = INADDR_ANY;
        sa_serv.sin_port = htons(PORT); /* Server Port number */

        setsockopt(listen_sd, SOL_SOCKET, SO_REUSEADDR, (void *) &amp;optval,
                   sizeof(int));

        err =
            bind(listen_sd, (struct sockaddr *) &amp;sa_serv, sizeof(sa_serv));
        SOCKET_ERR(err, &quot;bind&quot;);
        err = listen(listen_sd, 1024);
        SOCKET_ERR(err, &quot;listen&quot;);

        printf(&quot;%s ready. Listening to port '%d'.\n\n&quot;, name, PORT);

        client_len = sizeof(sa_cli);
        for (;;) {
                gnutls_init(&amp;session, GNUTLS_SERVER);
                gnutls_priority_set_direct(session,
                                           &quot;NORMAL&quot;
                                           &quot;:-KX-ALL:+SRP:+SRP-DSS:+SRP-RSA&quot;,
                                           NULL);
                gnutls_credentials_set(session, GNUTLS_CRD_SRP, srp_cred);
                /* for the certificate authenticated ciphersuites.
                 */
                gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE,
                                       cert_cred);

                /* We don't request any certificate from the client.
                 * If we did we would need to verify it. One way of
                 * doing that is shown in the &quot;Verifying a certificate&quot;
                 * example.
                 */
                gnutls_certificate_server_set_request(session,
                                                      GNUTLS_CERT_IGNORE);

                sd = accept(listen_sd, (struct sockaddr *) &amp;sa_cli,
                            &amp;client_len);

                printf(&quot;- connection from %s, port %d\n&quot;,
                       inet_ntop(AF_INET, &amp;sa_cli.sin_addr, topbuf,
                                 sizeof(topbuf)), ntohs(sa_cli.sin_port));

                gnutls_transport_set_int(session, sd);

                do {
                        ret = gnutls_handshake(session);
                }
                while (ret &lt; 0 &amp;&amp; gnutls_error_is_fatal(ret) == 0);

                if (ret &lt; 0) {
                        close(sd);
                        gnutls_deinit(session);
                        fprintf(stderr,
                                &quot;*** Handshake has failed (%s)\n\n&quot;,
                                gnutls_strerror(ret));
                        continue;
                }
                printf(&quot;- Handshake was completed\n&quot;);
                printf(&quot;- User %s was connected\n&quot;,
                       gnutls_srp_server_get_username(session));

                /* print_info(session); */

                for (;;) {
                        ret = gnutls_record_recv(session, buffer, MAX_BUF);

                        if (ret == 0) {
                                printf
                                    (&quot;\n- Peer has closed the GnuTLS connection\n&quot;);
                                break;
                        } else if (ret &lt; 0
                                   &amp;&amp; gnutls_error_is_fatal(ret) == 0) {
                                fprintf(stderr, &quot;*** Warning: %s\n&quot;,
                                        gnutls_strerror(ret));
                        } else if (ret &lt; 0) {
                                fprintf(stderr, &quot;\n*** Received corrupted &quot;
                                        &quot;data(%d). Closing the connection.\n\n&quot;,
                                        ret);
                                break;
                        } else if (ret &gt; 0) {
                                /* echo data back to the client
                                 */
                                gnutls_record_send(session, buffer, ret);
                        }
                }
                printf(&quot;\n&quot;);
                /* do not wait for the peer to close the connection. */
                gnutls_bye(session, GNUTLS_SHUT_WR);

                close(sd);
                gnutls_deinit(session);

        }
        close(listen_sd);

        gnutls_srp_free_server_credentials(srp_cred);
        gnutls_certificate_free_credentials(cert_cred);

        gnutls_global_deinit();

        return 0;

}
</pre>
<hr>
<a name="Echo-server-with-anonymous-authentication"></a>
<div class="header">
<p>
Next: <a href="#DTLS-echo-server-with-X_002e509-authentication" accesskey="n" rel="next">DTLS echo server with X.509 authentication</a>, Previous: <a href="#Echo-server-with-SRP-authentication" accesskey="p" rel="prev">Echo server with SRP authentication</a>, Up: <a href="#Server-examples" accesskey="u" rel="up">Server examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Echo-server-with-anonymous-authentication-1"></a>
<h4 class="subsection">7.2.4 Echo server with anonymous authentication</h4>

<p>This example server supports anonymous authentication, and could be
used to serve the example client for anonymous authentication.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;errno.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;arpa/inet.h&gt;
#include &lt;netinet/in.h&gt;
#include &lt;string.h&gt;
#include &lt;unistd.h&gt;
#include &lt;gnutls/gnutls.h&gt;

/* This is a sample TLS 1.0 echo server, for anonymous authentication only.
 */


#define SOCKET_ERR(err,s) if(err==-1) {perror(s);return(1);}
#define MAX_BUF 1024
#define PORT 5556               /* listen to 5556 port */

/* These are global */
static gnutls_dh_params_t dh_params;

static int generate_dh_params(void)
{
        unsigned int bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH,
                                                        GNUTLS_SEC_PARAM_LEGACY);
        /* Generate Diffie-Hellman parameters - for use with DHE
         * kx algorithms. These should be discarded and regenerated
         * once a day, once a week or once a month. Depending on the
         * security requirements.
         */
        gnutls_dh_params_init(&amp;dh_params);
        gnutls_dh_params_generate2(dh_params, bits);

        return 0;
}

int main(void)
{
        int err, listen_sd;
        int sd, ret;
        struct sockaddr_in sa_serv;
        struct sockaddr_in sa_cli;
        socklen_t client_len;
        char topbuf[512];
        gnutls_session_t session;
        gnutls_anon_server_credentials_t anoncred;
        char buffer[MAX_BUF + 1];
        int optval = 1;

        if (gnutls_check_version(&quot;3.1.4&quot;) == NULL) {
                fprintf(stderr, &quot;GnuTLS 3.1.4 or later is required for this example\n&quot;);
                exit(1);
        }

        /* for backwards compatibility with gnutls &lt; 3.3.0 */
        gnutls_global_init();

        gnutls_anon_allocate_server_credentials(&amp;anoncred);

        generate_dh_params();

        gnutls_anon_set_server_dh_params(anoncred, dh_params);

        /* Socket operations
         */
        listen_sd = socket(AF_INET, SOCK_STREAM, 0);
        SOCKET_ERR(listen_sd, &quot;socket&quot;);

        memset(&amp;sa_serv, '\0', sizeof(sa_serv));
        sa_serv.sin_family = AF_INET;
        sa_serv.sin_addr.s_addr = INADDR_ANY;
        sa_serv.sin_port = htons(PORT); /* Server Port number */

        setsockopt(listen_sd, SOL_SOCKET, SO_REUSEADDR, (void *) &amp;optval,
                   sizeof(int));

        err =
            bind(listen_sd, (struct sockaddr *) &amp;sa_serv, sizeof(sa_serv));
        SOCKET_ERR(err, &quot;bind&quot;);
        err = listen(listen_sd, 1024);
        SOCKET_ERR(err, &quot;listen&quot;);

        printf(&quot;Server ready. Listening to port '%d'.\n\n&quot;, PORT);

        client_len = sizeof(sa_cli);
        for (;;) {
                gnutls_init(&amp;session, GNUTLS_SERVER);
                gnutls_priority_set_direct(session,
                                           &quot;NORMAL:+ANON-ECDH:+ANON-DH&quot;,
                                           NULL);
                gnutls_credentials_set(session, GNUTLS_CRD_ANON, anoncred);

                sd = accept(listen_sd, (struct sockaddr *) &amp;sa_cli,
                            &amp;client_len);

                printf(&quot;- connection from %s, port %d\n&quot;,
                       inet_ntop(AF_INET, &amp;sa_cli.sin_addr, topbuf,
                                 sizeof(topbuf)), ntohs(sa_cli.sin_port));

                gnutls_transport_set_int(session, sd);

                do {
                        ret = gnutls_handshake(session);
                }
                while (ret &lt; 0 &amp;&amp; gnutls_error_is_fatal(ret) == 0);

                if (ret &lt; 0) {
                        close(sd);
                        gnutls_deinit(session);
                        fprintf(stderr,
                                &quot;*** Handshake has failed (%s)\n\n&quot;,
                                gnutls_strerror(ret));
                        continue;
                }
                printf(&quot;- Handshake was completed\n&quot;);

                /* see the Getting peer's information example */
                /* print_info(session); */

                for (;;) {
                        ret = gnutls_record_recv(session, buffer, MAX_BUF);

                        if (ret == 0) {
                                printf
                                    (&quot;\n- Peer has closed the GnuTLS connection\n&quot;);
                                break;
                        } else if (ret &lt; 0
                                   &amp;&amp; gnutls_error_is_fatal(ret) == 0) {
                                fprintf(stderr, &quot;*** Warning: %s\n&quot;,
                                        gnutls_strerror(ret));
                        } else if (ret &lt; 0) {
                                fprintf(stderr, &quot;\n*** Received corrupted &quot;
                                        &quot;data(%d). Closing the connection.\n\n&quot;,
                                        ret);
                                break;
                        } else if (ret &gt; 0) {
                                /* echo data back to the client
                                 */
                                gnutls_record_send(session, buffer, ret);
                        }
                }
                printf(&quot;\n&quot;);
                /* do not wait for the peer to close the connection.
                 */
                gnutls_bye(session, GNUTLS_SHUT_WR);

                close(sd);
                gnutls_deinit(session);

        }
        close(listen_sd);

        gnutls_anon_free_server_credentials(anoncred);

        gnutls_global_deinit();

        return 0;

}
</pre>
<hr>
<a name="DTLS-echo-server-with-X_002e509-authentication"></a>
<div class="header">
<p>
Previous: <a href="#Echo-server-with-anonymous-authentication" accesskey="p" rel="prev">Echo server with anonymous authentication</a>, Up: <a href="#Server-examples" accesskey="u" rel="up">Server examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="DTLS-echo-server-with-X_002e509-authentication-1"></a>
<h4 class="subsection">7.2.5 DTLS echo server with <acronym>X.509</acronym> authentication</h4>

<p>This example is a very simple echo server using Datagram TLS and 
<acronym>X.509</acronym> authentication.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;errno.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/socket.h&gt;
#include &lt;arpa/inet.h&gt;
#include &lt;netinet/in.h&gt;
#include &lt;sys/select.h&gt;
#include &lt;netdb.h&gt;
#include &lt;string.h&gt;
#include &lt;unistd.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/dtls.h&gt;

#define KEYFILE &quot;key.pem&quot;
#define CERTFILE &quot;cert.pem&quot;
#define CAFILE &quot;/etc/ssl/certs/ca-certificates.crt&quot;
#define CRLFILE &quot;crl.pem&quot;

/* This is a sample DTLS echo server, using X.509 authentication.
 * Note that error checking is minimal to simplify the example.
 */

#define MAX_BUFFER 1024
#define PORT 5557

typedef struct {
        gnutls_session_t session;
        int fd;
        struct sockaddr *cli_addr;
        socklen_t cli_addr_size;
} priv_data_st;

static int pull_timeout_func(gnutls_transport_ptr_t ptr, unsigned int ms);
static ssize_t push_func(gnutls_transport_ptr_t p, const void *data,
                         size_t size);
static ssize_t pull_func(gnutls_transport_ptr_t p, void *data,
                         size_t size);
static const char *human_addr(const struct sockaddr *sa, socklen_t salen,
                              char *buf, size_t buflen);
static int wait_for_connection(int fd);
static int generate_dh_params(void);

/* Use global credentials and parameters to simplify
 * the example. */
static gnutls_certificate_credentials_t x509_cred;
static gnutls_priority_t priority_cache;
static gnutls_dh_params_t dh_params;

int main(void)
{
        int listen_sd;
        int sock, ret;
        struct sockaddr_in sa_serv;
        struct sockaddr_in cli_addr;
        socklen_t cli_addr_size;
        gnutls_session_t session;
        char buffer[MAX_BUFFER];
        priv_data_st priv;
        gnutls_datum_t cookie_key;
        gnutls_dtls_prestate_st prestate;
        int mtu = 1400;
        unsigned char sequence[8];

        /* this must be called once in the program
         */
        gnutls_global_init();

        gnutls_certificate_allocate_credentials(&amp;x509_cred);
        gnutls_certificate_set_x509_trust_file(x509_cred, CAFILE,
                                               GNUTLS_X509_FMT_PEM);

        gnutls_certificate_set_x509_crl_file(x509_cred, CRLFILE,
                                             GNUTLS_X509_FMT_PEM);

        ret =
            gnutls_certificate_set_x509_key_file(x509_cred, CERTFILE,
                                                 KEYFILE,
                                                 GNUTLS_X509_FMT_PEM);
        if (ret &lt; 0) {
                printf(&quot;No certificate or key were found\n&quot;);
                exit(1);
        }

        generate_dh_params();

        gnutls_certificate_set_dh_params(x509_cred, dh_params);

        gnutls_priority_init(&amp;priority_cache,
                             &quot;PERFORMANCE:-VERS-TLS-ALL:+VERS-DTLS1.0:%SERVER_PRECEDENCE&quot;,
                             NULL);

        gnutls_key_generate(&amp;cookie_key, GNUTLS_COOKIE_KEY_SIZE);

        /* Socket operations
         */
        listen_sd = socket(AF_INET, SOCK_DGRAM, 0);

        memset(&amp;sa_serv, '\0', sizeof(sa_serv));
        sa_serv.sin_family = AF_INET;
        sa_serv.sin_addr.s_addr = INADDR_ANY;
        sa_serv.sin_port = htons(PORT);

        {                       /* DTLS requires the IP don't fragment (DF) bit to be set */
#if defined(IP_DONTFRAG)
                int optval = 1;
                setsockopt(listen_sd, IPPROTO_IP, IP_DONTFRAG,
                           (const void *) &amp;optval, sizeof(optval));
#elif defined(IP_MTU_DISCOVER)
                int optval = IP_PMTUDISC_DO;
                setsockopt(listen_sd, IPPROTO_IP, IP_MTU_DISCOVER,
                           (const void *) &amp;optval, sizeof(optval));
#endif
        }

        bind(listen_sd, (struct sockaddr *) &amp;sa_serv, sizeof(sa_serv));

        printf(&quot;UDP server ready. Listening to port '%d'.\n\n&quot;, PORT);

        for (;;) {
                printf(&quot;Waiting for connection...\n&quot;);
                sock = wait_for_connection(listen_sd);
                if (sock &lt; 0)
                        continue;

                cli_addr_size = sizeof(cli_addr);
                ret = recvfrom(sock, buffer, sizeof(buffer), MSG_PEEK,
                               (struct sockaddr *) &amp;cli_addr,
                               &amp;cli_addr_size);
                if (ret &gt; 0) {
                        memset(&amp;prestate, 0, sizeof(prestate));
                        ret =
                            gnutls_dtls_cookie_verify(&amp;cookie_key,
                                                      &amp;cli_addr,
                                                      sizeof(cli_addr),
                                                      buffer, ret,
                                                      &amp;prestate);
                        if (ret &lt; 0) {  /* cookie not valid */
                                priv_data_st s;

                                memset(&amp;s, 0, sizeof(s));
                                s.fd = sock;
                                s.cli_addr = (void *) &amp;cli_addr;
                                s.cli_addr_size = sizeof(cli_addr);

                                printf
                                    (&quot;Sending hello verify request to %s\n&quot;,
                                     human_addr((struct sockaddr *)
                                                &amp;cli_addr,
                                                sizeof(cli_addr), buffer,
                                                sizeof(buffer)));

                                gnutls_dtls_cookie_send(&amp;cookie_key,
                                                        &amp;cli_addr,
                                                        sizeof(cli_addr),
                                                        &amp;prestate,
                                                        (gnutls_transport_ptr_t)
                                                        &amp; s, push_func);

                                /* discard peeked data */
                                recvfrom(sock, buffer, sizeof(buffer), 0,
                                         (struct sockaddr *) &amp;cli_addr,
                                         &amp;cli_addr_size);
                                usleep(100);
                                continue;
                        }
                        printf(&quot;Accepted connection from %s\n&quot;,
                               human_addr((struct sockaddr *)
                                          &amp;cli_addr, sizeof(cli_addr),
                                          buffer, sizeof(buffer)));
                } else
                        continue;

                gnutls_init(&amp;session, GNUTLS_SERVER | GNUTLS_DATAGRAM);
                gnutls_priority_set(session, priority_cache);
                gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE,
                                       x509_cred);

                gnutls_dtls_prestate_set(session, &amp;prestate);
                gnutls_dtls_set_mtu(session, mtu);

                priv.session = session;
                priv.fd = sock;
                priv.cli_addr = (struct sockaddr *) &amp;cli_addr;
                priv.cli_addr_size = sizeof(cli_addr);

                gnutls_transport_set_ptr(session, &amp;priv);
                gnutls_transport_set_push_function(session, push_func);
                gnutls_transport_set_pull_function(session, pull_func);
                gnutls_transport_set_pull_timeout_function(session,
                                                           pull_timeout_func);

                do {
                        ret = gnutls_handshake(session);
                }
                while (ret == GNUTLS_E_INTERRUPTED
                       || ret == GNUTLS_E_AGAIN);
                /* Note that DTLS may also receive GNUTLS_E_LARGE_PACKET.
                 * In that case the MTU should be adjusted.
                 */

                if (ret &lt; 0) {
                        fprintf(stderr, &quot;Error in handshake(): %s\n&quot;,
                                gnutls_strerror(ret));
                        gnutls_deinit(session);
                        continue;
                }

                printf(&quot;- Handshake was completed\n&quot;);

                for (;;) {
                        do {
                                ret =
                                    gnutls_record_recv_seq(session, buffer,
                                                           MAX_BUFFER,
                                                           sequence);
                        }
                        while (ret == GNUTLS_E_AGAIN
                               || ret == GNUTLS_E_INTERRUPTED);

                        if (ret &lt; 0 &amp;&amp; gnutls_error_is_fatal(ret) == 0) {
                                fprintf(stderr, &quot;*** Warning: %s\n&quot;,
                                        gnutls_strerror(ret));
                                continue;
                        } else if (ret &lt; 0) {
                                fprintf(stderr, &quot;Error in recv(): %s\n&quot;,
                                        gnutls_strerror(ret));
                                break;
                        }

                        if (ret == 0) {
                                printf(&quot;EOF\n\n&quot;);
                                break;
                        }

                        buffer[ret] = 0;
                        printf
                            (&quot;received[%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x]: %s\n&quot;,
                             sequence[0], sequence[1], sequence[2],
                             sequence[3], sequence[4], sequence[5],
                             sequence[6], sequence[7], buffer);

                        /* reply back */
                        ret = gnutls_record_send(session, buffer, ret);
                        if (ret &lt; 0) {
                                fprintf(stderr, &quot;Error in send(): %s\n&quot;,
                                        gnutls_strerror(ret));
                                break;
                        }
                }

                gnutls_bye(session, GNUTLS_SHUT_WR);
                gnutls_deinit(session);

        }
        close(listen_sd);

        gnutls_certificate_free_credentials(x509_cred);
        gnutls_priority_deinit(priority_cache);

        gnutls_global_deinit();

        return 0;

}

static int wait_for_connection(int fd)
{
        fd_set rd, wr;
        int n;

        FD_ZERO(&amp;rd);
        FD_ZERO(&amp;wr);

        FD_SET(fd, &amp;rd);

        /* waiting part */
        n = select(fd + 1, &amp;rd, &amp;wr, NULL, NULL);
        if (n == -1 &amp;&amp; errno == EINTR)
                return -1;
        if (n &lt; 0) {
                perror(&quot;select()&quot;);
                exit(1);
        }

        return fd;
}

/* Wait for data to be received within a timeout period in milliseconds
 */
static int pull_timeout_func(gnutls_transport_ptr_t ptr, unsigned int ms)
{
        fd_set rfds;
        struct timeval tv;
        priv_data_st *priv = ptr;
        struct sockaddr_in cli_addr;
        socklen_t cli_addr_size;
        int ret;
        char c;

        FD_ZERO(&amp;rfds);
        FD_SET(priv-&gt;fd, &amp;rfds);

        tv.tv_sec = 0;
        tv.tv_usec = ms * 1000;

        while (tv.tv_usec &gt;= 1000000) {
                tv.tv_usec -= 1000000;
                tv.tv_sec++;
        }

        ret = select(priv-&gt;fd + 1, &amp;rfds, NULL, NULL, &amp;tv);

        if (ret &lt;= 0)
                return ret;

        /* only report ok if the next message is from the peer we expect
         * from 
         */
        cli_addr_size = sizeof(cli_addr);
        ret =
            recvfrom(priv-&gt;fd, &amp;c, 1, MSG_PEEK,
                     (struct sockaddr *) &amp;cli_addr, &amp;cli_addr_size);
        if (ret &gt; 0) {
                if (cli_addr_size == priv-&gt;cli_addr_size
                    &amp;&amp; memcmp(&amp;cli_addr, priv-&gt;cli_addr,
                              sizeof(cli_addr)) == 0)
                        return 1;
        }

        return 0;
}

static ssize_t
push_func(gnutls_transport_ptr_t p, const void *data, size_t size)
{
        priv_data_st *priv = p;

        return sendto(priv-&gt;fd, data, size, 0, priv-&gt;cli_addr,
                      priv-&gt;cli_addr_size);
}

static ssize_t pull_func(gnutls_transport_ptr_t p, void *data, size_t size)
{
        priv_data_st *priv = p;
        struct sockaddr_in cli_addr;
        socklen_t cli_addr_size;
        char buffer[64];
        int ret;

        cli_addr_size = sizeof(cli_addr);
        ret =
            recvfrom(priv-&gt;fd, data, size, 0,
                     (struct sockaddr *) &amp;cli_addr, &amp;cli_addr_size);
        if (ret == -1)
                return ret;

        if (cli_addr_size == priv-&gt;cli_addr_size
            &amp;&amp; memcmp(&amp;cli_addr, priv-&gt;cli_addr, sizeof(cli_addr)) == 0)
                return ret;

        printf(&quot;Denied connection from %s\n&quot;,
               human_addr((struct sockaddr *)
                          &amp;cli_addr, sizeof(cli_addr), buffer,
                          sizeof(buffer)));

        gnutls_transport_set_errno(priv-&gt;session, EAGAIN);
        return -1;
}

static const char *human_addr(const struct sockaddr *sa, socklen_t salen,
                              char *buf, size_t buflen)
{
        const char *save_buf = buf;
        size_t l;

        if (!buf || !buflen)
                return NULL;

        *buf = '\0';

        switch (sa-&gt;sa_family) {
#if HAVE_IPV6
        case AF_INET6:
                snprintf(buf, buflen, &quot;IPv6 &quot;);
                break;
#endif

        case AF_INET:
                snprintf(buf, buflen, &quot;IPv4 &quot;);
                break;
        }

        l = strlen(buf);
        buf += l;
        buflen -= l;

        if (getnameinfo(sa, salen, buf, buflen, NULL, 0, NI_NUMERICHOST) !=
            0)
                return NULL;

        l = strlen(buf);
        buf += l;
        buflen -= l;

        strncat(buf, &quot; port &quot;, buflen);

        l = strlen(buf);
        buf += l;
        buflen -= l;

        if (getnameinfo(sa, salen, NULL, 0, buf, buflen, NI_NUMERICSERV) !=
            0)
                return NULL;

        return save_buf;
}

static int generate_dh_params(void)
{
        int bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH,
                                               GNUTLS_SEC_PARAM_LEGACY);

        /* Generate Diffie-Hellman parameters - for use with DHE
         * kx algorithms. When short bit length is used, it might
         * be wise to regenerate parameters often.
         */
        gnutls_dh_params_init(&amp;dh_params);
        gnutls_dh_params_generate2(dh_params, bits);

        return 0;
}
</pre>

<hr>
<a name="OCSP-example"></a>
<div class="header">
<p>
Next: <a href="#Miscellaneous-examples" accesskey="n" rel="next">Miscellaneous examples</a>, Previous: <a href="#Server-examples" accesskey="p" rel="prev">Server examples</a>, Up: <a href="#GnuTLS-application-examples" accesskey="u" rel="up">GnuTLS application examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OCSP-example-1"></a>
<h3 class="section">7.3 OCSP example</h3>

<a name="Generate-OCSP-request"></a><a name="Generate-OCSP-request-1"></a>
<h4 class="subheading">Generate <acronym>OCSP</acronym> request</h4>

<p>A small tool to generate OCSP requests.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/crypto.h&gt;
#include &lt;gnutls/ocsp.h&gt;
#ifndef NO_LIBCURL
#include &lt;curl/curl.h&gt;
#endif
#include &quot;read-file.h&quot;

size_t get_data(void *buffer, size_t size, size_t nmemb, void *userp);
static gnutls_x509_crt_t load_cert(const char *cert_file);
static void _response_info(const gnutls_datum_t * data);
static void
_generate_request(gnutls_datum_t * rdata, gnutls_x509_crt_t cert,
                  gnutls_x509_crt_t issuer, gnutls_datum_t *nonce);
static int
_verify_response(gnutls_datum_t * data, gnutls_x509_crt_t cert,
                 gnutls_x509_crt_t signer, gnutls_datum_t *nonce);

/* This program queries an OCSP server.
   It expects three files. argv[1] containing the certificate to
   be checked, argv[2] holding the issuer for this certificate,
   and argv[3] holding a trusted certificate to verify OCSP's response.
   argv[4] is optional and should hold the server host name.
   
   For simplicity the libcurl library is used.
 */

int main(int argc, char *argv[])
{
        gnutls_datum_t ud, tmp;
        int ret;
        gnutls_datum_t req;
        gnutls_x509_crt_t cert, issuer, signer;
#ifndef NO_LIBCURL
        CURL *handle;
        struct curl_slist *headers = NULL;
#endif
        int v, seq;
        const char *cert_file = argv[1];
        const char *issuer_file = argv[2];
        const char *signer_file = argv[3];
        char *hostname = NULL;
        unsigned char noncebuf[23];
        gnutls_datum_t nonce = { noncebuf, sizeof(noncebuf) };

        gnutls_global_init();

        if (argc &gt; 4)
                hostname = argv[4];

        ret = gnutls_rnd(GNUTLS_RND_NONCE, nonce.data, nonce.size);
        if (ret &lt; 0)
                exit(1);

        cert = load_cert(cert_file);
        issuer = load_cert(issuer_file);
        signer = load_cert(signer_file);

        if (hostname == NULL) {

                for (seq = 0;; seq++) {
                        ret =
                            gnutls_x509_crt_get_authority_info_access(cert,
                                                                      seq,
                                                                      GNUTLS_IA_OCSP_URI,
                                                                      &amp;tmp,
                                                                      NULL);
                        if (ret == GNUTLS_E_UNKNOWN_ALGORITHM)
                                continue;
                        if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) {
                                fprintf(stderr,
                                        &quot;No URI was found in the certificate.\n&quot;);
                                exit(1);
                        }
                        if (ret &lt; 0) {
                                fprintf(stderr, &quot;error: %s\n&quot;,
                                        gnutls_strerror(ret));
                                exit(1);
                        }

                        printf(&quot;CA issuers URI: %.*s\n&quot;, tmp.size,
                               tmp.data);

                        hostname = malloc(tmp.size + 1);
                        memcpy(hostname, tmp.data, tmp.size);
                        hostname[tmp.size] = 0;

                        gnutls_free(tmp.data);
                        break;
                }

        }

        /* Note that the OCSP servers hostname might be available
         * using gnutls_x509_crt_get_authority_info_access() in the issuer's
         * certificate */

        memset(&amp;ud, 0, sizeof(ud));
        fprintf(stderr, &quot;Connecting to %s\n&quot;, hostname);

        _generate_request(&amp;req, cert, issuer, &amp;nonce);

#ifndef NO_LIBCURL
        curl_global_init(CURL_GLOBAL_ALL);

        handle = curl_easy_init();
        if (handle == NULL)
                exit(1);

        headers =
            curl_slist_append(headers,
                              &quot;Content-Type: application/ocsp-request&quot;);

        curl_easy_setopt(handle, CURLOPT_HTTPHEADER, headers);
        curl_easy_setopt(handle, CURLOPT_POSTFIELDS, (void *) req.data);
        curl_easy_setopt(handle, CURLOPT_POSTFIELDSIZE, req.size);
        curl_easy_setopt(handle, CURLOPT_URL, hostname);
        curl_easy_setopt(handle, CURLOPT_WRITEFUNCTION, get_data);
        curl_easy_setopt(handle, CURLOPT_WRITEDATA, &amp;ud);

        ret = curl_easy_perform(handle);
        if (ret != 0) {
                fprintf(stderr, &quot;curl[%d] error %d\n&quot;, __LINE__, ret);
                exit(1);
        }

        curl_easy_cleanup(handle);
#endif

        _response_info(&amp;ud);

        v = _verify_response(&amp;ud, cert, signer, &amp;nonce);

        gnutls_x509_crt_deinit(cert);
        gnutls_x509_crt_deinit(issuer);
        gnutls_x509_crt_deinit(signer);
        gnutls_global_deinit();

        return v;
}

static void _response_info(const gnutls_datum_t * data)
{
        gnutls_ocsp_resp_t resp;
        int ret;
        gnutls_datum buf;

        ret = gnutls_ocsp_resp_init(&amp;resp);
        if (ret &lt; 0)
                exit(1);

        ret = gnutls_ocsp_resp_import(resp, data);
        if (ret &lt; 0)
                exit(1);

        ret = gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_FULL, &amp;buf);
        if (ret != 0)
                exit(1);

        printf(&quot;%.*s&quot;, buf.size, buf.data);
        gnutls_free(buf.data);

        gnutls_ocsp_resp_deinit(resp);
}

static gnutls_x509_crt_t load_cert(const char *cert_file)
{
        gnutls_x509_crt_t crt;
        int ret;
        gnutls_datum_t data;
        size_t size;

        ret = gnutls_x509_crt_init(&amp;crt);
        if (ret &lt; 0)
                exit(1);

        data.data = (void *) read_binary_file(cert_file, &amp;size);
        data.size = size;

        if (!data.data) {
                fprintf(stderr, &quot;Cannot open file: %s\n&quot;, cert_file);
                exit(1);
        }

        ret = gnutls_x509_crt_import(crt, &amp;data, GNUTLS_X509_FMT_PEM);
        free(data.data);
        if (ret &lt; 0) {
                fprintf(stderr, &quot;Cannot import certificate in %s: %s\n&quot;,
                        cert_file, gnutls_strerror(ret));
                exit(1);
        }

        return crt;
}

static void
_generate_request(gnutls_datum_t * rdata, gnutls_x509_crt_t cert,
                  gnutls_x509_crt_t issuer, gnutls_datum_t *nonce)
{
        gnutls_ocsp_req_t req;
        int ret;

        ret = gnutls_ocsp_req_init(&amp;req);
        if (ret &lt; 0)
                exit(1);

        ret = gnutls_ocsp_req_add_cert(req, GNUTLS_DIG_SHA1, issuer, cert);
        if (ret &lt; 0)
                exit(1);


        ret = gnutls_ocsp_req_set_nonce(req, 0, nonce);
        if (ret &lt; 0)
                exit(1);

        ret = gnutls_ocsp_req_export(req, rdata);
        if (ret != 0)
                exit(1);

        gnutls_ocsp_req_deinit(req);

        return;
}

static int
_verify_response(gnutls_datum_t * data, gnutls_x509_crt_t cert,
                 gnutls_x509_crt_t signer, gnutls_datum_t *nonce)
{
        gnutls_ocsp_resp_t resp;
        int ret;
        unsigned verify;
        gnutls_datum_t rnonce;

        ret = gnutls_ocsp_resp_init(&amp;resp);
        if (ret &lt; 0)
                exit(1);

        ret = gnutls_ocsp_resp_import(resp, data);
        if (ret &lt; 0)
                exit(1);

        ret = gnutls_ocsp_resp_check_crt(resp, 0, cert);
        if (ret &lt; 0)
                exit(1);

	ret = gnutls_ocsp_resp_get_nonce(resp, NULL, &amp;rnonce);
	if (ret &lt; 0)
		exit(1);

	if (rnonce.size != nonce-&gt;size || memcmp(nonce-&gt;data, rnonce.data,
		nonce-&gt;size) != 0) {
		exit(1);
	}

        ret = gnutls_ocsp_resp_verify_direct(resp, signer, &amp;verify, 0);
        if (ret &lt; 0)
                exit(1);

        printf(&quot;Verifying OCSP Response: &quot;);
        if (verify == 0)
                printf(&quot;Verification success!\n&quot;);
        else
                printf(&quot;Verification error!\n&quot;);

        if (verify &amp; GNUTLS_OCSP_VERIFY_SIGNER_NOT_FOUND)
                printf(&quot;Signer cert not found\n&quot;);

        if (verify &amp; GNUTLS_OCSP_VERIFY_SIGNER_KEYUSAGE_ERROR)
                printf(&quot;Signer cert keyusage error\n&quot;);

        if (verify &amp; GNUTLS_OCSP_VERIFY_UNTRUSTED_SIGNER)
                printf(&quot;Signer cert is not trusted\n&quot;);

        if (verify &amp; GNUTLS_OCSP_VERIFY_INSECURE_ALGORITHM)
                printf(&quot;Insecure algorithm\n&quot;);

        if (verify &amp; GNUTLS_OCSP_VERIFY_SIGNATURE_FAILURE)
                printf(&quot;Signature failure\n&quot;);

        if (verify &amp; GNUTLS_OCSP_VERIFY_CERT_NOT_ACTIVATED)
                printf(&quot;Signer cert not yet activated\n&quot;);

        if (verify &amp; GNUTLS_OCSP_VERIFY_CERT_EXPIRED)
                printf(&quot;Signer cert expired\n&quot;);

        gnutls_free(rnonce.data);
        gnutls_ocsp_resp_deinit(resp);

        return verify;
}

size_t get_data(void *buffer, size_t size, size_t nmemb, void *userp)
{
        gnutls_datum_t *ud = userp;

        size *= nmemb;

        ud-&gt;data = realloc(ud-&gt;data, size + ud-&gt;size);
        if (ud-&gt;data == NULL) {
                fprintf(stderr, &quot;Not enough memory for the request\n&quot;);
                exit(1);
        }

        memcpy(&amp;ud-&gt;data[ud-&gt;size], buffer, size);
        ud-&gt;size += size;

        return size;
}
</pre>
<hr>
<a name="Miscellaneous-examples"></a>
<div class="header">
<p>
Previous: <a href="#OCSP-example" accesskey="p" rel="prev">OCSP example</a>, Up: <a href="#GnuTLS-application-examples" accesskey="u" rel="up">GnuTLS application examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Miscellaneous-examples-1"></a>
<h3 class="section">7.4 Miscellaneous examples</h3>

<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Checking-for-an-alert" accesskey="1">Checking for an alert</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#X_002e509-certificate-parsing-example" accesskey="2">X.509 certificate parsing example</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Listing-the-ciphersuites-in-a-priority-string" accesskey="3">Listing the ciphersuites in a priority string</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#PKCS12-structure-generation-example" accesskey="4">PKCS12 structure generation example</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Checking-for-an-alert"></a>
<div class="header">
<p>
Next: <a href="#X_002e509-certificate-parsing-example" accesskey="n" rel="next">X.509 certificate parsing example</a>, Up: <a href="#Miscellaneous-examples" accesskey="u" rel="up">Miscellaneous examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Checking-for-an-alert-1"></a>
<h4 class="subsection">7.4.1 Checking for an alert</h4>

<p>This is a function that checks if an alert has been received in the
current session.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;gnutls/gnutls.h&gt;

#include &quot;examples.h&quot;

/* This function will check whether the given return code from
 * a gnutls function (recv/send), is an alert, and will print
 * that alert.
 */
void check_alert(gnutls_session_t session, int ret)
{
        int last_alert;

        if (ret == GNUTLS_E_WARNING_ALERT_RECEIVED
            || ret == GNUTLS_E_FATAL_ALERT_RECEIVED) {
                last_alert = gnutls_alert_get(session);

                /* The check for renegotiation is only useful if we are 
                 * a server, and we had requested a rehandshake.
                 */
                if (last_alert == GNUTLS_A_NO_RENEGOTIATION &amp;&amp;
                    ret == GNUTLS_E_WARNING_ALERT_RECEIVED)
                        printf(&quot;* Received NO_RENEGOTIATION alert. &quot;
                               &quot;Client Does not support renegotiation.\n&quot;);
                else
                        printf(&quot;* Received alert '%d': %s.\n&quot;, last_alert,
                               gnutls_alert_get_name(last_alert));
        }
}
</pre>
<hr>
<a name="X_002e509-certificate-parsing-example"></a>
<div class="header">
<p>
Next: <a href="#Listing-the-ciphersuites-in-a-priority-string" accesskey="n" rel="next">Listing the ciphersuites in a priority string</a>, Previous: <a href="#Checking-for-an-alert" accesskey="p" rel="prev">Checking for an alert</a>, Up: <a href="#Miscellaneous-examples" accesskey="u" rel="up">Miscellaneous examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="X_002e509-certificate-parsing-example-1"></a>
<h4 class="subsection">7.4.2 <acronym>X.509</acronym> certificate parsing example</h4>
<a name="ex_002dx509_002dinfo"></a>
<p>To demonstrate the <acronym>X.509</acronym> parsing capabilities an example program is
listed below.  That program reads the peer&rsquo;s certificate, and prints
information about it.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/x509.h&gt;

#include &quot;examples.h&quot;

static const char *bin2hex(const void *bin, size_t bin_size)
{
        static char printable[110];
        const unsigned char *_bin = bin;
        char *print;
        size_t i;

        if (bin_size &gt; 50)
                bin_size = 50;

        print = printable;
        for (i = 0; i &lt; bin_size; i++) {
                sprintf(print, &quot;%.2x &quot;, _bin[i]);
                print += 2;
        }

        return printable;
}

/* This function will print information about this session's peer
 * certificate.
 */
void print_x509_certificate_info(gnutls_session_t session)
{
        char serial[40];
        char dn[256];
        size_t size;
        unsigned int algo, bits;
        time_t expiration_time, activation_time;
        const gnutls_datum_t *cert_list;
        unsigned int cert_list_size = 0;
        gnutls_x509_crt_t cert;
        gnutls_datum_t cinfo;

        /* This function only works for X.509 certificates.
         */
        if (gnutls_certificate_type_get(session) != GNUTLS_CRT_X509)
                return;

        cert_list = gnutls_certificate_get_peers(session, &amp;cert_list_size);

        printf(&quot;Peer provided %d certificates.\n&quot;, cert_list_size);

        if (cert_list_size &gt; 0) {
                int ret;

                /* we only print information about the first certificate.
                 */
                gnutls_x509_crt_init(&amp;cert);

                gnutls_x509_crt_import(cert, &amp;cert_list[0],
                                       GNUTLS_X509_FMT_DER);

                printf(&quot;Certificate info:\n&quot;);

                /* This is the preferred way of printing short information about
                   a certificate. */

                ret =
                    gnutls_x509_crt_print(cert, GNUTLS_CRT_PRINT_ONELINE,
                                          &amp;cinfo);
                if (ret == 0) {
                        printf(&quot;\t%s\n&quot;, cinfo.data);
                        gnutls_free(cinfo.data);
                }

                /* If you want to extract fields manually for some other reason,
                   below are popular example calls. */

                expiration_time =
                    gnutls_x509_crt_get_expiration_time(cert);
                activation_time =
                    gnutls_x509_crt_get_activation_time(cert);

                printf(&quot;\tCertificate is valid since: %s&quot;,
                       ctime(&amp;activation_time));
                printf(&quot;\tCertificate expires: %s&quot;,
                       ctime(&amp;expiration_time));

                /* Print the serial number of the certificate.
                 */
                size = sizeof(serial);
                gnutls_x509_crt_get_serial(cert, serial, &amp;size);

                printf(&quot;\tCertificate serial number: %s\n&quot;,
                       bin2hex(serial, size));

                /* Extract some of the public key algorithm's parameters
                 */
                algo = gnutls_x509_crt_get_pk_algorithm(cert, &amp;bits);

                printf(&quot;Certificate public key: %s&quot;,
                       gnutls_pk_algorithm_get_name(algo));

                /* Print the version of the X.509
                 * certificate.
                 */
                printf(&quot;\tCertificate version: #%d\n&quot;,
                       gnutls_x509_crt_get_version(cert));

                size = sizeof(dn);
                gnutls_x509_crt_get_dn(cert, dn, &amp;size);
                printf(&quot;\tDN: %s\n&quot;, dn);

                size = sizeof(dn);
                gnutls_x509_crt_get_issuer_dn(cert, dn, &amp;size);
                printf(&quot;\tIssuer's DN: %s\n&quot;, dn);

                gnutls_x509_crt_deinit(cert);

        }
}
</pre>
<hr>
<a name="Listing-the-ciphersuites-in-a-priority-string"></a>
<div class="header">
<p>
Next: <a href="#PKCS12-structure-generation-example" accesskey="n" rel="next">PKCS12 structure generation example</a>, Previous: <a href="#X_002e509-certificate-parsing-example" accesskey="p" rel="prev">X.509 certificate parsing example</a>, Up: <a href="#Miscellaneous-examples" accesskey="u" rel="up">Miscellaneous examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Listing-the-ciphersuites-in-a-priority-string-1"></a>
<h4 class="subsection">7.4.3 Listing the ciphersuites in a priority string</h4>

<p>This is a small program to list the enabled ciphersuites by a 
priority string.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#include &lt;config.h&gt;
#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;gnutls/gnutls.h&gt;

static void print_cipher_suite_list(const char *priorities)
{
        size_t i;
        int ret;
        unsigned int idx;
        const char *name;
        const char *err;
        unsigned char id[2];
        gnutls_protocol_t version;
        gnutls_priority_t pcache;

        if (priorities != NULL) {
                printf(&quot;Cipher suites for %s\n&quot;, priorities);

                ret = gnutls_priority_init(&amp;pcache, priorities, &amp;err);
                if (ret &lt; 0) {
                        fprintf(stderr, &quot;Syntax error at: %s\n&quot;, err);
                        exit(1);
                }

                for (i = 0;; i++) {
                        ret =
                            gnutls_priority_get_cipher_suite_index(pcache,
                                                                   i,
                                                                   &amp;idx);
                        if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
                                break;
                        if (ret == GNUTLS_E_UNKNOWN_CIPHER_SUITE)
                                continue;

                        name =
                            gnutls_cipher_suite_info(idx, id, NULL, NULL,
                                                     NULL, &amp;version);

                        if (name != NULL)
                                printf(&quot;%-50s\t0x%02x, 0x%02x\t%s\n&quot;,
                                       name, (unsigned char) id[0],
                                       (unsigned char) id[1],
                                       gnutls_protocol_get_name(version));
                }

                return;
        }
}

int main(int argc, char **argv)
{
        if (argc &gt; 1)
                print_cipher_suite_list(argv[1]);
        return 0;
}
</pre>
<hr>
<a name="PKCS12-structure-generation-example"></a>
<div class="header">
<p>
Previous: <a href="#Listing-the-ciphersuites-in-a-priority-string" accesskey="p" rel="prev">Listing the ciphersuites in a priority string</a>, Up: <a href="#Miscellaneous-examples" accesskey="u" rel="up">Miscellaneous examples</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="PKCS-_002312-structure-generation-example"></a>
<h4 class="subsection">7.4.4 PKCS #12 structure generation example</h4>

<p>This small program demonstrates the usage of the PKCS #12 API, by generating
such a structure.
</p>
<pre class="verbatim">/* This example code is placed in the public domain. */

#ifdef HAVE_CONFIG_H
#include &lt;config.h&gt;
#endif

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;gnutls/gnutls.h&gt;
#include &lt;gnutls/pkcs12.h&gt;

#include &quot;examples.h&quot;

#define OUTFILE &quot;out.p12&quot;

/* This function will write a pkcs12 structure into a file.
 * cert: is a DER encoded certificate
 * pkcs8_key: is a PKCS #8 encrypted key (note that this must be
 *  encrypted using a PKCS #12 cipher, or some browsers will crash)
 * password: is the password used to encrypt the PKCS #12 packet.
 */
int
write_pkcs12(const gnutls_datum_t * cert,
             const gnutls_datum_t * pkcs8_key, const char *password)
{
        gnutls_pkcs12_t pkcs12;
        int ret, bag_index;
        gnutls_pkcs12_bag_t bag, key_bag;
        char pkcs12_struct[10 * 1024];
        size_t pkcs12_struct_size;
        FILE *fd;

        /* A good idea might be to use gnutls_x509_privkey_get_key_id()
         * to obtain a unique ID.
         */
        gnutls_datum_t key_id = { (void *) &quot;\x00\x00\x07&quot;, 3 };

        gnutls_global_init();

        /* Firstly we create two helper bags, which hold the certificate,
         * and the (encrypted) key.
         */

        gnutls_pkcs12_bag_init(&amp;bag);
        gnutls_pkcs12_bag_init(&amp;key_bag);

        ret =
            gnutls_pkcs12_bag_set_data(bag, GNUTLS_BAG_CERTIFICATE, cert);
        if (ret &lt; 0) {
                fprintf(stderr, &quot;ret: %s\n&quot;, gnutls_strerror(ret));
                return 1;
        }

        /* ret now holds the bag's index.
         */
        bag_index = ret;

        /* Associate a friendly name with the given certificate. Used
         * by browsers.
         */
        gnutls_pkcs12_bag_set_friendly_name(bag, bag_index, &quot;My name&quot;);

        /* Associate the certificate with the key using a unique key
         * ID.
         */
        gnutls_pkcs12_bag_set_key_id(bag, bag_index, &amp;key_id);

        /* use weak encryption for the certificate. 
         */
        gnutls_pkcs12_bag_encrypt(bag, password,
                                  GNUTLS_PKCS_USE_PKCS12_RC2_40);

        /* Now the key.
         */

        ret = gnutls_pkcs12_bag_set_data(key_bag,
                                         GNUTLS_BAG_PKCS8_ENCRYPTED_KEY,
                                         pkcs8_key);
        if (ret &lt; 0) {
                fprintf(stderr, &quot;ret: %s\n&quot;, gnutls_strerror(ret));
                return 1;
        }

        /* Note that since the PKCS #8 key is already encrypted we don't
         * bother encrypting that bag.
         */
        bag_index = ret;

        gnutls_pkcs12_bag_set_friendly_name(key_bag, bag_index, &quot;My name&quot;);

        gnutls_pkcs12_bag_set_key_id(key_bag, bag_index, &amp;key_id);


        /* The bags were filled. Now create the PKCS #12 structure.
         */
        gnutls_pkcs12_init(&amp;pkcs12);

        /* Insert the two bags in the PKCS #12 structure.
         */

        gnutls_pkcs12_set_bag(pkcs12, bag);
        gnutls_pkcs12_set_bag(pkcs12, key_bag);


        /* Generate a message authentication code for the PKCS #12
         * structure.
         */
        gnutls_pkcs12_generate_mac(pkcs12, password);

        pkcs12_struct_size = sizeof(pkcs12_struct);
        ret =
            gnutls_pkcs12_export(pkcs12, GNUTLS_X509_FMT_DER,
                                 pkcs12_struct, &amp;pkcs12_struct_size);
        if (ret &lt; 0) {
                fprintf(stderr, &quot;ret: %s\n&quot;, gnutls_strerror(ret));
                return 1;
        }

        fd = fopen(OUTFILE, &quot;w&quot;);
        if (fd == NULL) {
                fprintf(stderr, &quot;cannot open file\n&quot;);
                return 1;
        }
        fwrite(pkcs12_struct, 1, pkcs12_struct_size, fd);
        fclose(fd);

        gnutls_pkcs12_bag_deinit(bag);
        gnutls_pkcs12_bag_deinit(key_bag);
        gnutls_pkcs12_deinit(pkcs12);

        return 0;
}
</pre>

<hr>
<a name="Using-GnuTLS-as-a-cryptographic-library"></a>
<div class="header">
<p>
Next: <a href="#Other-included-programs" accesskey="n" rel="next">Other included programs</a>, Previous: <a href="#GnuTLS-application-examples" accesskey="p" rel="prev">GnuTLS application examples</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Using-GnuTLS-as-a-cryptographic-library-1"></a>
<h2 class="chapter">8 Using GnuTLS as a cryptographic library</h2>

<p><acronym>GnuTLS</acronym> is not a low-level cryptographic library, i.e., 
it does not provide access to basic cryptographic primitives. However
it abstracts the internal cryptographic back-end (see <a href="#Cryptographic-Backend">Cryptographic Backend</a>),
providing symmetric crypto, hash and HMAC algorithms, as well access
to the random number generation. For a low-level crypto API the usage of nettle
<a name="DOCF19" href="#FOOT19"><sup>19</sup></a> library is recommended.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Symmetric-algorithms" accesskey="1">Symmetric algorithms</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Public-key-algorithms" accesskey="2">Public key algorithms</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Hash-and-MAC-functions" accesskey="3">Hash and MAC functions</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Random-number-generation" accesskey="4">Random number generation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Overriding-algorithms" accesskey="5">Overriding algorithms</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Symmetric-algorithms"></a>
<div class="header">
<p>
Next: <a href="#Public-key-algorithms" accesskey="n" rel="next">Public key algorithms</a>, Up: <a href="#Using-GnuTLS-as-a-cryptographic-library" accesskey="u" rel="up">Using GnuTLS as a cryptographic library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Symmetric-algorithms-1"></a>
<h3 class="section">8.1 Symmetric algorithms</h3>
<a name="index-symmetric-algorithms"></a>
<a name="index-symmetric-cryptography"></a>

<p>The available functions to access symmetric crypto algorithms operations
are shown below. The supported algorithms are the algorithms required by the TLS protocol.
They are listed in <a href="#gnutls_005fcipher_005falgorithm_005ft">Figure 8.1</a>.
</p>
<div class="float"><a name="gnutls_005fcipher_005falgorithm_005ft"></a>


<dl compact="compact">
<dt><code>GNUTLS_CIPHER_UNKNOWN</code></dt>
<dd><p>Value to identify an unknown/unsupported algorithm.
</p></dd>
<dt><code>GNUTLS_CIPHER_NULL</code></dt>
<dd><p>The NULL (identity) encryption algorithm.
</p></dd>
<dt><code>GNUTLS_CIPHER_ARCFOUR_128</code></dt>
<dd><p>ARCFOUR stream cipher with 128-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_3DES_CBC</code></dt>
<dd><p>3DES in CBC mode.
</p></dd>
<dt><code>GNUTLS_CIPHER_AES_128_CBC</code></dt>
<dd><p>AES in CBC mode with 128-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_AES_256_CBC</code></dt>
<dd><p>AES in CBC mode with 256-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_ARCFOUR_40</code></dt>
<dd><p>ARCFOUR stream cipher with 40-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_CAMELLIA_128_CBC</code></dt>
<dd><p>Camellia in CBC mode with 128-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_CAMELLIA_256_CBC</code></dt>
<dd><p>Camellia in CBC mode with 256-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_AES_192_CBC</code></dt>
<dd><p>AES in CBC mode with 192-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_AES_128_GCM</code></dt>
<dd><p>AES in GCM mode with 128-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_AES_256_GCM</code></dt>
<dd><p>AES in GCM mode with 256-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_CAMELLIA_192_CBC</code></dt>
<dd><p>Camellia in CBC mode with 192-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_SALSA20_256</code></dt>
<dd><p>Salsa20 with 256-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_ESTREAM_SALSA20_256</code></dt>
<dd><p>Estream&rsquo;s Salsa20 variant with 256-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_CAMELLIA_128_GCM</code></dt>
<dd><p>CAMELLIA in GCM mode with 128-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_CAMELLIA_256_GCM</code></dt>
<dd><p>CAMELLIA in GCM mode with 256-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_RC2_40_CBC</code></dt>
<dd><p>RC2 in CBC mode with 40-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_DES_CBC</code></dt>
<dd><p>DES in CBC mode (56-bit keys).
</p></dd>
<dt><code>GNUTLS_CIPHER_AES_128_CCM</code></dt>
<dd><p>AES in CCM mode with 128-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_AES_256_CCM</code></dt>
<dd><p>AES in CCM mode with 256-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_AES_128_CCM_8</code></dt>
<dd><p>AES in CCM mode with 64-bit tag and 128-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_AES_256_CCM_8</code></dt>
<dd><p>AES in CCM mode with 64-bit tag and 256-bit keys.
</p></dd>
<dt><code>GNUTLS_CIPHER_CHACHA20_POLY1305</code></dt>
<dd><p>The Chacha20 cipher with the Poly1305 authenticator (AEAD).
</p></dd>
<dt><code>GNUTLS_CIPHER_IDEA_PGP_CFB</code></dt>
<dd><p>IDEA in CFB mode (placeholder - unsupported).
</p></dd>
<dt><code>GNUTLS_CIPHER_3DES_PGP_CFB</code></dt>
<dd><p>3DES in CFB mode (placeholder - unsupported).
</p></dd>
<dt><code>GNUTLS_CIPHER_CAST5_PGP_CFB</code></dt>
<dd><p>CAST5 in CFB mode (placeholder - unsupported).
</p></dd>
<dt><code>GNUTLS_CIPHER_BLOWFISH_PGP_CFB</code></dt>
<dd><p>Blowfish in CFB mode (placeholder - unsupported).
</p></dd>
<dt><code>GNUTLS_CIPHER_SAFER_SK128_PGP_CFB</code></dt>
<dd><p>Safer-SK in CFB mode with 128-bit keys (placeholder - unsupported).
</p></dd>
<dt><code>GNUTLS_CIPHER_AES128_PGP_CFB</code></dt>
<dd><p>AES in CFB mode with 128-bit keys (placeholder - unsupported).
</p></dd>
<dt><code>GNUTLS_CIPHER_AES192_PGP_CFB</code></dt>
<dd><p>AES in CFB mode with 192-bit keys (placeholder - unsupported).
</p></dd>
<dt><code>GNUTLS_CIPHER_AES256_PGP_CFB</code></dt>
<dd><p>AES in CFB mode with 256-bit keys (placeholder - unsupported).
</p></dd>
<dt><code>GNUTLS_CIPHER_TWOFISH_PGP_CFB</code></dt>
<dd><p>Twofish in CFB mode (placeholder - unsupported).
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 8.1: </strong>The supported ciphers.</p></div></div>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fcipher_005finit">gnutls_cipher_init</a> (gnutls_cipher_hd_t * <var>handle</var>, gnutls_cipher_algorithm_t <var>cipher</var>, const gnutls_datum_t * <var>key</var>, const gnutls_datum_t * <var>iv</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcipher_005fencrypt2">gnutls_cipher_encrypt2</a> (gnutls_cipher_hd_t <var>handle</var>, const void * <var>ptext</var>, size_t <var>ptext_len</var>, void * <var>ctext</var>, size_t <var>ctext_len</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcipher_005fdecrypt2">gnutls_cipher_decrypt2</a> (gnutls_cipher_hd_t <var>handle</var>, const void * <var>ctext</var>, size_t <var>ctext_len</var>, void * <var>ptext</var>, size_t <var>ptext_len</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fcipher_005fset_005fiv">gnutls_cipher_set_iv</a> (gnutls_cipher_hd_t <var>handle</var>, void * <var>iv</var>, size_t <var>ivlen</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fcipher_005fdeinit">gnutls_cipher_deinit</a> (gnutls_cipher_hd_t <var>handle</var>)</code></dt>
</dl>

<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fcipher_005fadd_005fauth">gnutls_cipher_add_auth</a> (gnutls_cipher_hd_t <var>handle</var>, const void * <var>ptext</var>, size_t <var>ptext_size</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fcipher_005ftag">gnutls_cipher_tag</a> (gnutls_cipher_hd_t <var>handle</var>, void * <var>tag</var>, size_t <var>tag_size</var>)</code></dt>
</dl>
<p>While the latter two functions allow the same API can be used with authenticated encryption ciphers, 
it is recommended to use the following functions which are solely for AEAD ciphers. The latter
API is designed to be simple to use and also hard to misuse, by handling the tag verification
and addition in transparent way.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005faead_005fcipher_005finit">gnutls_aead_cipher_init</a> (gnutls_aead_cipher_hd_t * <var>handle</var>, gnutls_cipher_algorithm_t <var>cipher</var>, const gnutls_datum_t * <var>key</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005faead_005fcipher_005fencrypt">gnutls_aead_cipher_encrypt</a> (gnutls_aead_cipher_hd_t <var>handle</var>, const void * <var>nonce</var>, size_t <var>nonce_len</var>, const void * <var>auth</var>, size_t <var>auth_len</var>, size_t <var>tag_size</var>, const void * <var>ptext</var>, size_t <var>ptext_len</var>, void * <var>ctext</var>, size_t * <var>ctext_len</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005faead_005fcipher_005fdecrypt">gnutls_aead_cipher_decrypt</a> (gnutls_aead_cipher_hd_t <var>handle</var>, const void * <var>nonce</var>, size_t <var>nonce_len</var>, const void * <var>auth</var>, size_t <var>auth_len</var>, size_t <var>tag_size</var>, const void * <var>ctext</var>, size_t <var>ctext_len</var>, void * <var>ptext</var>, size_t * <var>ptext_len</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005faead_005fcipher_005fdeinit">gnutls_aead_cipher_deinit</a> (gnutls_aead_cipher_hd_t <var>handle</var>)</code></dt>
</dl>

<hr>
<a name="Public-key-algorithms"></a>
<div class="header">
<p>
Next: <a href="#Hash-and-MAC-functions" accesskey="n" rel="next">Hash and MAC functions</a>, Previous: <a href="#Symmetric-algorithms" accesskey="p" rel="prev">Symmetric algorithms</a>, Up: <a href="#Using-GnuTLS-as-a-cryptographic-library" accesskey="u" rel="up">Using GnuTLS as a cryptographic library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Public-key-algorithms-1"></a>
<h3 class="section">8.2 Public key algorithms</h3>
<a name="index-public-key-algorithms"></a>

<p>Public key cryptography algorithms such as RSA, DSA and ECDSA, can be
accessed using the abstract key API in <a href="#Abstract-key-types">Abstract key types</a>. This
is a high level API with the advantage of transparently handling keys
in memory and keys present in smart cards.
</p>
<a name="PKCS-_00237-signing"></a>
<h4 class="subsection">8.2.1 PKCS #7 signing</h4>
<a name="index-PKCS-_00237"></a>
<a name="index-file-signing"></a>

<p>The PKCS #7 format is common format used for digital signatures. It allows to sign
by embedding the data into the signature, or creating detached signatures of the data,
including a timestamp, additional certificates etc. In certain cases this format is also
used to transport lists of certificates and CRLs.
</p>
<p>The basic functions to initialize, deinitialize, import, export or print information
about a PKCS #7 structure are shown below.
</p><dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005finit">gnutls_pkcs7_init</a> (gnutls_pkcs7_t * <var>pkcs7</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fpkcs7_005fdeinit">gnutls_pkcs7_deinit</a> (gnutls_pkcs7_t <var>pkcs7</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fexport2">gnutls_pkcs7_export2</a> (gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_crt_fmt_t <var>format</var>, gnutls_datum_t * <var>out</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fimport">gnutls_pkcs7_import</a> (gnutls_pkcs7_t <var>pkcs7</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fprint">gnutls_pkcs7_print</a> (gnutls_pkcs7_t <var>pkcs7</var>, gnutls_certificate_print_formats_t <var>format</var>, gnutls_datum_t * <var>out</var>)</code></dt>
</dl>

<p>The following functions allow the verification of a structure using either a trust list, or
individual certificates. The <a href="#gnutls_005fpkcs7_005fsign">gnutls_pkcs7_sign</a> function is the data signing function.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fverify_005fdirect">gnutls_pkcs7_verify_direct</a> (gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_crt_t <var>signer</var>, unsigned <var>idx</var>, const gnutls_datum_t * <var>data</var>, unsigned <var>flags</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fverify">gnutls_pkcs7_verify</a> (gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_trust_list_t <var>tl</var>, gnutls_typed_vdata_st * <var>vdata</var>, unsigned int <var>vdata_size</var>, unsigned <var>idx</var>, const gnutls_datum_t * <var>data</var>, unsigned <var>flags</var>)</code></dt>
</dl>




<dl>
<dt><a name="index-gnutls_005fpkcs7_005fsign"></a>Function: <em>int</em> <strong>gnutls_pkcs7_sign</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_crt_t <var>signer</var>, gnutls_privkey_t <var>signer_key</var>, const gnutls_datum_t * <var>data</var>, gnutls_pkcs7_attrs_t <var>signed_attrs</var>, gnutls_pkcs7_attrs_t <var>unsigned_attrs</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>pkcs7</var>: should contain a <code>gnutls_pkcs7_t</code>  type
</p>
<p><var>signer</var>: the certificate to sign the structure
</p>
<p><var>signer_key</var>: the key to sign the structure
</p>
<p><var>data</var>: The data to be signed or <code>NULL</code>  if the data are already embedded
</p>
<p><var>signed_attrs</var>: Any additional attributes to be included in the signed ones (or <code>NULL</code> )
</p>
<p><var>unsigned_attrs</var>: Any additional attributes to be included in the unsigned ones (or <code>NULL</code> )
</p>
<p><var>dig</var>: The digest algorithm to use for signing
</p>
<p><var>flags</var>: Should be zero or one of <code>GNUTLS_PKCS7</code>  flags
</p>
<p>This function will add a signature in the provided PKCS <code>7</code>  structure
for the provided data. Multiple signatures can be made with different
signers.
</p>
<p>The available flags are:
<code>GNUTLS_PKCS7_EMBED_DATA</code> , <code>GNUTLS_PKCS7_INCLUDE_TIME</code> , <code>GNUTLS_PKCS7_INCLUDE_CERT</code> ,
and <code>GNUTLS_PKCS7_WRITE_SPKI</code> . They are explained in the <code>gnutls_pkcs7_sign_flags</code> 
definition.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. 
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<div class="float"><a name="gnutls_005fpkcs7_005fsign_005fflags"></a>


<dl compact="compact">
<dt><code>GNUTLS_PKCS7_EMBED_DATA</code></dt>
<dd><p>The signed data will be embedded in the structure.
</p></dd>
<dt><code>GNUTLS_PKCS7_INCLUDE_TIME</code></dt>
<dd><p>The signing time will be included in the structure.
</p></dd>
<dt><code>GNUTLS_PKCS7_INCLUDE_CERT</code></dt>
<dd><p>The signer&rsquo;s certificate will be included in the cert list.
</p></dd>
<dt><code>GNUTLS_PKCS7_WRITE_SPKI</code></dt>
<dd><p>Use the signer&rsquo;s key identifier instead of name.
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 8.2: </strong>Flags applicable to gnutls_pkcs7_sign()</p></div></div>
<p>Other helper functions which allow to access the signatures, or certificates attached
in the structure are listed below.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fget_005fsignature_005fcount">gnutls_pkcs7_get_signature_count</a> (gnutls_pkcs7_t <var>pkcs7</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fget_005fsignature_005finfo">gnutls_pkcs7_get_signature_info</a> (gnutls_pkcs7_t <var>pkcs7</var>, unsigned <var>idx</var>, gnutls_pkcs7_signature_info_st * <var>info</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fget_005fcrt_005fcount">gnutls_pkcs7_get_crt_count</a> (gnutls_pkcs7_t <var>pkcs7</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fget_005fcrt_005fraw2">gnutls_pkcs7_get_crt_raw2</a> (gnutls_pkcs7_t <var>pkcs7</var>, int <var>indx</var>, gnutls_datum_t * <var>cert</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fget_005fcrl_005fcount">gnutls_pkcs7_get_crl_count</a> (gnutls_pkcs7_t <var>pkcs7</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fget_005fcrl_005fraw2">gnutls_pkcs7_get_crl_raw2</a> (gnutls_pkcs7_t <var>pkcs7</var>, int <var>indx</var>, gnutls_datum_t * <var>crl</var>)</code></dt>
</dl>

<p>To append certificates, or CRLs in the structure the following functions are provided.
</p><dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fset_005fcrt_005fraw">gnutls_pkcs7_set_crt_raw</a> (gnutls_pkcs7_t <var>pkcs7</var>, const gnutls_datum_t * <var>crt</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fset_005fcrt">gnutls_pkcs7_set_crt</a> (gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_crt_t <var>crt</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fset_005fcrl_005fraw">gnutls_pkcs7_set_crl_raw</a> (gnutls_pkcs7_t <var>pkcs7</var>, const gnutls_datum_t * <var>crl</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fpkcs7_005fset_005fcrl">gnutls_pkcs7_set_crl</a> (gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_crl_t <var>crl</var>)</code></dt>
</dl>

<hr>
<a name="Hash-and-MAC-functions"></a>
<div class="header">
<p>
Next: <a href="#Random-number-generation" accesskey="n" rel="next">Random number generation</a>, Previous: <a href="#Public-key-algorithms" accesskey="p" rel="prev">Public key algorithms</a>, Up: <a href="#Using-GnuTLS-as-a-cryptographic-library" accesskey="u" rel="up">Using GnuTLS as a cryptographic library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Hash-and-MAC-functions-1"></a>
<h3 class="section">8.3 Hash and MAC functions</h3>
<a name="index-hash-functions"></a>
<a name="index-HMAC-functions"></a>
<a name="index-MAC-functions"></a>

<p>The available operations to access hash functions and hash-MAC (HMAC) algorithms
are shown below. HMAC algorithms provided keyed hash functionality. The supported MAC and HMAC
algorithms are listed in <a href="#gnutls_005fmac_005falgorithm_005ft">Figure 8.3</a>.
</p>
<div class="float"><a name="gnutls_005fmac_005falgorithm_005ft"></a>


<dl compact="compact">
<dt><code>GNUTLS_MAC_UNKNOWN</code></dt>
<dd><p>Unknown MAC algorithm.
</p></dd>
<dt><code>GNUTLS_MAC_NULL</code></dt>
<dd><p>NULL MAC algorithm (empty output).
</p></dd>
<dt><code>GNUTLS_MAC_MD5</code></dt>
<dd><p>HMAC-MD5 algorithm.
</p></dd>
<dt><code>GNUTLS_MAC_SHA1</code></dt>
<dd><p>HMAC-SHA-1 algorithm.
</p></dd>
<dt><code>GNUTLS_MAC_RMD160</code></dt>
<dd><p>HMAC-RMD160 algorithm.
</p></dd>
<dt><code>GNUTLS_MAC_MD2</code></dt>
<dd><p>HMAC-MD2 algorithm.
</p></dd>
<dt><code>GNUTLS_MAC_SHA256</code></dt>
<dd><p>HMAC-SHA-256 algorithm.
</p></dd>
<dt><code>GNUTLS_MAC_SHA384</code></dt>
<dd><p>HMAC-SHA-384 algorithm.
</p></dd>
<dt><code>GNUTLS_MAC_SHA512</code></dt>
<dd><p>HMAC-SHA-512 algorithm.
</p></dd>
<dt><code>GNUTLS_MAC_SHA224</code></dt>
<dd><p>HMAC-SHA-224 algorithm.
</p></dd>
<dt><code>GNUTLS_MAC_AEAD</code></dt>
<dd><p>MAC implicit through AEAD cipher.
</p></dd>
<dt><code>GNUTLS_MAC_UMAC_96</code></dt>
<dd><p>The UMAC-96 MAC algorithm.
</p></dd>
<dt><code>GNUTLS_MAC_UMAC_128</code></dt>
<dd><p>The UMAC-128 MAC algorithm.
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 8.3: </strong>The supported MAC and HMAC algorithms.</p></div></div>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fhmac_005finit">gnutls_hmac_init</a> (gnutls_hmac_hd_t * <var>dig</var>, gnutls_mac_algorithm_t <var>algorithm</var>, const void * <var>key</var>, size_t <var>keylen</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fhmac">gnutls_hmac</a> (gnutls_hmac_hd_t <var>handle</var>, const void * <var>ptext</var>, size_t <var>ptext_len</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fhmac_005foutput">gnutls_hmac_output</a> (gnutls_hmac_hd_t <var>handle</var>, void * <var>digest</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fhmac_005fdeinit">gnutls_hmac_deinit</a> (gnutls_hmac_hd_t <var>handle</var>, void * <var>digest</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fhmac_005fget_005flen">gnutls_hmac_get_len</a> (gnutls_mac_algorithm_t <var>algorithm</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fhmac_005ffast">gnutls_hmac_fast</a> (gnutls_mac_algorithm_t <var>algorithm</var>, const void * <var>key</var>, size_t <var>keylen</var>, const void * <var>ptext</var>, size_t <var>ptext_len</var>, void * <var>digest</var>)</code></dt>
</dl>

<p>The available functions to access hash functions are shown below. The supported hash functions
are shown in <a href="#gnutls_005fdigest_005falgorithm_005ft">Figure 8.4</a>.
</p>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005fhash_005finit">gnutls_hash_init</a> (gnutls_hash_hd_t * <var>dig</var>, gnutls_digest_algorithm_t <var>algorithm</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fhash">gnutls_hash</a> (gnutls_hash_hd_t <var>handle</var>, const void * <var>ptext</var>, size_t <var>ptext_len</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fhash_005foutput">gnutls_hash_output</a> (gnutls_hash_hd_t <var>handle</var>, void * <var>digest</var>)</code></dt>
<dt><code><var>void</var> <a href="#gnutls_005fhash_005fdeinit">gnutls_hash_deinit</a> (gnutls_hash_hd_t <var>handle</var>, void * <var>digest</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fhash_005fget_005flen">gnutls_hash_get_len</a> (gnutls_digest_algorithm_t <var>algorithm</var>)</code></dt>
<dt><code><var>int</var> <a href="#gnutls_005fhash_005ffast">gnutls_hash_fast</a> (gnutls_digest_algorithm_t <var>algorithm</var>, const void * <var>ptext</var>, size_t <var>ptext_len</var>, void * <var>digest</var>)</code></dt>
</dl>
<dl compact="compact">
<dt><code><var>int</var> <a href="#gnutls_005ffingerprint">gnutls_fingerprint</a> (gnutls_digest_algorithm_t <var>algo</var>, const gnutls_datum_t * <var>data</var>, void * <var>result</var>, size_t * <var>result_size</var>)</code></dt>
</dl>

<div class="float"><a name="gnutls_005fdigest_005falgorithm_005ft"></a>


<dl compact="compact">
<dt><code>GNUTLS_DIG_UNKNOWN</code></dt>
<dd><p>Unknown hash algorithm.
</p></dd>
<dt><code>GNUTLS_DIG_NULL</code></dt>
<dd><p>NULL hash algorithm (empty output).
</p></dd>
<dt><code>GNUTLS_DIG_MD5</code></dt>
<dd><p>MD5 algorithm.
</p></dd>
<dt><code>GNUTLS_DIG_SHA1</code></dt>
<dd><p>SHA-1 algorithm.
</p></dd>
<dt><code>GNUTLS_DIG_RMD160</code></dt>
<dd><p>RMD160 algorithm.
</p></dd>
<dt><code>GNUTLS_DIG_MD2</code></dt>
<dd><p>MD2 algorithm.
</p></dd>
<dt><code>GNUTLS_DIG_SHA256</code></dt>
<dd><p>SHA-256 algorithm.
</p></dd>
<dt><code>GNUTLS_DIG_SHA384</code></dt>
<dd><p>SHA-384 algorithm.
</p></dd>
<dt><code>GNUTLS_DIG_SHA512</code></dt>
<dd><p>SHA-512 algorithm.
</p></dd>
<dt><code>GNUTLS_DIG_SHA224</code></dt>
<dd><p>SHA-224 algorithm.
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 8.4: </strong>The supported hash algorithms.</p></div></div>
<hr>
<a name="Random-number-generation"></a>
<div class="header">
<p>
Next: <a href="#Overriding-algorithms" accesskey="n" rel="next">Overriding algorithms</a>, Previous: <a href="#Hash-and-MAC-functions" accesskey="p" rel="prev">Hash and MAC functions</a>, Up: <a href="#Using-GnuTLS-as-a-cryptographic-library" accesskey="u" rel="up">Using GnuTLS as a cryptographic library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Random-number-generation-1"></a>
<h3 class="section">8.4 Random number generation</h3>
<a name="index-random-numbers"></a>

<p>Access to the random number generator is provided using the <a href="#gnutls_005frnd">gnutls_rnd</a>
function. It allows obtaining random data of various levels.
</p>
<div class="float"><a name="gnutls_005frnd_005flevel_005ft"></a>


<dl compact="compact">
<dt><code>GNUTLS_RND_NONCE</code></dt>
<dd><p>Non-predictable random number.  Fatal in parts
of session if broken, i.e., vulnerable to statistical analysis.
</p></dd>
<dt><code>GNUTLS_RND_RANDOM</code></dt>
<dd><p>Pseudo-random cryptographic random number.
Fatal in session if broken.
</p></dd>
<dt><code>GNUTLS_RND_KEY</code></dt>
<dd><p>Fatal in many sessions if broken.
</p></dd>
</dl>

<div class="float-caption"><p><strong>Figure 8.5: </strong>The random number levels.</p></div></div>



<dl>
<dt><a name="index-gnutls_005frnd"></a>Function: <em>int</em> <strong>gnutls_rnd</strong> <em>(gnutls_rnd_level_t <var>level</var>, void * <var>data</var>, size_t <var>len</var>)</em></dt>
<dd><p><var>level</var>: a security level
</p>
<p><var>data</var>: place to store random bytes
</p>
<p><var>len</var>: The requested size
</p>
<p>This function will generate random data and store it to output
buffer.
</p>
<p>This function is thread-safe and also fork-safe.
</p>
<p><strong>Returns:</strong> Zero on success, or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<hr>
<a name="Overriding-algorithms"></a>
<div class="header">
<p>
Previous: <a href="#Random-number-generation" accesskey="p" rel="prev">Random number generation</a>, Up: <a href="#Using-GnuTLS-as-a-cryptographic-library" accesskey="u" rel="up">Using GnuTLS as a cryptographic library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Overriding-algorithms-1"></a>
<h3 class="section">8.5 Overriding algorithms</h3>
<a name="index-overriding-algorithms"></a>

<p>In systems which provide a hardware accelerated cipher implementation
that is not directly supported by GnuTLS, it is possible to utilize it.
There are functions which allow overriding the default cipher, digest and MAC
implementations. Those are described below.
</p>
<p>To override public key operations see <a href="#Abstract-private-keys">Abstract private keys</a>.
</p>




<dl>
<dt><a name="index-gnutls_005fcrypto_005fregister_005fcipher"></a>Function: <em>int</em> <strong>gnutls_crypto_register_cipher</strong> <em>(gnutls_cipher_algorithm_t <var>algorithm</var>, int <var>priority</var>, gnutls_cipher_init_func <var>init</var>, gnutls_cipher_setkey_func <var>setkey</var>, gnutls_cipher_setiv_func <var>setiv</var>, gnutls_cipher_encrypt_func <var>encrypt</var>, gnutls_cipher_decrypt_func <var>decrypt</var>, gnutls_cipher_deinit_func <var>deinit</var>)</em></dt>
<dd><p><var>algorithm</var>: is the gnutls algorithm identifier
</p>
<p><var>priority</var>: is the priority of the algorithm
</p>
<p><var>init</var>: A function which initializes the cipher
</p>
<p><var>setkey</var>: A function which sets the key of the cipher
</p>
<p><var>setiv</var>: A function which sets the nonce/IV of the cipher (non-AEAD)
</p>
<p><var>encrypt</var>: A function which performs encryption (non-AEAD)
</p>
<p><var>decrypt</var>: A function which performs decryption (non-AEAD)
</p>
<p><var>deinit</var>: A function which deinitializes the cipher
</p>
<p>This function will register a cipher algorithm to be used by
gnutls.  Any algorithm registered will override the included
algorithms and by convention kernel implemented algorithms have
priority of 90 and CPU-assisted of 80.  The algorithm with the lowest priority will be
used by gnutls.
</p>
<p>In the case the registered init or setkey functions return <code>GNUTLS_E_NEED_FALLBACK</code> ,
GnuTLS will attempt to use the next in priority registered cipher.
</p>
<p>The functions which are marked as non-AEAD they are not required when
registering a cipher to be used with the new AEAD API introduced in
GnuTLS 3.4.0. Internally GnuTLS uses the new AEAD API.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fcrypto_005fregister_005faead_005fcipher"></a>Function: <em>int</em> <strong>gnutls_crypto_register_aead_cipher</strong> <em>(gnutls_cipher_algorithm_t <var>algorithm</var>, int <var>priority</var>, gnutls_cipher_init_func <var>init</var>, gnutls_cipher_setkey_func <var>setkey</var>, gnutls_cipher_aead_encrypt_func <var>aead_encrypt</var>, gnutls_cipher_aead_decrypt_func <var>aead_decrypt</var>, gnutls_cipher_deinit_func <var>deinit</var>)</em></dt>
<dd><p><var>algorithm</var>: is the gnutls AEAD cipher identifier
</p>
<p><var>priority</var>: is the priority of the algorithm
</p>
<p><var>init</var>: A function which initializes the cipher
</p>
<p><var>setkey</var>: A function which sets the key of the cipher
</p>
<p><var>aead_encrypt</var>: Perform the AEAD encryption
</p>
<p><var>aead_decrypt</var>: Perform the AEAD decryption
</p>
<p><var>deinit</var>: A function which deinitializes the cipher
</p>
<p>This function will register a cipher algorithm to be used by
gnutls.  Any algorithm registered will override the included
algorithms and by convention kernel implemented algorithms have
priority of 90 and CPU-assisted of 80.  The algorithm with the lowest priority will be
used by gnutls.
</p>
<p>In the case the registered init or setkey functions return <code>GNUTLS_E_NEED_FALLBACK</code> ,
GnuTLS will attempt to use the next in priority registered cipher.
</p>
<p>The functions registered will be used with the new AEAD API introduced in
GnuTLS 3.4.0. Internally GnuTLS uses the new AEAD API.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fcrypto_005fregister_005fmac"></a>Function: <em>int</em> <strong>gnutls_crypto_register_mac</strong> <em>(gnutls_mac_algorithm_t <var>algorithm</var>, int <var>priority</var>, gnutls_mac_init_func <var>init</var>, gnutls_mac_setkey_func <var>setkey</var>, gnutls_mac_setnonce_func <var>setnonce</var>, gnutls_mac_hash_func <var>hash</var>, gnutls_mac_output_func <var>output</var>, gnutls_mac_deinit_func <var>deinit</var>, gnutls_mac_fast_func <var>hash_fast</var>)</em></dt>
<dd><p><var>algorithm</var>: is the gnutls MAC identifier
</p>
<p><var>priority</var>: is the priority of the algorithm
</p>
<p><var>init</var>: A function which initializes the MAC
</p>
<p><var>setkey</var>: A function which sets the key of the MAC
</p>
<p><var>setnonce</var>: A function which sets the nonce for the mac (may be <code>NULL</code>  for common MAC algorithms)
</p>
<p><var>hash</var>: Perform the hash operation
</p>
<p><var>output</var>: Provide the output of the MAC
</p>
<p><var>deinit</var>: A function which deinitializes the MAC
</p>
<p><var>hash_fast</var>: Perform the MAC operation in one go
</p>
<p>This function will register a MAC algorithm to be used by gnutls.
Any algorithm registered will override the included algorithms and
by convention kernel implemented algorithms have priority of 90
and CPU-assisted of 80.
The algorithm with the lowest priority will be used by gnutls.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>




<dl>
<dt><a name="index-gnutls_005fcrypto_005fregister_005fdigest"></a>Function: <em>int</em> <strong>gnutls_crypto_register_digest</strong> <em>(gnutls_digest_algorithm_t <var>algorithm</var>, int <var>priority</var>, gnutls_digest_init_func <var>init</var>, gnutls_digest_hash_func <var>hash</var>, gnutls_digest_output_func <var>output</var>, gnutls_digest_deinit_func <var>deinit</var>, gnutls_digest_fast_func <var>hash_fast</var>)</em></dt>
<dd><p><var>algorithm</var>: is the gnutls digest identifier
</p>
<p><var>priority</var>: is the priority of the algorithm
</p>
<p><var>init</var>: A function which initializes the digest
</p>
<p><var>hash</var>: Perform the hash operation
</p>
<p><var>output</var>: Provide the output of the digest
</p>
<p><var>deinit</var>: A function which deinitializes the digest
</p>
<p><var>hash_fast</var>: Perform the digest operation in one go
</p>
<p>This function will register a digest algorithm to be used by gnutls.
Any algorithm registered will override the included algorithms and
by convention kernel implemented algorithms have priority of 90
and CPU-assisted of 80.
The algorithm with the lowest priority will be used by gnutls.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<hr>
<a name="Other-included-programs"></a>
<div class="header">
<p>
Next: <a href="#Internal-architecture-of-GnuTLS" accesskey="n" rel="next">Internal architecture of GnuTLS</a>, Previous: <a href="#Using-GnuTLS-as-a-cryptographic-library" accesskey="p" rel="prev">Using GnuTLS as a cryptographic library</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Other-included-programs-1"></a>
<h2 class="chapter">9 Other included programs</h2>

<p>Included with <acronym>GnuTLS</acronym> are also a few command line tools that
let you use the library for common tasks without writing an
application.  The applications are discussed in this chapter.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#gnutls_002dcli-Invocation" accesskey="1">gnutls-cli Invocation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Invoking gnutls-cli
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#gnutls_002dserv-Invocation" accesskey="2">gnutls-serv Invocation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Invoking gnutls-serv
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#gnutls_002dcli_002ddebug-Invocation" accesskey="3">gnutls-cli-debug Invocation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Invoking gnutls-cli-debug
</td></tr>
</table>

<hr>
<a name="gnutls_002dcli-Invocation"></a>
<div class="header">
<p>
Next: <a href="#gnutls_002dserv-Invocation" accesskey="n" rel="next">gnutls-serv Invocation</a>, Up: <a href="#Other-included-programs" accesskey="u" rel="up">Other included programs</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Invoking-gnutls_002dcli"></a>
<h3 class="section">9.1 Invoking gnutls-cli</h3>
<a name="index-gnutls_002dcli"></a>


<p>Simple client program to set up a TLS connection to some other computer. 
It sets up a TLS connection and forwards data from the standard input to the secured socket and vice versa.
</p>
<p>This section was generated by <strong>AutoGen</strong>,
using the <code>agtexi-cmd</code> template and the option descriptions for the <code>gnutls-cli</code> program.
This software is released under the GNU General Public License, version 3 or later.
</p>

<a name="gnutls_002dcli-usage"></a><a name="gnutls_002dcli-help_002fusage-_0028_002d_002dhelp_0029"></a>
<h4 class="subheading">gnutls-cli help/usage (<samp>--help</samp>)</h4>
<a name="index-gnutls_002dcli-help"></a>

<p>This is the automatically generated usage text for gnutls-cli.
</p>
<p>The text printed is the same whether selected with the <code>help</code> option
(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>).  <code>more-help</code> will print
the usage text by passing it through a pager program.
<code>more-help</code> is disabled on platforms without a working
<code>fork(2)</code> function.  The <code>PAGER</code> environment variable is
used to select the program, defaulting to <samp>more</samp>.  Both will exit
with a status code of 0.
</p>
<div class="example">
<pre class="example">gnutls-cli - GnuTLS client
Usage:  gnutls-cli [ -&lt;flag&gt; [&lt;val&gt;] | --&lt;name&gt;[{=| }&lt;val&gt;] ]... [hostname]

   -d, --debug=num            Enable debugging
                                - it must be in the range:
                                  0 to 9999
   -V, --verbose              More verbose output
                                - may appear multiple times
       --tofu                 Enable trust on first use authentication
                                - disabled as '--no-tofu'
       --strict-tofu          Fail to connect if a known certificate has changed
                                - disabled as '--no-strict-tofu'
       --dane                 Enable DANE certificate verification (DNSSEC)
                                - disabled as '--no-dane'
       --local-dns            Use the local DNS server for DNSSEC resolving
                                - disabled as '--no-local-dns'
       --ca-verification      Enable CA certificate verification
                                - disabled as '--no-ca-verification'
                                - enabled by default
       --ocsp                 Enable OCSP certificate verification
                                - disabled as '--no-ocsp'
   -r, --resume               Establish a session and resume
   -e, --rehandshake          Establish a session and rehandshake
   -s, --starttls             Connect, establish a plain session and start TLS
       --app-proto=str        an alias for the 'starttls-proto' option
       --starttls-proto=str   The application protocol to be used to obtain the server's certificate
(https, ftp, smtp, imap)
                                - prohibits the option 'starttls'
   -u, --udp                  Use DTLS (datagram TLS) over UDP
       --mtu=num              Set MTU for datagram TLS
                                - it must be in the range:
                                  0 to 17000
       --crlf                 Send CR LF instead of LF
       --x509fmtder           Use DER format for certificates to read from
   -f, --fingerprint          Send the openpgp fingerprint, instead of the key
       --print-cert           Print peer's certificate in PEM format
       --save-cert=str        Save the peer's certificate chain in the specified file in PEM format
       --save-ocsp=str        Save the peer's OCSP status response in the provided file
       --dh-bits=num          The minimum number of bits allowed for DH
       --priority=str         Priorities string
       --x509cafile=str       Certificate file or PKCS #11 URL to use
       --x509crlfile=file     CRL file to use
                                - file must pre-exist
       --pgpkeyfile=file      PGP Key file to use
                                - file must pre-exist
       --pgpkeyring=file      PGP Key ring file to use
                                - file must pre-exist
       --pgpcertfile=file     PGP Public Key (certificate) file to use
                                - requires the option 'pgpkeyfile'
                                - file must pre-exist
       --x509keyfile=str      X.509 key file or PKCS #11 URL to use
       --x509certfile=str     X.509 Certificate file or PKCS #11 URL to use
                                - requires the option 'x509keyfile'
       --pgpsubkey=str        PGP subkey to use (hex or auto)
       --srpusername=str      SRP username to use
       --srppasswd=str        SRP password to use
       --pskusername=str      PSK username to use
       --pskkey=str           PSK key (in hex) to use
   -p, --port=str             The port or service to connect to
       --insecure             Don't abort program if server certificate can't be validated
       --ranges               Use length-hiding padding to prevent traffic analysis
       --benchmark-ciphers    Benchmark individual ciphers
       --benchmark-tls-kx     Benchmark TLS key exchange methods
   -!, --benchmark-tls-ciphers  Benchmark TLS ciphers
   -l, --list                 Print a list of the supported algorithms and modes
                                - prohibits the option 'port'
   -&quot;, --priority-list        Print a list of the supported priority strings
   -#, --noticket             Don't allow session tickets
   -$, --srtp-profiles=str    Offer SRTP profiles
   -%, --alpn=str             Application layer protocol
                                - may appear multiple times
   -b, --heartbeat            Activate heartbeat support
   -&amp;, --recordsize=num       The maximum record size to advertize
                                - it must be in the range:
                                  0 to 4096
   -', --disable-sni          Do not send a Server Name Indication (SNI)
   -(, --disable-extensions   Disable all the TLS extensions
   -), --inline-commands      Inline commands of the form ^&lt;cmd&gt;^
   -*, --inline-commands-prefix=str Change the default delimiter for inline commands.
   -+, --provider=file        Specify the PKCS #11 provider library
                                - file must pre-exist
   -,, --fips140-mode         Reports the status of the FIPS140-2 mode in gnutls library
   -v, --version[=arg]        output version information and exit
   -h, --help                 display extended usage information and exit
   -!, --more-help            extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.
Operands and options may be intermixed.  They will be reordered.

Simple client program to set up a TLS connection to some other computer.  It
sets up a TLS connection and forwards data from the standard input to the
secured socket and vice versa.

</pre></div>

<a name="gnutls_002dcli-debug"></a><a name="debug-option-_0028_002dd_0029-6"></a>
<h4 class="subheading">debug option (-d)</h4>

<p>This is the &ldquo;enable debugging&rdquo; option.
This option takes a number argument.
Specifies the debug level.
<a name="gnutls_002dcli-tofu"></a></p><a name="tofu-option"></a>
<h4 class="subheading">tofu option</h4>

<p>This is the &ldquo;enable trust on first use authentication&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-tofu.
</li></ul>

<p>This option will, in addition to certificate authentication, perform authentication
based on previously seen public keys, a model similar to SSH authentication. Note that when tofu 
is specified (PKI) and DANE authentication will become advisory to assist the public key acceptance
process.
<a name="gnutls_002dcli-strict_002dtofu"></a></p><a name="strict_002dtofu-option"></a>
<h4 class="subheading">strict-tofu option</h4>

<p>This is the &ldquo;fail to connect if a known certificate has changed&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-strict-tofu.
</li></ul>

<p>This option will perform authentication as with option &ndash;tofu; however, while &ndash;tofu asks whether to trust a changed public key, this option will fail in case of public key changes.
<a name="gnutls_002dcli-dane"></a></p><a name="dane-option"></a>
<h4 class="subheading">dane option</h4>

<p>This is the &ldquo;enable dane certificate verification (dnssec)&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-dane.
</li></ul>

<p>This option will, in addition to certificate authentication using 
the trusted CAs, verify the server certificates using on the DANE information
available via DNSSEC.
<a name="gnutls_002dcli-local_002ddns"></a></p><a name="local_002ddns-option-1"></a>
<h4 class="subheading">local-dns option</h4>

<p>This is the &ldquo;use the local dns server for dnssec resolving&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-local-dns.
</li></ul>

<p>This option will use the local DNS server for DNSSEC.
This is disabled by default due to many servers not allowing DNSSEC.
<a name="gnutls_002dcli-ca_002dverification"></a></p><a name="ca_002dverification-option"></a>
<h4 class="subheading">ca-verification option</h4>

<p>This is the &ldquo;enable ca certificate verification&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-ca-verification.
</li><li> It is enabled by default.
</li></ul>

<p>This option can be used to enable or disable CA certificate verification. It is to be used with the &ndash;dane or &ndash;tofu options.
<a name="gnutls_002dcli-ocsp"></a></p><a name="ocsp-option"></a>
<h4 class="subheading">ocsp option</h4>

<p>This is the &ldquo;enable ocsp certificate verification&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> can be disabled with &ndash;no-ocsp.
</li></ul>

<p>This option will enable verification of the peer&rsquo;s certificate using ocsp
<a name="gnutls_002dcli-resume"></a></p><a name="resume-option-_0028_002dr_0029"></a>
<h4 class="subheading">resume option (-r)</h4>

<p>This is the &ldquo;establish a session and resume&rdquo; option.
Connect, establish a session, reconnect and resume.
<a name="gnutls_002dcli-rehandshake"></a></p><a name="rehandshake-option-_0028_002de_0029"></a>
<h4 class="subheading">rehandshake option (-e)</h4>

<p>This is the &ldquo;establish a session and rehandshake&rdquo; option.
Connect, establish a session and rehandshake immediately.
<a name="gnutls_002dcli-starttls"></a></p><a name="starttls-option-_0028_002ds_0029"></a>
<h4 class="subheading">starttls option (-s)</h4>

<p>This is the &ldquo;connect, establish a plain session and start tls&rdquo; option.
The TLS session will be initiated when EOF or a SIGALRM is received.
<a name="gnutls_002dcli-app_002dproto"></a></p><a name="app_002dproto-option-1"></a>
<h4 class="subheading">app-proto option</h4>

<p>This is an alias for the <code>starttls-proto</code> option,
see <a href="#gnutls_002dcli-starttls_002dproto">the starttls-proto option documentation</a>.
</p>
<a name="gnutls_002dcli-starttls_002dproto"></a><a name="starttls_002dproto-option-1"></a>
<h4 class="subheading">starttls-proto option</h4>

<p>This is the &ldquo;the application protocol to be used to obtain the server&rsquo;s certificate (https, ftp, smtp, imap, ldap, xmpp)&rdquo; option.
This option takes a string argument.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> must not appear in combination with any of the following options:
starttls.
</li></ul>

<p>Specify the application layer protocol for STARTTLS. If the protocol is supported, gnutls-cli will proceed to the TLS negotiation.
<a name="gnutls_002dcli-dh_002dbits"></a></p><a name="dh_002dbits-option"></a>
<h4 class="subheading">dh-bits option</h4>

<p>This is the &ldquo;the minimum number of bits allowed for dh&rdquo; option.
This option takes a number argument.
This option sets the minimum number of bits allowed for a Diffie-Hellman key exchange. You may want to lower the default value if the peer sends a weak prime and you get an connection error with unacceptable prime.
<a name="gnutls_002dcli-priority"></a></p><a name="priority-option"></a>
<h4 class="subheading">priority option</h4>

<p>This is the &ldquo;priorities string&rdquo; option.
This option takes a string argument.
TLS algorithms and protocols to enable. You can
use predefined sets of ciphersuites such as PERFORMANCE,
NORMAL, PFS, SECURE128, SECURE256. The default is NORMAL.
</p>
<p>Check  the  GnuTLS  manual  on  section  &ldquo;Priority strings&rdquo; for more
information on the allowed keywords
<a name="gnutls_002dcli-ranges"></a></p><a name="ranges-option"></a>
<h4 class="subheading">ranges option</h4>

<p>This is the &ldquo;use length-hiding padding to prevent traffic analysis&rdquo; option.
When possible (e.g., when using CBC ciphersuites), use length-hiding padding to prevent traffic analysis.
<a name="gnutls_002dcli-benchmark_002dciphers"></a></p><a name="benchmark_002dciphers-option"></a>
<h4 class="subheading">benchmark-ciphers option</h4>

<p>This is the &ldquo;benchmark individual ciphers&rdquo; option.
By default the benchmarked ciphers will utilize any capabilities of the local CPU to improve performance. To test against the raw software implementation set the environment variable GNUTLS_CPUID_OVERRIDE to 0x1.
<a name="gnutls_002dcli-benchmark_002dtls_002dciphers"></a></p><a name="benchmark_002dtls_002dciphers-option"></a>
<h4 class="subheading">benchmark-tls-ciphers option</h4>

<p>This is the &ldquo;benchmark tls ciphers&rdquo; option.
By default the benchmarked ciphers will utilize any capabilities of the local CPU to improve performance. To test against the raw software implementation set the environment variable GNUTLS_CPUID_OVERRIDE to 0x1.
<a name="gnutls_002dcli-list"></a></p><a name="list-option-_0028_002dl_0029"></a>
<h4 class="subheading">list option (-l)</h4>

<p>This is the &ldquo;print a list of the supported algorithms and modes&rdquo; option.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> must not appear in combination with any of the following options:
port.
</li></ul>

<p>Print a list of the supported algorithms and modes. If a priority string is given then only the enabled ciphersuites are shown.
<a name="gnutls_002dcli-priority_002dlist"></a></p><a name="priority_002dlist-option"></a>
<h4 class="subheading">priority-list option</h4>

<p>This is the &ldquo;print a list of the supported priority strings&rdquo; option.
Print a list of the supported priority strings. The ciphersuites corresponding to each priority string can be examined using -l -p.
<a name="gnutls_002dcli-alpn"></a></p><a name="alpn-option"></a>
<h4 class="subheading">alpn option</h4>

<p>This is the &ldquo;application layer protocol&rdquo; option.
This option takes a string argument.
</p>
<p>This option has some usage constraints.  It:
</p><ul>
<li> may appear an unlimited number of times.
</li></ul>

<p>This option will set and enable the Application Layer Protocol Negotiation  (ALPN) in the TLS protocol.
<a name="gnutls_002dcli-disable_002dextensions"></a></p><a name="disable_002dextensions-option"></a>
<h4 class="subheading">disable-extensions option</h4>

<p>This is the &ldquo;disable all the tls extensions&rdquo; option.
This option disables all TLS extensions. Deprecated option. Use the priority string.
<a name="gnutls_002dcli-inline_002dcommands"></a></p><a name="inline_002dcommands-option"></a>
<h4 class="subheading">inline-commands option</h4>

<p>This is the &ldquo;inline commands of the form ^&lt;cmd&gt;^&rdquo; option.
Enable inline commands of the form ^&lt;cmd&gt;^. The inline commands are expected to be in a line by themselves. The available commands are: resume and renegotiate.
<a name="gnutls_002dcli-inline_002dcommands_002dprefix"></a></p><a name="inline_002dcommands_002dprefix-option"></a>
<h4 class="subheading">inline-commands-prefix option</h4>

<p>This is the &ldquo;change the default delimiter for inline commands.&rdquo; option.
This option takes a string argument.
Change the default delimiter (^) used for inline commands. The delimiter is expected to be a single US-ASCII character (octets 0 - 127). This option is only relevant if inline commands are enabled via the inline-commands option
<a name="gnutls_002dcli-provider"></a></p><a name="provider-option-1"></a>
<h4 class="subheading">provider option</h4>

<p>This is the &ldquo;specify the pkcs #11 provider library&rdquo; option.
This option takes a file argument.
This will override the default options in /etc/gnutls/pkcs11.conf
<a name="gnutls_002dcli-exit-status"></a></p><a name="gnutls_002dcli-exit-status-1"></a>
<h4 class="subheading">gnutls-cli exit status</h4>

<p>One of the following exit values will be returned:
</p><dl compact="compact">
<dt>&lsquo;<samp>0 (EXIT_SUCCESS)</samp>&rsquo;</dt>
<dd><p>Successful program execution.
</p></dd>
<dt>&lsquo;<samp>1 (EXIT_FAILURE)</samp>&rsquo;</dt>
<dd><p>The operation failed or the command syntax was not valid.
</p></dd>
</dl>
<a name="gnutls_002dcli-See-Also"></a><a name="gnutls_002dcli-See-Also-1"></a>
<h4 class="subheading">gnutls-cli See Also</h4>
<p>gnutls-cli-debug(1), gnutls-serv(1)
<a name="gnutls_002dcli-Examples"></a></p><a name="gnutls_002dcli-Examples-1"></a>
<h4 class="subheading">gnutls-cli Examples</h4>
<a name="Connecting-using-PSK-authentication"></a>
<h4 class="subheading">Connecting using PSK authentication</h4>
<p>To connect to a server using PSK authentication, you need to enable the choice of PSK by using a cipher priority parameter such as in the example below. 
</p><div class="example">
<pre class="example">$ ./gnutls-cli -p 5556 localhost --pskusername psk_identity \
    --pskkey 88f3824b3e5659f52d00e959bacab954b6540344 \
    --priority NORMAL:-KX-ALL:+ECDHE-PSK:+DHE-PSK:+PSK
Resolving 'localhost'...
Connecting to '127.0.0.1:5556'...
- PSK authentication.
- Version: TLS1.1
- Key Exchange: PSK
- Cipher: AES-128-CBC
- MAC: SHA1
- Compression: NULL
- Handshake was completed
    
- Simple Client Mode:
</pre></div>
<p>By keeping the &ndash;pskusername parameter and removing the &ndash;pskkey parameter, it will query only for the password during the handshake. 
</p>
<a name="Listing-ciphersuites-in-a-priority-string"></a>
<h4 class="subheading">Listing ciphersuites in a priority string</h4>
<p>To list the ciphersuites in a priority string:
</p><div class="example">
<pre class="example">$ ./gnutls-cli --priority SECURE192 -l
Cipher suites for SECURE192
TLS_ECDHE_ECDSA_AES_256_CBC_SHA384         0xc0, 0x24	TLS1.2
TLS_ECDHE_ECDSA_AES_256_GCM_SHA384         0xc0, 0x2e	TLS1.2
TLS_ECDHE_RSA_AES_256_GCM_SHA384           0xc0, 0x30	TLS1.2
TLS_DHE_RSA_AES_256_CBC_SHA256             0x00, 0x6b	TLS1.2
TLS_DHE_DSS_AES_256_CBC_SHA256             0x00, 0x6a	TLS1.2
TLS_RSA_AES_256_CBC_SHA256                 0x00, 0x3d	TLS1.2

Certificate types: CTYPE-X.509
Protocols: VERS-TLS1.2, VERS-TLS1.1, VERS-TLS1.0, VERS-SSL3.0, VERS-DTLS1.0
Compression: COMP-NULL
Elliptic curves: CURVE-SECP384R1, CURVE-SECP521R1
PK-signatures: SIGN-RSA-SHA384, SIGN-ECDSA-SHA384, SIGN-RSA-SHA512, SIGN-ECDSA-SHA512
</pre></div>

<a name="Connecting-using-a-PKCS-_002311-token"></a>
<h4 class="subheading">Connecting using a PKCS #11 token</h4>
<p>To connect to a server using a certificate and a private key present in a PKCS #11 token you 
need to substitute the PKCS 11 URLs in the x509certfile and x509keyfile parameters.
</p>
<p>Those can be found using &quot;p11tool &ndash;list-tokens&quot; and then listing all the objects in the
needed token, and using the appropriate.
</p><div class="example">
<pre class="example">$ p11tool --list-tokens

Token 0:
URL: pkcs11:model=PKCS15;manufacturer=MyMan;serial=1234;token=Test
Label: Test
Manufacturer: EnterSafe
Model: PKCS15
Serial: 1234

$ p11tool --login --list-certs &quot;pkcs11:model=PKCS15;manufacturer=MyMan;serial=1234;token=Test&quot;

Object 0:
URL: pkcs11:model=PKCS15;manufacturer=MyMan;serial=1234;token=Test;object=client;type=cert
Type: X.509 Certificate
Label: client
ID: 2a:97:0d:58:d1:51:3c:23:07:ae:4e:0d:72:26:03:7d:99:06:02:6a

$ MYCERT=&quot;pkcs11:model=PKCS15;manufacturer=MyMan;serial=1234;token=Test;object=client;type=cert&quot;
$ MYKEY=&quot;pkcs11:model=PKCS15;manufacturer=MyMan;serial=1234;token=Test;object=client;type=private&quot;
$ export MYCERT MYKEY

$ gnutls-cli www.example.com --x509keyfile $MYKEY --x509certfile $MYCERT
</pre></div>
<p>Notice that the private key only differs from the certificate in the type.
</p><hr>
<a name="gnutls_002dserv-Invocation"></a>
<div class="header">
<p>
Next: <a href="#gnutls_002dcli_002ddebug-Invocation" accesskey="n" rel="next">gnutls-cli-debug Invocation</a>, Previous: <a href="#gnutls_002dcli-Invocation" accesskey="p" rel="prev">gnutls-cli Invocation</a>, Up: <a href="#Other-included-programs" accesskey="u" rel="up">Other included programs</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Invoking-gnutls_002dserv"></a>
<h3 class="section">9.2 Invoking gnutls-serv</h3>
<a name="index-gnutls_002dserv"></a>


<p>Server program that listens to incoming TLS connections.
</p>
<p>This section was generated by <strong>AutoGen</strong>,
using the <code>agtexi-cmd</code> template and the option descriptions for the <code>gnutls-serv</code> program.
This software is released under the GNU General Public License, version 3 or later.
</p>

<a name="gnutls_002dserv-usage"></a><a name="gnutls_002dserv-help_002fusage-_0028_002d_002dhelp_0029"></a>
<h4 class="subheading">gnutls-serv help/usage (<samp>--help</samp>)</h4>
<a name="index-gnutls_002dserv-help"></a>

<p>This is the automatically generated usage text for gnutls-serv.
</p>
<p>The text printed is the same whether selected with the <code>help</code> option
(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>).  <code>more-help</code> will print
the usage text by passing it through a pager program.
<code>more-help</code> is disabled on platforms without a working
<code>fork(2)</code> function.  The <code>PAGER</code> environment variable is
used to select the program, defaulting to <samp>more</samp>.  Both will exit
with a status code of 0.
</p>
<div class="example">
<pre class="example">gnutls-serv - GnuTLS server
Usage:  gnutls-serv [ -&lt;flag&gt; [&lt;val&gt;] | --&lt;name&gt;[{=| }&lt;val&gt;] ]...

   -d, --debug=num            Enable debugging
                                - it must be in the range:
                                  0 to 9999
       --noticket             Don't accept session tickets
   -g, --generate             Generate Diffie-Hellman and RSA-export parameters
   -q, --quiet                Suppress some messages
       --nodb                 Do not use a resumption database
       --http                 Act as an HTTP server
       --echo                 Act as an Echo server
   -u, --udp                  Use DTLS (datagram TLS) over UDP
       --mtu=num              Set MTU for datagram TLS
                                - it must be in the range:
                                  0 to 17000
       --srtp-profiles=str    Offer SRTP profiles
   -a, --disable-client-cert  Do not request a client certificate
   -r, --require-client-cert  Require a client certificate
       --verify-client-cert   If a client certificate is sent then verify it.
   -b, --heartbeat            Activate heartbeat support
       --x509fmtder           Use DER format for certificates to read from
       --priority=str         Priorities string
       --dhparams=file        DH params file to use
                                - file must pre-exist
       --x509cafile=str       Certificate file or PKCS #11 URL to use
       --x509crlfile=file     CRL file to use
                                - file must pre-exist
       --pgpkeyfile=file      PGP Key file to use
                                - file must pre-exist
       --pgpkeyring=file      PGP Key ring file to use
                                - file must pre-exist
       --pgpcertfile=file     PGP Public Key (certificate) file to use
                                - file must pre-exist
       --x509keyfile=str      X.509 key file or PKCS #11 URL to use
       --x509certfile=str     X.509 Certificate file or PKCS #11 URL to use
       --x509dsakeyfile=str   Alternative X.509 key file or PKCS #11 URL to use
       --x509dsacertfile=str  Alternative X.509 Certificate file or PKCS #11 URL to use
       --x509ecckeyfile=str   Alternative X.509 key file or PKCS #11 URL to use
       --x509ecccertfile=str  Alternative X.509 Certificate file or PKCS #11 URL to use
       --pgpsubkey=str        PGP subkey to use (hex or auto)
       --srppasswd=file       SRP password file to use
                                - file must pre-exist
       --srppasswdconf=file   SRP password configuration file to use
                                - file must pre-exist
       --pskpasswd=file       PSK password file to use
                                - file must pre-exist
       --pskhint=str          PSK identity hint to use
       --ocsp-response=file   The OCSP response to send to client
                                - file must pre-exist
   -p, --port=num             The port to connect to
   -l, --list                 Print a list of the supported algorithms and modes
       --provider=file        Specify the PKCS #11 provider library
                                - file must pre-exist
   -v, --version[=arg]        output version information and exit
   -h, --help                 display extended usage information and exit
   -!, --more-help            extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.

Server program that listens to incoming TLS connections.

</pre></div>

<a name="gnutls_002dserv-debug"></a><a name="debug-option-_0028_002dd_0029-7"></a>
<h4 class="subheading">debug option (-d)</h4>

<p>This is the &ldquo;enable debugging&rdquo; option.
This option takes a number argument.
Specifies the debug level.
<a name="gnutls_002dserv-verify_002dclient_002dcert"></a></p><a name="verify_002dclient_002dcert-option"></a>
<h4 class="subheading">verify-client-cert option</h4>

<p>This is the &ldquo;if a client certificate is sent then verify it.&rdquo; option.
Do not require, but if a client certificate is sent then verify it and close the connection if invalid.
<a name="gnutls_002dserv-heartbeat"></a></p><a name="heartbeat-option-_0028_002db_0029"></a>
<h4 class="subheading">heartbeat option (-b)</h4>

<p>This is the &ldquo;activate heartbeat support&rdquo; option.
Regularly ping client via heartbeat extension messages
<a name="gnutls_002dserv-priority"></a></p><a name="priority-option-1"></a>
<h4 class="subheading">priority option</h4>

<p>This is the &ldquo;priorities string&rdquo; option.
This option takes a string argument.
TLS algorithms and protocols to enable. You can
use predefined sets of ciphersuites such as PERFORMANCE,
NORMAL, SECURE128, SECURE256. The default is NORMAL.
</p>
<p>Check  the  GnuTLS  manual  on  section  &ldquo;Priority strings&rdquo; for more
information on allowed keywords
<a name="gnutls_002dserv-ocsp_002dresponse"></a></p><a name="ocsp_002dresponse-option"></a>
<h4 class="subheading">ocsp-response option</h4>

<p>This is the &ldquo;the ocsp response to send to client&rdquo; option.
This option takes a file argument.
If the client requested an OCSP response, return data from this file to the client.
<a name="gnutls_002dserv-list"></a></p><a name="list-option-_0028_002dl_0029-1"></a>
<h4 class="subheading">list option (-l)</h4>

<p>This is the &ldquo;print a list of the supported algorithms and modes&rdquo; option.
Print a list of the supported algorithms and modes. If a priority string is given then only the enabled ciphersuites are shown.
<a name="gnutls_002dserv-provider"></a></p><a name="provider-option-2"></a>
<h4 class="subheading">provider option</h4>

<p>This is the &ldquo;specify the pkcs #11 provider library&rdquo; option.
This option takes a file argument.
This will override the default options in /etc/gnutls/pkcs11.conf
<a name="gnutls_002dserv-exit-status"></a></p><a name="gnutls_002dserv-exit-status-1"></a>
<h4 class="subheading">gnutls-serv exit status</h4>

<p>One of the following exit values will be returned:
</p><dl compact="compact">
<dt>&lsquo;<samp>0 (EXIT_SUCCESS)</samp>&rsquo;</dt>
<dd><p>Successful program execution.
</p></dd>
<dt>&lsquo;<samp>1 (EXIT_FAILURE)</samp>&rsquo;</dt>
<dd><p>The operation failed or the command syntax was not valid.
</p></dd>
</dl>
<a name="gnutls_002dserv-See-Also"></a><a name="gnutls_002dserv-See-Also-1"></a>
<h4 class="subheading">gnutls-serv See Also</h4>
<p>gnutls-cli-debug(1), gnutls-cli(1)
<a name="gnutls_002dserv-Examples"></a></p><a name="gnutls_002dserv-Examples-1"></a>
<h4 class="subheading">gnutls-serv Examples</h4>
<p>Running your own TLS server based on GnuTLS can be useful when
debugging clients and/or GnuTLS itself.  This section describes how to
use <code>gnutls-serv</code> as a simple HTTPS server.
</p>
<p>The most basic server can be started as:
</p>
<div class="example">
<pre class="example">gnutls-serv --http --priority &quot;NORMAL:+ANON-ECDH:+ANON-DH&quot;
</pre></div>

<p>It will only support anonymous ciphersuites, which many TLS clients
refuse to use.
</p>
<p>The next step is to add support for X.509.  First we generate a CA:
</p>
<div class="example">
<pre class="example">$ certtool --generate-privkey &gt; x509-ca-key.pem
$ echo 'cn = GnuTLS test CA' &gt; ca.tmpl
$ echo 'ca' &gt;&gt; ca.tmpl
$ echo 'cert_signing_key' &gt;&gt; ca.tmpl
$ certtool --generate-self-signed --load-privkey x509-ca-key.pem \
  --template ca.tmpl --outfile x509-ca.pem
...
</pre></div>

<p>Then generate a server certificate.  Remember to change the dns_name
value to the name of your server host, or skip that command to avoid
the field.
</p>
<div class="example">
<pre class="example">$ certtool --generate-privkey &gt; x509-server-key.pem
$ echo 'organization = GnuTLS test server' &gt; server.tmpl
$ echo 'cn = test.gnutls.org' &gt;&gt; server.tmpl
$ echo 'tls_www_server' &gt;&gt; server.tmpl
$ echo 'encryption_key' &gt;&gt; server.tmpl
$ echo 'signing_key' &gt;&gt; server.tmpl
$ echo 'dns_name = test.gnutls.org' &gt;&gt; server.tmpl
$ certtool --generate-certificate --load-privkey x509-server-key.pem \
  --load-ca-certificate x509-ca.pem --load-ca-privkey x509-ca-key.pem \
  --template server.tmpl --outfile x509-server.pem
...
</pre></div>

<p>For use in the client, you may want to generate a client certificate
as well.
</p>
<div class="example">
<pre class="example">$ certtool --generate-privkey &gt; x509-client-key.pem
$ echo 'cn = GnuTLS test client' &gt; client.tmpl
$ echo 'tls_www_client' &gt;&gt; client.tmpl
$ echo 'encryption_key' &gt;&gt; client.tmpl
$ echo 'signing_key' &gt;&gt; client.tmpl
$ certtool --generate-certificate --load-privkey x509-client-key.pem \
  --load-ca-certificate x509-ca.pem --load-ca-privkey x509-ca-key.pem \
  --template client.tmpl --outfile x509-client.pem
...
</pre></div>

<p>To be able to import the client key/certificate into some
applications, you will need to convert them into a PKCS#12 structure.
This also encrypts the security sensitive key with a password.
</p>
<div class="example">
<pre class="example">$ certtool --to-p12 --load-ca-certificate x509-ca.pem \
  --load-privkey x509-client-key.pem --load-certificate x509-client.pem \
  --outder --outfile x509-client.p12
</pre></div>

<p>For icing, we&rsquo;ll create a proxy certificate for the client too.
</p>
<div class="example">
<pre class="example">$ certtool --generate-privkey &gt; x509-proxy-key.pem
$ echo 'cn = GnuTLS test client proxy' &gt; proxy.tmpl
$ certtool --generate-proxy --load-privkey x509-proxy-key.pem \
  --load-ca-certificate x509-client.pem --load-ca-privkey x509-client-key.pem \
  --load-certificate x509-client.pem --template proxy.tmpl \
  --outfile x509-proxy.pem
...
</pre></div>

<p>Then start the server again:
</p>
<div class="example">
<pre class="example">$ gnutls-serv --http \
            --x509cafile x509-ca.pem \
            --x509keyfile x509-server-key.pem \
            --x509certfile x509-server.pem
</pre></div>

<p>Try connecting to the server using your web browser.  Note that the
server listens to port 5556 by default.
</p>
<p>While you are at it, to allow connections using DSA, you can also
create a DSA key and certificate for the server.  These credentials
will be used in the final example below.
</p>
<div class="example">
<pre class="example">$ certtool --generate-privkey --dsa &gt; x509-server-key-dsa.pem
$ certtool --generate-certificate --load-privkey x509-server-key-dsa.pem \
  --load-ca-certificate x509-ca.pem --load-ca-privkey x509-ca-key.pem \
  --template server.tmpl --outfile x509-server-dsa.pem
...
</pre></div>

<p>The next step is to create OpenPGP credentials for the server.
</p>
<div class="example">
<pre class="example">gpg --gen-key
...enter whatever details you want, use 'test.gnutls.org' as name...
</pre></div>

<p>Make a note of the OpenPGP key identifier of the newly generated key,
here it was <code>5D1D14D8</code>.  You will need to export the key for
GnuTLS to be able to use it.
</p>
<div class="example">
<pre class="example">gpg -a --export 5D1D14D8 &gt; openpgp-server.txt
gpg --export 5D1D14D8 &gt; openpgp-server.bin
gpg --export-secret-keys 5D1D14D8 &gt; openpgp-server-key.bin
gpg -a --export-secret-keys 5D1D14D8 &gt; openpgp-server-key.txt
</pre></div>

<p>Let&rsquo;s start the server with support for OpenPGP credentials:
</p>
<div class="example">
<pre class="example">gnutls-serv --http --priority NORMAL:+CTYPE-OPENPGP \
            --pgpkeyfile openpgp-server-key.txt \
            --pgpcertfile openpgp-server.txt
</pre></div>

<p>The next step is to add support for SRP authentication. This requires
an SRP password file created with <code>srptool</code>.
To start the server with SRP support:
</p>
<div class="example">
<pre class="example">gnutls-serv --http --priority NORMAL:+SRP-RSA:+SRP \
            --srppasswdconf srp-tpasswd.conf \
            --srppasswd srp-passwd.txt
</pre></div>

<p>Let&rsquo;s also start a server with support for PSK. This would require
a password file created with <code>psktool</code>.
</p>
<div class="example">
<pre class="example">gnutls-serv --http --priority NORMAL:+ECDHE-PSK:+PSK \
            --pskpasswd psk-passwd.txt
</pre></div>

<p>Finally, we start the server with all the earlier parameters and you
get this command:
</p>
<div class="example">
<pre class="example">gnutls-serv --http --priority NORMAL:+PSK:+SRP:+CTYPE-OPENPGP \
            --x509cafile x509-ca.pem \
            --x509keyfile x509-server-key.pem \
            --x509certfile x509-server.pem \
            --x509dsakeyfile x509-server-key-dsa.pem \
            --x509dsacertfile x509-server-dsa.pem \
            --pgpkeyfile openpgp-server-key.txt \
            --pgpcertfile openpgp-server.txt \
            --srppasswdconf srp-tpasswd.conf \
            --srppasswd srp-passwd.txt \
            --pskpasswd psk-passwd.txt
</pre></div>
<hr>
<a name="gnutls_002dcli_002ddebug-Invocation"></a>
<div class="header">
<p>
Previous: <a href="#gnutls_002dserv-Invocation" accesskey="p" rel="prev">gnutls-serv Invocation</a>, Up: <a href="#Other-included-programs" accesskey="u" rel="up">Other included programs</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Invoking-gnutls_002dcli_002ddebug"></a>
<h3 class="section">9.3 Invoking gnutls-cli-debug</h3>
<a name="index-gnutls_002dcli_002ddebug"></a>


<p>TLS debug client. It sets up multiple TLS connections to 
a server and queries its capabilities. It was created to assist in debugging 
GnuTLS, but it might be useful to extract a TLS server&rsquo;s capabilities.
It connects to a TLS server, performs tests and print the server&rsquo;s 
capabilities. If called with the &lsquo;-v&rsquo; parameter more checks will be performed.
Can be used to check for servers with special needs or bugs.
</p>
<p>This section was generated by <strong>AutoGen</strong>,
using the <code>agtexi-cmd</code> template and the option descriptions for the <code>gnutls-cli-debug</code> program.
This software is released under the GNU General Public License, version 3 or later.
</p>

<a name="gnutls_002dcli_002ddebug-usage"></a><a name="gnutls_002dcli_002ddebug-help_002fusage-_0028_002d_002dhelp_0029"></a>
<h4 class="subheading">gnutls-cli-debug help/usage (<samp>--help</samp>)</h4>
<a name="index-gnutls_002dcli_002ddebug-help"></a>

<p>This is the automatically generated usage text for gnutls-cli-debug.
</p>
<p>The text printed is the same whether selected with the <code>help</code> option
(<samp>--help</samp>) or the <code>more-help</code> option (<samp>--more-help</samp>).  <code>more-help</code> will print
the usage text by passing it through a pager program.
<code>more-help</code> is disabled on platforms without a working
<code>fork(2)</code> function.  The <code>PAGER</code> environment variable is
used to select the program, defaulting to <samp>more</samp>.  Both will exit
with a status code of 0.
</p>
<div class="example">
<pre class="example">gnutls-cli-debug - GnuTLS debug client
Usage:  gnutls-cli-debug [ -&lt;flag&gt; [&lt;val&gt;] | --&lt;name&gt;[{=| }&lt;val&gt;] ]... 

   -d, --debug=num            Enable debugging
                                - it must be in the range:
                                  0 to 9999
   -V, --verbose              More verbose output
                                - may appear multiple times
   -p, --port=num             The port to connect to
                                - it must be in the range:
                                  0 to 65536
       --app-proto=str        an alias for the 'starttls-proto' option
       --starttls-proto=str   The application protocol to be used to obtain the server's certificate
(https, ftp, smtp, imap, ldap, xmpp)
   -v, --version[=arg]        output version information and exit
   -h, --help                 display extended usage information and exit
   -!, --more-help            extended usage information passed thru pager

Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.
Operands and options may be intermixed.  They will be reordered.

TLS debug client.  It sets up multiple TLS connections to a server and
queries its capabilities.  It was created to assist in debugging GnuTLS,
but it might be useful to extract a TLS server's capabilities.  It connects
to a TLS server, performs tests and print the server's capabilities.  If
called with the `-v' parameter more checks will be performed.  Can be used
to check for servers with special needs or bugs.

</pre></div>

<a name="gnutls_002dcli_002ddebug-debug"></a><a name="debug-option-_0028_002dd_0029-8"></a>
<h4 class="subheading">debug option (-d)</h4>

<p>This is the &ldquo;enable debugging&rdquo; option.
This option takes a number argument.
Specifies the debug level.
<a name="gnutls_002dcli_002ddebug-app_002dproto"></a></p><a name="app_002dproto-option-2"></a>
<h4 class="subheading">app-proto option</h4>

<p>This is an alias for the <code>starttls-proto</code> option,
see <a href="#gnutls_002dcli_002ddebug-starttls_002dproto">the starttls-proto option documentation</a>.
</p>
<a name="gnutls_002dcli_002ddebug-starttls_002dproto"></a><a name="starttls_002dproto-option-2"></a>
<h4 class="subheading">starttls-proto option</h4>

<p>This is the &ldquo;the application protocol to be used to obtain the server&rsquo;s certificate (https, ftp, smtp, imap, ldap, xmpp)&rdquo; option.
This option takes a string argument.
Specify the application layer protocol for STARTTLS. If the protocol is supported, gnutls-cli will proceed to the TLS negotiation.
<a name="gnutls_002dcli_002ddebug-exit-status"></a></p><a name="gnutls_002dcli_002ddebug-exit-status-1"></a>
<h4 class="subheading">gnutls-cli-debug exit status</h4>

<p>One of the following exit values will be returned:
</p><dl compact="compact">
<dt>&lsquo;<samp>0 (EXIT_SUCCESS)</samp>&rsquo;</dt>
<dd><p>Successful program execution.
</p></dd>
<dt>&lsquo;<samp>1 (EXIT_FAILURE)</samp>&rsquo;</dt>
<dd><p>The operation failed or the command syntax was not valid.
</p></dd>
</dl>
<a name="gnutls_002dcli_002ddebug-See-Also"></a><a name="gnutls_002dcli_002ddebug-See-Also-1"></a>
<h4 class="subheading">gnutls-cli-debug See Also</h4>
<p>gnutls-cli(1), gnutls-serv(1)
<a name="gnutls_002dcli_002ddebug-Examples"></a></p><a name="gnutls_002dcli_002ddebug-Examples-1"></a>
<h4 class="subheading">gnutls-cli-debug Examples</h4>
<div class="example">
<pre class="example">$ ../src/gnutls-cli-debug localhost
GnuTLS debug client 3.5.0
Checking localhost:443
                             for SSL 3.0 (RFC6101) support... yes
                        whether we need to disable TLS 1.2... no
                        whether we need to disable TLS 1.1... no
                        whether we need to disable TLS 1.0... no
                        whether %NO_EXTENSIONS is required... no
                               whether %COMPAT is required... no
                             for TLS 1.0 (RFC2246) support... yes
                             for TLS 1.1 (RFC4346) support... yes
                             for TLS 1.2 (RFC5246) support... yes
                                  fallback from TLS 1.6 to... TLS1.2
                        for RFC7507 inappropriate fallback... yes
                                     for HTTPS server name... Local
                               for certificate chain order... sorted
                  for safe renegotiation (RFC5746) support... yes
                     for Safe renegotiation support (SCSV)... no
                    for encrypt-then-MAC (RFC7366) support... no
                   for ext master secret (RFC7627) support... no
                           for heartbeat (RFC6520) support... no
                       for version rollback bug in RSA PMS... dunno
                  for version rollback bug in Client Hello... no
            whether the server ignores the RSA PMS version... yes
whether small records (512 bytes) are tolerated on handshake... yes
    whether cipher suites not in SSL 3.0 spec are accepted... yes
whether a bogus TLS record version in the client hello is accepted... yes
         whether the server understands TLS closure alerts... partially
            whether the server supports session resumption... yes
                      for anonymous authentication support... no
                      for ephemeral Diffie-Hellman support... no
                   for ephemeral EC Diffie-Hellman support... yes
                    ephemeral EC Diffie-Hellman group info... SECP256R1
                  for AES-128-GCM cipher (RFC5288) support... yes
                  for AES-128-CCM cipher (RFC6655) support... no
                for AES-128-CCM-8 cipher (RFC6655) support... no
                  for AES-128-CBC cipher (RFC3268) support... yes
             for CAMELLIA-128-GCM cipher (RFC6367) support... no
             for CAMELLIA-128-CBC cipher (RFC5932) support... no
                     for 3DES-CBC cipher (RFC2246) support... yes
                  for ARCFOUR 128 cipher (RFC2246) support... yes
                                       for MD5 MAC support... yes
                                      for SHA1 MAC support... yes
                                    for SHA256 MAC support... yes
                              for ZLIB compression support... no
                     for max record size (RFC6066) support... no
                for OCSP status response (RFC6066) support... no
              for OpenPGP authentication (RFC6091) support... no
</pre></div>

<hr>
<a name="Internal-architecture-of-GnuTLS"></a>
<div class="header">
<p>
Next: <a href="#Upgrading-from-previous-versions" accesskey="n" rel="next">Upgrading from previous versions</a>, Previous: <a href="#Other-included-programs" accesskey="p" rel="prev">Other included programs</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Internal-Architecture-of-GnuTLS"></a>
<h2 class="chapter">10 Internal Architecture of GnuTLS</h2>
<a name="index-internal-architecture"></a>

<p>This chapter is to give a brief description of the
way <acronym>GnuTLS</acronym> works. The focus is to give an idea
to potential developers and those who want to know what
happens inside the black box.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#The-TLS-Protocol" accesskey="1">The TLS Protocol</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#TLS-Handshake-Protocol" accesskey="2">TLS Handshake Protocol</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#TLS-Authentication-Methods" accesskey="3">TLS Authentication Methods</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#TLS-Extension-Handling" accesskey="4">TLS Extension Handling</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Cryptographic-Backend" accesskey="5">Cryptographic Backend</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="The-TLS-Protocol"></a>
<div class="header">
<p>
Next: <a href="#TLS-Handshake-Protocol" accesskey="n" rel="next">TLS Handshake Protocol</a>, Up: <a href="#Internal-architecture-of-GnuTLS" accesskey="u" rel="up">Internal architecture of GnuTLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="The-TLS-Protocol-1"></a>
<h3 class="section">10.1 The TLS Protocol</h3>
<p>The main use case for the TLS protocol is shown in <a href="#fig_002dclient_002dserver">Figure 10.1</a>.
A user of a library implementing the protocol expects no less than this functionality,
i.e., to be able to set parameters such as the accepted security level, perform a
negotiation with the peer and be able to exchange data.
</p>
<div class="float"><a name="fig_002dclient_002dserver"></a>
<img src="gnutls-client-server-use-case.png" alt="gnutls-client-server-use-case">

<div class="float-caption"><p><strong>Figure 10.1: </strong>TLS protocol use case.</p></div></div>
<hr>
<a name="TLS-Handshake-Protocol"></a>
<div class="header">
<p>
Next: <a href="#TLS-Authentication-Methods" accesskey="n" rel="next">TLS Authentication Methods</a>, Previous: <a href="#The-TLS-Protocol" accesskey="p" rel="prev">The TLS Protocol</a>, Up: <a href="#Internal-architecture-of-GnuTLS" accesskey="u" rel="up">Internal architecture of GnuTLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="TLS-Handshake-Protocol-1"></a>
<h3 class="section">10.2 TLS Handshake Protocol</h3>
<p>The <acronym>GnuTLS</acronym> handshake protocol is implemented as a state
machine that waits for input or returns immediately when the non-blocking
transport layer functions are used. The main idea is shown in <a href="#fig_002dgnutls_002dhandshake">Figure 10.2</a>.
</p>
<div class="float"><a name="fig_002dgnutls_002dhandshake"></a>
<img src="gnutls-handshake-state.png" alt="gnutls-handshake-state">

<div class="float-caption"><p><strong>Figure 10.2: </strong>GnuTLS handshake state machine.</p></div></div>
<p>Also the way the input is processed varies per ciphersuite. Several 
implementations of the internal handlers are available and 
<a href="#gnutls_005fhandshake">gnutls_handshake</a> only multiplexes the input to the appropriate 
handler. For example a <acronym>PSK</acronym> ciphersuite has a different 
implementation of the <code>process_client_key_exchange</code> than a
certificate ciphersuite. We illustrate the idea in <a href="#fig_002dgnutls_002dhandshake_002dsequence">Figure 10.3</a>.
</p>
<div class="float"><a name="fig_002dgnutls_002dhandshake_002dsequence"></a>
<img src="gnutls-handshake-sequence.png" alt="gnutls-handshake-sequence">

<div class="float-caption"><p><strong>Figure 10.3: </strong>GnuTLS handshake process sequence.</p></div></div>
<hr>
<a name="TLS-Authentication-Methods"></a>
<div class="header">
<p>
Next: <a href="#TLS-Extension-Handling" accesskey="n" rel="next">TLS Extension Handling</a>, Previous: <a href="#TLS-Handshake-Protocol" accesskey="p" rel="prev">TLS Handshake Protocol</a>, Up: <a href="#Internal-architecture-of-GnuTLS" accesskey="u" rel="up">Internal architecture of GnuTLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="TLS-Authentication-Methods-1"></a>
<h3 class="section">10.3 TLS Authentication Methods</h3>
<p>In <acronym>GnuTLS</acronym> authentication methods can be implemented quite
easily.  Since the required changes to add a new authentication method
affect only the handshake protocol, a simple interface is used. An
authentication method needs to implement the functions shown below.
</p>
<pre class="verbatim">typedef struct 
{
  const char *name;
  int (*gnutls_generate_server_certificate) (gnutls_session_t, gnutls_buffer_st*);
  int (*gnutls_generate_client_certificate) (gnutls_session_t, gnutls_buffer_st*);
  int (*gnutls_generate_server_kx) (gnutls_session_t, gnutls_buffer_st*);
  int (*gnutls_generate_client_kx) (gnutls_session_t, gnutls_buffer_st*);
  int (*gnutls_generate_client_cert_vrfy) (gnutls_session_t, gnutls_buffer_st *);
  int (*gnutls_generate_server_certificate_request) (gnutls_session_t,
                                                     gnutls_buffer_st *);

  int (*gnutls_process_server_certificate) (gnutls_session_t, opaque *,
                                            size_t);
  int (*gnutls_process_client_certificate) (gnutls_session_t, opaque *,
                                            size_t);
  int (*gnutls_process_server_kx) (gnutls_session_t, opaque *, size_t);
  int (*gnutls_process_client_kx) (gnutls_session_t, opaque *, size_t);
  int (*gnutls_process_client_cert_vrfy) (gnutls_session_t, opaque *, size_t);
  int (*gnutls_process_server_certificate_request) (gnutls_session_t,
                                                    opaque *, size_t);
} mod_auth_st;
</pre>
<p>Those functions are responsible for the
interpretation of the handshake protocol messages. It is common for such
functions to read data from one or more <code>credentials_t</code>
structures<a name="DOCF20" href="#FOOT20"><sup>20</sup></a> and write data,
such as certificates, usernames etc. to <code>auth_info_t</code> structures.
</p>

<p>Simple examples of existing authentication methods can be seen in
<code>auth/psk.c</code> for PSK ciphersuites and <code>auth/srp.c</code> for SRP
ciphersuites. After implementing these functions the structure holding
its pointers has to be registered in <code>gnutls_algorithms.c</code> in the
<code>_gnutls_kx_algorithms</code> structure.
</p>
<hr>
<a name="TLS-Extension-Handling"></a>
<div class="header">
<p>
Next: <a href="#Cryptographic-Backend" accesskey="n" rel="next">Cryptographic Backend</a>, Previous: <a href="#TLS-Authentication-Methods" accesskey="p" rel="prev">TLS Authentication Methods</a>, Up: <a href="#Internal-architecture-of-GnuTLS" accesskey="u" rel="up">Internal architecture of GnuTLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="TLS-Extension-Handling-1"></a>
<h3 class="section">10.4 TLS Extension Handling</h3>
<p>As with authentication methods, the TLS extensions handlers can be
implemented using the interface shown below.
</p>
<pre class="verbatim">typedef int (*gnutls_ext_recv_func) (gnutls_session_t session,
                                     const unsigned char *data, size_t len);
typedef int (*gnutls_ext_send_func) (gnutls_session_t session,
                                     gnutls_buffer_st *extdata);
</pre>
<p>Here there are two functions, one for receiving the extension data
and one for sending. These functions have to check internally whether
they operate in client or server side. 
</p>
<p>A simple example of an extension handler can be seen in
<code>ext/srp.c</code> in GnuTLS&rsquo; source code. After implementing these functions, 
together with the extension number they handle, they have to be registered 
using <code>_gnutls_ext_register</code> in
<code>gnutls_extensions.c</code> typically within <code>_gnutls_ext_init</code>.
</p>
<a name="Adding-a-new-TLS-extension"></a>
<h4 class="subheading">Adding a new TLS extension</h4>

<p>Adding support for a new TLS extension is done from time to time, and
the process to do so is not difficult.  Here are the steps you need to
follow if you wish to do this yourself.  For sake of discussion, let&rsquo;s
consider adding support for the hypothetical TLS extension
<code>foobar</code>. The following section is about adding an extension to GnuTLS,
for custom application extensions you should check the exported function
<a href="#gnutls_005fext_005fregister">gnutls_ext_register</a>.
</p>
<a name="Add-configure-option-like-_002d_002denable_002dfoobar-or-_002d_002ddisable_002dfoobar_002e"></a>
<h4 class="subsubheading">Add <code>configure</code> option like <code>--enable-foobar</code> or <code>--disable-foobar</code>.</h4>

<p>This step is useful when the extension code is large and it might be desirable
to disable the extension under some circumstances. Otherwise it can be safely
skipped.
</p>
<p>Whether to chose enable or disable depends on whether you intend to make the extension be
enabled by default.  Look at existing checks (i.e., SRP, authz) for
how to model the code.  For example:
</p>
<div class="example">
<pre class="example">AC_MSG_CHECKING([whether to disable foobar support])
AC_ARG_ENABLE(foobar,
	AS_HELP_STRING([--disable-foobar],
		[disable foobar support]),
	ac_enable_foobar=no)
if test x$ac_enable_foobar != xno; then
 AC_MSG_RESULT(no)
 AC_DEFINE(ENABLE_FOOBAR, 1, [enable foobar])
else
 ac_full=0
 AC_MSG_RESULT(yes)
fi
AM_CONDITIONAL(ENABLE_FOOBAR, test &quot;$ac_enable_foobar&quot; != &quot;no&quot;)
</pre></div>

<p>These lines should go in <code>m4/hooks.m4</code>.
</p>
<a name="Add-IANA-extension-value-to-extensions_005ft-in-gnutls_005fint_002eh_002e"></a>
<h4 class="subsubheading">Add IANA extension value to <code>extensions_t</code> in <code>gnutls_int.h</code>.</h4>

<p>A good name for the value would be GNUTLS_EXTENSION_FOOBAR.  Check
with <a href="http://www.iana.org/assignments/tls-extensiontype-values">http://www.iana.org/assignments/tls-extensiontype-values</a>
for allocated values.  For experiments, you could pick a number but
remember that some consider it a bad idea to deploy such modified
version since it will lead to interoperability problems in the future
when the IANA allocates that number to someone else, or when the
foobar protocol is allocated another number.
</p>
<a name="Add-an-entry-to-_005fgnutls_005fextensions-in-gnutls_005fextensions_002ec_002e"></a>
<h4 class="subsubheading">Add an entry to <code>_gnutls_extensions</code> in <code>gnutls_extensions.c</code>.</h4>

<p>A typical entry would be:
</p>
<div class="example">
<pre class="example">  int ret;

#if ENABLE_FOOBAR
  ret = _gnutls_ext_register (&amp;foobar_ext);
  if (ret != GNUTLS_E_SUCCESS)
    return ret;
#endif
</pre></div>

<p>Most likely you&rsquo;ll need to add an <code>#include &quot;ext/foobar.h&quot;</code>, that
will contain something like
like:
</p><div class="example">
<pre class="example">  extension_entry_st foobar_ext = {
    .name = &quot;FOOBAR&quot;,
    .type = GNUTLS_EXTENSION_FOOBAR,
    .parse_type = GNUTLS_EXT_TLS,
    .recv_func = _foobar_recv_params,
    .send_func = _foobar_send_params,
    .pack_func = _foobar_pack,
    .unpack_func = _foobar_unpack,
    .deinit_func = NULL
  }
</pre></div>

<p>The GNUTLS_EXTENSION_FOOBAR is the integer value you added to
<code>gnutls_int.h</code> earlier.  In this structure you specify the
functions to read the extension from the hello message, the function
to send the reply to, and two more functions to pack and unpack from
stored session data (e.g. when resumming a session). The <code>deinit</code> function
will be called to deinitialize the extension&rsquo;s private parameters, if any.
</p>
<p>Note that the conditional <code>ENABLE_FOOBAR</code> definition should only be 
used if step 1 with the <code>configure</code> options has taken place.
</p>
<a name="Add-new-files-that-implement-the-extension_002e"></a>
<h4 class="subsubheading">Add new files that implement the extension.</h4>

<p>The functions you are responsible to add are those mentioned in the
previous step.  They should be added in a file such as <code>ext/foobar.c</code> 
and headers should be placed in <code>ext/foobar.h</code>.
As a starter, you could add this:
</p>
<div class="example">
<pre class="example">int
_foobar_recv_params (gnutls_session_t session, const opaque * data,
                     size_t data_size)
{
  return 0;
}

int
_foobar_send_params (gnutls_session_t session, gnutls_buffer_st* data)
{
  return 0;
}

int
_foobar_pack (extension_priv_data_t epriv, gnutls_buffer_st * ps)
{
   /* Append the extension's internal state to buffer */
   return 0;
}

int
_foobar_unpack (gnutls_buffer_st * ps, extension_priv_data_t * epriv)
{
   /* Read the internal state from buffer */
   return 0;
}
</pre></div>

<p>The <code>_foobar_recv_params</code> function is responsible for
parsing incoming extension data (both in the client and server).
</p>
<p>The <code>_foobar_send_params</code> function is responsible for
sending extension data (both in the client and server).
</p>
<p>If you receive length fields that don&rsquo;t match, return
<code>GNUTLS_E_UNEXPECTED_PACKET_LENGTH</code>.  If you receive invalid
data, return <code>GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER</code>.  You can use
other error codes from the list in <a href="#Error-codes">Error codes</a>.  Return 0 on success.
</p>
<p>An extension typically stores private information in the <code>session</code>
data for later usage. That can be done using the functions 
<code>_gnutls_ext_set_session_data</code> and
<code>_gnutls_ext_get_session_data</code>. You can check simple examples
at <code>ext/max_record.c</code> and <code>ext/server_name.c</code> extensions.
That private information can be saved and restored across session 
resumption if the following functions are set:
</p>
<p>The <code>_foobar_pack</code> function is responsible for packing
internal extension data to save them in the session resumption storage.
</p>
<p>The <code>_foobar_unpack</code> function is responsible for
restoring session data from the session resumption storage.
</p>
<p>Recall that both the client and server, send and receive
parameters, and your code most likely will need to do different things
depending on which mode it is in.  It may be useful to make this
distinction explicit in the code.  Thus, for example, a better
template than above would be:
</p>
<div class="example">
<pre class="example">int
_gnutls_foobar_recv_params (gnutls_session_t session,
                            const opaque * data,
                            size_t data_size)
{
  if (session-&gt;security_parameters.entity == GNUTLS_CLIENT)
    return foobar_recv_client (session, data, data_size);
  else
    return foobar_recv_server (session, data, data_size);
}

int
_gnutls_foobar_send_params (gnutls_session_t session,
                            gnutls_buffer_st * data)
{
  if (session-&gt;security_parameters.entity == GNUTLS_CLIENT)
    return foobar_send_client (session, data);
  else
    return foobar_send_server (session, data);
}
</pre></div>

<p>The functions used would be declared as <code>static</code> functions, of
the appropriate prototype, in the same file.
When adding the files, you&rsquo;ll need to add them to <code>ext/Makefile.am</code>
as well, for example:
</p>
<div class="example">
<pre class="example">if ENABLE_FOOBAR
libgnutls_ext_la_SOURCES += ext/foobar.c ext/foobar.h
endif
</pre></div>

<a name="Add-API-functions-to-enable_002fdisable-the-extension_002e"></a>
<h4 class="subsubheading">Add API functions to enable/disable the extension.</h4>

<p>It might be desirable to allow users of the extension to
request use of the extension, or set extension specific data.  
This can be implemented by adding extension specific function calls
that can be added to <code>includes/gnutls/gnutls.h</code>,
as long as the LGPLv2.1+ applies.
The implementation of the function should lie in the <code>ext/foobar.c</code> file.
</p>
<p>To make the API available in the shared library you need to add the
symbol in <code>lib/libgnutls.map</code>, so that the symbol
is exported properly.
</p>
<p>When writing GTK-DOC style documentation for your new APIs, don&rsquo;t
forget to add <code>Since:</code> tags to indicate the GnuTLS version the
API was introduced in.
</p>
<a name="Heartbeat-extension_002e"></a>
<h4 class="subsubheading">Heartbeat extension.</h4>

<p>One such extension is HeartBeat protocol (RFC6520:
<a href="https://tools.ietf.org/html/rfc6520">https://tools.ietf.org/html/rfc6520</a>) implementation. To enable
it use option &ndash;heartbeat with example client and server supplied with
gnutls:
</p>
<div class="example">
<pre class="example">./doc/credentials/gnutls-http-serv --priority &quot;NORMAL:-CIPHER-ALL:+NULL&quot; -d 100 \
    --heartbeat --echo
./src/gnutls-cli --priority &quot;NORMAL:-CIPHER-ALL:+NULL&quot; -d 100 localhost -p 5556 \
    --insecure --heartbeat
</pre></div>

<p>After that pasting
</p><div class="example">
<pre class="example">**HEARTBEAT**
</pre></div>
<p>command into gnutls-cli will trigger corresponding command on the server and it will send HeartBeat Request with random length to client.
</p>
<p>Another way is to run capabilities check with:
</p>
<div class="example">
<pre class="example">./doc/credentials/gnutls-http-serv -d 100 --heartbeat
./src/gnutls-cli-debug localhost -p 5556
</pre></div>

<a name="Adding-a-new-Supplemental-Data-Handshake-Message"></a>
<h4 class="subheading">Adding a new Supplemental Data Handshake Message</h4>

<p>TLS handshake extensions allow to send so called supplemental data
handshake messages [<em>RFC4680</em>]. This short section explains how to 
implement a supplemental data handshake message for a given TLS extension.
</p>
<p>First of all, modify your extension <code>foobar</code> in the way, to instruct
the handshake process to send and receive supplemental data, as shown below.
</p>
<div class="example">
<pre class="example">int
_gnutls_foobar_recv_params (gnutls_session_t session, const opaque * data,
                                 size_t _data_size)
{
   ...
   gnutls_supplemental_recv(session, 1);
   ...
}

int
_gnutls_foobar_send_params (gnutls_session_t session, gnutls_buffer_st *extdata)
{
   ...
   gnutls_supplemental_send(session, 1);
   ...
}
</pre></div>

<p>Furthermore you&rsquo;ll need two new functions <code>_foobar_supp_recv_params</code>
and <code>_foobar_supp_send_params</code>, which must conform to the following 
prototypes.
</p>
<div class="example">
<pre class="example">typedef int (*gnutls_supp_recv_func)(gnutls_session_t session,
                                     const unsigned char *data,
                                     size_t data_size);
typedef int (*gnutls_supp_send_func)(gnutls_session_t session,
                                     gnutls_buffer_t buf);
</pre></div>

<p>The following example code shows how to send a
&ldquo;Hello World&rdquo; string in the supplemental data handshake message.
</p>
<div class="example">
<pre class="example">int 
_foobar_supp_recv_params(gnutls_session_t session, const opaque *data, size_t _data_size)
{
   uint8_t len = _data_size;
   unsigned char *msg;

   msg = gnutls_malloc(len);
   if (msg == NULL) return GNUTLS_E_MEMORY_ERROR;

   memcpy(msg, data, len);
   msg[len]='\0';

   /* do something with msg */
   gnutls_free(msg);

   return len;
}

int 
_foobar_supp_send_params(gnutls_session_t session, gnutls_buffer_t buf)
{
   unsigned char *msg = &quot;hello world&quot;;
   int len = strlen(msg);

   if (gnutls_buffer_append_data(buf, msg, len) &lt; 0)
       abort();

   return len;
}
</pre></div>

<p>Afterwards, register the new supplemental data using <a href="#gnutls_005fsupplemental_005fregister">gnutls_supplemental_register</a>,
at some point in your program.
</p>
<hr>
<a name="Cryptographic-Backend"></a>
<div class="header">
<p>
Previous: <a href="#TLS-Extension-Handling" accesskey="p" rel="prev">TLS Extension Handling</a>, Up: <a href="#Internal-architecture-of-GnuTLS" accesskey="u" rel="up">Internal architecture of GnuTLS</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Cryptographic-Backend-1"></a>
<h3 class="section">10.5 Cryptographic Backend</h3>
<p>Today most new processors, either for embedded or desktop systems
include either instructions  intended to speed up cryptographic operations,
or a co-processor with cryptographic capabilities. Taking advantage of 
those is a challenging task for every cryptographic  application or 
library. GnuTLS handles the cryptographic provider in a modular
way, following a layered approach to access
cryptographic operations as in <a href="#fig_002dcrypto_002dlayers">Figure 10.4</a>.
</p>
<div class="float"><a name="fig_002dcrypto_002dlayers"></a>
<img src="gnutls-crypto-layers.png" alt="gnutls-crypto-layers">

<div class="float-caption"><p><strong>Figure 10.4: </strong>GnuTLS cryptographic back-end design.</p></div></div>
<p>The TLS layer uses a cryptographic provider layer, that will in turn either 
use the default crypto provider &ndash; a software crypto library, or use an external
crypto provider, if available in the local system. The reason of handling
the external cryptographic provider in GnuTLS and not delegating it to
the cryptographic libraries, is that none of the supported cryptographic
libraries support <code>/dev/crypto</code> or CPU-optimized cryptography in
an efficient way.
</p>
<a name="Cryptographic-library-layer"></a>
<h4 class="subheading">Cryptographic library layer</h4>
<p>The Cryptographic library layer, currently supports only
libnettle. Older versions of GnuTLS used to support libgcrypt,
but it was switched with nettle mainly for performance reasons<a name="DOCF21" href="#FOOT21"><sup>21</sup></a>
and secondary because it is a simpler library to use.
In the future other cryptographic libraries might be supported as well.
</p>
<a name="External-cryptography-provider"></a>
<h4 class="subheading">External cryptography provider</h4>
<p>Systems that include a cryptographic co-processor, typically come with
kernel drivers to utilize the operations from software. For this reason 
GnuTLS provides a layer where each individual algorithm used can be replaced
by another implementation, i.e., the one provided by the driver. The
FreeBSD, OpenBSD and Linux kernels<a name="DOCF22" href="#FOOT22"><sup>22</sup></a> include already 
a number of hardware assisted implementations, and also provide an interface 
to access them, called <code>/dev/crypto</code>.
GnuTLS will take advantage of this interface if compiled with special
options. That is because in most systems where hardware-assisted 
cryptographic operations are not available, using this interface might 
actually harm performance.
</p>
<p>In systems that include cryptographic instructions with the CPU&rsquo;s
instructions set, using the kernel interface will introduce an
unneeded layer. For this reason GnuTLS includes such optimizations
found in popular processors such as the AES-NI or VIA PADLOCK instruction sets.
This is achieved using a mechanism that detects CPU capabilities and
overrides parts of crypto back-end at runtime.
The next section discusses the registration of a detected algorithm
optimization. For more information please consult the <acronym>GnuTLS</acronym>
source code in <code>lib/accelerated/</code>.
</p>
<a name="Overriding-specific-algorithms"></a>
<h4 class="subsubheading">Overriding specific algorithms</h4>
<p>When an optimized implementation of a single algorithm is available,
say a hardware assisted version of <acronym>AES-CBC</acronym> then the
following functions, from <code>crypto.h</code>, can 
be used to register those algorithms.
</p>
<ul>
<li> <a href="#gnutls_005fcrypto_005fregister_005fcipher">gnutls_crypto_register_cipher</a>:
To register a cipher algorithm.

</li><li> <a href="#gnutls_005fcrypto_005fregister_005faead_005fcipher">gnutls_crypto_register_aead_cipher</a>:
To register an AEAD cipher algorithm.

</li><li> <a href="#gnutls_005fcrypto_005fregister_005fmac">gnutls_crypto_register_mac</a>:
To register a MAC algorithm.

</li><li> <a href="#gnutls_005fcrypto_005fregister_005fdigest">gnutls_crypto_register_digest</a>:
To register a hash algorithm.

</li></ul>

<p>Those registration functions will only replace the specified algorithm
and leave the rest of subsystem intact.
</p>



<hr>
<a name="Upgrading-from-previous-versions"></a>
<div class="header">
<p>
Next: <a href="#Support" accesskey="n" rel="next">Support</a>, Previous: <a href="#Internal-architecture-of-GnuTLS" accesskey="p" rel="prev">Internal architecture of GnuTLS</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Upgrading-from-previous-versions-1"></a>
<h2 class="appendix">Appendix A Upgrading from previous versions</h2>
<a name="index-upgrading"></a>

<p>The GnuTLS library typically maintains binary and source code compatibility
across versions. The releases that have the major version increased
break binary compatibility but source compatibility is provided.
This section lists exceptional cases where changes to existing code are
required due to library changes.
</p>
<a name="Upgrading-to-2_002e12_002ex-from-previous-versions"></a>
<h3 class="heading">Upgrading to 2.12.x from previous versions</h3>

<p>GnuTLS 2.12.x is binary compatible with previous versions but changes the
semantics of <code>gnutls_transport_set_lowat</code>, which might cause breakage
in applications that relied on its default value be 1. Two fixes
are proposed:
</p><ul>
<li> Quick fix. Explicitly call <code>gnutls_transport_set_lowat (session, 1);</code>
after <a href="#gnutls_005finit">gnutls_init</a>.
</li><li> Long term fix. Because later versions of gnutls abolish the functionality 
of using the system call <code>select</code> to check for gnutls pending data, the 
function <a href="#gnutls_005frecord_005fcheck_005fpending">gnutls_record_check_pending</a> has to be used to achieve the same 
functionality as described in <a href="#Asynchronous-operation">Asynchronous operation</a>.
</li></ul>

<a name="Upgrading-to-3_002e0_002ex-from-2_002e12_002ex"></a>
<h3 class="heading">Upgrading to 3.0.x from 2.12.x</h3>

<p>GnuTLS 3.0.x is source compatible with previous versions except for the functions
listed below.
</p>
<table>
<thead><tr><th width="30%">Old function</th><th width="60%">Replacement</th></tr></thead>
<tr><td width="30%"><code>gnutls_transport_set_lowat</code></td><td width="60%">To replace its functionality the function <a href="#gnutls_005frecord_005fcheck_005fpending">gnutls_record_check_pending</a> has to be used,
as described in <a href="#Asynchronous-operation">Asynchronous operation</a></td></tr>
<tr><td width="30%"><code>gnutls_session_get_server_random</code>,
<code>gnutls_session_get_client_random</code></td><td width="60%">They are replaced by the safer function <a href="#gnutls_005fsession_005fget_005frandom">gnutls_session_get_random</a></td></tr>
<tr><td width="30%"><code>gnutls_session_get_master_secret</code></td><td width="60%">Replaced by the keying material exporters discussed in <a href="#Deriving-keys-for-other-applications_002fprotocols">Deriving keys for other applications/protocols</a></td></tr>
<tr><td width="30%"><code>gnutls_transport_set_global_errno</code></td><td width="60%">Replaced by using the system&rsquo;s errno facility or <a href="#gnutls_005ftransport_005fset_005ferrno">gnutls_transport_set_errno</a>.</td></tr>
<tr><td width="30%"><code>gnutls_x509_privkey_verify_data</code></td><td width="60%">Replaced by <a href="#gnutls_005fpubkey_005fverify_005fdata2">gnutls_pubkey_verify_data2</a>.</td></tr>
<tr><td width="30%"><code>gnutls_certificate_verify_peers</code></td><td width="60%">Replaced by <a href="#gnutls_005fcertificate_005fverify_005fpeers2">gnutls_certificate_verify_peers2</a>.</td></tr>
<tr><td width="30%"><code>gnutls_psk_netconf_derive_key</code></td><td width="60%">Removed. The key derivation function was never standardized.</td></tr>
<tr><td width="30%"><code>gnutls_session_set_finished_function</code></td><td width="60%">Removed.</td></tr>
<tr><td width="30%"><code>gnutls_ext_register</code></td><td width="60%">Removed. Extension registration API is now internal to allow easier changes in the API.</td></tr>
<tr><td width="30%"><code>gnutls_certificate_get_x509_crls</code>, <code>gnutls_certificate_get_x509_cas</code></td><td width="60%">Removed to allow updating the internal structures. Replaced by <a href="#gnutls_005fcertificate_005fget_005fissuer">gnutls_certificate_get_issuer</a>.</td></tr>
<tr><td width="30%"><code>gnutls_certificate_get_openpgp_keyring</code></td><td width="60%">Removed.</td></tr>
<tr><td width="30%"><code>gnutls_ia_</code></td><td width="60%">Removed. The inner application extensions were completely removed (they failed to be standardized).</td></tr>
</table>

<a name="Upgrading-to-3_002e1_002ex-from-3_002e0_002ex"></a>
<h3 class="heading">Upgrading to 3.1.x from 3.0.x</h3>

<p>GnuTLS 3.1.x is source and binary compatible with GnuTLS 3.0.x releases. Few
functions have been deprecated and are listed below.
</p>
<table>
<thead><tr><th width="30%">Old function</th><th width="60%">Replacement</th></tr></thead>
<tr><td width="30%"><code>gnutls_pubkey_verify_hash</code></td><td width="60%">The function <a href="#gnutls_005fpubkey_005fverify_005fhash2">gnutls_pubkey_verify_hash2</a> is provided and
is functionally equivalent and safer to use.</td></tr>
<tr><td width="30%"><code>gnutls_pubkey_verify_data</code></td><td width="60%">The function <a href="#gnutls_005fpubkey_005fverify_005fdata2">gnutls_pubkey_verify_data2</a> is provided and
is functionally equivalent and safer to use.</td></tr>
</table>

<a name="Upgrading-to-3_002e2_002ex-from-3_002e1_002ex"></a>
<h3 class="heading">Upgrading to 3.2.x from 3.1.x</h3>

<p>GnuTLS 3.2.x is source and binary compatible with GnuTLS 3.1.x releases. Few
functions have been deprecated and are listed below.
</p>
<table>
<thead><tr><th width="30%">Old function</th><th width="60%">Replacement</th></tr></thead>
<tr><td width="30%"><code>gnutls_privkey_sign_raw_data</code></td><td width="60%">The function <a href="#gnutls_005fprivkey_005fsign_005fhash">gnutls_privkey_sign_hash</a> is equivalent
when the flag <code>GNUTLS_PRIVKEY_SIGN_FLAG_TLS1_RSA</code> is specified.</td></tr>
</table>

<a name="Upgrading-to-3_002e3_002ex-from-3_002e2_002ex"></a>
<h3 class="heading">Upgrading to 3.3.x from 3.2.x</h3>

<p>GnuTLS 3.3.x is source and binary compatible with GnuTLS 3.2.x releases;
however there few changes in semantics which are listed below.
</p>
<table>
<thead><tr><th width="30%">Old function</th><th width="60%">Replacement</th></tr></thead>
<tr><td width="30%"><code>gnutls_global_init</code></td><td width="60%">No longer required. The library is initialized using a constructor.</td></tr>
<tr><td width="30%"><code>gnutls_global_deinit</code></td><td width="60%">No longer required. The library is deinitialized using a destructor.</td></tr>
</table>

<a name="Upgrading-to-3_002e4_002ex-from-3_002e3_002ex"></a>
<h3 class="heading">Upgrading to 3.4.x from 3.3.x</h3>

<p>GnuTLS 3.4.x is source compatible with GnuTLS 3.3.x releases;
however, several deprecated functions were removed, and are listed below.
</p>
<table>
<thead><tr><th width="30%">Old function</th><th width="60%">Replacement</th></tr></thead>
<tr><td width="30%">Priority string &quot;NORMAL&quot; has been modified</td><td width="60%">The following string emulates the 3.3.x behavior &quot;NORMAL:+VERS-SSL3.0:+ARCFOUR-128:+DHE-DSS:+SIGN-DSA-SHA512:+SIGN-DSA-SHA256:+SIGN-DSA-SHA1&quot;</td></tr>
<tr><td width="30%"><code>gnutls_certificate_client_set_retrieve_function</code>,
<code>gnutls_certificate_server_set_retrieve_function</code></td><td width="60%"><a href="#gnutls_005fcertificate_005fset_005fretrieve_005ffunction">gnutls_certificate_set_retrieve_function</a></td></tr>
<tr><td width="30%"><code>gnutls_certificate_set_rsa_export_params</code>,
<code>gnutls_rsa_export_get_modulus_bits</code>,
<code>gnutls_rsa_export_get_pubkey</code>,
<code>gnutls_rsa_params_cpy</code>,
<code>gnutls_rsa_params_deinit</code>,
<code>gnutls_rsa_params_export_pkcs1</code>,
<code>gnutls_rsa_params_export_raw</code>,
<code>gnutls_rsa_params_generate2</code>,
<code>gnutls_rsa_params_import_pkcs1</code>,
<code>gnutls_rsa_params_import_raw</code>,
<code>gnutls_rsa_params_init</code></td><td width="60%">No replacement; the library does not support the RSA-EXPORT ciphersuites.</td></tr>
<tr><td width="30%"><code>gnutls_pubkey_verify_hash</code>,</td><td width="60%"><a href="#gnutls_005fpubkey_005fverify_005fhash2">gnutls_pubkey_verify_hash2</a>.</td></tr>
<tr><td width="30%"><code>gnutls_pubkey_verify_data</code>,</td><td width="60%"><a href="#gnutls_005fpubkey_005fverify_005fdata2">gnutls_pubkey_verify_data2</a>.</td></tr>
<tr><td width="30%"><code>gnutls_x509_crt_get_verify_algorithm</code>,</td><td width="60%">No replacement; a similar function is <a href="#gnutls_005fx509_005fcrt_005fget_005fsignature_005falgorithm">gnutls_x509_crt_get_signature_algorithm</a>.</td></tr>
<tr><td width="30%"><code>gnutls_pubkey_get_verify_algorithm</code>,</td><td width="60%">No replacement; a similar function is <a href="#gnutls_005fpubkey_005fget_005fpreferred_005fhash_005falgorithm">gnutls_pubkey_get_preferred_hash_algorithm</a>.</td></tr>
<tr><td width="30%"><code>gnutls_certificate_type_set_priority</code>,
<code>gnutls_cipher_set_priority</code>,
<code>gnutls_compression_set_priority</code>,
<code>gnutls_kx_set_priority</code>,
<code>gnutls_mac_set_priority</code>,
<code>gnutls_protocol_set_priority</code></td><td width="60%"><a href="#gnutls_005fpriority_005fset_005fdirect">gnutls_priority_set_direct</a>.</td></tr>
<tr><td width="30%"><code>gnutls_sign_callback_get</code>,
<code>gnutls_sign_callback_set</code></td><td width="60%"><a href="#gnutls_005fprivkey_005fimport_005fext3">gnutls_privkey_import_ext3</a></td></tr>
<tr><td width="30%"><code>gnutls_x509_crt_verify_hash</code></td><td width="60%"><a href="#gnutls_005fpubkey_005fverify_005fhash2">gnutls_pubkey_verify_hash2</a></td></tr>
<tr><td width="30%"><code>gnutls_x509_crt_verify_data</code></td><td width="60%"><a href="#gnutls_005fpubkey_005fverify_005fdata2">gnutls_pubkey_verify_data2</a></td></tr>
<tr><td width="30%"><code>gnutls_privkey_sign_raw_data</code></td><td width="60%"><a href="#gnutls_005fprivkey_005fsign_005fhash">gnutls_privkey_sign_hash</a> with the flag GNUTLS_PRIVKEY_SIGN_FLAG_TLS1_RSA</td></tr>
</table>

<hr>
<a name="Support"></a>
<div class="header">
<p>
Next: <a href="#Error-codes" accesskey="n" rel="next">Error codes</a>, Previous: <a href="#Upgrading-from-previous-versions" accesskey="p" rel="prev">Upgrading from previous versions</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Support-1"></a>
<h2 class="appendix">Appendix B Support</h2>

<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Getting-help" accesskey="1">Getting help</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Commercial-Support" accesskey="2">Commercial Support</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Bug-Reports" accesskey="3">Bug Reports</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Contributing" accesskey="4">Contributing</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Certification" accesskey="5">Certification</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Getting-help"></a>
<div class="header">
<p>
Next: <a href="#Commercial-Support" accesskey="n" rel="next">Commercial Support</a>, Up: <a href="#Support" accesskey="u" rel="up">Support</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Getting-Help"></a>
<h3 class="section">B.1 Getting Help</h3>

<p>A mailing list where users may help each other exists, and you can
reach it by sending e-mail to <a href="mailto:gnutls-help@gnutls.org">gnutls-help@gnutls.org</a>.  Archives
of the mailing list discussions, and an interface to manage
subscriptions, is available through the World Wide Web at
<a href="http://lists.gnutls.org/pipermail/gnutls-help/">http://lists.gnutls.org/pipermail/gnutls-help/</a>.
</p>
<p>A mailing list for developers are also available, see
<a href="http://www.gnutls.org/lists.html">http://www.gnutls.org/lists.html</a>.
Bug reports should be sent to <a href="mailto:bugs@gnutls.org">bugs@gnutls.org</a>, see
<a href="#Bug-Reports">Bug Reports</a>.
</p>
<hr>
<a name="Commercial-Support"></a>
<div class="header">
<p>
Next: <a href="#Bug-Reports" accesskey="n" rel="next">Bug Reports</a>, Previous: <a href="#Getting-help" accesskey="p" rel="prev">Getting help</a>, Up: <a href="#Support" accesskey="u" rel="up">Support</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Commercial-Support-1"></a>
<h3 class="section">B.2 Commercial Support</h3>

<p>Commercial support is available for users of GnuTLS.  The kind of
support that can be purchased may include:
</p>
<ul>
<li> Implement new features.
Such as a new TLS extension.

</li><li> Port GnuTLS to new platforms.
This could include porting to an embedded platforms that may need
memory or size optimization.

</li><li> Integrating TLS as a security environment in your existing project.

</li><li> System design of components related to TLS.

</li></ul>

<p>If you are interested, please write to:
</p>
<pre class="verbatim">Simon Josefsson Datakonsult
Hagagatan 24
113 47 Stockholm
Sweden

E-mail: simon@josefsson.org
</pre>
<p>If your company provides support related to GnuTLS and would like to
be mentioned here, contact the authors.
</p>

<hr>
<a name="Bug-Reports"></a>
<div class="header">
<p>
Next: <a href="#Contributing" accesskey="n" rel="next">Contributing</a>, Previous: <a href="#Commercial-Support" accesskey="p" rel="prev">Commercial Support</a>, Up: <a href="#Support" accesskey="u" rel="up">Support</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Bug-Reports-1"></a>
<h3 class="section">B.3 Bug Reports</h3>
<a name="index-reporting-bugs"></a>

<p>If you think you have found a bug in GnuTLS, please investigate it and
report it.
</p>
<ul>
<li> Please make sure that the bug is really in GnuTLS, and
preferably also check that it hasn&rsquo;t already been fixed in the latest
version.

</li><li> You have to send us a test case that makes it possible for us to
reproduce the bug.

</li><li> You also have to explain what is wrong; if you get a crash, or
if the results printed are not good and in that case, in what way.
Make sure that the bug report includes all information you would need
to fix this kind of bug for someone else.

</li></ul>

<p>Please make an effort to produce a self-contained report, with
something definite that can be tested or debugged.  Vague queries or
piecemeal messages are difficult to act on and don&rsquo;t help the
development effort.
</p>
<p>If your bug report is good, we will do our best to help you to get a
corrected version of the software; if the bug report is poor, we won&rsquo;t
do anything about it (apart from asking you to send better bug
reports).
</p>
<p>If you think something in this manual is unclear, or downright
incorrect, or if the language needs to be improved, please also send a
note.
</p>
<p>Send your bug report to:
</p>
<div align="center">&lsquo;<samp>bugs@gnutls.org</samp>&rsquo;
</div>
<hr>
<a name="Contributing"></a>
<div class="header">
<p>
Next: <a href="#Certification" accesskey="n" rel="next">Certification</a>, Previous: <a href="#Bug-Reports" accesskey="p" rel="prev">Bug Reports</a>, Up: <a href="#Support" accesskey="u" rel="up">Support</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Contributing-1"></a>
<h3 class="section">B.4 Contributing</h3>
<a name="index-contributing"></a>
<a name="index-hacking"></a>

<p>If you want to submit a patch for inclusion &ndash; from solving a typo you
discovered, up to adding support for a new feature &ndash; you should
submit it as a bug report, using the process in <a href="#Bug-Reports">Bug Reports</a>.  There are some
things that you can do to increase the chances for it to be included
in the official package.
</p>
<p>Unless your patch is very small (say, under 10 lines) we require that
you assign the copyright of your work to the Free Software Foundation.
This is to protect the freedom of the project.  If you have not
already signed papers, we will send you the necessary information when
you submit your contribution.
</p>
<p>For contributions that doesn&rsquo;t consist of actual programming code, the
only guidelines are common sense.  
For code contributions, a number of style guides will help you:
</p>
<ul>
<li> Coding Style.
Follow the GNU Standards document.

<p>If you normally code using another coding standard, there is no
problem, but you should use &lsquo;<samp>indent</samp>&rsquo; to reformat the code
before submitting your work.
</p>
</li><li> Use the unified diff format &lsquo;<samp>diff -u</samp>&rsquo;.

</li><li> Return errors.
No reason whatsoever should abort the execution of the library.  Even
memory allocation errors, e.g. when malloc return NULL, should work
although result in an error code.

</li><li> Design with thread safety in mind.
Don&rsquo;t use global variables.  Don&rsquo;t even write to per-handle global
variables unless the documented behaviour of the function you write is
to write to the per-handle global variable.

</li><li> Avoid using the C math library.
It causes problems for embedded implementations, and in most
situations it is very easy to avoid using it.

</li><li> Document your functions.
Use comments before each function headers, that, if properly
formatted, are extracted into Texinfo manuals and GTK-DOC web pages.

</li><li> Supply a ChangeLog and NEWS entries, where appropriate.

</li></ul>

<hr>
<a name="Certification"></a>
<div class="header">
<p>
Previous: <a href="#Contributing" accesskey="p" rel="prev">Contributing</a>, Up: <a href="#Support" accesskey="u" rel="up">Support</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Certification-1"></a>
<h3 class="section">B.5 Certification</h3>
<a name="index-certification"></a>

<p>Many cryptographic libraries claim certifications from national or international bodies. These certifications are tied on a specific (and often restricted) version of the library or a 
specific product using the library, and typically in the case of software they assure that the algorithms implemented are correct. The major certifications known are:
</p><ul>
<li> USA&rsquo;s FIPS 140-2 at Level 1 which certifies that approved algorithms are used (see <a href="http://en.wikipedia.org/wiki/FIPS_140-2">http://en.wikipedia.org/wiki/FIPS_140-2</a>);
</li><li> Common Criteria for Information Technology Security Evaluation (CC), an international standard for verification of elaborate security claims (see <a href="http://en.wikipedia.org/wiki/Common_Criteria">http://en.wikipedia.org/wiki/Common_Criteria</a>).
</li></ul>

<p>Obtaining such a certification is an expensive and elaborate job that has no immediate value for a continuously developed free software library (as the certification is tied to the
particular version tested). While, as a free software project, we are not actively pursuing this kind of certification, GnuTLS has been FIPS-140-2 certified in several systems by
third parties. If you are, interested, see <a href="#Commercial-Support">Commercial Support</a>.
</p>
<hr>
<a name="Error-codes"></a>
<div class="header">
<p>
Next: <a href="#Supported-ciphersuites" accesskey="n" rel="next">Supported ciphersuites</a>, Previous: <a href="#Support" accesskey="p" rel="prev">Support</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Error-Codes-and-Descriptions"></a>
<h2 class="appendix">Appendix C Error Codes and Descriptions</h2>
<a name="index-error-codes"></a>

<p>The error codes used throughout the library are described below.  The
return code <code>GNUTLS_E_SUCCESS</code> indicates a successful operation, and
is guaranteed to have the value 0, so you can use it in logical
expressions.
</p>
<table>
<tr><td width="15%">0</td><td width="40%">GNUTLS_E_SUCCESS</td><td width="37%">Success.</td></tr>
<tr><td width="15%">-3</td><td width="40%">GNUTLS_E_UNKNOWN_COMPRESSION_ALGORITHM</td><td width="37%">Could not negotiate a supported compression method.</td></tr>
<tr><td width="15%">-6</td><td width="40%">GNUTLS_E_UNKNOWN_CIPHER_TYPE</td><td width="37%">The cipher type is unsupported.</td></tr>
<tr><td width="15%">-7</td><td width="40%">GNUTLS_E_LARGE_PACKET</td><td width="37%">The transmitted packet is too large (EMSGSIZE).</td></tr>
<tr><td width="15%">-8</td><td width="40%">GNUTLS_E_UNSUPPORTED_VERSION_PACKET</td><td width="37%">A packet with illegal or unsupported version was received.</td></tr>
<tr><td width="15%">-9</td><td width="40%">GNUTLS_E_UNEXPECTED_PACKET_LENGTH</td><td width="37%">A TLS packet with unexpected length was received.</td></tr>
<tr><td width="15%">-10</td><td width="40%">GNUTLS_E_INVALID_SESSION</td><td width="37%">The specified session has been invalidated for some reason.</td></tr>
<tr><td width="15%">-12</td><td width="40%">GNUTLS_E_FATAL_ALERT_RECEIVED</td><td width="37%">A TLS fatal alert has been received.</td></tr>
<tr><td width="15%">-15</td><td width="40%">GNUTLS_E_UNEXPECTED_PACKET</td><td width="37%">An unexpected TLS packet was received.</td></tr>
<tr><td width="15%">-16</td><td width="40%">GNUTLS_E_WARNING_ALERT_RECEIVED</td><td width="37%">A TLS warning alert has been received.</td></tr>
<tr><td width="15%">-18</td><td width="40%">GNUTLS_E_ERROR_IN_FINISHED_PACKET</td><td width="37%">An error was encountered at the TLS Finished packet calculation.</td></tr>
<tr><td width="15%">-19</td><td width="40%">GNUTLS_E_UNEXPECTED_HANDSHAKE_PACKET</td><td width="37%">An unexpected TLS handshake packet was received.</td></tr>
<tr><td width="15%">-21</td><td width="40%">GNUTLS_E_UNKNOWN_CIPHER_SUITE</td><td width="37%">Could not negotiate a supported cipher suite.</td></tr>
<tr><td width="15%">-22</td><td width="40%">GNUTLS_E_UNWANTED_ALGORITHM</td><td width="37%">An algorithm that is not enabled was negotiated.</td></tr>
<tr><td width="15%">-23</td><td width="40%">GNUTLS_E_MPI_SCAN_FAILED</td><td width="37%">The scanning of a large integer has failed.</td></tr>
<tr><td width="15%">-24</td><td width="40%">GNUTLS_E_DECRYPTION_FAILED</td><td width="37%">Decryption has failed.</td></tr>
<tr><td width="15%">-25</td><td width="40%">GNUTLS_E_MEMORY_ERROR</td><td width="37%">Internal error in memory allocation.</td></tr>
<tr><td width="15%">-26</td><td width="40%">GNUTLS_E_DECOMPRESSION_FAILED</td><td width="37%">Decompression of the TLS record packet has failed.</td></tr>
<tr><td width="15%">-27</td><td width="40%">GNUTLS_E_COMPRESSION_FAILED</td><td width="37%">Compression of the TLS record packet has failed.</td></tr>
<tr><td width="15%">-28</td><td width="40%">GNUTLS_E_AGAIN</td><td width="37%">Resource temporarily unavailable, try again.</td></tr>
<tr><td width="15%">-29</td><td width="40%">GNUTLS_E_EXPIRED</td><td width="37%">The requested session has expired.</td></tr>
<tr><td width="15%">-30</td><td width="40%">GNUTLS_E_DB_ERROR</td><td width="37%">Error in Database backend.</td></tr>
<tr><td width="15%">-31</td><td width="40%">GNUTLS_E_SRP_PWD_ERROR</td><td width="37%">Error in password file.</td></tr>
<tr><td width="15%">-32</td><td width="40%">GNUTLS_E_INSUFFICIENT_CREDENTIALS</td><td width="37%">Insufficient credentials for that request.</td></tr>
<tr><td width="15%">-33</td><td width="40%">GNUTLS_E_HASH_FAILED</td><td width="37%">Hashing has failed.</td></tr>
<tr><td width="15%">-34</td><td width="40%">GNUTLS_E_BASE64_DECODING_ERROR</td><td width="37%">Base64 decoding error.</td></tr>
<tr><td width="15%">-35</td><td width="40%">GNUTLS_E_MPI_PRINT_FAILED</td><td width="37%">Could not export a large integer.</td></tr>
<tr><td width="15%">-37</td><td width="40%">GNUTLS_E_REHANDSHAKE</td><td width="37%">Rehandshake was requested by the peer.</td></tr>
<tr><td width="15%">-38</td><td width="40%">GNUTLS_E_GOT_APPLICATION_DATA</td><td width="37%">TLS Application data were received, while expecting handshake data.</td></tr>
<tr><td width="15%">-39</td><td width="40%">GNUTLS_E_RECORD_LIMIT_REACHED</td><td width="37%">The upper limit of record packet sequence numbers has been reached. Wow!</td></tr>
<tr><td width="15%">-40</td><td width="40%">GNUTLS_E_ENCRYPTION_FAILED</td><td width="37%">Encryption has failed.</td></tr>
<tr><td width="15%">-43</td><td width="40%">GNUTLS_E_CERTIFICATE_ERROR</td><td width="37%">Error in the certificate.</td></tr>
<tr><td width="15%">-44</td><td width="40%">GNUTLS_E_PK_ENCRYPTION_FAILED</td><td width="37%">Public key encryption has failed.</td></tr>
<tr><td width="15%">-45</td><td width="40%">GNUTLS_E_PK_DECRYPTION_FAILED</td><td width="37%">Public key decryption has failed.</td></tr>
<tr><td width="15%">-46</td><td width="40%">GNUTLS_E_PK_SIGN_FAILED</td><td width="37%">Public key signing has failed.</td></tr>
<tr><td width="15%">-47</td><td width="40%">GNUTLS_E_X509_UNSUPPORTED_CRITICAL_EXTENSION</td><td width="37%">Unsupported critical extension in X.509 certificate.</td></tr>
<tr><td width="15%">-48</td><td width="40%">GNUTLS_E_KEY_USAGE_VIOLATION</td><td width="37%">Key usage violation in certificate has been detected.</td></tr>
<tr><td width="15%">-49</td><td width="40%">GNUTLS_E_NO_CERTIFICATE_FOUND</td><td width="37%">No certificate was found.</td></tr>
<tr><td width="15%">-50</td><td width="40%">GNUTLS_E_INVALID_REQUEST</td><td width="37%">The request is invalid.</td></tr>
<tr><td width="15%">-51</td><td width="40%">GNUTLS_E_SHORT_MEMORY_BUFFER</td><td width="37%">The given memory buffer is too short to hold parameters.</td></tr>
<tr><td width="15%">-52</td><td width="40%">GNUTLS_E_INTERRUPTED</td><td width="37%">Function was interrupted.</td></tr>
<tr><td width="15%">-53</td><td width="40%">GNUTLS_E_PUSH_ERROR</td><td width="37%">Error in the push function.</td></tr>
<tr><td width="15%">-54</td><td width="40%">GNUTLS_E_PULL_ERROR</td><td width="37%">Error in the pull function.</td></tr>
<tr><td width="15%">-55</td><td width="40%">GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER</td><td width="37%">An illegal parameter has been received.</td></tr>
<tr><td width="15%">-56</td><td width="40%">GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</td><td width="37%">The requested data were not available.</td></tr>
<tr><td width="15%">-57</td><td width="40%">GNUTLS_E_PKCS1_WRONG_PAD</td><td width="37%">Wrong padding in PKCS1 packet.</td></tr>
<tr><td width="15%">-58</td><td width="40%">GNUTLS_E_RECEIVED_ILLEGAL_EXTENSION</td><td width="37%">An illegal TLS extension was received.</td></tr>
<tr><td width="15%">-59</td><td width="40%">GNUTLS_E_INTERNAL_ERROR</td><td width="37%">GnuTLS internal error.</td></tr>
<tr><td width="15%">-60</td><td width="40%">GNUTLS_E_CERTIFICATE_KEY_MISMATCH</td><td width="37%">The certificate and the given key do not match.</td></tr>
<tr><td width="15%">-61</td><td width="40%">GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE</td><td width="37%">The certificate type is not supported.</td></tr>
<tr><td width="15%">-62</td><td width="40%">GNUTLS_E_X509_UNKNOWN_SAN</td><td width="37%">Unknown Subject Alternative name in X.509 certificate.</td></tr>
<tr><td width="15%">-63</td><td width="40%">GNUTLS_E_DH_PRIME_UNACCEPTABLE</td><td width="37%">The Diffie-Hellman prime sent by the server is not acceptable (not long enough).</td></tr>
<tr><td width="15%">-64</td><td width="40%">GNUTLS_E_FILE_ERROR</td><td width="37%">Error while reading file.</td></tr>
<tr><td width="15%">-67</td><td width="40%">GNUTLS_E_ASN1_ELEMENT_NOT_FOUND</td><td width="37%">ASN1 parser: Element was not found.</td></tr>
<tr><td width="15%">-68</td><td width="40%">GNUTLS_E_ASN1_IDENTIFIER_NOT_FOUND</td><td width="37%">ASN1 parser: Identifier was not found</td></tr>
<tr><td width="15%">-69</td><td width="40%">GNUTLS_E_ASN1_DER_ERROR</td><td width="37%">ASN1 parser: Error in DER parsing.</td></tr>
<tr><td width="15%">-70</td><td width="40%">GNUTLS_E_ASN1_VALUE_NOT_FOUND</td><td width="37%">ASN1 parser: Value was not found.</td></tr>
<tr><td width="15%">-71</td><td width="40%">GNUTLS_E_ASN1_GENERIC_ERROR</td><td width="37%">ASN1 parser: Generic parsing error.</td></tr>
<tr><td width="15%">-72</td><td width="40%">GNUTLS_E_ASN1_VALUE_NOT_VALID</td><td width="37%">ASN1 parser: Value is not valid.</td></tr>
<tr><td width="15%">-73</td><td width="40%">GNUTLS_E_ASN1_TAG_ERROR</td><td width="37%">ASN1 parser: Error in TAG.</td></tr>
<tr><td width="15%">-74</td><td width="40%">GNUTLS_E_ASN1_TAG_IMPLICIT</td><td width="37%">ASN1 parser: error in implicit tag</td></tr>
<tr><td width="15%">-75</td><td width="40%">GNUTLS_E_ASN1_TYPE_ANY_ERROR</td><td width="37%">ASN1 parser: Error in type &rsquo;ANY&rsquo;.</td></tr>
<tr><td width="15%">-76</td><td width="40%">GNUTLS_E_ASN1_SYNTAX_ERROR</td><td width="37%">ASN1 parser: Syntax error.</td></tr>
<tr><td width="15%">-77</td><td width="40%">GNUTLS_E_ASN1_DER_OVERFLOW</td><td width="37%">ASN1 parser: Overflow in DER parsing.</td></tr>
<tr><td width="15%">-78</td><td width="40%">GNUTLS_E_TOO_MANY_EMPTY_PACKETS</td><td width="37%">Too many empty record packets have been received.</td></tr>
<tr><td width="15%">-79</td><td width="40%">GNUTLS_E_OPENPGP_UID_REVOKED</td><td width="37%">The OpenPGP User ID is revoked.</td></tr>
<tr><td width="15%">-80</td><td width="40%">GNUTLS_E_UNKNOWN_PK_ALGORITHM</td><td width="37%">An unknown public key algorithm was encountered.</td></tr>
<tr><td width="15%">-81</td><td width="40%">GNUTLS_E_TOO_MANY_HANDSHAKE_PACKETS</td><td width="37%">Too many handshake packets have been received.</td></tr>
<tr><td width="15%">-84</td><td width="40%">GNUTLS_E_NO_TEMPORARY_RSA_PARAMS</td><td width="37%">No temporary RSA parameters were found.</td></tr>
<tr><td width="15%">-86</td><td width="40%">GNUTLS_E_NO_COMPRESSION_ALGORITHMS</td><td width="37%">No supported compression algorithms have been found.</td></tr>
<tr><td width="15%">-87</td><td width="40%">GNUTLS_E_NO_CIPHER_SUITES</td><td width="37%">No supported cipher suites have been found.</td></tr>
<tr><td width="15%">-88</td><td width="40%">GNUTLS_E_OPENPGP_GETKEY_FAILED</td><td width="37%">Could not get OpenPGP key.</td></tr>
<tr><td width="15%">-89</td><td width="40%">GNUTLS_E_PK_SIG_VERIFY_FAILED</td><td width="37%">Public key signature verification has failed.</td></tr>
<tr><td width="15%">-90</td><td width="40%">GNUTLS_E_ILLEGAL_SRP_USERNAME</td><td width="37%">The SRP username supplied is illegal.</td></tr>
<tr><td width="15%">-91</td><td width="40%">GNUTLS_E_SRP_PWD_PARSING_ERROR</td><td width="37%">Parsing error in password file.</td></tr>
<tr><td width="15%">-93</td><td width="40%">GNUTLS_E_NO_TEMPORARY_DH_PARAMS</td><td width="37%">No temporary DH parameters were found.</td></tr>
<tr><td width="15%">-94</td><td width="40%">GNUTLS_E_OPENPGP_FINGERPRINT_UNSUPPORTED</td><td width="37%">The OpenPGP fingerprint is not supported.</td></tr>
<tr><td width="15%">-95</td><td width="40%">GNUTLS_E_X509_UNSUPPORTED_ATTRIBUTE</td><td width="37%">The certificate has unsupported attributes.</td></tr>
<tr><td width="15%">-96</td><td width="40%">GNUTLS_E_UNKNOWN_HASH_ALGORITHM</td><td width="37%">The hash algorithm is unknown.</td></tr>
<tr><td width="15%">-97</td><td width="40%">GNUTLS_E_UNKNOWN_PKCS_CONTENT_TYPE</td><td width="37%">The PKCS structure&rsquo;s content type is unknown.</td></tr>
<tr><td width="15%">-98</td><td width="40%">GNUTLS_E_UNKNOWN_PKCS_BAG_TYPE</td><td width="37%">The PKCS structure&rsquo;s bag type is unknown.</td></tr>
<tr><td width="15%">-99</td><td width="40%">GNUTLS_E_INVALID_PASSWORD</td><td width="37%">The given password contains invalid characters.</td></tr>
<tr><td width="15%">-100</td><td width="40%">GNUTLS_E_MAC_VERIFY_FAILED</td><td width="37%">The Message Authentication Code verification failed.</td></tr>
<tr><td width="15%">-101</td><td width="40%">GNUTLS_E_CONSTRAINT_ERROR</td><td width="37%">Some constraint limits were reached.</td></tr>
<tr><td width="15%">-104</td><td width="40%">GNUTLS_E_IA_VERIFY_FAILED</td><td width="37%">Verifying TLS/IA phase checksum failed</td></tr>
<tr><td width="15%">-105</td><td width="40%">GNUTLS_E_UNKNOWN_ALGORITHM</td><td width="37%">The specified algorithm or protocol is unknown.</td></tr>
<tr><td width="15%">-106</td><td width="40%">GNUTLS_E_UNSUPPORTED_SIGNATURE_ALGORITHM</td><td width="37%">The signature algorithm is not supported.</td></tr>
<tr><td width="15%">-107</td><td width="40%">GNUTLS_E_SAFE_RENEGOTIATION_FAILED</td><td width="37%">Safe renegotiation failed.</td></tr>
<tr><td width="15%">-108</td><td width="40%">GNUTLS_E_UNSAFE_RENEGOTIATION_DENIED</td><td width="37%">Unsafe renegotiation denied.</td></tr>
<tr><td width="15%">-109</td><td width="40%">GNUTLS_E_UNKNOWN_SRP_USERNAME</td><td width="37%">The SRP username supplied is unknown.</td></tr>
<tr><td width="15%">-110</td><td width="40%">GNUTLS_E_PREMATURE_TERMINATION</td><td width="37%">The TLS connection was non-properly terminated.</td></tr>
<tr><td width="15%">-201</td><td width="40%">GNUTLS_E_BASE64_ENCODING_ERROR</td><td width="37%">Base64 encoding error.</td></tr>
<tr><td width="15%">-202</td><td width="40%">GNUTLS_E_INCOMPATIBLE_GCRYPT_LIBRARY</td><td width="37%">The crypto library version is too old.</td></tr>
<tr><td width="15%">-203</td><td width="40%">GNUTLS_E_INCOMPATIBLE_LIBTASN1_LIBRARY</td><td width="37%">The tasn1 library version is too old.</td></tr>
<tr><td width="15%">-204</td><td width="40%">GNUTLS_E_OPENPGP_KEYRING_ERROR</td><td width="37%">Error loading the keyring.</td></tr>
<tr><td width="15%">-205</td><td width="40%">GNUTLS_E_X509_UNSUPPORTED_OID</td><td width="37%">The OID is not supported.</td></tr>
<tr><td width="15%">-206</td><td width="40%">GNUTLS_E_RANDOM_FAILED</td><td width="37%">Failed to acquire random data.</td></tr>
<tr><td width="15%">-207</td><td width="40%">GNUTLS_E_BASE64_UNEXPECTED_HEADER_ERROR</td><td width="37%">Base64 unexpected header error.</td></tr>
<tr><td width="15%">-208</td><td width="40%">GNUTLS_E_OPENPGP_SUBKEY_ERROR</td><td width="37%">Could not find OpenPGP subkey.</td></tr>
<tr><td width="15%">-209</td><td width="40%">GNUTLS_E_CRYPTO_ALREADY_REGISTERED</td><td width="37%">There is already a crypto algorithm with lower priority.</td></tr>
<tr><td width="15%">-210</td><td width="40%">GNUTLS_E_HANDSHAKE_TOO_LARGE</td><td width="37%">The handshake data size is too large.</td></tr>
<tr><td width="15%">-211</td><td width="40%">GNUTLS_E_CRYPTODEV_IOCTL_ERROR</td><td width="37%">Error interfacing with /dev/crypto</td></tr>
<tr><td width="15%">-212</td><td width="40%">GNUTLS_E_CRYPTODEV_DEVICE_ERROR</td><td width="37%">Error opening /dev/crypto</td></tr>
<tr><td width="15%">-213</td><td width="40%">GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE</td><td width="37%">Channel binding data not available</td></tr>
<tr><td width="15%">-214</td><td width="40%">GNUTLS_E_BAD_COOKIE</td><td width="37%">The cookie was bad.</td></tr>
<tr><td width="15%">-215</td><td width="40%">GNUTLS_E_OPENPGP_PREFERRED_KEY_ERROR</td><td width="37%">The OpenPGP key has not a preferred key set.</td></tr>
<tr><td width="15%">-216</td><td width="40%">GNUTLS_E_INCOMPAT_DSA_KEY_WITH_TLS_PROTOCOL</td><td width="37%">The given DSA key is incompatible with the selected TLS protocol.</td></tr>
<tr><td width="15%">-217</td><td width="40%">GNUTLS_E_INSUFFICIENT_SECURITY</td><td width="37%">One of the involved algorithms has insufficient security level.</td></tr>
<tr><td width="15%">-292</td><td width="40%">GNUTLS_E_HEARTBEAT_PONG_RECEIVED</td><td width="37%">A heartbeat pong message was received.</td></tr>
<tr><td width="15%">-293</td><td width="40%">GNUTLS_E_HEARTBEAT_PING_RECEIVED</td><td width="37%">A heartbeat ping message was received.</td></tr>
<tr><td width="15%">-300</td><td width="40%">GNUTLS_E_PKCS11_ERROR</td><td width="37%">PKCS #11 error.</td></tr>
<tr><td width="15%">-301</td><td width="40%">GNUTLS_E_PKCS11_LOAD_ERROR</td><td width="37%">PKCS #11 initialization error.</td></tr>
<tr><td width="15%">-302</td><td width="40%">GNUTLS_E_PARSING_ERROR</td><td width="37%">Error in parsing.</td></tr>
<tr><td width="15%">-303</td><td width="40%">GNUTLS_E_PKCS11_PIN_ERROR</td><td width="37%">Error in provided PIN.</td></tr>
<tr><td width="15%">-305</td><td width="40%">GNUTLS_E_PKCS11_SLOT_ERROR</td><td width="37%">PKCS #11 error in slot</td></tr>
<tr><td width="15%">-306</td><td width="40%">GNUTLS_E_LOCKING_ERROR</td><td width="37%">Thread locking error</td></tr>
<tr><td width="15%">-307</td><td width="40%">GNUTLS_E_PKCS11_ATTRIBUTE_ERROR</td><td width="37%">PKCS #11 error in attribute</td></tr>
<tr><td width="15%">-308</td><td width="40%">GNUTLS_E_PKCS11_DEVICE_ERROR</td><td width="37%">PKCS #11 error in device</td></tr>
<tr><td width="15%">-309</td><td width="40%">GNUTLS_E_PKCS11_DATA_ERROR</td><td width="37%">PKCS #11 error in data</td></tr>
<tr><td width="15%">-310</td><td width="40%">GNUTLS_E_PKCS11_UNSUPPORTED_FEATURE_ERROR</td><td width="37%">PKCS #11 unsupported feature</td></tr>
<tr><td width="15%">-311</td><td width="40%">GNUTLS_E_PKCS11_KEY_ERROR</td><td width="37%">PKCS #11 error in key</td></tr>
<tr><td width="15%">-312</td><td width="40%">GNUTLS_E_PKCS11_PIN_EXPIRED</td><td width="37%">PKCS #11 PIN expired</td></tr>
<tr><td width="15%">-313</td><td width="40%">GNUTLS_E_PKCS11_PIN_LOCKED</td><td width="37%">PKCS #11 PIN locked</td></tr>
<tr><td width="15%">-314</td><td width="40%">GNUTLS_E_PKCS11_SESSION_ERROR</td><td width="37%">PKCS #11 error in session</td></tr>
<tr><td width="15%">-315</td><td width="40%">GNUTLS_E_PKCS11_SIGNATURE_ERROR</td><td width="37%">PKCS #11 error in signature</td></tr>
<tr><td width="15%">-316</td><td width="40%">GNUTLS_E_PKCS11_TOKEN_ERROR</td><td width="37%">PKCS #11 error in token</td></tr>
<tr><td width="15%">-317</td><td width="40%">GNUTLS_E_PKCS11_USER_ERROR</td><td width="37%">PKCS #11 user error</td></tr>
<tr><td width="15%">-318</td><td width="40%">GNUTLS_E_CRYPTO_INIT_FAILED</td><td width="37%">The initialization of crypto backend has failed.</td></tr>
<tr><td width="15%">-319</td><td width="40%">GNUTLS_E_TIMEDOUT</td><td width="37%">The operation timed out</td></tr>
<tr><td width="15%">-320</td><td width="40%">GNUTLS_E_USER_ERROR</td><td width="37%">The operation was cancelled due to user error</td></tr>
<tr><td width="15%">-321</td><td width="40%">GNUTLS_E_ECC_NO_SUPPORTED_CURVES</td><td width="37%">No supported ECC curves were found</td></tr>
<tr><td width="15%">-322</td><td width="40%">GNUTLS_E_ECC_UNSUPPORTED_CURVE</td><td width="37%">The curve is unsupported</td></tr>
<tr><td width="15%">-323</td><td width="40%">GNUTLS_E_PKCS11_REQUESTED_OBJECT_NOT_AVAILBLE</td><td width="37%">The requested PKCS #11 object is not available</td></tr>
<tr><td width="15%">-324</td><td width="40%">GNUTLS_E_CERTIFICATE_LIST_UNSORTED</td><td width="37%">The provided X.509 certificate list is not sorted (in subject to issuer order)</td></tr>
<tr><td width="15%">-325</td><td width="40%">GNUTLS_E_ILLEGAL_PARAMETER</td><td width="37%">An illegal parameter was found.</td></tr>
<tr><td width="15%">-326</td><td width="40%">GNUTLS_E_NO_PRIORITIES_WERE_SET</td><td width="37%">No or insufficient priorities were set.</td></tr>
<tr><td width="15%">-327</td><td width="40%">GNUTLS_E_X509_UNSUPPORTED_EXTENSION</td><td width="37%">Unsupported extension in X.509 certificate.</td></tr>
<tr><td width="15%">-328</td><td width="40%">GNUTLS_E_SESSION_EOF</td><td width="37%">Peer has terminated the connection</td></tr>
<tr><td width="15%">-329</td><td width="40%">GNUTLS_E_TPM_ERROR</td><td width="37%">TPM error.</td></tr>
<tr><td width="15%">-330</td><td width="40%">GNUTLS_E_TPM_KEY_PASSWORD_ERROR</td><td width="37%">Error in provided password for key to be loaded in TPM.</td></tr>
<tr><td width="15%">-331</td><td width="40%">GNUTLS_E_TPM_SRK_PASSWORD_ERROR</td><td width="37%">Error in provided SRK password for TPM.</td></tr>
<tr><td width="15%">-332</td><td width="40%">GNUTLS_E_TPM_SESSION_ERROR</td><td width="37%">Cannot initialize a session with the TPM.</td></tr>
<tr><td width="15%">-333</td><td width="40%">GNUTLS_E_TPM_KEY_NOT_FOUND</td><td width="37%">TPM key was not found in persistent storage.</td></tr>
<tr><td width="15%">-334</td><td width="40%">GNUTLS_E_TPM_UNINITIALIZED</td><td width="37%">TPM is not initialized.</td></tr>
<tr><td width="15%">-335</td><td width="40%">GNUTLS_E_TPM_NO_LIB</td><td width="37%">The TPM library (trousers) cannot be found.</td></tr>
<tr><td width="15%">-340</td><td width="40%">GNUTLS_E_NO_CERTIFICATE_STATUS</td><td width="37%">There is no certificate status (OCSP).</td></tr>
<tr><td width="15%">-341</td><td width="40%">GNUTLS_E_OCSP_RESPONSE_ERROR</td><td width="37%">The OCSP response is invalid</td></tr>
<tr><td width="15%">-342</td><td width="40%">GNUTLS_E_RANDOM_DEVICE_ERROR</td><td width="37%">Error in the system&rsquo;s randomness device.</td></tr>
<tr><td width="15%">-343</td><td width="40%">GNUTLS_E_AUTH_ERROR</td><td width="37%">Could not authenticate peer.</td></tr>
<tr><td width="15%">-344</td><td width="40%">GNUTLS_E_NO_APPLICATION_PROTOCOL</td><td width="37%">No common application protocol could be negotiated.</td></tr>
<tr><td width="15%">-345</td><td width="40%">GNUTLS_E_SOCKETS_INIT_ERROR</td><td width="37%">Error in sockets initialization.</td></tr>
<tr><td width="15%">-346</td><td width="40%">GNUTLS_E_KEY_IMPORT_FAILED</td><td width="37%">Failed to import the key into store.</td></tr>
<tr><td width="15%">-347</td><td width="40%">GNUTLS_E_INAPPROPRIATE_FALLBACK</td><td width="37%">A connection with inappropriate fallback was attempted.</td></tr>
<tr><td width="15%">-348</td><td width="40%">GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR</td><td width="37%">Error in the certificate verification.</td></tr>
<tr><td width="15%">-400</td><td width="40%">GNUTLS_E_SELF_TEST_ERROR</td><td width="37%">Error while performing self checks.</td></tr>
<tr><td width="15%">-401</td><td width="40%">GNUTLS_E_NO_SELF_TEST</td><td width="37%">There is no self test for this algorithm.</td></tr>
<tr><td width="15%">-402</td><td width="40%">GNUTLS_E_LIB_IN_ERROR_STATE</td><td width="37%">An error has been detected in the library and cannot continue operations.</td></tr>
<tr><td width="15%">-403</td><td width="40%">GNUTLS_E_PK_GENERATION_ERROR</td><td width="37%">Error in public key generation.</td></tr>
</table>


<hr>
<a name="Supported-ciphersuites"></a>
<div class="header">
<p>
Next: <a href="#API-reference" accesskey="n" rel="next">API reference</a>, Previous: <a href="#Error-codes" accesskey="p" rel="prev">Error codes</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Supported-Ciphersuites"></a>
<h2 class="appendix">Appendix D Supported Ciphersuites</h2>
<a name="ciphersuites"></a><a name="index-ciphersuites"></a>

<a name="Ciphersuites"></a>
<h3 class="heading">Ciphersuites</h3>
<table>
<thead><tr><th width="60%">Ciphersuite name</th><th width="20%">TLS ID</th><th width="20%">Since</th></tr></thead>
<tr><td width="60%">TLS_RSA_NULL_MD5</td><td width="20%">0x00 0x01</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_RSA_NULL_SHA1</td><td width="20%">0x00 0x02</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_RSA_NULL_SHA256</td><td width="20%">0x00 0x3B</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_ARCFOUR_128_SHA1</td><td width="20%">0x00 0x05</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_RSA_ARCFOUR_128_MD5</td><td width="20%">0x00 0x04</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_RSA_3DES_EDE_CBC_SHA1</td><td width="20%">0x00 0x0A</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_RSA_AES_128_CBC_SHA1</td><td width="20%">0x00 0x2F</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_RSA_AES_256_CBC_SHA1</td><td width="20%">0x00 0x35</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_RSA_CAMELLIA_128_CBC_SHA256</td><td width="20%">0x00 0xBA</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_CAMELLIA_256_CBC_SHA256</td><td width="20%">0x00 0xC0</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_CAMELLIA_128_CBC_SHA1</td><td width="20%">0x00 0x41</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_RSA_CAMELLIA_256_CBC_SHA1</td><td width="20%">0x00 0x84</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_RSA_AES_128_CBC_SHA256</td><td width="20%">0x00 0x3C</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_AES_256_CBC_SHA256</td><td width="20%">0x00 0x3D</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_AES_128_GCM_SHA256</td><td width="20%">0x00 0x9C</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_AES_256_GCM_SHA384</td><td width="20%">0x00 0x9D</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_CAMELLIA_128_GCM_SHA256</td><td width="20%">0xC0 0x7A</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_CAMELLIA_256_GCM_SHA384</td><td width="20%">0xC0 0x7B</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_AES_128_CCM</td><td width="20%">0xC0 0x9C</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_AES_256_CCM</td><td width="20%">0xC0 0x9D</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_AES_128_CCM_8</td><td width="20%">0xC0 0xA0</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_AES_256_CCM_8</td><td width="20%">0xC0 0xA1</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_DSS_ARCFOUR_128_SHA1</td><td width="20%">0x00 0x66</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_DSS_3DES_EDE_CBC_SHA1</td><td width="20%">0x00 0x13</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_DSS_AES_128_CBC_SHA1</td><td width="20%">0x00 0x32</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_DSS_AES_256_CBC_SHA1</td><td width="20%">0x00 0x38</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_DSS_CAMELLIA_128_CBC_SHA256</td><td width="20%">0x00 0xBD</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_DSS_CAMELLIA_256_CBC_SHA256</td><td width="20%">0x00 0xC3</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_DSS_CAMELLIA_128_CBC_SHA1</td><td width="20%">0x00 0x44</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_DSS_CAMELLIA_256_CBC_SHA1</td><td width="20%">0x00 0x87</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_DSS_AES_128_CBC_SHA256</td><td width="20%">0x00 0x40</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_DSS_AES_256_CBC_SHA256</td><td width="20%">0x00 0x6A</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_DSS_AES_128_GCM_SHA256</td><td width="20%">0x00 0xA2</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_DSS_AES_256_GCM_SHA384</td><td width="20%">0x00 0xA3</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_DSS_CAMELLIA_128_GCM_SHA256</td><td width="20%">0xC0 0x80</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_DSS_CAMELLIA_256_GCM_SHA384</td><td width="20%">0xC0 0x81</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_3DES_EDE_CBC_SHA1</td><td width="20%">0x00 0x16</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_RSA_AES_128_CBC_SHA1</td><td width="20%">0x00 0x33</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_RSA_AES_256_CBC_SHA1</td><td width="20%">0x00 0x39</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_RSA_CAMELLIA_128_CBC_SHA256</td><td width="20%">0x00 0xBE</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_CAMELLIA_256_CBC_SHA256</td><td width="20%">0x00 0xC4</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_CAMELLIA_128_CBC_SHA1</td><td width="20%">0x00 0x45</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_RSA_CAMELLIA_256_CBC_SHA1</td><td width="20%">0x00 0x88</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_RSA_AES_128_CBC_SHA256</td><td width="20%">0x00 0x67</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_AES_256_CBC_SHA256</td><td width="20%">0x00 0x6B</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_AES_128_GCM_SHA256</td><td width="20%">0x00 0x9E</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_AES_256_GCM_SHA384</td><td width="20%">0x00 0x9F</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_CAMELLIA_128_GCM_SHA256</td><td width="20%">0xC0 0x7C</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_CAMELLIA_256_GCM_SHA384</td><td width="20%">0xC0 0x7D</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_CHACHA20_POLY1305</td><td width="20%">0xCC 0xAA</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_AES_128_CCM</td><td width="20%">0xC0 0x9E</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_AES_256_CCM</td><td width="20%">0xC0 0x9F</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_AES_128_CCM_8</td><td width="20%">0xC0 0xA2</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_RSA_AES_256_CCM_8</td><td width="20%">0xC0 0xA3</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_NULL_SHA1</td><td width="20%">0xC0 0x10</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_3DES_EDE_CBC_SHA1</td><td width="20%">0xC0 0x12</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_AES_128_CBC_SHA1</td><td width="20%">0xC0 0x13</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_AES_256_CBC_SHA1</td><td width="20%">0xC0 0x14</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_AES_256_CBC_SHA384</td><td width="20%">0xC0 0x28</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_ARCFOUR_128_SHA1</td><td width="20%">0xC0 0x11</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_CAMELLIA_128_CBC_SHA256</td><td width="20%">0xC0 0x76</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_CAMELLIA_256_CBC_SHA384</td><td width="20%">0xC0 0x77</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_NULL_SHA1</td><td width="20%">0xC0 0x06</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_3DES_EDE_CBC_SHA1</td><td width="20%">0xC0 0x08</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_AES_128_CBC_SHA1</td><td width="20%">0xC0 0x09</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_AES_256_CBC_SHA1</td><td width="20%">0xC0 0x0A</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_ARCFOUR_128_SHA1</td><td width="20%">0xC0 0x07</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_CAMELLIA_128_CBC_SHA256</td><td width="20%">0xC0 0x72</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_CAMELLIA_256_CBC_SHA384</td><td width="20%">0xC0 0x73</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_AES_128_CBC_SHA256</td><td width="20%">0xC0 0x23</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_AES_128_CBC_SHA256</td><td width="20%">0xC0 0x27</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_CAMELLIA_128_GCM_SHA256</td><td width="20%">0xC0 0x86</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_CAMELLIA_256_GCM_SHA384</td><td width="20%">0xC0 0x87</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_AES_128_GCM_SHA256</td><td width="20%">0xC0 0x2B</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_AES_256_GCM_SHA384</td><td width="20%">0xC0 0x2C</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_AES_128_GCM_SHA256</td><td width="20%">0xC0 0x2F</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_AES_256_GCM_SHA384</td><td width="20%">0xC0 0x30</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_AES_256_CBC_SHA384</td><td width="20%">0xC0 0x24</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_CAMELLIA_128_GCM_SHA256</td><td width="20%">0xC0 0x8A</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_CAMELLIA_256_GCM_SHA384</td><td width="20%">0xC0 0x8B</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_RSA_CHACHA20_POLY1305</td><td width="20%">0xCC 0xA8</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_CHACHA20_POLY1305</td><td width="20%">0xCC 0xA9</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_AES_128_CCM</td><td width="20%">0xC0 0xAC</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_AES_256_CCM</td><td width="20%">0xC0 0xAD</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_AES_128_CCM_8</td><td width="20%">0xC0 0xAE</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_ECDSA_AES_256_CCM_8</td><td width="20%">0xC0 0xAF</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_PSK_3DES_EDE_CBC_SHA1</td><td width="20%">0xC0 0x34</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_PSK_AES_128_CBC_SHA1</td><td width="20%">0xC0 0x35</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_PSK_AES_256_CBC_SHA1</td><td width="20%">0xC0 0x36</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_PSK_AES_128_CBC_SHA256</td><td width="20%">0xC0 0x37</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_PSK_AES_256_CBC_SHA384</td><td width="20%">0xC0 0x38</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_PSK_ARCFOUR_128_SHA1</td><td width="20%">0xC0 0x33</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_PSK_NULL_SHA1</td><td width="20%">0xC0 0x39</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDHE_PSK_NULL_SHA256</td><td width="20%">0xC0 0x3A</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_PSK_NULL_SHA384</td><td width="20%">0xC0 0x3B</td><td width="20%">TLS1.0</td></tr>
<tr><td width="60%">TLS_ECDHE_PSK_CAMELLIA_128_CBC_SHA256</td><td width="20%">0xC0 0x9A</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_PSK_CAMELLIA_256_CBC_SHA384</td><td width="20%">0xC0 0x9B</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_ARCFOUR_128_SHA1</td><td width="20%">0x00 0x8A</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_PSK_3DES_EDE_CBC_SHA1</td><td width="20%">0x00 0x8B</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_PSK_AES_128_CBC_SHA1</td><td width="20%">0x00 0x8C</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_PSK_AES_256_CBC_SHA1</td><td width="20%">0x00 0x8D</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_PSK_AES_128_CBC_SHA256</td><td width="20%">0x00 0xAE</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_AES_256_GCM_SHA384</td><td width="20%">0x00 0xA9</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_CAMELLIA_128_GCM_SHA256</td><td width="20%">0xC0 0x8E</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_CAMELLIA_256_GCM_SHA384</td><td width="20%">0xC0 0x8F</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_AES_128_GCM_SHA256</td><td width="20%">0x00 0xA8</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_NULL_SHA1</td><td width="20%">0x00 0x2C</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_PSK_NULL_SHA256</td><td width="20%">0x00 0xB0</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_CAMELLIA_128_CBC_SHA256</td><td width="20%">0xC0 0x94</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_CAMELLIA_256_CBC_SHA384</td><td width="20%">0xC0 0x95</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_AES_256_CBC_SHA384</td><td width="20%">0x00 0xAF</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_NULL_SHA384</td><td width="20%">0x00 0xB1</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_PSK_ARCFOUR_128_SHA1</td><td width="20%">0x00 0x92</td><td width="20%">TLS1.0</td></tr>
<tr><td width="60%">TLS_RSA_PSK_3DES_EDE_CBC_SHA1</td><td width="20%">0x00 0x93</td><td width="20%">TLS1.0</td></tr>
<tr><td width="60%">TLS_RSA_PSK_AES_128_CBC_SHA1</td><td width="20%">0x00 0x94</td><td width="20%">TLS1.0</td></tr>
<tr><td width="60%">TLS_RSA_PSK_AES_256_CBC_SHA1</td><td width="20%">0x00 0x95</td><td width="20%">TLS1.0</td></tr>
<tr><td width="60%">TLS_RSA_PSK_CAMELLIA_128_GCM_SHA256</td><td width="20%">0xC0 0x92</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_PSK_CAMELLIA_256_GCM_SHA384</td><td width="20%">0xC0 0x93</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_PSK_AES_128_GCM_SHA256</td><td width="20%">0x00 0xAC</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_PSK_AES_128_CBC_SHA256</td><td width="20%">0x00 0xB6</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_PSK_NULL_SHA1</td><td width="20%">0x00 0x2E</td><td width="20%">TLS1.0</td></tr>
<tr><td width="60%">TLS_RSA_PSK_NULL_SHA256</td><td width="20%">0x00 0xB8</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_PSK_AES_256_GCM_SHA384</td><td width="20%">0x00 0xAD</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_PSK_AES_256_CBC_SHA384</td><td width="20%">0x00 0xB7</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_PSK_NULL_SHA384</td><td width="20%">0x00 0xB9</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_PSK_CAMELLIA_128_CBC_SHA256</td><td width="20%">0xC0 0x98</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_PSK_CAMELLIA_256_CBC_SHA384</td><td width="20%">0xC0 0x99</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_ARCFOUR_128_SHA1</td><td width="20%">0x00 0x8E</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_PSK_3DES_EDE_CBC_SHA1</td><td width="20%">0x00 0x8F</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_PSK_AES_128_CBC_SHA1</td><td width="20%">0x00 0x90</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_PSK_AES_256_CBC_SHA1</td><td width="20%">0x00 0x91</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_PSK_AES_128_CBC_SHA256</td><td width="20%">0x00 0xB2</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_AES_128_GCM_SHA256</td><td width="20%">0x00 0xAA</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_NULL_SHA1</td><td width="20%">0x00 0x2D</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DHE_PSK_NULL_SHA256</td><td width="20%">0x00 0xB4</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_NULL_SHA384</td><td width="20%">0x00 0xB5</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_AES_256_CBC_SHA384</td><td width="20%">0x00 0xB3</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_AES_256_GCM_SHA384</td><td width="20%">0x00 0xAB</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_CAMELLIA_128_CBC_SHA256</td><td width="20%">0xC0 0x96</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_CAMELLIA_256_CBC_SHA384</td><td width="20%">0xC0 0x97</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_CAMELLIA_128_GCM_SHA256</td><td width="20%">0xC0 0x90</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_CAMELLIA_256_GCM_SHA384</td><td width="20%">0xC0 0x91</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_AES_128_CCM</td><td width="20%">0xC0 0xA4</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_AES_256_CCM</td><td width="20%">0xC0 0xA5</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_AES_128_CCM</td><td width="20%">0xC0 0xA6</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_AES_256_CCM</td><td width="20%">0xC0 0xA7</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_AES_128_CCM_8</td><td width="20%">0xC0 0xA8</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_AES_256_CCM_8</td><td width="20%">0xC0 0xA9</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_AES_128_CCM_8</td><td width="20%">0xC0 0xAA</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_AES_256_CCM_8</td><td width="20%">0xC0 0xAB</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DHE_PSK_CHACHA20_POLY1305</td><td width="20%">0xCC 0xAD</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDHE_PSK_CHACHA20_POLY1305</td><td width="20%">0xCC 0xAC</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_RSA_PSK_CHACHA20_POLY1305</td><td width="20%">0xCC 0xAE</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_PSK_CHACHA20_POLY1305</td><td width="20%">0xCC 0xAB</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DH_ANON_ARCFOUR_128_MD5</td><td width="20%">0x00 0x18</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DH_ANON_3DES_EDE_CBC_SHA1</td><td width="20%">0x00 0x1B</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DH_ANON_AES_128_CBC_SHA1</td><td width="20%">0x00 0x34</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DH_ANON_AES_256_CBC_SHA1</td><td width="20%">0x00 0x3A</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DH_ANON_CAMELLIA_128_CBC_SHA256</td><td width="20%">0x00 0xBF</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DH_ANON_CAMELLIA_256_CBC_SHA256</td><td width="20%">0x00 0xC5</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DH_ANON_CAMELLIA_128_CBC_SHA1</td><td width="20%">0x00 0x46</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DH_ANON_CAMELLIA_256_CBC_SHA1</td><td width="20%">0x00 0x89</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_DH_ANON_AES_128_CBC_SHA256</td><td width="20%">0x00 0x6C</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DH_ANON_AES_256_CBC_SHA256</td><td width="20%">0x00 0x6D</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DH_ANON_AES_128_GCM_SHA256</td><td width="20%">0x00 0xA6</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DH_ANON_AES_256_GCM_SHA384</td><td width="20%">0x00 0xA7</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DH_ANON_CAMELLIA_128_GCM_SHA256</td><td width="20%">0xC0 0x84</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_DH_ANON_CAMELLIA_256_GCM_SHA384</td><td width="20%">0xC0 0x85</td><td width="20%">TLS1.2</td></tr>
<tr><td width="60%">TLS_ECDH_ANON_NULL_SHA1</td><td width="20%">0xC0 0x15</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDH_ANON_3DES_EDE_CBC_SHA1</td><td width="20%">0xC0 0x17</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDH_ANON_AES_128_CBC_SHA1</td><td width="20%">0xC0 0x18</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDH_ANON_AES_256_CBC_SHA1</td><td width="20%">0xC0 0x19</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_ECDH_ANON_ARCFOUR_128_SHA1</td><td width="20%">0xC0 0x16</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_SRP_SHA_3DES_EDE_CBC_SHA1</td><td width="20%">0xC0 0x1A</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_SRP_SHA_AES_128_CBC_SHA1</td><td width="20%">0xC0 0x1D</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_SRP_SHA_AES_256_CBC_SHA1</td><td width="20%">0xC0 0x20</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_SRP_SHA_DSS_3DES_EDE_CBC_SHA1</td><td width="20%">0xC0 0x1C</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_SRP_SHA_RSA_3DES_EDE_CBC_SHA1</td><td width="20%">0xC0 0x1B</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_SRP_SHA_DSS_AES_128_CBC_SHA1</td><td width="20%">0xC0 0x1F</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_SRP_SHA_RSA_AES_128_CBC_SHA1</td><td width="20%">0xC0 0x1E</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_SRP_SHA_DSS_AES_256_CBC_SHA1</td><td width="20%">0xC0 0x22</td><td width="20%">SSL3.0</td></tr>
<tr><td width="60%">TLS_SRP_SHA_RSA_AES_256_CBC_SHA1</td><td width="20%">0xC0 0x21</td><td width="20%">SSL3.0</td></tr>
</table>


<a name="Certificate-types"></a>
<h3 class="heading">Certificate types</h3>
<dl compact="compact">
<dt><code>X.509</code></dt>
<dt><code>OPENPGP</code></dt>
</dl>

<a name="Protocols"></a>
<h3 class="heading">Protocols</h3>
<dl compact="compact">
<dt><code>SSL3.0</code></dt>
<dt><code>TLS1.0</code></dt>
<dt><code>TLS1.1</code></dt>
<dt><code>TLS1.2</code></dt>
<dt><code>DTLS0.9</code></dt>
<dt><code>DTLS1.0</code></dt>
<dt><code>DTLS1.2</code></dt>
</dl>

<a name="Ciphers"></a>
<h3 class="heading">Ciphers</h3>
<dl compact="compact">
<dt><code>AES-256-CBC</code></dt>
<dt><code>AES-192-CBC</code></dt>
<dt><code>AES-128-CBC</code></dt>
<dt><code>AES-128-GCM</code></dt>
<dt><code>AES-256-GCM</code></dt>
<dt><code>AES-128-CCM</code></dt>
<dt><code>AES-256-CCM</code></dt>
<dt><code>AES-128-CCM-8</code></dt>
<dt><code>AES-256-CCM-8</code></dt>
<dt><code>ARCFOUR-128</code></dt>
<dt><code>ESTREAM-SALSA20-256</code></dt>
<dt><code>SALSA20-256</code></dt>
<dt><code>CAMELLIA-256-CBC</code></dt>
<dt><code>CAMELLIA-192-CBC</code></dt>
<dt><code>CAMELLIA-128-CBC</code></dt>
<dt><code>CHACHA20-POLY1305</code></dt>
<dt><code>CAMELLIA-128-GCM</code></dt>
<dt><code>CAMELLIA-256-GCM</code></dt>
<dt><code>3DES-CBC</code></dt>
<dt><code>DES-CBC</code></dt>
<dt><code>RC2-40</code></dt>
<dt><code>NULL</code></dt>
</dl>

<a name="MAC-algorithms"></a>
<h3 class="heading">MAC algorithms</h3>
<dl compact="compact">
<dt><code>SHA1</code></dt>
<dt><code>MD5</code></dt>
<dt><code>SHA256</code></dt>
<dt><code>SHA384</code></dt>
<dt><code>SHA512</code></dt>
<dt><code>SHA224</code></dt>
<dt><code>UMAC-96</code></dt>
<dt><code>UMAC-128</code></dt>
<dt><code>AEAD</code></dt>
</dl>

<a name="Key-exchange-methods"></a>
<h3 class="heading">Key exchange methods</h3>
<dl compact="compact">
<dt><code>ANON-DH</code></dt>
<dt><code>ANON-ECDH</code></dt>
<dt><code>RSA</code></dt>
<dt><code>DHE-RSA</code></dt>
<dt><code>DHE-DSS</code></dt>
<dt><code>ECDHE-RSA</code></dt>
<dt><code>ECDHE-ECDSA</code></dt>
<dt><code>SRP-DSS</code></dt>
<dt><code>SRP-RSA</code></dt>
<dt><code>SRP</code></dt>
<dt><code>PSK</code></dt>
<dt><code>RSA-PSK</code></dt>
<dt><code>DHE-PSK</code></dt>
<dt><code>ECDHE-PSK</code></dt>
<dt><code>RSA-EXPORT</code></dt>
</dl>

<a name="Public-key-algorithms-2"></a>
<h3 class="heading">Public key algorithms</h3>
<dl compact="compact">
<dt><code>RSA</code></dt>
<dt><code>DSA</code></dt>
<dt><code>EC</code></dt>
</dl>

<a name="Public-key-signature-algorithms"></a>
<h3 class="heading">Public key signature algorithms</h3>
<dl compact="compact">
<dt><code>RSA-SHA1</code></dt>
<dt><code>RSA-SHA1</code></dt>
<dt><code>RSA-SHA224</code></dt>
<dt><code>RSA-SHA256</code></dt>
<dt><code>RSA-SHA384</code></dt>
<dt><code>RSA-SHA512</code></dt>
<dt><code>RSA-RMD160</code></dt>
<dt><code>DSA-SHA1</code></dt>
<dt><code>DSA-SHA1</code></dt>
<dt><code>DSA-SHA224</code></dt>
<dt><code>DSA-SHA256</code></dt>
<dt><code>RSA-MD5</code></dt>
<dt><code>RSA-MD5</code></dt>
<dt><code>RSA-MD2</code></dt>
<dt><code>ECDSA-SHA1</code></dt>
<dt><code>ECDSA-SHA224</code></dt>
<dt><code>ECDSA-SHA256</code></dt>
<dt><code>ECDSA-SHA384</code></dt>
<dt><code>ECDSA-SHA512</code></dt>
</dl>

<a name="Elliptic-curves"></a>
<h3 class="heading">Elliptic curves</h3>
<dl compact="compact">
<dt><code>SECP192R1</code></dt>
<dt><code>SECP224R1</code></dt>
<dt><code>SECP256R1</code></dt>
<dt><code>SECP384R1</code></dt>
<dt><code>SECP521R1</code></dt>
</dl>

<a name="Compression-methods"></a>
<h3 class="heading">Compression methods</h3>
<dl compact="compact">
<dt><code>DEFLATE</code></dt>
<dt><code>NULL</code></dt>
</dl>


<hr>
<a name="API-reference"></a>
<div class="header">
<p>
Next: <a href="#Copying-Information" accesskey="n" rel="next">Copying Information</a>, Previous: <a href="#Supported-ciphersuites" accesskey="p" rel="prev">Supported ciphersuites</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="API-reference-1"></a>
<h2 class="appendix">Appendix E API reference</h2>
<a name="index-API-reference"></a>

<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="#Core-TLS-API" accesskey="1">Core TLS API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Datagram-TLS-API" accesskey="2">Datagram TLS API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#X509-certificate-API" accesskey="3">X509 certificate API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#PKCS-7-API" accesskey="4">PKCS 7 API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OCSP-API" accesskey="5">OCSP API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#OpenPGP-API" accesskey="6">OpenPGP API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#PKCS-12-API" accesskey="7">PKCS 12 API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#PKCS-11-API" accesskey="8">PKCS 11 API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#TPM-API" accesskey="9">TPM API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Abstract-key-API">Abstract key API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#DANE-API">DANE API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Cryptographic-API">Cryptographic API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="#Compatibility-API">Compatibility API</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
</table>

<hr>
<a name="Core-TLS-API"></a>
<div class="header">
<p>
Next: <a href="#Datagram-TLS-API" accesskey="n" rel="next">Datagram TLS API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Core-TLS-API-1"></a>
<h3 class="section">E.1 Core TLS API</h3>

<p>The prototypes for the following functions lie in
<samp>gnutls/gnutls.h</samp>.
</p>

<a name="gnutls_005falert_005fget-1"></a>
<h4 class="subheading">gnutls_alert_get</h4>
<a name="gnutls_005falert_005fget"></a><dl>
<dt><a name="index-gnutls_005falert_005fget-1"></a>Function: <em>gnutls_alert_description_t</em> <strong>gnutls_alert_get</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function will return the last alert number received.  This
function should be called when <code>GNUTLS_E_WARNING_ALERT_RECEIVED</code>  or
<code>GNUTLS_E_FATAL_ALERT_RECEIVED</code>  errors are returned by a gnutls
function.  The peer may send alerts if he encounters an error.
If no alert has been received the returned value is undefined.
</p>
<p><strong>Returns:</strong> the last alert received, a
<code>gnutls_alert_description_t</code>  value.
</p></dd></dl>

<a name="gnutls_005falert_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_alert_get_name</h4>
<a name="gnutls_005falert_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005falert_005fget_005fname-1"></a>Function: <em>const char *</em> <strong>gnutls_alert_get_name</strong> <em>(gnutls_alert_description_t <var>alert</var>)</em></dt>
<dd><p><var>alert</var>: is an alert number.
</p>
<p>This function will return a string that describes the given alert
number, or <code>NULL</code> .  See <code>gnutls_alert_get()</code> .
</p>
<p><strong>Returns:</strong> string corresponding to <code>gnutls_alert_description_t</code>  value.
</p></dd></dl>

<a name="gnutls_005falert_005fget_005fstrname-1"></a>
<h4 class="subheading">gnutls_alert_get_strname</h4>
<a name="gnutls_005falert_005fget_005fstrname"></a><dl>
<dt><a name="index-gnutls_005falert_005fget_005fstrname"></a>Function: <em>const char *</em> <strong>gnutls_alert_get_strname</strong> <em>(gnutls_alert_description_t <var>alert</var>)</em></dt>
<dd><p><var>alert</var>: is an alert number.
</p>
<p>This function will return a string of the name of the alert.
</p>
<p><strong>Returns:</strong> string corresponding to <code>gnutls_alert_description_t</code>  value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005falert_005fsend-1"></a>
<h4 class="subheading">gnutls_alert_send</h4>
<a name="gnutls_005falert_005fsend"></a><dl>
<dt><a name="index-gnutls_005falert_005fsend-1"></a>Function: <em>int</em> <strong>gnutls_alert_send</strong> <em>(gnutls_session_t <var>session</var>, gnutls_alert_level_t <var>level</var>, gnutls_alert_description_t <var>desc</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>level</var>: is the level of the alert
</p>
<p><var>desc</var>: is the alert description
</p>
<p>This function will send an alert to the peer in order to inform
him of something important (eg. his Certificate could not be verified).
If the alert level is Fatal then the peer is expected to close the
connection, otherwise he may ignore the alert and continue.
</p>
<p>The error code of the underlying record send function will be
returned, so you may also receive <code>GNUTLS_E_INTERRUPTED</code>  or
<code>GNUTLS_E_AGAIN</code>  as well.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005falert_005fsend_005fappropriate-1"></a>
<h4 class="subheading">gnutls_alert_send_appropriate</h4>
<a name="gnutls_005falert_005fsend_005fappropriate"></a><dl>
<dt><a name="index-gnutls_005falert_005fsend_005fappropriate"></a>Function: <em>int</em> <strong>gnutls_alert_send_appropriate</strong> <em>(gnutls_session_t <var>session</var>, int <var>err</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>err</var>: is an integer
</p>
<p>Sends an alert to the peer depending on the error code returned by
a gnutls function. This function will call <code>gnutls_error_to_alert()</code> 
to determine the appropriate alert to send.
</p>
<p>This function may also return <code>GNUTLS_E_AGAIN</code> , or
<code>GNUTLS_E_INTERRUPTED</code> .
</p>
<p>If the return value is <code>GNUTLS_E_INVALID_REQUEST</code> , then no alert has
been sent to the peer.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005falpn_005fget_005fselected_005fprotocol-1"></a>
<h4 class="subheading">gnutls_alpn_get_selected_protocol</h4>
<a name="gnutls_005falpn_005fget_005fselected_005fprotocol"></a><dl>
<dt><a name="index-gnutls_005falpn_005fget_005fselected_005fprotocol"></a>Function: <em>int</em> <strong>gnutls_alpn_get_selected_protocol</strong> <em>(gnutls_session_t <var>session</var>, gnutls_datum_t * <var>protocol</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>protocol</var>: will hold the protocol name
</p>
<p>This function allows you to get the negotiated protocol name. The
returned protocol should be treated as opaque, constant value and
only valid during the session life.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p>Since 3.2.0
</p></dd></dl>

<a name="gnutls_005falpn_005fset_005fprotocols-1"></a>
<h4 class="subheading">gnutls_alpn_set_protocols</h4>
<a name="gnutls_005falpn_005fset_005fprotocols"></a><dl>
<dt><a name="index-gnutls_005falpn_005fset_005fprotocols"></a>Function: <em>int</em> <strong>gnutls_alpn_set_protocols</strong> <em>(gnutls_session_t <var>session</var>, const gnutls_datum_t * <var>protocols</var>, unsigned <var>protocols_size</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>protocols</var>: is the protocol names to add.
</p>
<p><var>protocols_size</var>: the number of protocols to add.
</p>
<p><var>flags</var>: zero or <code>GNUTLS_ALPN_</code> *
</p>
<p>This function is to be used by both clients and servers, to declare
the supported ALPN protocols, which are used during negotiation with peer.
</p>
<p>If <code>GNUTLS_ALPN_MAND</code>  is specified the connection will be aborted
if no matching ALPN protocol is found.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p>Since 3.2.0
</p></dd></dl>

<a name="gnutls_005fanon_005fallocate_005fclient_005fcredentials-1"></a>
<h4 class="subheading">gnutls_anon_allocate_client_credentials</h4>
<a name="gnutls_005fanon_005fallocate_005fclient_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fanon_005fallocate_005fclient_005fcredentials"></a>Function: <em>int</em> <strong>gnutls_anon_allocate_client_credentials</strong> <em>(gnutls_anon_client_credentials_t *      <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a pointer to a <code>gnutls_anon_client_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus
this helper function is provided in order to allocate it.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fanon_005fallocate_005fserver_005fcredentials-1"></a>
<h4 class="subheading">gnutls_anon_allocate_server_credentials</h4>
<a name="gnutls_005fanon_005fallocate_005fserver_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fanon_005fallocate_005fserver_005fcredentials"></a>Function: <em>int</em> <strong>gnutls_anon_allocate_server_credentials</strong> <em>(gnutls_anon_server_credentials_t *      <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a pointer to a <code>gnutls_anon_server_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus this
helper function is provided in order to allocate it.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fanon_005ffree_005fclient_005fcredentials-1"></a>
<h4 class="subheading">gnutls_anon_free_client_credentials</h4>
<a name="gnutls_005fanon_005ffree_005fclient_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fanon_005ffree_005fclient_005fcredentials"></a>Function: <em>void</em> <strong>gnutls_anon_free_client_credentials</strong> <em>(gnutls_anon_client_credentials_t <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_anon_client_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus this
helper function is provided in order to free (deallocate) it.
</p></dd></dl>

<a name="gnutls_005fanon_005ffree_005fserver_005fcredentials-1"></a>
<h4 class="subheading">gnutls_anon_free_server_credentials</h4>
<a name="gnutls_005fanon_005ffree_005fserver_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fanon_005ffree_005fserver_005fcredentials"></a>Function: <em>void</em> <strong>gnutls_anon_free_server_credentials</strong> <em>(gnutls_anon_server_credentials_t <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_anon_server_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus this
helper function is provided in order to free (deallocate) it.
</p></dd></dl>

<a name="gnutls_005fanon_005fset_005fparams_005ffunction-1"></a>
<h4 class="subheading">gnutls_anon_set_params_function</h4>
<a name="gnutls_005fanon_005fset_005fparams_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fanon_005fset_005fparams_005ffunction"></a>Function: <em>void</em> <strong>gnutls_anon_set_params_function</strong> <em>(gnutls_anon_server_credentials_t <var>res</var>, gnutls_params_function * <var>func</var>)</em></dt>
<dd><p><var>res</var>: is a gnutls_anon_server_credentials_t type
</p>
<p><var>func</var>: is the function to be called
</p>
<p>This function will set a callback in order for the server to get
the Diffie-Hellman or RSA parameters for anonymous authentication.
The callback should return <code>GNUTLS_E_SUCCESS</code>  (0) on success.
</p></dd></dl>

<a name="gnutls_005fanon_005fset_005fserver_005fdh_005fparams-1"></a>
<h4 class="subheading">gnutls_anon_set_server_dh_params</h4>
<a name="gnutls_005fanon_005fset_005fserver_005fdh_005fparams"></a><dl>
<dt><a name="index-gnutls_005fanon_005fset_005fserver_005fdh_005fparams"></a>Function: <em>void</em> <strong>gnutls_anon_set_server_dh_params</strong> <em>(gnutls_anon_server_credentials_t <var>res</var>, gnutls_dh_params_t <var>dh_params</var>)</em></dt>
<dd><p><var>res</var>: is a gnutls_anon_server_credentials_t type
</p>
<p><var>dh_params</var>: The Diffie-Hellman parameters.
</p>
<p>This function will set the Diffie-Hellman parameters for an
anonymous server to use.  These parameters will be used in
Anonymous Diffie-Hellman cipher suites.
</p></dd></dl>

<a name="gnutls_005fanon_005fset_005fserver_005fparams_005ffunction-1"></a>
<h4 class="subheading">gnutls_anon_set_server_params_function</h4>
<a name="gnutls_005fanon_005fset_005fserver_005fparams_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fanon_005fset_005fserver_005fparams_005ffunction"></a>Function: <em>void</em> <strong>gnutls_anon_set_server_params_function</strong> <em>(gnutls_anon_server_credentials_t            <var>res</var>, gnutls_params_function * <var>func</var>)</em></dt>
<dd><p><var>res</var>: is a gnutls_certificate_credentials_t type
</p>
<p><var>func</var>: is the function to be called
</p>
<p>This function will set a callback in order for the server to get
the Diffie-Hellman parameters for anonymous authentication.  The
callback should return <code>GNUTLS_E_SUCCESS</code>  (0) on success.
</p></dd></dl>

<a name="gnutls_005fauth_005fclient_005fget_005ftype-1"></a>
<h4 class="subheading">gnutls_auth_client_get_type</h4>
<a name="gnutls_005fauth_005fclient_005fget_005ftype"></a><dl>
<dt><a name="index-gnutls_005fauth_005fclient_005fget_005ftype"></a>Function: <em>gnutls_credentials_type_t</em> <strong>gnutls_auth_client_get_type</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Returns the type of credentials that were used for client authentication.
The returned information is to be used to distinguish the function used
to access authentication data.
</p>
<p><strong>Returns:</strong> The type of credentials for the client authentication
schema, a <code>gnutls_credentials_type_t</code>  type.
</p></dd></dl>

<a name="gnutls_005fauth_005fget_005ftype-1"></a>
<h4 class="subheading">gnutls_auth_get_type</h4>
<a name="gnutls_005fauth_005fget_005ftype"></a><dl>
<dt><a name="index-gnutls_005fauth_005fget_005ftype"></a>Function: <em>gnutls_credentials_type_t</em> <strong>gnutls_auth_get_type</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Returns type of credentials for the current authentication schema.
The returned information is to be used to distinguish the function used
to access authentication data.
</p>
<p>Eg. for CERTIFICATE ciphersuites (key exchange algorithms:
<code>GNUTLS_KX_RSA</code> , <code>GNUTLS_KX_DHE_RSA</code> ), the same function are to be
used to access the authentication data.
</p>
<p><strong>Returns:</strong> The type of credentials for the current authentication
schema, a <code>gnutls_credentials_type_t</code>  type.
</p></dd></dl>

<a name="gnutls_005fauth_005fserver_005fget_005ftype-1"></a>
<h4 class="subheading">gnutls_auth_server_get_type</h4>
<a name="gnutls_005fauth_005fserver_005fget_005ftype"></a><dl>
<dt><a name="index-gnutls_005fauth_005fserver_005fget_005ftype"></a>Function: <em>gnutls_credentials_type_t</em> <strong>gnutls_auth_server_get_type</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Returns the type of credentials that were used for server authentication.
The returned information is to be used to distinguish the function used
to access authentication data.
</p>
<p><strong>Returns:</strong> The type of credentials for the server authentication
schema, a <code>gnutls_credentials_type_t</code>  type.
</p></dd></dl>

<a name="gnutls_005fbuffer_005fappend_005fdata-1"></a>
<h4 class="subheading">gnutls_buffer_append_data</h4>
<a name="gnutls_005fbuffer_005fappend_005fdata"></a><dl>
<dt><a name="index-gnutls_005fbuffer_005fappend_005fdata"></a>Function: <em>int</em> <strong>gnutls_buffer_append_data</strong> <em>(gnutls_buffer_t <var>dest</var>, const void * <var>data</var>, size_t <var>data_size</var>)</em></dt>
<dd><p><var>dest</var>: the buffer to append to
</p>
<p><var>data</var>: the data
</p>
<p><var>data_size</var>: the size of  <code>data</code> 
</p>
<p>Appends the provided  <code>data</code> to the destination buffer.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fbye-1"></a>
<h4 class="subheading">gnutls_bye</h4>
<a name="gnutls_005fbye"></a><dl>
<dt><a name="index-gnutls_005fbye-1"></a>Function: <em>int</em> <strong>gnutls_bye</strong> <em>(gnutls_session_t <var>session</var>, gnutls_close_request_t <var>how</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>how</var>: is an integer
</p>
<p>Terminates the current TLS/SSL connection. The connection should
have been initiated using <code>gnutls_handshake()</code> .   <code>how</code> should be one
of <code>GNUTLS_SHUT_RDWR</code> , <code>GNUTLS_SHUT_WR</code> .
</p>
<p>In case of <code>GNUTLS_SHUT_RDWR</code>  the TLS session gets
terminated and further receives and sends will be disallowed.  If
the return value is zero you may continue using the underlying
transport layer. <code>GNUTLS_SHUT_RDWR</code>  sends an alert containing a close
request and waits for the peer to reply with the same message.
</p>
<p>In case of <code>GNUTLS_SHUT_WR</code>  the TLS session gets terminated
and further sends will be disallowed. In order to reuse the
connection you should wait for an EOF from the peer.
<code>GNUTLS_SHUT_WR</code>  sends an alert containing a close request.
</p>
<p>Note that not all implementations will properly terminate a TLS
connection.  Some of them, usually for performance reasons, will
terminate only the underlying transport layer, and thus not
distinguishing between a malicious party prematurely terminating 
the connection and normal termination. 
</p>
<p>This function may also return <code>GNUTLS_E_AGAIN</code>  or
<code>GNUTLS_E_INTERRUPTED</code> ; cf.  <code>gnutls_record_get_direction()</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code, see
function documentation for entire semantics.
</p></dd></dl>

<a name="gnutls_005fcertificate_005factivation_005ftime_005fpeers-1"></a>
<h4 class="subheading">gnutls_certificate_activation_time_peers</h4>
<a name="gnutls_005fcertificate_005factivation_005ftime_005fpeers"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005factivation_005ftime_005fpeers"></a>Function: <em>time_t</em> <strong>gnutls_certificate_activation_time_peers</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p>This function will return the peer&rsquo;s certificate activation time.
This is the creation time for openpgp keys.
</p>
<p><strong>Returns:</strong> (time_t)-1 on error.
</p>
<p><strong>Deprecated:</strong> <code>gnutls_certificate_verify_peers2()</code>  now verifies activation times.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fallocate_005fcredentials-1"></a>
<h4 class="subheading">gnutls_certificate_allocate_credentials</h4>
<a name="gnutls_005fcertificate_005fallocate_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fallocate_005fcredentials"></a>Function: <em>int</em> <strong>gnutls_certificate_allocate_credentials</strong> <em>(gnutls_certificate_credentials_t *      <var>res</var>)</em></dt>
<dd><p><var>res</var>: is a pointer to a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus this
helper function is provided in order to allocate it.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fclient_005fget_005frequest_005fstatus-1"></a>
<h4 class="subheading">gnutls_certificate_client_get_request_status</h4>
<a name="gnutls_005fcertificate_005fclient_005fget_005frequest_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fclient_005fget_005frequest_005fstatus"></a>Function: <em>int</em> <strong>gnutls_certificate_client_get_request_status</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p>Get whether client certificate is requested or not.
</p>
<p><strong>Returns:</strong> 0 if the peer (server) did not request client
authentication or 1 otherwise.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fexpiration_005ftime_005fpeers-1"></a>
<h4 class="subheading">gnutls_certificate_expiration_time_peers</h4>
<a name="gnutls_005fcertificate_005fexpiration_005ftime_005fpeers"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fexpiration_005ftime_005fpeers"></a>Function: <em>time_t</em> <strong>gnutls_certificate_expiration_time_peers</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p>This function will return the peer&rsquo;s certificate expiration time.
</p>
<p><strong>Returns:</strong> (time_t)-1 on error.
</p>
<p><strong>Deprecated:</strong> <code>gnutls_certificate_verify_peers2()</code>  now verifies expiration times.
</p></dd></dl>

<a name="gnutls_005fcertificate_005ffree_005fca_005fnames-1"></a>
<h4 class="subheading">gnutls_certificate_free_ca_names</h4>
<a name="gnutls_005fcertificate_005ffree_005fca_005fnames"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005ffree_005fca_005fnames"></a>Function: <em>void</em> <strong>gnutls_certificate_free_ca_names</strong> <em>(gnutls_certificate_credentials_t <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p>This function will delete all the CA name in the given
credentials. Clients may call this to save some memory since in
client side the CA names are not used. Servers might want to use
this function if a large list of trusted CAs is present and
sending the names of it would just consume bandwidth without providing 
information to client.
</p>
<p>CA names are used by servers to advertise the CAs they support to
clients.
</p></dd></dl>

<a name="gnutls_005fcertificate_005ffree_005fcas-1"></a>
<h4 class="subheading">gnutls_certificate_free_cas</h4>
<a name="gnutls_005fcertificate_005ffree_005fcas"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005ffree_005fcas"></a>Function: <em>void</em> <strong>gnutls_certificate_free_cas</strong> <em>(gnutls_certificate_credentials_t <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p>This function will delete all the CAs associated with the given
credentials. Servers that do not use
<code>gnutls_certificate_verify_peers2()</code>  may call this to save some
memory.
</p></dd></dl>

<a name="gnutls_005fcertificate_005ffree_005fcredentials-1"></a>
<h4 class="subheading">gnutls_certificate_free_credentials</h4>
<a name="gnutls_005fcertificate_005ffree_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005ffree_005fcredentials"></a>Function: <em>void</em> <strong>gnutls_certificate_free_credentials</strong> <em>(gnutls_certificate_credentials_t <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus this
helper function is provided in order to free (deallocate) it.
</p>
<p>This function does not free any temporary parameters associated
with this structure (ie RSA and DH parameters are not freed by this
function).
</p></dd></dl>

<a name="gnutls_005fcertificate_005ffree_005fcrls-1"></a>
<h4 class="subheading">gnutls_certificate_free_crls</h4>
<a name="gnutls_005fcertificate_005ffree_005fcrls"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005ffree_005fcrls"></a>Function: <em>void</em> <strong>gnutls_certificate_free_crls</strong> <em>(gnutls_certificate_credentials_t <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p>This function will delete all the CRLs associated
with the given credentials.
</p></dd></dl>

<a name="gnutls_005fcertificate_005ffree_005fkeys-1"></a>
<h4 class="subheading">gnutls_certificate_free_keys</h4>
<a name="gnutls_005fcertificate_005ffree_005fkeys"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005ffree_005fkeys"></a>Function: <em>void</em> <strong>gnutls_certificate_free_keys</strong> <em>(gnutls_certificate_credentials_t <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p>This function will delete all the keys and the certificates associated
with the given credentials. This function must not be called when a
TLS negotiation that uses the credentials is in progress.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fget_005fcrt_005fraw-1"></a>
<h4 class="subheading">gnutls_certificate_get_crt_raw</h4>
<a name="gnutls_005fcertificate_005fget_005fcrt_005fraw"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fget_005fcrt_005fraw"></a>Function: <em>int</em> <strong>gnutls_certificate_get_crt_raw</strong> <em>(gnutls_certificate_credentials_t <var>sc</var>, unsigned <var>idx1</var>, unsigned <var>idx2</var>, gnutls_datum_t * <var>cert</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>idx1</var>: the index of the certificate if multiple are present
</p>
<p><var>idx2</var>: the index in the certificate list. Zero gives the server&rsquo;s certificate.
</p>
<p><var>cert</var>: Will hold the DER encoded certificate.
</p>
<p>This function will return the DER encoded certificate of the
server or any other certificate on its certificate chain (based on  <code>idx2</code> ).
The returned data should be treated as constant and only accessible during the lifetime
of  <code>sc</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. In case the indexes are out of bounds <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
is returned.
</p>
<p><strong>Since:</strong> 3.2.5
</p></dd></dl>

<a name="gnutls_005fcertificate_005fget_005fissuer-1"></a>
<h4 class="subheading">gnutls_certificate_get_issuer</h4>
<a name="gnutls_005fcertificate_005fget_005fissuer"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fget_005fissuer"></a>Function: <em>int</em> <strong>gnutls_certificate_get_issuer</strong> <em>(gnutls_certificate_credentials_t <var>sc</var>, gnutls_x509_crt_t <var>cert</var>, gnutls_x509_crt_t * <var>issuer</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>cert</var>: is the certificate to find issuer for
</p>
<p><var>issuer</var>: Will hold the issuer if any. Should be treated as constant.
</p>
<p><var>flags</var>: Use zero or <code>GNUTLS_TL_GET_COPY</code> 
</p>
<p>This function will return the issuer of a given certificate.
As with <code>gnutls_x509_trust_list_get_issuer()</code>  this function requires
the <code>GNUTLS_TL_GET_COPY</code>  flag in order to operate with PKCS <code>11</code>  trust
lists. In that case the issuer must be freed using <code>gnutls_x509_crt_deinit()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fget_005fours-1"></a>
<h4 class="subheading">gnutls_certificate_get_ours</h4>
<a name="gnutls_005fcertificate_005fget_005fours"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fget_005fours"></a>Function: <em>const gnutls_datum_t *</em> <strong>gnutls_certificate_get_ours</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p>Gets the certificate as sent to the peer in the last handshake.
The certificate is in raw (DER) format.  No certificate
list is being returned. Only the first certificate.
</p>
<p><strong>Returns:</strong> a pointer to a <code>gnutls_datum_t</code>  containing our
certificate, or <code>NULL</code>  in case of an error or if no certificate
was used.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fget_005fpeers-1"></a>
<h4 class="subheading">gnutls_certificate_get_peers</h4>
<a name="gnutls_005fcertificate_005fget_005fpeers"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fget_005fpeers"></a>Function: <em>const gnutls_datum_t *</em> <strong>gnutls_certificate_get_peers</strong> <em>(gnutls_session_t          <var>session</var>, unsigned int * <var>list_size</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p><var>list_size</var>: is the length of the certificate list (may be <code>NULL</code> )
</p>
<p>Get the peer&rsquo;s raw certificate (chain) as sent by the peer.  These
certificates are in raw format (DER encoded for X.509).  In case of
a X.509 then a certificate list may be present.  The first
certificate in the list is the peer&rsquo;s certificate, following the
issuer&rsquo;s certificate, then the issuer&rsquo;s issuer etc.
</p>
<p>In case of OpenPGP keys a single key will be returned in raw
format.
</p>
<p><strong>Returns:</strong> a pointer to a <code>gnutls_datum_t</code>  containing the peer&rsquo;s
certificates, or <code>NULL</code>  in case of an error or if no certificate
was used.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fget_005fpeers_005fsubkey_005fid-1"></a>
<h4 class="subheading">gnutls_certificate_get_peers_subkey_id</h4>
<a name="gnutls_005fcertificate_005fget_005fpeers_005fsubkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fget_005fpeers_005fsubkey_005fid"></a>Function: <em>int</em> <strong>gnutls_certificate_get_peers_subkey_id</strong> <em>(gnutls_session_t <var>session</var>, gnutls_datum_t * <var>id</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p><var>id</var>: will contain the ID
</p>
<p>Get the peer&rsquo;s subkey ID when OpenPGP certificates are
used. The returned  <code>id</code> should be treated as constant.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fcertificate_005fget_005fverify_005fflags-1"></a>
<h4 class="subheading">gnutls_certificate_get_verify_flags</h4>
<a name="gnutls_005fcertificate_005fget_005fverify_005fflags"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fget_005fverify_005fflags"></a>Function: <em>unsigned int</em> <strong>gnutls_certificate_get_verify_flags</strong> <em>(gnutls_certificate_credentials_t <var>res</var>)</em></dt>
<dd><p><var>res</var>: is a gnutls_certificate_credentials_t type
</p>
<p>Returns the verification flags set with
<code>gnutls_certificate_set_verify_flags()</code> .
</p>
<p><strong>Returns:</strong> The certificate verification flags used by  <code>res</code> .
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fget_005fx509_005fcrt-1"></a>
<h4 class="subheading">gnutls_certificate_get_x509_crt</h4>
<a name="gnutls_005fcertificate_005fget_005fx509_005fcrt"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fget_005fx509_005fcrt"></a>Function: <em>int</em> <strong>gnutls_certificate_get_x509_crt</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, unsigned <var>index</var>, gnutls_x509_crt_t ** <var>crt_list</var>, unsigned * <var>crt_list_size</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>index</var>: The index of the certificate list to obtain.
</p>
<p><var>crt_list</var>: Where to store the certificate list.
</p>
<p><var>crt_list_size</var>: Will hold the number of certificates.
</p>
<p>Obtains a X.509 certificate list that has been stored in  <code>res</code> with one of
<code>gnutls_certificate_set_x509_key()</code> , <code>gnutls_certificate_set_key()</code> ,
<code>gnutls_certificate_set_x509_key_file()</code> ,
<code>gnutls_certificate_set_x509_key_file2()</code> ,
<code>gnutls_certificate_set_x509_key_mem()</code> , or
<code>gnutls_certificate_set_x509_key_mem2()</code> . Each certificate in the returned
certificate list must be deallocated with <code>gnutls_x509_crt_deinit()</code> , and the
list itself must be freed with <code>gnutls_free()</code> .
</p>
<p>If there is no certificate with the given index,
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned. If the certificate
with the given index is not a X.509 certificate, <code>GNUTLS_E_INVALID_REQUEST</code> 
is returned. The returned certificates must be deinitialized after
use, and the  <code>crt_list</code> pointer must be freed using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fget_005fx509_005fkey-1"></a>
<h4 class="subheading">gnutls_certificate_get_x509_key</h4>
<a name="gnutls_005fcertificate_005fget_005fx509_005fkey"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fget_005fx509_005fkey"></a>Function: <em>int</em> <strong>gnutls_certificate_get_x509_key</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, unsigned <var>index</var>, gnutls_x509_privkey_t * <var>key</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>index</var>: The index of the key to obtain.
</p>
<p><var>key</var>: Location to store the key.
</p>
<p>Obtains a X.509 private key that has been stored in  <code>res</code> with one of
<code>gnutls_certificate_set_x509_key()</code> , <code>gnutls_certificate_set_key()</code> ,
<code>gnutls_certificate_set_x509_key_file()</code> ,
<code>gnutls_certificate_set_x509_key_file2()</code> ,
<code>gnutls_certificate_set_x509_key_mem()</code> , or
<code>gnutls_certificate_set_x509_key_mem2()</code> . The returned key must be deallocated
with <code>gnutls_x509_privkey_deinit()</code>  when no longer needed.
</p>
<p>If there is no key with the given index,
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned. If the key with the
given index is not a X.509 key, <code>GNUTLS_E_INVALID_REQUEST</code>  is returned.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fsend_005fx509_005frdn_005fsequence-1"></a>
<h4 class="subheading">gnutls_certificate_send_x509_rdn_sequence</h4>
<a name="gnutls_005fcertificate_005fsend_005fx509_005frdn_005fsequence"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fsend_005fx509_005frdn_005fsequence-1"></a>Function: <em>void</em> <strong>gnutls_certificate_send_x509_rdn_sequence</strong> <em>(gnutls_session_t <var>session</var>, int <var>status</var>)</em></dt>
<dd><p><var>session</var>: a <code>gnutls_session_t</code>  type.
</p>
<p><var>status</var>: is 0 or 1
</p>
<p>If status is non zero, this function will order gnutls not to send
the rdnSequence in the certificate request message. That is the
server will not advertise its trusted CAs to the peer. If status
is zero then the default behaviour will take effect, which is to
advertise the server&rsquo;s trusted CAs.
</p>
<p>This function has no effect in clients, and in authentication
methods other than certificate with X.509 certificates.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fserver_005fset_005frequest-1"></a>
<h4 class="subheading">gnutls_certificate_server_set_request</h4>
<a name="gnutls_005fcertificate_005fserver_005fset_005frequest"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fserver_005fset_005frequest-1"></a>Function: <em>void</em> <strong>gnutls_certificate_server_set_request</strong> <em>(gnutls_session_t <var>session</var>, gnutls_certificate_request_t <var>req</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>req</var>: is one of GNUTLS_CERT_REQUEST, GNUTLS_CERT_REQUIRE
</p>
<p>This function specifies if we (in case of a server) are going to
send a certificate request message to the client. If  <code>req</code> is
GNUTLS_CERT_REQUIRE then the server will return an error if the
peer does not provide a certificate. If you do not call this
function then the client will not be asked to send a certificate.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fdh_005fparams-1"></a>
<h4 class="subheading">gnutls_certificate_set_dh_params</h4>
<a name="gnutls_005fcertificate_005fset_005fdh_005fparams"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fdh_005fparams"></a>Function: <em>void</em> <strong>gnutls_certificate_set_dh_params</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, gnutls_dh_params_t <var>dh_params</var>)</em></dt>
<dd><p><var>res</var>: is a gnutls_certificate_credentials_t type
</p>
<p><var>dh_params</var>: the Diffie-Hellman parameters.
</p>
<p>This function will set the Diffie-Hellman parameters for a
certificate server to use. These parameters will be used in
Ephemeral Diffie-Hellman cipher suites.  Note that only a pointer
to the parameters are stored in the certificate handle, so you
must not deallocate the parameters before the certificate is deallocated.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fflags-1"></a>
<h4 class="subheading">gnutls_certificate_set_flags</h4>
<a name="gnutls_005fcertificate_005fset_005fflags"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fflags"></a>Function: <em>void</em> <strong>gnutls_certificate_set_flags</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>res</var>: is a gnutls_certificate_credentials_t type
</p>
<p><var>flags</var>: are the flags of <code>gnutls_certificate_flags</code>  type
</p>
<p>This function will set flags to tweak the operation of
the credentials structure. See the <code>gnutls_certificate_flags</code>  enumerations
for more information on the available flags. 
</p>
<p><strong>Since:</strong> 3.4.7
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005focsp_005fstatus_005frequest_005ffile-1"></a>
<h4 class="subheading">gnutls_certificate_set_ocsp_status_request_file</h4>
<a name="gnutls_005fcertificate_005fset_005focsp_005fstatus_005frequest_005ffile"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005focsp_005fstatus_005frequest_005ffile"></a>Function: <em>int</em> <strong>gnutls_certificate_set_ocsp_status_request_file</strong> <em>(gnutls_certificate_credentials_t <var>sc</var>, const char * <var>response_file</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>sc</var>: is a credentials structure.
</p>
<p><var>response_file</var>: a filename of the OCSP response
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function sets the filename of an OCSP response, that will be
sent to the client if requests an OCSP certificate status. This is
a convenience function which is inefficient on busy servers since
the file is opened on every access. Use 
<code>gnutls_certificate_set_ocsp_status_request_function()</code>  to fine-tune
file accesses.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005focsp_005fstatus_005frequest_005ffunction-1"></a>
<h4 class="subheading">gnutls_certificate_set_ocsp_status_request_function</h4>
<a name="gnutls_005fcertificate_005fset_005focsp_005fstatus_005frequest_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005focsp_005fstatus_005frequest_005ffunction"></a>Function: <em>void</em> <strong>gnutls_certificate_set_ocsp_status_request_function</strong> <em>(gnutls_certificate_credentials_t <var>sc</var>, gnutls_status_request_ocsp_func <var>ocsp_func</var>, void * <var>ptr</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>ocsp_func</var>: function pointer to OCSP status request callback.
</p>
<p><var>ptr</var>: opaque pointer passed to callback function
</p>
<p>This function is to be used by server to register a callback to
handle OCSP status requests from the client.  The callback will be
invoked if the client supplied a status-request OCSP extension.
The callback function prototype is:
</p>
<p>typedef int (*gnutls_status_request_ocsp_func)
(gnutls_session_t session, void *ptr, gnutls_datum_t *ocsp_response);
</p>
<p>The callback will be invoked if the client requests an OCSP certificate
status.  The callback may return <code>GNUTLS_E_NO_CERTIFICATE_STATUS</code> , if
there is no recent OCSP response. If the callback returns <code>GNUTLS_E_SUCCESS</code> ,
the server will provide the client with the ocsp_response.
</p>
<p>The response must be a value allocated using <code>gnutls_malloc()</code> , and will be
deinitialized when needed.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fparams_005ffunction-1"></a>
<h4 class="subheading">gnutls_certificate_set_params_function</h4>
<a name="gnutls_005fcertificate_005fset_005fparams_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fparams_005ffunction-1"></a>Function: <em>void</em> <strong>gnutls_certificate_set_params_function</strong> <em>(gnutls_certificate_credentials_t            <var>res</var>, gnutls_params_function * <var>func</var>)</em></dt>
<dd><p><var>res</var>: is a gnutls_certificate_credentials_t type
</p>
<p><var>func</var>: is the function to be called
</p>
<p>This function will set a callback in order for the server to get
the Diffie-Hellman or RSA parameters for certificate
authentication.  The callback should return <code>GNUTLS_E_SUCCESS</code>  (0) on success.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fpin_005ffunction-1"></a>
<h4 class="subheading">gnutls_certificate_set_pin_function</h4>
<a name="gnutls_005fcertificate_005fset_005fpin_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fpin_005ffunction-1"></a>Function: <em>void</em> <strong>gnutls_certificate_set_pin_function</strong> <em>(gnutls_certificate_credentials_t       <var>cred</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>fn</var>: A PIN callback
</p>
<p><var>userdata</var>: Data to be passed in the callback
</p>
<p>This function will set a callback function to be used when
required to access a protected object. This function overrides any other
global PIN functions.
</p>
<p>Note that this function must be called right after initialization
to have effect.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fretrieve_005ffunction-1"></a>
<h4 class="subheading">gnutls_certificate_set_retrieve_function</h4>
<a name="gnutls_005fcertificate_005fset_005fretrieve_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fretrieve_005ffunction"></a>Function: <em>void</em> <strong>gnutls_certificate_set_retrieve_function</strong> <em>(gnutls_certificate_credentials_t <var>cred</var>, gnutls_certificate_retrieve_function * <var>func</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>func</var>: is the callback function
</p>
<p>This function sets a callback to be called in order to retrieve the
certificate to be used in the handshake. The callback will take control
only if a certificate is requested by the peer. You are advised
to use <code>gnutls_certificate_set_retrieve_function2()</code>  because it
is much more efficient in the processing it requires from gnutls.
</p>
<p>The callback&rsquo;s function prototype is:
int (*callback)(gnutls_session_t, const gnutls_datum_t* req_ca_dn, int nreqs,
const gnutls_pk_algorithm_t* pk_algos, int pk_algos_length, gnutls_retr2_st* st);
</p>
<p><code>req_ca_dn</code> is only used in X.509 certificates.
Contains a list with the CA names that the server considers trusted.
This is a hint and typically the client should send a certificate that is signed
by one of these CAs. These names, when available, are DER encoded. To get a more
meaningful value use the function <code>gnutls_x509_rdn_get()</code> .
</p>
<p><code>pk_algos</code> contains a list with server&rsquo;s acceptable signature algorithms.
The certificate returned should support the server&rsquo;s given algorithms.
</p>
<p><code>st</code> should contain the certificates and private keys.
</p>
<p>If the callback function is provided then gnutls will call it, in the
handshake, after the certificate request message has been received.
</p>
<p>In server side pk_algos and req_ca_dn are NULL.
</p>
<p>The callback function should set the certificate list to be sent,
and return 0 on success. If no certificate was selected then the
number of certificates should be set to zero. The value (-1)
indicates error and the handshake will be terminated. If both certificates
are set in the credentials and a callback is available, the callback
takes predence.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fverify_005fflags-1"></a>
<h4 class="subheading">gnutls_certificate_set_verify_flags</h4>
<a name="gnutls_005fcertificate_005fset_005fverify_005fflags"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fverify_005fflags"></a>Function: <em>void</em> <strong>gnutls_certificate_set_verify_flags</strong> <em>(gnutls_certificate_credentials_t         <var>res</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>res</var>: is a gnutls_certificate_credentials_t type
</p>
<p><var>flags</var>: are the flags
</p>
<p>This function will set the flags to be used for verification 
of certificates and override any defaults.  The provided flags must be an OR of the
<code>gnutls_certificate_verify_flags</code>  enumerations. 
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fverify_005ffunction-1"></a>
<h4 class="subheading">gnutls_certificate_set_verify_function</h4>
<a name="gnutls_005fcertificate_005fset_005fverify_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fverify_005ffunction"></a>Function: <em>void</em> <strong>gnutls_certificate_set_verify_function</strong> <em>(gnutls_certificate_credentials_t <var>cred</var>, gnutls_certificate_verify_function * <var>func</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>func</var>: is the callback function
</p>
<p>This function sets a callback to be called when peer&rsquo;s certificate
has been received in order to verify it on receipt rather than
doing after the handshake is completed.
</p>
<p>The callback&rsquo;s function prototype is:
int (*callback)(gnutls_session_t);
</p>
<p>If the callback function is provided then gnutls will call it, in the
handshake, just after the certificate message has been received.
To verify or obtain the certificate the <code>gnutls_certificate_verify_peers2()</code> ,
<code>gnutls_certificate_type_get()</code> , <code>gnutls_certificate_get_peers()</code>  functions
can be used.
</p>
<p>The callback function should return 0 for the handshake to continue
or non-zero to terminate.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fverify_005flimits-1"></a>
<h4 class="subheading">gnutls_certificate_set_verify_limits</h4>
<a name="gnutls_005fcertificate_005fset_005fverify_005flimits"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fverify_005flimits"></a>Function: <em>void</em> <strong>gnutls_certificate_set_verify_limits</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, unsigned int <var>max_bits</var>, unsigned int <var>max_depth</var>)</em></dt>
<dd><p><var>res</var>: is a gnutls_certificate_credentials type
</p>
<p><var>max_bits</var>: is the number of bits of an acceptable certificate (default 8200)
</p>
<p><var>max_depth</var>: is maximum depth of the verification of a certificate chain (default 5)
</p>
<p>This function will set some upper limits for the default
verification function, <code>gnutls_certificate_verify_peers2()</code> , to avoid
denial of service attacks.  You can set them to zero to disable
limits.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005fcrl-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_crl</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005fcrl"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005fcrl"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_crl</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, gnutls_x509_crl_t * <var>crl_list</var>, int <var>crl_list_size</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>crl_list</var>: is a list of trusted CRLs. They should have been verified before.
</p>
<p><var>crl_list_size</var>: holds the size of the crl_list
</p>
<p>This function adds the trusted CRLs in order to verify client or
server certificates.  In case of a client this is not required to
be called if the certificates are not verified using
<code>gnutls_certificate_verify_peers2()</code> .  This function may be called
multiple times.
</p>
<p><strong>Returns:</strong> number of CRLs processed, or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005fcrl_005ffile-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_crl_file</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005fcrl_005ffile"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005fcrl_005ffile"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_crl_file</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, const char * <var>crlfile</var>, gnutls_x509_crt_fmt_t <var>type</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>crlfile</var>: is a file containing the list of verified CRLs (DER or PEM list)
</p>
<p><var>type</var>: is PEM or DER
</p>
<p>This function adds the trusted CRLs in order to verify client or server
certificates.  In case of a client this is not required
to be called if the certificates are not verified using
<code>gnutls_certificate_verify_peers2()</code> .
This function may be called multiple times.
</p>
<p><strong>Returns:</strong> number of CRLs processed or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005fcrl_005fmem-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_crl_mem</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005fcrl_005fmem"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005fcrl_005fmem"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_crl_mem</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, const gnutls_datum_t * <var>CRL</var>, gnutls_x509_crt_fmt_t <var>type</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>CRL</var>: is a list of trusted CRLs. They should have been verified before.
</p>
<p><var>type</var>: is DER or PEM
</p>
<p>This function adds the trusted CRLs in order to verify client or
server certificates.  In case of a client this is not required to
be called if the certificates are not verified using
<code>gnutls_certificate_verify_peers2()</code> .  This function may be called
multiple times.
</p>
<p><strong>Returns:</strong> number of CRLs processed, or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005fkey-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_key</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005fkey"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005fkey"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_key</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, gnutls_x509_crt_t * <var>cert_list</var>, int <var>cert_list_size</var>, gnutls_x509_privkey_t <var>key</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>cert_list</var>: contains a certificate list (path) for the specified private key
</p>
<p><var>cert_list_size</var>: holds the size of the certificate list
</p>
<p><var>key</var>: is a <code>gnutls_x509_privkey_t</code>  key
</p>
<p>This function sets a certificate/private key pair in the
gnutls_certificate_credentials_t type.  This function may be
called more than once, in case multiple keys/certificates exist for
the server.  For clients that wants to send more than their own end
entity certificate (e.g., also an intermediate CA cert) then put
the certificate chain in  <code>cert_list</code> .
</p>
<p>Note that the certificates and keys provided, can be safely deinitialized
after this function is called.
</p>
<p>If that function fails to load the  <code>res</code> type is at an undefined state, it must
not be reused to load other keys or certificates.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_key_file</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_key_file</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, const char * <var>certfile</var>, const char * <var>keyfile</var>, gnutls_x509_crt_fmt_t <var>type</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>certfile</var>: is a file that containing the certificate list (path) for
the specified private key, in PKCS7 format, or a list of certificates
</p>
<p><var>keyfile</var>: is a file that contains the private key
</p>
<p><var>type</var>: is PEM or DER
</p>
<p>This function sets a certificate/private key pair in the
gnutls_certificate_credentials_t type.  This function may be
called more than once, in case multiple keys/certificates exist for
the server.  For clients that need to send more than its own end
entity certificate, e.g., also an intermediate CA cert, then the
 <code>certfile</code> must contain the ordered certificate chain.
</p>
<p>Note that the names in the certificate provided will be considered
when selecting the appropriate certificate to use (in case of multiple
certificate/key pairs).
</p>
<p>This function can also accept URLs at  <code>keyfile</code> and  <code>certfile</code> . In that case it
will use the private key and certificate indicated by the URLs. Note
that the supported URLs are the ones indicated by <code>gnutls_url_is_supported()</code> .
</p>
<p>In case the  <code>certfile</code> is provided as a PKCS <code>11</code>  URL, then the certificate, and its
present issuers in the token are imported (i.e., forming the required trust chain).
</p>
<p>If that function fails to load the  <code>res</code> structure is at an undefined state, it must
not be reused to load other keys or certificates.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p>
<p><strong>Since:</strong> 3.1.11
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile2-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_key_file2</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile2"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile2"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_key_file2</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, const char * <var>certfile</var>, const char * <var>keyfile</var>, gnutls_x509_crt_fmt_t <var>type</var>, const char * <var>pass</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>certfile</var>: is a file that containing the certificate list (path) for
the specified private key, in PKCS7 format, or a list of certificates
</p>
<p><var>keyfile</var>: is a file that contains the private key
</p>
<p><var>type</var>: is PEM or DER
</p>
<p><var>pass</var>: is the password of the key
</p>
<p><var>flags</var>: an ORed sequence of gnutls_pkcs_encrypt_flags_t
</p>
<p>This function sets a certificate/private key pair in the
gnutls_certificate_credentials_t type.  This function may be
called more than once, in case multiple keys/certificates exist for
the server.  For clients that need to send more than its own end
entity certificate, e.g., also an intermediate CA cert, then the
 <code>certfile</code> must contain the ordered certificate chain.
</p>
<p>Note that the names in the certificate provided will be considered
when selecting the appropriate certificate to use (in case of multiple
certificate/key pairs).
</p>
<p>This function can also accept URLs at  <code>keyfile</code> and  <code>certfile</code> . In that case it
will use the private key and certificate indicated by the URLs. Note
that the supported URLs are the ones indicated by <code>gnutls_url_is_supported()</code> .
Before GnuTLS 3.4.0 when a URL was specified, the  <code>pass</code> part was ignored and a
PIN callback had to be registered, this is no longer the case in current releases.
</p>
<p>In case the  <code>certfile</code> is provided as a PKCS <code>11</code>  URL, then the certificate, and its
present issuers in the token are imported (i.e., forming the required trust chain).
</p>
<p>If that function fails to load the  <code>res</code> structure is at an undefined state, it must
not be reused to load other keys or certificates.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005fkey_005fmem-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_key_mem</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005fkey_005fmem"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005fkey_005fmem"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_key_mem</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, const gnutls_datum_t * <var>cert</var>, const gnutls_datum_t * <var>key</var>, gnutls_x509_crt_fmt_t <var>type</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>cert</var>: contains a certificate list (path) for the specified private key
</p>
<p><var>key</var>: is the private key, or <code>NULL</code> 
</p>
<p><var>type</var>: is PEM or DER
</p>
<p>This function sets a certificate/private key pair in the
gnutls_certificate_credentials_t type. This function may be called
more than once, in case multiple keys/certificates exist for the
server.
</p>
<p>Note that the keyUsage (2.5.29.15) PKIX extension in X.509 certificates
is supported. This means that certificates intended for signing cannot
be used for ciphersuites that require encryption.
</p>
<p>If the certificate and the private key are given in PEM encoding
then the strings that hold their values must be null terminated.
</p>
<p>The  <code>key</code> may be <code>NULL</code>  if you are using a sign callback, see
<code>gnutls_sign_callback_set()</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005fkey_005fmem2-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_key_mem2</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005fkey_005fmem2"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005fkey_005fmem2"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_key_mem2</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, const gnutls_datum_t * <var>cert</var>, const gnutls_datum_t * <var>key</var>, gnutls_x509_crt_fmt_t <var>type</var>, const char * <var>pass</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>cert</var>: contains a certificate list (path) for the specified private key
</p>
<p><var>key</var>: is the private key, or <code>NULL</code> 
</p>
<p><var>type</var>: is PEM or DER
</p>
<p><var>pass</var>: is the key&rsquo;s password
</p>
<p><var>flags</var>: an ORed sequence of gnutls_pkcs_encrypt_flags_t
</p>
<p>This function sets a certificate/private key pair in the
gnutls_certificate_credentials_t type. This function may be called
more than once, in case multiple keys/certificates exist for the
server.
</p>
<p>Note that the keyUsage (2.5.29.15) PKIX extension in X.509 certificates
is supported. This means that certificates intended for signing cannot
be used for ciphersuites that require encryption.
</p>
<p>If the certificate and the private key are given in PEM encoding
then the strings that hold their values must be null terminated.
</p>
<p>The  <code>key</code> may be <code>NULL</code>  if you are using a sign callback, see
<code>gnutls_sign_callback_set()</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005fsimple_005fpkcs12_005ffile-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_simple_pkcs12_file</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005fsimple_005fpkcs12_005ffile"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005fsimple_005fpkcs12_005ffile"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_simple_pkcs12_file</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, const char * <var>pkcs12file</var>, gnutls_x509_crt_fmt_t <var>type</var>, const char * <var>password</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>pkcs12file</var>: filename of file containing PKCS<code>12</code>  blob.
</p>
<p><var>type</var>: is PEM or DER of the  <code>pkcs12file</code> .
</p>
<p><var>password</var>: optional password used to decrypt PKCS<code>12</code>  file, bags and keys.
</p>
<p>This function sets a certificate/private key pair and/or a CRL in
the gnutls_certificate_credentials_t type.  This function may
be called more than once (in case multiple keys/certificates exist
for the server).
</p>
<p>PKCS<code>12</code>  files with a MAC, encrypted bags and PKCS <code>8</code> 
private keys are supported. However,
only password based security, and the same password for all
operations, are supported.
</p>
<p>PKCS<code>12</code>  file may contain many keys and/or certificates, and this
function will try to auto-detect based on the key ID the certificate
and key pair to use. If the PKCS<code>12</code>  file contain the issuer of
the selected certificate, it will be appended to the certificate
to form a chain.
</p>
<p>If more than one private keys are stored in the PKCS<code>12</code>  file,
then only one key will be read (and it is undefined which one).
</p>
<p>It is believed that the limitations of this function is acceptable
for most usage, and that any more flexibility would introduce
complexity that would make it harder to use this functionality at
all.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005fsimple_005fpkcs12_005fmem-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_simple_pkcs12_mem</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005fsimple_005fpkcs12_005fmem"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005fsimple_005fpkcs12_005fmem"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_simple_pkcs12_mem</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, const gnutls_datum_t * <var>p12blob</var>, gnutls_x509_crt_fmt_t <var>type</var>, const char * <var>password</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>p12blob</var>: the PKCS<code>12</code>  blob.
</p>
<p><var>type</var>: is PEM or DER of the  <code>pkcs12file</code> .
</p>
<p><var>password</var>: optional password used to decrypt PKCS<code>12</code>  file, bags and keys.
</p>
<p>This function sets a certificate/private key pair and/or a CRL in
the gnutls_certificate_credentials_t type.  This function may
be called more than once (in case multiple keys/certificates exist
for the server).
</p>
<p>Encrypted PKCS<code>12</code>  bags and PKCS<code>8</code>  private keys are supported.  However,
only password based security, and the same password for all
operations, are supported.
</p>
<p>PKCS<code>12</code>  file may contain many keys and/or certificates, and this
function will try to auto-detect based on the key ID the certificate
and key pair to use. If the PKCS<code>12</code>  file contain the issuer of
the selected certificate, it will be appended to the certificate
to form a chain.
</p>
<p>If more than one private keys are stored in the PKCS<code>12</code>  file,
then only one key will be read (and it is undefined which one).
</p>
<p>It is believed that the limitations of this function is acceptable
for most usage, and that any more flexibility would introduce
complexity that would make it harder to use this functionality at
all.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005fsystem_005ftrust-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_system_trust</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005fsystem_005ftrust"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005fsystem_005ftrust-1"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_system_trust</strong> <em>(gnutls_certificate_credentials_t       <var>cred</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p>This function adds the system&rsquo;s default trusted CAs in order to
verify client or server certificates.
</p>
<p>In the case the system is currently unsupported <code>GNUTLS_E_UNIMPLEMENTED_FEATURE</code> 
is returned.
</p>
<p><strong>Returns:</strong> the number of certificates processed or a negative error code
on error.
</p>
<p><strong>Since:</strong> 3.0.20
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005ftrust-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_trust</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005ftrust"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005ftrust"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_trust</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, gnutls_x509_crt_t * <var>ca_list</var>, int <var>ca_list_size</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>ca_list</var>: is a list of trusted CAs
</p>
<p><var>ca_list_size</var>: holds the size of the CA list
</p>
<p>This function adds the trusted CAs in order to verify client
or server certificates. In case of a client this is not required
to be called if the certificates are not verified using
<code>gnutls_certificate_verify_peers2()</code> .
This function may be called multiple times.
</p>
<p>In case of a server the CAs set here will be sent to the client if
a certificate request is sent. This can be disabled using
<code>gnutls_certificate_send_x509_rdn_sequence()</code> .
</p>
<p><strong>Returns:</strong> the number of certificates processed or a negative error code
on error.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005ftrust_005fdir-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_trust_dir</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005ftrust_005fdir"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005ftrust_005fdir"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_trust_dir</strong> <em>(gnutls_certificate_credentials_t <var>cred</var>, const char * <var>ca_dir</var>, gnutls_x509_crt_fmt_t <var>type</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>ca_dir</var>: is a directory containing the list of trusted CAs (DER or PEM list)
</p>
<p><var>type</var>: is PEM or DER
</p>
<p>This function adds the trusted CAs present in the directory in order to 
verify client or server certificates. This function is identical
to <code>gnutls_certificate_set_x509_trust_file()</code>  but loads all certificates
in a directory.
</p>
<p><strong>Returns:</strong> the number of certificates processed
</p>
<p><strong>Since:</strong> 3.3.6
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005ftrust_005ffile-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_trust_file</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005ftrust_005ffile"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005ftrust_005ffile"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_trust_file</strong> <em>(gnutls_certificate_credentials_t            <var>cred</var>, const char * <var>cafile</var>, gnutls_x509_crt_fmt_t <var>type</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>cafile</var>: is a file containing the list of trusted CAs (DER or PEM list)
</p>
<p><var>type</var>: is PEM or DER
</p>
<p>This function adds the trusted CAs in order to verify client or
server certificates. In case of a client this is not required to
be called if the certificates are not verified using
<code>gnutls_certificate_verify_peers2()</code> .  This function may be called
multiple times.
</p>
<p>In case of a server the names of the CAs set here will be sent to
the client if a certificate request is sent. This can be disabled
using <code>gnutls_certificate_send_x509_rdn_sequence()</code> .
</p>
<p>This function can also accept URLs. In that case it
will import all certificates that are marked as trusted. Note
that the supported URLs are the ones indicated by <code>gnutls_url_is_supported()</code> .
</p>
<p><strong>Returns:</strong> the number of certificates processed
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fx509_005ftrust_005fmem-1"></a>
<h4 class="subheading">gnutls_certificate_set_x509_trust_mem</h4>
<a name="gnutls_005fcertificate_005fset_005fx509_005ftrust_005fmem"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fx509_005ftrust_005fmem"></a>Function: <em>int</em> <strong>gnutls_certificate_set_x509_trust_mem</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, const gnutls_datum_t * <var>ca</var>, gnutls_x509_crt_fmt_t <var>type</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>ca</var>: is a list of trusted CAs or a DER certificate
</p>
<p><var>type</var>: is DER or PEM
</p>
<p>This function adds the trusted CAs in order to verify client or
server certificates. In case of a client this is not required to be
called if the certificates are not verified using
<code>gnutls_certificate_verify_peers2()</code> .  This function may be called
multiple times.
</p>
<p>In case of a server the CAs set here will be sent to the client if
a certificate request is sent. This can be disabled using
<code>gnutls_certificate_send_x509_rdn_sequence()</code> .
</p>
<p><strong>Returns:</strong> the number of certificates processed or a negative error code
on error.
</p></dd></dl>

<a name="gnutls_005fcertificate_005ftype_005fget-1"></a>
<h4 class="subheading">gnutls_certificate_type_get</h4>
<a name="gnutls_005fcertificate_005ftype_005fget"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005ftype_005fget"></a>Function: <em>gnutls_certificate_type_t</em> <strong>gnutls_certificate_type_get</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>The certificate type is by default X.509, unless it is negotiated
as a TLS extension.
</p>
<p><strong>Returns:</strong> the currently used <code>gnutls_certificate_type_t</code>  certificate
type.
</p></dd></dl>

<a name="gnutls_005fcertificate_005ftype_005fget_005fid-1"></a>
<h4 class="subheading">gnutls_certificate_type_get_id</h4>
<a name="gnutls_005fcertificate_005ftype_005fget_005fid"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005ftype_005fget_005fid"></a>Function: <em>gnutls_certificate_type_t</em> <strong>gnutls_certificate_type_get_id</strong> <em>(const char * <var>name</var>)</em></dt>
<dd><p><var>name</var>: is a certificate type name
</p>
<p>The names are compared in a case insensitive way.
</p>
<p><strong>Returns:</strong> a <code>gnutls_certificate_type_t</code>  for the specified in a
string certificate type, or <code>GNUTLS_CRT_UNKNOWN</code>  on error.
</p></dd></dl>

<a name="gnutls_005fcertificate_005ftype_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_certificate_type_get_name</h4>
<a name="gnutls_005fcertificate_005ftype_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005ftype_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_certificate_type_get_name</strong> <em>(gnutls_certificate_type_t           <var>type</var>)</em></dt>
<dd><p><var>type</var>: is a certificate type
</p>
<p>Convert a <code>gnutls_certificate_type_t</code>  type to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified
certificate type, or <code>NULL</code>  in case of unknown types.
</p></dd></dl>

<a name="gnutls_005fcertificate_005ftype_005flist-1"></a>
<h4 class="subheading">gnutls_certificate_type_list</h4>
<a name="gnutls_005fcertificate_005ftype_005flist"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005ftype_005flist"></a>Function: <em>const gnutls_certificate_type_t *</em> <strong>gnutls_certificate_type_list</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>Get a list of certificate types.
</p>
<p><strong>Returns:</strong> a (0)-terminated list of <code>gnutls_certificate_type_t</code> 
integers indicating the available certificate types.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fverification_005fstatus_005fprint-1"></a>
<h4 class="subheading">gnutls_certificate_verification_status_print</h4>
<a name="gnutls_005fcertificate_005fverification_005fstatus_005fprint"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fverification_005fstatus_005fprint"></a>Function: <em>int</em> <strong>gnutls_certificate_verification_status_print</strong> <em>(unsigned int <var>status</var>, gnutls_certificate_type_t           <var>type</var>, gnutls_datum_t * <var>out</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>status</var>: The status flags to be printed
</p>
<p><var>type</var>: The certificate type
</p>
<p><var>out</var>: Newly allocated datum with (0) terminated string.
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will pretty print the status of a verification
process &ndash; eg. the one obtained by <code>gnutls_certificate_verify_peers3()</code> .
</p>
<p>The output  <code>out</code> needs to be deallocated using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.4
</p></dd></dl>

<a name="gnutls_005fcertificate_005fverify_005fpeers-1"></a>
<h4 class="subheading">gnutls_certificate_verify_peers</h4>
<a name="gnutls_005fcertificate_005fverify_005fpeers"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fverify_005fpeers"></a>Function: <em>int</em> <strong>gnutls_certificate_verify_peers</strong> <em>(gnutls_session_t <var>session</var>, gnutls_typed_vdata_st * <var>data</var>, unsigned int <var>elements</var>, unsigned int * <var>status</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p><var>data</var>: an array of typed data
</p>
<p><var>elements</var>: the number of data elements
</p>
<p><var>status</var>: is the output of the verification
</p>
<p>This function will verify the peer&rsquo;s certificate and store the
status in the  <code>status</code> variable as a bitwise or&rsquo;d gnutls_certificate_status_t
values or zero if the certificate is trusted. Note that value in  <code>status</code> is set only when the return value of this function is success (i.e, failure 
to trust a certificate does not imply a negative return value).
The default verification flags used by this function can be overridden
using <code>gnutls_certificate_set_verify_flags()</code> . See the documentation
of <code>gnutls_certificate_verify_peers2()</code>  for details in the verification process.
</p>
<p>The acceptable  <code>data</code> types are <code>GNUTLS_DT_DNS_HOSTNAME</code> , <code>GNUTLS_DT_RFC822NAME</code>  and <code>GNUTLS_DT_KEY_PURPOSE_OID</code> .
The former two accept as data a null-terminated hostname or email address, and the latter a null-terminated
object identifier (e.g., <code>GNUTLS_KP_TLS_WWW_SERVER</code> ).
If a DNS hostname is provided then this function will compare
the hostname in the certificate against the given. If names do not match the 
<code>GNUTLS_CERT_UNEXPECTED_OWNER</code>  status flag will be set.
If a key purpose OID is provided and the end-certificate contains the extended key
usage PKIX extension, it will be required to be have the provided key purpose 
or be marked for any purpose, otherwise verification will fail with <code>GNUTLS_CERT_SIGNER_CONSTRAINTS_FAILURE</code>  status.
</p>
<p><strong>Returns:</strong> a negative error code on error and <code>GNUTLS_E_SUCCESS</code>  (0)
when the peer&rsquo;s certificate was successfully parsed, whether or not
it was verified.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fverify_005fpeers2-1"></a>
<h4 class="subheading">gnutls_certificate_verify_peers2</h4>
<a name="gnutls_005fcertificate_005fverify_005fpeers2"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fverify_005fpeers2"></a>Function: <em>int</em> <strong>gnutls_certificate_verify_peers2</strong> <em>(gnutls_session_t <var>session</var>, unsigned int * <var>status</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p><var>status</var>: is the output of the verification
</p>
<p>This function will verify the peer&rsquo;s certificate and store
the status in the  <code>status</code> variable as a bitwise or&rsquo;d gnutls_certificate_status_t
values or zero if the certificate is trusted. Note that value in  <code>status</code> is set only when the return value of this function is success (i.e, failure 
to trust a certificate does not imply a negative return value).
The default verification flags used by this function can be overridden
using <code>gnutls_certificate_set_verify_flags()</code> .
</p>
<p>This function will take into account the OCSP Certificate Status TLS extension,
as well as the following X.509 certificate extensions: Name Constraints,
Key Usage, and Basic Constraints (pathlen).
</p>
<p>To avoid denial of service attacks some
default upper limits regarding the certificate key size and chain
size are set. To override them use <code>gnutls_certificate_set_verify_limits()</code> .
</p>
<p>Note that you must also check the peer&rsquo;s name in order to check if
the verified certificate belongs to the actual peer, see <code>gnutls_x509_crt_check_hostname()</code> ,
or use <code>gnutls_certificate_verify_peers3()</code> .
</p>
<p><strong>Returns:</strong> a negative error code on error and <code>GNUTLS_E_SUCCESS</code>  (0)
when the peer&rsquo;s certificate was successfully parsed, whether or not
it was verified.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fverify_005fpeers3-1"></a>
<h4 class="subheading">gnutls_certificate_verify_peers3</h4>
<a name="gnutls_005fcertificate_005fverify_005fpeers3"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fverify_005fpeers3"></a>Function: <em>int</em> <strong>gnutls_certificate_verify_peers3</strong> <em>(gnutls_session_t <var>session</var>, const char * <var>hostname</var>, unsigned int * <var>status</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p><var>hostname</var>: is the expected name of the peer; may be <code>NULL</code> 
</p>
<p><var>status</var>: is the output of the verification
</p>
<p>This function will verify the peer&rsquo;s certificate and store the
status in the  <code>status</code> variable as a bitwise or&rsquo;d gnutls_certificate_status_t
values or zero if the certificate is trusted. Note that value in  <code>status</code> is set only when the return value of this function is success (i.e, failure 
to trust a certificate does not imply a negative return value).
The default verification flags used by this function can be overridden
using <code>gnutls_certificate_set_verify_flags()</code> . See the documentation
of <code>gnutls_certificate_verify_peers2()</code>  for details in the verification process.
</p>
<p>If the  <code>hostname</code> provided is non-NULL then this function will compare
the hostname in the certificate against the given. The comparison will
be accurate for ascii names; non-ascii names are compared byte-by-byte. 
If names do not match the <code>GNUTLS_CERT_UNEXPECTED_OWNER</code>  status flag will be set.
</p>
<p>In order to verify the purpose of the end-certificate (by checking the extended
key usage), use <code>gnutls_certificate_verify_peers()</code> .
</p>
<p><strong>Returns:</strong> a negative error code on error and <code>GNUTLS_E_SUCCESS</code>  (0) 
when the peer&rsquo;s certificate was successfully parsed, whether or not
it was verified.
</p>
<p><strong>Since:</strong> 3.1.4
</p></dd></dl>

<a name="gnutls_005fcheck_005fversion-1"></a>
<h4 class="subheading">gnutls_check_version</h4>
<a name="gnutls_005fcheck_005fversion"></a><dl>
<dt><a name="index-gnutls_005fcheck_005fversion"></a>Function: <em>const char *</em> <strong>gnutls_check_version</strong> <em>(const char * <var>req_version</var>)</em></dt>
<dd><p><var>req_version</var>: version string to compare with, or <code>NULL</code> .
</p>
<p>Check GnuTLS Library version.
</p>
<p>See <code>GNUTLS_VERSION</code>  for a suitable  <code>req_version</code> string.
</p>
<p><strong>Returns:</strong> Check that the version of the library is at
minimum the one given as a string in  <code>req_version</code> and return the
actual version string of the library; return <code>NULL</code>  if the
condition is not met.  If <code>NULL</code>  is passed to this function no
check is done and only the version string is returned.
</p></dd></dl>

<a name="gnutls_005fcipher_005fget-1"></a>
<h4 class="subheading">gnutls_cipher_get</h4>
<a name="gnutls_005fcipher_005fget"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fget"></a>Function: <em>gnutls_cipher_algorithm_t</em> <strong>gnutls_cipher_get</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Get currently used cipher.
</p>
<p><strong>Returns:</strong> the currently used cipher, a <code>gnutls_cipher_algorithm_t</code> 
type.
</p></dd></dl>

<a name="gnutls_005fcipher_005fget_005fid-1"></a>
<h4 class="subheading">gnutls_cipher_get_id</h4>
<a name="gnutls_005fcipher_005fget_005fid"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fget_005fid"></a>Function: <em>gnutls_cipher_algorithm_t</em> <strong>gnutls_cipher_get_id</strong> <em>(const char * <var>name</var>)</em></dt>
<dd><p><var>name</var>: is a cipher algorithm name
</p>
<p>The names are compared in a case insensitive way.
</p>
<p><strong>Returns:</strong> return a <code>gnutls_cipher_algorithm_t</code>  value corresponding to
the specified cipher, or <code>GNUTLS_CIPHER_UNKNOWN</code>  on error.
</p></dd></dl>

<a name="gnutls_005fcipher_005fget_005fkey_005fsize-1"></a>
<h4 class="subheading">gnutls_cipher_get_key_size</h4>
<a name="gnutls_005fcipher_005fget_005fkey_005fsize"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fget_005fkey_005fsize"></a>Function: <em>size_t</em> <strong>gnutls_cipher_get_key_size</strong> <em>(gnutls_cipher_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is an encryption algorithm
</p>
<p>Get key size for cipher.
</p>
<p><strong>Returns:</strong> length (in bytes) of the given cipher&rsquo;s key size, or 0 if
the given cipher is invalid.
</p></dd></dl>

<a name="gnutls_005fcipher_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_cipher_get_name</h4>
<a name="gnutls_005fcipher_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_cipher_get_name</strong> <em>(gnutls_cipher_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is an encryption algorithm
</p>
<p>Convert a <code>gnutls_cipher_algorithm_t</code>  type to a string.
</p>
<p><strong>Returns:</strong> a pointer to a string that contains the name of the
specified cipher, or <code>NULL</code> .
</p></dd></dl>

<a name="gnutls_005fcipher_005flist-1"></a>
<h4 class="subheading">gnutls_cipher_list</h4>
<a name="gnutls_005fcipher_005flist"></a><dl>
<dt><a name="index-gnutls_005fcipher_005flist"></a>Function: <em>const gnutls_cipher_algorithm_t *</em> <strong>gnutls_cipher_list</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>Get a list of supported cipher algorithms.  Note that not
necessarily all ciphers are supported as TLS cipher suites.  For
example, DES is not supported as a cipher suite, but is supported
for other purposes (e.g., PKCS<code>8</code>  or similar).
</p>
<p>This function is not thread safe.
</p>
<p><strong>Returns:</strong> a (0)-terminated list of <code>gnutls_cipher_algorithm_t</code> 
integers indicating the available ciphers.
</p></dd></dl>

<a name="gnutls_005fcipher_005fsuite_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_cipher_suite_get_name</h4>
<a name="gnutls_005fcipher_005fsuite_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fsuite_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_cipher_suite_get_name</strong> <em>(gnutls_kx_algorithm_t       <var>kx_algorithm</var>, gnutls_cipher_algorithm_t       <var>cipher_algorithm</var>, gnutls_mac_algorithm_t       <var>mac_algorithm</var>)</em></dt>
<dd><p><var>kx_algorithm</var>: is a Key exchange algorithm
</p>
<p><var>cipher_algorithm</var>: is a cipher algorithm
</p>
<p><var>mac_algorithm</var>: is a MAC algorithm
</p>
<p>Note that the full cipher suite name must be prepended by TLS or
SSL depending of the protocol in use.
</p>
<p><strong>Returns:</strong> a string that contains the name of a TLS cipher suite,
specified by the given algorithms, or <code>NULL</code> .
</p></dd></dl>

<a name="gnutls_005fcipher_005fsuite_005finfo-1"></a>
<h4 class="subheading">gnutls_cipher_suite_info</h4>
<a name="gnutls_005fcipher_005fsuite_005finfo"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fsuite_005finfo"></a>Function: <em>const char *</em> <strong>gnutls_cipher_suite_info</strong> <em>(size_t <var>idx</var>, unsigned char * <var>cs_id</var>, gnutls_kx_algorithm_t * <var>kx</var>, gnutls_cipher_algorithm_t * <var>cipher</var>, gnutls_mac_algorithm_t * <var>mac</var>, gnutls_protocol_t * <var>min_version</var>)</em></dt>
<dd><p><var>idx</var>: index of cipher suite to get information about, starts on 0.
</p>
<p><var>cs_id</var>: output buffer with room for 2 bytes, indicating cipher suite value
</p>
<p><var>kx</var>: output variable indicating key exchange algorithm, or <code>NULL</code> .
</p>
<p><var>cipher</var>: output variable indicating cipher, or <code>NULL</code> .
</p>
<p><var>mac</var>: output variable indicating MAC algorithm, or <code>NULL</code> .
</p>
<p><var>min_version</var>: output variable indicating TLS protocol version, or <code>NULL</code> .
</p>
<p>Get information about supported cipher suites.  Use the function
iteratively to get information about all supported cipher suites.
Call with idx=0 to get information about first cipher suite, then
idx=1 and so on until the function returns NULL.
</p>
<p><strong>Returns:</strong> the name of  <code>idx</code> cipher suite, and set the information
about the cipher suite in the output variables.  If  <code>idx</code> is out of
bounds, <code>NULL</code>  is returned.
</p></dd></dl>

<a name="gnutls_005fcompression_005fget-1"></a>
<h4 class="subheading">gnutls_compression_get</h4>
<a name="gnutls_005fcompression_005fget"></a><dl>
<dt><a name="index-gnutls_005fcompression_005fget"></a>Function: <em>gnutls_compression_method_t</em> <strong>gnutls_compression_get</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Get currently used compression algorithm.
</p>
<p><strong>Returns:</strong> the currently used compression method, a
<code>gnutls_compression_method_t</code>  value.
</p></dd></dl>

<a name="gnutls_005fcompression_005fget_005fid-1"></a>
<h4 class="subheading">gnutls_compression_get_id</h4>
<a name="gnutls_005fcompression_005fget_005fid"></a><dl>
<dt><a name="index-gnutls_005fcompression_005fget_005fid"></a>Function: <em>gnutls_compression_method_t</em> <strong>gnutls_compression_get_id</strong> <em>(const char * <var>name</var>)</em></dt>
<dd><p><var>name</var>: is a compression method name
</p>
<p>The names are compared in a case insensitive way.
</p>
<p><strong>Returns:</strong> an id of the specified in a string compression method, or
<code>GNUTLS_COMP_UNKNOWN</code>  on error.
</p></dd></dl>

<a name="gnutls_005fcompression_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_compression_get_name</h4>
<a name="gnutls_005fcompression_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fcompression_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_compression_get_name</strong> <em>(gnutls_compression_method_t      <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is a Compression algorithm
</p>
<p>Convert a <code>gnutls_compression_method_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a pointer to a string that contains the name of the
specified compression algorithm, or <code>NULL</code> .
</p></dd></dl>

<a name="gnutls_005fcompression_005flist-1"></a>
<h4 class="subheading">gnutls_compression_list</h4>
<a name="gnutls_005fcompression_005flist"></a><dl>
<dt><a name="index-gnutls_005fcompression_005flist"></a>Function: <em>const gnutls_compression_method_t *</em> <strong>gnutls_compression_list</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>Get a list of compression methods.  
</p>
<p><strong>Returns:</strong> a zero-terminated list of <code>gnutls_compression_method_t</code> 
integers indicating the available compression methods.
</p></dd></dl>

<a name="gnutls_005fcredentials_005fclear-1"></a>
<h4 class="subheading">gnutls_credentials_clear</h4>
<a name="gnutls_005fcredentials_005fclear"></a><dl>
<dt><a name="index-gnutls_005fcredentials_005fclear"></a>Function: <em>void</em> <strong>gnutls_credentials_clear</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Clears all the credentials previously set in this session.
</p></dd></dl>

<a name="gnutls_005fcredentials_005fget-1"></a>
<h4 class="subheading">gnutls_credentials_get</h4>
<a name="gnutls_005fcredentials_005fget"></a><dl>
<dt><a name="index-gnutls_005fcredentials_005fget"></a>Function: <em>int</em> <strong>gnutls_credentials_get</strong> <em>(gnutls_session_t <var>session</var>, gnutls_credentials_type_t <var>type</var>, void ** <var>cred</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>type</var>: is the type of the credentials to return
</p>
<p><var>cred</var>: will contain the credentials.
</p>
<p>Returns the previously provided credentials structures.
</p>
<p>For <code>GNUTLS_CRD_ANON</code> ,  <code>cred</code> will be
<code>gnutls_anon_client_credentials_t</code>  in case of a client.  In case of
a server it should be <code>gnutls_anon_server_credentials_t</code> .
</p>
<p>For <code>GNUTLS_CRD_SRP</code> ,  <code>cred</code> will be <code>gnutls_srp_client_credentials_t</code> 
in case of a client, and <code>gnutls_srp_server_credentials_t</code> , in case
of a server.
</p>
<p>For <code>GNUTLS_CRD_CERTIFICATE</code> ,  <code>cred</code> will be
<code>gnutls_certificate_credentials_t</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p><strong>Since:</strong> 3.3.3
</p></dd></dl>

<a name="gnutls_005fcredentials_005fset-1"></a>
<h4 class="subheading">gnutls_credentials_set</h4>
<a name="gnutls_005fcredentials_005fset"></a><dl>
<dt><a name="index-gnutls_005fcredentials_005fset-1"></a>Function: <em>int</em> <strong>gnutls_credentials_set</strong> <em>(gnutls_session_t <var>session</var>, gnutls_credentials_type_t <var>type</var>, void * <var>cred</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>type</var>: is the type of the credentials
</p>
<p><var>cred</var>: the credentials to set
</p>
<p>Sets the needed credentials for the specified type.  Eg username,
password - or public and private keys etc.  The  <code>cred</code> parameter is
a structure that depends on the specified type and on the current
session (client or server).
</p>
<p>In order to minimize memory usage, and share credentials between
several threads gnutls keeps a pointer to cred, and not the whole
cred structure.  Thus you will have to keep the structure allocated
until you call <code>gnutls_deinit()</code> .
</p>
<p>For <code>GNUTLS_CRD_ANON</code> ,  <code>cred</code> should be
<code>gnutls_anon_client_credentials_t</code>  in case of a client.  In case of
a server it should be <code>gnutls_anon_server_credentials_t</code> .
</p>
<p>For <code>GNUTLS_CRD_SRP</code> ,  <code>cred</code> should be <code>gnutls_srp_client_credentials_t</code> 
in case of a client, and <code>gnutls_srp_server_credentials_t</code> , in case
of a server.
</p>
<p>For <code>GNUTLS_CRD_CERTIFICATE</code> ,  <code>cred</code> should be
<code>gnutls_certificate_credentials_t</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fdb_005fcheck_005fentry-1"></a>
<h4 class="subheading">gnutls_db_check_entry</h4>
<a name="gnutls_005fdb_005fcheck_005fentry"></a><dl>
<dt><a name="index-gnutls_005fdb_005fcheck_005fentry"></a>Function: <em>int</em> <strong>gnutls_db_check_entry</strong> <em>(gnutls_session_t <var>session</var>, gnutls_datum_t <var>session_entry</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>session_entry</var>: is the session data (not key)
</p>
<p>This function has no effect. 
</p>
<p><strong>Returns:</strong> Returns <code>GNUTLS_E_EXPIRED</code> , if the database entry has
expired or 0 otherwise.
</p></dd></dl>

<a name="gnutls_005fdb_005fcheck_005fentry_005ftime-1"></a>
<h4 class="subheading">gnutls_db_check_entry_time</h4>
<a name="gnutls_005fdb_005fcheck_005fentry_005ftime"></a><dl>
<dt><a name="index-gnutls_005fdb_005fcheck_005fentry_005ftime"></a>Function: <em>time_t</em> <strong>gnutls_db_check_entry_time</strong> <em>(gnutls_datum_t * <var>entry</var>)</em></dt>
<dd><p><var>entry</var>: is a pointer to a <code>gnutls_datum_t</code>  type.
</p>
<p>This function returns the time that this entry was active.
It can be used for database entry expiration.
</p>
<p><strong>Returns:</strong> The time this entry was created, or zero on error.
</p></dd></dl>

<a name="gnutls_005fdb_005fget_005fdefault_005fcache_005fexpiration-1"></a>
<h4 class="subheading">gnutls_db_get_default_cache_expiration</h4>
<a name="gnutls_005fdb_005fget_005fdefault_005fcache_005fexpiration"></a><dl>
<dt><a name="index-gnutls_005fdb_005fget_005fdefault_005fcache_005fexpiration"></a>Function: <em>unsigned</em> <strong>gnutls_db_get_default_cache_expiration</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>Returns the expiration time (in seconds) of stored sessions for resumption. 
</p></dd></dl>

<a name="gnutls_005fdb_005fget_005fptr-1"></a>
<h4 class="subheading">gnutls_db_get_ptr</h4>
<a name="gnutls_005fdb_005fget_005fptr"></a><dl>
<dt><a name="index-gnutls_005fdb_005fget_005fptr"></a>Function: <em>void *</em> <strong>gnutls_db_get_ptr</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Get db function pointer.
</p>
<p><strong>Returns:</strong> the pointer that will be sent to db store, retrieve and
delete functions, as the first argument.
</p></dd></dl>

<a name="gnutls_005fdb_005fremove_005fsession-1"></a>
<h4 class="subheading">gnutls_db_remove_session</h4>
<a name="gnutls_005fdb_005fremove_005fsession"></a><dl>
<dt><a name="index-gnutls_005fdb_005fremove_005fsession"></a>Function: <em>void</em> <strong>gnutls_db_remove_session</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function will remove the current session data from the
session database.  This will prevent future handshakes reusing
these session data.  This function should be called if a session
was terminated abnormally, and before <code>gnutls_deinit()</code>  is called.
</p>
<p>Normally <code>gnutls_deinit()</code>  will remove abnormally terminated
sessions.
</p></dd></dl>

<a name="gnutls_005fdb_005fset_005fcache_005fexpiration-1"></a>
<h4 class="subheading">gnutls_db_set_cache_expiration</h4>
<a name="gnutls_005fdb_005fset_005fcache_005fexpiration"></a><dl>
<dt><a name="index-gnutls_005fdb_005fset_005fcache_005fexpiration"></a>Function: <em>void</em> <strong>gnutls_db_set_cache_expiration</strong> <em>(gnutls_session_t <var>session</var>, int <var>seconds</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>seconds</var>: is the number of seconds.
</p>
<p>Set the expiration time for resumed sessions. The default is 3600
(one hour) at the time of this writing.
</p></dd></dl>

<a name="gnutls_005fdb_005fset_005fptr-1"></a>
<h4 class="subheading">gnutls_db_set_ptr</h4>
<a name="gnutls_005fdb_005fset_005fptr"></a><dl>
<dt><a name="index-gnutls_005fdb_005fset_005fptr"></a>Function: <em>void</em> <strong>gnutls_db_set_ptr</strong> <em>(gnutls_session_t <var>session</var>, void * <var>ptr</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>ptr</var>: is the pointer
</p>
<p>Sets the pointer that will be provided to db store, retrieve and
delete functions, as the first argument.
</p></dd></dl>

<a name="gnutls_005fdb_005fset_005fremove_005ffunction-1"></a>
<h4 class="subheading">gnutls_db_set_remove_function</h4>
<a name="gnutls_005fdb_005fset_005fremove_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fdb_005fset_005fremove_005ffunction"></a>Function: <em>void</em> <strong>gnutls_db_set_remove_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_db_remove_func <var>rem_func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>rem_func</var>: is the function.
</p>
<p>Sets the function that will be used to remove data from the
resumed sessions database. This function must return 0 on success.
</p>
<p>The first argument to  <code>rem_func</code> will be null unless
<code>gnutls_db_set_ptr()</code>  has been called.
</p></dd></dl>

<a name="gnutls_005fdb_005fset_005fretrieve_005ffunction-1"></a>
<h4 class="subheading">gnutls_db_set_retrieve_function</h4>
<a name="gnutls_005fdb_005fset_005fretrieve_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fdb_005fset_005fretrieve_005ffunction"></a>Function: <em>void</em> <strong>gnutls_db_set_retrieve_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_db_retr_func <var>retr_func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>retr_func</var>: is the function.
</p>
<p>Sets the function that will be used to retrieve data from the
resumed sessions database.  This function must return a
gnutls_datum_t containing the data on success, or a gnutls_datum_t
containing null and 0 on failure.
</p>
<p>The datum&rsquo;s data must be allocated using the function
<code>gnutls_malloc()</code> .
</p>
<p>The first argument to  <code>retr_func</code> will be null unless
<code>gnutls_db_set_ptr()</code>  has been called.
</p></dd></dl>

<a name="gnutls_005fdb_005fset_005fstore_005ffunction-1"></a>
<h4 class="subheading">gnutls_db_set_store_function</h4>
<a name="gnutls_005fdb_005fset_005fstore_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fdb_005fset_005fstore_005ffunction"></a>Function: <em>void</em> <strong>gnutls_db_set_store_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_db_store_func <var>store_func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>store_func</var>: is the function
</p>
<p>Sets the function that will be used to store data in the resumed
sessions database. This function must return 0 on success.
</p>
<p>The first argument to  <code>store_func</code> will be null unless
<code>gnutls_db_set_ptr()</code>  has been called.
</p></dd></dl>

<a name="gnutls_005fdeinit-1"></a>
<h4 class="subheading">gnutls_deinit</h4>
<a name="gnutls_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fdeinit-1"></a>Function: <em>void</em> <strong>gnutls_deinit</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function clears all buffers associated with the  <code>session</code> .
This function will also remove session data from the session
database if the session was terminated abnormally.
</p></dd></dl>

<a name="gnutls_005fdh_005fget_005fgroup-1"></a>
<h4 class="subheading">gnutls_dh_get_group</h4>
<a name="gnutls_005fdh_005fget_005fgroup"></a><dl>
<dt><a name="index-gnutls_005fdh_005fget_005fgroup"></a>Function: <em>int</em> <strong>gnutls_dh_get_group</strong> <em>(gnutls_session_t <var>session</var>, gnutls_datum_t * <var>raw_gen</var>, gnutls_datum_t * <var>raw_prime</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p><var>raw_gen</var>: will hold the generator.
</p>
<p><var>raw_prime</var>: will hold the prime.
</p>
<p>This function will return the group parameters used in the last
Diffie-Hellman key exchange with the peer.  These are the prime and
the generator used.  This function should be used for both
anonymous and ephemeral Diffie-Hellman.  The output parameters must
be freed with <code>gnutls_free()</code> .
</p>
<p>Note, that the prime and generator are exported as non-negative
integers and may include a leading zero byte.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fdh_005fget_005fpeers_005fpublic_005fbits-1"></a>
<h4 class="subheading">gnutls_dh_get_peers_public_bits</h4>
<a name="gnutls_005fdh_005fget_005fpeers_005fpublic_005fbits"></a><dl>
<dt><a name="index-gnutls_005fdh_005fget_005fpeers_005fpublic_005fbits"></a>Function: <em>int</em> <strong>gnutls_dh_get_peers_public_bits</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p>Get the Diffie-Hellman public key bit size.  Can be used for both
anonymous and ephemeral Diffie-Hellman.
</p>
<p><strong>Returns:</strong> The public key bit size used in the last Diffie-Hellman
key exchange with the peer, or a negative error code in case of error.
</p></dd></dl>

<a name="gnutls_005fdh_005fget_005fprime_005fbits-1"></a>
<h4 class="subheading">gnutls_dh_get_prime_bits</h4>
<a name="gnutls_005fdh_005fget_005fprime_005fbits"></a><dl>
<dt><a name="index-gnutls_005fdh_005fget_005fprime_005fbits"></a>Function: <em>int</em> <strong>gnutls_dh_get_prime_bits</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p>This function will return the bits of the prime used in the last
Diffie-Hellman key exchange with the peer.  Should be used for both
anonymous and ephemeral Diffie-Hellman.  Note that some ciphers,
like RSA and DSA without DHE, do not use a Diffie-Hellman key
exchange, and then this function will return 0.
</p>
<p><strong>Returns:</strong> The Diffie-Hellman bit strength is returned, or 0 if no
Diffie-Hellman key exchange was done, or a negative error code on
failure.
</p></dd></dl>

<a name="gnutls_005fdh_005fget_005fpubkey-1"></a>
<h4 class="subheading">gnutls_dh_get_pubkey</h4>
<a name="gnutls_005fdh_005fget_005fpubkey"></a><dl>
<dt><a name="index-gnutls_005fdh_005fget_005fpubkey"></a>Function: <em>int</em> <strong>gnutls_dh_get_pubkey</strong> <em>(gnutls_session_t <var>session</var>, gnutls_datum_t * <var>raw_key</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p><var>raw_key</var>: will hold the public key.
</p>
<p>This function will return the peer&rsquo;s public key used in the last
Diffie-Hellman key exchange.  This function should be used for both
anonymous and ephemeral Diffie-Hellman.  The output parameters must
be freed with <code>gnutls_free()</code> .
</p>
<p>Note, that public key is exported as non-negative
integer and may include a leading zero byte.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fdh_005fget_005fsecret_005fbits-1"></a>
<h4 class="subheading">gnutls_dh_get_secret_bits</h4>
<a name="gnutls_005fdh_005fget_005fsecret_005fbits"></a><dl>
<dt><a name="index-gnutls_005fdh_005fget_005fsecret_005fbits"></a>Function: <em>int</em> <strong>gnutls_dh_get_secret_bits</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p>This function will return the bits used in the last Diffie-Hellman
key exchange with the peer.  Should be used for both anonymous and
ephemeral Diffie-Hellman.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fdh_005fparams_005fcpy-1"></a>
<h4 class="subheading">gnutls_dh_params_cpy</h4>
<a name="gnutls_005fdh_005fparams_005fcpy"></a><dl>
<dt><a name="index-gnutls_005fdh_005fparams_005fcpy"></a>Function: <em>int</em> <strong>gnutls_dh_params_cpy</strong> <em>(gnutls_dh_params_t <var>dst</var>, gnutls_dh_params_t <var>src</var>)</em></dt>
<dd><p><var>dst</var>: Is the destination parameters, which should be initialized.
</p>
<p><var>src</var>: Is the source parameters
</p>
<p>This function will copy the DH parameters structure from source
to destination.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fdh_005fparams_005fdeinit-1"></a>
<h4 class="subheading">gnutls_dh_params_deinit</h4>
<a name="gnutls_005fdh_005fparams_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fdh_005fparams_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_dh_params_deinit</strong> <em>(gnutls_dh_params_t <var>dh_params</var>)</em></dt>
<dd><p><var>dh_params</var>: The parameters
</p>
<p>This function will deinitialize the DH parameters type.
</p></dd></dl>

<a name="gnutls_005fdh_005fparams_005fexport2_005fpkcs3-1"></a>
<h4 class="subheading">gnutls_dh_params_export2_pkcs3</h4>
<a name="gnutls_005fdh_005fparams_005fexport2_005fpkcs3"></a><dl>
<dt><a name="index-gnutls_005fdh_005fparams_005fexport2_005fpkcs3"></a>Function: <em>int</em> <strong>gnutls_dh_params_export2_pkcs3</strong> <em>(gnutls_dh_params_t <var>params</var>, gnutls_x509_crt_fmt_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>params</var>: Holds the DH parameters
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>out</var>: will contain a PKCS3 DHParams structure PEM or DER encoded
</p>
<p>This function will export the given dh parameters to a PKCS3
DHParams structure. This is the format generated by &quot;openssl dhparam&quot; tool.
The data in  <code>out</code> will be allocated using <code>gnutls_malloc()</code> .
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN DH PARAMETERS&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fdh_005fparams_005fexport_005fpkcs3-1"></a>
<h4 class="subheading">gnutls_dh_params_export_pkcs3</h4>
<a name="gnutls_005fdh_005fparams_005fexport_005fpkcs3"></a><dl>
<dt><a name="index-gnutls_005fdh_005fparams_005fexport_005fpkcs3"></a>Function: <em>int</em> <strong>gnutls_dh_params_export_pkcs3</strong> <em>(gnutls_dh_params_t <var>params</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned char * <var>params_data</var>, size_t * <var>params_data_size</var>)</em></dt>
<dd><p><var>params</var>: Holds the DH parameters
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>params_data</var>: will contain a PKCS3 DHParams structure PEM or DER encoded
</p>
<p><var>params_data_size</var>: holds the size of params_data (and will be replaced by the actual size of parameters)
</p>
<p>This function will export the given dh parameters to a PKCS3
DHParams structure. This is the format generated by &quot;openssl dhparam&quot; tool.
If the buffer provided is not long enough to hold the output, then
GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN DH PARAMETERS&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fdh_005fparams_005fexport_005fraw-1"></a>
<h4 class="subheading">gnutls_dh_params_export_raw</h4>
<a name="gnutls_005fdh_005fparams_005fexport_005fraw"></a><dl>
<dt><a name="index-gnutls_005fdh_005fparams_005fexport_005fraw"></a>Function: <em>int</em> <strong>gnutls_dh_params_export_raw</strong> <em>(gnutls_dh_params_t <var>params</var>, gnutls_datum_t * <var>prime</var>, gnutls_datum_t * <var>generator</var>, unsigned int * <var>bits</var>)</em></dt>
<dd><p><var>params</var>: Holds the DH parameters
</p>
<p><var>prime</var>: will hold the new prime
</p>
<p><var>generator</var>: will hold the new generator
</p>
<p><var>bits</var>: if non null will hold the secret key&rsquo;s number of bits
</p>
<p>This function will export the pair of prime and generator for use
in the Diffie-Hellman key exchange.  The new parameters will be
allocated using <code>gnutls_malloc()</code>  and will be stored in the
appropriate datum.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fdh_005fparams_005fgenerate2-1"></a>
<h4 class="subheading">gnutls_dh_params_generate2</h4>
<a name="gnutls_005fdh_005fparams_005fgenerate2"></a><dl>
<dt><a name="index-gnutls_005fdh_005fparams_005fgenerate2"></a>Function: <em>int</em> <strong>gnutls_dh_params_generate2</strong> <em>(gnutls_dh_params_t <var>dparams</var>, unsigned int <var>bits</var>)</em></dt>
<dd><p><var>dparams</var>: The parameters
</p>
<p><var>bits</var>: is the prime&rsquo;s number of bits
</p>
<p>This function will generate a new pair of prime and generator for use in
the Diffie-Hellman key exchange. The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
This function is normally slow.
</p>
<p>Do not set the number of bits directly, use <code>gnutls_sec_param_to_pk_bits()</code>  to
get bits for <code>GNUTLS_PK_DSA</code> .
Also note that the DH parameters are only useful to servers.
Since clients use the parameters sent by the server, it&rsquo;s of
no use to call this in client side.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fdh_005fparams_005fimport_005fpkcs3-1"></a>
<h4 class="subheading">gnutls_dh_params_import_pkcs3</h4>
<a name="gnutls_005fdh_005fparams_005fimport_005fpkcs3"></a><dl>
<dt><a name="index-gnutls_005fdh_005fparams_005fimport_005fpkcs3"></a>Function: <em>int</em> <strong>gnutls_dh_params_import_pkcs3</strong> <em>(gnutls_dh_params_t <var>params</var>, const gnutls_datum_t * <var>pkcs3_params</var>, gnutls_x509_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>params</var>: The parameters
</p>
<p><var>pkcs3_params</var>: should contain a PKCS3 DHParams structure PEM or DER encoded
</p>
<p><var>format</var>: the format of params. PEM or DER.
</p>
<p>This function will extract the DHParams found in a PKCS3 formatted
structure. This is the format generated by &quot;openssl dhparam&quot; tool.
</p>
<p>If the structure is PEM encoded, it should have a header
of &quot;BEGIN DH PARAMETERS&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fdh_005fparams_005fimport_005fraw-1"></a>
<h4 class="subheading">gnutls_dh_params_import_raw</h4>
<a name="gnutls_005fdh_005fparams_005fimport_005fraw"></a><dl>
<dt><a name="index-gnutls_005fdh_005fparams_005fimport_005fraw"></a>Function: <em>int</em> <strong>gnutls_dh_params_import_raw</strong> <em>(gnutls_dh_params_t <var>dh_params</var>, const gnutls_datum_t * <var>prime</var>, const gnutls_datum_t * <var>generator</var>)</em></dt>
<dd><p><var>dh_params</var>: The parameters
</p>
<p><var>prime</var>: holds the new prime
</p>
<p><var>generator</var>: holds the new generator
</p>
<p>This function will replace the pair of prime and generator for use
in the Diffie-Hellman key exchange.  The new parameters should be
stored in the appropriate gnutls_datum.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fdh_005fparams_005fimport_005fraw2-1"></a>
<h4 class="subheading">gnutls_dh_params_import_raw2</h4>
<a name="gnutls_005fdh_005fparams_005fimport_005fraw2"></a><dl>
<dt><a name="index-gnutls_005fdh_005fparams_005fimport_005fraw2"></a>Function: <em>int</em> <strong>gnutls_dh_params_import_raw2</strong> <em>(gnutls_dh_params_t <var>dh_params</var>, const gnutls_datum_t * <var>prime</var>, const gnutls_datum_t * <var>generator</var>, unsigned <var>key_bits</var>)</em></dt>
<dd><p><var>dh_params</var>: The parameters
</p>
<p><var>prime</var>: holds the new prime
</p>
<p><var>generator</var>: holds the new generator
</p>
<p><var>key_bits</var>: the private key bits (set to zero when unknown)
</p>
<p>This function will replace the pair of prime and generator for use
in the Diffie-Hellman key exchange.  The new parameters should be
stored in the appropriate gnutls_datum.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fdh_005fparams_005finit-1"></a>
<h4 class="subheading">gnutls_dh_params_init</h4>
<a name="gnutls_005fdh_005fparams_005finit"></a><dl>
<dt><a name="index-gnutls_005fdh_005fparams_005finit"></a>Function: <em>int</em> <strong>gnutls_dh_params_init</strong> <em>(gnutls_dh_params_t * <var>dh_params</var>)</em></dt>
<dd><p><var>dh_params</var>: The parameters
</p>
<p>This function will initialize the DH parameters type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fdh_005fset_005fprime_005fbits-1"></a>
<h4 class="subheading">gnutls_dh_set_prime_bits</h4>
<a name="gnutls_005fdh_005fset_005fprime_005fbits"></a><dl>
<dt><a name="index-gnutls_005fdh_005fset_005fprime_005fbits"></a>Function: <em>void</em> <strong>gnutls_dh_set_prime_bits</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>bits</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>bits</var>: is the number of bits
</p>
<p>This function sets the number of bits, for use in a Diffie-Hellman
key exchange.  This is used both in DH ephemeral and DH anonymous
cipher suites.  This will set the minimum size of the prime that
will be used for the handshake.
</p>
<p>In the client side it sets the minimum accepted number of bits.  If
a server sends a prime with less bits than that
<code>GNUTLS_E_DH_PRIME_UNACCEPTABLE</code>  will be returned by the handshake.
</p>
<p>Note that this function will warn via the audit log for value that
are believed to be weak.
</p>
<p>The function has no effect in server side.
</p>
<p>Note that since 3.1.7 this function is deprecated. The minimum
number of bits is set by the priority string level.
Also this function must be called after <code>gnutls_priority_set_direct()</code> 
or the set value may be overridden by the selected priority options.
</p></dd></dl>

<a name="gnutls_005fdigest_005fget_005fid-1"></a>
<h4 class="subheading">gnutls_digest_get_id</h4>
<a name="gnutls_005fdigest_005fget_005fid"></a><dl>
<dt><a name="index-gnutls_005fdigest_005fget_005fid"></a>Function: <em>gnutls_digest_algorithm_t</em> <strong>gnutls_digest_get_id</strong> <em>(const char * <var>name</var>)</em></dt>
<dd><p><var>name</var>: is a digest algorithm name
</p>
<p>Convert a string to a <code>gnutls_digest_algorithm_t</code>  value.  The names are
compared in a case insensitive way.
</p>
<p><strong>Returns:</strong> a <code>gnutls_digest_algorithm_t</code>  id of the specified MAC
algorithm string, or <code>GNUTLS_DIG_UNKNOWN</code>  on failure.
</p></dd></dl>

<a name="gnutls_005fdigest_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_digest_get_name</h4>
<a name="gnutls_005fdigest_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fdigest_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_digest_get_name</strong> <em>(gnutls_digest_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is a digest algorithm
</p>
<p>Convert a <code>gnutls_digest_algorithm_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified digest
algorithm, or <code>NULL</code> .
</p></dd></dl>

<a name="gnutls_005fdigest_005fget_005foid-1"></a>
<h4 class="subheading">gnutls_digest_get_oid</h4>
<a name="gnutls_005fdigest_005fget_005foid"></a><dl>
<dt><a name="index-gnutls_005fdigest_005fget_005foid"></a>Function: <em>const char *</em> <strong>gnutls_digest_get_oid</strong> <em>(gnutls_digest_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is a digest algorithm
</p>
<p>Convert a <code>gnutls_digest_algorithm_t</code>  value to its object identifier.
</p>
<p><strong>Returns:</strong> a string that contains the object identifier of the specified digest
algorithm, or <code>NULL</code> .
</p>
<p><strong>Since:</strong> 3.4.3
</p></dd></dl>

<a name="gnutls_005fdigest_005flist-1"></a>
<h4 class="subheading">gnutls_digest_list</h4>
<a name="gnutls_005fdigest_005flist"></a><dl>
<dt><a name="index-gnutls_005fdigest_005flist"></a>Function: <em>const gnutls_digest_algorithm_t *</em> <strong>gnutls_digest_list</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>Get a list of hash (digest) algorithms supported by GnuTLS.
</p>
<p>This function is not thread safe.
</p>
<p><strong>Returns:</strong> Return a (0)-terminated list of <code>gnutls_digest_algorithm_t</code> 
integers indicating the available digests.
</p></dd></dl>

<a name="gnutls_005fecc_005fcurve_005fget-1"></a>
<h4 class="subheading">gnutls_ecc_curve_get</h4>
<a name="gnutls_005fecc_005fcurve_005fget"></a><dl>
<dt><a name="index-gnutls_005fecc_005fcurve_005fget"></a>Function: <em>gnutls_ecc_curve_t</em> <strong>gnutls_ecc_curve_get</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Returns the currently used elliptic curve. Only valid
when using an elliptic curve ciphersuite.
</p>
<p><strong>Returns:</strong> the currently used curve, a <code>gnutls_ecc_curve_t</code> 
type.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fecc_005fcurve_005fget_005fid-1"></a>
<h4 class="subheading">gnutls_ecc_curve_get_id</h4>
<a name="gnutls_005fecc_005fcurve_005fget_005fid"></a><dl>
<dt><a name="index-gnutls_005fecc_005fcurve_005fget_005fid"></a>Function: <em>gnutls_ecc_curve_t</em> <strong>gnutls_ecc_curve_get_id</strong> <em>(const char * <var>name</var>)</em></dt>
<dd><p><var>name</var>: is a curve name
</p>
<p>The names are compared in a case insensitive way.
</p>
<p><strong>Returns:</strong> return a <code>gnutls_ecc_curve_t</code>  value corresponding to
the specified curve, or <code>GNUTLS_ECC_CURVE_INVALID</code>  on error.
</p>
<p><strong>Since:</strong> 3.4.3
</p></dd></dl>

<a name="gnutls_005fecc_005fcurve_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_ecc_curve_get_name</h4>
<a name="gnutls_005fecc_005fcurve_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fecc_005fcurve_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_ecc_curve_get_name</strong> <em>(gnutls_ecc_curve_t <var>curve</var>)</em></dt>
<dd><p><var>curve</var>: is an ECC curve
</p>
<p>Convert a <code>gnutls_ecc_curve_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified
curve or <code>NULL</code> .
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fecc_005fcurve_005fget_005foid-1"></a>
<h4 class="subheading">gnutls_ecc_curve_get_oid</h4>
<a name="gnutls_005fecc_005fcurve_005fget_005foid"></a><dl>
<dt><a name="index-gnutls_005fecc_005fcurve_005fget_005foid"></a>Function: <em>const char *</em> <strong>gnutls_ecc_curve_get_oid</strong> <em>(gnutls_ecc_curve_t <var>curve</var>)</em></dt>
<dd><p><var>curve</var>: is an ECC curve
</p>
<p>Convert a <code>gnutls_ecc_curve_t</code>  value to its object identifier.
</p>
<p><strong>Returns:</strong> a string that contains the OID of the specified
curve or <code>NULL</code> .
</p>
<p><strong>Since:</strong> 3.4.3
</p></dd></dl>

<a name="gnutls_005fecc_005fcurve_005fget_005fsize-1"></a>
<h4 class="subheading">gnutls_ecc_curve_get_size</h4>
<a name="gnutls_005fecc_005fcurve_005fget_005fsize"></a><dl>
<dt><a name="index-gnutls_005fecc_005fcurve_005fget_005fsize"></a>Function: <em>int</em> <strong>gnutls_ecc_curve_get_size</strong> <em>(gnutls_ecc_curve_t <var>curve</var>)</em></dt>
<dd><p><var>curve</var>: is an ECC curve
</p>
<p>Returns the size in bytes of the curve.
</p>
<p><strong>Returns:</strong> a the size or (0).
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fecc_005fcurve_005flist-1"></a>
<h4 class="subheading">gnutls_ecc_curve_list</h4>
<a name="gnutls_005fecc_005fcurve_005flist"></a><dl>
<dt><a name="index-gnutls_005fecc_005fcurve_005flist"></a>Function: <em>const gnutls_ecc_curve_t *</em> <strong>gnutls_ecc_curve_list</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>Get the list of supported elliptic curves.
</p>
<p>This function is not thread safe.
</p>
<p><strong>Returns:</strong> Return a (0)-terminated list of <code>gnutls_ecc_curve_t</code> 
integers indicating the available curves.
</p></dd></dl>

<a name="gnutls_005ferror_005fis_005ffatal-1"></a>
<h4 class="subheading">gnutls_error_is_fatal</h4>
<a name="gnutls_005ferror_005fis_005ffatal"></a><dl>
<dt><a name="index-gnutls_005ferror_005fis_005ffatal-1"></a>Function: <em>int</em> <strong>gnutls_error_is_fatal</strong> <em>(int <var>error</var>)</em></dt>
<dd><p><var>error</var>: is a GnuTLS error code, a negative error code
</p>
<p>If a GnuTLS function returns a negative error code you may feed that
value to this function to see if the error condition is fatal to
a TLS session (i.e., must be terminated). 
</p>
<p>Note that you may also want to check the error code manually, since some
non-fatal errors to the protocol (such as a warning alert or
a rehandshake request) may be fatal for your program.
</p>
<p>This function is only useful if you are dealing with errors from
functions that relate to a TLS session (e.g., record layer or handshake 
layer handling functions).
</p>
<p><strong>Returns:</strong> Non-zero value on fatal errors or zero on non-fatal.
</p></dd></dl>

<a name="gnutls_005ferror_005fto_005falert-1"></a>
<h4 class="subheading">gnutls_error_to_alert</h4>
<a name="gnutls_005ferror_005fto_005falert"></a><dl>
<dt><a name="index-gnutls_005ferror_005fto_005falert-1"></a>Function: <em>int</em> <strong>gnutls_error_to_alert</strong> <em>(int <var>err</var>, int * <var>level</var>)</em></dt>
<dd><p><var>err</var>: is a negative integer
</p>
<p><var>level</var>: the alert level will be stored there
</p>
<p>Get an alert depending on the error code returned by a gnutls
function.  All alerts sent by this function should be considered
fatal.  The only exception is when  <code>err</code> is <code>GNUTLS_E_REHANDSHAKE</code> ,
where a warning alert should be sent to the peer indicating that no
renegotiation will be performed.
</p>
<p>If there is no mapping to a valid alert the alert to indicate
internal error is returned.
</p>
<p><strong>Returns:</strong> the alert code to use for a particular error code.
</p></dd></dl>

<a name="gnutls_005fest_005frecord_005foverhead_005fsize-1"></a>
<h4 class="subheading">gnutls_est_record_overhead_size</h4>
<a name="gnutls_005fest_005frecord_005foverhead_005fsize"></a><dl>
<dt><a name="index-gnutls_005fest_005frecord_005foverhead_005fsize"></a>Function: <em>size_t</em> <strong>gnutls_est_record_overhead_size</strong> <em>(gnutls_protocol_t <var>version</var>, gnutls_cipher_algorithm_t <var>cipher</var>, gnutls_mac_algorithm_t <var>mac</var>, gnutls_compression_method_t <var>comp</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>version</var>: is a <code>gnutls_protocol_t</code>  value
</p>
<p><var>cipher</var>: is a <code>gnutls_cipher_algorithm_t</code>  value
</p>
<p><var>mac</var>: is a <code>gnutls_mac_algorithm_t</code>  value
</p>
<p><var>comp</var>: is a <code>gnutls_compression_method_t</code>  value
</p>
<p><var>flags</var>: must be zero
</p>
<p>This function will return the set size in bytes of the overhead
due to TLS (or DTLS) per record.
</p>
<p>Note that this function may provide inacurate values when TLS
extensions that modify the record format are negotiated. In these
cases a more accurate value can be obtained using <code>gnutls_record_overhead_size()</code>  
after a completed handshake.
</p>
<p><strong>Since:</strong> 3.2.2
</p></dd></dl>

<a name="gnutls_005fext_005fget_005fdata-1"></a>
<h4 class="subheading">gnutls_ext_get_data</h4>
<a name="gnutls_005fext_005fget_005fdata"></a><dl>
<dt><a name="index-gnutls_005fext_005fget_005fdata"></a>Function: <em>int</em> <strong>gnutls_ext_get_data</strong> <em>(gnutls_session_t <var>session</var>, unsigned <var>type</var>, gnutls_ext_priv_data_t * <var>data</var>)</em></dt>
<dd><p><var>session</var>: a <code>gnutls_session_t</code>  opaque pointer
</p>
<p><var>type</var>: the numeric id of the extension
</p>
<p><var>data</var>: a pointer to the private data to retrieve
</p>
<p>This function retrieves any data previously stored with <code>gnutls_ext_set_data()</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fext_005fregister-1"></a>
<h4 class="subheading">gnutls_ext_register</h4>
<a name="gnutls_005fext_005fregister"></a><dl>
<dt><a name="index-gnutls_005fext_005fregister"></a>Function: <em>int</em> <strong>gnutls_ext_register</strong> <em>(const char * <var>name</var>, int <var>type</var>, gnutls_ext_parse_type_t <var>parse_type</var>, gnutls_ext_recv_func <var>recv_func</var>, gnutls_ext_send_func <var>send_func</var>, gnutls_ext_deinit_data_func <var>deinit_func</var>, gnutls_ext_pack_func <var>pack_func</var>, gnutls_ext_unpack_func <var>unpack_func</var>)</em></dt>
<dd><p><var>name</var>: the name of the extension to register
</p>
<p><var>type</var>: the numeric id of the extension
</p>
<p><var>parse_type</var>: the parse type of the extension (see gnutls_ext_parse_type_t)
</p>
<p><var>recv_func</var>: a function to receive the data
</p>
<p><var>send_func</var>: a function to send the data
</p>
<p><var>deinit_func</var>: a function deinitialize any private data
</p>
<p><var>pack_func</var>: a function which serializes the extension&rsquo;s private data (used on session packing for resumption)
</p>
<p><var>unpack_func</var>: a function which will deserialize the extension&rsquo;s private data
</p>
<p>This function will register a new extension type. The extension will remain
registered until <code>gnutls_global_deinit()</code>  is called. If the extension type
is already registred then <code>GNUTLS_E_ALREADY_REGISTERED</code>  will be returned.
</p>
<p>Each registered extension can store temporary data into the gnutls_session_t
structure using <code>gnutls_ext_set_data()</code> , and they can be retrieved using
<code>gnutls_ext_get_data()</code> .
</p>
<p>This function is not thread safe.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fext_005fset_005fdata-1"></a>
<h4 class="subheading">gnutls_ext_set_data</h4>
<a name="gnutls_005fext_005fset_005fdata"></a><dl>
<dt><a name="index-gnutls_005fext_005fset_005fdata"></a>Function: <em>void</em> <strong>gnutls_ext_set_data</strong> <em>(gnutls_session_t <var>session</var>, unsigned <var>type</var>, gnutls_ext_priv_data_t <var>data</var>)</em></dt>
<dd><p><var>session</var>: a <code>gnutls_session_t</code>  opaque pointer
</p>
<p><var>type</var>: the numeric id of the extension
</p>
<p><var>data</var>: the private data to set
</p>
<p>This function allows an extension handler to store data in the current session
and retrieve them later on. The set data will be deallocated using
the gnutls_ext_deinit_data_func.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005ffingerprint-1"></a>
<h4 class="subheading">gnutls_fingerprint</h4>
<a name="gnutls_005ffingerprint"></a><dl>
<dt><a name="index-gnutls_005ffingerprint"></a>Function: <em>int</em> <strong>gnutls_fingerprint</strong> <em>(gnutls_digest_algorithm_t <var>algo</var>, const gnutls_datum_t * <var>data</var>, void * <var>result</var>, size_t * <var>result_size</var>)</em></dt>
<dd><p><var>algo</var>: is a digest algorithm
</p>
<p><var>data</var>: is the data
</p>
<p><var>result</var>: is the place where the result will be copied (may be null).
</p>
<p><var>result_size</var>: should hold the size of the result. The actual size
of the returned result will also be copied there.
</p>
<p>This function will calculate a fingerprint (actually a hash), of
the given data.  The result is not printable data.  You should
convert it to hex, or to something else printable.
</p>
<p>This is the usual way to calculate a fingerprint of an X.509 DER
encoded certificate.  Note however that the fingerprint of an
OpenPGP certificate is not just a hash and cannot be calculated with this
function.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005ffips140_005fmode_005fenabled-1"></a>
<h4 class="subheading">gnutls_fips140_mode_enabled</h4>
<a name="gnutls_005ffips140_005fmode_005fenabled"></a><dl>
<dt><a name="index-gnutls_005ffips140_005fmode_005fenabled"></a>Function: <em>int</em> <strong>gnutls_fips140_mode_enabled</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>Checks whether this library is in FIPS140 mode.
</p>
<p><strong>Returns:</strong> return non-zero if true or zero if false.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fglobal_005fdeinit-1"></a>
<h4 class="subheading">gnutls_global_deinit</h4>
<a name="gnutls_005fglobal_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fglobal_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_global_deinit</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>This function deinitializes the global data, that were initialized
using <code>gnutls_global_init()</code> .
</p></dd></dl>

<a name="gnutls_005fglobal_005finit-1"></a>
<h4 class="subheading">gnutls_global_init</h4>
<a name="gnutls_005fglobal_005finit"></a><dl>
<dt><a name="index-gnutls_005fglobal_005finit"></a>Function: <em>int</em> <strong>gnutls_global_init</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>This function performs any required precalculations, detects
the supported CPU capabilities and initializes the underlying
cryptographic backend. In order to free any resources 
taken by this call you should <code>gnutls_global_deinit()</code>  
when gnutls usage is no longer needed.
</p>
<p>This function increments a global counter, so that
<code>gnutls_global_deinit()</code>  only releases resources when it has been
called as many times as <code>gnutls_global_init()</code> .  This is useful when
GnuTLS is used by more than one library in an application.  This
function can be called many times, but will only do something the
first time.
</p>
<p>Since GnuTLS 3.3.0 this function is automatically called on library
constructor. Since the same version this function is also thread safe.
The automatic initialization can be avoided if the environment variable
<code>GNUTLS_NO_EXPLICIT_INIT</code>  is set to be 1.
</p>
<p>A subsequent call of this function if the initial has failed will
return the same error code.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fglobal_005fset_005faudit_005flog_005ffunction-1"></a>
<h4 class="subheading">gnutls_global_set_audit_log_function</h4>
<a name="gnutls_005fglobal_005fset_005faudit_005flog_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fglobal_005fset_005faudit_005flog_005ffunction-1"></a>Function: <em>void</em> <strong>gnutls_global_set_audit_log_function</strong> <em>(gnutls_audit_log_func <var>log_func</var>)</em></dt>
<dd><p><var>log_func</var>: it is the audit log function
</p>
<p>This is the function to set the audit logging function. This
is a function to report important issues, such as possible
attacks in the protocol. This is different from <code>gnutls_global_set_log_function()</code> 
because it will report also session-specific events. The session
parameter will be null if there is no corresponding TLS session.
</p>
<p><code>gnutls_audit_log_func</code> is of the form,
void (*gnutls_audit_log_func)( gnutls_session_t, const char*);
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fglobal_005fset_005flog_005ffunction-1"></a>
<h4 class="subheading">gnutls_global_set_log_function</h4>
<a name="gnutls_005fglobal_005fset_005flog_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fglobal_005fset_005flog_005ffunction"></a>Function: <em>void</em> <strong>gnutls_global_set_log_function</strong> <em>(gnutls_log_func <var>log_func</var>)</em></dt>
<dd><p><var>log_func</var>: it&rsquo;s a log function
</p>
<p>This is the function where you set the logging function gnutls is
going to use.  This function only accepts a character array.
Normally you may not use this function since it is only used for
debugging purposes.
</p>
<p><code>gnutls_log_func</code> is of the form,
void (*gnutls_log_func)( int level, const char*);
</p></dd></dl>

<a name="gnutls_005fglobal_005fset_005flog_005flevel-1"></a>
<h4 class="subheading">gnutls_global_set_log_level</h4>
<a name="gnutls_005fglobal_005fset_005flog_005flevel"></a><dl>
<dt><a name="index-gnutls_005fglobal_005fset_005flog_005flevel"></a>Function: <em>void</em> <strong>gnutls_global_set_log_level</strong> <em>(int <var>level</var>)</em></dt>
<dd><p><var>level</var>: it&rsquo;s an integer from 0 to 99.
</p>
<p>This is the function that allows you to set the log level.  The
level is an integer between 0 and 9.  Higher values mean more
verbosity. The default value is 0.  Larger values should only be
used with care, since they may reveal sensitive information.
</p>
<p>Use a log level over 10 to enable all debugging options.
</p></dd></dl>

<a name="gnutls_005fglobal_005fset_005fmutex-1"></a>
<h4 class="subheading">gnutls_global_set_mutex</h4>
<a name="gnutls_005fglobal_005fset_005fmutex"></a><dl>
<dt><a name="index-gnutls_005fglobal_005fset_005fmutex-1"></a>Function: <em>void</em> <strong>gnutls_global_set_mutex</strong> <em>(mutex_init_func <var>init</var>, mutex_deinit_func <var>deinit</var>, mutex_lock_func <var>lock</var>, mutex_unlock_func <var>unlock</var>)</em></dt>
<dd><p><var>init</var>: mutex initialization function
</p>
<p><var>deinit</var>: mutex deinitialization function
</p>
<p><var>lock</var>: mutex locking function
</p>
<p><var>unlock</var>: mutex unlocking function
</p>
<p>With this function you are allowed to override the default mutex
locks used in some parts of gnutls and dependent libraries. This function
should be used if you have complete control of your program and libraries.
Do not call this function from a library, or preferably from any application
unless really needed to. GnuTLS will use the appropriate locks for the running
system.
</p>
<p>This function must be called prior to any other gnutls function.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fglobal_005fset_005ftime_005ffunction-1"></a>
<h4 class="subheading">gnutls_global_set_time_function</h4>
<a name="gnutls_005fglobal_005fset_005ftime_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fglobal_005fset_005ftime_005ffunction"></a>Function: <em>void</em> <strong>gnutls_global_set_time_function</strong> <em>(gnutls_time_func <var>time_func</var>)</em></dt>
<dd><p><var>time_func</var>: it&rsquo;s the system time function, a <code>gnutls_time_func()</code>  callback.
</p>
<p>This is the function where you can override the default system time
function.  The application provided function should behave the same
as the standard function.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fhandshake-1"></a>
<h4 class="subheading">gnutls_handshake</h4>
<a name="gnutls_005fhandshake"></a><dl>
<dt><a name="index-gnutls_005fhandshake-1"></a>Function: <em>int</em> <strong>gnutls_handshake</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function does the handshake of the TLS/SSL protocol, and
initializes the TLS connection.
</p>
<p>This function will fail if any problem is encountered, and will
return a negative error code. In case of a client, if the client
has asked to resume a session, but the server couldn&rsquo;t, then a
full handshake will be performed.
</p>
<p>The non-fatal errors expected by this function are:
<code>GNUTLS_E_INTERRUPTED</code> , <code>GNUTLS_E_AGAIN</code> , 
<code>GNUTLS_E_WARNING_ALERT_RECEIVED</code> , and <code>GNUTLS_E_GOT_APPLICATION_DATA</code> ,
the latter only in a case of rehandshake.
</p>
<p>The former two interrupt the handshake procedure due to the lower
layer being interrupted, and the latter because of an alert that
may be sent by a server (it is always a good idea to check any
received alerts). On these errors call this function again, until it
returns 0; cf.  <code>gnutls_record_get_direction()</code>  and
<code>gnutls_error_is_fatal()</code> . In DTLS sessions the non-fatal error
<code>GNUTLS_E_LARGE_PACKET</code>  is also possible, and indicates that
the MTU should be adjusted.
</p>
<p>If this function is called by a server after a rehandshake request
then <code>GNUTLS_E_GOT_APPLICATION_DATA</code>  or
<code>GNUTLS_E_WARNING_ALERT_RECEIVED</code>  may be returned.  Note that these
are non fatal errors, only in the specific case of a rehandshake.
Their meaning is that the client rejected the rehandshake request or
in the case of <code>GNUTLS_E_GOT_APPLICATION_DATA</code>  it could also mean that
some data were pending. A client may receive that error code if
it initiates the handshake and the server doesn&rsquo;t agreed.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p></dd></dl>

<a name="gnutls_005fhandshake_005fdescription_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_handshake_description_get_name</h4>
<a name="gnutls_005fhandshake_005fdescription_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fhandshake_005fdescription_005fget_005fname"></a>Function: <em>const char     *</em> <strong>gnutls_handshake_description_get_name</strong> <em>(gnutls_handshake_description_t         <var>type</var>)</em></dt>
<dd><p><var>type</var>: is a handshake message description
</p>
<p>Convert a <code>gnutls_handshake_description_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified handshake
message or <code>NULL</code> .
</p></dd></dl>

<a name="gnutls_005fhandshake_005fget_005flast_005fin-1"></a>
<h4 class="subheading">gnutls_handshake_get_last_in</h4>
<a name="gnutls_005fhandshake_005fget_005flast_005fin"></a><dl>
<dt><a name="index-gnutls_005fhandshake_005fget_005flast_005fin"></a>Function: <em>gnutls_handshake_description_t</em> <strong>gnutls_handshake_get_last_in</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function is only useful to check where the last performed
handshake failed.  If the previous handshake succeed or was not
performed at all then no meaningful value will be returned.
</p>
<p>Check <code>gnutls_handshake_description_t</code>  in gnutls.h for the
available handshake descriptions.
</p>
<p><strong>Returns:</strong> the last handshake message type received, a
<code>gnutls_handshake_description_t</code> .
</p></dd></dl>

<a name="gnutls_005fhandshake_005fget_005flast_005fout-1"></a>
<h4 class="subheading">gnutls_handshake_get_last_out</h4>
<a name="gnutls_005fhandshake_005fget_005flast_005fout"></a><dl>
<dt><a name="index-gnutls_005fhandshake_005fget_005flast_005fout"></a>Function: <em>gnutls_handshake_description_t</em> <strong>gnutls_handshake_get_last_out</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function is only useful to check where the last performed
handshake failed.  If the previous handshake succeed or was not
performed at all then no meaningful value will be returned.
</p>
<p>Check <code>gnutls_handshake_description_t</code>  in gnutls.h for the
available handshake descriptions.
</p>
<p><strong>Returns:</strong> the last handshake message type sent, a
<code>gnutls_handshake_description_t</code> .
</p></dd></dl>

<a name="gnutls_005fhandshake_005fset_005fhook_005ffunction-1"></a>
<h4 class="subheading">gnutls_handshake_set_hook_function</h4>
<a name="gnutls_005fhandshake_005fset_005fhook_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fhandshake_005fset_005fhook_005ffunction"></a>Function: <em>void</em> <strong>gnutls_handshake_set_hook_function</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>htype</var>, int <var>post</var>, gnutls_handshake_hook_func <var>func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type
</p>
<p><var>htype</var>: the <code>gnutls_handshake_description_t</code>  of the message to hook at
</p>
<p><var>post</var>: <code>GNUTLS_HOOK_</code> * depending on when the hook function should be called
</p>
<p><var>func</var>: is the function to be called
</p>
<p>This function will set a callback to be called after or before the specified
handshake message has been received or generated. This is a
generalization of <code>gnutls_handshake_set_post_client_hello_function()</code> .
</p>
<p>To call the hook function prior to the message being sent/generated use
<code>GNUTLS_HOOK_PRE</code>  as  <code>post</code> parameter, <code>GNUTLS_HOOK_POST</code>  to call
after, and <code>GNUTLS_HOOK_BOTH</code>  for both cases.
</p>
<p>This callback must return 0 on success or a gnutls error code to
terminate the handshake.
</p>
<p>Note to hook at all handshake messages use an  <code>htype</code> of <code>GNUTLS_HANDSHAKE_ANY</code> .
</p>
<p><strong>Warning:</strong> You should not use this function to terminate the
handshake based on client input unless you know what you are
doing. Before the handshake is finished there is no way to know if
there is a man-in-the-middle attack being performed.
</p></dd></dl>

<a name="gnutls_005fhandshake_005fset_005fmax_005fpacket_005flength-1"></a>
<h4 class="subheading">gnutls_handshake_set_max_packet_length</h4>
<a name="gnutls_005fhandshake_005fset_005fmax_005fpacket_005flength"></a><dl>
<dt><a name="index-gnutls_005fhandshake_005fset_005fmax_005fpacket_005flength"></a>Function: <em>void</em> <strong>gnutls_handshake_set_max_packet_length</strong> <em>(gnutls_session_t <var>session</var>, size_t <var>max</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>max</var>: is the maximum number.
</p>
<p>This function will set the maximum size of all handshake messages.
Handshakes over this size are rejected with
<code>GNUTLS_E_HANDSHAKE_TOO_LARGE</code>  error code.  The default value is
48kb which is typically large enough.  Set this to 0 if you do not
want to set an upper limit.
</p>
<p>The reason for restricting the handshake message sizes are to
limit Denial of Service attacks.
</p></dd></dl>

<a name="gnutls_005fhandshake_005fset_005fpost_005fclient_005fhello_005ffunction-1"></a>
<h4 class="subheading">gnutls_handshake_set_post_client_hello_function</h4>
<a name="gnutls_005fhandshake_005fset_005fpost_005fclient_005fhello_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fhandshake_005fset_005fpost_005fclient_005fhello_005ffunction"></a>Function: <em>void</em> <strong>gnutls_handshake_set_post_client_hello_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_handshake_post_client_hello_func       <var>func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>func</var>: is the function to be called
</p>
<p>This function will set a callback to be called after the client
hello has been received (callback valid in server side only). This
allows the server to adjust settings based on received extensions.
</p>
<p>Those settings could be ciphersuites, requesting certificate, or
anything else except for version negotiation (this is done before
the hello message is parsed).
</p>
<p>This callback must return 0 on success or a gnutls error code to
terminate the handshake.
</p>
<p>Since GnuTLS 3.3.5 the callback is
allowed to return <code>GNUTLS_E_AGAIN</code>  or <code>GNUTLS_E_INTERRUPTED</code>  to
put the handshake on hold. In that case <code>gnutls_handshake()</code> 
will return <code>GNUTLS_E_INTERRUPTED</code>  and can be resumed when needed.
</p>
<p><strong>Warning:</strong> You should not use this function to terminate the
handshake based on client input unless you know what you are
doing. Before the handshake is finished there is no way to know if
there is a man-in-the-middle attack being performed.
</p></dd></dl>

<a name="gnutls_005fhandshake_005fset_005fprivate_005fextensions-1"></a>
<h4 class="subheading">gnutls_handshake_set_private_extensions</h4>
<a name="gnutls_005fhandshake_005fset_005fprivate_005fextensions"></a><dl>
<dt><a name="index-gnutls_005fhandshake_005fset_005fprivate_005fextensions"></a>Function: <em>void</em> <strong>gnutls_handshake_set_private_extensions</strong> <em>(gnutls_session_t <var>session</var>, int <var>allow</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>allow</var>: is an integer (0 or 1)
</p>
<p>This function will enable or disable the use of private cipher
suites (the ones that start with 0xFF).  By default or if  <code>allow</code> is 0 then these cipher suites will not be advertised nor used.
</p>
<p>Currently GnuTLS does not include such cipher-suites or
compression algorithms.
</p>
<p>Enabling the private ciphersuites when talking to other than
gnutls servers and clients may cause interoperability problems.
</p></dd></dl>

<a name="gnutls_005fhandshake_005fset_005frandom-1"></a>
<h4 class="subheading">gnutls_handshake_set_random</h4>
<a name="gnutls_005fhandshake_005fset_005frandom"></a><dl>
<dt><a name="index-gnutls_005fhandshake_005fset_005frandom"></a>Function: <em>int</em> <strong>gnutls_handshake_set_random</strong> <em>(gnutls_session_t <var>session</var>, const gnutls_datum_t * <var>random</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>random</var>: a random value of 32-bytes
</p>
<p>This function will explicitly set the server or client hello 
random value in the subsequent TLS handshake. The random value 
should be a 32-byte value.
</p>
<p>Note that this function should not normally be used as gnutls
will select automatically a random value for the handshake.
</p>
<p>This function should not be used when resuming a session.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p>
<p>Since 3.1.9
</p></dd></dl>

<a name="gnutls_005fhandshake_005fset_005ftimeout-1"></a>
<h4 class="subheading">gnutls_handshake_set_timeout</h4>
<a name="gnutls_005fhandshake_005fset_005ftimeout"></a><dl>
<dt><a name="index-gnutls_005fhandshake_005fset_005ftimeout-1"></a>Function: <em>void</em> <strong>gnutls_handshake_set_timeout</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>ms</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>ms</var>: is a timeout value in milliseconds
</p>
<p>This function sets the timeout for the TLS handshake process
to the provided value. Use an  <code>ms</code> value of zero to disable
timeout, or <code>GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT</code>  for a reasonable
default value. For the DTLS protocol, the more detailed
<code>gnutls_dtls_set_timeouts()</code>  is provided.
</p>
<p>This function requires to set a pull timeout callback. See
<code>gnutls_transport_set_pull_timeout_function()</code> .
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fheartbeat_005fallowed-1"></a>
<h4 class="subheading">gnutls_heartbeat_allowed</h4>
<a name="gnutls_005fheartbeat_005fallowed"></a><dl>
<dt><a name="index-gnutls_005fheartbeat_005fallowed"></a>Function: <em>int</em> <strong>gnutls_heartbeat_allowed</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>type</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>type</var>: one of <code>GNUTLS_HB_LOCAL_ALLOWED_TO_SEND</code>  and <code>GNUTLS_HB_PEER_ALLOWED_TO_SEND</code> 
</p>
<p>This function will check whether heartbeats are allowed
to be sent or received in this session. 
</p>
<p><strong>Returns:</strong> Non zero if heartbeats are allowed.
</p>
<p><strong>Since:</strong> 3.1.2
</p></dd></dl>

<a name="gnutls_005fheartbeat_005fenable-1"></a>
<h4 class="subheading">gnutls_heartbeat_enable</h4>
<a name="gnutls_005fheartbeat_005fenable"></a><dl>
<dt><a name="index-gnutls_005fheartbeat_005fenable"></a>Function: <em>void</em> <strong>gnutls_heartbeat_enable</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>type</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>type</var>: one of the GNUTLS_HB_* flags
</p>
<p>If this function is called with the <code>GNUTLS_HB_PEER_ALLOWED_TO_SEND</code> 
 <code>type</code> , GnuTLS will allow heartbeat messages to be received. Moreover it also
request the peer to accept heartbeat messages.
</p>
<p>If the  <code>type</code> used is <code>GNUTLS_HB_LOCAL_ALLOWED_TO_SEND</code> , then the peer
will be asked to accept heartbeat messages but not send ones.
</p>
<p>The function <code>gnutls_heartbeat_allowed()</code>  can be used to test Whether
locally generated heartbeat messages can be accepted by the peer.
</p>
<p><strong>Since:</strong> 3.1.2
</p></dd></dl>

<a name="gnutls_005fheartbeat_005fget_005ftimeout-1"></a>
<h4 class="subheading">gnutls_heartbeat_get_timeout</h4>
<a name="gnutls_005fheartbeat_005fget_005ftimeout"></a><dl>
<dt><a name="index-gnutls_005fheartbeat_005fget_005ftimeout"></a>Function: <em>unsigned int</em> <strong>gnutls_heartbeat_get_timeout</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function will return the milliseconds remaining
for a retransmission of the previously sent ping
message. This function is useful when ping is used in
non-blocking mode, to estimate when to call <code>gnutls_heartbeat_ping()</code> 
if no packets have been received.
</p>
<p><strong>Returns:</strong> the remaining time in milliseconds.
</p>
<p><strong>Since:</strong> 3.1.2
</p></dd></dl>

<a name="gnutls_005fheartbeat_005fping-1"></a>
<h4 class="subheading">gnutls_heartbeat_ping</h4>
<a name="gnutls_005fheartbeat_005fping"></a><dl>
<dt><a name="index-gnutls_005fheartbeat_005fping"></a>Function: <em>int</em> <strong>gnutls_heartbeat_ping</strong> <em>(gnutls_session_t <var>session</var>, size_t <var>data_size</var>, unsigned int <var>max_tries</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>data_size</var>: is the length of the ping payload.
</p>
<p><var>max_tries</var>: if flags is <code>GNUTLS_HEARTBEAT_WAIT</code>  then this sets the number of retransmissions. Use zero for indefinite (until timeout).
</p>
<p><var>flags</var>: if <code>GNUTLS_HEARTBEAT_WAIT</code>  then wait for pong or timeout instead of returning immediately.
</p>
<p>This function sends a ping to the peer. If the  <code>flags</code> is set
to <code>GNUTLS_HEARTBEAT_WAIT</code>  then it waits for a reply from the peer.
</p>
<p>Note that it is highly recommended to use this function with the
flag <code>GNUTLS_HEARTBEAT_WAIT</code> , or you need to handle retransmissions
and timeouts manually.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.1.2
</p></dd></dl>

<a name="gnutls_005fheartbeat_005fpong-1"></a>
<h4 class="subheading">gnutls_heartbeat_pong</h4>
<a name="gnutls_005fheartbeat_005fpong"></a><dl>
<dt><a name="index-gnutls_005fheartbeat_005fpong"></a>Function: <em>int</em> <strong>gnutls_heartbeat_pong</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function replies to a ping by sending a pong to the peer.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.1.2
</p></dd></dl>

<a name="gnutls_005fheartbeat_005fset_005ftimeouts-1"></a>
<h4 class="subheading">gnutls_heartbeat_set_timeouts</h4>
<a name="gnutls_005fheartbeat_005fset_005ftimeouts"></a><dl>
<dt><a name="index-gnutls_005fheartbeat_005fset_005ftimeouts"></a>Function: <em>void</em> <strong>gnutls_heartbeat_set_timeouts</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>retrans_timeout</var>, unsigned int <var>total_timeout</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>retrans_timeout</var>: The time at which a retransmission will occur in milliseconds
</p>
<p><var>total_timeout</var>: The time at which the connection will be aborted, in milliseconds.
</p>
<p>This function will override the timeouts for the DTLS heartbeat
protocol. The retransmission timeout is the time after which a
message from the peer is not received, the previous request will
be retransmitted. The total timeout is the time after which the
handshake will be aborted with <code>GNUTLS_E_TIMEDOUT</code> .
</p>
<p><strong>Since:</strong> 3.1.2
</p></dd></dl>

<a name="gnutls_005fhex2bin-1"></a>
<h4 class="subheading">gnutls_hex2bin</h4>
<a name="gnutls_005fhex2bin"></a><dl>
<dt><a name="index-gnutls_005fhex2bin"></a>Function: <em>int</em> <strong>gnutls_hex2bin</strong> <em>(const char * <var>hex_data</var>, size_t <var>hex_size</var>, void * <var>bin_data</var>, size_t * <var>bin_size</var>)</em></dt>
<dd><p><var>hex_data</var>: string with data in hex format
</p>
<p><var>hex_size</var>: size of hex data
</p>
<p><var>bin_data</var>: output array with binary data
</p>
<p><var>bin_size</var>: when calling should hold maximum size of  <code>bin_data</code> ,
on return will hold actual length of  <code>bin_data</code> .
</p>
<p>Convert a buffer with hex data to binary data. This function
unlike <code>gnutls_hex_decode()</code>  can parse hex data with separators
between numbers. That is, it ignores any non-hex characters.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fhex_005fdecode-1"></a>
<h4 class="subheading">gnutls_hex_decode</h4>
<a name="gnutls_005fhex_005fdecode"></a><dl>
<dt><a name="index-gnutls_005fhex_005fdecode"></a>Function: <em>int</em> <strong>gnutls_hex_decode</strong> <em>(const gnutls_datum_t * <var>hex_data</var>, void * <var>result</var>, size_t * <var>result_size</var>)</em></dt>
<dd><p><var>hex_data</var>: contain the encoded data
</p>
<p><var>result</var>: the place where decoded data will be copied
</p>
<p><var>result_size</var>: holds the size of the result
</p>
<p>This function will decode the given encoded data, using the hex
encoding used by PSK password files.
</p>
<p>Initially  <code>result_size</code> must hold the maximum size available in
 <code>result</code> , and on return it will contain the number of bytes written.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the buffer given is not
long enough, <code>GNUTLS_E_PARSING_ERROR</code>  on invalid hex data, or 0 on success.
</p></dd></dl>

<a name="gnutls_005fhex_005fdecode2-1"></a>
<h4 class="subheading">gnutls_hex_decode2</h4>
<a name="gnutls_005fhex_005fdecode2"></a><dl>
<dt><a name="index-gnutls_005fhex_005fdecode2"></a>Function: <em>int</em> <strong>gnutls_hex_decode2</strong> <em>(const gnutls_datum_t * <var>hex_data</var>, gnutls_datum_t * <var>result</var>)</em></dt>
<dd><p><var>hex_data</var>: contain the encoded data
</p>
<p><var>result</var>: the result in an allocated string
</p>
<p>This function will decode the given encoded data, using the hex
encoding used by PSK password files.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_PARSING_ERROR</code>  on invalid hex data, or 0 on success.
</p></dd></dl>

<a name="gnutls_005fhex_005fencode-1"></a>
<h4 class="subheading">gnutls_hex_encode</h4>
<a name="gnutls_005fhex_005fencode"></a><dl>
<dt><a name="index-gnutls_005fhex_005fencode"></a>Function: <em>int</em> <strong>gnutls_hex_encode</strong> <em>(const gnutls_datum_t * <var>data</var>, char * <var>result</var>, size_t * <var>result_size</var>)</em></dt>
<dd><p><var>data</var>: contain the raw data
</p>
<p><var>result</var>: the place where hex data will be copied
</p>
<p><var>result_size</var>: holds the size of the result
</p>
<p>This function will convert the given data to printable data, using
the hex encoding, as used in the PSK password files.
</p>
<p>Note that the size of the result includes the null terminator.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the buffer given is not
long enough, or 0 on success.
</p></dd></dl>

<a name="gnutls_005fhex_005fencode2-1"></a>
<h4 class="subheading">gnutls_hex_encode2</h4>
<a name="gnutls_005fhex_005fencode2"></a><dl>
<dt><a name="index-gnutls_005fhex_005fencode2"></a>Function: <em>int</em> <strong>gnutls_hex_encode2</strong> <em>(const gnutls_datum_t * <var>data</var>, gnutls_datum_t * <var>result</var>)</em></dt>
<dd><p><var>data</var>: contain the raw data
</p>
<p><var>result</var>: the result in an allocated string
</p>
<p>This function will convert the given data to printable data, using
the hex encoding, as used in the PSK password files.
</p>
<p>Note that the size of the result does NOT include the null terminator.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p></dd></dl>

<a name="gnutls_005finit-1"></a>
<h4 class="subheading">gnutls_init</h4>
<a name="gnutls_005finit"></a><dl>
<dt><a name="index-gnutls_005finit-1"></a>Function: <em>int</em> <strong>gnutls_init</strong> <em>(gnutls_session_t * <var>session</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>session</var>: is a pointer to a <code>gnutls_session_t</code>  type.
</p>
<p><var>flags</var>: indicate if this session is to be used for server or client.
</p>
<p>This function initializes the current session to null. Every
session must be initialized before use, so internal structures can
be allocated.  This function allocates structures which can only
be free&rsquo;d by calling <code>gnutls_deinit()</code> .  Returns <code>GNUTLS_E_SUCCESS</code>  (0) on success.
</p>
<p><code>flags</code> can be one of <code>GNUTLS_CLIENT</code> , <code>GNUTLS_SERVER</code> , <code>GNUTLS_DATAGRAM</code> ,
<code>GNUTLS_NONBLOCK</code>  or <code>GNUTLS_NOSIGNAL</code>  (since 3.4.2).
</p>
<p>The flag <code>GNUTLS_NO_REPLAY_PROTECTION</code>  will disable any 
replay protection in DTLS mode. That must only used when 
replay protection is achieved using other means.
</p>
<p>Note that since version 3.1.2 this function enables some common
TLS extensions such as session tickets and OCSP certificate status
request in client side by default. To prevent that use the <code>GNUTLS_NO_EXTENSIONS</code> 
flag.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fkey_005fgenerate-1"></a>
<h4 class="subheading">gnutls_key_generate</h4>
<a name="gnutls_005fkey_005fgenerate"></a><dl>
<dt><a name="index-gnutls_005fkey_005fgenerate"></a>Function: <em>int</em> <strong>gnutls_key_generate</strong> <em>(gnutls_datum_t * <var>key</var>, unsigned int <var>key_size</var>)</em></dt>
<dd><p><var>key</var>: is a pointer to a <code>gnutls_datum_t</code>  which will contain a newly
created key
</p>
<p><var>key_size</var>: the number of bytes of the key
</p>
<p>Generates a random key of  <code>key_size</code> bytes.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fkx_005fget-1"></a>
<h4 class="subheading">gnutls_kx_get</h4>
<a name="gnutls_005fkx_005fget"></a><dl>
<dt><a name="index-gnutls_005fkx_005fget"></a>Function: <em>gnutls_kx_algorithm_t</em> <strong>gnutls_kx_get</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Get currently used key exchange algorithm.
</p>
<p><strong>Returns:</strong> the key exchange algorithm used in the last handshake, a
<code>gnutls_kx_algorithm_t</code>  value.
</p></dd></dl>

<a name="gnutls_005fkx_005fget_005fid-1"></a>
<h4 class="subheading">gnutls_kx_get_id</h4>
<a name="gnutls_005fkx_005fget_005fid"></a><dl>
<dt><a name="index-gnutls_005fkx_005fget_005fid"></a>Function: <em>gnutls_kx_algorithm_t</em> <strong>gnutls_kx_get_id</strong> <em>(const char * <var>name</var>)</em></dt>
<dd><p><var>name</var>: is a KX name
</p>
<p>Convert a string to a <code>gnutls_kx_algorithm_t</code>  value.  The names are
compared in a case insensitive way.
</p>
<p><strong>Returns:</strong> an id of the specified KX algorithm, or <code>GNUTLS_KX_UNKNOWN</code> 
on error.
</p></dd></dl>

<a name="gnutls_005fkx_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_kx_get_name</h4>
<a name="gnutls_005fkx_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fkx_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_kx_get_name</strong> <em>(gnutls_kx_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is a key exchange algorithm
</p>
<p>Convert a <code>gnutls_kx_algorithm_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a pointer to a string that contains the name of the
specified key exchange algorithm, or <code>NULL</code> .
</p></dd></dl>

<a name="gnutls_005fkx_005flist-1"></a>
<h4 class="subheading">gnutls_kx_list</h4>
<a name="gnutls_005fkx_005flist"></a><dl>
<dt><a name="index-gnutls_005fkx_005flist"></a>Function: <em>const gnutls_kx_algorithm_t *</em> <strong>gnutls_kx_list</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>Get a list of supported key exchange algorithms.
</p>
<p>This function is not thread safe.
</p>
<p><strong>Returns:</strong> a (0)-terminated list of <code>gnutls_kx_algorithm_t</code>  integers
indicating the available key exchange algorithms.
</p></dd></dl>

<a name="gnutls_005fload_005ffile-1"></a>
<h4 class="subheading">gnutls_load_file</h4>
<a name="gnutls_005fload_005ffile"></a><dl>
<dt><a name="index-gnutls_005fload_005ffile"></a>Function: <em>int</em> <strong>gnutls_load_file</strong> <em>(const char * <var>filename</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>filename</var>: the name of the file to load
</p>
<p><var>data</var>: Where the file will be stored
</p>
<p>This function will load a file into a datum. The data are
zero terminated but the terminating null is not included in length.
The returned data are allocated using <code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p>
<p>Since 3.1.0
</p></dd></dl>

<a name="gnutls_005fmac_005fget-1"></a>
<h4 class="subheading">gnutls_mac_get</h4>
<a name="gnutls_005fmac_005fget"></a><dl>
<dt><a name="index-gnutls_005fmac_005fget"></a>Function: <em>gnutls_mac_algorithm_t</em> <strong>gnutls_mac_get</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Get currently used MAC algorithm.
</p>
<p><strong>Returns:</strong> the currently used mac algorithm, a
<code>gnutls_mac_algorithm_t</code>  value.
</p></dd></dl>

<a name="gnutls_005fmac_005fget_005fid-1"></a>
<h4 class="subheading">gnutls_mac_get_id</h4>
<a name="gnutls_005fmac_005fget_005fid"></a><dl>
<dt><a name="index-gnutls_005fmac_005fget_005fid"></a>Function: <em>gnutls_mac_algorithm_t</em> <strong>gnutls_mac_get_id</strong> <em>(const char * <var>name</var>)</em></dt>
<dd><p><var>name</var>: is a MAC algorithm name
</p>
<p>Convert a string to a <code>gnutls_mac_algorithm_t</code>  value.  The names are
compared in a case insensitive way.
</p>
<p><strong>Returns:</strong> a <code>gnutls_mac_algorithm_t</code>  id of the specified MAC
algorithm string, or <code>GNUTLS_MAC_UNKNOWN</code>  on failure.
</p></dd></dl>

<a name="gnutls_005fmac_005fget_005fkey_005fsize-1"></a>
<h4 class="subheading">gnutls_mac_get_key_size</h4>
<a name="gnutls_005fmac_005fget_005fkey_005fsize"></a><dl>
<dt><a name="index-gnutls_005fmac_005fget_005fkey_005fsize"></a>Function: <em>size_t</em> <strong>gnutls_mac_get_key_size</strong> <em>(gnutls_mac_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is an encryption algorithm
</p>
<p>Returns the size of the MAC key used in TLS. 
</p>
<p><strong>Returns:</strong> length (in bytes) of the given MAC key size, or 0 if the
given MAC algorithm is invalid.
</p></dd></dl>

<a name="gnutls_005fmac_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_mac_get_name</h4>
<a name="gnutls_005fmac_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fmac_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_mac_get_name</strong> <em>(gnutls_mac_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is a MAC algorithm
</p>
<p>Convert a <code>gnutls_mac_algorithm_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified MAC
algorithm, or <code>NULL</code> .
</p></dd></dl>

<a name="gnutls_005fmac_005flist-1"></a>
<h4 class="subheading">gnutls_mac_list</h4>
<a name="gnutls_005fmac_005flist"></a><dl>
<dt><a name="index-gnutls_005fmac_005flist"></a>Function: <em>const gnutls_mac_algorithm_t *</em> <strong>gnutls_mac_list</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>Get a list of hash algorithms for use as MACs.  Note that not
necessarily all MACs are supported in TLS cipher suites.  
This function is not thread safe.
</p>
<p><strong>Returns:</strong> Return a (0)-terminated list of <code>gnutls_mac_algorithm_t</code> 
integers indicating the available MACs.
</p></dd></dl>

<a name="gnutls_005fmemcmp-1"></a>
<h4 class="subheading">gnutls_memcmp</h4>
<a name="gnutls_005fmemcmp"></a><dl>
<dt><a name="index-gnutls_005fmemcmp"></a>Function: <em>int</em> <strong>gnutls_memcmp</strong> <em>(const void * <var>s1</var>, const void * <var>s2</var>, size_t <var>n</var>)</em></dt>
<dd><p><var>s1</var>: the first address to compare
</p>
<p><var>s2</var>: the second address to compare
</p>
<p><var>n</var>: the size of memory to compare
</p>
<p>This function will operate similarly to <code>memcmp()</code> , but will operate
on time that depends only on the size of the string. That is will
not return early if the strings don&rsquo;t match on the first byte.
</p>
<p><strong>Returns:</strong> non zero on difference and zero if the buffers are identical.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fmemset-1"></a>
<h4 class="subheading">gnutls_memset</h4>
<a name="gnutls_005fmemset"></a><dl>
<dt><a name="index-gnutls_005fmemset"></a>Function: <em>void</em> <strong>gnutls_memset</strong> <em>(void * <var>data</var>, int <var>c</var>, size_t <var>size</var>)</em></dt>
<dd><p><var>data</var>: the memory to set
</p>
<p><var>c</var>: the constant byte to fill the memory with
</p>
<p><var>size</var>: the size of memory
</p>
<p>This function will operate similarly to <code>memset()</code> , but will
not be optimized out by the compiler.
</p>
<p><strong>Returns:</strong> void.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005focsp_005fstatus_005frequest_005fenable_005fclient-1"></a>
<h4 class="subheading">gnutls_ocsp_status_request_enable_client</h4>
<a name="gnutls_005focsp_005fstatus_005frequest_005fenable_005fclient"></a><dl>
<dt><a name="index-gnutls_005focsp_005fstatus_005frequest_005fenable_005fclient"></a>Function: <em>int</em> <strong>gnutls_ocsp_status_request_enable_client</strong> <em>(gnutls_session_t <var>session</var>, gnutls_datum_t * <var>responder_id</var>, size_t <var>responder_id_size</var>, gnutls_datum_t * <var>extensions</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>responder_id</var>: array with <code>gnutls_datum_t</code>  with DER data of responder id
</p>
<p><var>responder_id_size</var>: number of members in  <code>responder_id</code> array
</p>
<p><var>extensions</var>: a <code>gnutls_datum_t</code>  with DER encoded OCSP extensions
</p>
<p>This function is to be used by clients to request OCSP response
from the server, using the &quot;status_request&quot; TLS extension.  Only
OCSP status type is supported. A typical server has a single
OCSP response cached, so  <code>responder_id</code> and  <code>extensions</code> should be null.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005focsp_005fstatus_005frequest_005fget-1"></a>
<h4 class="subheading">gnutls_ocsp_status_request_get</h4>
<a name="gnutls_005focsp_005fstatus_005frequest_005fget"></a><dl>
<dt><a name="index-gnutls_005focsp_005fstatus_005frequest_005fget"></a>Function: <em>int</em> <strong>gnutls_ocsp_status_request_get</strong> <em>(gnutls_session_t <var>session</var>, gnutls_datum_t * <var>response</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>response</var>: a <code>gnutls_datum_t</code>  with DER encoded OCSP response
</p>
<p>This function returns the OCSP status response received
from the TLS server. The  <code>response</code> should be treated as
constant. If no OCSP response is available then
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005focsp_005fstatus_005frequest_005fis_005fchecked-1"></a>
<h4 class="subheading">gnutls_ocsp_status_request_is_checked</h4>
<a name="gnutls_005focsp_005fstatus_005frequest_005fis_005fchecked"></a><dl>
<dt><a name="index-gnutls_005focsp_005fstatus_005frequest_005fis_005fchecked"></a>Function: <em>int</em> <strong>gnutls_ocsp_status_request_is_checked</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p><var>flags</var>: should be zero or <code>GNUTLS_OCSP_SR_IS_AVAIL</code> 
</p>
<p>Check whether an OCSP status response was included in the handshake
and whether it was checked and valid (not too old or superseded). 
This is a helper function when needing to decide whether to perform an
OCSP validity check on the peer&rsquo;s certificate. Should be called after
any of gnutls_certificate_verify_peers*() are called.
</p>
<p>If the flag <code>GNUTLS_OCSP_SR_IS_AVAIL</code>  is specified, the return
value of the function indicates whether an OCSP status response have
been received (even if invalid).
</p>
<p><strong>Returns:</strong> non zero if the response was valid, or a zero if it wasn&rsquo;t sent,
or sent and was invalid.
</p></dd></dl>

<a name="gnutls_005foid_005fto_005fdigest-1"></a>
<h4 class="subheading">gnutls_oid_to_digest</h4>
<a name="gnutls_005foid_005fto_005fdigest"></a><dl>
<dt><a name="index-gnutls_005foid_005fto_005fdigest"></a>Function: <em>gnutls_digest_algorithm_t</em> <strong>gnutls_oid_to_digest</strong> <em>(const char * <var>oid</var>)</em></dt>
<dd><p><var>oid</var>: is an object identifier
</p>
<p>Converts a textual object identifier to a <code>gnutls_digest_algorithm_t</code>  value.
</p>
<p><strong>Returns:</strong> a <code>gnutls_digest_algorithm_t</code>  id of the specified digest
algorithm, or <code>GNUTLS_DIG_UNKNOWN</code>  on failure.
</p>
<p><strong>Since:</strong> 3.4.3
</p></dd></dl>

<a name="gnutls_005foid_005fto_005fecc_005fcurve-1"></a>
<h4 class="subheading">gnutls_oid_to_ecc_curve</h4>
<a name="gnutls_005foid_005fto_005fecc_005fcurve"></a><dl>
<dt><a name="index-gnutls_005foid_005fto_005fecc_005fcurve"></a>Function: <em>gnutls_ecc_curve_t</em> <strong>gnutls_oid_to_ecc_curve</strong> <em>(const char * <var>oid</var>)</em></dt>
<dd><p><var>oid</var>: is a curve&rsquo;s OID
</p>

<p><strong>Returns:</strong> return a <code>gnutls_ecc_curve_t</code>  value corresponding to
the specified OID, or <code>GNUTLS_ECC_CURVE_INVALID</code>  on error.
</p>
<p><strong>Since:</strong> 3.4.3
</p></dd></dl>

<a name="gnutls_005foid_005fto_005fpk-1"></a>
<h4 class="subheading">gnutls_oid_to_pk</h4>
<a name="gnutls_005foid_005fto_005fpk"></a><dl>
<dt><a name="index-gnutls_005foid_005fto_005fpk"></a>Function: <em>gnutls_pk_algorithm_t</em> <strong>gnutls_oid_to_pk</strong> <em>(const char * <var>oid</var>)</em></dt>
<dd><p><var>oid</var>: is an object identifier
</p>
<p>Converts a textual object identifier to a <code>gnutls_pk_algorithm_t</code>  value.
</p>
<p><strong>Returns:</strong> a <code>gnutls_pk_algorithm_t</code>  id of the specified digest
algorithm, or <code>GNUTLS_PK_UNKNOWN</code>  on failure.
</p>
<p><strong>Since:</strong> 3.4.3
</p></dd></dl>

<a name="gnutls_005foid_005fto_005fsign-1"></a>
<h4 class="subheading">gnutls_oid_to_sign</h4>
<a name="gnutls_005foid_005fto_005fsign"></a><dl>
<dt><a name="index-gnutls_005foid_005fto_005fsign"></a>Function: <em>gnutls_sign_algorithm_t</em> <strong>gnutls_oid_to_sign</strong> <em>(const char * <var>oid</var>)</em></dt>
<dd><p><var>oid</var>: is an object identifier
</p>
<p>Converts a textual object identifier to a <code>gnutls_sign_algorithm_t</code>  value.
</p>
<p><strong>Returns:</strong> a <code>gnutls_sign_algorithm_t</code>  id of the specified digest
algorithm, or <code>GNUTLS_SIGN_UNKNOWN</code>  on failure.
</p>
<p><strong>Since:</strong> 3.4.3
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fsend_005fcert-1"></a>
<h4 class="subheading">gnutls_openpgp_send_cert</h4>
<a name="gnutls_005fopenpgp_005fsend_005fcert"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fsend_005fcert"></a>Function: <em>void</em> <strong>gnutls_openpgp_send_cert</strong> <em>(gnutls_session_t <var>session</var>, gnutls_openpgp_crt_status_t <var>status</var>)</em></dt>
<dd><p><var>session</var>: a <code>gnutls_session_t</code>  type.
</p>
<p><var>status</var>: is one of GNUTLS_OPENPGP_CERT, or GNUTLS_OPENPGP_CERT_FINGERPRINT
</p>
<p>This function will order gnutls to send the key fingerprint
instead of the key in the initial handshake procedure. This should
be used with care and only when there is indication or knowledge
that the server can obtain the client&rsquo;s key.
</p></dd></dl>

<a name="gnutls_005fpacket_005fdeinit-1"></a>
<h4 class="subheading">gnutls_packet_deinit</h4>
<a name="gnutls_005fpacket_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fpacket_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_packet_deinit</strong> <em>(gnutls_packet_t <var>packet</var>)</em></dt>
<dd><p><var>packet</var>: is a pointer to a <code>gnutls_packet_st</code>  structure.
</p>
<p>This function will deinitialize all data associated with
the received packet.
</p>
<p><strong>Since:</strong> 3.3.5
</p></dd></dl>

<a name="gnutls_005fpacket_005fget-1"></a>
<h4 class="subheading">gnutls_packet_get</h4>
<a name="gnutls_005fpacket_005fget"></a><dl>
<dt><a name="index-gnutls_005fpacket_005fget"></a>Function: <em>void</em> <strong>gnutls_packet_get</strong> <em>(gnutls_packet_t <var>packet</var>, gnutls_datum_t * <var>data</var>, unsigned char * <var>sequence</var>)</em></dt>
<dd><p><var>packet</var>: is a <code>gnutls_packet_t</code>  type.
</p>
<p><var>data</var>: will contain the data present in the  <code>packet</code> structure (may be <code>NULL</code> )
</p>
<p><var>sequence</var>: the 8-bytes of the packet sequence number (may be <code>NULL</code> )
</p>
<p>This function returns the data and sequence number associated with
the received packet.
</p>
<p><strong>Since:</strong> 3.3.5
</p></dd></dl>

<a name="gnutls_005fpem_005fbase64_005fdecode-1"></a>
<h4 class="subheading">gnutls_pem_base64_decode</h4>
<a name="gnutls_005fpem_005fbase64_005fdecode"></a><dl>
<dt><a name="index-gnutls_005fpem_005fbase64_005fdecode"></a>Function: <em>int</em> <strong>gnutls_pem_base64_decode</strong> <em>(const char * <var>header</var>, const gnutls_datum_t * <var>b64_data</var>, unsigned char * <var>result</var>, size_t * <var>result_size</var>)</em></dt>
<dd><p><var>header</var>: A null terminated string with the PEM header (eg. CERTIFICATE)
</p>
<p><var>b64_data</var>: contain the encoded data
</p>
<p><var>result</var>: the place where decoded data will be copied
</p>
<p><var>result_size</var>: holds the size of the result
</p>
<p>This function will decode the given encoded data.  If the header
given is non null this function will search for &quot;&mdash;&ndash;BEGIN header&quot;
and decode only this part.  Otherwise it will decode the first PEM
packet found.
</p>
<p><strong>Returns:</strong> On success <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  is returned if the buffer given is
not long enough, or 0 on success.
</p></dd></dl>

<a name="gnutls_005fpem_005fbase64_005fdecode2-1"></a>
<h4 class="subheading">gnutls_pem_base64_decode2</h4>
<a name="gnutls_005fpem_005fbase64_005fdecode2"></a><dl>
<dt><a name="index-gnutls_005fpem_005fbase64_005fdecode2"></a>Function: <em>int</em> <strong>gnutls_pem_base64_decode2</strong> <em>(const char * <var>header</var>, const gnutls_datum_t * <var>b64_data</var>, gnutls_datum_t * <var>result</var>)</em></dt>
<dd><p><var>header</var>: The PEM header (eg. CERTIFICATE)
</p>
<p><var>b64_data</var>: contains the encoded data
</p>
<p><var>result</var>: the place where decoded data lie
</p>
<p>This function will decode the given encoded data. The decoded data
will be allocated, and stored into result.  If the header given is
non null this function will search for &quot;&mdash;&ndash;BEGIN header&quot; and
decode only this part. Otherwise it will decode the first PEM
packet found.
</p>
<p>You should use <code>gnutls_free()</code>  to free the returned data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fpem_005fbase64_005fencode-1"></a>
<h4 class="subheading">gnutls_pem_base64_encode</h4>
<a name="gnutls_005fpem_005fbase64_005fencode"></a><dl>
<dt><a name="index-gnutls_005fpem_005fbase64_005fencode"></a>Function: <em>int</em> <strong>gnutls_pem_base64_encode</strong> <em>(const char * <var>msg</var>, const gnutls_datum_t * <var>data</var>, char * <var>result</var>, size_t * <var>result_size</var>)</em></dt>
<dd><p><var>msg</var>: is a message to be put in the header
</p>
<p><var>data</var>: contain the raw data
</p>
<p><var>result</var>: the place where base64 data will be copied
</p>
<p><var>result_size</var>: holds the size of the result
</p>
<p>This function will convert the given data to printable data, using
the base64 encoding. This is the encoding used in PEM messages.
</p>
<p>The output string will be null terminated, although the size will
not include the terminating null.
</p>
<p><strong>Returns:</strong> On success <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  is returned if the buffer given is
not long enough, or 0 on success.
</p></dd></dl>

<a name="gnutls_005fpem_005fbase64_005fencode2-1"></a>
<h4 class="subheading">gnutls_pem_base64_encode2</h4>
<a name="gnutls_005fpem_005fbase64_005fencode2"></a><dl>
<dt><a name="index-gnutls_005fpem_005fbase64_005fencode2"></a>Function: <em>int</em> <strong>gnutls_pem_base64_encode2</strong> <em>(const char * <var>msg</var>, const gnutls_datum_t * <var>data</var>, gnutls_datum_t * <var>result</var>)</em></dt>
<dd><p><var>msg</var>: is a message to be put in the encoded header
</p>
<p><var>data</var>: contains the raw data
</p>
<p><var>result</var>: will hold the newly allocated encoded data
</p>
<p>This function will convert the given data to printable data, using
the base64 encoding.  This is the encoding used in PEM messages.
This function will allocate the required memory to hold the encoded
data.
</p>
<p>You should use <code>gnutls_free()</code>  to free the returned data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fperror-1"></a>
<h4 class="subheading">gnutls_perror</h4>
<a name="gnutls_005fperror"></a><dl>
<dt><a name="index-gnutls_005fperror"></a>Function: <em>void</em> <strong>gnutls_perror</strong> <em>(int <var>error</var>)</em></dt>
<dd><p><var>error</var>: is a GnuTLS error code, a negative error code
</p>
<p>This function is like <code>perror()</code> . The only difference is that it
accepts an error number returned by a gnutls function.
</p></dd></dl>

<a name="gnutls_005fpk_005falgorithm_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_pk_algorithm_get_name</h4>
<a name="gnutls_005fpk_005falgorithm_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fpk_005falgorithm_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_pk_algorithm_get_name</strong> <em>(gnutls_pk_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is a pk algorithm
</p>
<p>Convert a <code>gnutls_pk_algorithm_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified public
key algorithm, or <code>NULL</code> .
</p></dd></dl>

<a name="gnutls_005fpk_005fbits_005fto_005fsec_005fparam-1"></a>
<h4 class="subheading">gnutls_pk_bits_to_sec_param</h4>
<a name="gnutls_005fpk_005fbits_005fto_005fsec_005fparam"></a><dl>
<dt><a name="index-gnutls_005fpk_005fbits_005fto_005fsec_005fparam-1"></a>Function: <em>gnutls_sec_param_t</em> <strong>gnutls_pk_bits_to_sec_param</strong> <em>(gnutls_pk_algorithm_t <var>algo</var>, unsigned int <var>bits</var>)</em></dt>
<dd><p><var>algo</var>: is a public key algorithm
</p>
<p><var>bits</var>: is the number of bits
</p>
<p>This is the inverse of <code>gnutls_sec_param_to_pk_bits()</code> . Given an algorithm
and the number of bits, it will return the security parameter. This is
a rough indication.
</p>
<p><strong>Returns:</strong> The security parameter.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpk_005fget_005fid-1"></a>
<h4 class="subheading">gnutls_pk_get_id</h4>
<a name="gnutls_005fpk_005fget_005fid"></a><dl>
<dt><a name="index-gnutls_005fpk_005fget_005fid"></a>Function: <em>gnutls_pk_algorithm_t</em> <strong>gnutls_pk_get_id</strong> <em>(const char * <var>name</var>)</em></dt>
<dd><p><var>name</var>: is a string containing a public key algorithm name.
</p>
<p>Convert a string to a <code>gnutls_pk_algorithm_t</code>  value.  The names are
compared in a case insensitive way.  For example,
gnutls_pk_get_id(&quot;RSA&quot;) will return <code>GNUTLS_PK_RSA</code> .
</p>
<p><strong>Returns:</strong> a <code>gnutls_pk_algorithm_t</code>  id of the specified public key
algorithm string, or <code>GNUTLS_PK_UNKNOWN</code>  on failures.
</p>
<p><strong>Since:</strong> 2.6.0
</p></dd></dl>

<a name="gnutls_005fpk_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_pk_get_name</h4>
<a name="gnutls_005fpk_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fpk_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_pk_get_name</strong> <em>(gnutls_pk_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is a public key algorithm
</p>
<p>Convert a <code>gnutls_pk_algorithm_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a pointer to a string that contains the name of the
specified public key algorithm, or <code>NULL</code> .
</p>
<p><strong>Since:</strong> 2.6.0
</p></dd></dl>

<a name="gnutls_005fpk_005fget_005foid-1"></a>
<h4 class="subheading">gnutls_pk_get_oid</h4>
<a name="gnutls_005fpk_005fget_005foid"></a><dl>
<dt><a name="index-gnutls_005fpk_005fget_005foid"></a>Function: <em>const char *</em> <strong>gnutls_pk_get_oid</strong> <em>(gnutls_pk_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is a public key algorithm
</p>
<p>Convert a <code>gnutls_pk_algorithm_t</code>  value to its object identifier string.
</p>
<p><strong>Returns:</strong> a pointer to a string that contains the object identifier of the
specified public key algorithm, or <code>NULL</code> .
</p>
<p><strong>Since:</strong> 3.4.3
</p></dd></dl>

<a name="gnutls_005fpk_005flist-1"></a>
<h4 class="subheading">gnutls_pk_list</h4>
<a name="gnutls_005fpk_005flist"></a><dl>
<dt><a name="index-gnutls_005fpk_005flist"></a>Function: <em>const gnutls_pk_algorithm_t *</em> <strong>gnutls_pk_list</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>Get a list of supported public key algorithms.
</p>
<p>This function is not thread safe.
</p>
<p><strong>Returns:</strong> a (0)-terminated list of <code>gnutls_pk_algorithm_t</code>  integers
indicating the available ciphers.
</p>
<p><strong>Since:</strong> 2.6.0
</p></dd></dl>

<a name="gnutls_005fpk_005fto_005fsign-1"></a>
<h4 class="subheading">gnutls_pk_to_sign</h4>
<a name="gnutls_005fpk_005fto_005fsign"></a><dl>
<dt><a name="index-gnutls_005fpk_005fto_005fsign"></a>Function: <em>gnutls_sign_algorithm_t</em> <strong>gnutls_pk_to_sign</strong> <em>(gnutls_pk_algorithm_t <var>pk</var>, gnutls_digest_algorithm_t <var>hash</var>)</em></dt>
<dd><p><var>pk</var>: is a public key algorithm
</p>
<p><var>hash</var>: a hash algorithm
</p>
<p>This function maps public key and hash algorithms combinations
to signature algorithms.
</p>
<p><strong>Returns:</strong> return a <code>gnutls_sign_algorithm_t</code>  value, or <code>GNUTLS_SIGN_UNKNOWN</code>  on error.
</p></dd></dl>

<a name="gnutls_005fprf-1"></a>
<h4 class="subheading">gnutls_prf</h4>
<a name="gnutls_005fprf"></a><dl>
<dt><a name="index-gnutls_005fprf"></a>Function: <em>int</em> <strong>gnutls_prf</strong> <em>(gnutls_session_t <var>session</var>, size_t <var>label_size</var>, const char * <var>label</var>, int <var>server_random_first</var>, size_t <var>extra_size</var>, const char * <var>extra</var>, size_t <var>outsize</var>, char * <var>out</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>label_size</var>: length of the  <code>label</code> variable.
</p>
<p><var>label</var>: label used in PRF computation, typically a short string.
</p>
<p><var>server_random_first</var>: non-zero if server random field should be first in seed
</p>
<p><var>extra_size</var>: length of the  <code>extra</code> variable.
</p>
<p><var>extra</var>: optional extra data to seed the PRF with.
</p>
<p><var>outsize</var>: size of pre-allocated output buffer to hold the output.
</p>
<p><var>out</var>: pre-allocated buffer to hold the generated data.
</p>
<p>Applies the TLS Pseudo-Random-Function (PRF) on the master secret
and the provided data, seeded with the client and server random fields.
For the key expansion specified in RFC5705 see <code>gnutls_prf_rfc5705()</code> .
</p>
<p>The  <code>label</code> variable usually contains a string denoting the purpose
for the generated data.  The  <code>server_random_first</code> indicates whether
the client random field or the server random field should be first
in the seed.  Non-zero indicates that the server random field is first,
0 that the client random field is first.
</p>
<p>The  <code>extra</code> variable can be used to add more data to the seed, after
the random variables.  It can be used to make sure the
generated output is strongly connected to some additional data
(e.g., a string used in user authentication).
</p>
<p>The output is placed in  <code>out</code> , which must be pre-allocated.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fprf_005fraw-1"></a>
<h4 class="subheading">gnutls_prf_raw</h4>
<a name="gnutls_005fprf_005fraw"></a><dl>
<dt><a name="index-gnutls_005fprf_005fraw"></a>Function: <em>int</em> <strong>gnutls_prf_raw</strong> <em>(gnutls_session_t <var>session</var>, size_t <var>label_size</var>, const char * <var>label</var>, size_t <var>seed_size</var>, const char * <var>seed</var>, size_t <var>outsize</var>, char * <var>out</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>label_size</var>: length of the  <code>label</code> variable.
</p>
<p><var>label</var>: label used in PRF computation, typically a short string.
</p>
<p><var>seed_size</var>: length of the  <code>seed</code> variable.
</p>
<p><var>seed</var>: optional extra data to seed the PRF with.
</p>
<p><var>outsize</var>: size of pre-allocated output buffer to hold the output.
</p>
<p><var>out</var>: pre-allocated buffer to hold the generated data.
</p>
<p>Apply the TLS Pseudo-Random-Function (PRF) on the master secret
and the provided data.
</p>
<p>The  <code>label</code> variable usually contains a string denoting the purpose
for the generated data.  The  <code>seed</code> usually contains data such as the
client and server random, perhaps together with some additional
data that is added to guarantee uniqueness of the output for a
particular purpose.
</p>
<p>Because the output is not guaranteed to be unique for a particular
session unless  <code>seed</code> includes the client random and server random
fields (the PRF would output the same data on another connection
resumed from the first one), it is not recommended to use this
function directly.  The <code>gnutls_prf()</code>  function seeds the PRF with the
client and server random fields directly, and is recommended if you
want to generate pseudo random data unique for each session.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fprf_005frfc5705-1"></a>
<h4 class="subheading">gnutls_prf_rfc5705</h4>
<a name="gnutls_005fprf_005frfc5705"></a><dl>
<dt><a name="index-gnutls_005fprf_005frfc5705"></a>Function: <em>int</em> <strong>gnutls_prf_rfc5705</strong> <em>(gnutls_session_t <var>session</var>, size_t <var>label_size</var>, const char * <var>label</var>, size_t <var>context_size</var>, const char * <var>context</var>, size_t <var>outsize</var>, char * <var>out</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>label_size</var>: length of the  <code>label</code> variable.
</p>
<p><var>label</var>: label used in PRF computation, typically a short string.
</p>
<p><var>context_size</var>: length of the  <code>extra</code> variable.
</p>
<p><var>context</var>: optional extra data to seed the PRF with.
</p>
<p><var>outsize</var>: size of pre-allocated output buffer to hold the output.
</p>
<p><var>out</var>: pre-allocated buffer to hold the generated data.
</p>
<p>Applies the TLS Pseudo-Random-Function (PRF) on the master secret
and the provided data, seeded with the client and server random fields,
as specified in RFC5705.
</p>
<p>The  <code>label</code> variable usually contains a string denoting the purpose
for the generated data.  The  <code>server_random_first</code> indicates whether
the client random field or the server random field should be first
in the seed.  Non-zero indicates that the server random field is first,
0 that the client random field is first.
</p>
<p>The  <code>context</code> variable can be used to add more data to the seed, after
the random variables.  It can be used to make sure the
generated output is strongly connected to some additional data
(e.g., a string used in user authentication). 
</p>
<p>The output is placed in  <code>out</code> , which must be pre-allocated.
</p>
<p>Note that, to provide the RFC5705 context, the  <code>contect</code> variable
must be non-null.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p>
<p><strong>Since:</strong> 3.4.4
</p></dd></dl>

<a name="gnutls_005fpriority_005fcertificate_005ftype_005flist-1"></a>
<h4 class="subheading">gnutls_priority_certificate_type_list</h4>
<a name="gnutls_005fpriority_005fcertificate_005ftype_005flist"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fcertificate_005ftype_005flist"></a>Function: <em>int</em> <strong>gnutls_priority_certificate_type_list</strong> <em>(gnutls_priority_t <var>pcache</var>, const unsigned int ** <var>list</var>)</em></dt>
<dd><p><var>pcache</var>: is a <code>gnutls_prioritity_t</code>  type.
</p>
<p><var>list</var>: will point to an integer list
</p>
<p>Get a list of available certificate types in the priority
structure. 
</p>
<p><strong>Returns:</strong> the number of certificate types, or an error code.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpriority_005fcipher_005flist-1"></a>
<h4 class="subheading">gnutls_priority_cipher_list</h4>
<a name="gnutls_005fpriority_005fcipher_005flist"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fcipher_005flist"></a>Function: <em>int</em> <strong>gnutls_priority_cipher_list</strong> <em>(gnutls_priority_t <var>pcache</var>, const unsigned int ** <var>list</var>)</em></dt>
<dd><p><var>pcache</var>: is a <code>gnutls_prioritity_t</code>  type.
</p>
<p><var>list</var>: will point to an integer list
</p>
<p>Get a list of available ciphers in the priority
structure. 
</p>
<p><strong>Returns:</strong> the number of curves, or an error code.
</p>
<p><strong>Since:</strong> 3.2.3
</p></dd></dl>

<a name="gnutls_005fpriority_005fcompression_005flist-1"></a>
<h4 class="subheading">gnutls_priority_compression_list</h4>
<a name="gnutls_005fpriority_005fcompression_005flist"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fcompression_005flist"></a>Function: <em>int</em> <strong>gnutls_priority_compression_list</strong> <em>(gnutls_priority_t <var>pcache</var>, const unsigned int ** <var>list</var>)</em></dt>
<dd><p><var>pcache</var>: is a <code>gnutls_prioritity_t</code>  type.
</p>
<p><var>list</var>: will point to an integer list
</p>
<p>Get a list of available compression method in the priority
structure. 
</p>
<p><strong>Returns:</strong> the number of methods, or an error code.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpriority_005fdeinit-1"></a>
<h4 class="subheading">gnutls_priority_deinit</h4>
<a name="gnutls_005fpriority_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_priority_deinit</strong> <em>(gnutls_priority_t <var>priority_cache</var>)</em></dt>
<dd><p><var>priority_cache</var>: is a <code>gnutls_prioritity_t</code>  type.
</p>
<p>Deinitializes the priority cache.
</p></dd></dl>

<a name="gnutls_005fpriority_005fecc_005fcurve_005flist-1"></a>
<h4 class="subheading">gnutls_priority_ecc_curve_list</h4>
<a name="gnutls_005fpriority_005fecc_005fcurve_005flist"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fecc_005fcurve_005flist"></a>Function: <em>int</em> <strong>gnutls_priority_ecc_curve_list</strong> <em>(gnutls_priority_t <var>pcache</var>, const unsigned int ** <var>list</var>)</em></dt>
<dd><p><var>pcache</var>: is a <code>gnutls_prioritity_t</code>  type.
</p>
<p><var>list</var>: will point to an integer list
</p>
<p>Get a list of available elliptic curves in the priority
structure. 
</p>
<p><strong>Returns:</strong> the number of curves, or an error code.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpriority_005fget_005fcipher_005fsuite_005findex-1"></a>
<h4 class="subheading">gnutls_priority_get_cipher_suite_index</h4>
<a name="gnutls_005fpriority_005fget_005fcipher_005fsuite_005findex"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fget_005fcipher_005fsuite_005findex"></a>Function: <em>int</em> <strong>gnutls_priority_get_cipher_suite_index</strong> <em>(gnutls_priority_t <var>pcache</var>, unsigned int <var>idx</var>, unsigned int * <var>sidx</var>)</em></dt>
<dd><p><var>pcache</var>: is a <code>gnutls_prioritity_t</code>  type.
</p>
<p><var>idx</var>: is an index number.
</p>
<p><var>sidx</var>: internal index of cipher suite to get information about.
</p>
<p>Provides the internal ciphersuite index to be used with
<code>gnutls_cipher_suite_info()</code> . The index  <code>idx</code> provided is an 
index kept at the priorities structure. It might be that a valid
priorities index does not correspond to a ciphersuite and in 
that case <code>GNUTLS_E_UNKNOWN_CIPHER_SUITE</code>  will be returned. 
Once the last available index is crossed then 
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be returned.
</p>
<p><strong>Returns:</strong> On success it returns <code>GNUTLS_E_SUCCESS</code>  (0), or a negative error value otherwise.
</p>
<p><strong>Since:</strong> 3.0.9
</p></dd></dl>

<a name="gnutls_005fpriority_005finit-1"></a>
<h4 class="subheading">gnutls_priority_init</h4>
<a name="gnutls_005fpriority_005finit"></a><dl>
<dt><a name="index-gnutls_005fpriority_005finit"></a>Function: <em>int</em> <strong>gnutls_priority_init</strong> <em>(gnutls_priority_t * <var>priority_cache</var>, const char * <var>priorities</var>, const char ** <var>err_pos</var>)</em></dt>
<dd><p><var>priority_cache</var>: is a <code>gnutls_prioritity_t</code>  type.
</p>
<p><var>priorities</var>: is a string describing priorities (may be <code>NULL</code> )
</p>
<p><var>err_pos</var>: In case of an error this will have the position in the string the error occurred
</p>
<p>Sets priorities for the ciphers, key exchange methods, macs and
compression methods. The  <code>priority_cache</code> should be deinitialized
using <code>gnutls_priority_deinit()</code> .
</p>
<p>The <code>priorities</code>  option allows you to specify a colon
separated list of the cipher priorities to enable.
Some keywords are defined to provide quick access
to common preferences.
</p>
<p>Unless there is a special need, use the &quot;NORMAL&quot; keyword to
apply a reasonable security level, or &quot;NORMAL:<code>COMPAT</code> &quot; for compatibility.
</p>
<p>&quot;PERFORMANCE&quot; means all the &quot;secure&quot; ciphersuites are enabled,
limited to 128 bit ciphers and sorted by terms of speed
performance.
</p>
<p>&quot;LEGACY&quot; the NORMAL settings for GnuTLS 3.2.x or earlier. There is
no verification profile set, and the allowed DH primes are considered
weak today.
</p>
<p>&quot;NORMAL&quot; means all &quot;secure&quot; ciphersuites. The 256-bit ciphers are
included as a fallback only.  The ciphers are sorted by security
margin.
</p>
<p>&quot;PFS&quot; means all &quot;secure&quot; ciphersuites that support perfect forward secrecy. 
The 256-bit ciphers are included as a fallback only.  
The ciphers are sorted by security margin.
</p>
<p>&quot;SECURE128&quot; means all &quot;secure&quot; ciphersuites of security level 128-bit
or more.
</p>
<p>&quot;SECURE192&quot; means all &quot;secure&quot; ciphersuites of security level 192-bit
or more.
</p>
<p>&quot;SUITEB128&quot; means all the NSA SuiteB ciphersuites with security level
of 128.
</p>
<p>&quot;SUITEB192&quot; means all the NSA SuiteB ciphersuites with security level
of 192.
</p>
<p>&quot;NONE&quot; means nothing is enabled.  This disables even protocols and
compression methods.
</p>
<p>&quot; <code>KEYWORD</code> &quot; The system administrator imposed settings. The provided keywords
will be expanded from a configuration-time provided file - default is:
/etc/gnutls/default-priorities. Any keywords that follow it, will 
be appended to the expanded string. If there is no system string,
then the function will fail. The system file should be formatted
as &quot;KEYWORD=VALUE&quot;, e.g., &quot;SYSTEM=NORMAL:+ARCFOUR-128&quot;.
</p>
<p>Special keywords are &quot;!&quot;, &quot;-&quot; and &quot;+&quot;.
&quot;!&quot; or &quot;-&quot; appended with an algorithm will remove this algorithm.
&quot;+&quot; appended with an algorithm will add this algorithm.
</p>
<p>Check the GnuTLS manual section &quot;Priority strings&quot; for detailed
information.
</p>
<p><strong>Examples:</strong> 
&quot;NONE:+VERS-TLS-ALL:+MAC-ALL:+RSA:+AES-128-CBC:+SIGN-ALL:+COMP-NULL&quot;
</p>
<p>&quot;NORMAL:+ARCFOUR-128&quot; means normal ciphers plus ARCFOUR-128.
</p>
<p>&quot;SECURE128:-VERS-SSL3.0:+COMP-DEFLATE&quot; means that only secure ciphers are
enabled, SSL3.0 is disabled, and libz compression enabled.
</p>
<p>&quot;NONE:+VERS-TLS-ALL:+AES-128-CBC:+RSA:+SHA1:+COMP-NULL:+SIGN-RSA-SHA1&quot;, 
</p>
<p>&quot;NONE:+VERS-TLS-ALL:+AES-128-CBC:+ECDHE-RSA:+SHA1:+COMP-NULL:+SIGN-RSA-SHA1:+CURVE-SECP256R1&quot;, 
</p>
<p>&quot;SECURE256:+SECURE128&quot;,
</p>
<p>Note that &quot;NORMAL:<code>COMPAT</code> &quot; is the most compatible mode.
</p>
<p>A <code>NULL</code>   <code>priorities</code> string indicates the default priorities to be
used (this is available since GnuTLS 3.3.0).
</p>
<p><strong>Returns:</strong> On syntax error <code>GNUTLS_E_INVALID_REQUEST</code>  is returned,
<code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fpriority_005fkx_005flist-1"></a>
<h4 class="subheading">gnutls_priority_kx_list</h4>
<a name="gnutls_005fpriority_005fkx_005flist"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fkx_005flist"></a>Function: <em>int</em> <strong>gnutls_priority_kx_list</strong> <em>(gnutls_priority_t <var>pcache</var>, const unsigned int ** <var>list</var>)</em></dt>
<dd><p><var>pcache</var>: is a <code>gnutls_prioritity_t</code>  type.
</p>
<p><var>list</var>: will point to an integer list
</p>
<p>Get a list of available key exchange methods in the priority
structure. 
</p>
<p><strong>Returns:</strong> the number of curves, or an error code.
</p>
<p><strong>Since:</strong> 3.2.3
</p></dd></dl>

<a name="gnutls_005fpriority_005fmac_005flist-1"></a>
<h4 class="subheading">gnutls_priority_mac_list</h4>
<a name="gnutls_005fpriority_005fmac_005flist"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fmac_005flist"></a>Function: <em>int</em> <strong>gnutls_priority_mac_list</strong> <em>(gnutls_priority_t <var>pcache</var>, const unsigned int ** <var>list</var>)</em></dt>
<dd><p><var>pcache</var>: is a <code>gnutls_prioritity_t</code>  type.
</p>
<p><var>list</var>: will point to an integer list
</p>
<p>Get a list of available MAC algorithms in the priority
structure. 
</p>
<p><strong>Returns:</strong> the number of curves, or an error code.
</p>
<p><strong>Since:</strong> 3.2.3
</p></dd></dl>

<a name="gnutls_005fpriority_005fprotocol_005flist-1"></a>
<h4 class="subheading">gnutls_priority_protocol_list</h4>
<a name="gnutls_005fpriority_005fprotocol_005flist"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fprotocol_005flist"></a>Function: <em>int</em> <strong>gnutls_priority_protocol_list</strong> <em>(gnutls_priority_t <var>pcache</var>, const unsigned int ** <var>list</var>)</em></dt>
<dd><p><var>pcache</var>: is a <code>gnutls_prioritity_t</code>  type.
</p>
<p><var>list</var>: will point to an integer list
</p>
<p>Get a list of available TLS version numbers in the priority
structure. 
</p>
<p><strong>Returns:</strong> the number of protocols, or an error code.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpriority_005fset-1"></a>
<h4 class="subheading">gnutls_priority_set</h4>
<a name="gnutls_005fpriority_005fset"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fset"></a>Function: <em>int</em> <strong>gnutls_priority_set</strong> <em>(gnutls_session_t <var>session</var>, gnutls_priority_t <var>priority</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>priority</var>: is a <code>gnutls_priority_t</code>  type.
</p>
<p>Sets the priorities to use on the ciphers, key exchange methods,
macs and compression methods.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fpriority_005fset_005fdirect-1"></a>
<h4 class="subheading">gnutls_priority_set_direct</h4>
<a name="gnutls_005fpriority_005fset_005fdirect"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fset_005fdirect"></a>Function: <em>int</em> <strong>gnutls_priority_set_direct</strong> <em>(gnutls_session_t <var>session</var>, const char * <var>priorities</var>, const char ** <var>err_pos</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>priorities</var>: is a string describing priorities
</p>
<p><var>err_pos</var>: In case of an error this will have the position in the string the error occurred
</p>
<p>Sets the priorities to use on the ciphers, key exchange methods,
macs and compression methods.  This function avoids keeping a
priority cache and is used to directly set string priorities to a
TLS session.  For documentation check the <code>gnutls_priority_init()</code> .
</p>
<p>To simply use a reasonable default, consider using <code>gnutls_set_default_priority()</code> .
</p>
<p><strong>Returns:</strong> On syntax error <code>GNUTLS_E_INVALID_REQUEST</code>  is returned,
<code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fpriority_005fsign_005flist-1"></a>
<h4 class="subheading">gnutls_priority_sign_list</h4>
<a name="gnutls_005fpriority_005fsign_005flist"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fsign_005flist"></a>Function: <em>int</em> <strong>gnutls_priority_sign_list</strong> <em>(gnutls_priority_t <var>pcache</var>, const unsigned int ** <var>list</var>)</em></dt>
<dd><p><var>pcache</var>: is a <code>gnutls_prioritity_t</code>  type.
</p>
<p><var>list</var>: will point to an integer list
</p>
<p>Get a list of available signature algorithms in the priority
structure. 
</p>
<p><strong>Returns:</strong> the number of algorithms, or an error code.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpriority_005fstring_005flist-1"></a>
<h4 class="subheading">gnutls_priority_string_list</h4>
<a name="gnutls_005fpriority_005fstring_005flist"></a><dl>
<dt><a name="index-gnutls_005fpriority_005fstring_005flist"></a>Function: <em>const char *</em> <strong>gnutls_priority_string_list</strong> <em>(unsigned <var>iter</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>iter</var>: an integer counter starting from zero
</p>
<p><var>flags</var>: one of <code>GNUTLS_PRIORITY_LIST_INIT_KEYWORDS</code> , <code>GNUTLS_PRIORITY_LIST_SPECIAL</code> 
</p>
<p>Can be used to iterate all available priority strings.
Due to internal implementation details, there are cases where this
function can return the empty string. In that case that string should be ignored.
When no strings are available it returns <code>NULL</code> .
</p>
<p><strong>Returns:</strong> a priority string
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fprotocol_005fget_005fid-1"></a>
<h4 class="subheading">gnutls_protocol_get_id</h4>
<a name="gnutls_005fprotocol_005fget_005fid"></a><dl>
<dt><a name="index-gnutls_005fprotocol_005fget_005fid"></a>Function: <em>gnutls_protocol_t</em> <strong>gnutls_protocol_get_id</strong> <em>(const char * <var>name</var>)</em></dt>
<dd><p><var>name</var>: is a protocol name
</p>
<p>The names are compared in a case insensitive way.
</p>
<p><strong>Returns:</strong> an id of the specified protocol, or
<code>GNUTLS_VERSION_UNKNOWN</code>  on error.
</p></dd></dl>

<a name="gnutls_005fprotocol_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_protocol_get_name</h4>
<a name="gnutls_005fprotocol_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fprotocol_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_protocol_get_name</strong> <em>(gnutls_protocol_t <var>version</var>)</em></dt>
<dd><p><var>version</var>: is a (gnutls) version number
</p>
<p>Convert a <code>gnutls_protocol_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified TLS
version (e.g., &quot;TLS1.0&quot;), or <code>NULL</code> .
</p></dd></dl>

<a name="gnutls_005fprotocol_005fget_005fversion-1"></a>
<h4 class="subheading">gnutls_protocol_get_version</h4>
<a name="gnutls_005fprotocol_005fget_005fversion"></a><dl>
<dt><a name="index-gnutls_005fprotocol_005fget_005fversion"></a>Function: <em>gnutls_protocol_t</em> <strong>gnutls_protocol_get_version</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Get TLS version, a <code>gnutls_protocol_t</code>  value.
</p>
<p><strong>Returns:</strong> The version of the currently used protocol.
</p></dd></dl>

<a name="gnutls_005fprotocol_005flist-1"></a>
<h4 class="subheading">gnutls_protocol_list</h4>
<a name="gnutls_005fprotocol_005flist"></a><dl>
<dt><a name="index-gnutls_005fprotocol_005flist"></a>Function: <em>const gnutls_protocol_t *</em> <strong>gnutls_protocol_list</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>Get a list of supported protocols, e.g. SSL 3.0, TLS 1.0 etc.
</p>
<p>This function is not thread safe.
</p>
<p><strong>Returns:</strong> a (0)-terminated list of <code>gnutls_protocol_t</code>  integers
indicating the available protocols.
</p></dd></dl>

<a name="gnutls_005fpsk_005fallocate_005fclient_005fcredentials-1"></a>
<h4 class="subheading">gnutls_psk_allocate_client_credentials</h4>
<a name="gnutls_005fpsk_005fallocate_005fclient_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fpsk_005fallocate_005fclient_005fcredentials"></a>Function: <em>int</em> <strong>gnutls_psk_allocate_client_credentials</strong> <em>(gnutls_psk_client_credentials_t *            <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a pointer to a <code>gnutls_psk_server_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus this
helper function is provided in order to allocate it.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fpsk_005fallocate_005fserver_005fcredentials-1"></a>
<h4 class="subheading">gnutls_psk_allocate_server_credentials</h4>
<a name="gnutls_005fpsk_005fallocate_005fserver_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fpsk_005fallocate_005fserver_005fcredentials"></a>Function: <em>int</em> <strong>gnutls_psk_allocate_server_credentials</strong> <em>(gnutls_psk_server_credentials_t *            <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a pointer to a <code>gnutls_psk_server_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus this
helper function is provided in order to allocate it.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fpsk_005fclient_005fget_005fhint-1"></a>
<h4 class="subheading">gnutls_psk_client_get_hint</h4>
<a name="gnutls_005fpsk_005fclient_005fget_005fhint"></a><dl>
<dt><a name="index-gnutls_005fpsk_005fclient_005fget_005fhint"></a>Function: <em>const char *</em> <strong>gnutls_psk_client_get_hint</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p>The PSK identity hint may give the client help in deciding which
username to use.  This should only be called in case of PSK
authentication and in case of a client.
</p>
<p><strong>Returns:</strong> the identity hint of the peer, or <code>NULL</code>  in case of an error.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fpsk_005ffree_005fclient_005fcredentials-1"></a>
<h4 class="subheading">gnutls_psk_free_client_credentials</h4>
<a name="gnutls_005fpsk_005ffree_005fclient_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fpsk_005ffree_005fclient_005fcredentials"></a>Function: <em>void</em> <strong>gnutls_psk_free_client_credentials</strong> <em>(gnutls_psk_client_credentials_t <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_psk_client_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus this
helper function is provided in order to free (deallocate) it.
</p></dd></dl>

<a name="gnutls_005fpsk_005ffree_005fserver_005fcredentials-1"></a>
<h4 class="subheading">gnutls_psk_free_server_credentials</h4>
<a name="gnutls_005fpsk_005ffree_005fserver_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fpsk_005ffree_005fserver_005fcredentials"></a>Function: <em>void</em> <strong>gnutls_psk_free_server_credentials</strong> <em>(gnutls_psk_server_credentials_t <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_psk_server_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus this
helper function is provided in order to free (deallocate) it.
</p></dd></dl>

<a name="gnutls_005fpsk_005fserver_005fget_005fusername-1"></a>
<h4 class="subheading">gnutls_psk_server_get_username</h4>
<a name="gnutls_005fpsk_005fserver_005fget_005fusername"></a><dl>
<dt><a name="index-gnutls_005fpsk_005fserver_005fget_005fusername"></a>Function: <em>const char *</em> <strong>gnutls_psk_server_get_username</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p>This should only be called in case of PSK authentication and in
case of a server.
</p>
<p><strong>Returns:</strong> the username of the peer, or <code>NULL</code>  in case of an error.
</p></dd></dl>

<a name="gnutls_005fpsk_005fset_005fclient_005fcredentials-1"></a>
<h4 class="subheading">gnutls_psk_set_client_credentials</h4>
<a name="gnutls_005fpsk_005fset_005fclient_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fpsk_005fset_005fclient_005fcredentials"></a>Function: <em>int</em> <strong>gnutls_psk_set_client_credentials</strong> <em>(gnutls_psk_client_credentials_t <var>res</var>, const char * <var>username</var>, const gnutls_datum_t * <var>key</var>, gnutls_psk_key_flags <var>flags</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_psk_client_credentials_t</code>  type.
</p>
<p><var>username</var>: is the user&rsquo;s zero-terminated userid
</p>
<p><var>key</var>: is the user&rsquo;s key
</p>
<p><var>flags</var>: indicate the format of the key, either
<code>GNUTLS_PSK_KEY_RAW</code>  or <code>GNUTLS_PSK_KEY_HEX</code> .
</p>
<p>This function sets the username and password, in a
gnutls_psk_client_credentials_t type.  Those will be used in
PSK authentication.   <code>username</code> should be an ASCII string or UTF-8
strings prepared using the &quot;SASLprep&quot; profile of &quot;stringprep&quot;.  The
key can be either in raw byte format or in Hex format (without the
0x prefix).
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fpsk_005fset_005fclient_005fcredentials_005ffunction-1"></a>
<h4 class="subheading">gnutls_psk_set_client_credentials_function</h4>
<a name="gnutls_005fpsk_005fset_005fclient_005fcredentials_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fpsk_005fset_005fclient_005fcredentials_005ffunction-1"></a>Function: <em>void</em> <strong>gnutls_psk_set_client_credentials_function</strong> <em>(gnutls_psk_client_credentials_t         <var>cred</var>, gnutls_psk_client_credentials_function         * <var>func</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_psk_server_credentials_t</code>  type.
</p>
<p><var>func</var>: is the callback function
</p>
<p>This function can be used to set a callback to retrieve the username and
password for client PSK authentication.
The callback&rsquo;s function form is:
int (*callback)(gnutls_session_t, char** username,
gnutls_datum_t* key);
</p>
<p>The  <code>username</code> and  <code>key</code> -&gt;data must be allocated using <code>gnutls_malloc()</code> .
 <code>username</code> should be ASCII strings or UTF-8 strings prepared using
the &quot;SASLprep&quot; profile of &quot;stringprep&quot;.
</p>
<p>The callback function will be called once per handshake.
</p>
<p>The callback function should return 0 on success.
-1 indicates an error.
</p></dd></dl>

<a name="gnutls_005fpsk_005fset_005fparams_005ffunction-1"></a>
<h4 class="subheading">gnutls_psk_set_params_function</h4>
<a name="gnutls_005fpsk_005fset_005fparams_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fpsk_005fset_005fparams_005ffunction"></a>Function: <em>void</em> <strong>gnutls_psk_set_params_function</strong> <em>(gnutls_psk_server_credentials_t <var>res</var>, gnutls_params_function * <var>func</var>)</em></dt>
<dd><p><var>res</var>: is a gnutls_psk_server_credentials_t type
</p>
<p><var>func</var>: is the function to be called
</p>
<p>This function will set a callback in order for the server to get
the Diffie-Hellman or RSA parameters for PSK authentication.  The
callback should return <code>GNUTLS_E_SUCCESS</code>  (0) on success.
</p></dd></dl>

<a name="gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffile-1"></a>
<h4 class="subheading">gnutls_psk_set_server_credentials_file</h4>
<a name="gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffile"></a><dl>
<dt><a name="index-gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffile-1"></a>Function: <em>int</em> <strong>gnutls_psk_set_server_credentials_file</strong> <em>(gnutls_psk_server_credentials_t            <var>res</var>, const char * <var>password_file</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_psk_server_credentials_t</code>  type.
</p>
<p><var>password_file</var>: is the PSK password file (passwd.psk)
</p>
<p>This function sets the password file, in a
<code>gnutls_psk_server_credentials_t</code>  type.  This password file
holds usernames and keys and will be used for PSK authentication.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffunction-1"></a>
<h4 class="subheading">gnutls_psk_set_server_credentials_function</h4>
<a name="gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffunction"></a>Function: <em>void</em> <strong>gnutls_psk_set_server_credentials_function</strong> <em>(gnutls_psk_server_credentials_t         <var>cred</var>, gnutls_psk_server_credentials_function         * <var>func</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_psk_server_credentials_t</code>  type.
</p>
<p><var>func</var>: is the callback function
</p>
<p>This function can be used to set a callback to retrieve the user&rsquo;s PSK credentials.
The callback&rsquo;s function form is:
int (*callback)(gnutls_session_t, const char* username,
gnutls_datum_t* key);
</p>
<p><code>username</code> contains the actual username.
The  <code>key</code> must be filled in using the <code>gnutls_malloc()</code> .
</p>
<p>In case the callback returned a negative number then gnutls will
assume that the username does not exist.
</p>
<p>The callback function will only be called once per handshake.  The
callback function should return 0 on success, while -1 indicates
an error.
</p></dd></dl>

<a name="gnutls_005fpsk_005fset_005fserver_005fcredentials_005fhint-1"></a>
<h4 class="subheading">gnutls_psk_set_server_credentials_hint</h4>
<a name="gnutls_005fpsk_005fset_005fserver_005fcredentials_005fhint"></a><dl>
<dt><a name="index-gnutls_005fpsk_005fset_005fserver_005fcredentials_005fhint"></a>Function: <em>int</em> <strong>gnutls_psk_set_server_credentials_hint</strong> <em>(gnutls_psk_server_credentials_t <var>res</var>, const char * <var>hint</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_psk_server_credentials_t</code>  type.
</p>
<p><var>hint</var>: is the PSK identity hint string
</p>
<p>This function sets the identity hint, in a
<code>gnutls_psk_server_credentials_t</code>  type.  This hint is sent to
the client to help it chose a good PSK credential (i.e., username
and password).
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fpsk_005fset_005fserver_005fdh_005fparams-1"></a>
<h4 class="subheading">gnutls_psk_set_server_dh_params</h4>
<a name="gnutls_005fpsk_005fset_005fserver_005fdh_005fparams"></a><dl>
<dt><a name="index-gnutls_005fpsk_005fset_005fserver_005fdh_005fparams"></a>Function: <em>void</em> <strong>gnutls_psk_set_server_dh_params</strong> <em>(gnutls_psk_server_credentials_t <var>res</var>, gnutls_dh_params_t <var>dh_params</var>)</em></dt>
<dd><p><var>res</var>: is a gnutls_psk_server_credentials_t type
</p>
<p><var>dh_params</var>: is a structure that holds Diffie-Hellman parameters.
</p>
<p>This function will set the Diffie-Hellman parameters for an
anonymous server to use. These parameters will be used in
Diffie-Hellman exchange with PSK cipher suites.
</p></dd></dl>

<a name="gnutls_005fpsk_005fset_005fserver_005fparams_005ffunction-1"></a>
<h4 class="subheading">gnutls_psk_set_server_params_function</h4>
<a name="gnutls_005fpsk_005fset_005fserver_005fparams_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fpsk_005fset_005fserver_005fparams_005ffunction"></a>Function: <em>void</em> <strong>gnutls_psk_set_server_params_function</strong> <em>(gnutls_psk_server_credentials_t <var>res</var>, gnutls_params_function * <var>func</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type
</p>
<p><var>func</var>: is the function to be called
</p>
<p>This function will set a callback in order for the server to get
the Diffie-Hellman parameters for PSK authentication.  The callback
should return <code>GNUTLS_E_SUCCESS</code>  (0) on success.
</p></dd></dl>

<a name="gnutls_005frandom_005fart-1"></a>
<h4 class="subheading">gnutls_random_art</h4>
<a name="gnutls_005frandom_005fart"></a><dl>
<dt><a name="index-gnutls_005frandom_005fart"></a>Function: <em>int</em> <strong>gnutls_random_art</strong> <em>(gnutls_random_art_t <var>type</var>, const char * <var>key_type</var>, unsigned int <var>key_size</var>, void * <var>fpr</var>, size_t <var>fpr_size</var>, gnutls_datum_t * <var>art</var>)</em></dt>
<dd><p><var>type</var>: The type of the random art (for now only <code>GNUTLS_RANDOM_ART_OPENSSH</code>  is supported)
</p>
<p><var>key_type</var>: The type of the key (RSA, DSA etc.)
</p>
<p><var>key_size</var>: The size of the key in bits
</p>
<p><var>fpr</var>: The fingerprint of the key
</p>
<p><var>fpr_size</var>: The size of the fingerprint
</p>
<p><var>art</var>: The returned random art
</p>
<p>This function will convert a given fingerprint to an &quot;artistic&quot;
image. The returned image is allocated using <code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005frange_005fsplit-1"></a>
<h4 class="subheading">gnutls_range_split</h4>
<a name="gnutls_005frange_005fsplit"></a><dl>
<dt><a name="index-gnutls_005frange_005fsplit"></a>Function: <em>int</em> <strong>gnutls_range_split</strong> <em>(gnutls_session_t <var>session</var>, const gnutls_range_st * <var>orig</var>, gnutls_range_st * <var>next</var>, gnutls_range_st * <var>remainder</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type
</p>
<p><var>orig</var>: is the original range provided by the user
</p>
<p><var>next</var>: is the returned range that can be conveyed in a TLS record
</p>
<p><var>remainder</var>: is the returned remaining range
</p>
<p>This function should be used when it is required to hide the length
of very long data that cannot be directly provided to <code>gnutls_record_send_range()</code> .
In that case this function should be called with the desired length
hiding range in  <code>orig</code> . The returned  <code>next</code> value should then be used in
the next call to <code>gnutls_record_send_range()</code>  with the partial data.
That process should be repeated until  <code>remainder</code> is (0,0).
</p>
<p><strong>Returns:</strong> 0 in case splitting succeeds, non zero in case of error.
Note that  <code>orig</code> is not changed, while the values of  <code>next</code> and  <code>remainder</code> are modified to store the resulting values.
</p></dd></dl>

<a name="gnutls_005frecord_005fcan_005fuse_005flength_005fhiding-1"></a>
<h4 class="subheading">gnutls_record_can_use_length_hiding</h4>
<a name="gnutls_005frecord_005fcan_005fuse_005flength_005fhiding"></a><dl>
<dt><a name="index-gnutls_005frecord_005fcan_005fuse_005flength_005fhiding"></a>Function: <em>int</em> <strong>gnutls_record_can_use_length_hiding</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>If the session supports length-hiding padding, you can
invoke <code>gnutls_range_send_message()</code>  to send a message whose
length is hidden in the given range. If the session does not
support length hiding padding, you can use the standard
<code>gnutls_record_send()</code>  function, or <code>gnutls_range_send_message()</code> 
making sure that the range is the same as the length of the
message you are trying to send.
</p>
<p><strong>Returns:</strong> true (1) if the current session supports length-hiding
padding, false (0) if the current session does not.
</p></dd></dl>

<a name="gnutls_005frecord_005fcheck_005fcorked-1"></a>
<h4 class="subheading">gnutls_record_check_corked</h4>
<a name="gnutls_005frecord_005fcheck_005fcorked"></a><dl>
<dt><a name="index-gnutls_005frecord_005fcheck_005fcorked"></a>Function: <em>size_t</em> <strong>gnutls_record_check_corked</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function checks if there pending corked
data in the gnutls buffers &ndash;see <code>gnutls_record_cork()</code> . 
</p>
<p><strong>Returns:</strong> Returns the size of the corked data or zero.
</p>
<p><strong>Since:</strong> 3.2.8
</p></dd></dl>

<a name="gnutls_005frecord_005fcheck_005fpending-1"></a>
<h4 class="subheading">gnutls_record_check_pending</h4>
<a name="gnutls_005frecord_005fcheck_005fpending"></a><dl>
<dt><a name="index-gnutls_005frecord_005fcheck_005fpending-1"></a>Function: <em>size_t</em> <strong>gnutls_record_check_pending</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function checks if there are unread data
in the gnutls buffers. If the return value is
non-zero the next call to <code>gnutls_record_recv()</code> 
is guaranteed not to block.
</p>
<p><strong>Returns:</strong> Returns the size of the data or zero.
</p></dd></dl>

<a name="gnutls_005frecord_005fcork-1"></a>
<h4 class="subheading">gnutls_record_cork</h4>
<a name="gnutls_005frecord_005fcork"></a><dl>
<dt><a name="index-gnutls_005frecord_005fcork-1"></a>Function: <em>void</em> <strong>gnutls_record_cork</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>If called, <code>gnutls_record_send()</code>  will no longer send any records.
Any sent records will be cached until <code>gnutls_record_uncork()</code>  is called.
</p>
<p>This function is safe to use with DTLS after GnuTLS 3.3.0.
</p>
<p><strong>Since:</strong> 3.1.9
</p></dd></dl>

<a name="gnutls_005frecord_005fdisable_005fpadding-1"></a>
<h4 class="subheading">gnutls_record_disable_padding</h4>
<a name="gnutls_005frecord_005fdisable_005fpadding"></a><dl>
<dt><a name="index-gnutls_005frecord_005fdisable_005fpadding"></a>Function: <em>void</em> <strong>gnutls_record_disable_padding</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Used to disabled padding in TLS 1.0 and above.  Normally you do not
need to use this function, but there are buggy clients that
complain if a server pads the encrypted data.  This of course will
disable protection against statistical attacks on the data.
</p>
<p>This functions is defunt since 3.1.7. Random padding is disabled
by default unless requested using <code>gnutls_range_send_message()</code> .
</p></dd></dl>

<a name="gnutls_005frecord_005fdiscard_005fqueued-1"></a>
<h4 class="subheading">gnutls_record_discard_queued</h4>
<a name="gnutls_005frecord_005fdiscard_005fqueued"></a><dl>
<dt><a name="index-gnutls_005frecord_005fdiscard_005fqueued"></a>Function: <em>size_t</em> <strong>gnutls_record_discard_queued</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function discards all queued to be sent packets in a TLS or DTLS session.
These are the packets queued after an interrupted <code>gnutls_record_send()</code> .
</p>
<p><strong>Returns:</strong> The number of bytes discarded.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005frecord_005fget_005fdirection-1"></a>
<h4 class="subheading">gnutls_record_get_direction</h4>
<a name="gnutls_005frecord_005fget_005fdirection"></a><dl>
<dt><a name="index-gnutls_005frecord_005fget_005fdirection-1"></a>Function: <em>int</em> <strong>gnutls_record_get_direction</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function provides information about the internals of the
record protocol and is only useful if a prior gnutls function call
(e.g.  <code>gnutls_handshake()</code> ) was interrupted for some reason, that
is, if a function returned <code>GNUTLS_E_INTERRUPTED</code>  or
<code>GNUTLS_E_AGAIN</code> .  In such a case, you might want to call <code>select()</code> 
or <code>poll()</code>  before calling the interrupted gnutls function again.  To
tell you whether a file descriptor should be selected for either
reading or writing, <code>gnutls_record_get_direction()</code>  returns 0 if the
interrupted function was trying to read data, and 1 if it was
trying to write data.
</p>
<p>This function&rsquo;s output is unreliable if you are using the
 <code>session</code> in different threads, for sending and receiving.
</p>
<p><strong>Returns:</strong> 0 if trying to read data, 1 if trying to write data.
</p></dd></dl>

<a name="gnutls_005frecord_005fget_005fmax_005fsize-1"></a>
<h4 class="subheading">gnutls_record_get_max_size</h4>
<a name="gnutls_005frecord_005fget_005fmax_005fsize"></a><dl>
<dt><a name="index-gnutls_005frecord_005fget_005fmax_005fsize"></a>Function: <em>size_t</em> <strong>gnutls_record_get_max_size</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Get the record size.  The maximum record size is negotiated by the
client after the first handshake message.
</p>
<p><strong>Returns:</strong> The maximum record packet size in this connection.
</p></dd></dl>

<a name="gnutls_005frecord_005fget_005fstate-1"></a>
<h4 class="subheading">gnutls_record_get_state</h4>
<a name="gnutls_005frecord_005fget_005fstate"></a><dl>
<dt><a name="index-gnutls_005frecord_005fget_005fstate"></a>Function: <em>int</em> <strong>gnutls_record_get_state</strong> <em>(gnutls_session_t <var>session</var>, unsigned <var>read</var>, gnutls_datum_t * <var>mac_key</var>, gnutls_datum_t * <var>IV</var>, gnutls_datum_t * <var>cipher_key</var>, unsigned char <var>seq_number[8]</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type
</p>
<p><var>read</var>: if non-zero the read parameters are returned, otherwise the write
</p>
<p><var>mac_key</var>: the key used for MAC (if a MAC is used)
</p>
<p><var>IV</var>: the initialization vector or nonce used
</p>
<p><var>cipher_key</var>: the cipher key
</p>
<p><var>seq_number[8]</var>: &ndash; undescribed &ndash;
</p>
<p>This function will return the parameters of the current record state.
These are only useful to be provided to an external off-loading device
or subsystem.
</p>
<p>In that case, to sync the state you must call <code>gnutls_record_set_state()</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p>
<p>Since 3.4.0
</p></dd></dl>

<a name="gnutls_005frecord_005foverhead_005fsize-1"></a>
<h4 class="subheading">gnutls_record_overhead_size</h4>
<a name="gnutls_005frecord_005foverhead_005fsize"></a><dl>
<dt><a name="index-gnutls_005frecord_005foverhead_005fsize"></a>Function: <em>size_t</em> <strong>gnutls_record_overhead_size</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is <code>gnutls_session_t</code> 
</p>
<p>This function will return the set size in bytes of the overhead
due to TLS (or DTLS) per record.
</p>
<p><strong>Since:</strong> 3.2.2
</p></dd></dl>

<a name="gnutls_005frecord_005frecv-1"></a>
<h4 class="subheading">gnutls_record_recv</h4>
<a name="gnutls_005frecord_005frecv"></a><dl>
<dt><a name="index-gnutls_005frecord_005frecv-1"></a>Function: <em>ssize_t</em> <strong>gnutls_record_recv</strong> <em>(gnutls_session_t <var>session</var>, void * <var>data</var>, size_t <var>data_size</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>data</var>: the buffer that the data will be read into
</p>
<p><var>data_size</var>: the number of requested bytes
</p>
<p>This function has the similar semantics with <code>recv()</code> .  The only
difference is that it accepts a GnuTLS session, and uses different
error codes.
In the special case that the peer requests a renegotiation, the
caller will receive an error code of <code>GNUTLS_E_REHANDSHAKE</code> .  In case
of a client, this message may be simply ignored, replied with an alert
<code>GNUTLS_A_NO_RENEGOTIATION</code> , or replied with a new handshake,
depending on the client&rsquo;s will. A server receiving this error code
can only initiate a new handshake or terminate the session.
</p>
<p>If <code>EINTR</code>  is returned by the internal push function (the default
is <code>recv()</code> ) then <code>GNUTLS_E_INTERRUPTED</code>  will be returned.  If
<code>GNUTLS_E_INTERRUPTED</code>  or <code>GNUTLS_E_AGAIN</code>  is returned, you must
call this function again to get the data.  See also
<code>gnutls_record_get_direction()</code> .
</p>
<p><strong>Returns:</strong> The number of bytes received and zero on EOF (for stream
connections).  A negative error code is returned in case of an error.  
The number of bytes received might be less than the requested  <code>data_size</code> .
</p></dd></dl>

<a name="gnutls_005frecord_005frecv_005fpacket-1"></a>
<h4 class="subheading">gnutls_record_recv_packet</h4>
<a name="gnutls_005frecord_005frecv_005fpacket"></a><dl>
<dt><a name="index-gnutls_005frecord_005frecv_005fpacket"></a>Function: <em>ssize_t</em> <strong>gnutls_record_recv_packet</strong> <em>(gnutls_session_t <var>session</var>, gnutls_packet_t * <var>packet</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>packet</var>: the structure that will hold the packet data
</p>
<p>This is a lower-level function than <code>gnutls_record_recv()</code>  and allows
to directly receive the whole decrypted packet. That avoids a
memory copy, and is intended to be used by applications seeking high
performance.
</p>
<p>The received packet is accessed using <code>gnutls_packet_get()</code>  and 
must be deinitialized using <code>gnutls_packet_deinit()</code> . The returned
packet will be <code>NULL</code>  if the return value is zero (EOF).
</p>
<p><strong>Returns:</strong> The number of bytes received and zero on EOF (for stream
connections).  A negative error code is returned in case of an error.  
</p>
<p><strong>Since:</strong> 3.3.5
</p></dd></dl>

<a name="gnutls_005frecord_005frecv_005fseq-1"></a>
<h4 class="subheading">gnutls_record_recv_seq</h4>
<a name="gnutls_005frecord_005frecv_005fseq"></a><dl>
<dt><a name="index-gnutls_005frecord_005frecv_005fseq-1"></a>Function: <em>ssize_t</em> <strong>gnutls_record_recv_seq</strong> <em>(gnutls_session_t <var>session</var>, void * <var>data</var>, size_t <var>data_size</var>, unsigned char * <var>seq</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>data</var>: the buffer that the data will be read into
</p>
<p><var>data_size</var>: the number of requested bytes
</p>
<p><var>seq</var>: is the packet&rsquo;s 64-bit sequence number. Should have space for 8 bytes.
</p>
<p>This function is the same as <code>gnutls_record_recv()</code> , except that
it returns in addition to data, the sequence number of the data.
This is useful in DTLS where record packets might be received
out-of-order. The returned 8-byte sequence number is an
integer in big-endian format and should be
treated as a unique message identification. 
</p>
<p><strong>Returns:</strong> The number of bytes received and zero on EOF.  A negative
error code is returned in case of an error.  The number of bytes
received might be less than  <code>data_size</code> .
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005frecord_005fsend-1"></a>
<h4 class="subheading">gnutls_record_send</h4>
<a name="gnutls_005frecord_005fsend"></a><dl>
<dt><a name="index-gnutls_005frecord_005fsend-1"></a>Function: <em>ssize_t</em> <strong>gnutls_record_send</strong> <em>(gnutls_session_t <var>session</var>, const void * <var>data</var>, size_t <var>data_size</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>data</var>: contains the data to send
</p>
<p><var>data_size</var>: is the length of the data
</p>
<p>This function has the similar semantics with <code>send()</code> .  The only
difference is that it accepts a GnuTLS session, and uses different
error codes.
Note that if the send buffer is full, <code>send()</code>  will block this
function.  See the <code>send()</code>  documentation for more information.  
</p>
<p>You can replace the default push function which is <code>send()</code> , by using
<code>gnutls_transport_set_push_function()</code> .
</p>
<p>If the EINTR is returned by the internal push function 
then <code>GNUTLS_E_INTERRUPTED</code>  will be returned. If
<code>GNUTLS_E_INTERRUPTED</code>  or <code>GNUTLS_E_AGAIN</code>  is returned, you must
call this function again, with the exact same parameters; alternatively
you could provide a <code>NULL</code>  pointer for data, and 0 for
size. cf. <code>gnutls_record_get_direction()</code> . 
</p>
<p>Note that in DTLS this function will return the <code>GNUTLS_E_LARGE_PACKET</code> 
error code if the send data exceed the data MTU value - as returned
by <code>gnutls_dtls_get_data_mtu()</code> . The errno value EMSGSIZE
also maps to <code>GNUTLS_E_LARGE_PACKET</code> . 
Note that since 3.2.13 this function can be called under cork in DTLS
mode, and will refuse to send data over the MTU size by returning
<code>GNUTLS_E_LARGE_PACKET</code> .
</p>
<p><strong>Returns:</strong> The number of bytes sent, or a negative error code.  The
number of bytes sent might be less than  <code>data_size</code> .  The maximum
number of bytes this function can send in a single call depends
on the negotiated maximum record size.
</p></dd></dl>

<a name="gnutls_005frecord_005fsend_005frange-1"></a>
<h4 class="subheading">gnutls_record_send_range</h4>
<a name="gnutls_005frecord_005fsend_005frange"></a><dl>
<dt><a name="index-gnutls_005frecord_005fsend_005frange"></a>Function: <em>ssize_t</em> <strong>gnutls_record_send_range</strong> <em>(gnutls_session_t <var>session</var>, const void * <var>data</var>, size_t <var>data_size</var>, const gnutls_range_st * <var>range</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>data</var>: contains the data to send.
</p>
<p><var>data_size</var>: is the length of the data.
</p>
<p><var>range</var>: is the range of lengths in which the real data length must be hidden.
</p>
<p>This function operates like <code>gnutls_record_send()</code>  but, while
<code>gnutls_record_send()</code>  adds minimal padding to each TLS record,
this function uses the TLS extra-padding feature to conceal the real
data size within the range of lengths provided.
Some TLS sessions do not support extra padding (e.g. stream ciphers in standard
TLS or SSL3 sessions). To know whether the current session supports extra
padding, and hence length hiding, use the <code>gnutls_record_can_use_length_hiding()</code> 
function.
</p>
<p><strong>Note:</strong> This function currently is only limited to blocking sockets.
</p>
<p><strong>Returns:</strong> The number of bytes sent (that is data_size in a successful invocation),
or a negative error code.
</p></dd></dl>

<a name="gnutls_005frecord_005fset_005fmax_005fsize-1"></a>
<h4 class="subheading">gnutls_record_set_max_size</h4>
<a name="gnutls_005frecord_005fset_005fmax_005fsize"></a><dl>
<dt><a name="index-gnutls_005frecord_005fset_005fmax_005fsize"></a>Function: <em>ssize_t</em> <strong>gnutls_record_set_max_size</strong> <em>(gnutls_session_t <var>session</var>, size_t <var>size</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>size</var>: is the new size
</p>
<p>This function sets the maximum record packet size in this
connection.  This property can only be set to clients.  The server
may choose not to accept the requested size.
</p>
<p>Acceptable values are 512(=2^9), 1024(=2^10), 2048(=2^11) and
4096(=2^12).  The requested record size does get in effect
immediately only while sending data. The receive part will take
effect after a successful handshake.
</p>
<p>This function uses a TLS extension called &rsquo;max record size&rsquo;.  Not
all TLS implementations use or even understand this extension.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005frecord_005fset_005fstate-1"></a>
<h4 class="subheading">gnutls_record_set_state</h4>
<a name="gnutls_005frecord_005fset_005fstate"></a><dl>
<dt><a name="index-gnutls_005frecord_005fset_005fstate"></a>Function: <em>int</em> <strong>gnutls_record_set_state</strong> <em>(gnutls_session_t <var>session</var>, unsigned <var>read</var>, unsigned char <var>seq_number[8]</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type
</p>
<p><var>read</var>: if non-zero the read parameters are returned, otherwise the write
</p>
<p><var>seq_number[8]</var>: &ndash; undescribed &ndash;
</p>
<p>This function will set the sequence number in the current record state.
This function is useful if sending and receiving are offloaded from
gnutls. That is, if <code>gnutls_record_get_state()</code>  was used.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p>
<p>Since 3.4.0
</p></dd></dl>

<a name="gnutls_005frecord_005fset_005ftimeout-1"></a>
<h4 class="subheading">gnutls_record_set_timeout</h4>
<a name="gnutls_005frecord_005fset_005ftimeout"></a><dl>
<dt><a name="index-gnutls_005frecord_005fset_005ftimeout"></a>Function: <em>void</em> <strong>gnutls_record_set_timeout</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>ms</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>ms</var>: is a timeout value in milliseconds
</p>
<p>This function sets the receive timeout for the record layer
to the provided value. Use an  <code>ms</code> value of zero to disable
timeout (the default).
</p>
<p>This function requires to set a pull timeout callback. See
<code>gnutls_transport_set_pull_timeout_function()</code> .
</p>
<p><strong>Since:</strong> 3.1.7
</p></dd></dl>

<a name="gnutls_005frecord_005funcork-1"></a>
<h4 class="subheading">gnutls_record_uncork</h4>
<a name="gnutls_005frecord_005funcork"></a><dl>
<dt><a name="index-gnutls_005frecord_005funcork-1"></a>Function: <em>int</em> <strong>gnutls_record_uncork</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>flags</var>: Could be zero or <code>GNUTLS_RECORD_WAIT</code> 
</p>
<p>This resets the effect of <code>gnutls_record_cork()</code> , and flushes any pending
data. If the <code>GNUTLS_RECORD_WAIT</code>  flag is specified then this
function will block until the data is sent or a fatal error
occurs (i.e., the function will retry on <code>GNUTLS_E_AGAIN</code>  and
<code>GNUTLS_E_INTERRUPTED</code> ).
</p>
<p>If the flag <code>GNUTLS_RECORD_WAIT</code>  is not specified and the function
is interrupted then the <code>GNUTLS_E_AGAIN</code>  or <code>GNUTLS_E_INTERRUPTED</code> 
errors will be returned. To obtain the data left in the corked
buffer use <code>gnutls_record_check_corked()</code> .
</p>
<p><strong>Returns:</strong> On success the number of transmitted data is returned, or 
otherwise a negative error code. 
</p>
<p><strong>Since:</strong> 3.1.9
</p></dd></dl>

<a name="gnutls_005frehandshake-1"></a>
<h4 class="subheading">gnutls_rehandshake</h4>
<a name="gnutls_005frehandshake"></a><dl>
<dt><a name="index-gnutls_005frehandshake-1"></a>Function: <em>int</em> <strong>gnutls_rehandshake</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function will renegotiate security parameters with the
client.  This should only be called in case of a server.
</p>
<p>This message informs the peer that we want to renegotiate
parameters (perform a handshake).
</p>
<p>If this function succeeds (returns 0), you must call the
<code>gnutls_handshake()</code>  function in order to negotiate the new
parameters.
</p>
<p>Since TLS is full duplex some application data might have been
sent during peer&rsquo;s processing of this message. In that case
one should call <code>gnutls_record_recv()</code>  until GNUTLS_E_REHANDSHAKE
is returned to clear any pending data. Care must be taken, if
rehandshake is mandatory, to terminate if it does not start after
some threshold.
</p>
<p>If the client does not wish to renegotiate parameters he 
should reply with an alert message, thus the return code will be
<code>GNUTLS_E_WARNING_ALERT_RECEIVED</code>  and the alert will be
<code>GNUTLS_A_NO_RENEGOTIATION</code> .  A client may also choose to ignore
this message.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p></dd></dl>

<a name="gnutls_005fsafe_005frenegotiation_005fstatus-1"></a>
<h4 class="subheading">gnutls_safe_renegotiation_status</h4>
<a name="gnutls_005fsafe_005frenegotiation_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fsafe_005frenegotiation_005fstatus-1"></a>Function: <em>int</em> <strong>gnutls_safe_renegotiation_status</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Can be used to check whether safe renegotiation is being used
in the current session.
</p>
<p><strong>Returns:</strong> 0 when safe renegotiation is not used and non (0) when
safe renegotiation is used.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fsec_005fparam_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_sec_param_get_name</h4>
<a name="gnutls_005fsec_005fparam_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fsec_005fparam_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_sec_param_get_name</strong> <em>(gnutls_sec_param_t <var>param</var>)</em></dt>
<dd><p><var>param</var>: is a security parameter
</p>
<p>Convert a <code>gnutls_sec_param_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a pointer to a string that contains the name of the
specified security level, or <code>NULL</code> .
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fsec_005fparam_005fto_005fpk_005fbits-1"></a>
<h4 class="subheading">gnutls_sec_param_to_pk_bits</h4>
<a name="gnutls_005fsec_005fparam_005fto_005fpk_005fbits"></a><dl>
<dt><a name="index-gnutls_005fsec_005fparam_005fto_005fpk_005fbits-1"></a>Function: <em>unsigned int</em> <strong>gnutls_sec_param_to_pk_bits</strong> <em>(gnutls_pk_algorithm_t <var>algo</var>, gnutls_sec_param_t <var>param</var>)</em></dt>
<dd><p><var>algo</var>: is a public key algorithm
</p>
<p><var>param</var>: is a security parameter
</p>
<p>When generating private and public key pairs a difficult question
is which size of &quot;bits&quot; the modulus will be in RSA and the group size
in DSA. The easy answer is 1024, which is also wrong. This function
will convert a human understandable security parameter to an
appropriate size for the specific algorithm.
</p>
<p><strong>Returns:</strong> The number of bits, or (0).
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fsec_005fparam_005fto_005fsymmetric_005fbits-1"></a>
<h4 class="subheading">gnutls_sec_param_to_symmetric_bits</h4>
<a name="gnutls_005fsec_005fparam_005fto_005fsymmetric_005fbits"></a><dl>
<dt><a name="index-gnutls_005fsec_005fparam_005fto_005fsymmetric_005fbits"></a>Function: <em>unsigned int</em> <strong>gnutls_sec_param_to_symmetric_bits</strong> <em>(gnutls_sec_param_t <var>param</var>)</em></dt>
<dd><p><var>param</var>: is a security parameter
</p>
<p>This function will return the number of bits that correspond to
symmetric cipher strength for the given security parameter.
</p>
<p><strong>Returns:</strong> The number of bits, or (0).
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fserver_005fname_005fget-1"></a>
<h4 class="subheading">gnutls_server_name_get</h4>
<a name="gnutls_005fserver_005fname_005fget"></a><dl>
<dt><a name="index-gnutls_005fserver_005fname_005fget"></a>Function: <em>int</em> <strong>gnutls_server_name_get</strong> <em>(gnutls_session_t <var>session</var>, void * <var>data</var>, size_t * <var>data_length</var>, unsigned int * <var>type</var>, unsigned int <var>indx</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>data</var>: will hold the data
</p>
<p><var>data_length</var>: will hold the data length. Must hold the maximum size of data.
</p>
<p><var>type</var>: will hold the server name indicator type
</p>
<p><var>indx</var>: is the index of the server_name
</p>
<p>This function will allow you to get the name indication (if any), a
client has sent.  The name indication may be any of the enumeration
gnutls_server_name_type_t.
</p>
<p>If  <code>type</code> is GNUTLS_NAME_DNS, then this function is to be used by
servers that support virtual hosting, and the data will be a null
terminated IDNA ACE string (prior to GnuTLS 3.4.0 it was a UTF-8 string).
</p>
<p>If  <code>data</code> has not enough size to hold the server name
GNUTLS_E_SHORT_MEMORY_BUFFER is returned, and  <code>data_length</code> will
hold the required size.
</p>
<p><code>index</code> is used to retrieve more than one server names (if sent by
the client).  The first server name has an index of 0, the second 1
and so on.  If no name with the given index exists
GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fserver_005fname_005fset-1"></a>
<h4 class="subheading">gnutls_server_name_set</h4>
<a name="gnutls_005fserver_005fname_005fset"></a><dl>
<dt><a name="index-gnutls_005fserver_005fname_005fset"></a>Function: <em>int</em> <strong>gnutls_server_name_set</strong> <em>(gnutls_session_t <var>session</var>, gnutls_server_name_type_t <var>type</var>, const void * <var>name</var>, size_t <var>name_length</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>type</var>: specifies the indicator type
</p>
<p><var>name</var>: is a string that contains the server name.
</p>
<p><var>name_length</var>: holds the length of name
</p>
<p>This function is to be used by clients that want to inform (via a
TLS extension mechanism) the server of the name they connected to.
This should be used by clients that connect to servers that do
virtual hosting.
</p>
<p>The value of  <code>name</code> depends on the  <code>type</code> type.  In case of
<code>GNUTLS_NAME_DNS</code> , a UTF-8 null-terminated domain name string,
without the trailing dot, is expected.
</p>
<p>IPv4 or IPv6 addresses are not permitted.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fsession_005fchannel_005fbinding-1"></a>
<h4 class="subheading">gnutls_session_channel_binding</h4>
<a name="gnutls_005fsession_005fchannel_005fbinding"></a><dl>
<dt><a name="index-gnutls_005fsession_005fchannel_005fbinding"></a>Function: <em>int</em> <strong>gnutls_session_channel_binding</strong> <em>(gnutls_session_t <var>session</var>, gnutls_channel_binding_t <var>cbtype</var>, gnutls_datum_t * <var>cb</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>cbtype</var>: an <code>gnutls_channel_binding_t</code>  enumeration type
</p>
<p><var>cb</var>: output buffer array with data
</p>
<p>Extract given channel binding data of the  <code>cbtype</code> (e.g.,
<code>GNUTLS_CB_TLS_UNIQUE</code> ) type.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success,
<code>GNUTLS_E_UNIMPLEMENTED_FEATURE</code>  if the  <code>cbtype</code> is unsupported,
<code>GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE</code>  if the data is not
currently available, or an error code.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fsession_005fenable_005fcompatibility_005fmode-1"></a>
<h4 class="subheading">gnutls_session_enable_compatibility_mode</h4>
<a name="gnutls_005fsession_005fenable_005fcompatibility_005fmode"></a><dl>
<dt><a name="index-gnutls_005fsession_005fenable_005fcompatibility_005fmode"></a>Function: <em>void</em> <strong>gnutls_session_enable_compatibility_mode</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function can be used to disable certain (security) features in
TLS in order to maintain maximum compatibility with buggy
clients. Because several trade-offs with security are enabled,
if required they will be reported through the audit subsystem.
</p>
<p>Normally only servers that require maximum compatibility with
everything out there, need to call this function.
</p>
<p>Note that this function must be called after any call to gnutls_priority
functions.
</p></dd></dl>

<a name="gnutls_005fsession_005fetm_005fstatus-1"></a>
<h4 class="subheading">gnutls_session_etm_status</h4>
<a name="gnutls_005fsession_005fetm_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fsession_005fetm_005fstatus"></a>Function: <em>unsigned</em> <strong>gnutls_session_etm_status</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Get the status of the encrypt-then-mac extension negotiation.
This is in accordance to rfc7366
</p>
<p><strong>Returns:</strong> Non-zero if the negotiation was successful or zero otherwise.
</p></dd></dl>

<a name="gnutls_005fsession_005fext_005fmaster_005fsecret_005fstatus-1"></a>
<h4 class="subheading">gnutls_session_ext_master_secret_status</h4>
<a name="gnutls_005fsession_005fext_005fmaster_005fsecret_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fsession_005fext_005fmaster_005fsecret_005fstatus"></a>Function: <em>unsigned</em> <strong>gnutls_session_ext_master_secret_status</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Get the status of the extended master secret extension negotiation.
This is in accordance to draft-ietf-tls-session-hash-01
</p>
<p><strong>Returns:</strong> Non-zero if the negotiation was successful or zero otherwise.
</p></dd></dl>

<a name="gnutls_005fsession_005fforce_005fvalid-1"></a>
<h4 class="subheading">gnutls_session_force_valid</h4>
<a name="gnutls_005fsession_005fforce_005fvalid"></a><dl>
<dt><a name="index-gnutls_005fsession_005fforce_005fvalid"></a>Function: <em>void</em> <strong>gnutls_session_force_valid</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Clears the invalid flag in a session. That means
that sessions were corrupt or invalid data were received 
can be re-used. Use only when debugging or experimenting
with the TLS protocol. Should not be used in typical
applications.
</p></dd></dl>

<a name="gnutls_005fsession_005fget_005fdata-1"></a>
<h4 class="subheading">gnutls_session_get_data</h4>
<a name="gnutls_005fsession_005fget_005fdata"></a><dl>
<dt><a name="index-gnutls_005fsession_005fget_005fdata"></a>Function: <em>int</em> <strong>gnutls_session_get_data</strong> <em>(gnutls_session_t <var>session</var>, void * <var>session_data</var>, size_t * <var>session_data_size</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>session_data</var>: is a pointer to space to hold the session.
</p>
<p><var>session_data_size</var>: is the session_data&rsquo;s size, or it will be set by the function.
</p>
<p>Returns all session parameters needed to be stored to support resumption.
The client should call this, and store the returned session data. A session
may be resumed later by calling <code>gnutls_session_set_data()</code> .  
This function must be called after a successful (full) handshake. It should
not be used in already resumed sessions &ndash;see <code>gnutls_session_is_resumed()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fsession_005fget_005fdata2-1"></a>
<h4 class="subheading">gnutls_session_get_data2</h4>
<a name="gnutls_005fsession_005fget_005fdata2"></a><dl>
<dt><a name="index-gnutls_005fsession_005fget_005fdata2"></a>Function: <em>int</em> <strong>gnutls_session_get_data2</strong> <em>(gnutls_session_t <var>session</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>data</var>: is a pointer to a datum that will hold the session.
</p>
<p>Returns all session parameters needed to be stored to support resumption.
The client should call this, and store the returned session data. A session
may be resumed later by calling <code>gnutls_session_set_data()</code> .  
This function must be called after a successful (full) handshake. It should
not be used in already resumed sessions &ndash;see <code>gnutls_session_is_resumed()</code> .
</p>
<p>The returned  <code>data</code> are allocated and must be released using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fsession_005fget_005fdesc-1"></a>
<h4 class="subheading">gnutls_session_get_desc</h4>
<a name="gnutls_005fsession_005fget_005fdesc"></a><dl>
<dt><a name="index-gnutls_005fsession_005fget_005fdesc"></a>Function: <em>char *</em> <strong>gnutls_session_get_desc</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p>This function returns a string describing the current session.
The string is null terminated and allocated using <code>gnutls_malloc()</code> .
</p>
<p>If initial negotiation is not complete when this function is called,
<code>NULL</code>  will be returned.
</p>
<p><strong>Returns:</strong> a description of the protocols and algorithms in the current session.
</p>
<p><strong>Since:</strong> 3.1.10
</p></dd></dl>

<a name="gnutls_005fsession_005fget_005fid-1"></a>
<h4 class="subheading">gnutls_session_get_id</h4>
<a name="gnutls_005fsession_005fget_005fid"></a><dl>
<dt><a name="index-gnutls_005fsession_005fget_005fid"></a>Function: <em>int</em> <strong>gnutls_session_get_id</strong> <em>(gnutls_session_t <var>session</var>, void * <var>session_id</var>, size_t * <var>session_id_size</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>session_id</var>: is a pointer to space to hold the session id.
</p>
<p><var>session_id_size</var>: initially should contain the maximum  <code>session_id</code> size and will be updated.
</p>
<p>Returns the current session ID. This can be used if you want to
check if the next session you tried to resume was actually
resumed.  That is because resumed sessions share the same session ID
with the original session.
</p>
<p>The session ID is selected by the server, that identify the
current session.  In all supported TLS protocols, the session id
is less than <code>GNUTLS_MAX_SESSION_ID_SIZE</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fsession_005fget_005fid2-1"></a>
<h4 class="subheading">gnutls_session_get_id2</h4>
<a name="gnutls_005fsession_005fget_005fid2"></a><dl>
<dt><a name="index-gnutls_005fsession_005fget_005fid2"></a>Function: <em>int</em> <strong>gnutls_session_get_id2</strong> <em>(gnutls_session_t <var>session</var>, gnutls_datum_t * <var>session_id</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>session_id</var>: will point to the session ID.
</p>
<p>Returns the current session ID. The returned data should be
treated as constant.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p>
<p><strong>Since:</strong> 3.1.4
</p></dd></dl>

<a name="gnutls_005fsession_005fget_005fptr-1"></a>
<h4 class="subheading">gnutls_session_get_ptr</h4>
<a name="gnutls_005fsession_005fget_005fptr"></a><dl>
<dt><a name="index-gnutls_005fsession_005fget_005fptr"></a>Function: <em>void *</em> <strong>gnutls_session_get_ptr</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Get user pointer for session.  Useful in callbacks.  This is the
pointer set with <code>gnutls_session_set_ptr()</code> .
</p>
<p><strong>Returns:</strong> the user given pointer from the session structure, or
<code>NULL</code>  if it was never set.
</p></dd></dl>

<a name="gnutls_005fsession_005fget_005frandom-1"></a>
<h4 class="subheading">gnutls_session_get_random</h4>
<a name="gnutls_005fsession_005fget_005frandom"></a><dl>
<dt><a name="index-gnutls_005fsession_005fget_005frandom"></a>Function: <em>void</em> <strong>gnutls_session_get_random</strong> <em>(gnutls_session_t <var>session</var>, gnutls_datum_t * <var>client</var>, gnutls_datum_t * <var>server</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>client</var>: the client part of the random
</p>
<p><var>server</var>: the server part of the random
</p>
<p>This function returns pointers to the client and server
random fields used in the TLS handshake. The pointers are
not to be modified or deallocated.
</p>
<p>If a client random value has not yet been established, the output
will be garbage.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fsession_005fget_005fverify_005fcert_005fstatus-1"></a>
<h4 class="subheading">gnutls_session_get_verify_cert_status</h4>
<a name="gnutls_005fsession_005fget_005fverify_005fcert_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fsession_005fget_005fverify_005fcert_005fstatus"></a>Function: <em>unsigned int</em> <strong>gnutls_session_get_verify_cert_status</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p>This function returns the status of the verification when initiated
via auto-verification, i.e., by <code>gnutls_session_set_verify_cert2()</code>  or
<code>gnutls_session_set_verify_cert()</code> . If no certificate verification
was occurred then the return value would be set to ((unsigned int)-1).
</p>
<p>The certificate verification status is the same as in <code>gnutls_certificate_verify_peers()</code> .
</p>
<p><strong>Returns:</strong> the certificate verification status.
</p>
<p><strong>Since:</strong> 3.4.6
</p></dd></dl>

<a name="gnutls_005fsession_005fis_005fresumed-1"></a>
<h4 class="subheading">gnutls_session_is_resumed</h4>
<a name="gnutls_005fsession_005fis_005fresumed"></a><dl>
<dt><a name="index-gnutls_005fsession_005fis_005fresumed-1"></a>Function: <em>int</em> <strong>gnutls_session_is_resumed</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Check whether session is resumed or not.
</p>
<p><strong>Returns:</strong> non zero if this session is resumed, or a zero if this is
a new session.
</p></dd></dl>

<a name="gnutls_005fsession_005fresumption_005frequested-1"></a>
<h4 class="subheading">gnutls_session_resumption_requested</h4>
<a name="gnutls_005fsession_005fresumption_005frequested"></a><dl>
<dt><a name="index-gnutls_005fsession_005fresumption_005frequested-1"></a>Function: <em>int</em> <strong>gnutls_session_resumption_requested</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Check whether the client has asked for session resumption.
This function is valid only on server side.
</p>
<p><strong>Returns:</strong> non zero if session resumption was asked, or a zero if not.
</p></dd></dl>

<a name="gnutls_005fsession_005fset_005fdata-1"></a>
<h4 class="subheading">gnutls_session_set_data</h4>
<a name="gnutls_005fsession_005fset_005fdata"></a><dl>
<dt><a name="index-gnutls_005fsession_005fset_005fdata"></a>Function: <em>int</em> <strong>gnutls_session_set_data</strong> <em>(gnutls_session_t <var>session</var>, const void * <var>session_data</var>, size_t <var>session_data_size</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>session_data</var>: is a pointer to space to hold the session.
</p>
<p><var>session_data_size</var>: is the session&rsquo;s size
</p>
<p>Sets all session parameters, in order to resume a previously
established session.  The session data given must be the one
returned by <code>gnutls_session_get_data()</code> .  This function should be
called before <code>gnutls_handshake()</code> .
</p>
<p>Keep in mind that session resuming is advisory. The server may
choose not to resume the session, thus a full handshake will be
performed.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fsession_005fset_005fid-1"></a>
<h4 class="subheading">gnutls_session_set_id</h4>
<a name="gnutls_005fsession_005fset_005fid"></a><dl>
<dt><a name="index-gnutls_005fsession_005fset_005fid"></a>Function: <em>int</em> <strong>gnutls_session_set_id</strong> <em>(gnutls_session_t <var>session</var>, const gnutls_datum_t * <var>sid</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>sid</var>: the session identifier
</p>
<p>This function sets the session ID to be used in a client hello.
This is a function intended for exceptional uses. Do not use this
function unless you are implementing a custom protocol.
</p>
<p>To set session resumption parameters use <code>gnutls_session_set_data()</code>  instead.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fsession_005fset_005fpremaster-1"></a>
<h4 class="subheading">gnutls_session_set_premaster</h4>
<a name="gnutls_005fsession_005fset_005fpremaster"></a><dl>
<dt><a name="index-gnutls_005fsession_005fset_005fpremaster"></a>Function: <em>int</em> <strong>gnutls_session_set_premaster</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>entity</var>, gnutls_protocol_t <var>version</var>, gnutls_kx_algorithm_t <var>kx</var>, gnutls_cipher_algorithm_t <var>cipher</var>, gnutls_mac_algorithm_t <var>mac</var>, gnutls_compression_method_t <var>comp</var>, const gnutls_datum_t * <var>master</var>, const gnutls_datum_t * <var>session_id</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>entity</var>: GNUTLS_SERVER or GNUTLS_CLIENT
</p>
<p><var>version</var>: the TLS protocol version
</p>
<p><var>kx</var>: the key exchange method
</p>
<p><var>cipher</var>: the cipher
</p>
<p><var>mac</var>: the MAC algorithm
</p>
<p><var>comp</var>: the compression method
</p>
<p><var>master</var>: the master key to use
</p>
<p><var>session_id</var>: the session identifier
</p>
<p>This function sets the premaster secret in a session. This is
a function intended for exceptional uses. Do not use this
function unless you are implementing a legacy protocol.
Use <code>gnutls_session_set_data()</code>  instead.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p></dd></dl>

<a name="gnutls_005fsession_005fset_005fptr-1"></a>
<h4 class="subheading">gnutls_session_set_ptr</h4>
<a name="gnutls_005fsession_005fset_005fptr"></a><dl>
<dt><a name="index-gnutls_005fsession_005fset_005fptr"></a>Function: <em>void</em> <strong>gnutls_session_set_ptr</strong> <em>(gnutls_session_t <var>session</var>, void * <var>ptr</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>ptr</var>: is the user pointer
</p>
<p>This function will set (associate) the user given pointer  <code>ptr</code> to
the session structure.  This pointer can be accessed with
<code>gnutls_session_get_ptr()</code> .
</p></dd></dl>

<a name="gnutls_005fsession_005fset_005fverify_005fcert-1"></a>
<h4 class="subheading">gnutls_session_set_verify_cert</h4>
<a name="gnutls_005fsession_005fset_005fverify_005fcert"></a><dl>
<dt><a name="index-gnutls_005fsession_005fset_005fverify_005fcert-1"></a>Function: <em>void</em> <strong>gnutls_session_set_verify_cert</strong> <em>(gnutls_session_t <var>session</var>, const char * <var>hostname</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p><var>hostname</var>: is the expected name of the peer; may be <code>NULL</code> 
</p>
<p><var>flags</var>: flags for certificate verification &ndash; <code>gnutls_certificate_verify_flags</code> 
</p>
<p>This function instructs GnuTLS to verify the peer&rsquo;s certificate
using the provided hostname. If the verification fails the handshake
will also fail with <code>GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR</code> . In that
case the verification result can be obtained using <code>gnutls_session_get_verify_cert_status()</code> .
</p>
<p>The  <code>hostname</code> pointer provided must remain valid for the lifetime
of the session. More precisely it should be available during any subsequent
handshakes. If no hostname is provided, no hostname verification
will be performed. For a more advanced verification function check
<code>gnutls_session_set_verify_cert2()</code> .
</p>
<p>The <code>gnutls_session_set_verify_cert()</code>  function is intended to be used by TLS
clients to verify the server&rsquo;s certificate.
</p>
<p><strong>Since:</strong> 3.4.6
</p></dd></dl>

<a name="gnutls_005fsession_005fset_005fverify_005fcert2-1"></a>
<h4 class="subheading">gnutls_session_set_verify_cert2</h4>
<a name="gnutls_005fsession_005fset_005fverify_005fcert2"></a><dl>
<dt><a name="index-gnutls_005fsession_005fset_005fverify_005fcert2"></a>Function: <em>void</em> <strong>gnutls_session_set_verify_cert2</strong> <em>(gnutls_session_t <var>session</var>, gnutls_typed_vdata_st * <var>data</var>, unsigned <var>elements</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p><var>data</var>: an array of typed data
</p>
<p><var>elements</var>: the number of data elements
</p>
<p><var>flags</var>: flags for certificate verification &ndash; <code>gnutls_certificate_verify_flags</code> 
</p>
<p>This function instructs GnuTLS to verify the peer&rsquo;s certificate
using the provided typed data information. If the verification fails the handshake
will also fail with <code>GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR</code> . In that
case the verification result can be obtained using <code>gnutls_session_get_verify_cert_status()</code> .
</p>
<p>The acceptable typed data are the same as in <code>gnutls_certificate_verify_peers()</code> ,
and once set must remain valid for the lifetime of the session. More precisely
they should be available during any subsequent handshakes.
</p>
<p><strong>Since:</strong> 3.4.6
</p></dd></dl>

<a name="gnutls_005fsession_005fset_005fverify_005ffunction-1"></a>
<h4 class="subheading">gnutls_session_set_verify_function</h4>
<a name="gnutls_005fsession_005fset_005fverify_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fsession_005fset_005fverify_005ffunction"></a>Function: <em>void</em> <strong>gnutls_session_set_verify_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_certificate_verify_function * <var>func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>func</var>: is the callback function
</p>
<p>This function sets a callback to be called when peer&rsquo;s certificate
has been received in order to verify it on receipt rather than
doing after the handshake is completed. This overrides any callback
set using <code>gnutls_certificate_set_verify_function()</code> .
</p>
<p>The callback&rsquo;s function prototype is:
int (*callback)(gnutls_session_t);
</p>
<p>If the callback function is provided then gnutls will call it, in the
handshake, just after the certificate message has been received.
To verify or obtain the certificate the <code>gnutls_certificate_verify_peers2()</code> ,
<code>gnutls_certificate_type_get()</code> , <code>gnutls_certificate_get_peers()</code>  functions
can be used.
</p>
<p>The callback function should return 0 for the handshake to continue
or non-zero to terminate.
</p>
<p><strong>Since:</strong> 3.4.6
</p></dd></dl>

<a name="gnutls_005fsession_005fticket_005fenable_005fclient-1"></a>
<h4 class="subheading">gnutls_session_ticket_enable_client</h4>
<a name="gnutls_005fsession_005fticket_005fenable_005fclient"></a><dl>
<dt><a name="index-gnutls_005fsession_005fticket_005fenable_005fclient"></a>Function: <em>int</em> <strong>gnutls_session_ticket_enable_client</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Request that the client should attempt session resumption using
SessionTicket.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fsession_005fticket_005fenable_005fserver-1"></a>
<h4 class="subheading">gnutls_session_ticket_enable_server</h4>
<a name="gnutls_005fsession_005fticket_005fenable_005fserver"></a><dl>
<dt><a name="index-gnutls_005fsession_005fticket_005fenable_005fserver-1"></a>Function: <em>int</em> <strong>gnutls_session_ticket_enable_server</strong> <em>(gnutls_session_t <var>session</var>, const gnutls_datum_t * <var>key</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>key</var>: key to encrypt session parameters.
</p>
<p>Request that the server should attempt session resumption using
SessionTicket.   <code>key</code> must be initialized with
<code>gnutls_session_ticket_key_generate()</code> , and should be overwritten
using <code>gnutls_memset()</code>  before being released.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fsession_005fticket_005fkey_005fgenerate-1"></a>
<h4 class="subheading">gnutls_session_ticket_key_generate</h4>
<a name="gnutls_005fsession_005fticket_005fkey_005fgenerate"></a><dl>
<dt><a name="index-gnutls_005fsession_005fticket_005fkey_005fgenerate-1"></a>Function: <em>int</em> <strong>gnutls_session_ticket_key_generate</strong> <em>(gnutls_datum_t * <var>key</var>)</em></dt>
<dd><p><var>key</var>: is a pointer to a <code>gnutls_datum_t</code>  which will contain a newly
created key.
</p>
<p>Generate a random key to encrypt security parameters within
SessionTicket.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fset_005fdefault_005fpriority-1"></a>
<h4 class="subheading">gnutls_set_default_priority</h4>
<a name="gnutls_005fset_005fdefault_005fpriority"></a><dl>
<dt><a name="index-gnutls_005fset_005fdefault_005fpriority"></a>Function: <em>int</em> <strong>gnutls_set_default_priority</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Sets the default priority on the ciphers, key exchange methods,
macs and compression methods. For more fine-tuning you could
use <code>gnutls_priority_set_direct()</code>  or <code>gnutls_priority_set()</code>  instead.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fsign_005falgorithm_005fget-1"></a>
<h4 class="subheading">gnutls_sign_algorithm_get</h4>
<a name="gnutls_005fsign_005falgorithm_005fget"></a><dl>
<dt><a name="index-gnutls_005fsign_005falgorithm_005fget"></a>Function: <em>int</em> <strong>gnutls_sign_algorithm_get</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Returns the signature algorithm that is (or will be) used in this 
session by the server to sign data.
</p>
<p><strong>Returns:</strong> The sign algorithm or <code>GNUTLS_SIGN_UNKNOWN</code> .
</p>
<p><strong>Since:</strong> 3.1.1
</p></dd></dl>

<a name="gnutls_005fsign_005falgorithm_005fget_005fclient-1"></a>
<h4 class="subheading">gnutls_sign_algorithm_get_client</h4>
<a name="gnutls_005fsign_005falgorithm_005fget_005fclient"></a><dl>
<dt><a name="index-gnutls_005fsign_005falgorithm_005fget_005fclient"></a>Function: <em>int</em> <strong>gnutls_sign_algorithm_get_client</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Returns the signature algorithm that is (or will be) used in this 
session by the client to sign data.
</p>
<p><strong>Returns:</strong> The sign algorithm or <code>GNUTLS_SIGN_UNKNOWN</code> .
</p>
<p><strong>Since:</strong> 3.1.11
</p></dd></dl>

<a name="gnutls_005fsign_005falgorithm_005fget_005frequested-1"></a>
<h4 class="subheading">gnutls_sign_algorithm_get_requested</h4>
<a name="gnutls_005fsign_005falgorithm_005fget_005frequested"></a><dl>
<dt><a name="index-gnutls_005fsign_005falgorithm_005fget_005frequested"></a>Function: <em>int</em> <strong>gnutls_sign_algorithm_get_requested</strong> <em>(gnutls_session_t <var>session</var>, size_t <var>indx</var>, gnutls_sign_algorithm_t * <var>algo</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>indx</var>: is an index of the signature algorithm to return
</p>
<p><var>algo</var>: the returned certificate type will be stored there
</p>
<p>Returns the signature algorithm specified by index that was
requested by the peer. If the specified index has no data available
this function returns <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> .  If
the negotiated TLS version does not support signature algorithms
then <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be returned even
for the first index.  The first index is 0.
</p>
<p>This function is useful in the certificate callback functions
to assist in selecting the correct certificate.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise
an error code is returned.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fsign_005fget_005fhash_005falgorithm-1"></a>
<h4 class="subheading">gnutls_sign_get_hash_algorithm</h4>
<a name="gnutls_005fsign_005fget_005fhash_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fsign_005fget_005fhash_005falgorithm"></a>Function: <em>gnutls_digest_algorithm_t</em> <strong>gnutls_sign_get_hash_algorithm</strong> <em>(gnutls_sign_algorithm_t <var>sign</var>)</em></dt>
<dd><p><var>sign</var>: is a signature algorithm
</p>
<p>This function returns the digest algorithm corresponding to
the given signature algorithms.
</p>
<p><strong>Since:</strong> 3.1.1
</p>
<p><strong>Returns:</strong> return a <code>gnutls_digest_algorithm_t</code>  value, or <code>GNUTLS_DIG_UNKNOWN</code>  on error.
</p></dd></dl>

<a name="gnutls_005fsign_005fget_005fid-1"></a>
<h4 class="subheading">gnutls_sign_get_id</h4>
<a name="gnutls_005fsign_005fget_005fid"></a><dl>
<dt><a name="index-gnutls_005fsign_005fget_005fid"></a>Function: <em>gnutls_sign_algorithm_t</em> <strong>gnutls_sign_get_id</strong> <em>(const char * <var>name</var>)</em></dt>
<dd><p><var>name</var>: is a sign algorithm name
</p>
<p>The names are compared in a case insensitive way.
</p>
<p><strong>Returns:</strong> return a <code>gnutls_sign_algorithm_t</code>  value corresponding to
the specified algorithm, or <code>GNUTLS_SIGN_UNKNOWN</code>  on error.
</p></dd></dl>

<a name="gnutls_005fsign_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_sign_get_name</h4>
<a name="gnutls_005fsign_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fsign_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_sign_get_name</strong> <em>(gnutls_sign_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is a sign algorithm
</p>
<p>Convert a <code>gnutls_sign_algorithm_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified sign
algorithm, or <code>NULL</code> .
</p></dd></dl>

<a name="gnutls_005fsign_005fget_005foid-1"></a>
<h4 class="subheading">gnutls_sign_get_oid</h4>
<a name="gnutls_005fsign_005fget_005foid"></a><dl>
<dt><a name="index-gnutls_005fsign_005fget_005foid"></a>Function: <em>const char *</em> <strong>gnutls_sign_get_oid</strong> <em>(gnutls_sign_algorithm_t <var>sign</var>)</em></dt>
<dd><p><var>sign</var>: is a sign algorithm
</p>
<p>Convert a <code>gnutls_sign_algorithm_t</code>  value to its object identifier.
</p>
<p><strong>Returns:</strong> a string that contains the object identifier of the specified sign
algorithm, or <code>NULL</code> .
</p>
<p><strong>Since:</strong> 3.4.3
</p></dd></dl>

<a name="gnutls_005fsign_005fget_005fpk_005falgorithm-1"></a>
<h4 class="subheading">gnutls_sign_get_pk_algorithm</h4>
<a name="gnutls_005fsign_005fget_005fpk_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fsign_005fget_005fpk_005falgorithm"></a>Function: <em>gnutls_pk_algorithm_t</em> <strong>gnutls_sign_get_pk_algorithm</strong> <em>(gnutls_sign_algorithm_t <var>sign</var>)</em></dt>
<dd><p><var>sign</var>: is a signature algorithm
</p>
<p>This function returns the public key algorithm corresponding to
the given signature algorithms.
</p>
<p><strong>Since:</strong> 3.1.1
</p>
<p><strong>Returns:</strong> return a <code>gnutls_pk_algorithm_t</code>  value, or <code>GNUTLS_PK_UNKNOWN</code>  on error.
</p></dd></dl>

<a name="gnutls_005fsign_005fis_005fsecure-1"></a>
<h4 class="subheading">gnutls_sign_is_secure</h4>
<a name="gnutls_005fsign_005fis_005fsecure"></a><dl>
<dt><a name="index-gnutls_005fsign_005fis_005fsecure"></a>Function: <em>int</em> <strong>gnutls_sign_is_secure</strong> <em>(gnutls_sign_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is a sign algorithm
</p>

<p><strong>Returns:</strong> Non-zero if the provided signature algorithm is considered to be secure.
</p></dd></dl>

<a name="gnutls_005fsign_005flist-1"></a>
<h4 class="subheading">gnutls_sign_list</h4>
<a name="gnutls_005fsign_005flist"></a><dl>
<dt><a name="index-gnutls_005fsign_005flist"></a>Function: <em>const gnutls_sign_algorithm_t *</em> <strong>gnutls_sign_list</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>Get a list of supported public key signature algorithms.
</p>
<p><strong>Returns:</strong> a (0)-terminated list of <code>gnutls_sign_algorithm_t</code> 
integers indicating the available ciphers.
</p></dd></dl>

<a name="gnutls_005fsrp_005fallocate_005fclient_005fcredentials-1"></a>
<h4 class="subheading">gnutls_srp_allocate_client_credentials</h4>
<a name="gnutls_005fsrp_005fallocate_005fclient_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fallocate_005fclient_005fcredentials"></a>Function: <em>int</em> <strong>gnutls_srp_allocate_client_credentials</strong> <em>(gnutls_srp_client_credentials_t *            <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a pointer to a <code>gnutls_srp_server_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus
this helper function is provided in order to allocate it.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p></dd></dl>

<a name="gnutls_005fsrp_005fallocate_005fserver_005fcredentials-1"></a>
<h4 class="subheading">gnutls_srp_allocate_server_credentials</h4>
<a name="gnutls_005fsrp_005fallocate_005fserver_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fallocate_005fserver_005fcredentials"></a>Function: <em>int</em> <strong>gnutls_srp_allocate_server_credentials</strong> <em>(gnutls_srp_server_credentials_t *            <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a pointer to a <code>gnutls_srp_server_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus this
helper function is provided in order to allocate it.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p></dd></dl>

<a name="gnutls_005fsrp_005fbase64_005fdecode-1"></a>
<h4 class="subheading">gnutls_srp_base64_decode</h4>
<a name="gnutls_005fsrp_005fbase64_005fdecode"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fbase64_005fdecode"></a>Function: <em>int</em> <strong>gnutls_srp_base64_decode</strong> <em>(const gnutls_datum_t * <var>b64_data</var>, char * <var>result</var>, size_t * <var>result_size</var>)</em></dt>
<dd><p><var>b64_data</var>: contain the encoded data
</p>
<p><var>result</var>: the place where decoded data will be copied
</p>
<p><var>result_size</var>: holds the size of the result
</p>
<p>This function will decode the given encoded data, using the base64
encoding found in libsrp.
</p>
<p>Note that  <code>b64_data</code> should be null terminated.
</p>
<p>Warning!  This base64 encoding is not the &quot;standard&quot; encoding, so
do not use it for non-SRP purposes.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the buffer given is not
long enough, or 0 on success.
</p></dd></dl>

<a name="gnutls_005fsrp_005fbase64_005fdecode2-1"></a>
<h4 class="subheading">gnutls_srp_base64_decode2</h4>
<a name="gnutls_005fsrp_005fbase64_005fdecode2"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fbase64_005fdecode2"></a>Function: <em>int</em> <strong>gnutls_srp_base64_decode2</strong> <em>(const gnutls_datum_t * <var>b64_data</var>, gnutls_datum_t * <var>result</var>)</em></dt>
<dd><p><var>b64_data</var>: contains the encoded data
</p>
<p><var>result</var>: the place where decoded data lie
</p>
<p>This function will decode the given encoded data. The decoded data
will be allocated, and stored into result.  It will decode using
the base64 algorithm as used in libsrp.
</p>
<p>You should use <code>gnutls_free()</code>  to free the returned data.
</p>
<p>Warning!  This base64 encoding is not the &quot;standard&quot; encoding, so
do not use it for non-SRP purposes.
</p>
<p><strong>Returns:</strong> 0 on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fsrp_005fbase64_005fencode-1"></a>
<h4 class="subheading">gnutls_srp_base64_encode</h4>
<a name="gnutls_005fsrp_005fbase64_005fencode"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fbase64_005fencode"></a>Function: <em>int</em> <strong>gnutls_srp_base64_encode</strong> <em>(const gnutls_datum_t * <var>data</var>, char * <var>result</var>, size_t * <var>result_size</var>)</em></dt>
<dd><p><var>data</var>: contain the raw data
</p>
<p><var>result</var>: the place where base64 data will be copied
</p>
<p><var>result_size</var>: holds the size of the result
</p>
<p>This function will convert the given data to printable data, using
the base64 encoding, as used in the libsrp.  This is the encoding
used in SRP password files.  If the provided buffer is not long
enough GNUTLS_E_SHORT_MEMORY_BUFFER is returned.
</p>
<p>Warning!  This base64 encoding is not the &quot;standard&quot; encoding, so
do not use it for non-SRP purposes.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the buffer given is not
long enough, or 0 on success.
</p></dd></dl>

<a name="gnutls_005fsrp_005fbase64_005fencode2-1"></a>
<h4 class="subheading">gnutls_srp_base64_encode2</h4>
<a name="gnutls_005fsrp_005fbase64_005fencode2"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fbase64_005fencode2"></a>Function: <em>int</em> <strong>gnutls_srp_base64_encode2</strong> <em>(const gnutls_datum_t * <var>data</var>, gnutls_datum_t * <var>result</var>)</em></dt>
<dd><p><var>data</var>: contains the raw data
</p>
<p><var>result</var>: will hold the newly allocated encoded data
</p>
<p>This function will convert the given data to printable data, using
the base64 encoding.  This is the encoding used in SRP password
files.  This function will allocate the required memory to hold
the encoded data.
</p>
<p>You should use <code>gnutls_free()</code>  to free the returned data.
</p>
<p>Warning!  This base64 encoding is not the &quot;standard&quot; encoding, so
do not use it for non-SRP purposes.
</p>
<p><strong>Returns:</strong> 0 on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fsrp_005ffree_005fclient_005fcredentials-1"></a>
<h4 class="subheading">gnutls_srp_free_client_credentials</h4>
<a name="gnutls_005fsrp_005ffree_005fclient_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fsrp_005ffree_005fclient_005fcredentials"></a>Function: <em>void</em> <strong>gnutls_srp_free_client_credentials</strong> <em>(gnutls_srp_client_credentials_t <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_srp_client_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus
this helper function is provided in order to free (deallocate) it.
</p></dd></dl>

<a name="gnutls_005fsrp_005ffree_005fserver_005fcredentials-1"></a>
<h4 class="subheading">gnutls_srp_free_server_credentials</h4>
<a name="gnutls_005fsrp_005ffree_005fserver_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fsrp_005ffree_005fserver_005fcredentials"></a>Function: <em>void</em> <strong>gnutls_srp_free_server_credentials</strong> <em>(gnutls_srp_server_credentials_t <var>sc</var>)</em></dt>
<dd><p><var>sc</var>: is a <code>gnutls_srp_server_credentials_t</code>  type.
</p>
<p>This structure is complex enough to manipulate directly thus
this helper function is provided in order to free (deallocate) it.
</p></dd></dl>

<a name="gnutls_005fsrp_005fserver_005fget_005fusername-1"></a>
<h4 class="subheading">gnutls_srp_server_get_username</h4>
<a name="gnutls_005fsrp_005fserver_005fget_005fusername"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fserver_005fget_005fusername"></a>Function: <em>const char *</em> <strong>gnutls_srp_server_get_username</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a gnutls session
</p>
<p>This function will return the username of the peer.  This should
only be called in case of SRP authentication and in case of a
server.  Returns NULL in case of an error.
</p>
<p><strong>Returns:</strong> SRP username of the peer, or NULL in case of error.
</p></dd></dl>

<a name="gnutls_005fsrp_005fset_005fclient_005fcredentials-1"></a>
<h4 class="subheading">gnutls_srp_set_client_credentials</h4>
<a name="gnutls_005fsrp_005fset_005fclient_005fcredentials"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fset_005fclient_005fcredentials"></a>Function: <em>int</em> <strong>gnutls_srp_set_client_credentials</strong> <em>(gnutls_srp_client_credentials_t <var>res</var>, const char * <var>username</var>, const char * <var>password</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_srp_client_credentials_t</code>  type.
</p>
<p><var>username</var>: is the user&rsquo;s userid
</p>
<p><var>password</var>: is the user&rsquo;s password
</p>
<p>This function sets the username and password, in a
<code>gnutls_srp_client_credentials_t</code>  type.  Those will be used in
SRP authentication.   <code>username</code> and  <code>password</code> should be ASCII
strings or UTF-8 strings prepared using the &quot;SASLprep&quot; profile of
&quot;stringprep&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p></dd></dl>

<a name="gnutls_005fsrp_005fset_005fclient_005fcredentials_005ffunction-1"></a>
<h4 class="subheading">gnutls_srp_set_client_credentials_function</h4>
<a name="gnutls_005fsrp_005fset_005fclient_005fcredentials_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fset_005fclient_005fcredentials_005ffunction-1"></a>Function: <em>void</em> <strong>gnutls_srp_set_client_credentials_function</strong> <em>(gnutls_srp_client_credentials_t         <var>cred</var>, gnutls_srp_client_credentials_function         * <var>func</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_srp_server_credentials_t</code>  type.
</p>
<p><var>func</var>: is the callback function
</p>
<p>This function can be used to set a callback to retrieve the
username and password for client SRP authentication.  The
callback&rsquo;s function form is:
</p>
<p>int (*callback)(gnutls_session_t, char** username, char**password);
</p>
<p>The  <code>username</code> and  <code>password</code> must be allocated using
<code>gnutls_malloc()</code> .   <code>username</code> and  <code>password</code> should be ASCII strings
or UTF-8 strings prepared using the &quot;SASLprep&quot; profile of
&quot;stringprep&quot;.
</p>
<p>The callback function will be called once per handshake before the
initial hello message is sent.
</p>
<p>The callback should not return a negative error code the second
time called, since the handshake procedure will be aborted.
</p>
<p>The callback function should return 0 on success.
-1 indicates an error.
</p></dd></dl>

<a name="gnutls_005fsrp_005fset_005fprime_005fbits-1"></a>
<h4 class="subheading">gnutls_srp_set_prime_bits</h4>
<a name="gnutls_005fsrp_005fset_005fprime_005fbits"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fset_005fprime_005fbits"></a>Function: <em>void</em> <strong>gnutls_srp_set_prime_bits</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>bits</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>bits</var>: is the number of bits
</p>
<p>This function sets the minimum accepted number of bits, for use in
an SRP key exchange.  If zero, the default 2048 bits will be used.
</p>
<p>In the client side it sets the minimum accepted number of bits.  If
a server sends a prime with less bits than that
<code>GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER</code>  will be returned by the
handshake.
</p>
<p>This function has no effect in server side.
</p>
<p><strong>Since:</strong> 2.6.0
</p></dd></dl>

<a name="gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffile-1"></a>
<h4 class="subheading">gnutls_srp_set_server_credentials_file</h4>
<a name="gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffile"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffile-1"></a>Function: <em>int</em> <strong>gnutls_srp_set_server_credentials_file</strong> <em>(gnutls_srp_server_credentials_t <var>res</var>, const char * <var>password_file</var>, const char * <var>password_conf_file</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_srp_server_credentials_t</code>  type.
</p>
<p><var>password_file</var>: is the SRP password file (tpasswd)
</p>
<p><var>password_conf_file</var>: is the SRP password conf file (tpasswd.conf)
</p>
<p>This function sets the password files, in a
<code>gnutls_srp_server_credentials_t</code>  type.  Those password files
hold usernames and verifiers and will be used for SRP
authentication.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p></dd></dl>

<a name="gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffunction-1"></a>
<h4 class="subheading">gnutls_srp_set_server_credentials_function</h4>
<a name="gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffunction-1"></a>Function: <em>void</em> <strong>gnutls_srp_set_server_credentials_function</strong> <em>(gnutls_srp_server_credentials_t         <var>cred</var>, gnutls_srp_server_credentials_function         * <var>func</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_srp_server_credentials_t</code>  type.
</p>
<p><var>func</var>: is the callback function
</p>
<p>This function can be used to set a callback to retrieve the user&rsquo;s
SRP credentials.  The callback&rsquo;s function form is:
</p>
<p>int (*callback)(gnutls_session_t, const char* username,
gnutls_datum_t *salt, gnutls_datum_t *verifier, gnutls_datum_t *generator,
gnutls_datum_t *prime);
</p>
<p><code>username</code> contains the actual username.
The  <code>salt</code> ,  <code>verifier</code> ,  <code>generator</code> and  <code>prime</code> must be filled
in using the <code>gnutls_malloc()</code> . For convenience  <code>prime</code> and  <code>generator</code> may also be one of the static parameters defined in gnutls.h.
</p>
<p>Initially, the data field is NULL in every <code>gnutls_datum_t</code> 
structure that the callback has to fill in. When the
callback is done GnuTLS deallocates all of those buffers
which are non-NULL, regardless of the return value.
</p>
<p>In order to prevent attackers from guessing valid usernames,
if a user does not exist, g and n values should be filled in
using a random user&rsquo;s parameters. In that case the callback must
return the special value (1).
See <code>gnutls_srp_set_server_fake_salt_seed</code>  too.
If this is not required for your application, return a negative
number from the callback to abort the handshake.
</p>
<p>The callback function will only be called once per handshake.
The callback function should return 0 on success, while
-1 indicates an error.
</p></dd></dl>

<a name="gnutls_005fsrp_005fset_005fserver_005ffake_005fsalt_005fseed-1"></a>
<h4 class="subheading">gnutls_srp_set_server_fake_salt_seed</h4>
<a name="gnutls_005fsrp_005fset_005fserver_005ffake_005fsalt_005fseed"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fset_005fserver_005ffake_005fsalt_005fseed"></a>Function: <em>void</em> <strong>gnutls_srp_set_server_fake_salt_seed</strong> <em>(gnutls_srp_server_credentials_t <var>cred</var>, const gnutls_datum_t * <var>seed</var>, unsigned int <var>salt_length</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_srp_server_credentials_t</code>  type
</p>
<p><var>seed</var>: is the seed data, only needs to be valid until the function
returns; size of the seed must be greater than zero
</p>
<p><var>salt_length</var>: is the length of the generated fake salts
</p>
<p>This function sets the seed that is used to generate salts for
invalid (non-existent) usernames.
</p>
<p>In order to prevent attackers from guessing valid usernames,
when a user does not exist gnutls generates a salt and a verifier
and proceeds with the protocol as usual.
The authentication will ultimately fail, but the client cannot tell
whether the username is valid (exists) or invalid.
</p>
<p>If an attacker learns the seed, given a salt (which is part of the
handshake) which was generated when the seed was in use, it can tell
whether or not the authentication failed because of an unknown username.
This seed cannot be used to reveal application data or passwords.
</p>
<p><code>salt_length</code> should represent the salt length your application uses.
Generating fake salts longer than 20 bytes is not supported.
</p>
<p>By default the seed is a random value, different each time a
<code>gnutls_srp_server_credentials_t</code>  is allocated and fake salts are
16 bytes long.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fsrp_005fverifier-1"></a>
<h4 class="subheading">gnutls_srp_verifier</h4>
<a name="gnutls_005fsrp_005fverifier"></a><dl>
<dt><a name="index-gnutls_005fsrp_005fverifier-1"></a>Function: <em>int</em> <strong>gnutls_srp_verifier</strong> <em>(const char * <var>username</var>, const char * <var>password</var>, const gnutls_datum_t * <var>salt</var>, const gnutls_datum_t * <var>generator</var>, const gnutls_datum_t * <var>prime</var>, gnutls_datum_t * <var>res</var>)</em></dt>
<dd><p><var>username</var>: is the user&rsquo;s name
</p>
<p><var>password</var>: is the user&rsquo;s password
</p>
<p><var>salt</var>: should be some randomly generated bytes
</p>
<p><var>generator</var>: is the generator of the group
</p>
<p><var>prime</var>: is the group&rsquo;s prime
</p>
<p><var>res</var>: where the verifier will be stored.
</p>
<p>This function will create an SRP verifier, as specified in
RFC2945.  The  <code>prime</code> and  <code>generator</code> should be one of the static
parameters defined in gnutls/gnutls.h or may be generated.
</p>
<p>The verifier will be allocated with  <code>gnutls_malloc</code> () and will be stored in
 <code>res</code> using binary format.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or an
error code.
</p></dd></dl>

<a name="gnutls_005fsrtp_005fget_005fkeys-1"></a>
<h4 class="subheading">gnutls_srtp_get_keys</h4>
<a name="gnutls_005fsrtp_005fget_005fkeys"></a><dl>
<dt><a name="index-gnutls_005fsrtp_005fget_005fkeys-1"></a>Function: <em>int</em> <strong>gnutls_srtp_get_keys</strong> <em>(gnutls_session_t <var>session</var>, void * <var>key_material</var>, unsigned int <var>key_material_size</var>, gnutls_datum_t * <var>client_key</var>, gnutls_datum_t * <var>client_salt</var>, gnutls_datum_t * <var>server_key</var>, gnutls_datum_t * <var>server_salt</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>key_material</var>: Space to hold the generated key material
</p>
<p><var>key_material_size</var>: The maximum size of the key material
</p>
<p><var>client_key</var>: The master client write key, pointing inside the key material
</p>
<p><var>client_salt</var>: The master client write salt, pointing inside the key material
</p>
<p><var>server_key</var>: The master server write key, pointing inside the key material
</p>
<p><var>server_salt</var>: The master server write salt, pointing inside the key material
</p>
<p>This is a helper function to generate the keying material for SRTP.
It requires the space of the key material to be pre-allocated (should be at least
2x the maximum key size and salt size). The  <code>client_key</code> ,  <code>client_salt</code> ,  <code>server_key</code> and  <code>server_salt</code> are convenience datums that point inside the key material. They may
be <code>NULL</code> .
</p>
<p><strong>Returns:</strong> On success the size of the key material is returned,
otherwise, <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the buffer given is not 
sufficient, or a negative error code.
</p>
<p>Since 3.1.4
</p></dd></dl>

<a name="gnutls_005fsrtp_005fget_005fmki-1"></a>
<h4 class="subheading">gnutls_srtp_get_mki</h4>
<a name="gnutls_005fsrtp_005fget_005fmki"></a><dl>
<dt><a name="index-gnutls_005fsrtp_005fget_005fmki"></a>Function: <em>int</em> <strong>gnutls_srtp_get_mki</strong> <em>(gnutls_session_t <var>session</var>, gnutls_datum_t * <var>mki</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>mki</var>: will hold the MKI
</p>
<p>This function exports the negotiated Master Key Identifier,
received by the peer if any. The returned value in  <code>mki</code> should be 
treated as constant and valid only during the session&rsquo;s lifetime.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p>Since 3.1.4
</p></dd></dl>

<a name="gnutls_005fsrtp_005fget_005fprofile_005fid-1"></a>
<h4 class="subheading">gnutls_srtp_get_profile_id</h4>
<a name="gnutls_005fsrtp_005fget_005fprofile_005fid"></a><dl>
<dt><a name="index-gnutls_005fsrtp_005fget_005fprofile_005fid"></a>Function: <em>int</em> <strong>gnutls_srtp_get_profile_id</strong> <em>(const char * <var>name</var>, gnutls_srtp_profile_t * <var>profile</var>)</em></dt>
<dd><p><var>name</var>: The name of the profile to look up
</p>
<p><var>profile</var>: Will hold the profile id
</p>
<p>This function allows you to look up a profile based on a string.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p>Since 3.1.4
</p></dd></dl>

<a name="gnutls_005fsrtp_005fget_005fprofile_005fname-1"></a>
<h4 class="subheading">gnutls_srtp_get_profile_name</h4>
<a name="gnutls_005fsrtp_005fget_005fprofile_005fname"></a><dl>
<dt><a name="index-gnutls_005fsrtp_005fget_005fprofile_005fname"></a>Function: <em>const char *</em> <strong>gnutls_srtp_get_profile_name</strong> <em>(gnutls_srtp_profile_t <var>profile</var>)</em></dt>
<dd><p><var>profile</var>: The profile to look up a string for
</p>
<p>This function allows you to get the corresponding name for a
SRTP protection profile.
</p>
<p><strong>Returns:</strong> On success, the name of a SRTP profile as a string,
otherwise NULL.
</p>
<p>Since 3.1.4
</p></dd></dl>

<a name="gnutls_005fsrtp_005fget_005fselected_005fprofile-1"></a>
<h4 class="subheading">gnutls_srtp_get_selected_profile</h4>
<a name="gnutls_005fsrtp_005fget_005fselected_005fprofile"></a><dl>
<dt><a name="index-gnutls_005fsrtp_005fget_005fselected_005fprofile"></a>Function: <em>int</em> <strong>gnutls_srtp_get_selected_profile</strong> <em>(gnutls_session_t <var>session</var>, gnutls_srtp_profile_t * <var>profile</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>profile</var>: will hold the profile
</p>
<p>This function allows you to get the negotiated SRTP profile.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p>Since 3.1.4
</p></dd></dl>

<a name="gnutls_005fsrtp_005fset_005fmki-1"></a>
<h4 class="subheading">gnutls_srtp_set_mki</h4>
<a name="gnutls_005fsrtp_005fset_005fmki"></a><dl>
<dt><a name="index-gnutls_005fsrtp_005fset_005fmki"></a>Function: <em>int</em> <strong>gnutls_srtp_set_mki</strong> <em>(gnutls_session_t <var>session</var>, const gnutls_datum_t * <var>mki</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>mki</var>: holds the MKI
</p>
<p>This function sets the Master Key Identifier, to be
used by this session (if any).
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p>Since 3.1.4
</p></dd></dl>

<a name="gnutls_005fsrtp_005fset_005fprofile-1"></a>
<h4 class="subheading">gnutls_srtp_set_profile</h4>
<a name="gnutls_005fsrtp_005fset_005fprofile"></a><dl>
<dt><a name="index-gnutls_005fsrtp_005fset_005fprofile"></a>Function: <em>int</em> <strong>gnutls_srtp_set_profile</strong> <em>(gnutls_session_t <var>session</var>, gnutls_srtp_profile_t <var>profile</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>profile</var>: is the profile id to add.
</p>
<p>This function is to be used by both clients and servers, to declare
what SRTP profiles they support, to negotiate with the peer.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p>
<p>Since 3.1.4
</p></dd></dl>

<a name="gnutls_005fsrtp_005fset_005fprofile_005fdirect-1"></a>
<h4 class="subheading">gnutls_srtp_set_profile_direct</h4>
<a name="gnutls_005fsrtp_005fset_005fprofile_005fdirect"></a><dl>
<dt><a name="index-gnutls_005fsrtp_005fset_005fprofile_005fdirect"></a>Function: <em>int</em> <strong>gnutls_srtp_set_profile_direct</strong> <em>(gnutls_session_t <var>session</var>, const char * <var>profiles</var>, const char ** <var>err_pos</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>profiles</var>: is a string that contains the supported SRTP profiles,
separated by colons.
</p>
<p><var>err_pos</var>: In case of an error this will have the position in the string the error occurred, may be NULL.
</p>
<p>This function is to be used by both clients and servers, to declare
what SRTP profiles they support, to negotiate with the peer.
</p>
<p><strong>Returns:</strong> On syntax error <code>GNUTLS_E_INVALID_REQUEST</code>  is returned,
<code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p>
<p>Since 3.1.4
</p></dd></dl>

<a name="gnutls_005fstore_005fcommitment-1"></a>
<h4 class="subheading">gnutls_store_commitment</h4>
<a name="gnutls_005fstore_005fcommitment"></a><dl>
<dt><a name="index-gnutls_005fstore_005fcommitment-1"></a>Function: <em>int</em> <strong>gnutls_store_commitment</strong> <em>(const char * <var>db_name</var>, gnutls_tdb_t <var>tdb</var>, const char * <var>host</var>, const char * <var>service</var>, gnutls_digest_algorithm_t <var>hash_algo</var>, const gnutls_datum_t * <var>hash</var>, time_t <var>expiration</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>db_name</var>: A file specifying the stored keys (use NULL for the default)
</p>
<p><var>tdb</var>: A storage structure or NULL to use the default
</p>
<p><var>host</var>: The peer&rsquo;s name
</p>
<p><var>service</var>: non-NULL if this key is specific to a service (e.g. http)
</p>
<p><var>hash_algo</var>: The hash algorithm type
</p>
<p><var>hash</var>: The raw hash
</p>
<p><var>expiration</var>: The expiration time (use 0 to disable expiration)
</p>
<p><var>flags</var>: should be 0.
</p>
<p>This function will store the provided hash commitment to 
the list of stored public keys. The key with the given
hash will be considered valid until the provided expiration time.
</p>
<p>The  <code>store</code> variable if non-null specifies a custom backend for
the storage of entries. If it is NULL then the
default file backend will be used.
</p>
<p>Note that this function is not thread safe with the default backend.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fstore_005fpubkey-1"></a>
<h4 class="subheading">gnutls_store_pubkey</h4>
<a name="gnutls_005fstore_005fpubkey"></a><dl>
<dt><a name="index-gnutls_005fstore_005fpubkey-1"></a>Function: <em>int</em> <strong>gnutls_store_pubkey</strong> <em>(const char * <var>db_name</var>, gnutls_tdb_t <var>tdb</var>, const char * <var>host</var>, const char * <var>service</var>, gnutls_certificate_type_t <var>cert_type</var>, const gnutls_datum_t * <var>cert</var>, time_t <var>expiration</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>db_name</var>: A file specifying the stored keys (use NULL for the default)
</p>
<p><var>tdb</var>: A storage structure or NULL to use the default
</p>
<p><var>host</var>: The peer&rsquo;s name
</p>
<p><var>service</var>: non-NULL if this key is specific to a service (e.g. http)
</p>
<p><var>cert_type</var>: The type of the certificate
</p>
<p><var>cert</var>: The data of the certificate
</p>
<p><var>expiration</var>: The expiration time (use 0 to disable expiration)
</p>
<p><var>flags</var>: should be 0.
</p>
<p>This function will store the provided (raw or DER-encoded) certificate to 
the list of stored public keys. The key will be considered valid until 
the provided expiration time.
</p>
<p>The  <code>store</code> variable if non-null specifies a custom backend for
the storage of entries. If it is NULL then the
default file backend will be used.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0.13
</p></dd></dl>

<a name="gnutls_005fstrerror-1"></a>
<h4 class="subheading">gnutls_strerror</h4>
<a name="gnutls_005fstrerror"></a><dl>
<dt><a name="index-gnutls_005fstrerror"></a>Function: <em>const char *</em> <strong>gnutls_strerror</strong> <em>(int <var>error</var>)</em></dt>
<dd><p><var>error</var>: is a GnuTLS error code, a negative error code
</p>
<p>This function is similar to strerror.  The difference is that it
accepts an error number returned by a gnutls function; In case of
an unknown error a descriptive string is sent instead of <code>NULL</code> .
</p>
<p>Error codes are always a negative error code.
</p>
<p><strong>Returns:</strong> A string explaining the GnuTLS error message.
</p></dd></dl>

<a name="gnutls_005fstrerror_005fname-1"></a>
<h4 class="subheading">gnutls_strerror_name</h4>
<a name="gnutls_005fstrerror_005fname"></a><dl>
<dt><a name="index-gnutls_005fstrerror_005fname"></a>Function: <em>const char *</em> <strong>gnutls_strerror_name</strong> <em>(int <var>error</var>)</em></dt>
<dd><p><var>error</var>: is an error returned by a gnutls function.
</p>
<p>Return the GnuTLS error code define as a string.  For example,
gnutls_strerror_name (GNUTLS_E_DH_PRIME_UNACCEPTABLE) will return
the string &quot;GNUTLS_E_DH_PRIME_UNACCEPTABLE&quot;.
</p>
<p><strong>Returns:</strong> A string corresponding to the symbol name of the error
code.
</p>
<p><strong>Since:</strong> 2.6.0
</p></dd></dl>

<a name="gnutls_005fsupplemental_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_supplemental_get_name</h4>
<a name="gnutls_005fsupplemental_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fsupplemental_005fget_005fname"></a>Function: <em>const char     *</em> <strong>gnutls_supplemental_get_name</strong> <em>(gnutls_supplemental_data_format_type_t       <var>type</var>)</em></dt>
<dd><p><var>type</var>: is a supplemental data format type
</p>
<p>Convert a <code>gnutls_supplemental_data_format_type_t</code>  value to a
string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified
supplemental data format type, or <code>NULL</code>  for unknown types.
</p></dd></dl>

<a name="gnutls_005fsupplemental_005frecv-1"></a>
<h4 class="subheading">gnutls_supplemental_recv</h4>
<a name="gnutls_005fsupplemental_005frecv"></a><dl>
<dt><a name="index-gnutls_005fsupplemental_005frecv"></a>Function: <em>void</em> <strong>gnutls_supplemental_recv</strong> <em>(gnutls_session_t <var>session</var>, unsigned <var>do_recv_supplemental</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>do_recv_supplemental</var>: non-zero in order to expect supplemental data
</p>
<p>This function is to be called by an extension handler to
instruct gnutls to attempt to receive supplemental data
during the handshake process.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fsupplemental_005fregister-1"></a>
<h4 class="subheading">gnutls_supplemental_register</h4>
<a name="gnutls_005fsupplemental_005fregister"></a><dl>
<dt><a name="index-gnutls_005fsupplemental_005fregister"></a>Function: <em>int</em> <strong>gnutls_supplemental_register</strong> <em>(const char * <var>name</var>, gnutls_supplemental_data_format_type_t <var>type</var>, gnutls_supp_recv_func <var>recv_func</var>, gnutls_supp_send_func <var>send_func</var>)</em></dt>
<dd><p><var>name</var>: the name of the supplemental data to register
</p>
<p><var>type</var>: the type of the supplemental data format
</p>
<p><var>recv_func</var>: the function to receive the data
</p>
<p><var>send_func</var>: the function to send the data
</p>
<p>This function will register a new supplemental data type (rfc4680).
The registered data will remain until <code>gnutls_global_deinit()</code> 
is called. The provided  <code>type</code> must be an unassigned type in
<code>gnutls_supplemental_data_format_type_t</code> . If the type is already
registered or handled by GnuTLS internally <code>GNUTLS_E_ALREADY_REGISTERED</code> 
will be returned.
</p>
<p>This function is not thread safe.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fsupplemental_005fsend-1"></a>
<h4 class="subheading">gnutls_supplemental_send</h4>
<a name="gnutls_005fsupplemental_005fsend"></a><dl>
<dt><a name="index-gnutls_005fsupplemental_005fsend"></a>Function: <em>void</em> <strong>gnutls_supplemental_send</strong> <em>(gnutls_session_t <var>session</var>, unsigned <var>do_send_supplemental</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>do_send_supplemental</var>: &ndash; undescribed &ndash;
</p>
<p>This function is to be called by an extension handler to
instruct gnutls to send supplemental data during the handshake process.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fsystem_005frecv_005ftimeout-1"></a>
<h4 class="subheading">gnutls_system_recv_timeout</h4>
<a name="gnutls_005fsystem_005frecv_005ftimeout"></a><dl>
<dt><a name="index-gnutls_005fsystem_005frecv_005ftimeout"></a>Function: <em>int</em> <strong>gnutls_system_recv_timeout</strong> <em>(gnutls_transport_ptr_t <var>ptr</var>, unsigned int <var>ms</var>)</em></dt>
<dd><p><var>ptr</var>: A gnutls_transport_ptr_t pointer
</p>
<p><var>ms</var>: The number of milliseconds to wait.
</p>
<p>Wait for data to be received from the provided socket ( <code>ptr</code> ) within a
timeout period in milliseconds, using <code>select()</code>  on the provided  <code>ptr</code> .
</p>
<p>This function is provided as a helper for constructing custom
callbacks for <code>gnutls_transport_set_pull_timeout_function()</code> ,
which can be used if you rely on socket file descriptors.
</p>
<p>Returns -1 on error, 0 on timeout, positive value if data are available for reading.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005ftdb_005fdeinit-1"></a>
<h4 class="subheading">gnutls_tdb_deinit</h4>
<a name="gnutls_005ftdb_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005ftdb_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_tdb_deinit</strong> <em>(gnutls_tdb_t <var>tdb</var>)</em></dt>
<dd><p><var>tdb</var>: The structure to be deinitialized
</p>
<p>This function will deinitialize a public key trust storage structure.
</p></dd></dl>

<a name="gnutls_005ftdb_005finit-1"></a>
<h4 class="subheading">gnutls_tdb_init</h4>
<a name="gnutls_005ftdb_005finit"></a><dl>
<dt><a name="index-gnutls_005ftdb_005finit"></a>Function: <em>int</em> <strong>gnutls_tdb_init</strong> <em>(gnutls_tdb_t * <var>tdb</var>)</em></dt>
<dd><p><var>tdb</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize a public key trust storage structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005ftdb_005fset_005fstore_005fcommitment_005ffunc-1"></a>
<h4 class="subheading">gnutls_tdb_set_store_commitment_func</h4>
<a name="gnutls_005ftdb_005fset_005fstore_005fcommitment_005ffunc"></a><dl>
<dt><a name="index-gnutls_005ftdb_005fset_005fstore_005fcommitment_005ffunc"></a>Function: <em>void</em> <strong>gnutls_tdb_set_store_commitment_func</strong> <em>(gnutls_tdb_t <var>tdb</var>, gnutls_tdb_store_commitment_func        <var>cstore</var>)</em></dt>
<dd><p><var>tdb</var>: The trust storage
</p>
<p><var>cstore</var>: The commitment storage function
</p>
<p>This function will associate a commitment (hash) storage function with the
trust storage structure. The function is of the following form.
</p>
<p>int gnutls_tdb_store_commitment_func(const char* db_name, const char* host,
const char* service, time_t expiration,
gnutls_digest_algorithm_t, const gnutls_datum_t* hash);
</p>
<p>The  <code>db_name</code> should be used to pass any private data to this function.
</p></dd></dl>

<a name="gnutls_005ftdb_005fset_005fstore_005ffunc-1"></a>
<h4 class="subheading">gnutls_tdb_set_store_func</h4>
<a name="gnutls_005ftdb_005fset_005fstore_005ffunc"></a><dl>
<dt><a name="index-gnutls_005ftdb_005fset_005fstore_005ffunc"></a>Function: <em>void</em> <strong>gnutls_tdb_set_store_func</strong> <em>(gnutls_tdb_t <var>tdb</var>, gnutls_tdb_store_func <var>store</var>)</em></dt>
<dd><p><var>tdb</var>: The trust storage
</p>
<p><var>store</var>: The storage function
</p>
<p>This function will associate a storage function with the
trust storage structure. The function is of the following form.
</p>
<p>int gnutls_tdb_store_func(const char* db_name, const char* host,
const char* service, time_t expiration,
const gnutls_datum_t* pubkey);
</p>
<p>The  <code>db_name</code> should be used to pass any private data to this function.
</p></dd></dl>

<a name="gnutls_005ftdb_005fset_005fverify_005ffunc-1"></a>
<h4 class="subheading">gnutls_tdb_set_verify_func</h4>
<a name="gnutls_005ftdb_005fset_005fverify_005ffunc"></a><dl>
<dt><a name="index-gnutls_005ftdb_005fset_005fverify_005ffunc"></a>Function: <em>void</em> <strong>gnutls_tdb_set_verify_func</strong> <em>(gnutls_tdb_t <var>tdb</var>, gnutls_tdb_verify_func <var>verify</var>)</em></dt>
<dd><p><var>tdb</var>: The trust storage
</p>
<p><var>verify</var>: The verification function
</p>
<p>This function will associate a retrieval function with the
trust storage structure. The function is of the following form.
</p>
<p>int gnutls_tdb_verify_func(const char* db_name, const char* host,
const char* service, const gnutls_datum_t* pubkey);
</p>
<p>The verify function should return zero on a match, <code>GNUTLS_E_CERTIFICATE_KEY_MISMATCH</code> 
if there is a mismatch and any other negative error code otherwise.
</p>
<p>The  <code>db_name</code> should be used to pass any private data to this function.
</p></dd></dl>

<a name="gnutls_005ftransport_005fget_005fint-1"></a>
<h4 class="subheading">gnutls_transport_get_int</h4>
<a name="gnutls_005ftransport_005fget_005fint"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fget_005fint"></a>Function: <em>int</em> <strong>gnutls_transport_get_int</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Used to get the first argument of the transport function (like
PUSH and PULL).  This must have been set using
<code>gnutls_transport_set_int()</code> .
</p>
<p><strong>Returns:</strong> The first argument of the transport function.
</p>
<p><strong>Since:</strong> 3.1.9
</p></dd></dl>

<a name="gnutls_005ftransport_005fget_005fint2-1"></a>
<h4 class="subheading">gnutls_transport_get_int2</h4>
<a name="gnutls_005ftransport_005fget_005fint2"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fget_005fint2"></a>Function: <em>void</em> <strong>gnutls_transport_get_int2</strong> <em>(gnutls_session_t <var>session</var>, int * <var>recv_int</var>, int * <var>send_int</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>recv_int</var>: will hold the value for the pull function
</p>
<p><var>send_int</var>: will hold the value for the push function
</p>
<p>Used to get the arguments of the transport functions (like PUSH
and PULL).  These should have been set using
<code>gnutls_transport_set_int2()</code> .
</p>
<p><strong>Since:</strong> 3.1.9
</p></dd></dl>

<a name="gnutls_005ftransport_005fget_005fptr-1"></a>
<h4 class="subheading">gnutls_transport_get_ptr</h4>
<a name="gnutls_005ftransport_005fget_005fptr"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fget_005fptr"></a>Function: <em>gnutls_transport_ptr_t</em> <strong>gnutls_transport_get_ptr</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Used to get the first argument of the transport function (like
PUSH and PULL).  This must have been set using
<code>gnutls_transport_set_ptr()</code> .
</p>
<p><strong>Returns:</strong> The first argument of the transport function.
</p></dd></dl>

<a name="gnutls_005ftransport_005fget_005fptr2-1"></a>
<h4 class="subheading">gnutls_transport_get_ptr2</h4>
<a name="gnutls_005ftransport_005fget_005fptr2"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fget_005fptr2"></a>Function: <em>void</em> <strong>gnutls_transport_get_ptr2</strong> <em>(gnutls_session_t <var>session</var>, gnutls_transport_ptr_t * <var>recv_ptr</var>, gnutls_transport_ptr_t * <var>send_ptr</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>recv_ptr</var>: will hold the value for the pull function
</p>
<p><var>send_ptr</var>: will hold the value for the push function
</p>
<p>Used to get the arguments of the transport functions (like PUSH
and PULL).  These should have been set using
<code>gnutls_transport_set_ptr2()</code> .
</p></dd></dl>

<a name="gnutls_005ftransport_005fset_005ferrno-1"></a>
<h4 class="subheading">gnutls_transport_set_errno</h4>
<a name="gnutls_005ftransport_005fset_005ferrno"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fset_005ferrno-1"></a>Function: <em>void</em> <strong>gnutls_transport_set_errno</strong> <em>(gnutls_session_t <var>session</var>, int <var>err</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>err</var>: error value to store in session-specific errno variable.
</p>
<p>Store  <code>err</code> in the session-specific errno variable.  Useful values
for  <code>err</code> are EINTR, EAGAIN and EMSGSIZE, other values are treated will be
treated as real errors in the push/pull function.
</p>
<p>This function is useful in replacement push and pull functions set by
<code>gnutls_transport_set_push_function()</code>  and
<code>gnutls_transport_set_pull_function()</code>  under Windows, where the
replacements may not have access to the same  <code>errno</code> variable that is used by GnuTLS (e.g., the application is linked to
msvcr71.dll and gnutls is linked to msvcrt.dll).
</p></dd></dl>

<a name="gnutls_005ftransport_005fset_005ferrno_005ffunction-1"></a>
<h4 class="subheading">gnutls_transport_set_errno_function</h4>
<a name="gnutls_005ftransport_005fset_005ferrno_005ffunction"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fset_005ferrno_005ffunction"></a>Function: <em>void</em> <strong>gnutls_transport_set_errno_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_errno_func <var>errno_func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>errno_func</var>: a callback function similar to <code>write()</code> 
</p>
<p>This is the function where you set a function to retrieve errno
after a failed push or pull operation.
</p>
<p><code>errno_func</code> is of the form,
int (*gnutls_errno_func)(gnutls_transport_ptr_t);
and should return the errno.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005ftransport_005fset_005fint-1"></a>
<h4 class="subheading">gnutls_transport_set_int</h4>
<a name="gnutls_005ftransport_005fset_005fint"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fint"></a>Function: <em>void</em> <strong>gnutls_transport_set_int</strong> <em>(gnutls_session_t <var>session</var>, int <var>i</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>i</var>: is the value.
</p>
<p>Used to set the first argument of the transport function (for push
and pull callbacks) for berkeley style sockets.
</p>
<p><strong>Since:</strong> 3.1.9
</p></dd></dl>

<a name="gnutls_005ftransport_005fset_005fint2-1"></a>
<h4 class="subheading">gnutls_transport_set_int2</h4>
<a name="gnutls_005ftransport_005fset_005fint2"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fint2"></a>Function: <em>void</em> <strong>gnutls_transport_set_int2</strong> <em>(gnutls_session_t <var>session</var>, int <var>recv_int</var>, int <var>send_int</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>recv_int</var>: is the value for the pull function
</p>
<p><var>send_int</var>: is the value for the push function
</p>
<p>Used to set the first argument of the transport function (for push
and pull callbacks), when using the berkeley style sockets. 
With this function you can set two different
pointers for receiving and sending.
</p>
<p><strong>Since:</strong> 3.1.9
</p></dd></dl>

<a name="gnutls_005ftransport_005fset_005fptr-1"></a>
<h4 class="subheading">gnutls_transport_set_ptr</h4>
<a name="gnutls_005ftransport_005fset_005fptr"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fptr"></a>Function: <em>void</em> <strong>gnutls_transport_set_ptr</strong> <em>(gnutls_session_t <var>session</var>, gnutls_transport_ptr_t <var>ptr</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>ptr</var>: is the value.
</p>
<p>Used to set the first argument of the transport function (for push
and pull callbacks). In berkeley style sockets this function will set the
connection descriptor.
</p></dd></dl>

<a name="gnutls_005ftransport_005fset_005fptr2-1"></a>
<h4 class="subheading">gnutls_transport_set_ptr2</h4>
<a name="gnutls_005ftransport_005fset_005fptr2"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fptr2"></a>Function: <em>void</em> <strong>gnutls_transport_set_ptr2</strong> <em>(gnutls_session_t <var>session</var>, gnutls_transport_ptr_t <var>recv_ptr</var>, gnutls_transport_ptr_t <var>send_ptr</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>recv_ptr</var>: is the value for the pull function
</p>
<p><var>send_ptr</var>: is the value for the push function
</p>
<p>Used to set the first argument of the transport function (for push
and pull callbacks). In berkeley style sockets this function will set the
connection descriptor.  With this function you can use two different
pointers for receiving and sending.
</p></dd></dl>

<a name="gnutls_005ftransport_005fset_005fpull_005ffunction-1"></a>
<h4 class="subheading">gnutls_transport_set_pull_function</h4>
<a name="gnutls_005ftransport_005fset_005fpull_005ffunction"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fpull_005ffunction-1"></a>Function: <em>void</em> <strong>gnutls_transport_set_pull_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_pull_func <var>pull_func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>pull_func</var>: a callback function similar to <code>read()</code> 
</p>
<p>This is the function where you set a function for gnutls to receive
data.  Normally, if you use berkeley style sockets, do not need to
use this function since the default recv(2) will probably be ok.
The callback should return 0 on connection termination, a positive
number indicating the number of bytes received, and -1 on error.
</p>
<p><code>gnutls_pull_func</code> is of the form,
ssize_t (*gnutls_pull_func)(gnutls_transport_ptr_t, void*, size_t);
</p></dd></dl>

<a name="gnutls_005ftransport_005fset_005fpull_005ftimeout_005ffunction-1"></a>
<h4 class="subheading">gnutls_transport_set_pull_timeout_function</h4>
<a name="gnutls_005ftransport_005fset_005fpull_005ftimeout_005ffunction"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fpull_005ftimeout_005ffunction-2"></a>Function: <em>void</em> <strong>gnutls_transport_set_pull_timeout_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_pull_timeout_func <var>func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>func</var>: a callback function
</p>
<p>This is the function where you set a function for gnutls to know
whether data are ready to be received. It should wait for data a
given time frame in milliseconds. The callback should return 0 on 
timeout, a positive number if data can be received, and -1 on error.
You&rsquo;ll need to override this function if <code>select()</code>  is not suitable
for the provided transport calls.
</p>
<p>As with <code>select()</code> , if the timeout value is zero the callback should return
zero if no data are immediately available.
</p>
<p><code>gnutls_pull_timeout_func</code> is of the form,
int (*gnutls_pull_timeout_func)(gnutls_transport_ptr_t, unsigned int ms);
</p>
<p>This callback is necessary when <code>gnutls_handshake_set_timeout()</code>  or 
<code>gnutls_record_set_timeout()</code>  are set. It will not be used when 
non-blocking sockets are in use. That is, this function will
not operate when <code>GNUTLS_NONBLOCK</code>  is specified in <code>gnutls_init()</code> , 
or a custom pull function is registered without updating the 
pull timeout function.
</p>
<p>The helper function <code>gnutls_system_recv_timeout()</code>  is provided to
simplify writing callbacks. 
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005ftransport_005fset_005fpush_005ffunction-1"></a>
<h4 class="subheading">gnutls_transport_set_push_function</h4>
<a name="gnutls_005ftransport_005fset_005fpush_005ffunction"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fpush_005ffunction-1"></a>Function: <em>void</em> <strong>gnutls_transport_set_push_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_push_func <var>push_func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>push_func</var>: a callback function similar to <code>write()</code> 
</p>
<p>This is the function where you set a push function for gnutls to
use in order to send data.  If you are going to use berkeley style
sockets, you do not need to use this function since the default
send(2) will probably be ok.  Otherwise you should specify this
function for gnutls to be able to send data.
The callback should return a positive number indicating the
bytes sent, and -1 on error.
</p>
<p><code>push_func</code> is of the form,
ssize_t (*gnutls_push_func)(gnutls_transport_ptr_t, const void*, size_t);
</p></dd></dl>

<a name="gnutls_005ftransport_005fset_005fvec_005fpush_005ffunction-1"></a>
<h4 class="subheading">gnutls_transport_set_vec_push_function</h4>
<a name="gnutls_005ftransport_005fset_005fvec_005fpush_005ffunction"></a><dl>
<dt><a name="index-gnutls_005ftransport_005fset_005fvec_005fpush_005ffunction-1"></a>Function: <em>void</em> <strong>gnutls_transport_set_vec_push_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_vec_push_func <var>vec_func</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>vec_func</var>: a callback function similar to <code>writev()</code> 
</p>
<p>Using this function you can override the default writev(2)
function for gnutls to send data. Setting this callback 
instead of <code>gnutls_transport_set_push_function()</code>  is recommended
since it introduces less overhead in the TLS handshake process.
</p>
<p><code>vec_func</code> is of the form,
ssize_t (*gnutls_vec_push_func) (gnutls_transport_ptr_t, const giovec_t * iov, int iovcnt);
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005furl_005fis_005fsupported-1"></a>
<h4 class="subheading">gnutls_url_is_supported</h4>
<a name="gnutls_005furl_005fis_005fsupported"></a><dl>
<dt><a name="index-gnutls_005furl_005fis_005fsupported-1"></a>Function: <em>int</em> <strong>gnutls_url_is_supported</strong> <em>(const char * <var>url</var>)</em></dt>
<dd><p><var>url</var>: A PKCS 11 url
</p>
<p>Check whether url is supported.  Depending on the system libraries
GnuTLS may support pkcs11 or tpmkey URLs.
</p>
<p><strong>Returns:</strong> return non-zero if the given URL is supported, and zero if
it is not known.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fverify_005fstored_005fpubkey-1"></a>
<h4 class="subheading">gnutls_verify_stored_pubkey</h4>
<a name="gnutls_005fverify_005fstored_005fpubkey"></a><dl>
<dt><a name="index-gnutls_005fverify_005fstored_005fpubkey-1"></a>Function: <em>int</em> <strong>gnutls_verify_stored_pubkey</strong> <em>(const char * <var>db_name</var>, gnutls_tdb_t <var>tdb</var>, const char * <var>host</var>, const char * <var>service</var>, gnutls_certificate_type_t <var>cert_type</var>, const gnutls_datum_t * <var>cert</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>db_name</var>: A file specifying the stored keys (use NULL for the default)
</p>
<p><var>tdb</var>: A storage structure or NULL to use the default
</p>
<p><var>host</var>: The peer&rsquo;s name
</p>
<p><var>service</var>: non-NULL if this key is specific to a service (e.g. http)
</p>
<p><var>cert_type</var>: The type of the certificate
</p>
<p><var>cert</var>: The raw (der) data of the certificate
</p>
<p><var>flags</var>: should be 0.
</p>
<p>This function will try to verify the provided (raw or DER-encoded) certificate 
using a list of stored public keys.  The  <code>service</code> field if non-NULL should
be a port number.
</p>
<p>The  <code>retrieve</code> variable if non-null specifies a custom backend for
the retrieval of entries. If it is NULL then the
default file backend will be used. In POSIX-like systems the
file backend uses the $HOME/.gnutls/known_hosts file.
</p>
<p>Note that if the custom storage backend is provided the
retrieval function should return <code>GNUTLS_E_CERTIFICATE_KEY_MISMATCH</code> 
if the host/service pair is found but key doesn&rsquo;t match,
<code>GNUTLS_E_NO_CERTIFICATE_FOUND</code>  if no such host/service with
the given key is found, and 0 if it was found. The storage
function should return 0 on success.
</p>
<p><strong>Returns:</strong> If no associated public key is found
then <code>GNUTLS_E_NO_CERTIFICATE_FOUND</code>  will be returned. If a key
is found but does not match <code>GNUTLS_E_CERTIFICATE_KEY_MISMATCH</code> 
is returned. On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, 
or a negative error value on other errors.
</p>
<p><strong>Since:</strong> 3.0.13
</p></dd></dl>


<hr>
<a name="Datagram-TLS-API"></a>
<div class="header">
<p>
Next: <a href="#X509-certificate-API" accesskey="n" rel="next">X509 certificate API</a>, Previous: <a href="#Core-TLS-API" accesskey="p" rel="prev">Core TLS API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Datagram-TLS-API-1"></a>
<h3 class="section">E.2 Datagram TLS API</h3>

<p>The prototypes for the following functions lie in
<samp>gnutls/dtls.h</samp>.
</p>

<a name="gnutls_005fdtls_005fcookie_005fsend-1"></a>
<h4 class="subheading">gnutls_dtls_cookie_send</h4>
<a name="gnutls_005fdtls_005fcookie_005fsend"></a><dl>
<dt><a name="index-gnutls_005fdtls_005fcookie_005fsend"></a>Function: <em>int</em> <strong>gnutls_dtls_cookie_send</strong> <em>(gnutls_datum_t * <var>key</var>, void * <var>client_data</var>, size_t <var>client_data_size</var>, gnutls_dtls_prestate_st * <var>prestate</var>, gnutls_transport_ptr_t <var>ptr</var>, gnutls_push_func <var>push_func</var>)</em></dt>
<dd><p><var>key</var>: is a random key to be used at cookie generation
</p>
<p><var>client_data</var>: contains data identifying the client (i.e. address)
</p>
<p><var>client_data_size</var>: The size of client&rsquo;s data
</p>
<p><var>prestate</var>: The previous cookie returned by <code>gnutls_dtls_cookie_verify()</code> 
</p>
<p><var>ptr</var>: A transport pointer to be used by  <code>push_func</code> 
</p>
<p><var>push_func</var>: A function that will be used to reply
</p>
<p>This function can be used to prevent denial of service
attacks to a DTLS server by requiring the client to
reply using a cookie sent by this function. That way
it can be ensured that a client we allocated resources
for (i.e. <code>gnutls_session_t</code> ) is the one that the 
original incoming packet was originated from.
</p>
<p>This function must be called at the first incoming packet,
prior to allocating any resources and must be succeeded
by <code>gnutls_dtls_cookie_verify()</code> .
</p>
<p><strong>Returns:</strong> the number of bytes sent, or a negative error code.  
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fdtls_005fcookie_005fverify-1"></a>
<h4 class="subheading">gnutls_dtls_cookie_verify</h4>
<a name="gnutls_005fdtls_005fcookie_005fverify"></a><dl>
<dt><a name="index-gnutls_005fdtls_005fcookie_005fverify"></a>Function: <em>int</em> <strong>gnutls_dtls_cookie_verify</strong> <em>(gnutls_datum_t * <var>key</var>, void * <var>client_data</var>, size_t <var>client_data_size</var>, void * <var>_msg</var>, size_t <var>msg_size</var>, gnutls_dtls_prestate_st * <var>prestate</var>)</em></dt>
<dd><p><var>key</var>: is a random key to be used at cookie generation
</p>
<p><var>client_data</var>: contains data identifying the client (i.e. address)
</p>
<p><var>client_data_size</var>: The size of client&rsquo;s data
</p>
<p><var>_msg</var>: An incoming message that initiates a connection.
</p>
<p><var>msg_size</var>: The size of the message.
</p>
<p><var>prestate</var>: The cookie of this client.
</p>
<p>This function will verify the received message for
a valid cookie. If a valid cookie is returned then
it should be associated with the session using
<code>gnutls_dtls_prestate_set()</code> ;
</p>
<p>This function must be called after <code>gnutls_dtls_cookie_send()</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.  
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fdtls_005fget_005fdata_005fmtu-1"></a>
<h4 class="subheading">gnutls_dtls_get_data_mtu</h4>
<a name="gnutls_005fdtls_005fget_005fdata_005fmtu"></a><dl>
<dt><a name="index-gnutls_005fdtls_005fget_005fdata_005fmtu"></a>Function: <em>unsigned int</em> <strong>gnutls_dtls_get_data_mtu</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function will return the actual maximum transfer unit for
application data. I.e. DTLS headers are subtracted from the
actual MTU which is set using <code>gnutls_dtls_set_mtu()</code> .
</p>
<p><strong>Returns:</strong> the maximum allowed transfer unit.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fdtls_005fget_005fmtu-1"></a>
<h4 class="subheading">gnutls_dtls_get_mtu</h4>
<a name="gnutls_005fdtls_005fget_005fmtu"></a><dl>
<dt><a name="index-gnutls_005fdtls_005fget_005fmtu"></a>Function: <em>unsigned int</em> <strong>gnutls_dtls_get_mtu</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function will return the MTU size as set with
<code>gnutls_dtls_set_mtu()</code> . This is not the actual MTU
of data you can transmit. Use <code>gnutls_dtls_get_data_mtu()</code> 
for that reason.
</p>
<p><strong>Returns:</strong> the set maximum transfer unit.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fdtls_005fget_005ftimeout-1"></a>
<h4 class="subheading">gnutls_dtls_get_timeout</h4>
<a name="gnutls_005fdtls_005fget_005ftimeout"></a><dl>
<dt><a name="index-gnutls_005fdtls_005fget_005ftimeout-1"></a>Function: <em>unsigned int</em> <strong>gnutls_dtls_get_timeout</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>This function will return the milliseconds remaining
for a retransmission of the previously sent handshake
message. This function is useful when DTLS is used in
non-blocking mode, to estimate when to call <code>gnutls_handshake()</code> 
if no packets have been received.
</p>
<p><strong>Returns:</strong> the remaining time in milliseconds.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fdtls_005fprestate_005fset-1"></a>
<h4 class="subheading">gnutls_dtls_prestate_set</h4>
<a name="gnutls_005fdtls_005fprestate_005fset"></a><dl>
<dt><a name="index-gnutls_005fdtls_005fprestate_005fset"></a>Function: <em>void</em> <strong>gnutls_dtls_prestate_set</strong> <em>(gnutls_session_t <var>session</var>, gnutls_dtls_prestate_st * <var>prestate</var>)</em></dt>
<dd><p><var>session</var>: a new session
</p>
<p><var>prestate</var>: contains the client&rsquo;s prestate
</p>
<p>This function will associate the prestate acquired by
the cookie authentication with the client, with the newly 
established session.
</p>
<p>This functions must be called after a successful <code>gnutls_dtls_cookie_verify()</code> 
and should be succeeded by the actual DTLS handshake using <code>gnutls_handshake()</code> .
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fdtls_005fset_005fdata_005fmtu-1"></a>
<h4 class="subheading">gnutls_dtls_set_data_mtu</h4>
<a name="gnutls_005fdtls_005fset_005fdata_005fmtu"></a><dl>
<dt><a name="index-gnutls_005fdtls_005fset_005fdata_005fmtu"></a>Function: <em>int</em> <strong>gnutls_dtls_set_data_mtu</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>mtu</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>mtu</var>: The maximum unencrypted transfer unit of the session
</p>
<p>This function will set the maximum size of the *unencrypted* records
which will be sent over a DTLS session. It is equivalent to calculating
the DTLS packet overhead with the current encryption parameters, and
calling <code>gnutls_dtls_set_mtu()</code>  with that value. In particular, this means
that you may need to call this function again after any negotiation or
renegotiation, in order to ensure that the MTU is still sufficient to
account for the new protocol overhead.
</p>
<p>In most cases you only need to call <code>gnutls_dtls_set_mtu()</code>  with
the maximum MTU of your transport layer.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p>
<p><strong>Since:</strong> 3.1
</p></dd></dl>

<a name="gnutls_005fdtls_005fset_005fmtu-1"></a>
<h4 class="subheading">gnutls_dtls_set_mtu</h4>
<a name="gnutls_005fdtls_005fset_005fmtu"></a><dl>
<dt><a name="index-gnutls_005fdtls_005fset_005fmtu"></a>Function: <em>void</em> <strong>gnutls_dtls_set_mtu</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>mtu</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>mtu</var>: The maximum transfer unit of the transport
</p>
<p>This function will set the maximum transfer unit of the transport
that DTLS packets are sent over. Note that this should exclude
the IP (or IPv6) and UDP headers. So for DTLS over IPv6 on an
Ethenet device with MTU 1500, the DTLS MTU set with this function
would be 1500 - 40 (IPV6 header) - 8 (UDP header) = 1452.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fdtls_005fset_005ftimeouts-1"></a>
<h4 class="subheading">gnutls_dtls_set_timeouts</h4>
<a name="gnutls_005fdtls_005fset_005ftimeouts"></a><dl>
<dt><a name="index-gnutls_005fdtls_005fset_005ftimeouts"></a>Function: <em>void</em> <strong>gnutls_dtls_set_timeouts</strong> <em>(gnutls_session_t <var>session</var>, unsigned int <var>retrans_timeout</var>, unsigned int <var>total_timeout</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p><var>retrans_timeout</var>: The time at which a retransmission will occur in milliseconds
</p>
<p><var>total_timeout</var>: The time at which the connection will be aborted, in milliseconds.
</p>
<p>This function will set the timeouts required for the DTLS handshake
protocol. The retransmission timeout is the time after which a
message from the peer is not received, the previous messages will
be retransmitted. The total timeout is the time after which the
handshake will be aborted with <code>GNUTLS_E_TIMEDOUT</code> .
</p>
<p>The DTLS protocol recommends the values of 1 sec and 60 seconds
respectively, and these are the default values.
</p>
<p>To disable retransmissions set a  <code>retrans_timeout</code> larger than the  <code>total_timeout</code> .
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005frecord_005fget_005fdiscarded-1"></a>
<h4 class="subheading">gnutls_record_get_discarded</h4>
<a name="gnutls_005frecord_005fget_005fdiscarded"></a><dl>
<dt><a name="index-gnutls_005frecord_005fget_005fdiscarded"></a>Function: <em>unsigned int</em> <strong>gnutls_record_get_discarded</strong> <em>(gnutls_session_t <var>session</var>)</em></dt>
<dd><p><var>session</var>: is a <code>gnutls_session_t</code>  type.
</p>
<p>Returns the number of discarded packets in a
DTLS connection.
</p>
<p><strong>Returns:</strong> The number of discarded packets.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>


<hr>
<a name="X509-certificate-API"></a>
<div class="header">
<p>
Next: <a href="#PKCS-7-API" accesskey="n" rel="next">PKCS 7 API</a>, Previous: <a href="#Datagram-TLS-API" accesskey="p" rel="prev">Datagram TLS API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="X_002e509-certificate-API"></a>
<h3 class="section">E.3 <acronym>X.509</acronym> certificate API</h3>
<a name="index-X_002e509-Functions"></a>

<p>The following functions are to be used for <acronym>X.509</acronym> certificate handling.
Their prototypes lie in <samp>gnutls/x509.h</samp>.
</p>

<a name="gnutls_005fcertificate_005fget_005ftrust_005flist-1"></a>
<h4 class="subheading">gnutls_certificate_get_trust_list</h4>
<a name="gnutls_005fcertificate_005fget_005ftrust_005flist"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fget_005ftrust_005flist"></a>Function: <em>void</em> <strong>gnutls_certificate_get_trust_list</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, gnutls_x509_trust_list_t * <var>tlist</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>tlist</var>: Location where to store the trust list.
</p>
<p>Obtains the list of trusted certificates stored in  <code>res</code> and writes a
pointer to it to the location  <code>tlist</code> . The pointer will point to memory
internal to  <code>res</code> , and must not be deinitialized. It will be automatically
deallocated when the  <code>res</code> structure is deinitialized.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005ftrust_005flist-1"></a>
<h4 class="subheading">gnutls_certificate_set_trust_list</h4>
<a name="gnutls_005fcertificate_005fset_005ftrust_005flist"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005ftrust_005flist"></a>Function: <em>void</em> <strong>gnutls_certificate_set_trust_list</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, gnutls_x509_trust_list_t <var>tlist</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>tlist</var>: is a <code>gnutls_x509_trust_list_t</code>  type
</p>
<p><var>flags</var>: must be zero
</p>
<p>This function sets a trust list in the gnutls_certificate_credentials_t type. 
</p>
<p>Note that the  <code>tlist</code> will become part of the credentials 
structure and must not be deallocated. It will be automatically deallocated 
when the  <code>res</code> structure is deinitialized.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p>
<p><strong>Since:</strong> 3.2.2
</p></dd></dl>

<a name="gnutls_005fpkcs8_005finfo-1"></a>
<h4 class="subheading">gnutls_pkcs8_info</h4>
<a name="gnutls_005fpkcs8_005finfo"></a><dl>
<dt><a name="index-gnutls_005fpkcs8_005finfo"></a>Function: <em>int</em> <strong>gnutls_pkcs8_info</strong> <em>(const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int * <var>schema</var>, unsigned int * <var>cipher</var>, void * <var>salt</var>, unsigned int * <var>salt_size</var>, unsigned int * <var>iter_count</var>, char ** <var>oid</var>)</em></dt>
<dd><p><var>data</var>: Holds the PKCS <code>8</code>  data
</p>
<p><var>format</var>: the format of the PKCS <code>8</code>  data
</p>
<p><var>schema</var>: indicate the schema as one of <code>gnutls_pkcs_encrypt_flags_t</code> 
</p>
<p><var>cipher</var>: the cipher used as <code>gnutls_cipher_algorithm_t</code> 
</p>
<p><var>salt</var>: PBKDF2 salt (if non-NULL then  <code>salt_size</code> initially holds its size)
</p>
<p><var>salt_size</var>: PBKDF2 salt size
</p>
<p><var>iter_count</var>: PBKDF2 iteration count
</p>
<p><var>oid</var>: if non-NULL it will contain an allocated null-terminated variable with the OID
</p>
<p>This function will provide information on the algorithms used
in a particular PKCS <code>8</code>  structure. If the structure algorithms
are unknown the code <code>GNUTLS_E_UNKNOWN_CIPHER_TYPE</code>  will be returned,
and only  <code>oid</code> , will be set. That is,  <code>oid</code> will be set on encrypted PKCS <code>8</code> 
structures whether supported or not. It must be deinitialized using <code>gnutls_free()</code> .
The other variables are only set on supported structures.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_INVALID_REQUEST</code>  if the provided structure isn&rsquo;t encrypted,
<code>GNUTLS_E_UNKNOWN_CIPHER_TYPE</code>  if the structure&rsquo;s encryption isn&rsquo;t supported, or
another negative error code in case of a failure. Zero on success.
</p></dd></dl>

<a name="gnutls_005fpkcs_005fschema_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_pkcs_schema_get_name</h4>
<a name="gnutls_005fpkcs_005fschema_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fpkcs_005fschema_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_pkcs_schema_get_name</strong> <em>(unsigned int <var>schema</var>)</em></dt>
<dd><p><var>schema</var>: Holds the PKCS <code>12</code>  or PBES2 schema (<code>gnutls_pkcs_encrypt_flags_t</code> )
</p>
<p>This function will return a human readable description of the
PKCS12 or PBES2 schema.
</p>
<p><strong>Returns:</strong> a constrant string or <code>NULL</code>  on error.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fpkcs_005fschema_005fget_005foid-1"></a>
<h4 class="subheading">gnutls_pkcs_schema_get_oid</h4>
<a name="gnutls_005fpkcs_005fschema_005fget_005foid"></a><dl>
<dt><a name="index-gnutls_005fpkcs_005fschema_005fget_005foid"></a>Function: <em>const char *</em> <strong>gnutls_pkcs_schema_get_oid</strong> <em>(unsigned int <var>schema</var>)</em></dt>
<dd><p><var>schema</var>: Holds the PKCS <code>12</code>  or PBES2 schema (<code>gnutls_pkcs_encrypt_flags_t</code> )
</p>
<p>This function will return the object identifier of the
PKCS12 or PBES2 schema.
</p>
<p><strong>Returns:</strong> a constrant string or <code>NULL</code>  on error.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fsubject_005falt_005fnames_005fdeinit-1"></a>
<h4 class="subheading">gnutls_subject_alt_names_deinit</h4>
<a name="gnutls_005fsubject_005falt_005fnames_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fsubject_005falt_005fnames_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_subject_alt_names_deinit</strong> <em>(gnutls_subject_alt_names_t <var>sans</var>)</em></dt>
<dd><p><var>sans</var>: The alternative names
</p>
<p>This function will deinitialize an alternative names structure.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fsubject_005falt_005fnames_005fget-1"></a>
<h4 class="subheading">gnutls_subject_alt_names_get</h4>
<a name="gnutls_005fsubject_005falt_005fnames_005fget"></a><dl>
<dt><a name="index-gnutls_005fsubject_005falt_005fnames_005fget"></a>Function: <em>int</em> <strong>gnutls_subject_alt_names_get</strong> <em>(gnutls_subject_alt_names_t <var>sans</var>, unsigned int <var>seq</var>, unsigned int * <var>san_type</var>, gnutls_datum_t * <var>san</var>, gnutls_datum_t * <var>othername_oid</var>)</em></dt>
<dd><p><var>sans</var>: The alternative names
</p>
<p><var>seq</var>: The index of the name to get
</p>
<p><var>san_type</var>: Will hold the type of the name (of <code>gnutls_subject_alt_names_t</code> )
</p>
<p><var>san</var>: The alternative name data (should be treated as constant)
</p>
<p><var>othername_oid</var>: The object identifier if  <code>san_type</code> is <code>GNUTLS_SAN_OTHERNAME</code>  (should be treated as constant)
</p>
<p>This function will return a specific alternative name as stored in
the  <code>sans</code> type. The returned values should be treated as constant
and valid for the lifetime of  <code>sans</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the index is out of bounds, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fsubject_005falt_005fnames_005finit-1"></a>
<h4 class="subheading">gnutls_subject_alt_names_init</h4>
<a name="gnutls_005fsubject_005falt_005fnames_005finit"></a><dl>
<dt><a name="index-gnutls_005fsubject_005falt_005fnames_005finit"></a>Function: <em>int</em> <strong>gnutls_subject_alt_names_init</strong> <em>(gnutls_subject_alt_names_t * <var>sans</var>)</em></dt>
<dd><p><var>sans</var>: The alternative names
</p>
<p>This function will initialize an alternative names structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fsubject_005falt_005fnames_005fset-1"></a>
<h4 class="subheading">gnutls_subject_alt_names_set</h4>
<a name="gnutls_005fsubject_005falt_005fnames_005fset"></a><dl>
<dt><a name="index-gnutls_005fsubject_005falt_005fnames_005fset"></a>Function: <em>int</em> <strong>gnutls_subject_alt_names_set</strong> <em>(gnutls_subject_alt_names_t <var>sans</var>, unsigned int <var>san_type</var>, const gnutls_datum_t * <var>san</var>, const char * <var>othername_oid</var>)</em></dt>
<dd><p><var>sans</var>: The alternative names
</p>
<p><var>san_type</var>: The type of the name (of <code>gnutls_subject_alt_names_t</code> )
</p>
<p><var>san</var>: The alternative name data
</p>
<p><var>othername_oid</var>: The object identifier if  <code>san_type</code> is <code>GNUTLS_SAN_OTHERNAME</code> 
</p>
<p>This function will store the specified alternative name in
the  <code>sans</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0), otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005faia_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_aia_deinit</h4>
<a name="gnutls_005fx509_005faia_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005faia_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_aia_deinit</strong> <em>(gnutls_x509_aia_t <var>aia</var>)</em></dt>
<dd><p><var>aia</var>: The authority info access
</p>
<p>This function will deinitialize an authority info access type.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005faia_005fget-1"></a>
<h4 class="subheading">gnutls_x509_aia_get</h4>
<a name="gnutls_005fx509_005faia_005fget"></a><dl>
<dt><a name="index-gnutls_005fx509_005faia_005fget"></a>Function: <em>int</em> <strong>gnutls_x509_aia_get</strong> <em>(gnutls_x509_aia_t <var>aia</var>, unsigned int <var>seq</var>, gnutls_datum_t * <var>oid</var>, unsigned * <var>san_type</var>, gnutls_datum_t * <var>san</var>)</em></dt>
<dd><p><var>aia</var>: The authority info access
</p>
<p><var>seq</var>: specifies the sequence number of the access descriptor (0 for the first one, 1 for the second etc.)
</p>
<p><var>oid</var>: the type of available data; to be treated as constant.
</p>
<p><var>san_type</var>: Will hold the type of the name of <code>gnutls_subject_alt_names_t</code>  (may be null).
</p>
<p><var>san</var>: the access location name; to be treated as constant (may be null).
</p>
<p>This function reads from the Authority Information Access type.
</p>
<p>The  <code>seq</code> input parameter is used to indicate which member of the
sequence the caller is interested in.  The first member is 0, the
second member 1 and so on.  When the  <code>seq</code> value is out of bounds,
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p>
<p>Typically  <code>oid</code> is <code>GNUTLS_OID_AD_CAISSUERS</code>  or <code>GNUTLS_OID_AD_OCSP</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005faia_005finit-1"></a>
<h4 class="subheading">gnutls_x509_aia_init</h4>
<a name="gnutls_005fx509_005faia_005finit"></a><dl>
<dt><a name="index-gnutls_005fx509_005faia_005finit"></a>Function: <em>int</em> <strong>gnutls_x509_aia_init</strong> <em>(gnutls_x509_aia_t * <var>aia</var>)</em></dt>
<dd><p><var>aia</var>: The authority info access
</p>
<p>This function will initialize an authority info access type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005faia_005fset-1"></a>
<h4 class="subheading">gnutls_x509_aia_set</h4>
<a name="gnutls_005fx509_005faia_005fset"></a><dl>
<dt><a name="index-gnutls_005fx509_005faia_005fset"></a>Function: <em>int</em> <strong>gnutls_x509_aia_set</strong> <em>(gnutls_x509_aia_t <var>aia</var>, const char * <var>oid</var>, unsigned <var>san_type</var>, const gnutls_datum_t * <var>san</var>)</em></dt>
<dd><p><var>aia</var>: The authority info access
</p>
<p><var>oid</var>: the type of data.
</p>
<p><var>san_type</var>: The type of the name (of <code>gnutls_subject_alt_names_t</code> )
</p>
<p><var>san</var>: The alternative name data
</p>
<p>This function will store the specified alternative name in
the  <code>aia</code> type. 
</p>
<p>Typically the value for  <code>oid</code> should be <code>GNUTLS_OID_AD_OCSP</code> , or
<code>GNUTLS_OID_AD_CAISSUERS</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0), otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005faki_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_aki_deinit</h4>
<a name="gnutls_005fx509_005faki_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005faki_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_aki_deinit</strong> <em>(gnutls_x509_aki_t <var>aki</var>)</em></dt>
<dd><p><var>aki</var>: The authority key identifier type
</p>
<p>This function will deinitialize an authority key identifier.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005faki_005fget_005fcert_005fissuer-1"></a>
<h4 class="subheading">gnutls_x509_aki_get_cert_issuer</h4>
<a name="gnutls_005fx509_005faki_005fget_005fcert_005fissuer"></a><dl>
<dt><a name="index-gnutls_005fx509_005faki_005fget_005fcert_005fissuer"></a>Function: <em>int</em> <strong>gnutls_x509_aki_get_cert_issuer</strong> <em>(gnutls_x509_aki_t <var>aki</var>, unsigned int <var>seq</var>, unsigned int * <var>san_type</var>, gnutls_datum_t * <var>san</var>, gnutls_datum_t * <var>othername_oid</var>, gnutls_datum_t * <var>serial</var>)</em></dt>
<dd><p><var>aki</var>: The authority key ID
</p>
<p><var>seq</var>: The index of the name to get
</p>
<p><var>san_type</var>: Will hold the type of the name (of <code>gnutls_subject_alt_names_t</code> )
</p>
<p><var>san</var>: The alternative name data
</p>
<p><var>othername_oid</var>: The object identifier if  <code>san_type</code> is <code>GNUTLS_SAN_OTHERNAME</code> 
</p>
<p><var>serial</var>: The authorityCertSerialNumber number
</p>
<p>This function will return a specific authorityCertIssuer name as stored in
the  <code>aki</code> type, as well as the authorityCertSerialNumber. All the returned
values should be treated as constant, and may be set to <code>NULL</code>  when are not required.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the index is out of bounds, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005faki_005fget_005fid-1"></a>
<h4 class="subheading">gnutls_x509_aki_get_id</h4>
<a name="gnutls_005fx509_005faki_005fget_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005faki_005fget_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_aki_get_id</strong> <em>(gnutls_x509_aki_t <var>aki</var>, gnutls_datum_t * <var>id</var>)</em></dt>
<dd><p><var>aki</var>: The authority key ID
</p>
<p><var>id</var>: Will hold the identifier
</p>
<p>This function will return the key identifier as stored in
the  <code>aki</code> type. The identifier should be treated as constant.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the index is out of bounds, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005faki_005finit-1"></a>
<h4 class="subheading">gnutls_x509_aki_init</h4>
<a name="gnutls_005fx509_005faki_005finit"></a><dl>
<dt><a name="index-gnutls_005fx509_005faki_005finit"></a>Function: <em>int</em> <strong>gnutls_x509_aki_init</strong> <em>(gnutls_x509_aki_t * <var>aki</var>)</em></dt>
<dd><p><var>aki</var>: The authority key ID type
</p>
<p>This function will initialize an authority key ID.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005faki_005fset_005fcert_005fissuer-1"></a>
<h4 class="subheading">gnutls_x509_aki_set_cert_issuer</h4>
<a name="gnutls_005fx509_005faki_005fset_005fcert_005fissuer"></a><dl>
<dt><a name="index-gnutls_005fx509_005faki_005fset_005fcert_005fissuer"></a>Function: <em>int</em> <strong>gnutls_x509_aki_set_cert_issuer</strong> <em>(gnutls_x509_aki_t <var>aki</var>, unsigned int <var>san_type</var>, const gnutls_datum_t * <var>san</var>, const char * <var>othername_oid</var>, const gnutls_datum_t * <var>serial</var>)</em></dt>
<dd><p><var>aki</var>: The authority key ID
</p>
<p><var>san_type</var>: the type of the name (of <code>gnutls_subject_alt_names_t</code> ), may be null
</p>
<p><var>san</var>: The alternative name data
</p>
<p><var>othername_oid</var>: The object identifier if  <code>san_type</code> is <code>GNUTLS_SAN_OTHERNAME</code> 
</p>
<p><var>serial</var>: The authorityCertSerialNumber number (may be null)
</p>
<p>This function will set the authorityCertIssuer name and the authorityCertSerialNumber 
to be stored in the  <code>aki</code> type. When storing multiple names, the serial
should be set on the first call, and subsequent calls should use a <code>NULL</code>  serial.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005faki_005fset_005fid-1"></a>
<h4 class="subheading">gnutls_x509_aki_set_id</h4>
<a name="gnutls_005fx509_005faki_005fset_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005faki_005fset_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_aki_set_id</strong> <em>(gnutls_x509_aki_t <var>aki</var>, const gnutls_datum_t * <var>id</var>)</em></dt>
<dd><p><var>aki</var>: The authority key ID
</p>
<p><var>id</var>: the key identifier
</p>
<p>This function will set the keyIdentifier to be stored in the  <code>aki</code> type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fcheck_005fissuer-1"></a>
<h4 class="subheading">gnutls_x509_crl_check_issuer</h4>
<a name="gnutls_005fx509_005fcrl_005fcheck_005fissuer"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fcheck_005fissuer"></a>Function: <em>int</em> <strong>gnutls_x509_crl_check_issuer</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_t <var>issuer</var>)</em></dt>
<dd><p><var>crl</var>: is the CRL to be checked
</p>
<p><var>issuer</var>: is the certificate of a possible issuer
</p>
<p>This function will check if the given CRL was issued by the given
issuer certificate.  
</p>
<p><strong>Returns:</strong> true (1) if the given CRL was issued by the given issuer, 
and false (0) if not.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_crl_deinit</h4>
<a name="gnutls_005fx509_005fcrl_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_crl_deinit</strong> <em>(gnutls_x509_crl_t <var>crl</var>)</em></dt>
<dd><p><var>crl</var>: The data to be deinitialized
</p>
<p>This function will deinitialize a CRL structure.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fdist_005fpoints_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_crl_dist_points_deinit</h4>
<a name="gnutls_005fx509_005fcrl_005fdist_005fpoints_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fdist_005fpoints_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_crl_dist_points_deinit</strong> <em>(gnutls_x509_crl_dist_points_t <var>cdp</var>)</em></dt>
<dd><p><var>cdp</var>: The CRL distribution points
</p>
<p>This function will deinitialize a CRL distribution points type.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fdist_005fpoints_005fget-1"></a>
<h4 class="subheading">gnutls_x509_crl_dist_points_get</h4>
<a name="gnutls_005fx509_005fcrl_005fdist_005fpoints_005fget"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fdist_005fpoints_005fget"></a>Function: <em>int</em> <strong>gnutls_x509_crl_dist_points_get</strong> <em>(gnutls_x509_crl_dist_points_t <var>cdp</var>, unsigned int <var>seq</var>, unsigned int * <var>type</var>, gnutls_datum_t * <var>san</var>, unsigned int * <var>reasons</var>)</em></dt>
<dd><p><var>cdp</var>: The CRL distribution points
</p>
<p><var>seq</var>: specifies the sequence number of the distribution point (0 for the first one, 1 for the second etc.)
</p>
<p><var>type</var>: The name type of the corresponding name (gnutls_x509_subject_alt_name_t)
</p>
<p><var>san</var>: The distribution point names (to be treated as constant)
</p>
<p><var>reasons</var>: Revocation reasons. An ORed sequence of flags from <code>gnutls_x509_crl_reason_flags_t</code> .
</p>
<p>This function retrieves the individual CRL distribution points (2.5.29.31),
contained in provided type. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the index is out of bounds, otherwise a negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fdist_005fpoints_005finit-1"></a>
<h4 class="subheading">gnutls_x509_crl_dist_points_init</h4>
<a name="gnutls_005fx509_005fcrl_005fdist_005fpoints_005finit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fdist_005fpoints_005finit"></a>Function: <em>int</em> <strong>gnutls_x509_crl_dist_points_init</strong> <em>(gnutls_x509_crl_dist_points_t * <var>cdp</var>)</em></dt>
<dd><p><var>cdp</var>: The CRL distribution points
</p>
<p>This function will initialize a CRL distribution points type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fdist_005fpoints_005fset-1"></a>
<h4 class="subheading">gnutls_x509_crl_dist_points_set</h4>
<a name="gnutls_005fx509_005fcrl_005fdist_005fpoints_005fset"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fdist_005fpoints_005fset"></a>Function: <em>int</em> <strong>gnutls_x509_crl_dist_points_set</strong> <em>(gnutls_x509_crl_dist_points_t <var>cdp</var>, gnutls_x509_subject_alt_name_t <var>type</var>, const gnutls_datum_t * <var>san</var>, unsigned int <var>reasons</var>)</em></dt>
<dd><p><var>cdp</var>: The CRL distribution points
</p>
<p><var>type</var>: The type of the name (of <code>gnutls_subject_alt_names_t</code> )
</p>
<p><var>san</var>: The point name data
</p>
<p><var>reasons</var>: Revocation reasons. An ORed sequence of flags from <code>gnutls_x509_crl_reason_flags_t</code> .
</p>
<p>This function will store the specified CRL distibution point value
the  <code>cdp</code> type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0), otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fexport-1"></a>
<h4 class="subheading">gnutls_x509_crl_export</h4>
<a name="gnutls_005fx509_005fcrl_005fexport"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fexport"></a>Function: <em>int</em> <strong>gnutls_x509_crl_export</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_fmt_t <var>format</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>crl</var>: Holds the revocation list
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>output_data</var>: will contain a private key PEM or DER encoded
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will
be replaced by the actual size of parameters)
</p>
<p>This function will export the revocation list to DER or PEM format.
</p>
<p>If the buffer provided is not long enough to hold the output, then
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  will be returned.
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN X509 CRL&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fexport2-1"></a>
<h4 class="subheading">gnutls_x509_crl_export2</h4>
<a name="gnutls_005fx509_005fcrl_005fexport2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fexport2"></a>Function: <em>int</em> <strong>gnutls_x509_crl_export2</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_fmt_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>crl</var>: Holds the revocation list
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>out</var>: will contain a private key PEM or DER encoded
</p>
<p>This function will export the revocation list to DER or PEM format.
</p>
<p>The output buffer is allocated using <code>gnutls_malloc()</code> .
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN X509 CRL&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p>Since 3.1.3
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fauthority_005fkey_005fgn_005fserial-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_authority_key_gn_serial</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fauthority_005fkey_005fgn_005fserial"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fauthority_005fkey_005fgn_005fserial"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_authority_key_gn_serial</strong> <em>(gnutls_x509_crl_t <var>crl</var>, unsigned int <var>seq</var>, void * <var>alt</var>, size_t * <var>alt_size</var>, unsigned int * <var>alt_type</var>, void * <var>serial</var>, size_t * <var>serial_size</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p><var>seq</var>: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
</p>
<p><var>alt</var>: is the place where the alternative name will be copied to
</p>
<p><var>alt_size</var>: holds the size of alt.
</p>
<p><var>alt_type</var>: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).
</p>
<p><var>serial</var>: buffer to store the serial number (may be null)
</p>
<p><var>serial_size</var>: Holds the size of the serial field (may be null)
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical (may be null)
</p>
<p>This function will return the X.509 authority key
identifier when stored as a general name (authorityCertIssuer) 
and serial number.
</p>
<p>Because more than one general names might be stored
 <code>seq</code> can be used as a counter to request them all until 
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p>
<p><strong>Returns:</strong> Returns 0 on success, or an error code.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fauthority_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_authority_key_id</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fauthority_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fauthority_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_authority_key_id</strong> <em>(gnutls_x509_crl_t <var>crl</var>, void * <var>id</var>, size_t * <var>id_size</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p><var>id</var>: The place where the identifier will be copied
</p>
<p><var>id_size</var>: Holds the size of the result field.
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
(may be null)
</p>
<p>This function will return the CRL authority&rsquo;s key identifier.  This
is obtained by the X.509 Authority Key identifier extension field
(2.5.29.35).  Note that this function 
only returns the keyIdentifier field of the extension and
<code>GNUTLS_E_X509_UNSUPPORTED_EXTENSION</code> , if the extension contains
the name and serial number of the certificate. In that case
<code>gnutls_x509_crl_get_authority_key_gn_serial()</code>  may be used.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code in case of an error.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fcrt_005fcount-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_crt_count</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fcrt_005fcount"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fcrt_005fcount"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_crt_count</strong> <em>(gnutls_x509_crl_t <var>crl</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p>This function will return the number of revoked certificates in the
given CRL.
</p>
<p><strong>Returns:</strong> number of certificates, a negative error code on failure.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fcrt_005fserial-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_crt_serial</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fcrt_005fserial"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fcrt_005fserial-1"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_crt_serial</strong> <em>(gnutls_x509_crl_t <var>crl</var>, int <var>indx</var>, unsigned char * <var>serial</var>, size_t * <var>serial_size</var>, time_t * <var>t</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p><var>indx</var>: the index of the certificate to extract (starting from 0)
</p>
<p><var>serial</var>: where the serial number will be copied
</p>
<p><var>serial_size</var>: initially holds the size of serial
</p>
<p><var>t</var>: if non null, will hold the time this certificate was revoked
</p>
<p>This function will retrieve the serial number of the specified, by
the index, revoked certificate.
</p>
<p>Note that this function will have performance issues in large sequences
of revoked certificates. In that case use <code>gnutls_x509_crl_iter_crt_serial()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fdn_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_dn_oid</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fdn_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fdn_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_dn_oid</strong> <em>(gnutls_x509_crl_t <var>crl</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>sizeof_oid</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>indx</var>: Specifies which DN OID to send. Use (0) to get the first one.
</p>
<p><var>oid</var>: a pointer to store the OID (may be null)
</p>
<p><var>sizeof_oid</var>: initially holds the size of &rsquo;oid&rsquo;
</p>
<p>This function will extract the requested OID of the name of the CRL
issuer, specified by the given index.
</p>
<p>If oid is null then only the size will be filled.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is
not long enough, and in that case the sizeof_oid will be updated
with the required size.  On success 0 is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fextension_005fdata-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_extension_data</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fextension_005fdata"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fextension_005fdata"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_extension_data</strong> <em>(gnutls_x509_crl_t <var>crl</var>, int <var>indx</var>, void * <var>data</var>, size_t * <var>sizeof_data</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension OID to send. Use (0) to get the first one.
</p>
<p><var>data</var>: a pointer to a structure to hold the data (may be null)
</p>
<p><var>sizeof_data</var>: initially holds the size of  <code>oid</code> 
</p>
<p>This function will return the requested extension data in the CRL.
The extension data will be stored as a string in the provided
buffer.
</p>
<p>Use <code>gnutls_x509_crl_get_extension_info()</code>  to extract the OID and
critical flag.  Use <code>gnutls_x509_crl_get_extension_info()</code>  instead,
if you want to get data indexed by the extension OID rather than
sequence.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fextension_005fdata2-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_extension_data2</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fextension_005fdata2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fextension_005fdata2"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_extension_data2</strong> <em>(gnutls_x509_crl_t <var>crl</var>, unsigned <var>indx</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension OID to read. Use (0) to get the first one.
</p>
<p><var>data</var>: will contain the extension DER-encoded data
</p>
<p>This function will return the requested by the index extension data in the
certificate revocation list.  The extension data will be allocated using
<code>gnutls_malloc()</code> .
</p>
<p>Use <code>gnutls_x509_crt_get_extension_info()</code>  to extract the OID.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.  If you have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fextension_005finfo-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_extension_info</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fextension_005finfo"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fextension_005finfo"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_extension_info</strong> <em>(gnutls_x509_crl_t <var>crl</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>sizeof_oid</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension OID to send, use (0) to get the first one.
</p>
<p><var>oid</var>: a pointer to store the OID
</p>
<p><var>sizeof_oid</var>: initially holds the maximum size of  <code>oid</code> , on return
holds actual size of  <code>oid</code> .
</p>
<p><var>critical</var>: output variable with critical flag, may be NULL.
</p>
<p>This function will return the requested extension OID in the CRL,
and the critical flag for it.  The extension OID will be stored as
a string in the provided buffer.  Use
<code>gnutls_x509_crl_get_extension_data()</code>  to extract the data.
</p>
<p>If the buffer provided is not long enough to hold the output, then
* <code>sizeof_oid</code> is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  will be
returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fextension_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_extension_oid</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fextension_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fextension_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_extension_oid</strong> <em>(gnutls_x509_crl_t <var>crl</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>sizeof_oid</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension OID to send, use (0) to get the first one.
</p>
<p><var>oid</var>: a pointer to store the OID (may be null)
</p>
<p><var>sizeof_oid</var>: initially holds the size of  <code>oid</code> 
</p>
<p>This function will return the requested extension OID in the CRL.
The extension OID will be stored as a string in the provided
buffer.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_issuer_dn</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_issuer_dn</strong> <em>(const gnutls_x509_crl_t <var>crl</var>, char * <var>buf</var>, size_t * <var>sizeof_buf</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>buf</var>: a pointer to a structure to hold the peer&rsquo;s name (may be null)
</p>
<p><var>sizeof_buf</var>: initially holds the size of  <code>buf</code> 
</p>
<p>This function will copy the name of the CRL issuer in the provided
buffer. The name will be in the form &quot;C=xxxx,O=yyyy,CN=zzzz&quot; as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.
</p>
<p>If buf is <code>NULL</code>  then only the size will be filled.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is
not long enough, and in that case the sizeof_buf will be updated
with the required size, and 0 on success.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn2-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_issuer_dn2</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn2"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_issuer_dn2</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_datum_t * <var>dn</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p><var>dn</var>: a pointer to a structure to hold the name
</p>
<p>This function will allocate buffer and copy the name of the CRL issuer.
The name will be in the form &quot;C=xxxx,O=yyyy,CN=zzzz&quot; as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.10
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_issuer_dn_by_oid</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_issuer_dn_by_oid</strong> <em>(gnutls_x509_crl_t <var>crl</var>, const char * <var>oid</var>, int <var>indx</var>, unsigned int <var>raw_flag</var>, void * <var>buf</var>, size_t * <var>sizeof_buf</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>oid</var>: holds an Object Identified in null terminated string
</p>
<p><var>indx</var>: In case multiple same OIDs exist in the RDN, this specifies which to send. Use (0) to get the first one.
</p>
<p><var>raw_flag</var>: If non-zero returns the raw DER data of the DN part.
</p>
<p><var>buf</var>: a pointer to a structure to hold the peer&rsquo;s name (may be null)
</p>
<p><var>sizeof_buf</var>: initially holds the size of  <code>buf</code> 
</p>
<p>This function will extract the part of the name of the CRL issuer
specified by the given OID. The output will be encoded as described
in RFC4514. The output string will be ASCII or UTF-8 encoded,
depending on the certificate data.
</p>
<p>Some helper macros with popular OIDs can be found in gnutls/x509.h
If raw flag is (0), this function will only return known OIDs as
text. Other OIDs will be DER encoded, as described in RFC4514 &ndash; in
hex format with a &rsquo;#&rsquo; prefix.  You can check about known OIDs
using <code>gnutls_x509_dn_oid_known()</code> .
</p>
<p>If buf is null then only the size will be filled.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is
not long enough, and in that case the sizeof_buf will be updated
with the required size, and 0 on success.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fnext_005fupdate-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_next_update</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fnext_005fupdate"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fnext_005fupdate"></a>Function: <em>time_t</em> <strong>gnutls_x509_crl_get_next_update</strong> <em>(gnutls_x509_crl_t <var>crl</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p>This function will return the time the next CRL will be issued.
This field is optional in a CRL so it might be normal to get an
error instead.
</p>
<p><strong>Returns:</strong> when the next CRL will be issued, or (time_t)-1 on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fnumber-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_number</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fnumber"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fnumber"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_number</strong> <em>(gnutls_x509_crl_t <var>crl</var>, void * <var>ret</var>, size_t * <var>ret_size</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p><var>ret</var>: The place where the number will be copied
</p>
<p><var>ret_size</var>: Holds the size of the result field.
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
(may be null)
</p>
<p>This function will return the CRL number extension.  This is
obtained by the CRL Number extension field (2.5.29.20).
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code in case of an error.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fraw_005fissuer_005fdn-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_raw_issuer_dn</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fraw_005fissuer_005fdn"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fraw_005fissuer_005fdn"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_raw_issuer_dn</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_datum_t * <var>dn</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>dn</var>: will hold the starting point of the DN
</p>
<p>This function will return a pointer to the DER encoded DN structure
and the length.
</p>
<p><strong>Returns:</strong> a negative error code on error, and (0) on success.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fsignature-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_signature</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fsignature"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fsignature"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_signature</strong> <em>(gnutls_x509_crl_t <var>crl</var>, char * <var>sig</var>, size_t * <var>sizeof_sig</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>sig</var>: a pointer where the signature part will be copied (may be null).
</p>
<p><var>sizeof_sig</var>: initially holds the size of  <code>sig</code> 
</p>
<p>This function will extract the signature field of a CRL.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. 
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fsignature_005falgorithm-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_signature_algorithm</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fsignature_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fsignature_005falgorithm"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_signature_algorithm</strong> <em>(gnutls_x509_crl_t <var>crl</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p>This function will return a value of the <code>gnutls_sign_algorithm_t</code> 
enumeration that is the signature algorithm.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fthis_005fupdate-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_this_update</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fthis_005fupdate"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fthis_005fupdate"></a>Function: <em>time_t</em> <strong>gnutls_x509_crl_get_this_update</strong> <em>(gnutls_x509_crl_t <var>crl</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p>This function will return the time this CRL was issued.
</p>
<p><strong>Returns:</strong> when the CRL was issued, or (time_t)-1 on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fget_005fversion-1"></a>
<h4 class="subheading">gnutls_x509_crl_get_version</h4>
<a name="gnutls_005fx509_005fcrl_005fget_005fversion"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fget_005fversion"></a>Function: <em>int</em> <strong>gnutls_x509_crl_get_version</strong> <em>(gnutls_x509_crl_t <var>crl</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p>This function will return the version of the specified CRL.
</p>
<p><strong>Returns:</strong> The version number, or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fimport-1"></a>
<h4 class="subheading">gnutls_x509_crl_import</h4>
<a name="gnutls_005fx509_005fcrl_005fimport"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fimport"></a>Function: <em>int</em> <strong>gnutls_x509_crl_import</strong> <em>(gnutls_x509_crl_t <var>crl</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>crl</var>: The data to store the parsed CRL.
</p>
<p><var>data</var>: The DER or PEM encoded CRL.
</p>
<p><var>format</var>: One of DER or PEM
</p>
<p>This function will convert the given DER or PEM encoded CRL
to the native <code>gnutls_x509_crl_t</code>  format. The output will be stored in &rsquo;crl&rsquo;.
</p>
<p>If the CRL is PEM encoded it should have a header of &quot;X509 CRL&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005finit-1"></a>
<h4 class="subheading">gnutls_x509_crl_init</h4>
<a name="gnutls_005fx509_005fcrl_005finit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005finit"></a>Function: <em>int</em> <strong>gnutls_x509_crl_init</strong> <em>(gnutls_x509_crl_t * <var>crl</var>)</em></dt>
<dd><p><var>crl</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize a CRL structure. CRL stands for
Certificate Revocation List. A revocation list usually contains
lists of certificate serial numbers that have been revoked by an
Authority. The revocation lists are always signed with the
authority&rsquo;s private key.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fiter_005fcrt_005fserial-1"></a>
<h4 class="subheading">gnutls_x509_crl_iter_crt_serial</h4>
<a name="gnutls_005fx509_005fcrl_005fiter_005fcrt_005fserial"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fiter_005fcrt_005fserial"></a>Function: <em>int</em> <strong>gnutls_x509_crl_iter_crt_serial</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crl_iter_t * <var>iter</var>, unsigned char * <var>serial</var>, size_t * <var>serial_size</var>, time_t * <var>t</var>)</em></dt>
<dd><p><var>crl</var>: should contain a <code>gnutls_x509_crl_t</code>  type
</p>
<p><var>iter</var>: A pointer to an iterator (initially the iterator should be <code>NULL</code> )
</p>
<p><var>serial</var>: where the serial number will be copied
</p>
<p><var>serial_size</var>: initially holds the size of serial
</p>
<p><var>t</var>: if non null, will hold the time this certificate was revoked
</p>
<p>This function performs the same as <code>gnutls_x509_crl_get_crt_serial()</code> ,
but reads sequentially and keeps state in the iterator 
between calls. That allows it to provide better performance in sequences 
with many elements (50000+).
</p>
<p>When past the last element is accessed <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
is returned and the iterator is reset.
</p>
<p>After use, the iterator must be deinitialized using <code>gnutls_x509_crl_iter_deinit()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fiter_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_crl_iter_deinit</h4>
<a name="gnutls_005fx509_005fcrl_005fiter_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fiter_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_crl_iter_deinit</strong> <em>(gnutls_x509_crl_iter_t <var>iter</var>)</em></dt>
<dd><p><var>iter</var>: The iterator to be deinitialized
</p>
<p>This function will deinitialize an iterator type.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005flist_005fimport-1"></a>
<h4 class="subheading">gnutls_x509_crl_list_import</h4>
<a name="gnutls_005fx509_005fcrl_005flist_005fimport"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005flist_005fimport"></a>Function: <em>int</em> <strong>gnutls_x509_crl_list_import</strong> <em>(gnutls_x509_crl_t * <var>crls</var>, unsigned int * <var>crl_max</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crls</var>: Indicates where the parsed CRLs will be copied to. Must not be initialized.
</p>
<p><var>crl_max</var>: Initially must hold the maximum number of crls. It will be updated with the number of crls available.
</p>
<p><var>data</var>: The PEM encoded CRLs
</p>
<p><var>format</var>: One of DER or PEM.
</p>
<p><var>flags</var>: must be (0) or an OR&rsquo;d sequence of gnutls_certificate_import_flags.
</p>
<p>This function will convert the given PEM encoded CRL list
to the native gnutls_x509_crl_t format. The output will be stored
in  <code>crls</code> .  They will be automatically initialized.
</p>
<p>If the Certificate is PEM encoded it should have a header of &quot;X509 CRL&quot;.
</p>
<p><strong>Returns:</strong> the number of certificates read or a negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005flist_005fimport2-1"></a>
<h4 class="subheading">gnutls_x509_crl_list_import2</h4>
<a name="gnutls_005fx509_005fcrl_005flist_005fimport2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005flist_005fimport2"></a>Function: <em>int</em> <strong>gnutls_x509_crl_list_import2</strong> <em>(gnutls_x509_crl_t ** <var>crls</var>, unsigned int * <var>size</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crls</var>: Will contain the parsed crl list.
</p>
<p><var>size</var>: It will contain the size of the list.
</p>
<p><var>data</var>: The PEM encoded CRL.
</p>
<p><var>format</var>: One of DER or PEM.
</p>
<p><var>flags</var>: must be (0) or an OR&rsquo;d sequence of gnutls_certificate_import_flags.
</p>
<p>This function will convert the given PEM encoded CRL list
to the native gnutls_x509_crl_t format. The output will be stored
in  <code>crls</code> .  They will be automatically initialized.
</p>
<p>If the Certificate is PEM encoded it should have a header of &quot;X509
CRL&quot;.
</p>
<p><strong>Returns:</strong> the number of certificates read or a negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fprint-1"></a>
<h4 class="subheading">gnutls_x509_crl_print</h4>
<a name="gnutls_005fx509_005fcrl_005fprint"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fprint"></a>Function: <em>int</em> <strong>gnutls_x509_crl_print</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_certificate_print_formats_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>crl</var>: The data to be printed
</p>
<p><var>format</var>: Indicate the format to use
</p>
<p><var>out</var>: Newly allocated datum with null terminated string.
</p>
<p>This function will pretty print a X.509 certificate revocation
list, suitable for display to a human.
</p>
<p>The output  <code>out</code> needs to be deallocated using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fset_005fauthority_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_crl_set_authority_key_id</h4>
<a name="gnutls_005fx509_005fcrl_005fset_005fauthority_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fset_005fauthority_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_crl_set_authority_key_id</strong> <em>(gnutls_x509_crl_t <var>crl</var>, const void * <var>id</var>, size_t <var>id_size</var>)</em></dt>
<dd><p><var>crl</var>: a CRL of type <code>gnutls_x509_crl_t</code> 
</p>
<p><var>id</var>: The key ID
</p>
<p><var>id_size</var>: Holds the size of the serial field.
</p>
<p>This function will set the CRL&rsquo;s authority key ID extension.  Only
the keyIdentifier field can be set with this function. This may
be used by an authority that holds multiple private keys, to distinguish
the used key.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fset_005fcrt-1"></a>
<h4 class="subheading">gnutls_x509_crl_set_crt</h4>
<a name="gnutls_005fx509_005fcrl_005fset_005fcrt"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fset_005fcrt"></a>Function: <em>int</em> <strong>gnutls_x509_crl_set_crt</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_t <var>crt</var>, time_t <var>revocation_time</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code>  with the revoked certificate
</p>
<p><var>revocation_time</var>: The time this certificate was revoked
</p>
<p>This function will set a revoked certificate&rsquo;s serial number to the CRL.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fset_005fcrt_005fserial-1"></a>
<h4 class="subheading">gnutls_x509_crl_set_crt_serial</h4>
<a name="gnutls_005fx509_005fcrl_005fset_005fcrt_005fserial"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fset_005fcrt_005fserial"></a>Function: <em>int</em> <strong>gnutls_x509_crl_set_crt_serial</strong> <em>(gnutls_x509_crl_t <var>crl</var>, const void * <var>serial</var>, size_t <var>serial_size</var>, time_t <var>revocation_time</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>serial</var>: The revoked certificate&rsquo;s serial number
</p>
<p><var>serial_size</var>: Holds the size of the serial field.
</p>
<p><var>revocation_time</var>: The time this certificate was revoked
</p>
<p>This function will set a revoked certificate&rsquo;s serial number to the CRL.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fset_005fnext_005fupdate-1"></a>
<h4 class="subheading">gnutls_x509_crl_set_next_update</h4>
<a name="gnutls_005fx509_005fcrl_005fset_005fnext_005fupdate"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fset_005fnext_005fupdate"></a>Function: <em>int</em> <strong>gnutls_x509_crl_set_next_update</strong> <em>(gnutls_x509_crl_t <var>crl</var>, time_t <var>exp_time</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>exp_time</var>: The actual time
</p>
<p>This function will set the time this CRL will be updated.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fset_005fnumber-1"></a>
<h4 class="subheading">gnutls_x509_crl_set_number</h4>
<a name="gnutls_005fx509_005fcrl_005fset_005fnumber"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fset_005fnumber"></a>Function: <em>int</em> <strong>gnutls_x509_crl_set_number</strong> <em>(gnutls_x509_crl_t <var>crl</var>, const void * <var>nr</var>, size_t <var>nr_size</var>)</em></dt>
<dd><p><var>crl</var>: a CRL of type <code>gnutls_x509_crl_t</code> 
</p>
<p><var>nr</var>: The CRL number
</p>
<p><var>nr_size</var>: Holds the size of the nr field.
</p>
<p>This function will set the CRL&rsquo;s number extension. This
is to be used as a unique and monotonic number assigned to
the CRL by the authority.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fset_005fthis_005fupdate-1"></a>
<h4 class="subheading">gnutls_x509_crl_set_this_update</h4>
<a name="gnutls_005fx509_005fcrl_005fset_005fthis_005fupdate"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fset_005fthis_005fupdate"></a>Function: <em>int</em> <strong>gnutls_x509_crl_set_this_update</strong> <em>(gnutls_x509_crl_t <var>crl</var>, time_t <var>act_time</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>act_time</var>: The actual time
</p>
<p>This function will set the time this CRL was issued.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fset_005fversion-1"></a>
<h4 class="subheading">gnutls_x509_crl_set_version</h4>
<a name="gnutls_005fx509_005fcrl_005fset_005fversion"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fset_005fversion"></a>Function: <em>int</em> <strong>gnutls_x509_crl_set_version</strong> <em>(gnutls_x509_crl_t <var>crl</var>, unsigned int <var>version</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>version</var>: holds the version number. For CRLv1 crls must be 1.
</p>
<p>This function will set the version of the CRL. This
must be one for CRL version 1, and so on. The CRLs generated
by gnutls should have a version number of 2.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fsign2-1"></a>
<h4 class="subheading">gnutls_x509_crl_sign2</h4>
<a name="gnutls_005fx509_005fcrl_005fsign2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fsign2-1"></a>Function: <em>int</em> <strong>gnutls_x509_crl_sign2</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_t <var>issuer</var>, gnutls_x509_privkey_t <var>issuer_key</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>issuer</var>: is the certificate of the certificate issuer
</p>
<p><var>issuer_key</var>: holds the issuer&rsquo;s private key
</p>
<p><var>dig</var>: The message digest to use. GNUTLS_DIG_SHA1 is the safe choice unless you know what you&rsquo;re doing.
</p>
<p><var>flags</var>: must be 0
</p>
<p>This function will sign the CRL with the issuer&rsquo;s private key, and
will copy the issuer&rsquo;s information into the CRL.
</p>
<p>This must be the last step in a certificate CRL since all
the previously set parameters are now signed.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fverify-1"></a>
<h4 class="subheading">gnutls_x509_crl_verify</h4>
<a name="gnutls_005fx509_005fcrl_005fverify"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fverify"></a>Function: <em>int</em> <strong>gnutls_x509_crl_verify</strong> <em>(gnutls_x509_crl_t <var>crl</var>, const gnutls_x509_crt_t * <var>trusted_cas</var>, int <var>tcas_size</var>, unsigned int <var>flags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>crl</var>: is the crl to be verified
</p>
<p><var>trusted_cas</var>: is a certificate list that is considered to be trusted one
</p>
<p><var>tcas_size</var>: holds the number of CA certificates in CA_list
</p>
<p><var>flags</var>: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.
</p>
<p><var>verify</var>: will hold the crl verification output.
</p>
<p>This function will try to verify the given crl and return its verification status.
See <code>gnutls_x509_crt_list_verify()</code>  for a detailed description of
return values. Note that since GnuTLS 3.1.4 this function includes
the time checks.
</p>
<p>Note that value in  <code>verify</code> is set only when the return value of this 
function is success (i.e, failure to trust a CRL a certificate does not imply 
a negative return value).
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_crq_deinit</h4>
<a name="gnutls_005fx509_005fcrq_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_crq_deinit</strong> <em>(gnutls_x509_crq_t <var>crq</var>)</em></dt>
<dd><p><var>crq</var>: the type to be deinitialized
</p>
<p>This function will deinitialize a PKCS<code>10</code>  certificate request
structure.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fexport-1"></a>
<h4 class="subheading">gnutls_x509_crq_export</h4>
<a name="gnutls_005fx509_005fcrq_005fexport"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fexport"></a>Function: <em>int</em> <strong>gnutls_x509_crq_export</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_x509_crt_fmt_t <var>format</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>output_data</var>: will contain a certificate request PEM or DER encoded
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will export the certificate request to a PEM or DER
encoded PKCS10 structure.
</p>
<p>If the buffer provided is not long enough to hold the output, then
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  will be returned and
* <code>output_data_size</code> will be updated.
</p>
<p>If the structure is PEM encoded, it will have a header of &quot;BEGIN
NEW CERTIFICATE REQUEST&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fexport2-1"></a>
<h4 class="subheading">gnutls_x509_crq_export2</h4>
<a name="gnutls_005fx509_005fcrq_005fexport2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fexport2"></a>Function: <em>int</em> <strong>gnutls_x509_crq_export2</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_x509_crt_fmt_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>out</var>: will contain a certificate request PEM or DER encoded
</p>
<p>This function will export the certificate request to a PEM or DER
encoded PKCS10 structure.
</p>
<p>The output buffer is allocated using <code>gnutls_malloc()</code> .
</p>
<p>If the structure is PEM encoded, it will have a header of &quot;BEGIN
NEW CERTIFICATE REQUEST&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p>Since 3.1.3
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fattribute_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_attribute_by_oid</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fattribute_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fattribute_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_attribute_by_oid</strong> <em>(gnutls_x509_crq_t <var>crq</var>, const char * <var>oid</var>, int <var>indx</var>, void * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>oid</var>: holds an Object Identifier in null-terminated string
</p>
<p><var>indx</var>: In case multiple same OIDs exist in the attribute list, this
specifies which to get, use (0) to get the first one
</p>
<p><var>buf</var>: a pointer to a structure to hold the attribute data (may be <code>NULL</code> )
</p>
<p><var>buf_size</var>: initially holds the size of  <code>buf</code> 
</p>
<p>This function will return the attribute in the certificate request
specified by the given Object ID.  The attribute will be DER
encoded.
</p>
<p>Attributes in a certificate request is an optional set of data
appended to the request. Their interpretation depends on the CA policy.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fattribute_005fdata-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_attribute_data</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fattribute_005fdata"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fattribute_005fdata"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_attribute_data</strong> <em>(gnutls_x509_crq_t <var>crq</var>, int <var>indx</var>, void * <var>data</var>, size_t * <var>sizeof_data</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>indx</var>: Specifies which attribute number to get. Use (0) to get the first one.
</p>
<p><var>data</var>: a pointer to a structure to hold the data (may be null)
</p>
<p><var>sizeof_data</var>: initially holds the size of  <code>oid</code> 
</p>
<p>This function will return the requested attribute data in the
certificate request.  The attribute data will be stored as a string in the
provided buffer.
</p>
<p>Use <code>gnutls_x509_crq_get_attribute_info()</code>  to extract the OID.
Use <code>gnutls_x509_crq_get_attribute_by_oid()</code>  instead,
if you want to get data indexed by the attribute OID rather than
sequence.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fattribute_005finfo-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_attribute_info</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fattribute_005finfo"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fattribute_005finfo"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_attribute_info</strong> <em>(gnutls_x509_crq_t <var>crq</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>sizeof_oid</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>indx</var>: Specifies which attribute number to get. Use (0) to get the first one.
</p>
<p><var>oid</var>: a pointer to a structure to hold the OID
</p>
<p><var>sizeof_oid</var>: initially holds the maximum size of  <code>oid</code> , on return
holds actual size of  <code>oid</code> .
</p>
<p>This function will return the requested attribute OID in the
certificate, and the critical flag for it.  The attribute OID will
be stored as a string in the provided buffer.  Use
<code>gnutls_x509_crq_get_attribute_data()</code>  to extract the data.
</p>
<p>If the buffer provided is not long enough to hold the output, then
* <code>sizeof_oid</code> is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  will be
returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fbasic_005fconstraints-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_basic_constraints</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fbasic_005fconstraints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fbasic_005fconstraints"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_basic_constraints</strong> <em>(gnutls_x509_crq_t <var>crq</var>, unsigned int * <var>critical</var>, unsigned int * <var>ca</var>, int * <var>pathlen</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
</p>
<p><var>ca</var>: pointer to output integer indicating CA status, may be NULL,
value is 1 if the certificate CA flag is set, 0 otherwise.
</p>
<p><var>pathlen</var>: pointer to output integer indicating path length (may be
NULL), non-negative error codes indicate a present pathLenConstraint
field and the actual value, -1 indicate that the field is absent.
</p>
<p>This function will read the certificate&rsquo;s basic constraints, and
return the certificates CA status.  It reads the basicConstraints
X.509 extension (2.5.29.19).
</p>
<p><strong>Returns:</strong> If the certificate is a CA a positive value will be
returned, or (0) if the certificate does not have CA flag set.
A negative error code may be returned in case of errors.  If the
certificate does not contain the basicConstraints extension
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fchallenge_005fpassword-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_challenge_password</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fchallenge_005fpassword"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fchallenge_005fpassword"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_challenge_password</strong> <em>(gnutls_x509_crq_t <var>crq</var>, char * <var>pass</var>, size_t * <var>pass_size</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>pass</var>: will hold a (0)-terminated password string
</p>
<p><var>pass_size</var>: Initially holds the size of  <code>pass</code> .
</p>
<p>This function will return the challenge password in the request.
The challenge password is intended to be used for requesting a
revocation of the certificate.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fdn-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_dn</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fdn"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fdn"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_dn</strong> <em>(gnutls_x509_crq_t <var>crq</var>, char * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>buf</var>: a pointer to a structure to hold the name (may be <code>NULL</code> )
</p>
<p><var>buf_size</var>: initially holds the size of  <code>buf</code> 
</p>
<p>This function will copy the name of the Certificate request subject
to the provided buffer.  The name will be in the form
&quot;C=xxxx,O=yyyy,CN=zzzz&quot; as described in RFC 2253. The output string
 <code>buf</code> will be ASCII or UTF-8 encoded, depending on the certificate
data.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is not
long enough, and in that case the * <code>buf_size</code> will be updated with
the required size.  On success 0 is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fdn2-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_dn2</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fdn2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fdn2"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_dn2</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_datum_t * <var>dn</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>dn</var>: a pointer to a structure to hold the name
</p>
<p>This function will allocate buffer and copy the name of the Certificate 
request. The name will be in the form &quot;C=xxxx,O=yyyy,CN=zzzz&quot; as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. and a negative error code on error.
</p>
<p><strong>Since:</strong> 3.1.10
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fdn_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_dn_by_oid</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fdn_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fdn_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_dn_by_oid</strong> <em>(gnutls_x509_crq_t <var>crq</var>, const char * <var>oid</var>, int <var>indx</var>, unsigned int <var>raw_flag</var>, void * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>crq</var>: should contain a gnutls_x509_crq_t type
</p>
<p><var>oid</var>: holds an Object Identifier in a null terminated string
</p>
<p><var>indx</var>: In case multiple same OIDs exist in the RDN, this specifies
which to get. Use (0) to get the first one.
</p>
<p><var>raw_flag</var>: If non-zero returns the raw DER data of the DN part.
</p>
<p><var>buf</var>: a pointer to a structure to hold the name (may be <code>NULL</code> )
</p>
<p><var>buf_size</var>: initially holds the size of  <code>buf</code> 
</p>
<p>This function will extract the part of the name of the Certificate
request subject, specified by the given OID. The output will be
encoded as described in RFC2253. The output string will be ASCII
or UTF-8 encoded, depending on the certificate data.
</p>
<p>Some helper macros with popular OIDs can be found in gnutls/x509.h
If raw flag is (0), this function will only return known OIDs as
text. Other OIDs will be DER encoded, as described in RFC2253 &ndash;
in hex format with a &rsquo;\#&rsquo; prefix.  You can check about known OIDs
using <code>gnutls_x509_dn_oid_known()</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is
not long enough, and in that case the * <code>buf_size</code> will be
updated with the required size.  On success 0 is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fdn_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_dn_oid</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fdn_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fdn_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_dn_oid</strong> <em>(gnutls_x509_crq_t <var>crq</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>sizeof_oid</var>)</em></dt>
<dd><p><var>crq</var>: should contain a gnutls_x509_crq_t type
</p>
<p><var>indx</var>: Specifies which DN OID to get. Use (0) to get the first one.
</p>
<p><var>oid</var>: a pointer to a structure to hold the name (may be <code>NULL</code> )
</p>
<p><var>sizeof_oid</var>: initially holds the size of  <code>oid</code> 
</p>
<p>This function will extract the requested OID of the name of the
certificate request subject, specified by the given index.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is
not long enough, and in that case the * <code>sizeof_oid</code> will be
updated with the required size.  On success 0 is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fextension_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_extension_by_oid</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fextension_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fextension_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_extension_by_oid</strong> <em>(gnutls_x509_crq_t <var>crq</var>, const char * <var>oid</var>, int <var>indx</var>, void * <var>buf</var>, size_t * <var>buf_size</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>oid</var>: holds an Object Identifier in a null terminated string
</p>
<p><var>indx</var>: In case multiple same OIDs exist in the extensions, this
specifies which to get. Use (0) to get the first one.
</p>
<p><var>buf</var>: a pointer to a structure to hold the name (may be null)
</p>
<p><var>buf_size</var>: initially holds the size of  <code>buf</code> 
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
</p>
<p>This function will return the extension specified by the OID in
the certificate.  The extensions will be returned as binary data
DER encoded, in the provided buffer.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code in case of an error.  If the certificate does not
contain the specified extension
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fextension_005fby_005foid2-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_extension_by_oid2</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fextension_005fby_005foid2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fextension_005fby_005foid2"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_extension_by_oid2</strong> <em>(gnutls_x509_crq_t <var>crq</var>, const char * <var>oid</var>, int <var>indx</var>, gnutls_datum_t * <var>output</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>oid</var>: holds an Object Identifier in a null terminated string
</p>
<p><var>indx</var>: In case multiple same OIDs exist in the extensions, this
specifies which to get. Use (0) to get the first one.
</p>
<p><var>output</var>: will hold the allocated extension data
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
</p>
<p>This function will return the extension specified by the OID in
the certificate.  The extensions will be returned as binary data
DER encoded, in the provided buffer.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code in case of an error.  If the certificate does not
contain the specified extension
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be returned.
</p>
<p><strong>Since:</strong> 3.3.8
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fextension_005fdata-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_extension_data</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fextension_005fdata"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fextension_005fdata"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_extension_data</strong> <em>(gnutls_x509_crq_t <var>crq</var>, int <var>indx</var>, void * <var>data</var>, size_t * <var>sizeof_data</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension number to get. Use (0) to get the first one.
</p>
<p><var>data</var>: a pointer to a structure to hold the data (may be null)
</p>
<p><var>sizeof_data</var>: initially holds the size of  <code>oid</code> 
</p>
<p>This function will return the requested extension data in the
certificate.  The extension data will be stored as a string in the
provided buffer.
</p>
<p>Use <code>gnutls_x509_crq_get_extension_info()</code>  to extract the OID and
critical flag.  Use <code>gnutls_x509_crq_get_extension_by_oid()</code>  instead,
if you want to get data indexed by the extension OID rather than
sequence.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fextension_005fdata2-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_extension_data2</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fextension_005fdata2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fextension_005fdata2"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_extension_data2</strong> <em>(gnutls_x509_crq_t <var>crq</var>, unsigned <var>indx</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension OID to read. Use (0) to get the first one.
</p>
<p><var>data</var>: will contain the extension DER-encoded data
</p>
<p>This function will return the requested extension data in the
certificate request.  The extension data will be allocated using
<code>gnutls_malloc()</code> .
</p>
<p>Use <code>gnutls_x509_crq_get_extension_info()</code>  to extract the OID.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.  If you have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fextension_005finfo-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_extension_info</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fextension_005finfo"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fextension_005finfo"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_extension_info</strong> <em>(gnutls_x509_crq_t <var>crq</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>sizeof_oid</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension number to get. Use (0) to get the first one.
</p>
<p><var>oid</var>: a pointer to store the OID
</p>
<p><var>sizeof_oid</var>: initially holds the maximum size of  <code>oid</code> , on return
holds actual size of  <code>oid</code> .
</p>
<p><var>critical</var>: output variable with critical flag, may be NULL.
</p>
<p>This function will return the requested extension OID in the
certificate, and the critical flag for it.  The extension OID will
be stored as a string in the provided buffer.  Use
<code>gnutls_x509_crq_get_extension_data()</code>  to extract the data.
</p>
<p>If the buffer provided is not long enough to hold the output, then
* <code>sizeof_oid</code> is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  will be
returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code in case of an error.  If your have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_key_id</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_key_id</strong> <em>(gnutls_x509_crq_t <var>crq</var>, unsigned int <var>flags</var>, unsigned char * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>crq</var>: a certificate of type <code>gnutls_x509_crq_t</code> 
</p>
<p><var>flags</var>: should be one of the flags from <code>gnutls_keyid_flags_t</code> 
</p>
<p><var>output_data</var>: will contain the key ID
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will return a unique ID that depends on the public key
parameters.  This ID can be used in checking whether a certificate
corresponds to the given private key.
</p>
<p>If the buffer provided is not long enough to hold the output, then
* <code>output_data_size</code> is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
be returned.  The output will normally be a SHA-1 hash output,
which is 20 bytes.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fkey_005fpurpose_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_key_purpose_oid</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fkey_005fpurpose_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fkey_005fpurpose_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_key_purpose_oid</strong> <em>(gnutls_x509_crq_t <var>crq</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>sizeof_oid</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>indx</var>: This specifies which OID to return, use (0) to get the first one
</p>
<p><var>oid</var>: a pointer to store the OID (may be <code>NULL</code> )
</p>
<p><var>sizeof_oid</var>: initially holds the size of  <code>oid</code> 
</p>
<p><var>critical</var>: output variable with critical flag, may be <code>NULL</code> .
</p>
<p>This function will extract the key purpose OIDs of the Certificate
specified by the given index.  These are stored in the Extended Key
Usage extension (2.5.29.37).  See the GNUTLS_KP_* definitions for
human readable names.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is
not long enough, and in that case the * <code>sizeof_oid</code> will be
updated with the required size.  On success 0 is returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fkey_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_key_rsa_raw</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fkey_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fkey_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_key_rsa_raw</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_datum_t * <var>m</var>, gnutls_datum_t * <var>e</var>)</em></dt>
<dd><p><var>crq</var>: Holds the certificate
</p>
<p><var>m</var>: will hold the modulus
</p>
<p><var>e</var>: will hold the public exponent
</p>
<p>This function will export the RSA public key&rsquo;s parameters found in
the given structure.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fkey_005fusage-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_key_usage</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fkey_005fusage"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fkey_005fusage"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_key_usage</strong> <em>(gnutls_x509_crq_t <var>crq</var>, unsigned int * <var>key_usage</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>key_usage</var>: where the key usage bits will be stored
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
</p>
<p>This function will return certificate&rsquo;s key usage, by reading the
keyUsage X.509 extension (2.5.29.15).  The key usage value will
ORed values of the: <code>GNUTLS_KEY_DIGITAL_SIGNATURE</code> ,
<code>GNUTLS_KEY_NON_REPUDIATION</code> , <code>GNUTLS_KEY_KEY_ENCIPHERMENT</code> ,
<code>GNUTLS_KEY_DATA_ENCIPHERMENT</code> , <code>GNUTLS_KEY_KEY_AGREEMENT</code> ,
<code>GNUTLS_KEY_KEY_CERT_SIGN</code> , <code>GNUTLS_KEY_CRL_SIGN</code> ,
<code>GNUTLS_KEY_ENCIPHER_ONLY</code> , <code>GNUTLS_KEY_DECIPHER_ONLY</code> .
</p>
<p><strong>Returns:</strong> the certificate key usage, or a negative error code in case of
parsing error.  If the certificate does not contain the keyUsage
extension <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be
returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fpk_005falgorithm-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_pk_algorithm</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fpk_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fpk_005falgorithm"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_pk_algorithm</strong> <em>(gnutls_x509_crq_t <var>crq</var>, unsigned int * <var>bits</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>bits</var>: if bits is non-<code>NULL</code>  it will hold the size of the parameters&rsquo; in bits
</p>
<p>This function will return the public key algorithm of a PKCS<code>10</code> 
certificate request.
</p>
<p>If bits is non-<code>NULL</code> , it should have enough size to hold the
parameters size in bits.  For RSA the bits returned is the modulus.
For DSA the bits returned are of the public exponent.
</p>
<p><strong>Returns:</strong> a member of the <code>gnutls_pk_algorithm_t</code>  enumeration on
success, or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fprivate_005fkey_005fusage_005fperiod-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_private_key_usage_period</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fprivate_005fkey_005fusage_005fperiod"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fprivate_005fkey_005fusage_005fperiod"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_private_key_usage_period</strong> <em>(gnutls_x509_crq_t <var>crq</var>, time_t * <var>activation</var>, time_t * <var>expiration</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>activation</var>: The activation time
</p>
<p><var>expiration</var>: The expiration time
</p>
<p><var>critical</var>: the extension status
</p>
<p>This function will return the expiration and activation
times of the private key of the certificate.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the extension is not present, otherwise a negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fsignature_005falgorithm-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_signature_algorithm</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fsignature_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fsignature_005falgorithm"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_signature_algorithm</strong> <em>(gnutls_x509_crq_t <var>crq</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_cr_t</code>  type
</p>
<p>This function will return a value of the <code>gnutls_sign_algorithm_t</code> 
enumeration that is the signature algorithm that has been used to
sign this certificate request.
</p>
<p><strong>Returns:</strong> a <code>gnutls_sign_algorithm_t</code>  value, or a negative error code on
error.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fsubject_005falt_005fname-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_subject_alt_name</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fsubject_005falt_005fname"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fsubject_005falt_005fname"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_subject_alt_name</strong> <em>(gnutls_x509_crq_t <var>crq</var>, unsigned int <var>seq</var>, void * <var>ret</var>, size_t * <var>ret_size</var>, unsigned int * <var>ret_type</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>seq</var>: specifies the sequence number of the alt name, 0 for the
first one, 1 for the second etc.
</p>
<p><var>ret</var>: is the place where the alternative name will be copied to
</p>
<p><var>ret_size</var>: holds the size of ret.
</p>
<p><var>ret_type</var>: holds the <code>gnutls_x509_subject_alt_name_t</code>  name type
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
(may be null)
</p>
<p>This function will return the alternative names, contained in the
given certificate.  It is the same as
<code>gnutls_x509_crq_get_subject_alt_name()</code>  except for the fact that it
will return the type of the alternative name in  <code>ret_type</code> even if
the function fails for some reason (i.e.  the buffer provided is
not enough).
</p>
<p><strong>Returns:</strong> the alternative subject name type on success, one of the
enumerated <code>gnutls_x509_subject_alt_name_t</code> .  It will return
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if  <code>ret_size</code> is not large enough to
hold the value.  In that case  <code>ret_size</code> will be updated with the
required size.  If the certificate request does not have an
Alternative name with the specified sequence number then
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fsubject_005falt_005fothername_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_subject_alt_othername_oid</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fsubject_005falt_005fothername_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fsubject_005falt_005fothername_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_subject_alt_othername_oid</strong> <em>(gnutls_x509_crq_t <var>crq</var>, unsigned int <var>seq</var>, void * <var>ret</var>, size_t * <var>ret_size</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>seq</var>: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
</p>
<p><var>ret</var>: is the place where the otherName OID will be copied to
</p>
<p><var>ret_size</var>: holds the size of ret.
</p>
<p>This function will extract the type OID of an otherName Subject
Alternative Name, contained in the given certificate, and return
the type as an enumerated element.
</p>
<p>This function is only useful if
<code>gnutls_x509_crq_get_subject_alt_name()</code>  returned
<code>GNUTLS_SAN_OTHERNAME</code> .
</p>
<p><strong>Returns:</strong> the alternative subject name type on success, one of the
enumerated gnutls_x509_subject_alt_name_t.  For supported OIDs,
it will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types,
e.g. <code>GNUTLS_SAN_OTHERNAME_XMPP</code> , and <code>GNUTLS_SAN_OTHERNAME</code>  for
unknown OIDs.  It will return <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if
 <code>ret_size</code> is not large enough to hold the value.  In that case
 <code>ret_size</code> will be updated with the required size.  If the
certificate does not have an Alternative name with the specified
sequence number and with the otherName type then
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fget_005fversion-1"></a>
<h4 class="subheading">gnutls_x509_crq_get_version</h4>
<a name="gnutls_005fx509_005fcrq_005fget_005fversion"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fget_005fversion"></a>Function: <em>int</em> <strong>gnutls_x509_crq_get_version</strong> <em>(gnutls_x509_crq_t <var>crq</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p>This function will return the version of the specified Certificate
request.
</p>
<p><strong>Returns:</strong> version of certificate request, or a negative error code on
error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fimport-1"></a>
<h4 class="subheading">gnutls_x509_crq_import</h4>
<a name="gnutls_005fx509_005fcrq_005fimport"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fimport"></a>Function: <em>int</em> <strong>gnutls_x509_crq_import</strong> <em>(gnutls_x509_crq_t <var>crq</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>crq</var>: The data to store the parsed certificate request.
</p>
<p><var>data</var>: The DER or PEM encoded certificate.
</p>
<p><var>format</var>: One of DER or PEM
</p>
<p>This function will convert the given DER or PEM encoded certificate
request to a <code>gnutls_x509_crq_t</code>  type.  The output will be
stored in  <code>crq</code> .
</p>
<p>If the Certificate is PEM encoded it should have a header of &quot;NEW
CERTIFICATE REQUEST&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005finit-1"></a>
<h4 class="subheading">gnutls_x509_crq_init</h4>
<a name="gnutls_005fx509_005fcrq_005finit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005finit"></a>Function: <em>int</em> <strong>gnutls_x509_crq_init</strong> <em>(gnutls_x509_crq_t * <var>crq</var>)</em></dt>
<dd><p><var>crq</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize a PKCS<code>10</code>  certificate request
structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fprint-1"></a>
<h4 class="subheading">gnutls_x509_crq_print</h4>
<a name="gnutls_005fx509_005fcrq_005fprint"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fprint"></a>Function: <em>int</em> <strong>gnutls_x509_crq_print</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_certificate_print_formats_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>crq</var>: The data to be printed
</p>
<p><var>format</var>: Indicate the format to use
</p>
<p><var>out</var>: Newly allocated datum with null terminated string.
</p>
<p>This function will pretty print a certificate request, suitable for
display to a human.
</p>
<p>The output  <code>out</code> needs to be deallocated using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fattribute_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_attribute_by_oid</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fattribute_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fattribute_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_attribute_by_oid</strong> <em>(gnutls_x509_crq_t <var>crq</var>, const char * <var>oid</var>, void * <var>buf</var>, size_t <var>buf_size</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>oid</var>: holds an Object Identifier in a null-terminated string
</p>
<p><var>buf</var>: a pointer to a structure that holds the attribute data
</p>
<p><var>buf_size</var>: holds the size of  <code>buf</code> 
</p>
<p>This function will set the attribute in the certificate request
specified by the given Object ID. The provided attribute must be be DER
encoded.
</p>
<p>Attributes in a certificate request is an optional set of data
appended to the request. Their interpretation depends on the CA policy.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fbasic_005fconstraints-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_basic_constraints</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fbasic_005fconstraints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fbasic_005fconstraints"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_basic_constraints</strong> <em>(gnutls_x509_crq_t <var>crq</var>, unsigned int <var>ca</var>, int <var>pathLenConstraint</var>)</em></dt>
<dd><p><var>crq</var>: a certificate request of type <code>gnutls_x509_crq_t</code> 
</p>
<p><var>ca</var>: true(1) or false(0) depending on the Certificate authority status.
</p>
<p><var>pathLenConstraint</var>: non-negative error codes indicate maximum length of path,
and negative error codes indicate that the pathLenConstraints field should
not be present.
</p>
<p>This function will set the basicConstraints certificate extension.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fchallenge_005fpassword-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_challenge_password</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fchallenge_005fpassword"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fchallenge_005fpassword"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_challenge_password</strong> <em>(gnutls_x509_crq_t <var>crq</var>, const char * <var>pass</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>pass</var>: holds a (0)-terminated password
</p>
<p>This function will set a challenge password to be used when
revoking the request.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fdn-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_dn</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fdn"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fdn"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_dn</strong> <em>(gnutls_x509_crq_t <var>crq</var>, const char * <var>dn</var>, const char ** <var>err</var>)</em></dt>
<dd><p><var>crq</var>: a certificate of type <code>gnutls_x509_crq_t</code> 
</p>
<p><var>dn</var>: a comma separated DN string (RFC4514)
</p>
<p><var>err</var>: indicates the error position (if any)
</p>
<p>This function will set the DN on the provided certificate.
The input string should be plain ASCII or UTF-8 encoded.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fdn_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_dn_by_oid</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fdn_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fdn_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_dn_by_oid</strong> <em>(gnutls_x509_crq_t <var>crq</var>, const char * <var>oid</var>, unsigned int <var>raw_flag</var>, const void * <var>data</var>, unsigned int <var>sizeof_data</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>oid</var>: holds an Object Identifier in a (0)-terminated string
</p>
<p><var>raw_flag</var>: must be 0, or 1 if the data are DER encoded
</p>
<p><var>data</var>: a pointer to the input data
</p>
<p><var>sizeof_data</var>: holds the size of  <code>data</code> 
</p>
<p>This function will set the part of the name of the Certificate
request subject, specified by the given OID.  The input string
should be ASCII or UTF-8 encoded.
</p>
<p>Some helper macros with popular OIDs can be found in gnutls/x509.h
With this function you can only set the known OIDs.  You can test
for known OIDs using <code>gnutls_x509_dn_oid_known()</code> .  For OIDs that are
not known (by gnutls) you should properly DER encode your data, and
call this function with raw_flag set.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fkey-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_key</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fkey"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fkey-1"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_key</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_x509_privkey_t <var>key</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>key</var>: holds a private key
</p>
<p>This function will set the public parameters from the given private
key to the request.  
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fkey_005fpurpose_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_key_purpose_oid</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fkey_005fpurpose_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fkey_005fpurpose_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_key_purpose_oid</strong> <em>(gnutls_x509_crq_t <var>crq</var>, const void * <var>oid</var>, unsigned int <var>critical</var>)</em></dt>
<dd><p><var>crq</var>: a certificate of type <code>gnutls_x509_crq_t</code> 
</p>
<p><var>oid</var>: a pointer to a null-terminated string that holds the OID
</p>
<p><var>critical</var>: Whether this extension will be critical or not
</p>
<p>This function will set the key purpose OIDs of the Certificate.
These are stored in the Extended Key Usage extension (2.5.29.37)
See the GNUTLS_KP_* definitions for human readable names.
</p>
<p>Subsequent calls to this function will append OIDs to the OID list.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fkey_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_key_rsa_raw</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fkey_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fkey_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_key_rsa_raw</strong> <em>(gnutls_x509_crq_t <var>crq</var>, const gnutls_datum_t * <var>m</var>, const gnutls_datum_t * <var>e</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>m</var>: holds the modulus
</p>
<p><var>e</var>: holds the public exponent
</p>
<p>This function will set the public parameters from the given private
key to the request. Only RSA keys are currently supported.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.6.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fkey_005fusage-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_key_usage</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fkey_005fusage"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fkey_005fusage"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_key_usage</strong> <em>(gnutls_x509_crq_t <var>crq</var>, unsigned int <var>usage</var>)</em></dt>
<dd><p><var>crq</var>: a certificate request of type <code>gnutls_x509_crq_t</code> 
</p>
<p><var>usage</var>: an ORed sequence of the GNUTLS_KEY_* elements.
</p>
<p>This function will set the keyUsage certificate extension.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fprivate_005fkey_005fusage_005fperiod-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_private_key_usage_period</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fprivate_005fkey_005fusage_005fperiod"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fprivate_005fkey_005fusage_005fperiod"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_private_key_usage_period</strong> <em>(gnutls_x509_crq_t <var>crq</var>, time_t <var>activation</var>, time_t <var>expiration</var>)</em></dt>
<dd><p><var>crq</var>: a certificate of type <code>gnutls_x509_crq_t</code> 
</p>
<p><var>activation</var>: The activation time
</p>
<p><var>expiration</var>: The expiration time
</p>
<p>This function will set the private key usage period extension (2.5.29.16).
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fsubject_005falt_005fname-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_subject_alt_name</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fsubject_005falt_005fname"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fsubject_005falt_005fname"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_subject_alt_name</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_x509_subject_alt_name_t <var>nt</var>, const void * <var>data</var>, unsigned int <var>data_size</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crq</var>: a certificate request of type <code>gnutls_x509_crq_t</code> 
</p>
<p><var>nt</var>: is one of the <code>gnutls_x509_subject_alt_name_t</code>  enumerations
</p>
<p><var>data</var>: The data to be set
</p>
<p><var>data_size</var>: The size of data to be set
</p>
<p><var>flags</var>: <code>GNUTLS_FSAN_SET</code>  to clear previous data or
<code>GNUTLS_FSAN_APPEND</code>  to append.
</p>
<p>This function will set the subject alternative name certificate
extension.  It can set the following types:
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fversion-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_version</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fversion"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fversion"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_version</strong> <em>(gnutls_x509_crq_t <var>crq</var>, unsigned int <var>version</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>version</var>: holds the version number, for v1 Requests must be 1
</p>
<p>This function will set the version of the certificate request.  For
version 1 requests this must be one.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fsign2-1"></a>
<h4 class="subheading">gnutls_x509_crq_sign2</h4>
<a name="gnutls_005fx509_005fcrq_005fsign2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fsign2-1"></a>Function: <em>int</em> <strong>gnutls_x509_crq_sign2</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_x509_privkey_t <var>key</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>key</var>: holds a private key
</p>
<p><var>dig</var>: The message digest to use, i.e., <code>GNUTLS_DIG_SHA1</code> 
</p>
<p><var>flags</var>: must be 0
</p>
<p>This function will sign the certificate request with a private key.
This must be the same key as the one used in
<code>gnutls_x509_crt_set_key()</code>  since a certificate request is self
signed.
</p>
<p>This must be the last step in a certificate request generation
since all the previously set parameters are now signed.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
<code>GNUTLS_E_ASN1_VALUE_NOT_FOUND</code>  is returned if you didn&rsquo;t set all
information in the certificate request (e.g., the version using
<code>gnutls_x509_crq_set_version()</code> ).
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fverify-1"></a>
<h4 class="subheading">gnutls_x509_crq_verify</h4>
<a name="gnutls_005fx509_005fcrq_005fverify"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fverify"></a>Function: <em>int</em> <strong>gnutls_x509_crq_verify</strong> <em>(gnutls_x509_crq_t <var>crq</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crq</var>: is the crq to be verified
</p>
<p><var>flags</var>: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.
</p>
<p>This function will verify self signature in the certificate
request and return its status.
</p>
<p><strong>Returns:</strong> In case of a verification failure <code>GNUTLS_E_PK_SIG_VERIFY_FAILED</code>  
is returned, and zero or positive code on success.
</p>
<p>Since 2.12.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fcheck_005femail-1"></a>
<h4 class="subheading">gnutls_x509_crt_check_email</h4>
<a name="gnutls_005fx509_005fcrt_005fcheck_005femail"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fcheck_005femail"></a>Function: <em>int</em> <strong>gnutls_x509_crt_check_email</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const char * <var>email</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>cert</var>: should contain an gnutls_x509_crt_t type
</p>
<p><var>email</var>: A null terminated string that contains an email address (RFC822)
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will check if the given certificate&rsquo;s subject matches
the given email address.
</p>
<p><strong>Returns:</strong> non-zero for a successful match, and zero on failure.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fcheck_005fhostname-1"></a>
<h4 class="subheading">gnutls_x509_crt_check_hostname</h4>
<a name="gnutls_005fx509_005fcrt_005fcheck_005fhostname"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fcheck_005fhostname"></a>Function: <em>int</em> <strong>gnutls_x509_crt_check_hostname</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const char * <var>hostname</var>)</em></dt>
<dd><p><var>cert</var>: should contain an gnutls_x509_crt_t type
</p>
<p><var>hostname</var>: A null terminated string that contains a DNS name
</p>
<p>This function will check if the given certificate&rsquo;s subject matches
the given hostname.  This is a basic implementation of the matching
described in RFC6125, and takes into account wildcards,
and the DNSName/IPAddress subject alternative name PKIX extension.
</p>
<p>For details see also <code>gnutls_x509_crt_check_hostname2()</code> .
</p>
<p><strong>Returns:</strong> non-zero for a successful match, and zero on failure.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fcheck_005fhostname2-1"></a>
<h4 class="subheading">gnutls_x509_crt_check_hostname2</h4>
<a name="gnutls_005fx509_005fcrt_005fcheck_005fhostname2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fcheck_005fhostname2"></a>Function: <em>int</em> <strong>gnutls_x509_crt_check_hostname2</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const char * <var>hostname</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>cert</var>: should contain an gnutls_x509_crt_t type
</p>
<p><var>hostname</var>: A null terminated string that contains a DNS name
</p>
<p><var>flags</var>: gnutls_certificate_verify_flags
</p>
<p>This function will check if the given certificate&rsquo;s subject matches
the given hostname.  This is a basic implementation of the matching
described in RFC6125, and takes into account wildcards,
and the DNSName/IPAddress subject alternative name PKIX extension.
</p>
<p>IPv4 addresses are accepted by this function in the dotted-decimal
format (e.g, ddd.ddd.ddd.ddd), and IPv6 addresses in the hexadecimal
x:x:x:x:x:x:x:x format. For them the IPAddress subject alternative
name extension is consulted, as well as the DNSNames in case of a non-match.
The latter fallback exists due to misconfiguration of many servers
which place an IPAddress inside the DNSName extension.
</p>
<p>When the flag <code>GNUTLS_VERIFY_DO_NOT_ALLOW_WILDCARDS</code>  is specified no
wildcards are considered. Otherwise they are only considered if the
domain name consists of three components or more, and the wildcard
starts at the leftmost position.
</p>
<p><strong>Returns:</strong> non-zero for a successful match, and zero on failure.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fcheck_005fissuer-1"></a>
<h4 class="subheading">gnutls_x509_crt_check_issuer</h4>
<a name="gnutls_005fx509_005fcrt_005fcheck_005fissuer"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fcheck_005fissuer"></a>Function: <em>int</em> <strong>gnutls_x509_crt_check_issuer</strong> <em>(gnutls_x509_crt_t <var>cert</var>, gnutls_x509_crt_t <var>issuer</var>)</em></dt>
<dd><p><var>cert</var>: is the certificate to be checked
</p>
<p><var>issuer</var>: is the certificate of a possible issuer
</p>
<p>This function will check if the given certificate was issued by the
given issuer. It checks the DN fields and the authority
key identifier and subject key identifier fields match.
</p>
<p>If the same certificate is provided at the  <code>cert</code> and  <code>issuer</code> fields,
it will check whether the certificate is self-signed.
</p>
<p><strong>Returns:</strong> It will return true (1) if the given certificate is issued
by the given issuer, and false (0) if not.  
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fcheck_005frevocation-1"></a>
<h4 class="subheading">gnutls_x509_crt_check_revocation</h4>
<a name="gnutls_005fx509_005fcrt_005fcheck_005frevocation"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fcheck_005frevocation"></a>Function: <em>int</em> <strong>gnutls_x509_crt_check_revocation</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const gnutls_x509_crl_t * <var>crl_list</var>, int <var>crl_list_length</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>crl_list</var>: should contain a list of gnutls_x509_crl_t types
</p>
<p><var>crl_list_length</var>: the length of the crl_list
</p>
<p>This function will return check if the given certificate is
revoked.  It is assumed that the CRLs have been verified before.
</p>
<p><strong>Returns:</strong> 0 if the certificate is NOT revoked, and 1 if it is.  A
negative error code is returned on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fcpy_005fcrl_005fdist_005fpoints-1"></a>
<h4 class="subheading">gnutls_x509_crt_cpy_crl_dist_points</h4>
<a name="gnutls_005fx509_005fcrt_005fcpy_005fcrl_005fdist_005fpoints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fcpy_005fcrl_005fdist_005fpoints"></a>Function: <em>int</em> <strong>gnutls_x509_crt_cpy_crl_dist_points</strong> <em>(gnutls_x509_crt_t <var>dst</var>, gnutls_x509_crt_t <var>src</var>)</em></dt>
<dd><p><var>dst</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>src</var>: the certificate where the dist points will be copied from
</p>
<p>This function will copy the CRL distribution points certificate
extension, from the source to the destination certificate.
This may be useful to copy from a CA certificate to issued ones.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_crt_deinit</h4>
<a name="gnutls_005fx509_005fcrt_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_crt_deinit</strong> <em>(gnutls_x509_crt_t <var>cert</var>)</em></dt>
<dd><p><var>cert</var>: The data to be deinitialized
</p>
<p>This function will deinitialize a certificate structure.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fexport-1"></a>
<h4 class="subheading">gnutls_x509_crt_export</h4>
<a name="gnutls_005fx509_005fcrt_005fexport"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fexport"></a>Function: <em>int</em> <strong>gnutls_x509_crt_export</strong> <em>(gnutls_x509_crt_t <var>cert</var>, gnutls_x509_crt_fmt_t <var>format</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>cert</var>: Holds the certificate
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>output_data</var>: will contain a certificate PEM or DER encoded
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will export the certificate to DER or PEM format.
</p>
<p>If the buffer provided is not long enough to hold the output, then
*output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
be returned.
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN CERTIFICATE&quot;.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fexport2-1"></a>
<h4 class="subheading">gnutls_x509_crt_export2</h4>
<a name="gnutls_005fx509_005fcrt_005fexport2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fexport2"></a>Function: <em>int</em> <strong>gnutls_x509_crt_export2</strong> <em>(gnutls_x509_crt_t <var>cert</var>, gnutls_x509_crt_fmt_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>cert</var>: Holds the certificate
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>out</var>: will contain a certificate PEM or DER encoded
</p>
<p>This function will export the certificate to DER or PEM format.
The output buffer is allocated using <code>gnutls_malloc()</code> .
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN CERTIFICATE&quot;.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005factivation_005ftime-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_activation_time</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005factivation_005ftime"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005factivation_005ftime"></a>Function: <em>time_t</em> <strong>gnutls_x509_crt_get_activation_time</strong> <em>(gnutls_x509_crt_t <var>cert</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p>This function will return the time this Certificate was or will be
activated.
</p>
<p><strong>Returns:</strong> activation time, or (time_t)-1 on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fauthority_005finfo_005faccess-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_authority_info_access</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fauthority_005finfo_005faccess"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fauthority_005finfo_005faccess"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_authority_info_access</strong> <em>(gnutls_x509_crt_t <var>crt</var>, unsigned int <var>seq</var>, int <var>what</var>, gnutls_datum_t * <var>data</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>seq</var>: specifies the sequence number of the access descriptor (0 for the first one, 1 for the second etc.)
</p>
<p><var>what</var>: what data to get, a <code>gnutls_info_access_what_t</code>  type.
</p>
<p><var>data</var>: output data to be freed with <code>gnutls_free()</code> .
</p>
<p><var>critical</var>: pointer to output integer that is set to non-zero if the extension is marked as critical (may be <code>NULL</code> )
</p>
<p>Note that a simpler API to access the authority info data is provided
by <code>gnutls_x509_aia_get()</code>  and <code>gnutls_x509_ext_import_aia()</code> .
</p>
<p>This function extracts the Authority Information Access (AIA)
extension, see RFC 5280 section 4.2.2.1 for more information.  The
AIA extension holds a sequence of AccessDescription (AD) data.
</p>
<p>The  <code>seq</code> input parameter is used to indicate which member of the
sequence the caller is interested in.  The first member is 0, the
second member 1 and so on.  When the  <code>seq</code> value is out of bounds,
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p>
<p>The type of data returned in  <code>data</code> is specified via  <code>what</code> which
should be <code>gnutls_info_access_what_t</code>  values.
</p>
<p>If  <code>what</code> is <code>GNUTLS_IA_ACCESSMETHOD_OID</code>  then  <code>data</code> will hold the
accessMethod OID (e.g., &quot;1.3.6.1.5.5.7.48.1&quot;).
</p>
<p>If  <code>what</code> is <code>GNUTLS_IA_ACCESSLOCATION_GENERALNAME_TYPE</code> ,  <code>data</code> will
hold the accessLocation GeneralName type (e.g.,
&quot;uniformResourceIdentifier&quot;).
</p>
<p>If  <code>what</code> is <code>GNUTLS_IA_URI</code> ,  <code>data</code> will hold the accessLocation URI
data.  Requesting this  <code>what</code> value leads to an error if the
accessLocation is not of the &quot;uniformResourceIdentifier&quot; type. 
</p>
<p>If  <code>what</code> is <code>GNUTLS_IA_OCSP_URI</code> ,  <code>data</code> will hold the OCSP URI.
Requesting this  <code>what</code> value leads to an error if the accessMethod
is not 1.3.6.1.5.5.7.48.1 aka OSCP, or if accessLocation is not of
the &quot;uniformResourceIdentifier&quot; type. In that case <code>GNUTLS_E_UNKNOWN_ALGORITHM</code> 
will be returned, and  <code>seq</code> should be increased and this function
called again.
</p>
<p>If  <code>what</code> is <code>GNUTLS_IA_CAISSUERS_URI</code> ,  <code>data</code> will hold the caIssuers
URI.  Requesting this  <code>what</code> value leads to an error if the
accessMethod is not 1.3.6.1.5.5.7.48.2 aka caIssuers, or if
accessLocation is not of the &quot;uniformResourceIdentifier&quot; type.
In that case handle as in <code>GNUTLS_IA_OCSP_URI</code> .
</p>
<p>More  <code>what</code> values may be allocated in the future as needed.
</p>
<p>If  <code>data</code> is NULL, the function does the same without storing the
output data, that is, it will set  <code>critical</code> and do error checking
as usual.
</p>
<p>The value of the critical flag is returned in * <code>critical</code> .  Supply a
NULL  <code>critical</code> if you want the function to make sure the extension
is non-critical, as required by RFC 5280.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, <code>GNUTLS_E_INVALID_REQUEST</code>  on
invalid  <code>crt</code> , <code>GNUTLS_E_CONSTRAINT_ERROR</code>  if the extension is
incorrectly marked as critical (use a non-NULL  <code>critical</code> to
override), <code>GNUTLS_E_UNKNOWN_ALGORITHM</code>  if the requested OID does
not match (e.g., when using <code>GNUTLS_IA_OCSP_URI</code> ), otherwise a
negative error code.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fauthority_005fkey_005fgn_005fserial-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_authority_key_gn_serial</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fauthority_005fkey_005fgn_005fserial"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fauthority_005fkey_005fgn_005fserial"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_authority_key_gn_serial</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int <var>seq</var>, void * <var>alt</var>, size_t * <var>alt_size</var>, unsigned int * <var>alt_type</var>, void * <var>serial</var>, size_t * <var>serial_size</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>seq</var>: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
</p>
<p><var>alt</var>: is the place where the alternative name will be copied to
</p>
<p><var>alt_size</var>: holds the size of alt.
</p>
<p><var>alt_type</var>: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).
</p>
<p><var>serial</var>: buffer to store the serial number (may be null)
</p>
<p><var>serial_size</var>: Holds the size of the serial field (may be null)
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical (may be null)
</p>
<p>This function will return the X.509 authority key
identifier when stored as a general name (authorityCertIssuer) 
and serial number.
</p>
<p>Because more than one general names might be stored
 <code>seq</code> can be used as a counter to request them all until 
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the extension is not present, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fauthority_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_authority_key_id</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fauthority_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fauthority_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_authority_key_id</strong> <em>(gnutls_x509_crt_t <var>cert</var>, void * <var>id</var>, size_t * <var>id_size</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>id</var>: The place where the identifier will be copied
</p>
<p><var>id_size</var>: Holds the size of the id field.
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical (may be null)
</p>
<p>This function will return the X.509v3 certificate authority&rsquo;s key
identifier.  This is obtained by the X.509 Authority Key
identifier extension field (2.5.29.35). Note that this function
only returns the keyIdentifier field of the extension and
<code>GNUTLS_E_X509_UNSUPPORTED_EXTENSION</code> , if the extension contains
the name and serial number of the certificate. In that case
<code>gnutls_x509_crt_get_authority_key_gn_serial()</code>  may be used.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the extension is not present, otherwise a negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fbasic_005fconstraints-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_basic_constraints</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fbasic_005fconstraints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fbasic_005fconstraints"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_basic_constraints</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int * <var>critical</var>, unsigned int * <var>ca</var>, int * <var>pathlen</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
</p>
<p><var>ca</var>: pointer to output integer indicating CA status, may be NULL,
value is 1 if the certificate CA flag is set, 0 otherwise.
</p>
<p><var>pathlen</var>: pointer to output integer indicating path length (may be
NULL), non-negative error codes indicate a present pathLenConstraint
field and the actual value, -1 indicate that the field is absent.
</p>
<p>This function will read the certificate&rsquo;s basic constraints, and
return the certificates CA status.  It reads the basicConstraints
X.509 extension (2.5.29.19).
</p>
<p><strong>Returns:</strong> If the certificate is a CA a positive value will be
returned, or (0) if the certificate does not have CA flag set.  A
negative error code may be returned in case of errors.  If the
certificate does not contain the basicConstraints extension
GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fca_005fstatus-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_ca_status</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fca_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fca_005fstatus"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_ca_status</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
</p>
<p>This function will return certificates CA status, by reading the
basicConstraints X.509 extension (2.5.29.19). If the certificate is
a CA a positive value will be returned, or (0) if the certificate
does not have CA flag set.
</p>
<p>Use <code>gnutls_x509_crt_get_basic_constraints()</code>  if you want to read the
pathLenConstraint field too.
</p>
<p><strong>Returns:</strong> If the certificate is a CA a positive value will be
returned, or (0) if the certificate does not have CA flag set.  A
negative error code may be returned in case of errors.  If the
certificate does not contain the basicConstraints extension
GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fcrl_005fdist_005fpoints-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_crl_dist_points</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fcrl_005fdist_005fpoints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fcrl_005fdist_005fpoints"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_crl_dist_points</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int <var>seq</var>, void * <var>san</var>, size_t * <var>san_size</var>, unsigned int * <var>reason_flags</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>seq</var>: specifies the sequence number of the distribution point (0 for the first one, 1 for the second etc.)
</p>
<p><var>san</var>: is the place where the distribution point will be copied to
</p>
<p><var>san_size</var>: holds the size of ret.
</p>
<p><var>reason_flags</var>: Revocation reasons. An ORed sequence of flags from <code>gnutls_x509_crl_reason_flags_t</code> .
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical (may be null)
</p>
<p>This function retrieves the CRL distribution points (2.5.29.31),
contained in the given certificate in the X509v3 Certificate
Extensions.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  and updates  <code>ret_size</code> if
 <code>ret_size</code> is not enough to hold the distribution point, or the
type of the distribution point if everything was ok. The type is
one of the enumerated <code>gnutls_x509_subject_alt_name_t</code> .  If the
certificate does not have an Alternative name with the specified
sequence number then <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is
returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fdn-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_dn</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fdn"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fdn"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_dn</strong> <em>(gnutls_x509_crt_t <var>cert</var>, char * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>buf</var>: a pointer to a structure to hold the name (may be null)
</p>
<p><var>buf_size</var>: initially holds the size of  <code>buf</code> 
</p>
<p>This function will copy the name of the Certificate in the provided
buffer. The name will be in the form &quot;C=xxxx,O=yyyy,CN=zzzz&quot; as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.
</p>
<p>If  <code>buf</code> is null then only the size will be filled. 
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is not
long enough, and in that case the  <code>buf_size</code> will be updated
with the required size.  On success 0 is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fdn2-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_dn2</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fdn2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fdn2-1"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_dn2</strong> <em>(gnutls_x509_crt_t <var>cert</var>, gnutls_datum_t * <var>dn</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>dn</var>: a pointer to a structure to hold the name
</p>
<p>This function will allocate buffer and copy the name of the Certificate.
The name will be in the form &quot;C=xxxx,O=yyyy,CN=zzzz&quot; as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.10
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fdn_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_dn_by_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fdn_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fdn_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_dn_by_oid</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const char * <var>oid</var>, int <var>indx</var>, unsigned int <var>raw_flag</var>, void * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>oid</var>: holds an Object Identified in null terminated string
</p>
<p><var>indx</var>: In case multiple same OIDs exist in the RDN, this specifies which to send. Use (0) to get the first one.
</p>
<p><var>raw_flag</var>: If non-zero returns the raw DER data of the DN part.
</p>
<p><var>buf</var>: a pointer where the DN part will be copied (may be null).
</p>
<p><var>buf_size</var>: initially holds the size of  <code>buf</code> 
</p>
<p>This function will extract the part of the name of the Certificate
subject specified by the given OID. The output, if the raw flag is
not used, will be encoded as described in RFC4514. Thus a string
that is ASCII or UTF-8 encoded, depending on the certificate data.
</p>
<p>Some helper macros with popular OIDs can be found in gnutls/x509.h
If raw flag is (0), this function will only return known OIDs as
text. Other OIDs will be DER encoded, as described in RFC4514 &ndash;
in hex format with a &rsquo;#&rsquo; prefix.  You can check about known OIDs
using <code>gnutls_x509_dn_oid_known()</code> .
</p>
<p>If  <code>buf</code> is null then only the size will be filled. If the  <code>raw_flag</code> is not specified the output is always null terminated, although the
 <code>buf_size</code> will not include the null character.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is not
long enough, and in that case the  <code>buf_size</code> will be updated with
the required size. <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  if there 
are no data in the current index. On success 0 is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fdn_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_dn_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fdn_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fdn_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_dn_oid</strong> <em>(gnutls_x509_crt_t <var>cert</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>oid_size</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>indx</var>: This specifies which OID to return. Use (0) to get the first one.
</p>
<p><var>oid</var>: a pointer to a buffer to hold the OID (may be null)
</p>
<p><var>oid_size</var>: initially holds the size of  <code>oid</code> 
</p>
<p>This function will extract the OIDs of the name of the Certificate
subject specified by the given index.
</p>
<p>If  <code>oid</code> is null then only the size will be filled. The  <code>oid</code> returned will be null terminated, although  <code>oid_size</code> will not
account for the trailing null.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is not
long enough, and in that case the  <code>buf_size</code> will be updated with
the required size. <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  if there 
are no data in the current index. On success 0 is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fexpiration_005ftime-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_expiration_time</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fexpiration_005ftime"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fexpiration_005ftime"></a>Function: <em>time_t</em> <strong>gnutls_x509_crt_get_expiration_time</strong> <em>(gnutls_x509_crt_t <var>cert</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p>This function will return the time this Certificate was or will be
expired.
</p>
<p>The no well defined expiration time can be checked against with the
<code>GNUTLS_X509_NO_WELL_DEFINED_EXPIRATION</code>  macro.
</p>
<p><strong>Returns:</strong> expiration time, or (time_t)-1 on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fextension_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_extension_by_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fextension_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fextension_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_extension_by_oid</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const char * <var>oid</var>, int <var>indx</var>, void * <var>buf</var>, size_t * <var>buf_size</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>oid</var>: holds an Object Identified in null terminated string
</p>
<p><var>indx</var>: In case multiple same OIDs exist in the extensions, this specifies which to send. Use (0) to get the first one.
</p>
<p><var>buf</var>: a pointer to a structure to hold the name (may be null)
</p>
<p><var>buf_size</var>: initially holds the size of  <code>buf</code> 
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
</p>
<p>This function will return the extension specified by the OID in the
certificate.  The extensions will be returned as binary data DER
encoded, in the provided buffer.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned. If the certificate does not
contain the specified extension
GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fextension_005fby_005foid2-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_extension_by_oid2</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fextension_005fby_005foid2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fextension_005fby_005foid2"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_extension_by_oid2</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const char * <var>oid</var>, int <var>indx</var>, gnutls_datum_t * <var>output</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>oid</var>: holds an Object Identified in null terminated string
</p>
<p><var>indx</var>: In case multiple same OIDs exist in the extensions, this specifies which to send. Use (0) to get the first one.
</p>
<p><var>output</var>: will hold the allocated extension data
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
</p>
<p>This function will return the extension specified by the OID in the
certificate.  The extensions will be returned as binary data DER
encoded, in the provided buffer.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned. If the certificate does not
contain the specified extension
GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
</p>
<p><strong>Since:</strong> 3.3.8
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fextension_005fdata-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_extension_data</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fextension_005fdata"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fextension_005fdata"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_extension_data</strong> <em>(gnutls_x509_crt_t <var>cert</var>, int <var>indx</var>, void * <var>data</var>, size_t * <var>sizeof_data</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension OID to send. Use (0) to get the first one.
</p>
<p><var>data</var>: a pointer to a structure to hold the data (may be null)
</p>
<p><var>sizeof_data</var>: initially holds the size of  <code>data</code> 
</p>
<p>This function will return the requested extension data in the
certificate.  The extension data will be stored in the
provided buffer.
</p>
<p>Use <code>gnutls_x509_crt_get_extension_info()</code>  to extract the OID and
critical flag.  Use <code>gnutls_x509_crt_get_extension_by_oid()</code>  instead,
if you want to get data indexed by the extension OID rather than
sequence.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.  If you have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fextension_005fdata2-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_extension_data2</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fextension_005fdata2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fextension_005fdata2"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_extension_data2</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned <var>indx</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension OID to read. Use (0) to get the first one.
</p>
<p><var>data</var>: will contain the extension DER-encoded data
</p>
<p>This function will return the requested by the index extension data in the
certificate.  The extension data will be allocated using
<code>gnutls_malloc()</code> .
</p>
<p>Use <code>gnutls_x509_crt_get_extension_info()</code>  to extract the OID.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.  If you have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fextension_005finfo-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_extension_info</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fextension_005finfo"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fextension_005finfo"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_extension_info</strong> <em>(gnutls_x509_crt_t <var>cert</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>oid_size</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension OID to send. Use (0) to get the first one.
</p>
<p><var>oid</var>: a pointer to a structure to hold the OID
</p>
<p><var>oid_size</var>: initially holds the maximum size of  <code>oid</code> , on return
holds actual size of  <code>oid</code> .
</p>
<p><var>critical</var>: output variable with critical flag, may be NULL.
</p>
<p>This function will return the requested extension OID in the
certificate, and the critical flag for it.  The extension OID will
be stored as a string in the provided buffer.  Use
<code>gnutls_x509_crt_get_extension()</code>  to extract the data.
</p>
<p>If the buffer provided is not long enough to hold the output, then
 <code>oid_size</code> is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  will be
returned. The  <code>oid</code> returned will be null terminated, although 
 <code>oid_size</code> will not account for the trailing null.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.  If you have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fextension_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_extension_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fextension_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fextension_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_extension_oid</strong> <em>(gnutls_x509_crt_t <var>cert</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>oid_size</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension OID to send. Use (0) to get the first one.
</p>
<p><var>oid</var>: a pointer to a structure to hold the OID (may be null)
</p>
<p><var>oid_size</var>: initially holds the size of  <code>oid</code> 
</p>
<p>This function will return the requested extension OID in the certificate.
The extension OID will be stored as a string in the provided buffer.
</p>
<p>The  <code>oid</code> returned will be null terminated, although  <code>oid_size</code> will not
account for the trailing null.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.  If you have reached the
last extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
will be returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005ffingerprint-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_fingerprint</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005ffingerprint"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005ffingerprint"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_fingerprint</strong> <em>(gnutls_x509_crt_t <var>cert</var>, gnutls_digest_algorithm_t <var>algo</var>, void * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>algo</var>: is a digest algorithm
</p>
<p><var>buf</var>: a pointer to a structure to hold the fingerprint (may be null)
</p>
<p><var>buf_size</var>: initially holds the size of  <code>buf</code> 
</p>
<p>This function will calculate and copy the certificate&rsquo;s fingerprint
in the provided buffer. The fingerprint is a hash of the DER-encoded
data of the certificate.
</p>
<p>If the buffer is null then only the size will be filled.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is
not long enough, and in that case the *buf_size will be updated
with the required size.  On success 0 is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fissuer-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_issuer</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fissuer"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fissuer"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_issuer</strong> <em>(gnutls_x509_crt_t <var>cert</var>, gnutls_x509_dn_t * <var>dn</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>dn</var>: output variable with pointer to uint8_t DN
</p>
<p>Return the Certificate&rsquo;s Issuer DN as a <code>gnutls_x509_dn_t</code>  data type,
that can be decoded using <code>gnutls_x509_dn_get_rdn_ava()</code> . 
</p>
<p>Note that  <code>dn</code> should be treated as constant. Because it points 
into the  <code>cert</code> object, you should not use  <code>dn</code> after  <code>cert</code> is
deallocated.
</p>
<p><strong>Returns:</strong> Returns 0 on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005falt_005fname-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_issuer_alt_name</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005falt_005fname"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fissuer_005falt_005fname"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_issuer_alt_name</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int <var>seq</var>, void * <var>ian</var>, size_t * <var>ian_size</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>seq</var>: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
</p>
<p><var>ian</var>: is the place where the alternative name will be copied to
</p>
<p><var>ian_size</var>: holds the size of ian.
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical (may be null)
</p>
<p>This function retrieves the Issuer Alternative Name (2.5.29.18),
contained in the given certificate in the X509v3 Certificate
Extensions.
</p>
<p>When the SAN type is otherName, it will extract the data in the
otherName&rsquo;s value field, and <code>GNUTLS_SAN_OTHERNAME</code>  is returned.
You may use <code>gnutls_x509_crt_get_subject_alt_othername_oid()</code>  to get
the corresponding OID and the &quot;virtual&quot; SAN types (e.g.,
<code>GNUTLS_SAN_OTHERNAME_XMPP</code> ).
</p>
<p>If an otherName OID is known, the data will be decoded.  Otherwise
the returned data will be DER encoded, and you will have to decode
it yourself.  Currently, only the RFC 3920 id-on-xmppAddr Issuer
AltName is recognized.
</p>
<p><strong>Returns:</strong> the alternative issuer name type on success, one of the
enumerated <code>gnutls_x509_subject_alt_name_t</code> .  It will return
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if  <code>ian_size</code> is not large enough
to hold the value.  In that case  <code>ian_size</code> will be updated with
the required size.  If the certificate does not have an
Alternative name with the specified sequence number then
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005falt_005fname2-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_issuer_alt_name2</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005falt_005fname2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fissuer_005falt_005fname2"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_issuer_alt_name2</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int <var>seq</var>, void * <var>ian</var>, size_t * <var>ian_size</var>, unsigned int * <var>ian_type</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>seq</var>: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
</p>
<p><var>ian</var>: is the place where the alternative name will be copied to
</p>
<p><var>ian_size</var>: holds the size of ret.
</p>
<p><var>ian_type</var>: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical (may be null)
</p>
<p>This function will return the alternative names, contained in the
given certificate. It is the same as
<code>gnutls_x509_crt_get_issuer_alt_name()</code>  except for the fact that it
will return the type of the alternative name in  <code>ian_type</code> even if
the function fails for some reason (i.e.  the buffer provided is
not enough).
</p>
<p><strong>Returns:</strong> the alternative issuer name type on success, one of the
enumerated <code>gnutls_x509_subject_alt_name_t</code> .  It will return
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if  <code>ian_size</code> is not large enough
to hold the value.  In that case  <code>ian_size</code> will be updated with
the required size.  If the certificate does not have an
Alternative name with the specified sequence number then
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005falt_005fothername_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_issuer_alt_othername_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005falt_005fothername_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fissuer_005falt_005fothername_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_issuer_alt_othername_oid</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int <var>seq</var>, void * <var>ret</var>, size_t * <var>ret_size</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>seq</var>: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
</p>
<p><var>ret</var>: is the place where the otherName OID will be copied to
</p>
<p><var>ret_size</var>: holds the size of ret.
</p>
<p>This function will extract the type OID of an otherName Subject
Alternative Name, contained in the given certificate, and return
the type as an enumerated element.
</p>
<p>If  <code>oid</code> is null then only the size will be filled. The  <code>oid</code> returned will be null terminated, although  <code>oid_size</code> will not
account for the trailing null.
</p>
<p>This function is only useful if
<code>gnutls_x509_crt_get_issuer_alt_name()</code>  returned
<code>GNUTLS_SAN_OTHERNAME</code> .
</p>
<p><strong>Returns:</strong> the alternative issuer name type on success, one of the
enumerated gnutls_x509_subject_alt_name_t.  For supported OIDs, it
will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types,
e.g. <code>GNUTLS_SAN_OTHERNAME_XMPP</code> , and <code>GNUTLS_SAN_OTHERNAME</code>  for
unknown OIDs.  It will return <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if
 <code>ret_size</code> is not large enough to hold the value.  In that case
 <code>ret_size</code> will be updated with the required size.  If the
certificate does not have an Alternative name with the specified
sequence number and with the otherName type then
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_issuer_dn</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_issuer_dn</strong> <em>(gnutls_x509_crt_t <var>cert</var>, char * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>buf</var>: a pointer to a structure to hold the name (may be null)
</p>
<p><var>buf_size</var>: initially holds the size of  <code>buf</code> 
</p>
<p>This function will copy the name of the Certificate issuer in the
provided buffer. The name will be in the form
&quot;C=xxxx,O=yyyy,CN=zzzz&quot; as described in RFC4514. The output string
will be ASCII or UTF-8 encoded, depending on the certificate data.
</p>
<p>If  <code>buf</code> is null then only the size will be filled. 
</p>
<p><strong>Returns:</strong> GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not
long enough, and in that case the  <code>buf_size</code> will be updated with
the required size.  On success 0 is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn2-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_issuer_dn2</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn2"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_issuer_dn2</strong> <em>(gnutls_x509_crt_t <var>cert</var>, gnutls_datum_t * <var>dn</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>dn</var>: a pointer to a structure to hold the name
</p>
<p>This function will allocate buffer and copy the name of issuer of the Certificate.
The name will be in the form &quot;C=xxxx,O=yyyy,CN=zzzz&quot; as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.10
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_issuer_dn_by_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_issuer_dn_by_oid</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const char * <var>oid</var>, int <var>indx</var>, unsigned int <var>raw_flag</var>, void * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>oid</var>: holds an Object Identified in null terminated string
</p>
<p><var>indx</var>: In case multiple same OIDs exist in the RDN, this specifies which to send. Use (0) to get the first one.
</p>
<p><var>raw_flag</var>: If non-zero returns the raw DER data of the DN part.
</p>
<p><var>buf</var>: a pointer to a structure to hold the name (may be null)
</p>
<p><var>buf_size</var>: initially holds the size of  <code>buf</code> 
</p>
<p>This function will extract the part of the name of the Certificate
issuer specified by the given OID. The output, if the raw flag is not
used, will be encoded as described in RFC4514. Thus a string that is
ASCII or UTF-8 encoded, depending on the certificate data.
</p>
<p>Some helper macros with popular OIDs can be found in gnutls/x509.h
If raw flag is (0), this function will only return known OIDs as
text. Other OIDs will be DER encoded, as described in RFC4514 &ndash;
in hex format with a &rsquo;#&rsquo; prefix.  You can check about known OIDs
using <code>gnutls_x509_dn_oid_known()</code> .
</p>
<p>If  <code>buf</code> is null then only the size will be filled. If the  <code>raw_flag</code> is not specified the output is always null terminated, although the
 <code>buf_size</code> will not include the null character.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is not
long enough, and in that case the  <code>buf_size</code> will be updated with
the required size. <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  if there 
are no data in the current index. On success 0 is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_issuer_dn_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_issuer_dn_oid</strong> <em>(gnutls_x509_crt_t <var>cert</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>oid_size</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>indx</var>: This specifies which OID to return. Use (0) to get the first one.
</p>
<p><var>oid</var>: a pointer to a buffer to hold the OID (may be null)
</p>
<p><var>oid_size</var>: initially holds the size of  <code>oid</code> 
</p>
<p>This function will extract the OIDs of the name of the Certificate
issuer specified by the given index.
</p>
<p>If  <code>oid</code> is null then only the size will be filled. The  <code>oid</code> returned will be null terminated, although  <code>oid_size</code> will not
account for the trailing null.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is not
long enough, and in that case the  <code>buf_size</code> will be updated with
the required size. <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  if there 
are no data in the current index. On success 0 is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005funique_005fid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_issuer_unique_id</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fissuer_005funique_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fissuer_005funique_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_issuer_unique_id</strong> <em>(gnutls_x509_crt_t <var>crt</var>, char * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>buf</var>: user allocated memory buffer, will hold the unique id
</p>
<p><var>buf_size</var>: size of user allocated memory buffer (on input), will hold
actual size of the unique ID on return.
</p>
<p>This function will extract the issuerUniqueID value (if present) for
the given certificate.
</p>
<p>If the user allocated memory buffer is not large enough to hold the
full subjectUniqueID, then a GNUTLS_E_SHORT_MEMORY_BUFFER error will be
returned, and buf_size will be set to the actual length.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_key_id</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fkey_005fid-1"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_key_id</strong> <em>(gnutls_x509_crt_t <var>crt</var>, unsigned int <var>flags</var>, unsigned char * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>flags</var>: should be one of the flags from <code>gnutls_keyid_flags_t</code> 
</p>
<p><var>output_data</var>: will contain the key ID
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will return a unique ID that depends on the public
key parameters. This ID can be used in checking whether a
certificate corresponds to the given private key.
</p>
<p>If the buffer provided is not long enough to hold the output, then
*output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
be returned.  The output will normally be a SHA-1 hash output,
which is 20 bytes.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fkey_005fpurpose_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_key_purpose_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fkey_005fpurpose_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fkey_005fpurpose_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_key_purpose_oid</strong> <em>(gnutls_x509_crt_t <var>cert</var>, int <var>indx</var>, void * <var>oid</var>, size_t * <var>oid_size</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>indx</var>: This specifies which OID to return. Use (0) to get the first one.
</p>
<p><var>oid</var>: a pointer to a buffer to hold the OID (may be null)
</p>
<p><var>oid_size</var>: initially holds the size of  <code>oid</code> 
</p>
<p><var>critical</var>: output flag to indicate criticality of extension
</p>
<p>This function will extract the key purpose OIDs of the Certificate
specified by the given index.  These are stored in the Extended Key
Usage extension (2.5.29.37) See the GNUTLS_KP_* definitions for
human readable names.
</p>
<p>If  <code>oid</code> is null then only the size will be filled. The  <code>oid</code> returned will be null terminated, although  <code>oid_size</code> will not
account for the trailing null.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if the provided buffer is
not long enough, and in that case the *oid_size will be updated
with the required size.  On success 0 is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fkey_005fusage-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_key_usage</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fkey_005fusage"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fkey_005fusage"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_key_usage</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int * <var>key_usage</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>key_usage</var>: where the key usage bits will be stored
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
</p>
<p>This function will return certificate&rsquo;s key usage, by reading the
keyUsage X.509 extension (2.5.29.15). The key usage value will ORed
values of the: <code>GNUTLS_KEY_DIGITAL_SIGNATURE</code> ,
<code>GNUTLS_KEY_NON_REPUDIATION</code> , <code>GNUTLS_KEY_KEY_ENCIPHERMENT</code> ,
<code>GNUTLS_KEY_DATA_ENCIPHERMENT</code> , <code>GNUTLS_KEY_KEY_AGREEMENT</code> ,
<code>GNUTLS_KEY_KEY_CERT_SIGN</code> , <code>GNUTLS_KEY_CRL_SIGN</code> ,
<code>GNUTLS_KEY_ENCIPHER_ONLY</code> , <code>GNUTLS_KEY_DECIPHER_ONLY</code> .
</p>
<p><strong>Returns:</strong> the certificate key usage, or a negative error code in case of
parsing error.  If the certificate does not contain the keyUsage
extension <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be
returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fname_005fconstraints-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_name_constraints</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fname_005fconstraints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fname_005fconstraints"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_name_constraints</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_name_constraints_t <var>nc</var>, unsigned int <var>flags</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crt</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>nc</var>: The nameconstraints intermediate type
</p>
<p><var>flags</var>: zero or <code>GNUTLS_NAME_CONSTRAINTS_FLAG_APPEND</code> 
</p>
<p><var>critical</var>: the extension status
</p>
<p>This function will return an intermediate type containing
the name constraints of the provided CA certificate. That
structure can be used in combination with <code>gnutls_x509_name_constraints_check()</code> 
to verify whether a server&rsquo;s name is in accordance with the constraints.
</p>
<p>When the  <code>flags</code> is set to <code>GNUTLS_NAME_CONSTRAINTS_FLAG_APPEND</code> , then if 
the  <code>nc</code> structure is empty
this function will behave identically as if the flag was not set.
Otherwise if there are elements in the  <code>nc</code> structure then only the
excluded constraints will be appended to the constraints.
</p>
<p>Note that  <code>nc</code> must be initialized prior to calling this function.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the extension is not present, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fpk_005falgorithm-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_pk_algorithm</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fpk_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fpk_005falgorithm"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_pk_algorithm</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int * <var>bits</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>bits</var>: if bits is non null it will hold the size of the parameters&rsquo; in bits
</p>
<p>This function will return the public key algorithm of an X.509
certificate.
</p>
<p>If bits is non null, it should have enough size to hold the parameters
size in bits. For RSA the bits returned is the modulus.
For DSA the bits returned are of the public
exponent.
</p>
<p><strong>Returns:</strong> a member of the <code>gnutls_pk_algorithm_t</code>  enumeration on
success, or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fpk_005fdsa_005fraw-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_pk_dsa_raw</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fpk_005fdsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fpk_005fdsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_pk_dsa_raw</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>g</var>, gnutls_datum_t * <var>y</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>p</var>: will hold the p
</p>
<p><var>q</var>: will hold the q
</p>
<p><var>g</var>: will hold the g
</p>
<p><var>y</var>: will hold the y
</p>
<p>This function will export the DSA public key&rsquo;s parameters found in
the given certificate.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fpk_005fecc_005fraw-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_pk_ecc_raw</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fpk_005fecc_005fraw"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fpk_005fecc_005fraw"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_pk_ecc_raw</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_ecc_curve_t * <var>curve</var>, gnutls_datum_t * <var>x</var>, gnutls_datum_t * <var>y</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>curve</var>: will hold the curve
</p>
<p><var>x</var>: will hold x
</p>
<p><var>y</var>: will hold y
</p>
<p>This function will export the ECC public key&rsquo;s parameters found in
the given certificate.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.1
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fpk_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_pk_rsa_raw</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fpk_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fpk_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_pk_rsa_raw</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_datum_t * <var>m</var>, gnutls_datum_t * <var>e</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>m</var>: will hold the modulus
</p>
<p><var>e</var>: will hold the public exponent
</p>
<p>This function will export the RSA public key&rsquo;s parameters found in
the given structure.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fpolicy-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_policy</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fpolicy"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fpolicy"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_policy</strong> <em>(gnutls_x509_crt_t <var>crt</var>, int <var>indx</var>, struct gnutls_x509_policy_st * <var>policy</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>crt</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>indx</var>: This specifies which policy to return. Use (0) to get the first one.
</p>
<p><var>policy</var>: A pointer to a policy structure.
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
</p>
<p>This function will extract the certificate policy (extension 2.5.29.32) 
specified by the given index. 
</p>
<p>The policy returned by this function must be deinitialized by using
<code>gnutls_x509_policy_release()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the extension is not present, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.1.5
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fprivate_005fkey_005fusage_005fperiod-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_private_key_usage_period</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fprivate_005fkey_005fusage_005fperiod"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fprivate_005fkey_005fusage_005fperiod"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_private_key_usage_period</strong> <em>(gnutls_x509_crt_t <var>cert</var>, time_t * <var>activation</var>, time_t * <var>expiration</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>activation</var>: The activation time
</p>
<p><var>expiration</var>: The expiration time
</p>
<p><var>critical</var>: the extension status
</p>
<p>This function will return the expiration and activation
times of the private key of the certificate. It relies on
the PKIX extension 2.5.29.16 being present.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the extension is not present, otherwise a negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fproxy-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_proxy</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fproxy"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fproxy"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_proxy</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int * <var>critical</var>, int * <var>pathlen</var>, char ** <var>policyLanguage</var>, char ** <var>policy</var>, size_t * <var>sizeof_policy</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical
</p>
<p><var>pathlen</var>: pointer to output integer indicating path length (may be
NULL), non-negative error codes indicate a present pCPathLenConstraint
field and the actual value, -1 indicate that the field is absent.
</p>
<p><var>policyLanguage</var>: output variable with OID of policy language
</p>
<p><var>policy</var>: output variable with policy data
</p>
<p><var>sizeof_policy</var>: output variable size of policy data
</p>
<p>This function will get information from a proxy certificate.  It
reads the ProxyCertInfo X.509 extension (1.3.6.1.5.5.7.1.14).
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fraw_005fdn-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_raw_dn</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fraw_005fdn"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fraw_005fdn"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_raw_dn</strong> <em>(gnutls_x509_crt_t <var>cert</var>, gnutls_datum_t * <var>dn</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>dn</var>: will hold the starting point of the DN
</p>
<p>This function will return a pointer to the DER encoded DN structure and
the length. This points to allocated data that must be free&rsquo;d using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fraw_005fissuer_005fdn-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_raw_issuer_dn</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fraw_005fissuer_005fdn"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fraw_005fissuer_005fdn"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_raw_issuer_dn</strong> <em>(gnutls_x509_crt_t <var>cert</var>, gnutls_datum_t * <var>dn</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>dn</var>: will hold the starting point of the DN
</p>
<p>This function will return a pointer to the DER encoded DN structure
and the length. This points to allocated data that must be free&rsquo;d using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fserial-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_serial</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fserial"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fserial"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_serial</strong> <em>(gnutls_x509_crt_t <var>cert</var>, void * <var>result</var>, size_t * <var>result_size</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>result</var>: The place where the serial number will be copied
</p>
<p><var>result_size</var>: Holds the size of the result field.
</p>
<p>This function will return the X.509 certificate&rsquo;s serial number.
This is obtained by the X509 Certificate serialNumber field. Serial
is not always a 32 or 64bit number. Some CAs use large serial
numbers, thus it may be wise to handle it as something uint8_t.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fsignature-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_signature</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fsignature"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fsignature"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_signature</strong> <em>(gnutls_x509_crt_t <var>cert</var>, char * <var>sig</var>, size_t * <var>sig_size</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>sig</var>: a pointer where the signature part will be copied (may be null).
</p>
<p><var>sig_size</var>: initially holds the size of  <code>sig</code> 
</p>
<p>This function will extract the signature field of a certificate.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fsignature_005falgorithm-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_signature_algorithm</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fsignature_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fsignature_005falgorithm"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_signature_algorithm</strong> <em>(gnutls_x509_crt_t <var>cert</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p>This function will return a value of the <code>gnutls_sign_algorithm_t</code> 
enumeration that is the signature algorithm that has been used to
sign this certificate.
</p>
<p><strong>Returns:</strong> a <code>gnutls_sign_algorithm_t</code>  value, or a negative error code on
error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fsubject-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_subject</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fsubject"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fsubject"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_subject</strong> <em>(gnutls_x509_crt_t <var>cert</var>, gnutls_x509_dn_t * <var>dn</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>dn</var>: output variable with pointer to uint8_t DN.
</p>
<p>Return the Certificate&rsquo;s Subject DN as a <code>gnutls_x509_dn_t</code>  data type,
that can be decoded using <code>gnutls_x509_dn_get_rdn_ava()</code> . 
</p>
<p>Note that  <code>dn</code> should be treated as constant. Because it points 
into the  <code>cert</code> object, you should not use  <code>dn</code> after  <code>cert</code> is
deallocated.
</p>
<p><strong>Returns:</strong> Returns 0 on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fname-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_subject_alt_name</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fname"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fname"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_subject_alt_name</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int <var>seq</var>, void * <var>san</var>, size_t * <var>san_size</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>seq</var>: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
</p>
<p><var>san</var>: is the place where the alternative name will be copied to
</p>
<p><var>san_size</var>: holds the size of san.
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical (may be null)
</p>
<p>This function retrieves the Alternative Name (2.5.29.17), contained
in the given certificate in the X509v3 Certificate Extensions.
</p>
<p>When the SAN type is otherName, it will extract the data in the
otherName&rsquo;s value field, and <code>GNUTLS_SAN_OTHERNAME</code>  is returned.
You may use <code>gnutls_x509_crt_get_subject_alt_othername_oid()</code>  to get
the corresponding OID and the &quot;virtual&quot; SAN types (e.g.,
<code>GNUTLS_SAN_OTHERNAME_XMPP</code> ).
</p>
<p>If an otherName OID is known, the data will be decoded.  Otherwise
the returned data will be DER encoded, and you will have to decode
it yourself.  Currently, only the RFC 3920 id-on-xmppAddr SAN is
recognized.
</p>
<p><strong>Returns:</strong> the alternative subject name type on success, one of the
enumerated <code>gnutls_x509_subject_alt_name_t</code> .  It will return
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if  <code>san_size</code> is not large enough to
hold the value.  In that case  <code>san_size</code> will be updated with the
required size.  If the certificate does not have an Alternative
name with the specified sequence number then
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fname2-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_subject_alt_name2</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fname2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fname2"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_subject_alt_name2</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int <var>seq</var>, void * <var>san</var>, size_t * <var>san_size</var>, unsigned int * <var>san_type</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>seq</var>: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
</p>
<p><var>san</var>: is the place where the alternative name will be copied to
</p>
<p><var>san_size</var>: holds the size of ret.
</p>
<p><var>san_type</var>: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical (may be null)
</p>
<p>This function will return the alternative names, contained in the
given certificate. It is the same as
<code>gnutls_x509_crt_get_subject_alt_name()</code>  except for the fact that it
will return the type of the alternative name in  <code>san_type</code> even if
the function fails for some reason (i.e.  the buffer provided is
not enough).
</p>
<p><strong>Returns:</strong> the alternative subject name type on success, one of the
enumerated <code>gnutls_x509_subject_alt_name_t</code> .  It will return
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if  <code>san_size</code> is not large enough
to hold the value.  In that case  <code>san_size</code> will be updated with
the required size.  If the certificate does not have an
Alternative name with the specified sequence number then
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fothername_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_subject_alt_othername_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fothername_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fothername_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_subject_alt_othername_oid</strong> <em>(gnutls_x509_crt_t <var>cert</var>, unsigned int <var>seq</var>, void * <var>oid</var>, size_t * <var>oid_size</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>seq</var>: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
</p>
<p><var>oid</var>: is the place where the otherName OID will be copied to
</p>
<p><var>oid_size</var>: holds the size of ret.
</p>
<p>This function will extract the type OID of an otherName Subject
Alternative Name, contained in the given certificate, and return
the type as an enumerated element.
</p>
<p>This function is only useful if
<code>gnutls_x509_crt_get_subject_alt_name()</code>  returned
<code>GNUTLS_SAN_OTHERNAME</code> .
</p>
<p>If  <code>oid</code> is null then only the size will be filled. The  <code>oid</code> returned will be null terminated, although  <code>oid_size</code> will not
account for the trailing null.
</p>
<p><strong>Returns:</strong> the alternative subject name type on success, one of the
enumerated gnutls_x509_subject_alt_name_t.  For supported OIDs, it
will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types,
e.g. <code>GNUTLS_SAN_OTHERNAME_XMPP</code> , and <code>GNUTLS_SAN_OTHERNAME</code>  for
unknown OIDs.  It will return <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  if
 <code>ian_size</code> is not large enough to hold the value.  In that case
 <code>ian_size</code> will be updated with the required size.  If the
certificate does not have an Alternative name with the specified
sequence number and with the otherName type then
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fsubject_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_subject_key_id</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fsubject_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fsubject_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_subject_key_id</strong> <em>(gnutls_x509_crt_t <var>cert</var>, void * <var>ret</var>, size_t * <var>ret_size</var>, unsigned int * <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>ret</var>: The place where the identifier will be copied
</p>
<p><var>ret_size</var>: Holds the size of the result field.
</p>
<p><var>critical</var>: will be non-zero if the extension is marked as critical (may be null)
</p>
<p>This function will return the X.509v3 certificate&rsquo;s subject key
identifier.  This is obtained by the X.509 Subject Key identifier
extension field (2.5.29.14).
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the extension is not present, otherwise a negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fsubject_005funique_005fid-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_subject_unique_id</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fsubject_005funique_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fsubject_005funique_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_subject_unique_id</strong> <em>(gnutls_x509_crt_t <var>crt</var>, char * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>buf</var>: user allocated memory buffer, will hold the unique id
</p>
<p><var>buf_size</var>: size of user allocated memory buffer (on input), will hold
actual size of the unique ID on return.
</p>
<p>This function will extract the subjectUniqueID value (if present) for
the given certificate.
</p>
<p>If the user allocated memory buffer is not large enough to hold the
full subjectUniqueID, then a GNUTLS_E_SHORT_MEMORY_BUFFER error will be
returned, and buf_size will be set to the actual length.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fversion-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_version</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fversion"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fversion"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_version</strong> <em>(gnutls_x509_crt_t <var>cert</var>)</em></dt>
<dd><p><var>cert</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p>This function will return the version of the specified Certificate.
</p>
<p><strong>Returns:</strong> version of certificate, or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fimport-1"></a>
<h4 class="subheading">gnutls_x509_crt_import</h4>
<a name="gnutls_005fx509_005fcrt_005fimport"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fimport"></a>Function: <em>int</em> <strong>gnutls_x509_crt_import</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>cert</var>: The data to store the parsed certificate.
</p>
<p><var>data</var>: The DER or PEM encoded certificate.
</p>
<p><var>format</var>: One of DER or PEM
</p>
<p>This function will convert the given DER or PEM encoded Certificate
to the native gnutls_x509_crt_t format. The output will be stored
in  <code>cert</code> .
</p>
<p>If the Certificate is PEM encoded it should have a header of &quot;X509
CERTIFICATE&quot;, or &quot;CERTIFICATE&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fimport_005furl-1"></a>
<h4 class="subheading">gnutls_x509_crt_import_url</h4>
<a name="gnutls_005fx509_005fcrt_005fimport_005furl"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fimport_005furl"></a>Function: <em>int</em> <strong>gnutls_x509_crt_import_url</strong> <em>(gnutls_x509_crt_t <var>crt</var>, const char * <var>url</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crt</var>: A certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>url</var>: A PKCS 11 url
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_* flags
</p>
<p>This function will import a PKCS 11 certificate directly from a token
without involving the <code>gnutls_pkcs11_obj_t</code>  type. This function will
fail if the certificate stored is not of X.509 type.
</p>
<p>Despite its name this function will attempt to import any kind of 
URL to certificate. In previous versions of gnutls this function
was named gnutls_x509_crt_import_pkcs11_url, and the old name is
an alias to this one.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005finit-1"></a>
<h4 class="subheading">gnutls_x509_crt_init</h4>
<a name="gnutls_005fx509_005fcrt_005finit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005finit"></a>Function: <em>int</em> <strong>gnutls_x509_crt_init</strong> <em>(gnutls_x509_crt_t * <var>cert</var>)</em></dt>
<dd><p><var>cert</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize an X.509 certificate structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005flist_005fimport-1"></a>
<h4 class="subheading">gnutls_x509_crt_list_import</h4>
<a name="gnutls_005fx509_005fcrt_005flist_005fimport"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005flist_005fimport"></a>Function: <em>int</em> <strong>gnutls_x509_crt_list_import</strong> <em>(gnutls_x509_crt_t * <var>certs</var>, unsigned int * <var>cert_max</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>certs</var>: Indicates where the parsed list will be copied to. Must not be initialized.
</p>
<p><var>cert_max</var>: Initially must hold the maximum number of certs. It will be updated with the number of certs available.
</p>
<p><var>data</var>: The PEM encoded certificate.
</p>
<p><var>format</var>: One of DER or PEM.
</p>
<p><var>flags</var>: must be (0) or an OR&rsquo;d sequence of gnutls_certificate_import_flags.
</p>
<p>This function will convert the given PEM encoded certificate list
to the native gnutls_x509_crt_t format. The output will be stored
in  <code>certs</code> .  They will be automatically initialized.
</p>
<p>The flag <code>GNUTLS_X509_CRT_LIST_IMPORT_FAIL_IF_EXCEED</code>  will cause
import to fail if the certificates in the provided buffer are more
than the available structures. The <code>GNUTLS_X509_CRT_LIST_FAIL_IF_UNSORTED</code> 
flag will cause the function to fail if the provided list is not
sorted from subject to issuer.
</p>
<p>If the Certificate is PEM encoded it should have a header of &quot;X509
CERTIFICATE&quot;, or &quot;CERTIFICATE&quot;.
</p>
<p><strong>Returns:</strong> the number of certificates read or a negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005flist_005fimport2-1"></a>
<h4 class="subheading">gnutls_x509_crt_list_import2</h4>
<a name="gnutls_005fx509_005fcrt_005flist_005fimport2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005flist_005fimport2"></a>Function: <em>int</em> <strong>gnutls_x509_crt_list_import2</strong> <em>(gnutls_x509_crt_t ** <var>certs</var>, unsigned int * <var>size</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>certs</var>: Will hold the parsed certificate list.
</p>
<p><var>size</var>: It will contain the size of the list.
</p>
<p><var>data</var>: The PEM encoded certificate.
</p>
<p><var>format</var>: One of DER or PEM.
</p>
<p><var>flags</var>: must be (0) or an OR&rsquo;d sequence of gnutls_certificate_import_flags.
</p>
<p>This function will convert the given PEM encoded certificate list
to the native gnutls_x509_crt_t format. The output will be stored
in  <code>certs</code> which will allocated and initialized.
</p>
<p>If the Certificate is PEM encoded it should have a header of &quot;X509
CERTIFICATE&quot;, or &quot;CERTIFICATE&quot;.
</p>
<p>To deinitialize  <code>certs</code> , you need to deinitialize each crt structure
independently, and use <code>gnutls_free()</code>  at
</p>
<p><strong>Returns:</strong> the number of certificates read or a negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005flist_005fverify-1"></a>
<h4 class="subheading">gnutls_x509_crt_list_verify</h4>
<a name="gnutls_005fx509_005fcrt_005flist_005fverify"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005flist_005fverify"></a>Function: <em>int</em> <strong>gnutls_x509_crt_list_verify</strong> <em>(const gnutls_x509_crt_t * <var>cert_list</var>, int <var>cert_list_length</var>, const gnutls_x509_crt_t * <var>CA_list</var>, int <var>CA_list_length</var>, const gnutls_x509_crl_t * <var>CRL_list</var>, int <var>CRL_list_length</var>, unsigned int <var>flags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>cert_list</var>: is the certificate list to be verified
</p>
<p><var>cert_list_length</var>: holds the number of certificate in cert_list
</p>
<p><var>CA_list</var>: is the CA list which will be used in verification
</p>
<p><var>CA_list_length</var>: holds the number of CA certificate in CA_list
</p>
<p><var>CRL_list</var>: holds a list of CRLs.
</p>
<p><var>CRL_list_length</var>: the length of CRL list.
</p>
<p><var>flags</var>: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.
</p>
<p><var>verify</var>: will hold the certificate verification output.
</p>

<p>This function will try to verify the given certificate list and
return its status. The details of the verification are the same
as in <code>gnutls_x509_trust_list_verify_crt2()</code> .
</p>
<p>You must check the peer&rsquo;s name in order to check if the verified
certificate belongs to the actual peer.
</p>
<p>The certificate verification output will be put in  <code>verify</code> and will
be one or more of the gnutls_certificate_status_t enumerated
elements bitwise or&rsquo;d.  For a more detailed verification status use
<code>gnutls_x509_crt_verify()</code>  per list element.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fprint-1"></a>
<h4 class="subheading">gnutls_x509_crt_print</h4>
<a name="gnutls_005fx509_005fcrt_005fprint"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fprint"></a>Function: <em>int</em> <strong>gnutls_x509_crt_print</strong> <em>(gnutls_x509_crt_t <var>cert</var>, gnutls_certificate_print_formats_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>cert</var>: The data to be printed
</p>
<p><var>format</var>: Indicate the format to use
</p>
<p><var>out</var>: Newly allocated datum with null terminated string.
</p>
<p>This function will pretty print a X.509 certificate, suitable for
display to a human.
</p>
<p>If the format is <code>GNUTLS_CRT_PRINT_FULL</code>  then all fields of the
certificate will be output, on multiple lines.  The
<code>GNUTLS_CRT_PRINT_ONELINE</code>  format will generate one line with some
selected fields, which is useful for logging purposes.
</p>
<p>The output  <code>out</code> needs to be deallocated using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005factivation_005ftime-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_activation_time</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005factivation_005ftime"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005factivation_005ftime"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_activation_time</strong> <em>(gnutls_x509_crt_t <var>cert</var>, time_t <var>act_time</var>)</em></dt>
<dd><p><var>cert</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>act_time</var>: The actual time
</p>
<p>This function will set the time this Certificate was or will be
activated.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fauthority_005finfo_005faccess-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_authority_info_access</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fauthority_005finfo_005faccess"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fauthority_005finfo_005faccess"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_authority_info_access</strong> <em>(gnutls_x509_crt_t <var>crt</var>, int <var>what</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>what</var>: what data to get, a <code>gnutls_info_access_what_t</code>  type.
</p>
<p><var>data</var>: output data to be freed with <code>gnutls_free()</code> .
</p>
<p>This function sets the Authority Information Access (AIA)
extension, see RFC 5280 section 4.2.2.1 for more information.  
</p>
<p>The type of data stored in  <code>data</code> is specified via  <code>what</code> which
should be <code>gnutls_info_access_what_t</code>  values.
</p>
<p>If  <code>what</code> is <code>GNUTLS_IA_OCSP_URI</code> ,  <code>data</code> will hold the OCSP URI.
If  <code>what</code> is <code>GNUTLS_IA_CAISSUERS_URI</code> ,  <code>data</code> will hold the caIssuers
URI.  
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fauthority_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_authority_key_id</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fauthority_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fauthority_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_authority_key_id</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const void * <var>id</var>, size_t <var>id_size</var>)</em></dt>
<dd><p><var>cert</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>id</var>: The key ID
</p>
<p><var>id_size</var>: Holds the size of the key ID field.
</p>
<p>This function will set the X.509 certificate&rsquo;s authority key ID extension.
Only the keyIdentifier field can be set with this function.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fbasic_005fconstraints-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_basic_constraints</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fbasic_005fconstraints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fbasic_005fconstraints"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_basic_constraints</strong> <em>(gnutls_x509_crt_t <var>crt</var>, unsigned int <var>ca</var>, int <var>pathLenConstraint</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>ca</var>: true(1) or false(0). Depending on the Certificate authority status.
</p>
<p><var>pathLenConstraint</var>: non-negative error codes indicate maximum length of path,
and negative error codes indicate that the pathLenConstraints field should
not be present.
</p>
<p>This function will set the basicConstraints certificate extension.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fca_005fstatus-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_ca_status</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fca_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fca_005fstatus"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_ca_status</strong> <em>(gnutls_x509_crt_t <var>crt</var>, unsigned int <var>ca</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>ca</var>: true(1) or false(0). Depending on the Certificate authority status.
</p>
<p>This function will set the basicConstraints certificate extension.
Use <code>gnutls_x509_crt_set_basic_constraints()</code>  if you want to control
the pathLenConstraint field too.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fcrl_005fdist_005fpoints-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_crl_dist_points</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fcrl_005fdist_005fpoints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fcrl_005fdist_005fpoints"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_crl_dist_points</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_subject_alt_name_t <var>type</var>, const void * <var>data_string</var>, unsigned int <var>reason_flags</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>type</var>: is one of the gnutls_x509_subject_alt_name_t enumerations
</p>
<p><var>data_string</var>: The data to be set
</p>
<p><var>reason_flags</var>: revocation reasons
</p>
<p>This function will set the CRL distribution points certificate extension.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fcrl_005fdist_005fpoints2-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_crl_dist_points2</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fcrl_005fdist_005fpoints2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fcrl_005fdist_005fpoints2"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_crl_dist_points2</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_subject_alt_name_t <var>type</var>, const void * <var>data</var>, unsigned int <var>data_size</var>, unsigned int <var>reason_flags</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>type</var>: is one of the gnutls_x509_subject_alt_name_t enumerations
</p>
<p><var>data</var>: The data to be set
</p>
<p><var>data_size</var>: The data size
</p>
<p><var>reason_flags</var>: revocation reasons
</p>
<p>This function will set the CRL distribution points certificate extension.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.6.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fcrq-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_crq</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fcrq"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fcrq"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_crq</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_crq_t <var>crq</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>crq</var>: holds a certificate request
</p>
<p>This function will set the name and public parameters as well as
the extensions from the given certificate request to the certificate. 
Only RSA keys are currently supported.
</p>
<p>Note that this function will only set the  <code>crq</code> if it is self
signed and the signature is correct. See <code>gnutls_x509_crq_sign2()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fcrq_005fextensions-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_crq_extensions</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fcrq_005fextensions"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fcrq_005fextensions"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_crq_extensions</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_crq_t <var>crq</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>crq</var>: holds a certificate request
</p>
<p>This function will set extensions from the given request to the
certificate.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.8.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fdn-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_dn</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fdn"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fdn"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_dn</strong> <em>(gnutls_x509_crt_t <var>crt</var>, const char * <var>dn</var>, const char ** <var>err</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>dn</var>: a comma separated DN string (RFC4514)
</p>
<p><var>err</var>: indicates the error position (if any)
</p>
<p>This function will set the DN on the provided certificate.
The input string should be plain ASCII or UTF-8 encoded.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fdn_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_dn_by_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fdn_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fdn_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_dn_by_oid</strong> <em>(gnutls_x509_crt_t <var>crt</var>, const char * <var>oid</var>, unsigned int <var>raw_flag</var>, const void * <var>name</var>, unsigned int <var>sizeof_name</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>oid</var>: holds an Object Identifier in a null terminated string
</p>
<p><var>raw_flag</var>: must be 0, or 1 if the data are DER encoded
</p>
<p><var>name</var>: a pointer to the name
</p>
<p><var>sizeof_name</var>: holds the size of  <code>name</code> 
</p>
<p>This function will set the part of the name of the Certificate
subject, specified by the given OID. The input string should be
ASCII or UTF-8 encoded.
</p>
<p>Some helper macros with popular OIDs can be found in gnutls/x509.h
With this function you can only set the known OIDs. You can test
for known OIDs using <code>gnutls_x509_dn_oid_known()</code> . For OIDs that are
not known (by gnutls) you should properly DER encode your data,
and call this function with  <code>raw_flag</code> set.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fexpiration_005ftime-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_expiration_time</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fexpiration_005ftime"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fexpiration_005ftime"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_expiration_time</strong> <em>(gnutls_x509_crt_t <var>cert</var>, time_t <var>exp_time</var>)</em></dt>
<dd><p><var>cert</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>exp_time</var>: The actual time
</p>
<p>This function will set the time this Certificate will expire.
Setting an expiration time to (time_t)-1 or to <code>GNUTLS_X509_NO_WELL_DEFINED_EXPIRATION</code> 
will set to the no well-defined expiration date value. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fextension_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_extension_by_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fextension_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fextension_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_extension_by_oid</strong> <em>(gnutls_x509_crt_t <var>crt</var>, const char * <var>oid</var>, const void * <var>buf</var>, size_t <var>sizeof_buf</var>, unsigned int <var>critical</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>oid</var>: holds an Object Identified in null terminated string
</p>
<p><var>buf</var>: a pointer to a DER encoded data
</p>
<p><var>sizeof_buf</var>: holds the size of  <code>buf</code> 
</p>
<p><var>critical</var>: should be non-zero if the extension is to be marked as critical
</p>
<p>This function will set an the extension, by the specified OID, in
the certificate.  The extension data should be binary data DER
encoded.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fissuer_005falt_005fname-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_issuer_alt_name</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fissuer_005falt_005fname"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fissuer_005falt_005fname"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_issuer_alt_name</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_subject_alt_name_t <var>type</var>, const void * <var>data</var>, unsigned int <var>data_size</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>type</var>: is one of the gnutls_x509_subject_alt_name_t enumerations
</p>
<p><var>data</var>: The data to be set
</p>
<p><var>data_size</var>: The size of data to be set
</p>
<p><var>flags</var>: GNUTLS_FSAN_SET to clear previous data or GNUTLS_FSAN_APPEND to append. 
</p>
<p>This function will set the issuer alternative name certificate
extension. It can set the same types as <code>gnutls_x509_crt_set_subject_alt_name()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fissuer_005fdn-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_issuer_dn</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fissuer_005fdn"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fissuer_005fdn"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_issuer_dn</strong> <em>(gnutls_x509_crt_t <var>crt</var>, const char * <var>dn</var>, const char ** <var>err</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>dn</var>: a comma separated DN string (RFC4514)
</p>
<p><var>err</var>: indicates the error position (if any)
</p>
<p>This function will set the DN on the provided certificate.
The input string should be plain ASCII or UTF-8 encoded.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fissuer_005fdn_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_issuer_dn_by_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fissuer_005fdn_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fissuer_005fdn_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_issuer_dn_by_oid</strong> <em>(gnutls_x509_crt_t <var>crt</var>, const char * <var>oid</var>, unsigned int <var>raw_flag</var>, const void * <var>name</var>, unsigned int <var>sizeof_name</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>oid</var>: holds an Object Identifier in a null terminated string
</p>
<p><var>raw_flag</var>: must be 0, or 1 if the data are DER encoded
</p>
<p><var>name</var>: a pointer to the name
</p>
<p><var>sizeof_name</var>: holds the size of  <code>name</code> 
</p>
<p>This function will set the part of the name of the Certificate
issuer, specified by the given OID.  The input string should be
ASCII or UTF-8 encoded.
</p>
<p>Some helper macros with popular OIDs can be found in gnutls/x509.h
With this function you can only set the known OIDs. You can test
for known OIDs using <code>gnutls_x509_dn_oid_known()</code> . For OIDs that are
not known (by gnutls) you should properly DER encode your data,
and call this function with  <code>raw_flag</code> set.
</p>
<p>Normally you do not need to call this function, since the signing
operation will copy the signer&rsquo;s name as the issuer of the
certificate.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fissuer_005funique_005fid-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_issuer_unique_id</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fissuer_005funique_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fissuer_005funique_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_issuer_unique_id</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const void * <var>id</var>, size_t <var>id_size</var>)</em></dt>
<dd><p><var>cert</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>id</var>: The unique ID
</p>
<p><var>id_size</var>: Holds the size of the unique ID.
</p>
<p>This function will set the X.509 certificate&rsquo;s issuer unique ID field.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.7
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fkey-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_key</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fkey"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fkey"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_key</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_privkey_t <var>key</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>key</var>: holds a private key
</p>
<p>This function will set the public parameters from the given
private key to the certificate. Only RSA keys are currently
supported.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fkey_005fpurpose_005foid-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_key_purpose_oid</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fkey_005fpurpose_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fkey_005fpurpose_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_key_purpose_oid</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const void * <var>oid</var>, unsigned int <var>critical</var>)</em></dt>
<dd><p><var>cert</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>oid</var>: a pointer to a null terminated string that holds the OID
</p>
<p><var>critical</var>: Whether this extension will be critical or not
</p>
<p>This function will set the key purpose OIDs of the Certificate.
These are stored in the Extended Key Usage extension (2.5.29.37)
See the GNUTLS_KP_* definitions for human readable names.
</p>
<p>Subsequent calls to this function will append OIDs to the OID list.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fkey_005fusage-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_key_usage</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fkey_005fusage"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fkey_005fusage"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_key_usage</strong> <em>(gnutls_x509_crt_t <var>crt</var>, unsigned int <var>usage</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>usage</var>: an ORed sequence of the GNUTLS_KEY_* elements.
</p>
<p>This function will set the keyUsage certificate extension.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fname_005fconstraints-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_name_constraints</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fname_005fconstraints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fname_005fconstraints"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_name_constraints</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_name_constraints_t <var>nc</var>, unsigned int <var>critical</var>)</em></dt>
<dd><p><var>crt</var>: The certificate
</p>
<p><var>nc</var>: The nameconstraints structure
</p>
<p><var>critical</var>: whether this extension will be critical
</p>
<p>This function will set the provided name constraints to
the certificate extension list. This extension is always
marked as critical.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fpin_005ffunction-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_pin_function</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fpin_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fpin_005ffunction"></a>Function: <em>void</em> <strong>gnutls_x509_crt_set_pin_function</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</em></dt>
<dd><p><var>crt</var>: The certificate structure
</p>
<p><var>fn</var>: the callback
</p>
<p><var>userdata</var>: data associated with the callback
</p>
<p>This function will set a callback function to be used when
it is required to access a protected object. This function overrides 
the global function set using <code>gnutls_pkcs11_set_pin_function()</code> .
</p>
<p>Note that this callback is currently used only during the import
of a PKCS <code>11</code>  certificate with <code>gnutls_x509_crt_import_url()</code> .
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fpolicy-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_policy</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fpolicy"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fpolicy"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_policy</strong> <em>(gnutls_x509_crt_t <var>crt</var>, const struct gnutls_x509_policy_st * <var>policy</var>, unsigned int <var>critical</var>)</em></dt>
<dd><p><var>crt</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>policy</var>: A pointer to a policy
</p>
<p><var>critical</var>: use non-zero if the extension is marked as critical
</p>
<p>This function will set the certificate policy extension (2.5.29.32).
Multiple calls to this function append a new policy.
</p>
<p>Note the maximum text size for the qualifier <code>GNUTLS_X509_QUALIFIER_NOTICE</code> 
is 200 characters. This function will fail with <code>GNUTLS_E_INVALID_REQUEST</code> 
if this is exceeded.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.5
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fprivate_005fkey_005fusage_005fperiod-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_private_key_usage_period</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fprivate_005fkey_005fusage_005fperiod"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fprivate_005fkey_005fusage_005fperiod"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_private_key_usage_period</strong> <em>(gnutls_x509_crt_t <var>crt</var>, time_t <var>activation</var>, time_t <var>expiration</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>activation</var>: The activation time
</p>
<p><var>expiration</var>: The expiration time
</p>
<p>This function will set the private key usage period extension (2.5.29.16).
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fproxy-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_proxy</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fproxy"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fproxy"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_proxy</strong> <em>(gnutls_x509_crt_t <var>crt</var>, int <var>pathLenConstraint</var>, const char * <var>policyLanguage</var>, const char * <var>policy</var>, size_t <var>sizeof_policy</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>pathLenConstraint</var>: non-negative error codes indicate maximum length of path,
and negative error codes indicate that the pathLenConstraints field should
not be present.
</p>
<p><var>policyLanguage</var>: OID describing the language of  <code>policy</code> .
</p>
<p><var>policy</var>: uint8_t byte array with policy language, can be <code>NULL</code> 
</p>
<p><var>sizeof_policy</var>: size of  <code>policy</code> .
</p>
<p>This function will set the proxyCertInfo extension.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fproxy_005fdn-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_proxy_dn</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fproxy_005fdn"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fproxy_005fdn"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_proxy_dn</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_crt_t <var>eecrt</var>, unsigned int <var>raw_flag</var>, const void * <var>name</var>, unsigned int <var>sizeof_name</var>)</em></dt>
<dd><p><var>crt</var>: a gnutls_x509_crt_t type with the new proxy cert
</p>
<p><var>eecrt</var>: the end entity certificate that will be issuing the proxy
</p>
<p><var>raw_flag</var>: must be 0, or 1 if the CN is DER encoded
</p>
<p><var>name</var>: a pointer to the CN name, may be NULL (but MUST then be added later)
</p>
<p><var>sizeof_name</var>: holds the size of  <code>name</code> 
</p>
<p>This function will set the subject in  <code>crt</code> to the end entity&rsquo;s
 <code>eecrt</code> subject name, and add a single Common Name component  <code>name</code> of size  <code>sizeof_name</code> .  This corresponds to the required proxy
certificate naming style.  Note that if  <code>name</code> is <code>NULL</code> , you MUST
set it later by using <code>gnutls_x509_crt_set_dn_by_oid()</code>  or similar.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fserial-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_serial</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fserial"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fserial"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_serial</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const void * <var>serial</var>, size_t <var>serial_size</var>)</em></dt>
<dd><p><var>cert</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>serial</var>: The serial number
</p>
<p><var>serial_size</var>: Holds the size of the serial field.
</p>
<p>This function will set the X.509 certificate&rsquo;s serial number.
While the serial number is an integer, it is often handled
as an opaque field by several CAs. For this reason this function
accepts any kind of data as a serial number. To be consistent
with the X.509/PKIX specifications the provided  <code>serial</code> should be 
a big-endian positive number (i.e. it&rsquo;s leftmost bit should be zero).
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fsubject_005falt_005fname-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_subject_alt_name</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fsubject_005falt_005fname"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fsubject_005falt_005fname"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_subject_alt_name</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_subject_alt_name_t <var>type</var>, const void * <var>data</var>, unsigned int <var>data_size</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>type</var>: is one of the gnutls_x509_subject_alt_name_t enumerations
</p>
<p><var>data</var>: The data to be set
</p>
<p><var>data_size</var>: The size of data to be set
</p>
<p><var>flags</var>: GNUTLS_FSAN_SET to clear previous data or GNUTLS_FSAN_APPEND to append. 
</p>
<p>This function will set the subject alternative name certificate
extension. It can set the following types:
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.6.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fsubject_005falternative_005fname-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_subject_alternative_name</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fsubject_005falternative_005fname"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fsubject_005falternative_005fname"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_subject_alternative_name</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_subject_alt_name_t           <var>type</var>, const char * <var>data_string</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>type</var>: is one of the gnutls_x509_subject_alt_name_t enumerations
</p>
<p><var>data_string</var>: The data to be set, a (0) terminated string
</p>
<p>This function will set the subject alternative name certificate
extension. This function assumes that data can be expressed as a null
terminated string.
</p>
<p>The name of the function is unfortunate since it is incosistent with
<code>gnutls_x509_crt_get_subject_alt_name()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fsubject_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_subject_key_id</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fsubject_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fsubject_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_subject_key_id</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const void * <var>id</var>, size_t <var>id_size</var>)</em></dt>
<dd><p><var>cert</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>id</var>: The key ID
</p>
<p><var>id_size</var>: Holds the size of the subject key ID field.
</p>
<p>This function will set the X.509 certificate&rsquo;s subject key ID
extension.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fsubject_005funique_005fid-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_subject_unique_id</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fsubject_005funique_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fsubject_005funique_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_subject_unique_id</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const void * <var>id</var>, size_t <var>id_size</var>)</em></dt>
<dd><p><var>cert</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>id</var>: The unique ID
</p>
<p><var>id_size</var>: Holds the size of the unique ID.
</p>
<p>This function will set the X.509 certificate&rsquo;s subject unique ID field.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.7
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fversion-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_version</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fversion"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fversion"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_version</strong> <em>(gnutls_x509_crt_t <var>crt</var>, unsigned int <var>version</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>version</var>: holds the version number. For X.509v1 certificates must be 1.
</p>
<p>This function will set the version of the certificate.  This must
be one for X.509 version 1, and so on.  Plain certificates without
extensions must have version set to one.
</p>
<p>To create well-formed certificates, you must specify version 3 if
you use any certificate extensions.  Extensions are created by
functions such as <code>gnutls_x509_crt_set_subject_alt_name()</code> 
or <code>gnutls_x509_crt_set_key_usage()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fsign-1"></a>
<h4 class="subheading">gnutls_x509_crt_sign</h4>
<a name="gnutls_005fx509_005fcrt_005fsign"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fsign"></a>Function: <em>int</em> <strong>gnutls_x509_crt_sign</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_crt_t <var>issuer</var>, gnutls_x509_privkey_t <var>issuer_key</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>issuer</var>: is the certificate of the certificate issuer
</p>
<p><var>issuer_key</var>: holds the issuer&rsquo;s private key
</p>
<p>This function is the same a <code>gnutls_x509_crt_sign2()</code>  with no flags,
and SHA1 as the hash algorithm.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fsign2-1"></a>
<h4 class="subheading">gnutls_x509_crt_sign2</h4>
<a name="gnutls_005fx509_005fcrt_005fsign2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fsign2"></a>Function: <em>int</em> <strong>gnutls_x509_crt_sign2</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_crt_t <var>issuer</var>, gnutls_x509_privkey_t <var>issuer_key</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>issuer</var>: is the certificate of the certificate issuer
</p>
<p><var>issuer_key</var>: holds the issuer&rsquo;s private key
</p>
<p><var>dig</var>: The message digest to use, <code>GNUTLS_DIG_SHA1</code>  is a safe choice
</p>
<p><var>flags</var>: must be 0
</p>
<p>This function will sign the certificate with the issuer&rsquo;s private key, and
will copy the issuer&rsquo;s information into the certificate.
</p>
<p>This must be the last step in a certificate generation since all
the previously set parameters are now signed.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fverify-1"></a>
<h4 class="subheading">gnutls_x509_crt_verify</h4>
<a name="gnutls_005fx509_005fcrt_005fverify"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fverify"></a>Function: <em>int</em> <strong>gnutls_x509_crt_verify</strong> <em>(gnutls_x509_crt_t <var>cert</var>, const gnutls_x509_crt_t * <var>CA_list</var>, int <var>CA_list_length</var>, unsigned int <var>flags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>cert</var>: is the certificate to be verified
</p>
<p><var>CA_list</var>: is one certificate that is considered to be trusted one
</p>
<p><var>CA_list_length</var>: holds the number of CA certificate in CA_list
</p>
<p><var>flags</var>: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.
</p>
<p><var>verify</var>: will hold the certificate verification output.
</p>
<p>This function will try to verify the given certificate and return
its status. Note that a verification error does not imply a negative
return status. In that case the  <code>verify</code> status is set.
</p>
<p>The details of the verification are the same
as in <code>gnutls_x509_trust_list_verify_crt2()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fverify_005fdata2-1"></a>
<h4 class="subheading">gnutls_x509_crt_verify_data2</h4>
<a name="gnutls_005fx509_005fcrt_005fverify_005fdata2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fverify_005fdata2"></a>Function: <em>int</em> <strong>gnutls_x509_crt_verify_data2</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_sign_algorithm_t <var>algo</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>data</var>, const gnutls_datum_t * <var>signature</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate to verify with
</p>
<p><var>algo</var>: The signature algorithm used
</p>
<p><var>flags</var>: Zero or an OR list of <code>gnutls_certificate_verify_flags</code> 
</p>
<p><var>data</var>: holds the signed data
</p>
<p><var>signature</var>: contains the signature
</p>
<p>This function will verify the given signed data, using the
parameters from the certificate.
</p>
<p><strong>Returns:</strong> In case of a verification failure <code>GNUTLS_E_PK_SIG_VERIFY_FAILED</code>  
is returned, and zero or positive code on success.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fx509_005fdn_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_dn_deinit</h4>
<a name="gnutls_005fx509_005fdn_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fdn_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_dn_deinit</strong> <em>(gnutls_x509_dn_t <var>dn</var>)</em></dt>
<dd><p><var>dn</var>: a DN uint8_t object pointer.
</p>
<p>This function deallocates the DN object as returned by
<code>gnutls_x509_dn_import()</code> .
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fx509_005fdn_005fexport-1"></a>
<h4 class="subheading">gnutls_x509_dn_export</h4>
<a name="gnutls_005fx509_005fdn_005fexport"></a><dl>
<dt><a name="index-gnutls_005fx509_005fdn_005fexport"></a>Function: <em>int</em> <strong>gnutls_x509_dn_export</strong> <em>(gnutls_x509_dn_t <var>dn</var>, gnutls_x509_crt_fmt_t <var>format</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>dn</var>: Holds the uint8_t DN object
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>output_data</var>: will contain a DN PEM or DER encoded
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will export the DN to DER or PEM format.
</p>
<p>If the buffer provided is not long enough to hold the output, then
* <code>output_data_size</code> is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code> 
will be returned.
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN NAME&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fdn_005fexport2-1"></a>
<h4 class="subheading">gnutls_x509_dn_export2</h4>
<a name="gnutls_005fx509_005fdn_005fexport2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fdn_005fexport2"></a>Function: <em>int</em> <strong>gnutls_x509_dn_export2</strong> <em>(gnutls_x509_dn_t <var>dn</var>, gnutls_x509_crt_fmt_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>dn</var>: Holds the uint8_t DN object
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>out</var>: will contain a DN PEM or DER encoded
</p>
<p>This function will export the DN to DER or PEM format.
</p>
<p>The output buffer is allocated using <code>gnutls_malloc()</code> .
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN NAME&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fx509_005fdn_005fget_005frdn_005fava-1"></a>
<h4 class="subheading">gnutls_x509_dn_get_rdn_ava</h4>
<a name="gnutls_005fx509_005fdn_005fget_005frdn_005fava"></a><dl>
<dt><a name="index-gnutls_005fx509_005fdn_005fget_005frdn_005fava-1"></a>Function: <em>int</em> <strong>gnutls_x509_dn_get_rdn_ava</strong> <em>(gnutls_x509_dn_t <var>dn</var>, int <var>irdn</var>, int <var>iava</var>, gnutls_x509_ava_st * <var>ava</var>)</em></dt>
<dd><p><var>dn</var>: a pointer to DN
</p>
<p><var>irdn</var>: index of RDN
</p>
<p><var>iava</var>: index of AVA.
</p>
<p><var>ava</var>: Pointer to structure which will hold output information.
</p>
<p>Get pointers to data within the DN. The format of the  <code>ava</code> structure
is shown below.
</p>
<p>struct gnutls_x509_ava_st {
gnutls_datum_t oid;
gnutls_datum_t value;
unsigned long value_tag;
};
</p>
<p>The X.509 distinguished name is a sequence of sequences of strings
and this is what the  <code>irdn</code> and  <code>iava</code> indexes model.
</p>
<p>Note that  <code>ava</code> will contain pointers into the  <code>dn</code> structure which
in turns points to the original certificate. Thus you should not
modify any data or deallocate any of those.
</p>
<p>This is a low-level function that requires the caller to do the
value conversions when necessary (e.g. from UCS-2).
</p>
<p><strong>Returns:</strong> Returns 0 on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fx509_005fdn_005fget_005fstr-1"></a>
<h4 class="subheading">gnutls_x509_dn_get_str</h4>
<a name="gnutls_005fx509_005fdn_005fget_005fstr"></a><dl>
<dt><a name="index-gnutls_005fx509_005fdn_005fget_005fstr"></a>Function: <em>int</em> <strong>gnutls_x509_dn_get_str</strong> <em>(gnutls_x509_dn_t <var>dn</var>, gnutls_datum_t * <var>str</var>)</em></dt>
<dd><p><var>dn</var>: a pointer to DN
</p>
<p><var>str</var>: a datum that will hold the name
</p>
<p>This function will allocate buffer and copy the name in the provided DN.
The name will be in the form &quot;C=xxxx,O=yyyy,CN=zzzz&quot; as
described in RFC4514. The output string will be ASCII or UTF-8
encoded, depending on the certificate data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<a name="gnutls_005fx509_005fdn_005fimport-1"></a>
<h4 class="subheading">gnutls_x509_dn_import</h4>
<a name="gnutls_005fx509_005fdn_005fimport"></a><dl>
<dt><a name="index-gnutls_005fx509_005fdn_005fimport"></a>Function: <em>int</em> <strong>gnutls_x509_dn_import</strong> <em>(gnutls_x509_dn_t <var>dn</var>, const gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>dn</var>: the structure that will hold the imported DN
</p>
<p><var>data</var>: should contain a DER encoded RDN sequence
</p>
<p>This function parses an RDN sequence and stores the result to a
<code>gnutls_x509_dn_t</code>  type. The data must have been initialized
with <code>gnutls_x509_dn_init()</code> . You may use <code>gnutls_x509_dn_get_rdn_ava()</code>  to
decode the DN.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fx509_005fdn_005finit-1"></a>
<h4 class="subheading">gnutls_x509_dn_init</h4>
<a name="gnutls_005fx509_005fdn_005finit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fdn_005finit"></a>Function: <em>int</em> <strong>gnutls_x509_dn_init</strong> <em>(gnutls_x509_dn_t * <var>dn</var>)</em></dt>
<dd><p><var>dn</var>: the object to be initialized
</p>
<p>This function initializes a <code>gnutls_x509_dn_t</code>  type.
</p>
<p>The object returned must be deallocated using
<code>gnutls_x509_dn_deinit()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fx509_005fdn_005foid_005fknown-1"></a>
<h4 class="subheading">gnutls_x509_dn_oid_known</h4>
<a name="gnutls_005fx509_005fdn_005foid_005fknown"></a><dl>
<dt><a name="index-gnutls_005fx509_005fdn_005foid_005fknown"></a>Function: <em>int</em> <strong>gnutls_x509_dn_oid_known</strong> <em>(const char * <var>oid</var>)</em></dt>
<dd><p><var>oid</var>: holds an Object Identifier in a null terminated string
</p>
<p>This function will inform about known DN OIDs. This is useful since
functions like <code>gnutls_x509_crt_set_dn_by_oid()</code>  use the information
on known OIDs to properly encode their input. Object Identifiers
that are not known are not encoded by these functions, and their
input is stored directly into the ASN.1 structure. In that case of
unknown OIDs, you have the responsibility of DER encoding your
data.
</p>
<p><strong>Returns:</strong> 1 on known OIDs and 0 otherwise.
</p></dd></dl>

<a name="gnutls_005fx509_005fdn_005foid_005fname-1"></a>
<h4 class="subheading">gnutls_x509_dn_oid_name</h4>
<a name="gnutls_005fx509_005fdn_005foid_005fname"></a><dl>
<dt><a name="index-gnutls_005fx509_005fdn_005foid_005fname"></a>Function: <em>const char *</em> <strong>gnutls_x509_dn_oid_name</strong> <em>(const char * <var>oid</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>oid</var>: holds an Object Identifier in a null terminated string
</p>
<p><var>flags</var>: 0 or GNUTLS_X509_DN_OID_*
</p>
<p>This function will return the name of a known DN OID. If
<code>GNUTLS_X509_DN_OID_RETURN_OID</code>  is specified this function
will return the given OID if no descriptive name has been
found.
</p>
<p><strong>Returns:</strong> A null terminated string or NULL otherwise.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_ext_deinit</h4>
<a name="gnutls_005fx509_005fext_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_ext_deinit</strong> <em>(gnutls_x509_ext_st * <var>ext</var>)</em></dt>
<dd><p><var>ext</var>: The extensions structure
</p>
<p>This function will deinitialize an extensions structure.
</p>
<p><strong>Since:</strong> 3.3.8
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fexport_005faia-1"></a>
<h4 class="subheading">gnutls_x509_ext_export_aia</h4>
<a name="gnutls_005fx509_005fext_005fexport_005faia"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fexport_005faia"></a>Function: <em>int</em> <strong>gnutls_x509_ext_export_aia</strong> <em>(gnutls_x509_aia_t <var>aia</var>, gnutls_datum_t * <var>ext</var>)</em></dt>
<dd><p><var>aia</var>: The authority info access
</p>
<p><var>ext</var>: The DER-encoded extension data; must be freed using <code>gnutls_free()</code> .
</p>
<p>This function will DER encode the Authority Information Access (AIA)
extension; see RFC 5280 section 4.2.2.1 for more information on the
extension.  
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fexport_005fauthority_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_ext_export_authority_key_id</h4>
<a name="gnutls_005fx509_005fext_005fexport_005fauthority_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fexport_005fauthority_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_ext_export_authority_key_id</strong> <em>(gnutls_x509_aki_t <var>aki</var>, gnutls_datum_t * <var>ext</var>)</em></dt>
<dd><p><var>aki</var>: An initialized authority key identifier
</p>
<p><var>ext</var>: The DER-encoded extension data; must be freed using <code>gnutls_free()</code> .
</p>
<p>This function will convert the provided key identifier to a
DER-encoded PKIX AuthorityKeyIdentifier extension. 
The output data in  <code>ext</code> will be allocated using
<code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fexport_005fbasic_005fconstraints-1"></a>
<h4 class="subheading">gnutls_x509_ext_export_basic_constraints</h4>
<a name="gnutls_005fx509_005fext_005fexport_005fbasic_005fconstraints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fexport_005fbasic_005fconstraints"></a>Function: <em>int</em> <strong>gnutls_x509_ext_export_basic_constraints</strong> <em>(unsigned int <var>ca</var>, int <var>pathlen</var>, gnutls_datum_t * <var>ext</var>)</em></dt>
<dd><p><var>ca</var>: non-zero for a CA
</p>
<p><var>pathlen</var>: The path length constraint (set to -1 for no constraint)
</p>
<p><var>ext</var>: The DER-encoded extension data; must be freed using <code>gnutls_free()</code> .
</p>
<p>This function will convert the parameters provided to a basic constraints
DER encoded extension (2.5.29.19).
The  <code>ext</code> data will be allocated using
<code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fexport_005fcrl_005fdist_005fpoints-1"></a>
<h4 class="subheading">gnutls_x509_ext_export_crl_dist_points</h4>
<a name="gnutls_005fx509_005fext_005fexport_005fcrl_005fdist_005fpoints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fexport_005fcrl_005fdist_005fpoints"></a>Function: <em>int</em> <strong>gnutls_x509_ext_export_crl_dist_points</strong> <em>(gnutls_x509_crl_dist_points_t <var>cdp</var>, gnutls_datum_t * <var>ext</var>)</em></dt>
<dd><p><var>cdp</var>: A pointer to an initialized CRL distribution points.
</p>
<p><var>ext</var>: The DER-encoded extension data; must be freed using <code>gnutls_free()</code> .
</p>
<p>This function will convert the provided policies, to a certificate policy
DER encoded extension (2.5.29.31).
</p>
<p>The  <code>ext</code> data will be allocated using <code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fexport_005fkey_005fpurposes-1"></a>
<h4 class="subheading">gnutls_x509_ext_export_key_purposes</h4>
<a name="gnutls_005fx509_005fext_005fexport_005fkey_005fpurposes"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fexport_005fkey_005fpurposes"></a>Function: <em>int</em> <strong>gnutls_x509_ext_export_key_purposes</strong> <em>(gnutls_x509_key_purposes_t <var>p</var>, gnutls_datum_t * <var>ext</var>)</em></dt>
<dd><p><var>p</var>: The key purposes
</p>
<p><var>ext</var>: The DER-encoded extension data; must be freed using <code>gnutls_free()</code> .
</p>
<p>This function will convert the key purposes type to a
DER-encoded PKIX ExtKeyUsageSyntax (2.5.29.37) extension. The output data in 
 <code>ext</code> will be allocated usin <code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fexport_005fkey_005fusage-1"></a>
<h4 class="subheading">gnutls_x509_ext_export_key_usage</h4>
<a name="gnutls_005fx509_005fext_005fexport_005fkey_005fusage"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fexport_005fkey_005fusage"></a>Function: <em>int</em> <strong>gnutls_x509_ext_export_key_usage</strong> <em>(unsigned int <var>usage</var>, gnutls_datum_t * <var>ext</var>)</em></dt>
<dd><p><var>usage</var>: an ORed sequence of the GNUTLS_KEY_* elements.
</p>
<p><var>ext</var>: The DER-encoded extension data; must be freed using <code>gnutls_free()</code> .
</p>
<p>This function will convert the keyUsage bit string to a DER
encoded PKIX extension. The  <code>ext</code> data will be allocated using
<code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fexport_005fname_005fconstraints-1"></a>
<h4 class="subheading">gnutls_x509_ext_export_name_constraints</h4>
<a name="gnutls_005fx509_005fext_005fexport_005fname_005fconstraints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fexport_005fname_005fconstraints"></a>Function: <em>int</em> <strong>gnutls_x509_ext_export_name_constraints</strong> <em>(gnutls_x509_name_constraints_t <var>nc</var>, gnutls_datum_t * <var>ext</var>)</em></dt>
<dd><p><var>nc</var>: The nameconstraints
</p>
<p><var>ext</var>: The DER-encoded extension data; must be freed using <code>gnutls_free()</code> .
</p>
<p>This function will convert the provided name constraints type to a
DER-encoded PKIX NameConstraints (2.5.29.30) extension. The output data in 
 <code>ext</code> will be allocated usin <code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fexport_005fpolicies-1"></a>
<h4 class="subheading">gnutls_x509_ext_export_policies</h4>
<a name="gnutls_005fx509_005fext_005fexport_005fpolicies"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fexport_005fpolicies"></a>Function: <em>int</em> <strong>gnutls_x509_ext_export_policies</strong> <em>(gnutls_x509_policies_t <var>policies</var>, gnutls_datum_t * <var>ext</var>)</em></dt>
<dd><p><var>policies</var>: A pointer to an initialized policies.
</p>
<p><var>ext</var>: The DER-encoded extension data; must be freed using <code>gnutls_free()</code> .
</p>
<p>This function will convert the provided policies, to a certificate policy
DER encoded extension (2.5.29.32).
</p>
<p>The  <code>ext</code> data will be allocated using <code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fexport_005fprivate_005fkey_005fusage_005fperiod-1"></a>
<h4 class="subheading">gnutls_x509_ext_export_private_key_usage_period</h4>
<a name="gnutls_005fx509_005fext_005fexport_005fprivate_005fkey_005fusage_005fperiod"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fexport_005fprivate_005fkey_005fusage_005fperiod"></a>Function: <em>int</em> <strong>gnutls_x509_ext_export_private_key_usage_period</strong> <em>(time_t <var>activation</var>, time_t <var>expiration</var>, gnutls_datum_t * <var>ext</var>)</em></dt>
<dd><p><var>activation</var>: The activation time
</p>
<p><var>expiration</var>: The expiration time
</p>
<p><var>ext</var>: The DER-encoded extension data; must be freed using <code>gnutls_free()</code> .
</p>
<p>This function will convert the periods provided to a private key
usage DER encoded extension (2.5.29.16).
The  <code>ext</code> data will be allocated using
<code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fexport_005fproxy-1"></a>
<h4 class="subheading">gnutls_x509_ext_export_proxy</h4>
<a name="gnutls_005fx509_005fext_005fexport_005fproxy"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fexport_005fproxy"></a>Function: <em>int</em> <strong>gnutls_x509_ext_export_proxy</strong> <em>(int <var>pathLenConstraint</var>, const char * <var>policyLanguage</var>, const char * <var>policy</var>, size_t <var>sizeof_policy</var>, gnutls_datum_t * <var>ext</var>)</em></dt>
<dd><p><var>pathLenConstraint</var>: non-negative error codes indicate maximum length of path,
and negative error codes indicate that the pathLenConstraints field should
not be present.
</p>
<p><var>policyLanguage</var>: OID describing the language of  <code>policy</code> .
</p>
<p><var>policy</var>: uint8_t byte array with policy language, can be <code>NULL</code> 
</p>
<p><var>sizeof_policy</var>: size of  <code>policy</code> .
</p>
<p><var>ext</var>: The DER-encoded extension data; must be freed using <code>gnutls_free()</code> .
</p>
<p>This function will convert the parameters provided to a proxyCertInfo extension.
</p>
<p>The  <code>ext</code> data will be allocated using
<code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fexport_005fsubject_005falt_005fnames-1"></a>
<h4 class="subheading">gnutls_x509_ext_export_subject_alt_names</h4>
<a name="gnutls_005fx509_005fext_005fexport_005fsubject_005falt_005fnames"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fexport_005fsubject_005falt_005fnames"></a>Function: <em>int</em> <strong>gnutls_x509_ext_export_subject_alt_names</strong> <em>(gnutls_subject_alt_names_t <var>sans</var>, gnutls_datum_t * <var>ext</var>)</em></dt>
<dd><p><var>sans</var>: The alternative names
</p>
<p><var>ext</var>: The DER-encoded extension data; must be freed using <code>gnutls_free()</code> .
</p>
<p>This function will convert the provided alternative names structure to a
DER-encoded SubjectAltName PKIX extension. The output data in  <code>ext</code> will be allocated using
<code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fexport_005fsubject_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_ext_export_subject_key_id</h4>
<a name="gnutls_005fx509_005fext_005fexport_005fsubject_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fexport_005fsubject_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_ext_export_subject_key_id</strong> <em>(const gnutls_datum_t * <var>id</var>, gnutls_datum_t * <var>ext</var>)</em></dt>
<dd><p><var>id</var>: The key identifier
</p>
<p><var>ext</var>: The DER-encoded extension data; must be freed using <code>gnutls_free()</code> .
</p>
<p>This function will convert the provided key identifier to a
DER-encoded PKIX SubjectKeyIdentifier extension. 
The output data in  <code>ext</code> will be allocated using
<code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fimport_005faia-1"></a>
<h4 class="subheading">gnutls_x509_ext_import_aia</h4>
<a name="gnutls_005fx509_005fext_005fimport_005faia"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fimport_005faia"></a>Function: <em>int</em> <strong>gnutls_x509_ext_import_aia</strong> <em>(const gnutls_datum_t * <var>ext</var>, gnutls_x509_aia_t <var>aia</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>ext</var>: The DER-encoded extension data
</p>
<p><var>aia</var>: The authority info access
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function extracts the Authority Information Access (AIA)
extension from the provided DER-encoded data; see RFC 5280 section 4.2.2.1 
for more information on the extension.  The
AIA extension holds a sequence of AccessDescription (AD) data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fimport_005fauthority_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_ext_import_authority_key_id</h4>
<a name="gnutls_005fx509_005fext_005fimport_005fauthority_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fimport_005fauthority_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_ext_import_authority_key_id</strong> <em>(const gnutls_datum_t * <var>ext</var>, gnutls_x509_aki_t <var>aki</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>ext</var>: a DER encoded extension
</p>
<p><var>aki</var>: An initialized authority key identifier type
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will return the subject key ID stored in the provided
AuthorityKeyIdentifier extension.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the extension is not present, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fimport_005fbasic_005fconstraints-1"></a>
<h4 class="subheading">gnutls_x509_ext_import_basic_constraints</h4>
<a name="gnutls_005fx509_005fext_005fimport_005fbasic_005fconstraints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fimport_005fbasic_005fconstraints"></a>Function: <em>int</em> <strong>gnutls_x509_ext_import_basic_constraints</strong> <em>(const gnutls_datum_t * <var>ext</var>, unsigned int * <var>ca</var>, int * <var>pathlen</var>)</em></dt>
<dd><p><var>ext</var>: the DER encoded extension data
</p>
<p><var>ca</var>: will be non zero if the CA status is true
</p>
<p><var>pathlen</var>: the path length constraint; will be set to -1 for no limit
</p>
<p>This function will return the CA status and path length constraint
as written in the PKIX extension 2.5.29.19.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fimport_005fcrl_005fdist_005fpoints-1"></a>
<h4 class="subheading">gnutls_x509_ext_import_crl_dist_points</h4>
<a name="gnutls_005fx509_005fext_005fimport_005fcrl_005fdist_005fpoints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fimport_005fcrl_005fdist_005fpoints"></a>Function: <em>int</em> <strong>gnutls_x509_ext_import_crl_dist_points</strong> <em>(const gnutls_datum_t * <var>ext</var>, gnutls_x509_crl_dist_points_t <var>cdp</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>ext</var>: the DER encoded extension data
</p>
<p><var>cdp</var>: A pointer to an initialized CRL distribution points.
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will extract the CRL distribution points extension (2.5.29.31) 
and store it into the provided type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fimport_005fkey_005fpurposes-1"></a>
<h4 class="subheading">gnutls_x509_ext_import_key_purposes</h4>
<a name="gnutls_005fx509_005fext_005fimport_005fkey_005fpurposes"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fimport_005fkey_005fpurposes"></a>Function: <em>int</em> <strong>gnutls_x509_ext_import_key_purposes</strong> <em>(const gnutls_datum_t * <var>ext</var>, gnutls_x509_key_purposes_t <var>p</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>ext</var>: The DER-encoded extension data
</p>
<p><var>p</var>: The key purposes
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will extract the key purposes in the provided DER-encoded
ExtKeyUsageSyntax PKIX extension, to a <code>gnutls_x509_key_purposes_t</code>  type. 
The data must be initialized.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fimport_005fkey_005fusage-1"></a>
<h4 class="subheading">gnutls_x509_ext_import_key_usage</h4>
<a name="gnutls_005fx509_005fext_005fimport_005fkey_005fusage"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fimport_005fkey_005fusage"></a>Function: <em>int</em> <strong>gnutls_x509_ext_import_key_usage</strong> <em>(const gnutls_datum_t * <var>ext</var>, unsigned int * <var>key_usage</var>)</em></dt>
<dd><p><var>ext</var>: the DER encoded extension data
</p>
<p><var>key_usage</var>: where the key usage bits will be stored
</p>
<p>This function will return certificate&rsquo;s key usage, by reading the DER
data of the keyUsage X.509 extension (2.5.29.15). The key usage value will ORed
values of the: <code>GNUTLS_KEY_DIGITAL_SIGNATURE</code> ,
<code>GNUTLS_KEY_NON_REPUDIATION</code> , <code>GNUTLS_KEY_KEY_ENCIPHERMENT</code> ,
<code>GNUTLS_KEY_DATA_ENCIPHERMENT</code> , <code>GNUTLS_KEY_KEY_AGREEMENT</code> ,
<code>GNUTLS_KEY_KEY_CERT_SIGN</code> , <code>GNUTLS_KEY_CRL_SIGN</code> ,
<code>GNUTLS_KEY_ENCIPHER_ONLY</code> , <code>GNUTLS_KEY_DECIPHER_ONLY</code> .
</p>
<p><strong>Returns:</strong> the certificate key usage, or a negative error code in case of
parsing error.  If the certificate does not contain the keyUsage
extension <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be
returned.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fimport_005fname_005fconstraints-1"></a>
<h4 class="subheading">gnutls_x509_ext_import_name_constraints</h4>
<a name="gnutls_005fx509_005fext_005fimport_005fname_005fconstraints"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fimport_005fname_005fconstraints"></a>Function: <em>int</em> <strong>gnutls_x509_ext_import_name_constraints</strong> <em>(const gnutls_datum_t * <var>ext</var>, gnutls_x509_name_constraints_t <var>nc</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>ext</var>: a DER encoded extension
</p>
<p><var>nc</var>: The nameconstraints
</p>
<p><var>flags</var>: zero or <code>GNUTLS_NAME_CONSTRAINTS_FLAG_APPEND</code> 
</p>
<p>This function will return an intermediate type containing
the name constraints of the provided NameConstraints extension. That
can be used in combination with <code>gnutls_x509_name_constraints_check()</code> 
to verify whether a server&rsquo;s name is in accordance with the constraints.
</p>
<p>When the  <code>flags</code> is set to <code>GNUTLS_NAME_CONSTRAINTS_FLAG_APPEND</code> , then if 
the  <code>nc</code> type is empty this function will behave identically as if the flag was not set.
Otherwise if there are elements in the  <code>nc</code> type then only the
excluded constraints will be appended to the constraints.
</p>
<p>Note that  <code>nc</code> must be initialized prior to calling this function.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the extension is not present, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fimport_005fpolicies-1"></a>
<h4 class="subheading">gnutls_x509_ext_import_policies</h4>
<a name="gnutls_005fx509_005fext_005fimport_005fpolicies"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fimport_005fpolicies"></a>Function: <em>int</em> <strong>gnutls_x509_ext_import_policies</strong> <em>(const gnutls_datum_t * <var>ext</var>, gnutls_x509_policies_t <var>policies</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>ext</var>: the DER encoded extension data
</p>
<p><var>policies</var>: A pointer to an initialized policies.
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will extract the certificate policy extension (2.5.29.32) 
and store it the provided policies.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fimport_005fprivate_005fkey_005fusage_005fperiod-1"></a>
<h4 class="subheading">gnutls_x509_ext_import_private_key_usage_period</h4>
<a name="gnutls_005fx509_005fext_005fimport_005fprivate_005fkey_005fusage_005fperiod"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fimport_005fprivate_005fkey_005fusage_005fperiod"></a>Function: <em>int</em> <strong>gnutls_x509_ext_import_private_key_usage_period</strong> <em>(const gnutls_datum_t * <var>ext</var>, time_t * <var>activation</var>, time_t * <var>expiration</var>)</em></dt>
<dd><p><var>ext</var>: the DER encoded extension data
</p>
<p><var>activation</var>: Will hold the activation time
</p>
<p><var>expiration</var>: Will hold the expiration time
</p>
<p>This function will return the expiration and activation
times of the private key as written in the
PKIX extension 2.5.29.16.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fimport_005fproxy-1"></a>
<h4 class="subheading">gnutls_x509_ext_import_proxy</h4>
<a name="gnutls_005fx509_005fext_005fimport_005fproxy"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fimport_005fproxy"></a>Function: <em>int</em> <strong>gnutls_x509_ext_import_proxy</strong> <em>(const gnutls_datum_t * <var>ext</var>, int * <var>pathlen</var>, char ** <var>policyLanguage</var>, char ** <var>policy</var>, size_t * <var>sizeof_policy</var>)</em></dt>
<dd><p><var>ext</var>: the DER encoded extension data
</p>
<p><var>pathlen</var>: pointer to output integer indicating path length (may be
NULL), non-negative error codes indicate a present pCPathLenConstraint
field and the actual value, -1 indicate that the field is absent.
</p>
<p><var>policyLanguage</var>: output variable with OID of policy language
</p>
<p><var>policy</var>: output variable with policy data
</p>
<p><var>sizeof_policy</var>: output variable size of policy data
</p>
<p>This function will return the information from a proxy certificate
extension. It reads the ProxyCertInfo X.509 extension (1.3.6.1.5.5.7.1.14).
The  <code>policyLanguage</code> and  <code>policy</code> values must be deinitialized using <code>gnutls_free()</code>  after use.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fimport_005fsubject_005falt_005fnames-1"></a>
<h4 class="subheading">gnutls_x509_ext_import_subject_alt_names</h4>
<a name="gnutls_005fx509_005fext_005fimport_005fsubject_005falt_005fnames"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fimport_005fsubject_005falt_005fnames"></a>Function: <em>int</em> <strong>gnutls_x509_ext_import_subject_alt_names</strong> <em>(const gnutls_datum_t * <var>ext</var>, gnutls_subject_alt_names_t <var>sans</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>ext</var>: The DER-encoded extension data
</p>
<p><var>sans</var>: The alternative names
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will export the alternative names in the provided DER-encoded
SubjectAltName PKIX extension, to a <code>gnutls_subject_alt_names_t</code>  type.  <code>sans</code> must be initialized.
</p>
<p>This function will succeed even if there no subject alternative names
in the structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fimport_005fsubject_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_ext_import_subject_key_id</h4>
<a name="gnutls_005fx509_005fext_005fimport_005fsubject_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fimport_005fsubject_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_ext_import_subject_key_id</strong> <em>(const gnutls_datum_t * <var>ext</var>, gnutls_datum_t * <var>id</var>)</em></dt>
<dd><p><var>ext</var>: a DER encoded extension
</p>
<p><var>id</var>: will contain the subject key ID
</p>
<p>This function will return the subject key ID stored in the provided
SubjectKeyIdentifier extension. The ID will be allocated using
<code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the extension is not present, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fext_005fprint-1"></a>
<h4 class="subheading">gnutls_x509_ext_print</h4>
<a name="gnutls_005fx509_005fext_005fprint"></a><dl>
<dt><a name="index-gnutls_005fx509_005fext_005fprint"></a>Function: <em>int</em> <strong>gnutls_x509_ext_print</strong> <em>(gnutls_x509_ext_st * <var>exts</var>, unsigned int <var>exts_size</var>, gnutls_certificate_print_formats_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>exts</var>: The data to be printed
</p>
<p><var>exts_size</var>: the number of available structures
</p>
<p><var>format</var>: Indicate the format to use
</p>
<p><var>out</var>: Newly allocated datum with null terminated string.
</p>
<p>This function will pretty print X.509 certificate extensions, 
suitable for display to a human.
</p>
<p>The output  <code>out</code> needs to be deallocated using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fkey_005fpurpose_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_key_purpose_deinit</h4>
<a name="gnutls_005fx509_005fkey_005fpurpose_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fkey_005fpurpose_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_key_purpose_deinit</strong> <em>(gnutls_x509_key_purposes_t <var>p</var>)</em></dt>
<dd><p><var>p</var>: The key purposes
</p>
<p>This function will deinitialize a key purposes type.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fkey_005fpurpose_005fget-1"></a>
<h4 class="subheading">gnutls_x509_key_purpose_get</h4>
<a name="gnutls_005fx509_005fkey_005fpurpose_005fget"></a><dl>
<dt><a name="index-gnutls_005fx509_005fkey_005fpurpose_005fget"></a>Function: <em>int</em> <strong>gnutls_x509_key_purpose_get</strong> <em>(gnutls_x509_key_purposes_t <var>p</var>, unsigned <var>idx</var>, gnutls_datum_t * <var>oid</var>)</em></dt>
<dd><p><var>p</var>: The key purposes
</p>
<p><var>idx</var>: The index of the key purpose to retrieve
</p>
<p><var>oid</var>: Will hold the object identifier of the key purpose (to be treated as constant)
</p>
<p>This function will retrieve the specified by the index key purpose in the
purposes type. The object identifier will be a null terminated string.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the index is out of bounds, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fkey_005fpurpose_005finit-1"></a>
<h4 class="subheading">gnutls_x509_key_purpose_init</h4>
<a name="gnutls_005fx509_005fkey_005fpurpose_005finit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fkey_005fpurpose_005finit"></a>Function: <em>int</em> <strong>gnutls_x509_key_purpose_init</strong> <em>(gnutls_x509_key_purposes_t * <var>p</var>)</em></dt>
<dd><p><var>p</var>: The key purposes
</p>
<p>This function will initialize an alternative names type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fkey_005fpurpose_005fset-1"></a>
<h4 class="subheading">gnutls_x509_key_purpose_set</h4>
<a name="gnutls_005fx509_005fkey_005fpurpose_005fset"></a><dl>
<dt><a name="index-gnutls_005fx509_005fkey_005fpurpose_005fset"></a>Function: <em>int</em> <strong>gnutls_x509_key_purpose_set</strong> <em>(gnutls_x509_key_purposes_t <var>p</var>, const char * <var>oid</var>)</em></dt>
<dd><p><var>p</var>: The key purposes
</p>
<p><var>oid</var>: The object identifier of the key purpose
</p>
<p>This function will store the specified key purpose in the
purposes.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0), otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fname_005fconstraints_005fadd_005fexcluded-1"></a>
<h4 class="subheading">gnutls_x509_name_constraints_add_excluded</h4>
<a name="gnutls_005fx509_005fname_005fconstraints_005fadd_005fexcluded"></a><dl>
<dt><a name="index-gnutls_005fx509_005fname_005fconstraints_005fadd_005fexcluded"></a>Function: <em>int</em> <strong>gnutls_x509_name_constraints_add_excluded</strong> <em>(gnutls_x509_name_constraints_t <var>nc</var>, gnutls_x509_subject_alt_name_t <var>type</var>, const gnutls_datum_t * <var>name</var>)</em></dt>
<dd><p><var>nc</var>: The nameconstraints
</p>
<p><var>type</var>: The type of the constraints
</p>
<p><var>name</var>: The data of the constraints
</p>
<p>This function will add a name constraint to the list of excluded
constraints.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fname_005fconstraints_005fadd_005fpermitted-1"></a>
<h4 class="subheading">gnutls_x509_name_constraints_add_permitted</h4>
<a name="gnutls_005fx509_005fname_005fconstraints_005fadd_005fpermitted"></a><dl>
<dt><a name="index-gnutls_005fx509_005fname_005fconstraints_005fadd_005fpermitted"></a>Function: <em>int</em> <strong>gnutls_x509_name_constraints_add_permitted</strong> <em>(gnutls_x509_name_constraints_t <var>nc</var>, gnutls_x509_subject_alt_name_t <var>type</var>, const gnutls_datum_t * <var>name</var>)</em></dt>
<dd><p><var>nc</var>: The nameconstraints
</p>
<p><var>type</var>: The type of the constraints
</p>
<p><var>name</var>: The data of the constraints
</p>
<p>This function will add a name constraint to the list of permitted
constraints.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fname_005fconstraints_005fcheck-1"></a>
<h4 class="subheading">gnutls_x509_name_constraints_check</h4>
<a name="gnutls_005fx509_005fname_005fconstraints_005fcheck"></a><dl>
<dt><a name="index-gnutls_005fx509_005fname_005fconstraints_005fcheck"></a>Function: <em>unsigned</em> <strong>gnutls_x509_name_constraints_check</strong> <em>(gnutls_x509_name_constraints_t <var>nc</var>, gnutls_x509_subject_alt_name_t <var>type</var>, const gnutls_datum_t * <var>name</var>)</em></dt>
<dd><p><var>nc</var>: the extracted name constraints
</p>
<p><var>type</var>: the type of the constraint to check (of type gnutls_x509_subject_alt_name_t)
</p>
<p><var>name</var>: the name to be checked
</p>
<p>This function will check the provided name against the constraints in
 <code>nc</code> using the RFC5280 rules. Currently this function is limited to DNS
names and emails (of type <code>GNUTLS_SAN_DNSNAME</code>  and <code>GNUTLS_SAN_RFC822NAME</code> ).
</p>
<p><strong>Returns:</strong> zero if the provided name is not acceptable, and non-zero otherwise.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fname_005fconstraints_005fcheck_005fcrt-1"></a>
<h4 class="subheading">gnutls_x509_name_constraints_check_crt</h4>
<a name="gnutls_005fx509_005fname_005fconstraints_005fcheck_005fcrt"></a><dl>
<dt><a name="index-gnutls_005fx509_005fname_005fconstraints_005fcheck_005fcrt"></a>Function: <em>unsigned</em> <strong>gnutls_x509_name_constraints_check_crt</strong> <em>(gnutls_x509_name_constraints_t <var>nc</var>, gnutls_x509_subject_alt_name_t <var>type</var>, gnutls_x509_crt_t <var>cert</var>)</em></dt>
<dd><p><var>nc</var>: the extracted name constraints
</p>
<p><var>type</var>: the type of the constraint to check (of type gnutls_x509_subject_alt_name_t)
</p>
<p><var>cert</var>: the certificate to be checked
</p>
<p>This function will check the provided certificate names against the constraints in
 <code>nc</code> using the RFC5280 rules. It will traverse all the certificate&rsquo;s names and
alternative names.
</p>
<p>Currently this function is limited to DNS
names and emails (of type <code>GNUTLS_SAN_DNSNAME</code>  and <code>GNUTLS_SAN_RFC822NAME</code> ).
</p>
<p><strong>Returns:</strong> zero if the provided name is not acceptable, and non-zero otherwise.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fname_005fconstraints_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_name_constraints_deinit</h4>
<a name="gnutls_005fx509_005fname_005fconstraints_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fname_005fconstraints_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_name_constraints_deinit</strong> <em>(gnutls_x509_name_constraints_t <var>nc</var>)</em></dt>
<dd><p><var>nc</var>: The nameconstraints
</p>
<p>This function will deinitialize a name constraints type.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fname_005fconstraints_005fget_005fexcluded-1"></a>
<h4 class="subheading">gnutls_x509_name_constraints_get_excluded</h4>
<a name="gnutls_005fx509_005fname_005fconstraints_005fget_005fexcluded"></a><dl>
<dt><a name="index-gnutls_005fx509_005fname_005fconstraints_005fget_005fexcluded"></a>Function: <em>int</em> <strong>gnutls_x509_name_constraints_get_excluded</strong> <em>(gnutls_x509_name_constraints_t <var>nc</var>, unsigned <var>idx</var>, unsigned * <var>type</var>, gnutls_datum_t * <var>name</var>)</em></dt>
<dd><p><var>nc</var>: the extracted name constraints
</p>
<p><var>idx</var>: the index of the constraint
</p>
<p><var>type</var>: the type of the constraint (of type gnutls_x509_subject_alt_name_t)
</p>
<p><var>name</var>: the name in the constraint (of the specific type)
</p>
<p>This function will return an intermediate type containing
the name constraints of the provided CA certificate. That
structure can be used in combination with <code>gnutls_x509_name_constraints_check()</code> 
to verify whether a server&rsquo;s name is in accordance with the constraints.
</p>
<p>The name should be treated as constant and valid for the lifetime of  <code>nc</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the extension is not present, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fname_005fconstraints_005fget_005fpermitted-1"></a>
<h4 class="subheading">gnutls_x509_name_constraints_get_permitted</h4>
<a name="gnutls_005fx509_005fname_005fconstraints_005fget_005fpermitted"></a><dl>
<dt><a name="index-gnutls_005fx509_005fname_005fconstraints_005fget_005fpermitted"></a>Function: <em>int</em> <strong>gnutls_x509_name_constraints_get_permitted</strong> <em>(gnutls_x509_name_constraints_t <var>nc</var>, unsigned <var>idx</var>, unsigned * <var>type</var>, gnutls_datum_t * <var>name</var>)</em></dt>
<dd><p><var>nc</var>: the extracted name constraints
</p>
<p><var>idx</var>: the index of the constraint
</p>
<p><var>type</var>: the type of the constraint (of type gnutls_x509_subject_alt_name_t)
</p>
<p><var>name</var>: the name in the constraint (of the specific type)
</p>
<p>This function will return an intermediate type containing
the name constraints of the provided CA certificate. That
structure can be used in combination with <code>gnutls_x509_name_constraints_check()</code> 
to verify whether a server&rsquo;s name is in accordance with the constraints.
</p>
<p>The name should be treated as constant and valid for the lifetime of  <code>nc</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the extension is not present, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fname_005fconstraints_005finit-1"></a>
<h4 class="subheading">gnutls_x509_name_constraints_init</h4>
<a name="gnutls_005fx509_005fname_005fconstraints_005finit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fname_005fconstraints_005finit"></a>Function: <em>int</em> <strong>gnutls_x509_name_constraints_init</strong> <em>(gnutls_x509_name_constraints_t * <var>nc</var>)</em></dt>
<dd><p><var>nc</var>: The nameconstraints
</p>
<p>This function will initialize a name constraints type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fothername_005fto_005fvirtual-1"></a>
<h4 class="subheading">gnutls_x509_othername_to_virtual</h4>
<a name="gnutls_005fx509_005fothername_005fto_005fvirtual"></a><dl>
<dt><a name="index-gnutls_005fx509_005fothername_005fto_005fvirtual"></a>Function: <em>int</em> <strong>gnutls_x509_othername_to_virtual</strong> <em>(const char * <var>oid</var>, const gnutls_datum_t * <var>othername</var>, unsigned int * <var>virt_type</var>, gnutls_datum_t * <var>virt</var>)</em></dt>
<dd><p><var>oid</var>: The othername object identifier
</p>
<p><var>othername</var>: The othername data
</p>
<p><var>virt_type</var>: GNUTLS_SAN_OTHERNAME_XXX
</p>
<p><var>virt</var>: allocated printable data
</p>
<p>This function will parse and convert the othername data to a virtual
type supported by gnutls.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.8
</p></dd></dl>

<a name="gnutls_005fx509_005fpolicies_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_policies_deinit</h4>
<a name="gnutls_005fx509_005fpolicies_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fpolicies_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_policies_deinit</strong> <em>(gnutls_x509_policies_t <var>policies</var>)</em></dt>
<dd><p><var>policies</var>: The authority key identifier
</p>
<p>This function will deinitialize an authority key identifier type.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fpolicies_005fget-1"></a>
<h4 class="subheading">gnutls_x509_policies_get</h4>
<a name="gnutls_005fx509_005fpolicies_005fget"></a><dl>
<dt><a name="index-gnutls_005fx509_005fpolicies_005fget"></a>Function: <em>int</em> <strong>gnutls_x509_policies_get</strong> <em>(gnutls_x509_policies_t <var>policies</var>, unsigned int <var>seq</var>, struct gnutls_x509_policy_st * <var>policy</var>)</em></dt>
<dd><p><var>policies</var>: The policies
</p>
<p><var>seq</var>: The index of the name to get
</p>
<p><var>policy</var>: Will hold the policy
</p>
<p>This function will return a specific policy as stored in
the  <code>policies</code> type. The returned values should be treated as constant
and valid for the lifetime of  <code>policies</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
if the index is out of bounds, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fpolicies_005finit-1"></a>
<h4 class="subheading">gnutls_x509_policies_init</h4>
<a name="gnutls_005fx509_005fpolicies_005finit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fpolicies_005finit"></a>Function: <em>int</em> <strong>gnutls_x509_policies_init</strong> <em>(gnutls_x509_policies_t * <var>policies</var>)</em></dt>
<dd><p><var>policies</var>: The authority key ID
</p>
<p>This function will initialize an authority key ID type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fpolicies_005fset-1"></a>
<h4 class="subheading">gnutls_x509_policies_set</h4>
<a name="gnutls_005fx509_005fpolicies_005fset"></a><dl>
<dt><a name="index-gnutls_005fx509_005fpolicies_005fset"></a>Function: <em>int</em> <strong>gnutls_x509_policies_set</strong> <em>(gnutls_x509_policies_t <var>policies</var>, const struct gnutls_x509_policy_st * <var>policy</var>)</em></dt>
<dd><p><var>policies</var>: An initialized policies
</p>
<p><var>policy</var>: Contains the policy to set
</p>
<p>This function will store the specified policy in
the provided  <code>policies</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0), otherwise a negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fpolicy_005frelease-1"></a>
<h4 class="subheading">gnutls_x509_policy_release</h4>
<a name="gnutls_005fx509_005fpolicy_005frelease"></a><dl>
<dt><a name="index-gnutls_005fx509_005fpolicy_005frelease"></a>Function: <em>void</em> <strong>gnutls_x509_policy_release</strong> <em>(struct gnutls_x509_policy_st * <var>policy</var>)</em></dt>
<dd><p><var>policy</var>: a certificate policy
</p>
<p>This function will deinitialize all memory associated with the provided
 <code>policy</code> . The policy is allocated using <code>gnutls_x509_crt_get_policy()</code> .
</p>
<p><strong>Since:</strong> 3.1.5
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fcpy-1"></a>
<h4 class="subheading">gnutls_x509_privkey_cpy</h4>
<a name="gnutls_005fx509_005fprivkey_005fcpy"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fcpy"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_cpy</strong> <em>(gnutls_x509_privkey_t <var>dst</var>, gnutls_x509_privkey_t <var>src</var>)</em></dt>
<dd><p><var>dst</var>: The destination key, which should be initialized.
</p>
<p><var>src</var>: The source key
</p>
<p>This function will copy a private key from source to destination
key. Destination has to be initialized.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_privkey_deinit</h4>
<a name="gnutls_005fx509_005fprivkey_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_privkey_deinit</strong> <em>(gnutls_x509_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: The key to be deinitialized
</p>
<p>This function will deinitialize a private key structure.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fexport-1"></a>
<h4 class="subheading">gnutls_x509_privkey_export</h4>
<a name="gnutls_005fx509_005fprivkey_005fexport"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fexport"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_export</strong> <em>(gnutls_x509_privkey_t <var>key</var>, gnutls_x509_crt_fmt_t <var>format</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>key</var>: Holds the key
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>output_data</var>: will contain a private key PEM or DER encoded
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will export the private key to a PKCS1 structure for
RSA keys, or an integer sequence for DSA keys.  The DSA keys are in
the same format with the parameters used by openssl.
</p>
<p>If the buffer provided is not long enough to hold the output, then
* <code>output_data_size</code> is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code> 
will be returned.
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN RSA PRIVATE KEY&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fexport2-1"></a>
<h4 class="subheading">gnutls_x509_privkey_export2</h4>
<a name="gnutls_005fx509_005fprivkey_005fexport2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fexport2"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_export2</strong> <em>(gnutls_x509_privkey_t <var>key</var>, gnutls_x509_crt_fmt_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>key</var>: Holds the key
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>out</var>: will contain a private key PEM or DER encoded
</p>
<p>This function will export the private key to a PKCS1 structure for
RSA keys, or an integer sequence for DSA keys.  The DSA keys are in
the same format with the parameters used by openssl.
</p>
<p>The output buffer is allocated using <code>gnutls_malloc()</code> .
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN RSA PRIVATE KEY&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p>Since 3.1.3
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fexport2_005fpkcs8-1"></a>
<h4 class="subheading">gnutls_x509_privkey_export2_pkcs8</h4>
<a name="gnutls_005fx509_005fprivkey_005fexport2_005fpkcs8"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fexport2_005fpkcs8"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_export2_pkcs8</strong> <em>(gnutls_x509_privkey_t <var>key</var>, gnutls_x509_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>key</var>: Holds the key
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>password</var>: the password that will be used to encrypt the key.
</p>
<p><var>flags</var>: an ORed sequence of gnutls_pkcs_encrypt_flags_t
</p>
<p><var>out</var>: will contain a private key PEM or DER encoded
</p>
<p>This function will export the private key to a PKCS8 structure.
Both RSA and DSA keys can be exported. For DSA keys we use
PKCS <code>11</code>  definitions. If the flags do not specify the encryption
cipher, then the default 3DES (PBES2) will be used.
</p>
<p>The  <code>password</code> can be either ASCII or UTF-8 in the default PBES2
encryption schemas, or ASCII for the PKCS12 schemas.
</p>
<p>The output buffer is allocated using <code>gnutls_malloc()</code> .
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN ENCRYPTED PRIVATE KEY&quot; or &quot;BEGIN PRIVATE KEY&quot; if
encryption is not used.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p>
<p>Since 3.1.3
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fexport_005fdsa_005fraw-1"></a>
<h4 class="subheading">gnutls_x509_privkey_export_dsa_raw</h4>
<a name="gnutls_005fx509_005fprivkey_005fexport_005fdsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fexport_005fdsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_export_dsa_raw</strong> <em>(gnutls_x509_privkey_t <var>key</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>g</var>, gnutls_datum_t * <var>y</var>, gnutls_datum_t * <var>x</var>)</em></dt>
<dd><p><var>key</var>: a key
</p>
<p><var>p</var>: will hold the p
</p>
<p><var>q</var>: will hold the q
</p>
<p><var>g</var>: will hold the g
</p>
<p><var>y</var>: will hold the y
</p>
<p><var>x</var>: will hold the x
</p>
<p>This function will export the DSA private key&rsquo;s parameters found
in the given structure. The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fexport_005fecc_005fraw-1"></a>
<h4 class="subheading">gnutls_x509_privkey_export_ecc_raw</h4>
<a name="gnutls_005fx509_005fprivkey_005fexport_005fecc_005fraw"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fexport_005fecc_005fraw"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_export_ecc_raw</strong> <em>(gnutls_x509_privkey_t <var>key</var>, gnutls_ecc_curve_t * <var>curve</var>, gnutls_datum_t * <var>x</var>, gnutls_datum_t * <var>y</var>, gnutls_datum_t * <var>k</var>)</em></dt>
<dd><p><var>key</var>: a key
</p>
<p><var>curve</var>: will hold the curve
</p>
<p><var>x</var>: will hold the x coordinate
</p>
<p><var>y</var>: will hold the y coordinate
</p>
<p><var>k</var>: will hold the private key
</p>
<p>This function will export the ECC private key&rsquo;s parameters found
in the given structure. The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fexport_005fpkcs8-1"></a>
<h4 class="subheading">gnutls_x509_privkey_export_pkcs8</h4>
<a name="gnutls_005fx509_005fprivkey_005fexport_005fpkcs8"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fexport_005fpkcs8"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_export_pkcs8</strong> <em>(gnutls_x509_privkey_t <var>key</var>, gnutls_x509_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>key</var>: Holds the key
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>password</var>: the password that will be used to encrypt the key.
</p>
<p><var>flags</var>: an ORed sequence of gnutls_pkcs_encrypt_flags_t
</p>
<p><var>output_data</var>: will contain a private key PEM or DER encoded
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will export the private key to a PKCS8 structure.
Both RSA and DSA keys can be exported. For DSA keys we use
PKCS <code>11</code>  definitions. If the flags do not specify the encryption
cipher, then the default 3DES (PBES2) will be used.
</p>
<p>The  <code>password</code> can be either ASCII or UTF-8 in the default PBES2
encryption schemas, or ASCII for the PKCS12 schemas.
</p>
<p>If the buffer provided is not long enough to hold the output, then
*output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
be returned.
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN ENCRYPTED PRIVATE KEY&quot; or &quot;BEGIN PRIVATE KEY&quot; if
encryption is not used.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fexport_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_x509_privkey_export_rsa_raw</h4>
<a name="gnutls_005fx509_005fprivkey_005fexport_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fexport_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_export_rsa_raw</strong> <em>(gnutls_x509_privkey_t <var>key</var>, gnutls_datum_t * <var>m</var>, gnutls_datum_t * <var>e</var>, gnutls_datum_t * <var>d</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>u</var>)</em></dt>
<dd><p><var>key</var>: a key
</p>
<p><var>m</var>: will hold the modulus
</p>
<p><var>e</var>: will hold the public exponent
</p>
<p><var>d</var>: will hold the private exponent
</p>
<p><var>p</var>: will hold the first prime (p)
</p>
<p><var>q</var>: will hold the second prime (q)
</p>
<p><var>u</var>: will hold the coefficient
</p>
<p>This function will export the RSA private key&rsquo;s parameters found
in the given structure. The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fexport_005frsa_005fraw2-1"></a>
<h4 class="subheading">gnutls_x509_privkey_export_rsa_raw2</h4>
<a name="gnutls_005fx509_005fprivkey_005fexport_005frsa_005fraw2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fexport_005frsa_005fraw2"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_export_rsa_raw2</strong> <em>(gnutls_x509_privkey_t <var>key</var>, gnutls_datum_t * <var>m</var>, gnutls_datum_t * <var>e</var>, gnutls_datum_t * <var>d</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>u</var>, gnutls_datum_t * <var>e1</var>, gnutls_datum_t * <var>e2</var>)</em></dt>
<dd><p><var>key</var>: a key
</p>
<p><var>m</var>: will hold the modulus
</p>
<p><var>e</var>: will hold the public exponent
</p>
<p><var>d</var>: will hold the private exponent
</p>
<p><var>p</var>: will hold the first prime (p)
</p>
<p><var>q</var>: will hold the second prime (q)
</p>
<p><var>u</var>: will hold the coefficient
</p>
<p><var>e1</var>: will hold e1 = d mod (p-1)
</p>
<p><var>e2</var>: will hold e2 = d mod (q-1)
</p>
<p>This function will export the RSA private key&rsquo;s parameters found
in the given structure. The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005ffix-1"></a>
<h4 class="subheading">gnutls_x509_privkey_fix</h4>
<a name="gnutls_005fx509_005fprivkey_005ffix"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005ffix"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_fix</strong> <em>(gnutls_x509_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: a key
</p>
<p>This function will recalculate the secondary parameters in a key.
In RSA keys, this can be the coefficient and exponent1,2.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fgenerate-1"></a>
<h4 class="subheading">gnutls_x509_privkey_generate</h4>
<a name="gnutls_005fx509_005fprivkey_005fgenerate"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fgenerate"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_generate</strong> <em>(gnutls_x509_privkey_t <var>key</var>, gnutls_pk_algorithm_t <var>algo</var>, unsigned int <var>bits</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: a key
</p>
<p><var>algo</var>: is one of the algorithms in <code>gnutls_pk_algorithm_t</code> .
</p>
<p><var>bits</var>: the size of the modulus
</p>
<p><var>flags</var>: unused for now.  Must be 0.
</p>
<p>This function will generate a random private key. Note that this
function must be called on an empty private key.
</p>
<p>Note that when generating an elliptic curve key, the curve
can be substituted in the place of the bits parameter using the
<code>GNUTLS_CURVE_TO_BITS()</code>  macro.
</p>
<p>For DSA keys, if the subgroup size needs to be specified check
the <code>GNUTLS_SUBGROUP_TO_BITS()</code>  macro.
</p>
<p>Do not set the number of bits directly, use <code>gnutls_sec_param_to_pk_bits()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fget_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_privkey_get_key_id</h4>
<a name="gnutls_005fx509_005fprivkey_005fget_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fget_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_get_key_id</strong> <em>(gnutls_x509_privkey_t <var>key</var>, unsigned int <var>flags</var>, unsigned char * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>key</var>: a key
</p>
<p><var>flags</var>: should be one of the flags from <code>gnutls_keyid_flags_t</code> 
</p>
<p><var>output_data</var>: will contain the key ID
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will return a unique ID that depends on the public key
parameters. This ID can be used in checking whether a certificate
corresponds to the given key.
</p>
<p>If the buffer provided is not long enough to hold the output, then
* <code>output_data_size</code> is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  will
be returned.  The output will normally be a SHA-1 hash output,
which is 20 bytes.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fget_005fpk_005falgorithm-1"></a>
<h4 class="subheading">gnutls_x509_privkey_get_pk_algorithm</h4>
<a name="gnutls_005fx509_005fprivkey_005fget_005fpk_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fget_005fpk_005falgorithm"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_get_pk_algorithm</strong> <em>(gnutls_x509_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: should contain a <code>gnutls_x509_privkey_t</code>  type
</p>
<p>This function will return the public key algorithm of a private
key.
</p>
<p><strong>Returns:</strong> a member of the <code>gnutls_pk_algorithm_t</code>  enumeration on
success, or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fget_005fpk_005falgorithm2-1"></a>
<h4 class="subheading">gnutls_x509_privkey_get_pk_algorithm2</h4>
<a name="gnutls_005fx509_005fprivkey_005fget_005fpk_005falgorithm2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fget_005fpk_005falgorithm2"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_get_pk_algorithm2</strong> <em>(gnutls_x509_privkey_t <var>key</var>, unsigned int * <var>bits</var>)</em></dt>
<dd><p><var>key</var>: should contain a <code>gnutls_x509_privkey_t</code>  type
</p>
<p><var>bits</var>: The number of bits in the public key algorithm
</p>
<p>This function will return the public key algorithm of a private
key.
</p>
<p><strong>Returns:</strong> a member of the <code>gnutls_pk_algorithm_t</code>  enumeration on
success, or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fimport-1"></a>
<h4 class="subheading">gnutls_x509_privkey_import</h4>
<a name="gnutls_005fx509_005fprivkey_005fimport"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fimport"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_import</strong> <em>(gnutls_x509_privkey_t <var>key</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>key</var>: The data to store the parsed key
</p>
<p><var>data</var>: The DER or PEM encoded certificate.
</p>
<p><var>format</var>: One of DER or PEM
</p>
<p>This function will convert the given DER or PEM encoded key to the
native <code>gnutls_x509_privkey_t</code>  format. The output will be stored in
 <code>key</code> .
</p>
<p>If the key is PEM encoded it should have a header that contains &quot;PRIVATE
KEY&quot;. Note that this function falls back to PKCS <code>8</code>  decoding without
password, if the default format fails to import.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fimport2-1"></a>
<h4 class="subheading">gnutls_x509_privkey_import2</h4>
<a name="gnutls_005fx509_005fprivkey_005fimport2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fimport2-1"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_import2</strong> <em>(gnutls_x509_privkey_t <var>key</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: The data to store the parsed key
</p>
<p><var>data</var>: The DER or PEM encoded key.
</p>
<p><var>format</var>: One of DER or PEM
</p>
<p><var>password</var>: A password (optional)
</p>
<p><var>flags</var>: an ORed sequence of gnutls_pkcs_encrypt_flags_t
</p>
<p>This function will import the given DER or PEM encoded key, to 
the native <code>gnutls_x509_privkey_t</code>  format, irrespective of the
input format. The input format is auto-detected.
</p>
<p>The supported formats are basic unencrypted key, PKCS8, PKCS12,
and the openssl format.
</p>
<p>If the provided key is encrypted but no password was given, then
<code>GNUTLS_E_DECRYPTION_FAILED</code>  is returned. Since GnuTLS 3.4.0 this
function will utilize the PIN callbacks if any.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fimport_005fdsa_005fraw-1"></a>
<h4 class="subheading">gnutls_x509_privkey_import_dsa_raw</h4>
<a name="gnutls_005fx509_005fprivkey_005fimport_005fdsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fimport_005fdsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_import_dsa_raw</strong> <em>(gnutls_x509_privkey_t <var>key</var>, const gnutls_datum_t * <var>p</var>, const gnutls_datum_t * <var>q</var>, const gnutls_datum_t * <var>g</var>, const gnutls_datum_t * <var>y</var>, const gnutls_datum_t * <var>x</var>)</em></dt>
<dd><p><var>key</var>: The data to store the parsed key
</p>
<p><var>p</var>: holds the p
</p>
<p><var>q</var>: holds the q
</p>
<p><var>g</var>: holds the g
</p>
<p><var>y</var>: holds the y
</p>
<p><var>x</var>: holds the x
</p>
<p>This function will convert the given DSA raw parameters to the
native <code>gnutls_x509_privkey_t</code>  format.  The output will be stored
in  <code>key</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fimport_005fecc_005fraw-1"></a>
<h4 class="subheading">gnutls_x509_privkey_import_ecc_raw</h4>
<a name="gnutls_005fx509_005fprivkey_005fimport_005fecc_005fraw"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fimport_005fecc_005fraw"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_import_ecc_raw</strong> <em>(gnutls_x509_privkey_t <var>key</var>, gnutls_ecc_curve_t <var>curve</var>, const gnutls_datum_t * <var>x</var>, const gnutls_datum_t * <var>y</var>, const gnutls_datum_t * <var>k</var>)</em></dt>
<dd><p><var>key</var>: The data to store the parsed key
</p>
<p><var>curve</var>: holds the curve
</p>
<p><var>x</var>: holds the x
</p>
<p><var>y</var>: holds the y
</p>
<p><var>k</var>: holds the k
</p>
<p>This function will convert the given elliptic curve parameters to the
native <code>gnutls_x509_privkey_t</code>  format.  The output will be stored
in  <code>key</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fimport_005fopenssl-1"></a>
<h4 class="subheading">gnutls_x509_privkey_import_openssl</h4>
<a name="gnutls_005fx509_005fprivkey_005fimport_005fopenssl"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fimport_005fopenssl-1"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_import_openssl</strong> <em>(gnutls_x509_privkey_t <var>key</var>, const gnutls_datum_t * <var>data</var>, const char * <var>password</var>)</em></dt>
<dd><p><var>key</var>: The data to store the parsed key
</p>
<p><var>data</var>: The DER or PEM encoded key.
</p>
<p><var>password</var>: the password to decrypt the key (if it is encrypted).
</p>
<p>This function will convert the given PEM encrypted to 
the native gnutls_x509_privkey_t format. The
output will be stored in  <code>key</code> .  
</p>
<p>The  <code>password</code> should be in ASCII. If the password is not provided
or wrong then <code>GNUTLS_E_DECRYPTION_FAILED</code>  will be returned.
</p>
<p>If the Certificate is PEM encoded it should have a header of
&quot;PRIVATE KEY&quot; and the &quot;DEK-Info&quot; header. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fimport_005fpkcs8-1"></a>
<h4 class="subheading">gnutls_x509_privkey_import_pkcs8</h4>
<a name="gnutls_005fx509_005fprivkey_005fimport_005fpkcs8"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fimport_005fpkcs8"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_import_pkcs8</strong> <em>(gnutls_x509_privkey_t <var>key</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: The data to store the parsed key
</p>
<p><var>data</var>: The DER or PEM encoded key.
</p>
<p><var>format</var>: One of DER or PEM
</p>
<p><var>password</var>: the password to decrypt the key (if it is encrypted).
</p>
<p><var>flags</var>: 0 if encrypted or GNUTLS_PKCS_PLAIN if not encrypted.
</p>
<p>This function will convert the given DER or PEM encoded PKCS8 2.0
encrypted key to the native gnutls_x509_privkey_t format. The
output will be stored in  <code>key</code> .  Both RSA and DSA keys can be
imported, and flags can only be used to indicate an unencrypted
key.
</p>
<p>The  <code>password</code> can be either ASCII or UTF-8 in the default PBES2
encryption schemas, or ASCII for the PKCS12 schemas.
</p>
<p>If the Certificate is PEM encoded it should have a header of
&quot;ENCRYPTED PRIVATE KEY&quot;, or &quot;PRIVATE KEY&quot;. You only need to
specify the flags if the key is DER encoded, since in that case
the encryption status cannot be auto-detected.
</p>
<p>If the <code>GNUTLS_PKCS_PLAIN</code>  flag is specified and the supplied data
are encrypted then <code>GNUTLS_E_DECRYPTION_FAILED</code>  is returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fimport_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_x509_privkey_import_rsa_raw</h4>
<a name="gnutls_005fx509_005fprivkey_005fimport_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fimport_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_import_rsa_raw</strong> <em>(gnutls_x509_privkey_t <var>key</var>, const gnutls_datum_t * <var>m</var>, const gnutls_datum_t * <var>e</var>, const gnutls_datum_t * <var>d</var>, const gnutls_datum_t * <var>p</var>, const gnutls_datum_t * <var>q</var>, const gnutls_datum_t * <var>u</var>)</em></dt>
<dd><p><var>key</var>: The data to store the parsed key
</p>
<p><var>m</var>: holds the modulus
</p>
<p><var>e</var>: holds the public exponent
</p>
<p><var>d</var>: holds the private exponent
</p>
<p><var>p</var>: holds the first prime (p)
</p>
<p><var>q</var>: holds the second prime (q)
</p>
<p><var>u</var>: holds the coefficient
</p>
<p>This function will convert the given RSA raw parameters to the
native <code>gnutls_x509_privkey_t</code>  format.  The output will be stored in
 <code>key</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fimport_005frsa_005fraw2-1"></a>
<h4 class="subheading">gnutls_x509_privkey_import_rsa_raw2</h4>
<a name="gnutls_005fx509_005fprivkey_005fimport_005frsa_005fraw2"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fimport_005frsa_005fraw2"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_import_rsa_raw2</strong> <em>(gnutls_x509_privkey_t <var>key</var>, const gnutls_datum_t * <var>m</var>, const gnutls_datum_t * <var>e</var>, const gnutls_datum_t * <var>d</var>, const gnutls_datum_t * <var>p</var>, const gnutls_datum_t * <var>q</var>, const gnutls_datum_t * <var>u</var>, const gnutls_datum_t * <var>e1</var>, const gnutls_datum_t * <var>e2</var>)</em></dt>
<dd><p><var>key</var>: The data to store the parsed key
</p>
<p><var>m</var>: holds the modulus
</p>
<p><var>e</var>: holds the public exponent
</p>
<p><var>d</var>: holds the private exponent
</p>
<p><var>p</var>: holds the first prime (p)
</p>
<p><var>q</var>: holds the second prime (q)
</p>
<p><var>u</var>: holds the coefficient (optional)
</p>
<p><var>e1</var>: holds e1 = d mod (p-1) (optional)
</p>
<p><var>e2</var>: holds e2 = d mod (q-1) (optional)
</p>
<p>This function will convert the given RSA raw parameters to the
native <code>gnutls_x509_privkey_t</code>  format.  The output will be stored in
 <code>key</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005finit-1"></a>
<h4 class="subheading">gnutls_x509_privkey_init</h4>
<a name="gnutls_005fx509_005fprivkey_005finit"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005finit"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_init</strong> <em>(gnutls_x509_privkey_t * <var>key</var>)</em></dt>
<dd><p><var>key</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize a private key type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fsec_005fparam-1"></a>
<h4 class="subheading">gnutls_x509_privkey_sec_param</h4>
<a name="gnutls_005fx509_005fprivkey_005fsec_005fparam"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fsec_005fparam"></a>Function: <em>gnutls_sec_param_t</em> <strong>gnutls_x509_privkey_sec_param</strong> <em>(gnutls_x509_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: a key
</p>
<p>This function will return the security parameter appropriate with
this private key.
</p>
<p><strong>Returns:</strong> On success, a valid security parameter is returned otherwise
<code>GNUTLS_SEC_PARAM_UNKNOWN</code>  is returned.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fset_005fpin_005ffunction-1"></a>
<h4 class="subheading">gnutls_x509_privkey_set_pin_function</h4>
<a name="gnutls_005fx509_005fprivkey_005fset_005fpin_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fset_005fpin_005ffunction"></a>Function: <em>void</em> <strong>gnutls_x509_privkey_set_pin_function</strong> <em>(gnutls_x509_privkey_t <var>privkey</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</em></dt>
<dd><p><var>privkey</var>: The certificate structure
</p>
<p><var>fn</var>: the callback
</p>
<p><var>userdata</var>: data associated with the callback
</p>
<p>This function will set a callback function to be used when
it is required to access a protected object. This function overrides 
the global function set using <code>gnutls_pkcs11_set_pin_function()</code> .
</p>
<p>Note that this callback is used when decrypting a key.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fsign_005fdata-1"></a>
<h4 class="subheading">gnutls_x509_privkey_sign_data</h4>
<a name="gnutls_005fx509_005fprivkey_005fsign_005fdata"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fsign_005fdata"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_sign_data</strong> <em>(gnutls_x509_privkey_t <var>key</var>, gnutls_digest_algorithm_t <var>digest</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>data</var>, void * <var>signature</var>, size_t * <var>signature_size</var>)</em></dt>
<dd><p><var>key</var>: a key
</p>
<p><var>digest</var>: should be MD5 or SHA1
</p>
<p><var>flags</var>: should be 0 for now
</p>
<p><var>data</var>: holds the data to be signed
</p>
<p><var>signature</var>: will contain the signature
</p>
<p><var>signature_size</var>: holds the size of signature (and will be replaced
by the new size)
</p>
<p>This function will sign the given data using a signature algorithm
supported by the private key. Signature algorithms are always used
together with a hash functions.  Different hash functions may be
used for the RSA algorithm, but only SHA-1 for the DSA keys.
</p>
<p>If the buffer provided is not long enough to hold the output, then
* <code>signature_size</code> is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  will
be returned.
</p>
<p>Use <code>gnutls_x509_crt_get_preferred_hash_algorithm()</code>  to determine
the hash algorithm.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fverify_005fparams-1"></a>
<h4 class="subheading">gnutls_x509_privkey_verify_params</h4>
<a name="gnutls_005fx509_005fprivkey_005fverify_005fparams"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fverify_005fparams"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_verify_params</strong> <em>(gnutls_x509_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: a key
</p>
<p>This function will verify the private key parameters.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005frdn_005fget-1"></a>
<h4 class="subheading">gnutls_x509_rdn_get</h4>
<a name="gnutls_005fx509_005frdn_005fget"></a><dl>
<dt><a name="index-gnutls_005fx509_005frdn_005fget"></a>Function: <em>int</em> <strong>gnutls_x509_rdn_get</strong> <em>(const gnutls_datum_t * <var>idn</var>, char * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>idn</var>: should contain a DER encoded RDN sequence
</p>
<p><var>buf</var>: a pointer to a structure to hold the peer&rsquo;s name
</p>
<p><var>buf_size</var>: holds the size of  <code>buf</code> 
</p>
<p>This function will return the name of the given RDN sequence.  The
name will be in the form &quot;C=xxxx,O=yyyy,CN=zzzz&quot; as described in
RFC4514.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  is returned and * <code>buf_size</code> is
updated if the provided buffer is not long enough, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005frdn_005fget_005fby_005foid-1"></a>
<h4 class="subheading">gnutls_x509_rdn_get_by_oid</h4>
<a name="gnutls_005fx509_005frdn_005fget_005fby_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005frdn_005fget_005fby_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_rdn_get_by_oid</strong> <em>(const gnutls_datum_t * <var>idn</var>, const char * <var>oid</var>, int <var>indx</var>, unsigned int <var>raw_flag</var>, void * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>idn</var>: should contain a DER encoded RDN sequence
</p>
<p><var>oid</var>: an Object Identifier
</p>
<p><var>indx</var>: In case multiple same OIDs exist in the RDN indicates which
to send. Use 0 for the first one.
</p>
<p><var>raw_flag</var>: If non-zero then the raw DER data are returned.
</p>
<p><var>buf</var>: a pointer to a structure to hold the peer&rsquo;s name
</p>
<p><var>buf_size</var>: holds the size of  <code>buf</code> 
</p>
<p>This function will return the name of the given Object identifier,
of the RDN sequence.  The name will be encoded using the rules
from RFC4514.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  is returned and * <code>buf_size</code> is
updated if the provided buffer is not long enough, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005frdn_005fget_005foid-1"></a>
<h4 class="subheading">gnutls_x509_rdn_get_oid</h4>
<a name="gnutls_005fx509_005frdn_005fget_005foid"></a><dl>
<dt><a name="index-gnutls_005fx509_005frdn_005fget_005foid"></a>Function: <em>int</em> <strong>gnutls_x509_rdn_get_oid</strong> <em>(const gnutls_datum_t * <var>idn</var>, int <var>indx</var>, void * <var>buf</var>, size_t * <var>buf_size</var>)</em></dt>
<dd><p><var>idn</var>: should contain a DER encoded RDN sequence
</p>
<p><var>indx</var>: Indicates which OID to return. Use 0 for the first one.
</p>
<p><var>buf</var>: a pointer to a structure to hold the peer&rsquo;s name OID
</p>
<p><var>buf_size</var>: holds the size of  <code>buf</code> 
</p>
<p>This function will return the specified Object identifier, of the
RDN sequence.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, or
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  is returned and * <code>buf_size</code> is
updated if the provided buffer is not long enough, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005fcas-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_add_cas</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005fcas"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005fcas-1"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_cas</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const gnutls_x509_crt_t * <var>clist</var>, unsigned <var>clist_size</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>clist</var>: A list of CAs
</p>
<p><var>clist_size</var>: The length of the CA list
</p>
<p><var>flags</var>: should be 0 or an or&rsquo;ed sequence of <code>GNUTLS_TL</code>  options.
</p>
<p>This function will add the given certificate authorities
to the trusted list. The list of CAs must not be deinitialized
during this structure&rsquo;s lifetime.
</p>
<p>If the flag <code>GNUTLS_TL_NO_DUPLICATES</code>  is specified, then
the provided  <code>clist</code> entries that are duplicates will not be
added to the list and will be deinitialized.
</p>
<p><strong>Returns:</strong> The number of added elements is returned.
</p>
<p><strong>Since:</strong> 3.0.0
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005fcrls-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_add_crls</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005fcrls"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005fcrls-1"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_crls</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const gnutls_x509_crl_t * <var>crl_list</var>, int <var>crl_size</var>, unsigned int <var>flags</var>, unsigned int <var>verification_flags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>crl_list</var>: A list of CRLs
</p>
<p><var>crl_size</var>: The length of the CRL list
</p>
<p><var>flags</var>: if GNUTLS_TL_VERIFY_CRL is given the CRLs will be verified before being added.
</p>
<p><var>verification_flags</var>: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL
</p>
<p>This function will add the given certificate revocation lists
to the trusted list. The list of CRLs must not be deinitialized
during this structure&rsquo;s lifetime.
</p>
<p>This function must be called after <code>gnutls_x509_trust_list_add_cas()</code> 
to allow verifying the CRLs for validity. If the flag <code>GNUTLS_TL_NO_DUPLICATES</code> 
is given, then any provided CRLs that are a duplicate, will be deinitialized
and not added to the list (that assumes that <code>gnutls_x509_trust_list_deinit()</code> 
will be called with all=1).
</p>
<p><strong>Returns:</strong> The number of added elements is returned.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005fnamed_005fcrt-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_add_named_crt</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005fnamed_005fcrt"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005fnamed_005fcrt-1"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_named_crt</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, gnutls_x509_crt_t <var>cert</var>, const void * <var>name</var>, size_t <var>name_size</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>cert</var>: A certificate
</p>
<p><var>name</var>: An identifier for the certificate
</p>
<p><var>name_size</var>: The size of the identifier
</p>
<p><var>flags</var>: should be 0.
</p>
<p>This function will add the given certificate to the trusted
list and associate it with a name. The certificate will not be
be used for verification with <code>gnutls_x509_trust_list_verify_crt()</code> 
but with <code>gnutls_x509_trust_list_verify_named_crt()</code>  or
<code>gnutls_x509_trust_list_verify_crt2()</code>  - the latter only since
GnuTLS 3.4.0 and if a hostname is provided.
</p>
<p>In principle this function can be used to set individual &quot;server&quot;
certificates that are trusted by the user for that specific server
but for no other purposes.
</p>
<p>The certificate must not be deinitialized during the lifetime
of the trusted list.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0.0
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005fsystem_005ftrust-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_add_system_trust</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005fsystem_005ftrust"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005fsystem_005ftrust-1"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_system_trust</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, unsigned int <var>tl_flags</var>, unsigned int <var>tl_vflags</var>)</em></dt>
<dd><p><var>list</var>: The structure of the list
</p>
<p><var>tl_flags</var>: GNUTLS_TL_*
</p>
<p><var>tl_vflags</var>: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL
</p>
<p>This function adds the system&rsquo;s default trusted certificate
authorities to the trusted list. Note that on unsupported systems
this function returns <code>GNUTLS_E_UNIMPLEMENTED_FEATURE</code> .
</p>
<p>This function implies the flag <code>GNUTLS_TL_NO_DUPLICATES</code> .
</p>
<p><strong>Returns:</strong> The number of added elements or a negative error code on error.
</p>
<p><strong>Since:</strong> 3.1
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005fdir-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_add_trust_dir</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005fdir"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005fdir"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_trust_dir</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const char * <var>ca_dir</var>, const char * <var>crl_dir</var>, gnutls_x509_crt_fmt_t <var>type</var>, unsigned int <var>tl_flags</var>, unsigned int <var>tl_vflags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>ca_dir</var>: A directory containing the CAs (optional)
</p>
<p><var>crl_dir</var>: A directory containing a list of CRLs (optional)
</p>
<p><var>type</var>: The format of the certificates
</p>
<p><var>tl_flags</var>: GNUTLS_TL_*
</p>
<p><var>tl_vflags</var>: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL
</p>
<p>This function will add the given certificate authorities
to the trusted list. Only directories are accepted by
this function.
</p>
<p><strong>Returns:</strong> The number of added elements is returned.
</p>
<p><strong>Since:</strong> 3.3.6
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005ffile-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_add_trust_file</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005ffile"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005ffile-1"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_trust_file</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const char * <var>ca_file</var>, const char * <var>crl_file</var>, gnutls_x509_crt_fmt_t <var>type</var>, unsigned int <var>tl_flags</var>, unsigned int <var>tl_vflags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>ca_file</var>: A file containing a list of CAs (optional)
</p>
<p><var>crl_file</var>: A file containing a list of CRLs (optional)
</p>
<p><var>type</var>: The format of the certificates
</p>
<p><var>tl_flags</var>: GNUTLS_TL_*
</p>
<p><var>tl_vflags</var>: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL
</p>
<p>This function will add the given certificate authorities
to the trusted list. PKCS <code>11</code>  URLs are also accepted, instead
of files, by this function. A PKCS <code>11</code>  URL implies a trust
database (a specially marked module in p11-kit); the URL &quot;pkcs11:&quot;
implies all trust databases in the system. Only a single URL specifying
trust databases can be set; they cannot be stacked with multiple calls.
</p>
<p><strong>Returns:</strong> The number of added elements is returned.
</p>
<p><strong>Since:</strong> 3.1
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005fmem-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_add_trust_mem</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005fmem"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005fmem-1"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_add_trust_mem</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const gnutls_datum_t * <var>cas</var>, const gnutls_datum_t * <var>crls</var>, gnutls_x509_crt_fmt_t <var>type</var>, unsigned int <var>tl_flags</var>, unsigned int <var>tl_vflags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>cas</var>: A buffer containing a list of CAs (optional)
</p>
<p><var>crls</var>: A buffer containing a list of CRLs (optional)
</p>
<p><var>type</var>: The format of the certificates
</p>
<p><var>tl_flags</var>: GNUTLS_TL_*
</p>
<p><var>tl_vflags</var>: gnutls_certificate_verify_flags if flags specifies GNUTLS_TL_VERIFY_CRL
</p>
<p>This function will add the given certificate authorities
to the trusted list. 
</p>
<p><strong>Returns:</strong> The number of added elements is returned.
</p>
<p><strong>Since:</strong> 3.1
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_deinit</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_trust_list_deinit</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, unsigned int <var>all</var>)</em></dt>
<dd><p><var>list</var>: The list to be deinitialized
</p>
<p><var>all</var>: if non-zero it will deinitialize all the certificates and CRLs contained in the structure.
</p>
<p>This function will deinitialize a trust list. Note that the
 <code>all</code> flag should be typically non-zero unless you have specified
your certificates using <code>gnutls_x509_trust_list_add_cas()</code>  and you
want to prevent them from being deinitialized by this function.
</p>
<p><strong>Since:</strong> 3.0.0
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fget_005fissuer-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_get_issuer</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fget_005fissuer"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fget_005fissuer"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_get_issuer</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, gnutls_x509_crt_t <var>cert</var>, gnutls_x509_crt_t * <var>issuer</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>cert</var>: is the certificate to find issuer for
</p>
<p><var>issuer</var>: Will hold the issuer if any. Should be treated as constant.
</p>
<p><var>flags</var>: Use zero or <code>GNUTLS_TL_GET_COPY</code> 
</p>
<p>This function will find the issuer of the given certificate.
If the flag <code>GNUTLS_TL_GET_COPY</code>  is specified a copy of the issuer
will be returned which must be freed using <code>gnutls_x509_crt_deinit()</code> .
Note that the flag <code>GNUTLS_TL_GET_COPY</code>  is required for this function
to work with PKCS <code>11</code>  trust lists in a thread-safe way.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fget_005fissuer_005fby_005fdn-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_get_issuer_by_dn</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fget_005fissuer_005fby_005fdn"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fget_005fissuer_005fby_005fdn"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_get_issuer_by_dn</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const gnutls_datum_t * <var>dn</var>, gnutls_x509_crt_t * <var>issuer</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>dn</var>: is the issuer&rsquo;s DN
</p>
<p><var>issuer</var>: Will hold the issuer if any. Should be deallocated after use.
</p>
<p><var>flags</var>: Use zero
</p>
<p>This function will find the issuer with the given name, and
return a copy of the issuer, which must be freed using <code>gnutls_x509_crt_deinit()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fget_005fissuer_005fby_005fsubject_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_get_issuer_by_subject_key_id</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fget_005fissuer_005fby_005fsubject_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fget_005fissuer_005fby_005fsubject_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_get_issuer_by_subject_key_id</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const gnutls_datum_t * <var>dn</var>, const gnutls_datum_t * <var>spki</var>, gnutls_x509_crt_t * <var>issuer</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>dn</var>: is the issuer&rsquo;s DN (may be <code>NULL</code> )
</p>
<p><var>spki</var>: is the subject key ID
</p>
<p><var>issuer</var>: Will hold the issuer if any. Should be deallocated after use.
</p>
<p><var>flags</var>: Use zero
</p>
<p>This function will find the issuer with the given name and subject key ID, and
return a copy of the issuer, which must be freed using <code>gnutls_x509_crt_deinit()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005finit-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_init</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005finit"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005finit"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_init</strong> <em>(gnutls_x509_trust_list_t * <var>list</var>, unsigned int <var>size</var>)</em></dt>
<dd><p><var>list</var>: A pointer to the type to be initialized
</p>
<p><var>size</var>: The size of the internal hash table. Use (0) for default size.
</p>
<p>This function will initialize an X.509 trust list structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0.0
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fiter_005fdeinit-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_iter_deinit</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fiter_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fiter_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_x509_trust_list_iter_deinit</strong> <em>(gnutls_x509_trust_list_iter_t <var>iter</var>)</em></dt>
<dd><p><var>iter</var>: The iterator structure to be deinitialized
</p>
<p>This function will deinitialize an iterator structure.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fiter_005fget_005fca-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_iter_get_ca</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fiter_005fget_005fca"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fiter_005fget_005fca"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_iter_get_ca</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, gnutls_x509_trust_list_iter_t * <var>iter</var>, gnutls_x509_crt_t * <var>crt</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>iter</var>: A pointer to an iterator (initially the iterator should be <code>NULL</code> )
</p>
<p><var>crt</var>: where the certificate will be copied
</p>
<p>This function obtains a certificate in the trust list and advances the
iterator to the next certificate. The certificate returned in  <code>crt</code> must be
deallocated with <code>gnutls_x509_crt_deinit()</code> .
</p>
<p>When past the last element is accessed <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
is returned and the iterator is reset.
</p>
<p>After use, the iterator must be deinitialized usin
<code>gnutls_x509_trust_list_iter_deinit()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fremove_005fcas-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_remove_cas</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fremove_005fcas"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fremove_005fcas"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_remove_cas</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const gnutls_x509_crt_t * <var>clist</var>, int <var>clist_size</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>clist</var>: A list of CAs
</p>
<p><var>clist_size</var>: The length of the CA list
</p>
<p>This function will remove the given certificate authorities
from the trusted list.
</p>
<p>Note that this function can accept certificates and authorities
not yet known. In that case they will be kept in a separate
black list that will be used during certificate verification.
Unlike <code>gnutls_x509_trust_list_add_cas()</code>  there is no deinitialization
restriction for  certificate list provided in this function.
</p>
<p><strong>Returns:</strong> The number of removed elements is returned.
</p>
<p><strong>Since:</strong> 3.1.10
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fremove_005ftrust_005ffile-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_remove_trust_file</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fremove_005ftrust_005ffile"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fremove_005ftrust_005ffile"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_remove_trust_file</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const char * <var>ca_file</var>, gnutls_x509_crt_fmt_t <var>type</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>ca_file</var>: A file containing a list of CAs
</p>
<p><var>type</var>: The format of the certificates
</p>
<p>This function will remove the given certificate authorities
from the trusted list, and add them into a black list when needed. 
PKCS 11 URLs are also accepted, instead
of files, by this function.
</p>
<p>See also <code>gnutls_x509_trust_list_remove_cas()</code> .
</p>
<p><strong>Returns:</strong> The number of added elements is returned.
</p>
<p><strong>Since:</strong> 3.1.10
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fremove_005ftrust_005fmem-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_remove_trust_mem</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fremove_005ftrust_005fmem"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fremove_005ftrust_005fmem"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_remove_trust_mem</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, const gnutls_datum_t * <var>cas</var>, gnutls_x509_crt_fmt_t <var>type</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>cas</var>: A buffer containing a list of CAs (optional)
</p>
<p><var>type</var>: The format of the certificates
</p>
<p>This function will remove the provided certificate authorities
from the trusted list, and add them into a black list when needed. 
</p>
<p>See also <code>gnutls_x509_trust_list_remove_cas()</code> .
</p>
<p><strong>Returns:</strong> The number of removed elements is returned.
</p>
<p><strong>Since:</strong> 3.1.10
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_verify_crt</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt-1"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_verify_crt</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, gnutls_x509_crt_t * <var>cert_list</var>, unsigned int <var>cert_list_size</var>, unsigned int <var>flags</var>, unsigned int * <var>voutput</var>, gnutls_verify_output_function <var>func</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>cert_list</var>: is the certificate list to be verified
</p>
<p><var>cert_list_size</var>: is the certificate list size
</p>
<p><var>flags</var>: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.
</p>
<p><var>voutput</var>: will hold the certificate verification output.
</p>
<p><var>func</var>: If non-null will be called on each chain element verification with the output.
</p>
<p>This function will try to verify the given certificate and return
its status. The  <code>voutput</code> parameter will hold an OR&rsquo;ed sequence of
<code>gnutls_certificate_status_t</code>  flags.
</p>
<p>The details of the verification are the same as in <code>gnutls_x509_trust_list_verify_crt2()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt2-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_verify_crt2</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt2"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt2-1"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_verify_crt2</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, gnutls_x509_crt_t * <var>cert_list</var>, unsigned int <var>cert_list_size</var>, gnutls_typed_vdata_st * <var>data</var>, unsigned int <var>elements</var>, unsigned int <var>flags</var>, unsigned int * <var>voutput</var>, gnutls_verify_output_function <var>func</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>cert_list</var>: is the certificate list to be verified
</p>
<p><var>cert_list_size</var>: is the certificate list size
</p>
<p><var>data</var>: an array of typed data
</p>
<p><var>elements</var>: the number of data elements
</p>
<p><var>flags</var>: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.
</p>
<p><var>voutput</var>: will hold the certificate verification output.
</p>
<p><var>func</var>: If non-null will be called on each chain element verification with the output.
</p>
<p>This function will attempt to verify the given certificate and return
its status. The  <code>voutput</code> parameter will hold an OR&rsquo;ed sequence of
<code>gnutls_certificate_status_t</code>  flags. When a chain of  <code>cert_list_size</code> with 
more than one certificates is provided, the verification status will apply
to the first certificate in the chain that failed verification. The
verification process starts from the end of the chain (from CA to end
certificate).
</p>
<p>Additionally a certificate verification profile can be specified
from the ones in <code>gnutls_certificate_verification_profiles_t</code>  by
ORing the result of <code>GNUTLS_PROFILE_TO_VFLAGS()</code>  to the verification
flags.
</p>
<p>The acceptable  <code>data</code> types are <code>GNUTLS_DT_DNS_HOSTNAME</code>  and <code>GNUTLS_DT_KEY_PURPOSE_OID</code> .
The former accepts as data a null-terminated hostname, and the latter a null-terminated
object identifier (e.g., <code>GNUTLS_KP_TLS_WWW_SERVER</code> ).
If a DNS hostname is provided then this function will compare
the hostname in the certificate against the given. If names do not match the 
<code>GNUTLS_CERT_UNEXPECTED_OWNER</code>  status flag will be set. In addition it
will consider certificates provided with <code>gnutls_x509_trust_list_add_named_crt()</code> .
</p>
<p>If a key purpose OID is provided and the end-certificate contains the extended key
usage PKIX extension, it will be required to match the provided OID
or be marked for any purpose, otherwise verification will fail with 
<code>GNUTLS_CERT_PURPOSE_MISMATCH</code>  status.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. Note that verification failure will not result to an
error code, only  <code>voutput</code> will be updated.
</p>
<p><strong>Since:</strong> 3.3.8
</p></dd></dl>

<a name="gnutls_005fx509_005ftrust_005flist_005fverify_005fnamed_005fcrt-1"></a>
<h4 class="subheading">gnutls_x509_trust_list_verify_named_crt</h4>
<a name="gnutls_005fx509_005ftrust_005flist_005fverify_005fnamed_005fcrt"></a><dl>
<dt><a name="index-gnutls_005fx509_005ftrust_005flist_005fverify_005fnamed_005fcrt-1"></a>Function: <em>int</em> <strong>gnutls_x509_trust_list_verify_named_crt</strong> <em>(gnutls_x509_trust_list_t <var>list</var>, gnutls_x509_crt_t <var>cert</var>, const void * <var>name</var>, size_t <var>name_size</var>, unsigned int <var>flags</var>, unsigned int * <var>voutput</var>, gnutls_verify_output_function <var>func</var>)</em></dt>
<dd><p><var>list</var>: The list
</p>
<p><var>cert</var>: is the certificate to be verified
</p>
<p><var>name</var>: is the certificate&rsquo;s name
</p>
<p><var>name_size</var>: is the certificate&rsquo;s name size
</p>
<p><var>flags</var>: Flags that may be used to change the verification algorithm. Use OR of the gnutls_certificate_verify_flags enumerations.
</p>
<p><var>voutput</var>: will hold the certificate verification output.
</p>
<p><var>func</var>: If non-null will be called on each chain element verification with the output.
</p>
<p>This function will try to find a certificate that is associated with the provided
name &ndash;see <code>gnutls_x509_trust_list_add_named_crt()</code> . If a match is found the
certificate is considered valid. In addition to that this function will also 
check CRLs. The  <code>voutput</code> parameter will hold an OR&rsquo;ed sequence of 
<code>gnutls_certificate_status_t</code>  flags.
</p>
<p>Additionally a certificate verification profile can be specified
from the ones in <code>gnutls_certificate_verification_profiles_t</code>  by
ORing the result of <code>GNUTLS_PROFILE_TO_VFLAGS()</code>  to the verification
flags.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0.0
</p></dd></dl>


<hr>
<a name="PKCS-7-API"></a>
<div class="header">
<p>
Next: <a href="#OCSP-API" accesskey="n" rel="next">OCSP API</a>, Previous: <a href="#X509-certificate-API" accesskey="p" rel="prev">X509 certificate API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="PKCS-7-API-1"></a>
<h3 class="section">E.4 <acronym>PKCS</acronym> 7 API</h3>

<p>The following functions are to be used for PKCS 7 structures handling.
Their prototypes lie in <samp>gnutls/pkcs7.h</samp>.
</p>

<a name="gnutls_005fpkcs7_005fadd_005fattr-1"></a>
<h4 class="subheading">gnutls_pkcs7_add_attr</h4>
<a name="gnutls_005fpkcs7_005fadd_005fattr"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fadd_005fattr"></a>Function: <em>int</em> <strong>gnutls_pkcs7_add_attr</strong> <em>(gnutls_pkcs7_attrs_t * <var>list</var>, const char * <var>oid</var>, gnutls_datum_t * <var>data</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>list</var>: A list of existing attributes or pointer to <code>NULL</code>  for the first one
</p>
<p><var>oid</var>: the OID of the attribute to be set
</p>
<p><var>data</var>: the raw (DER-encoded) data of the attribute to be set
</p>
<p><var>flags</var>: zero or <code>GNUTLS_PKCS7_ATTR_ENCODE_OCTET_STRING</code> 
</p>
<p>This function will set a PKCS <code>7</code>  attribute in the provided list.
If this function fails, the previous list would be deallocated.
</p>
<p>Note that any attributes set with this function must either be
DER or BER encoded, unless a special flag is present.
</p>
<p><strong>Returns:</strong> On success, the new list head, otherwise <code>NULL</code> .
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fattrs_005fdeinit-1"></a>
<h4 class="subheading">gnutls_pkcs7_attrs_deinit</h4>
<a name="gnutls_005fpkcs7_005fattrs_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fattrs_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_pkcs7_attrs_deinit</strong> <em>(gnutls_pkcs7_attrs_t <var>list</var>)</em></dt>
<dd><p><var>list</var>: A list of existing attributes
</p>
<p>This function will clear a PKCS <code>7</code>  attribute list.
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fdeinit-1"></a>
<h4 class="subheading">gnutls_pkcs7_deinit</h4>
<a name="gnutls_005fpkcs7_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_pkcs7_deinit</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>)</em></dt>
<dd><p><var>pkcs7</var>: the type to be deinitialized
</p>
<p>This function will deinitialize a PKCS7 type.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fdelete_005fcrl-1"></a>
<h4 class="subheading">gnutls_pkcs7_delete_crl</h4>
<a name="gnutls_005fpkcs7_005fdelete_005fcrl"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fdelete_005fcrl"></a>Function: <em>int</em> <strong>gnutls_pkcs7_delete_crl</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, int <var>indx</var>)</em></dt>
<dd><p><var>pkcs7</var>: The pkcs7 type
</p>
<p><var>indx</var>: the index of the crl to delete
</p>
<p>This function will delete a crl from a PKCS7 or RFC2630 crl set.
Index starts from 0. Returns 0 on success.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fdelete_005fcrt-1"></a>
<h4 class="subheading">gnutls_pkcs7_delete_crt</h4>
<a name="gnutls_005fpkcs7_005fdelete_005fcrt"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fdelete_005fcrt"></a>Function: <em>int</em> <strong>gnutls_pkcs7_delete_crt</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, int <var>indx</var>)</em></dt>
<dd><p><var>pkcs7</var>: The pkcs7 type
</p>
<p><var>indx</var>: the index of the certificate to delete
</p>
<p>This function will delete a certificate from a PKCS7 or RFC2630
certificate set.  Index starts from 0. Returns 0 on success.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fexport-1"></a>
<h4 class="subheading">gnutls_pkcs7_export</h4>
<a name="gnutls_005fpkcs7_005fexport"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fexport"></a>Function: <em>int</em> <strong>gnutls_pkcs7_export</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_crt_fmt_t <var>format</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>pkcs7</var>: The pkcs7 type
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>output_data</var>: will contain a structure PEM or DER encoded
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will export the pkcs7 structure to DER or PEM format.
</p>
<p>If the buffer provided is not long enough to hold the output, then
* <code>output_data_size</code> is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code> 
will be returned.
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN PKCS7&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fexport2-1"></a>
<h4 class="subheading">gnutls_pkcs7_export2</h4>
<a name="gnutls_005fpkcs7_005fexport2"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fexport2"></a>Function: <em>int</em> <strong>gnutls_pkcs7_export2</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_crt_fmt_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>pkcs7</var>: The pkcs7 type
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>out</var>: will contain a structure PEM or DER encoded
</p>
<p>This function will export the pkcs7 structure to DER or PEM format.
</p>
<p>The output buffer is allocated using <code>gnutls_malloc()</code> .
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN PKCS7&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fget_005fattr-1"></a>
<h4 class="subheading">gnutls_pkcs7_get_attr</h4>
<a name="gnutls_005fpkcs7_005fget_005fattr"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fget_005fattr"></a>Function: <em>int</em> <strong>gnutls_pkcs7_get_attr</strong> <em>(gnutls_pkcs7_attrs_t <var>list</var>, unsigned <var>idx</var>, char ** <var>oid</var>, gnutls_datum_t * <var>data</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>list</var>: A list of existing attributes or <code>NULL</code>  for the first one
</p>
<p><var>idx</var>: the index of the attribute to get
</p>
<p><var>oid</var>: the OID of the attribute (read-only)
</p>
<p><var>data</var>: the raw data of the attribute
</p>
<p><var>flags</var>: zero or <code>GNUTLS_PKCS7_ATTR_ENCODE_OCTET_STRING</code> 
</p>
<p>This function will get a PKCS <code>7</code>  attribute from the provided list.
The OID is a constant string, but data will be allocated and must be
deinitialized by the caller.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned
if there are no data in the current index.
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fget_005fcrl_005fcount-1"></a>
<h4 class="subheading">gnutls_pkcs7_get_crl_count</h4>
<a name="gnutls_005fpkcs7_005fget_005fcrl_005fcount"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fget_005fcrl_005fcount"></a>Function: <em>int</em> <strong>gnutls_pkcs7_get_crl_count</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>)</em></dt>
<dd><p><var>pkcs7</var>: The pkcs7 type
</p>
<p>This function will return the number of certificates in the PKCS7
or RFC2630 crl set.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fget_005fcrl_005fraw-1"></a>
<h4 class="subheading">gnutls_pkcs7_get_crl_raw</h4>
<a name="gnutls_005fpkcs7_005fget_005fcrl_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fget_005fcrl_005fraw"></a>Function: <em>int</em> <strong>gnutls_pkcs7_get_crl_raw</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, int <var>indx</var>, void * <var>crl</var>, size_t * <var>crl_size</var>)</em></dt>
<dd><p><var>pkcs7</var>: The pkcs7 type
</p>
<p><var>indx</var>: contains the index of the crl to extract
</p>
<p><var>crl</var>: the contents of the crl will be copied there (may be null)
</p>
<p><var>crl_size</var>: should hold the size of the crl
</p>
<p>This function will return a crl of the PKCS7 or RFC2630 crl set.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.  If the provided buffer is not long enough,
then  <code>crl_size</code> is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  is
returned.  After the last crl has been read
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be returned.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fget_005fcrl_005fraw2-1"></a>
<h4 class="subheading">gnutls_pkcs7_get_crl_raw2</h4>
<a name="gnutls_005fpkcs7_005fget_005fcrl_005fraw2"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fget_005fcrl_005fraw2"></a>Function: <em>int</em> <strong>gnutls_pkcs7_get_crl_raw2</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, int <var>indx</var>, gnutls_datum_t * <var>crl</var>)</em></dt>
<dd><p><var>pkcs7</var>: The pkcs7 type
</p>
<p><var>indx</var>: contains the index of the crl to extract
</p>
<p><var>crl</var>: will contain the contents of the CRL in an allocated buffer
</p>
<p>This function will return a DER encoded CRL of the PKCS7 or RFC2630 crl set.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.  After the last crl has been read
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be returned.
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fget_005fcrt_005fcount-1"></a>
<h4 class="subheading">gnutls_pkcs7_get_crt_count</h4>
<a name="gnutls_005fpkcs7_005fget_005fcrt_005fcount"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fget_005fcrt_005fcount"></a>Function: <em>int</em> <strong>gnutls_pkcs7_get_crt_count</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>)</em></dt>
<dd><p><var>pkcs7</var>: should contain a <code>gnutls_pkcs7_t</code>  type
</p>
<p>This function will return the number of certificates in the PKCS7
or RFC2630 certificate set.
</p>
<p><strong>Returns:</strong> On success, a positive number is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fget_005fcrt_005fraw-1"></a>
<h4 class="subheading">gnutls_pkcs7_get_crt_raw</h4>
<a name="gnutls_005fpkcs7_005fget_005fcrt_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fget_005fcrt_005fraw"></a>Function: <em>int</em> <strong>gnutls_pkcs7_get_crt_raw</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, int <var>indx</var>, void * <var>certificate</var>, size_t * <var>certificate_size</var>)</em></dt>
<dd><p><var>pkcs7</var>: should contain a gnutls_pkcs7_t type
</p>
<p><var>indx</var>: contains the index of the certificate to extract
</p>
<p><var>certificate</var>: the contents of the certificate will be copied
there (may be null)
</p>
<p><var>certificate_size</var>: should hold the size of the certificate
</p>
<p>This function will return a certificate of the PKCS7 or RFC2630
certificate set.
</p>
<p>After the last certificate has been read
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.  If the provided buffer is not long enough,
then  <code>certificate_size</code> is updated and
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  is returned.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fget_005fcrt_005fraw2-1"></a>
<h4 class="subheading">gnutls_pkcs7_get_crt_raw2</h4>
<a name="gnutls_005fpkcs7_005fget_005fcrt_005fraw2"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fget_005fcrt_005fraw2"></a>Function: <em>int</em> <strong>gnutls_pkcs7_get_crt_raw2</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, int <var>indx</var>, gnutls_datum_t * <var>cert</var>)</em></dt>
<dd><p><var>pkcs7</var>: should contain a gnutls_pkcs7_t type
</p>
<p><var>indx</var>: contains the index of the certificate to extract
</p>
<p><var>cert</var>: will hold the contents of the certificate; must be deallocated with <code>gnutls_free()</code> 
</p>
<p>This function will return a certificate of the PKCS7 or RFC2630
certificate set.
</p>
<p>After the last certificate has been read
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.  If the provided buffer is not long enough,
then  <code>certificate_size</code> is updated and
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  is returned.
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fget_005fembedded_005fdata-1"></a>
<h4 class="subheading">gnutls_pkcs7_get_embedded_data</h4>
<a name="gnutls_005fpkcs7_005fget_005fembedded_005fdata"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fget_005fembedded_005fdata"></a>Function: <em>int</em> <strong>gnutls_pkcs7_get_embedded_data</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, unsigned <var>idx</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>pkcs7</var>: should contain a gnutls_pkcs7_t type
</p>
<p><var>idx</var>: the index of the signature info to get the data from
</p>
<p><var>data</var>: will hold the embedded data in the provided structure
</p>
<p>This function will return the data embedded in the signature of
the PKCS7 structure. If no data are available then
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be returned.
</p>
<p>Note, that since a PKCS<code>7</code>  structure may contain embedded data
for each attached signature, this function accepts and index which
corresponds to the signature index to get the data from.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. 
</p>
<p><strong>Since:</strong> 3.4.8
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fget_005fsignature_005fcount-1"></a>
<h4 class="subheading">gnutls_pkcs7_get_signature_count</h4>
<a name="gnutls_005fpkcs7_005fget_005fsignature_005fcount"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fget_005fsignature_005fcount"></a>Function: <em>int</em> <strong>gnutls_pkcs7_get_signature_count</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>)</em></dt>
<dd><p><var>pkcs7</var>: should contain a <code>gnutls_pkcs7_t</code>  type
</p>
<p>This function will return the number of signatures in the PKCS7
structure.
</p>
<p><strong>Returns:</strong> On success, a positive number is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.3
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fget_005fsignature_005finfo-1"></a>
<h4 class="subheading">gnutls_pkcs7_get_signature_info</h4>
<a name="gnutls_005fpkcs7_005fget_005fsignature_005finfo"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fget_005fsignature_005finfo"></a>Function: <em>int</em> <strong>gnutls_pkcs7_get_signature_info</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, unsigned <var>idx</var>, gnutls_pkcs7_signature_info_st * <var>info</var>)</em></dt>
<dd><p><var>pkcs7</var>: should contain a <code>gnutls_pkcs7_t</code>  type
</p>
<p><var>idx</var>: the index of the signature info to check
</p>
<p><var>info</var>: will contain the output signature
</p>
<p>This function will return information about the signature identified
by idx in the provided PKCS <code>7</code>  structure. The information should be
deinitialized using <code>gnutls_pkcs7_signature_info_deinit()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fimport-1"></a>
<h4 class="subheading">gnutls_pkcs7_import</h4>
<a name="gnutls_005fpkcs7_005fimport"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fimport"></a>Function: <em>int</em> <strong>gnutls_pkcs7_import</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>pkcs7</var>: The data to store the parsed PKCS7.
</p>
<p><var>data</var>: The DER or PEM encoded PKCS7.
</p>
<p><var>format</var>: One of DER or PEM
</p>
<p>This function will convert the given DER or PEM encoded PKCS7 to
the native <code>gnutls_pkcs7_t</code>  format.  The output will be stored in
 <code>pkcs7</code> .
</p>
<p>If the PKCS7 is PEM encoded it should have a header of &quot;PKCS7&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005finit-1"></a>
<h4 class="subheading">gnutls_pkcs7_init</h4>
<a name="gnutls_005fpkcs7_005finit"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005finit"></a>Function: <em>int</em> <strong>gnutls_pkcs7_init</strong> <em>(gnutls_pkcs7_t * <var>pkcs7</var>)</em></dt>
<dd><p><var>pkcs7</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize a PKCS7 structure. PKCS7 structures
usually contain lists of X.509 Certificates and X.509 Certificate
revocation lists.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fprint-1"></a>
<h4 class="subheading">gnutls_pkcs7_print</h4>
<a name="gnutls_005fpkcs7_005fprint"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fprint"></a>Function: <em>int</em> <strong>gnutls_pkcs7_print</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, gnutls_certificate_print_formats_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>pkcs7</var>: The PKCS7 struct to be printed
</p>
<p><var>format</var>: Indicate the format to use
</p>
<p><var>out</var>: Newly allocated datum with null terminated string.
</p>
<p>This function will pretty print a signed PKCS <code>7</code>  structure, suitable for
display to a human.
</p>
<p>Currently the supported formats are <code>GNUTLS_CRT_PRINT_FULL</code>  and
<code>GNUTLS_CRT_PRINT_COMPACT</code> .
</p>
<p>The output  <code>out</code> needs to be deallocated using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fset_005fcrl-1"></a>
<h4 class="subheading">gnutls_pkcs7_set_crl</h4>
<a name="gnutls_005fpkcs7_005fset_005fcrl"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fset_005fcrl"></a>Function: <em>int</em> <strong>gnutls_pkcs7_set_crl</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_crl_t <var>crl</var>)</em></dt>
<dd><p><var>pkcs7</var>: The pkcs7 type
</p>
<p><var>crl</var>: the DER encoded crl to be added
</p>
<p>This function will add a parsed CRL to the PKCS7 or RFC2630 crl
set.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fset_005fcrl_005fraw-1"></a>
<h4 class="subheading">gnutls_pkcs7_set_crl_raw</h4>
<a name="gnutls_005fpkcs7_005fset_005fcrl_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fset_005fcrl_005fraw"></a>Function: <em>int</em> <strong>gnutls_pkcs7_set_crl_raw</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, const gnutls_datum_t * <var>crl</var>)</em></dt>
<dd><p><var>pkcs7</var>: The pkcs7 type
</p>
<p><var>crl</var>: the DER encoded crl to be added
</p>
<p>This function will add a crl to the PKCS7 or RFC2630 crl set.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fset_005fcrt-1"></a>
<h4 class="subheading">gnutls_pkcs7_set_crt</h4>
<a name="gnutls_005fpkcs7_005fset_005fcrt"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fset_005fcrt"></a>Function: <em>int</em> <strong>gnutls_pkcs7_set_crt</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_crt_t <var>crt</var>)</em></dt>
<dd><p><var>pkcs7</var>: The pkcs7 type
</p>
<p><var>crt</var>: the certificate to be copied.
</p>
<p>This function will add a parsed certificate to the PKCS7 or
RFC2630 certificate set.  This is a wrapper function over
<code>gnutls_pkcs7_set_crt_raw()</code>  .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fset_005fcrt_005fraw-1"></a>
<h4 class="subheading">gnutls_pkcs7_set_crt_raw</h4>
<a name="gnutls_005fpkcs7_005fset_005fcrt_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fset_005fcrt_005fraw"></a>Function: <em>int</em> <strong>gnutls_pkcs7_set_crt_raw</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, const gnutls_datum_t * <var>crt</var>)</em></dt>
<dd><p><var>pkcs7</var>: The pkcs7 type
</p>
<p><var>crt</var>: the DER encoded certificate to be added
</p>
<p>This function will add a certificate to the PKCS7 or RFC2630
certificate set.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fsign-1"></a>
<h4 class="subheading">gnutls_pkcs7_sign</h4>
<a name="gnutls_005fpkcs7_005fsign"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fsign-1"></a>Function: <em>int</em> <strong>gnutls_pkcs7_sign</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_crt_t <var>signer</var>, gnutls_privkey_t <var>signer_key</var>, const gnutls_datum_t * <var>data</var>, gnutls_pkcs7_attrs_t <var>signed_attrs</var>, gnutls_pkcs7_attrs_t <var>unsigned_attrs</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>pkcs7</var>: should contain a <code>gnutls_pkcs7_t</code>  type
</p>
<p><var>signer</var>: the certificate to sign the structure
</p>
<p><var>signer_key</var>: the key to sign the structure
</p>
<p><var>data</var>: The data to be signed or <code>NULL</code>  if the data are already embedded
</p>
<p><var>signed_attrs</var>: Any additional attributes to be included in the signed ones (or <code>NULL</code> )
</p>
<p><var>unsigned_attrs</var>: Any additional attributes to be included in the unsigned ones (or <code>NULL</code> )
</p>
<p><var>dig</var>: The digest algorithm to use for signing
</p>
<p><var>flags</var>: Should be zero or one of <code>GNUTLS_PKCS7</code>  flags
</p>
<p>This function will add a signature in the provided PKCS <code>7</code>  structure
for the provided data. Multiple signatures can be made with different
signers.
</p>
<p>The available flags are:
<code>GNUTLS_PKCS7_EMBED_DATA</code> , <code>GNUTLS_PKCS7_INCLUDE_TIME</code> , <code>GNUTLS_PKCS7_INCLUDE_CERT</code> ,
and <code>GNUTLS_PKCS7_WRITE_SPKI</code> . They are explained in the <code>gnutls_pkcs7_sign_flags</code> 
definition.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. 
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fsignature_005finfo_005fdeinit-1"></a>
<h4 class="subheading">gnutls_pkcs7_signature_info_deinit</h4>
<a name="gnutls_005fpkcs7_005fsignature_005finfo_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fsignature_005finfo_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_pkcs7_signature_info_deinit</strong> <em>(gnutls_pkcs7_signature_info_st * <var>info</var>)</em></dt>
<dd><p><var>info</var>: should point to a <code>gnutls_pkcs7_signature_info_st</code>  structure
</p>
<p>This function will deinitialize any allocated value in the
provided <code>gnutls_pkcs7_signature_info_st</code> .
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fverify-1"></a>
<h4 class="subheading">gnutls_pkcs7_verify</h4>
<a name="gnutls_005fpkcs7_005fverify"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fverify"></a>Function: <em>int</em> <strong>gnutls_pkcs7_verify</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_trust_list_t <var>tl</var>, gnutls_typed_vdata_st * <var>vdata</var>, unsigned int <var>vdata_size</var>, unsigned <var>idx</var>, const gnutls_datum_t * <var>data</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>pkcs7</var>: should contain a <code>gnutls_pkcs7_t</code>  type
</p>
<p><var>tl</var>: A list of trusted certificates
</p>
<p><var>vdata</var>: an array of typed data
</p>
<p><var>vdata_size</var>: the number of data elements
</p>
<p><var>idx</var>: the index of the signature info to check
</p>
<p><var>data</var>: The data to be verified or <code>NULL</code> 
</p>
<p><var>flags</var>: Zero or an OR list of <code>gnutls_certificate_verify_flags</code> 
</p>
<p>This function will verify the provided data against the signature
present in the SignedData of the PKCS <code>7</code>  structure. If the data
provided are NULL then the data in the encapsulatedContent field
will be used instead.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. A verification error results to a
<code>GNUTLS_E_PK_SIG_VERIFY_FAILED</code>  and the lack of encapsulated data
to verify to a <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> .
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<a name="gnutls_005fpkcs7_005fverify_005fdirect-1"></a>
<h4 class="subheading">gnutls_pkcs7_verify_direct</h4>
<a name="gnutls_005fpkcs7_005fverify_005fdirect"></a><dl>
<dt><a name="index-gnutls_005fpkcs7_005fverify_005fdirect"></a>Function: <em>int</em> <strong>gnutls_pkcs7_verify_direct</strong> <em>(gnutls_pkcs7_t <var>pkcs7</var>, gnutls_x509_crt_t <var>signer</var>, unsigned <var>idx</var>, const gnutls_datum_t * <var>data</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>pkcs7</var>: should contain a <code>gnutls_pkcs7_t</code>  type
</p>
<p><var>signer</var>: the certificate believed to have signed the structure
</p>
<p><var>idx</var>: the index of the signature info to check
</p>
<p><var>data</var>: The data to be verified or <code>NULL</code> 
</p>
<p><var>flags</var>: Zero or an OR list of <code>gnutls_certificate_verify_flags</code> 
</p>
<p>This function will verify the provided data against the signature
present in the SignedData of the PKCS <code>7</code>  structure. If the data
provided are NULL then the data in the encapsulatedContent field
will be used instead.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. A verification error results to a
<code>GNUTLS_E_PK_SIG_VERIFY_FAILED</code>  and the lack of encapsulated data
to verify to a <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> .
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>


<hr>
<a name="OCSP-API"></a>
<div class="header">
<p>
Next: <a href="#OpenPGP-API" accesskey="n" rel="next">OpenPGP API</a>, Previous: <a href="#PKCS-7-API" accesskey="p" rel="prev">PKCS 7 API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OCSP-API-1"></a>
<h3 class="section">E.5 <acronym>OCSP</acronym> API</h3>
<a name="index-OCSP-Functions"></a>

<p>The following functions are for <acronym>OCSP</acronym> certificate status
checking.  Their prototypes lie in <samp>gnutls/ocsp.h</samp>.
</p>

<a name="gnutls_005focsp_005freq_005fadd_005fcert-1"></a>
<h4 class="subheading">gnutls_ocsp_req_add_cert</h4>
<a name="gnutls_005focsp_005freq_005fadd_005fcert"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005fadd_005fcert"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_add_cert</strong> <em>(gnutls_ocsp_req_t <var>req</var>, gnutls_digest_algorithm_t <var>digest</var>, gnutls_x509_crt_t <var>issuer</var>, gnutls_x509_crt_t <var>cert</var>)</em></dt>
<dd><p><var>req</var>: should contain a <code>gnutls_ocsp_req_t</code>  type
</p>
<p><var>digest</var>: hash algorithm, a <code>gnutls_digest_algorithm_t</code>  value
</p>
<p><var>issuer</var>: issuer of  <code>subject</code> certificate
</p>
<p><var>cert</var>: certificate to request status for
</p>
<p>This function will add another request to the OCSP request for a
particular certificate.  The issuer name hash, issuer key hash, and
serial number fields is populated as follows.  The issuer name and
the serial number is taken from  <code>cert</code> .  The issuer key is taken
from  <code>issuer</code> .  The hashed values will be hashed using the  <code>digest</code> algorithm, normally <code>GNUTLS_DIG_SHA1</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005fadd_005fcert_005fid-1"></a>
<h4 class="subheading">gnutls_ocsp_req_add_cert_id</h4>
<a name="gnutls_005focsp_005freq_005fadd_005fcert_005fid"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005fadd_005fcert_005fid"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_add_cert_id</strong> <em>(gnutls_ocsp_req_t <var>req</var>, gnutls_digest_algorithm_t <var>digest</var>, const gnutls_datum_t * <var>issuer_name_hash</var>, const gnutls_datum_t * <var>issuer_key_hash</var>, const gnutls_datum_t * <var>serial_number</var>)</em></dt>
<dd><p><var>req</var>: should contain a <code>gnutls_ocsp_req_t</code>  type
</p>
<p><var>digest</var>: hash algorithm, a <code>gnutls_digest_algorithm_t</code>  value
</p>
<p><var>issuer_name_hash</var>: hash of issuer&rsquo;s DN
</p>
<p><var>issuer_key_hash</var>: hash of issuer&rsquo;s public key
</p>
<p><var>serial_number</var>: serial number of certificate to check
</p>
<p>This function will add another request to the OCSP request for a
particular certificate having the issuer name hash of
 <code>issuer_name_hash</code> and issuer key hash of  <code>issuer_key_hash</code> (both
hashed using  <code>digest</code> ) and serial number  <code>serial_number</code> .
</p>
<p>The information needed corresponds to the CertID structure:
</p>
<p>&lt;informalexample&gt;&lt;programlisting&gt;
CertID          ::=     SEQUENCE {
hashAlgorithm       AlgorithmIdentifier,
issuerNameHash      OCTET STRING, &ndash; Hash of Issuer&rsquo;s DN
issuerKeyHash       OCTET STRING, &ndash; Hash of Issuers public key
serialNumber        CertificateSerialNumber }
&lt;/programlisting&gt;&lt;/informalexample&gt;
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005fdeinit-1"></a>
<h4 class="subheading">gnutls_ocsp_req_deinit</h4>
<a name="gnutls_005focsp_005freq_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_ocsp_req_deinit</strong> <em>(gnutls_ocsp_req_t <var>req</var>)</em></dt>
<dd><p><var>req</var>: The data to be deinitialized
</p>
<p>This function will deinitialize a OCSP request structure.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005fexport-1"></a>
<h4 class="subheading">gnutls_ocsp_req_export</h4>
<a name="gnutls_005focsp_005freq_005fexport"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005fexport"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_export</strong> <em>(gnutls_ocsp_req_t <var>req</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>req</var>: Holds the OCSP request
</p>
<p><var>data</var>: newly allocate buffer holding DER encoded OCSP request
</p>
<p>This function will export the OCSP request to DER format.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005fget_005fcert_005fid-1"></a>
<h4 class="subheading">gnutls_ocsp_req_get_cert_id</h4>
<a name="gnutls_005focsp_005freq_005fget_005fcert_005fid"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005fget_005fcert_005fid"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_get_cert_id</strong> <em>(gnutls_ocsp_req_t <var>req</var>, unsigned <var>indx</var>, gnutls_digest_algorithm_t * <var>digest</var>, gnutls_datum_t * <var>issuer_name_hash</var>, gnutls_datum_t * <var>issuer_key_hash</var>, gnutls_datum_t * <var>serial_number</var>)</em></dt>
<dd><p><var>req</var>: should contain a <code>gnutls_ocsp_req_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension OID to get. Use (0) to get the first one.
</p>
<p><var>digest</var>: output variable with <code>gnutls_digest_algorithm_t</code>  hash algorithm
</p>
<p><var>issuer_name_hash</var>: output buffer with hash of issuer&rsquo;s DN
</p>
<p><var>issuer_key_hash</var>: output buffer with hash of issuer&rsquo;s public key
</p>
<p><var>serial_number</var>: output buffer with serial number of certificate to check
</p>
<p>This function will return the certificate information of the
 <code>indx</code> &rsquo;ed request in the OCSP request.  The information returned
corresponds to the CertID structure:
</p>
<p>&lt;informalexample&gt;&lt;programlisting&gt;
CertID          ::=     SEQUENCE {
hashAlgorithm       AlgorithmIdentifier,
issuerNameHash      OCTET STRING, &ndash; Hash of Issuer&rsquo;s DN
issuerKeyHash       OCTET STRING, &ndash; Hash of Issuers public key
serialNumber        CertificateSerialNumber }
&lt;/programlisting&gt;&lt;/informalexample&gt;
</p>
<p>Each of the pointers to output variables may be NULL to indicate
that the caller is not interested in that value.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.  If you have reached the last
CertID available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be
returned.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005fget_005fextension-1"></a>
<h4 class="subheading">gnutls_ocsp_req_get_extension</h4>
<a name="gnutls_005focsp_005freq_005fget_005fextension"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005fget_005fextension"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_get_extension</strong> <em>(gnutls_ocsp_req_t <var>req</var>, unsigned <var>indx</var>, gnutls_datum_t * <var>oid</var>, unsigned int * <var>critical</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>req</var>: should contain a <code>gnutls_ocsp_req_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension OID to get. Use (0) to get the first one.
</p>
<p><var>oid</var>: will hold newly allocated buffer with OID of extension, may be NULL
</p>
<p><var>critical</var>: output variable with critical flag, may be NULL.
</p>
<p><var>data</var>: will hold newly allocated buffer with extension data, may be NULL
</p>
<p>This function will return all information about the requested
extension in the OCSP request.  The information returned is the
OID, the critical flag, and the data itself.  The extension OID
will be stored as a string.  Any of  <code>oid</code> ,  <code>critical</code> , and  <code>data</code> may
be NULL which means that the caller is not interested in getting
that information back.
</p>
<p>The caller needs to deallocate memory by calling <code>gnutls_free()</code>  on
 <code>oid</code> -&gt;data and  <code>data</code> -&gt;data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.  If you have reached the last
extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will
be returned.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005fget_005fnonce-1"></a>
<h4 class="subheading">gnutls_ocsp_req_get_nonce</h4>
<a name="gnutls_005focsp_005freq_005fget_005fnonce"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005fget_005fnonce"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_get_nonce</strong> <em>(gnutls_ocsp_req_t <var>req</var>, unsigned int * <var>critical</var>, gnutls_datum_t * <var>nonce</var>)</em></dt>
<dd><p><var>req</var>: should contain a <code>gnutls_ocsp_req_t</code>  type
</p>
<p><var>critical</var>: whether nonce extension is marked critical, or NULL
</p>
<p><var>nonce</var>: will hold newly allocated buffer with nonce data
</p>
<p>This function will return the OCSP request nonce extension data.
</p>
<p>The caller needs to deallocate memory by calling <code>gnutls_free()</code>  on
 <code>nonce</code> -&gt;data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005fget_005fversion-1"></a>
<h4 class="subheading">gnutls_ocsp_req_get_version</h4>
<a name="gnutls_005focsp_005freq_005fget_005fversion"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005fget_005fversion"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_get_version</strong> <em>(gnutls_ocsp_req_t <var>req</var>)</em></dt>
<dd><p><var>req</var>: should contain a <code>gnutls_ocsp_req_t</code>  type
</p>
<p>This function will return the version of the OCSP request.
Typically this is always 1 indicating version 1.
</p>
<p><strong>Returns:</strong> version of OCSP request, or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005fimport-1"></a>
<h4 class="subheading">gnutls_ocsp_req_import</h4>
<a name="gnutls_005focsp_005freq_005fimport"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005fimport"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_import</strong> <em>(gnutls_ocsp_req_t <var>req</var>, const gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>req</var>: The data to store the parsed request.
</p>
<p><var>data</var>: DER encoded OCSP request.
</p>
<p>This function will convert the given DER encoded OCSP request to
the native <code>gnutls_ocsp_req_t</code>  format. The output will be stored in
 <code>req</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005finit-1"></a>
<h4 class="subheading">gnutls_ocsp_req_init</h4>
<a name="gnutls_005focsp_005freq_005finit"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005finit"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_init</strong> <em>(gnutls_ocsp_req_t * <var>req</var>)</em></dt>
<dd><p><var>req</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize an OCSP request structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005fprint-1"></a>
<h4 class="subheading">gnutls_ocsp_req_print</h4>
<a name="gnutls_005focsp_005freq_005fprint"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005fprint"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_print</strong> <em>(gnutls_ocsp_req_t <var>req</var>, gnutls_ocsp_print_formats_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>req</var>: The data to be printed
</p>
<p><var>format</var>: Indicate the format to use
</p>
<p><var>out</var>: Newly allocated datum with (0) terminated string.
</p>
<p>This function will pretty print a OCSP request, suitable for
display to a human.
</p>
<p>If the format is <code>GNUTLS_OCSP_PRINT_FULL</code>  then all fields of the
request will be output, on multiple lines.
</p>
<p>The output  <code>out</code> -&gt;data needs to be deallocate using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005frandomize_005fnonce-1"></a>
<h4 class="subheading">gnutls_ocsp_req_randomize_nonce</h4>
<a name="gnutls_005focsp_005freq_005frandomize_005fnonce"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005frandomize_005fnonce"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_randomize_nonce</strong> <em>(gnutls_ocsp_req_t <var>req</var>)</em></dt>
<dd><p><var>req</var>: should contain a <code>gnutls_ocsp_req_t</code>  type
</p>
<p>This function will add or update an nonce extension to the OCSP
request with a newly generated random value.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005fset_005fextension-1"></a>
<h4 class="subheading">gnutls_ocsp_req_set_extension</h4>
<a name="gnutls_005focsp_005freq_005fset_005fextension"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005fset_005fextension"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_set_extension</strong> <em>(gnutls_ocsp_req_t <var>req</var>, const char * <var>oid</var>, unsigned int <var>critical</var>, const gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>req</var>: should contain a <code>gnutls_ocsp_req_t</code>  type
</p>
<p><var>oid</var>: buffer with OID of extension as a string.
</p>
<p><var>critical</var>: critical flag, normally false.
</p>
<p><var>data</var>: the extension data
</p>
<p>This function will add an extension to the OCSP request.  Calling
this function multiple times for the same OID will overwrite values
from earlier calls.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.
</p></dd></dl>

<a name="gnutls_005focsp_005freq_005fset_005fnonce-1"></a>
<h4 class="subheading">gnutls_ocsp_req_set_nonce</h4>
<a name="gnutls_005focsp_005freq_005fset_005fnonce"></a><dl>
<dt><a name="index-gnutls_005focsp_005freq_005fset_005fnonce"></a>Function: <em>int</em> <strong>gnutls_ocsp_req_set_nonce</strong> <em>(gnutls_ocsp_req_t <var>req</var>, unsigned int <var>critical</var>, const gnutls_datum_t * <var>nonce</var>)</em></dt>
<dd><p><var>req</var>: should contain a <code>gnutls_ocsp_req_t</code>  type
</p>
<p><var>critical</var>: critical flag, normally false.
</p>
<p><var>nonce</var>: the nonce data
</p>
<p>This function will add an nonce extension to the OCSP request.
Calling this function multiple times will overwrite values from
earlier calls.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fcheck_005fcrt-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_check_crt</h4>
<a name="gnutls_005focsp_005fresp_005fcheck_005fcrt"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fcheck_005fcrt"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_check_crt</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, unsigned int <var>indx</var>, gnutls_x509_crt_t <var>crt</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p><var>indx</var>: Specifies response number to get. Use (0) to get the first one.
</p>
<p><var>crt</var>: The certificate to check
</p>
<p>This function will check whether the OCSP response
is about the provided certificate.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.  
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fdeinit-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_deinit</h4>
<a name="gnutls_005focsp_005fresp_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_ocsp_resp_deinit</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>)</em></dt>
<dd><p><var>resp</var>: The data to be deinitialized
</p>
<p>This function will deinitialize a OCSP response structure.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fexport-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_export</h4>
<a name="gnutls_005focsp_005fresp_005fexport"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fexport"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_export</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>resp</var>: Holds the OCSP response
</p>
<p><var>data</var>: newly allocate buffer holding DER encoded OCSP response
</p>
<p>This function will export the OCSP response to DER format.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fget_005fcerts-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_get_certs</h4>
<a name="gnutls_005focsp_005fresp_005fget_005fcerts"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fcerts"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_get_certs</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, gnutls_x509_crt_t ** <var>certs</var>, size_t * <var>ncerts</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p><var>certs</var>: newly allocated array with <code>gnutls_x509_crt_t</code>  certificates
</p>
<p><var>ncerts</var>: output variable with number of allocated certs.
</p>
<p>This function will extract the X.509 certificates found in the
Basic OCSP Response.  The  <code>certs</code> output variable will hold a newly
allocated zero-terminated array with X.509 certificates.
</p>
<p>Every certificate in the array needs to be de-allocated with
<code>gnutls_x509_crt_deinit()</code>  and the array itself must be freed using
<code>gnutls_free()</code> .
</p>
<p>Both the  <code>certs</code> and  <code>ncerts</code> variables may be NULL.  Then the
function will work as normal but will not return the NULL:d
information.  This can be used to get the number of certificates
only, or to just get the certificate array without its size.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fget_005fextension-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_get_extension</h4>
<a name="gnutls_005focsp_005fresp_005fget_005fextension"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fextension"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_get_extension</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, unsigned <var>indx</var>, gnutls_datum_t * <var>oid</var>, unsigned int * <var>critical</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p><var>indx</var>: Specifies which extension OID to get. Use (0) to get the first one.
</p>
<p><var>oid</var>: will hold newly allocated buffer with OID of extension, may be NULL
</p>
<p><var>critical</var>: output variable with critical flag, may be NULL.
</p>
<p><var>data</var>: will hold newly allocated buffer with extension data, may be NULL
</p>
<p>This function will return all information about the requested
extension in the OCSP response.  The information returned is the
OID, the critical flag, and the data itself.  The extension OID
will be stored as a string.  Any of  <code>oid</code> ,  <code>critical</code> , and  <code>data</code> may
be NULL which means that the caller is not interested in getting
that information back.
</p>
<p>The caller needs to deallocate memory by calling <code>gnutls_free()</code>  on
 <code>oid</code> -&gt;data and  <code>data</code> -&gt;data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.  If you have reached the last
extension available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will
be returned.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fget_005fnonce-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_get_nonce</h4>
<a name="gnutls_005focsp_005fresp_005fget_005fnonce"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fnonce"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_get_nonce</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, unsigned int * <var>critical</var>, gnutls_datum_t * <var>nonce</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p><var>critical</var>: whether nonce extension is marked critical
</p>
<p><var>nonce</var>: will hold newly allocated buffer with nonce data
</p>
<p>This function will return the Basic OCSP Response nonce extension
data.
</p>
<p>The caller needs to deallocate memory by calling <code>gnutls_free()</code>  on
 <code>nonce</code> -&gt;data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fget_005fproduced-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_get_produced</h4>
<a name="gnutls_005focsp_005fresp_005fget_005fproduced"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fproduced"></a>Function: <em>time_t</em> <strong>gnutls_ocsp_resp_get_produced</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p>This function will return the time when the OCSP response was
signed.
</p>
<p><strong>Returns:</strong> signing time, or (time_t)-1 on error.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fget_005fresponder-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_get_responder</h4>
<a name="gnutls_005focsp_005fresp_005fget_005fresponder"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fresponder"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_get_responder</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, gnutls_datum_t * <var>dn</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p><var>dn</var>: newly allocated buffer with name
</p>
<p>This function will extract the name of the Basic OCSP Response in
the provided buffer. The name will be in the form
&quot;C=xxxx,O=yyyy,CN=zzzz&quot; as described in RFC2253. The output string
will be ASCII or UTF-8 encoded, depending on the certificate data.
</p>
<p>If the responder ID is not a name but a hash, this function
will return zero and the  <code>dn</code> elements will be set to <code>NULL</code> .
</p>
<p>The caller needs to deallocate memory by calling <code>gnutls_free()</code>  on
 <code>dn</code> -&gt;data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fget_005fresponder_005fraw_005fid-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_get_responder_raw_id</h4>
<a name="gnutls_005focsp_005fresp_005fget_005fresponder_005fraw_005fid"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fresponder_005fraw_005fid"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_get_responder_raw_id</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, unsigned <var>type</var>, gnutls_datum_t * <var>raw</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p><var>type</var>: should be <code>GNUTLS_OCSP_RESP_ID_KEY</code>  or <code>GNUTLS_OCSP_RESP_ID_DN</code> 
</p>
<p><var>raw</var>: newly allocated buffer with the raw ID
</p>
<p>This function will extract the raw key (or DN) ID of the Basic OCSP Response in
the provided buffer. If the responder ID is not a key ID then
this function will return <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> .
</p>
<p>The caller needs to deallocate memory by calling <code>gnutls_free()</code>  on
 <code>dn</code> -&gt;data.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fget_005fresponse-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_get_response</h4>
<a name="gnutls_005focsp_005fresp_005fget_005fresponse"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fresponse"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_get_response</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, gnutls_datum_t * <var>response_type_oid</var>, gnutls_datum_t * <var>response</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p><var>response_type_oid</var>: newly allocated output buffer with response type OID
</p>
<p><var>response</var>: newly allocated output buffer with DER encoded response
</p>
<p>This function will extract the response type OID in and the
response data from an OCSP response.  Normally the
 <code>response_type_oid</code> is always &quot;1.3.6.1.5.5.7.48.1.1&quot; which means the
 <code>response</code> should be decoded as a Basic OCSP Response, but
technically other response types could be used.
</p>
<p>This function is typically only useful when you want to extract the
response type OID of an response for diagnostic purposes.
Otherwise <code>gnutls_ocsp_resp_import()</code>  will decode the basic OCSP
response part and the caller need not worry about that aspect.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fget_005fsignature-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_get_signature</h4>
<a name="gnutls_005focsp_005fresp_005fget_005fsignature"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fsignature"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_get_signature</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, gnutls_datum_t * <var>sig</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p><var>sig</var>: newly allocated output buffer with signature data
</p>
<p>This function will extract the signature field of a OCSP response.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fget_005fsignature_005falgorithm-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_get_signature_algorithm</h4>
<a name="gnutls_005focsp_005fresp_005fget_005fsignature_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fsignature_005falgorithm"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_get_signature_algorithm</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p>This function will return a value of the <code>gnutls_sign_algorithm_t</code> 
enumeration that is the signature algorithm that has been used to
sign the OCSP response.
</p>
<p><strong>Returns:</strong> a <code>gnutls_sign_algorithm_t</code>  value, or a negative error code
on error.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fget_005fsingle-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_get_single</h4>
<a name="gnutls_005focsp_005fresp_005fget_005fsingle"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fsingle-1"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_get_single</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, unsigned <var>indx</var>, gnutls_digest_algorithm_t * <var>digest</var>, gnutls_datum_t * <var>issuer_name_hash</var>, gnutls_datum_t * <var>issuer_key_hash</var>, gnutls_datum_t * <var>serial_number</var>, unsigned int * <var>cert_status</var>, time_t * <var>this_update</var>, time_t * <var>next_update</var>, time_t * <var>revocation_time</var>, unsigned int * <var>revocation_reason</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p><var>indx</var>: Specifies response number to get. Use (0) to get the first one.
</p>
<p><var>digest</var>: output variable with <code>gnutls_digest_algorithm_t</code>  hash algorithm
</p>
<p><var>issuer_name_hash</var>: output buffer with hash of issuer&rsquo;s DN
</p>
<p><var>issuer_key_hash</var>: output buffer with hash of issuer&rsquo;s public key
</p>
<p><var>serial_number</var>: output buffer with serial number of certificate to check
</p>
<p><var>cert_status</var>: a certificate status, a <code>gnutls_ocsp_cert_status_t</code>  enum.
</p>
<p><var>this_update</var>: time at which the status is known to be correct.
</p>
<p><var>next_update</var>: when newer information will be available, or (time_t)-1 if unspecified
</p>
<p><var>revocation_time</var>: when  <code>cert_status</code> is <code>GNUTLS_OCSP_CERT_REVOKED</code> , holds time of revocation.
</p>
<p><var>revocation_reason</var>: revocation reason, a <code>gnutls_x509_crl_reason_t</code>  enum.
</p>
<p>This function will return the certificate information of the
 <code>indx</code> &rsquo;ed response in the Basic OCSP Response  <code>resp</code> .  The
information returned corresponds to the OCSP SingleResponse structure
except the final singleExtensions.
</p>
<p>Each of the pointers to output variables may be NULL to indicate
that the caller is not interested in that value.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error code is returned.  If you have reached the last
CertID available <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be
returned.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fget_005fstatus-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_get_status</h4>
<a name="gnutls_005focsp_005fresp_005fget_005fstatus"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fstatus"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_get_status</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p>This function will return the status of a OCSP response, an
<code>gnutls_ocsp_resp_status_t</code>  enumeration.
</p>
<p><strong>Returns:</strong> status of OCSP request as a <code>gnutls_ocsp_resp_status_t</code> , or
a negative error code on error.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fget_005fversion-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_get_version</h4>
<a name="gnutls_005focsp_005fresp_005fget_005fversion"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fget_005fversion"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_get_version</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p>This function will return the version of the Basic OCSP Response.
Typically this is always 1 indicating version 1.
</p>
<p><strong>Returns:</strong> version of Basic OCSP response, or a negative error code
on error.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fimport-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_import</h4>
<a name="gnutls_005focsp_005fresp_005fimport"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fimport"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_import</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, const gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>resp</var>: The data to store the parsed response.
</p>
<p><var>data</var>: DER encoded OCSP response.
</p>
<p>This function will convert the given DER encoded OCSP response to
the native <code>gnutls_ocsp_resp_t</code>  format.  It also decodes the Basic
OCSP Response part, if any.  The output will be stored in  <code>resp</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005finit-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_init</h4>
<a name="gnutls_005focsp_005fresp_005finit"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005finit"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_init</strong> <em>(gnutls_ocsp_resp_t * <var>resp</var>)</em></dt>
<dd><p><var>resp</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize an OCSP response structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fprint-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_print</h4>
<a name="gnutls_005focsp_005fresp_005fprint"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fprint"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_print</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, gnutls_ocsp_print_formats_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>resp</var>: The data to be printed
</p>
<p><var>format</var>: Indicate the format to use
</p>
<p><var>out</var>: Newly allocated datum with (0) terminated string.
</p>
<p>This function will pretty print a OCSP response, suitable for
display to a human.
</p>
<p>If the format is <code>GNUTLS_OCSP_PRINT_FULL</code>  then all fields of the
response will be output, on multiple lines.
</p>
<p>The output  <code>out</code> -&gt;data needs to be deallocate using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fverify-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_verify</h4>
<a name="gnutls_005focsp_005fresp_005fverify"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fverify"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_verify</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, gnutls_x509_trust_list_t <var>trustlist</var>, unsigned int * <var>verify</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p><var>trustlist</var>: trust anchors as a <code>gnutls_x509_trust_list_t</code>  type
</p>
<p><var>verify</var>: output variable with verification status, an <code>gnutls_ocsp_verify_reason_t</code> 
</p>
<p><var>flags</var>: verification flags, 0 for now.
</p>
<p>Verify signature of the Basic OCSP Response against the public key
in the certificate of a trusted signer.  The  <code>trustlist</code> should be
populated with trust anchors.  The function will extract the signer
certificate from the Basic OCSP Response and will verify it against
the  <code>trustlist</code> .  A trusted signer is a certificate that is either
in  <code>trustlist</code> , or it is signed directly by a certificate in
 <code>trustlist</code> and has the id-ad-ocspSigning Extended Key Usage bit
set.
</p>
<p>The output  <code>verify</code> variable will hold verification status codes
(e.g., <code>GNUTLS_OCSP_VERIFY_SIGNER_NOT_FOUND</code> ,
<code>GNUTLS_OCSP_VERIFY_INSECURE_ALGORITHM</code> ) which are only valid if the
function returned <code>GNUTLS_E_SUCCESS</code> .
</p>
<p>Note that the function returns <code>GNUTLS_E_SUCCESS</code>  even when
verification failed.  The caller must always inspect the  <code>verify</code> variable to find out the verification status.
</p>
<p>The  <code>flags</code> variable should be 0 for now.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005focsp_005fresp_005fverify_005fdirect-1"></a>
<h4 class="subheading">gnutls_ocsp_resp_verify_direct</h4>
<a name="gnutls_005focsp_005fresp_005fverify_005fdirect"></a><dl>
<dt><a name="index-gnutls_005focsp_005fresp_005fverify_005fdirect"></a>Function: <em>int</em> <strong>gnutls_ocsp_resp_verify_direct</strong> <em>(gnutls_ocsp_resp_t <var>resp</var>, gnutls_x509_crt_t <var>issuer</var>, unsigned int * <var>verify</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>resp</var>: should contain a <code>gnutls_ocsp_resp_t</code>  type
</p>
<p><var>issuer</var>: certificate believed to have signed the response
</p>
<p><var>verify</var>: output variable with verification status, an <code>gnutls_ocsp_verify_reason_t</code> 
</p>
<p><var>flags</var>: verification flags, 0 for now.
</p>
<p>Verify signature of the Basic OCSP Response against the public key
in the  <code>issuer</code> certificate.
</p>
<p>The output  <code>verify</code> variable will hold verification status codes
(e.g., <code>GNUTLS_OCSP_VERIFY_SIGNER_NOT_FOUND</code> ,
<code>GNUTLS_OCSP_VERIFY_INSECURE_ALGORITHM</code> ) which are only valid if the
function returned <code>GNUTLS_E_SUCCESS</code> .
</p>
<p>Note that the function returns <code>GNUTLS_E_SUCCESS</code>  even when
verification failed.  The caller must always inspect the  <code>verify</code> variable to find out the verification status.
</p>
<p>The  <code>flags</code> variable should be 0 for now.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>


<hr>
<a name="OpenPGP-API"></a>
<div class="header">
<p>
Next: <a href="#PKCS-12-API" accesskey="n" rel="next">PKCS 12 API</a>, Previous: <a href="#OCSP-API" accesskey="p" rel="prev">OCSP API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="OpenPGP-API-1"></a>
<h3 class="section">E.6 <acronym>OpenPGP</acronym> API</h3>
<a name="index-OpenPGP-API"></a>

<p>The following functions are to be used for <acronym>OpenPGP</acronym>
certificate handling.  Their prototypes lie in
<samp>gnutls/openpgp.h</samp>.
</p>

<a name="gnutls_005fcertificate_005fget_005fopenpgp_005fcrt-1"></a>
<h4 class="subheading">gnutls_certificate_get_openpgp_crt</h4>
<a name="gnutls_005fcertificate_005fget_005fopenpgp_005fcrt"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fget_005fopenpgp_005fcrt"></a>Function: <em>int</em> <strong>gnutls_certificate_get_openpgp_crt</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, unsigned <var>index</var>, gnutls_openpgp_crt_t ** <var>crt_list</var>, unsigned * <var>crt_list_size</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>index</var>: The index of the certificate list to obtain.
</p>
<p><var>crt_list</var>: Where to store the certificate list.
</p>
<p><var>crt_list_size</var>: &ndash; undescribed &ndash;
</p>
<p>Obtains a X.509 certificate list that has been stored in  <code>res</code> with one of
<code>gnutls_certificate_set_openpgp_key()</code> ,
<code>gnutls_certificate_set_openpgp_key_file()</code> ,
<code>gnutls_certificate_set_openpgp_key_file2()</code> ,
<code>gnutls_certificate_set_openpgp_key_mem()</code> , or
<code>gnutls_certificate_set_openpgp_key_mem2()</code> .  Each certificate in the
returned certificate list must be deallocated with
<code>gnutls_openpgp_crt_deinit()</code> , and the list itself must be freed with
<code>gnutls_free()</code> .
</p>
<p>If there is no certificate with the given index,
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned. If the certificate
with the given index is not a X.509 certificate, <code>GNUTLS_E_INVALID_REQUEST</code> 
is returned.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fget_005fopenpgp_005fkey-1"></a>
<h4 class="subheading">gnutls_certificate_get_openpgp_key</h4>
<a name="gnutls_005fcertificate_005fget_005fopenpgp_005fkey"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fget_005fopenpgp_005fkey"></a>Function: <em>int</em> <strong>gnutls_certificate_get_openpgp_key</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, unsigned <var>index</var>, gnutls_openpgp_privkey_t * <var>key</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>index</var>: The index of the key to obtain.
</p>
<p><var>key</var>: Location to store the key.
</p>
<p>Obtains a OpenPGP private key that has been stored in  <code>res</code> with one of
<code>gnutls_certificate_set_openpgp_key()</code> ,
<code>gnutls_certificate_set_openpgp_key_file()</code> ,
<code>gnutls_certificate_set_openpgp_key_file2()</code> ,
<code>gnutls_certificate_set_openpgp_key_mem()</code> , or
<code>gnutls_certificate_set_openpgp_key_mem2()</code> .
The returned key must be deallocated with <code>gnutls_openpgp_privkey_deinit()</code> 
when no longer needed.
</p>
<p>If there is no key with the given index,
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  is returned. If the key with the
given index is not a X.509 key, <code>GNUTLS_E_INVALID_REQUEST</code>  is returned.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkey-1"></a>
<h4 class="subheading">gnutls_certificate_set_openpgp_key</h4>
<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkey"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fopenpgp_005fkey"></a>Function: <em>int</em> <strong>gnutls_certificate_set_openpgp_key</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, gnutls_openpgp_crt_t <var>crt</var>, gnutls_openpgp_privkey_t <var>pkey</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>crt</var>: contains an openpgp public key
</p>
<p><var>pkey</var>: is an openpgp private key
</p>
<p>This function sets a certificate/private key pair in the
gnutls_certificate_credentials_t type.  This function may be
called more than once (in case multiple keys/certificates exist
for the server).
</p>
<p>Note that this function requires that the preferred key ids have
been set and be used. See <code>gnutls_openpgp_crt_set_preferred_key_id()</code> .
Otherwise the master key will be used.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005ffile-1"></a>
<h4 class="subheading">gnutls_certificate_set_openpgp_key_file</h4>
<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005ffile"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005ffile"></a>Function: <em>int</em> <strong>gnutls_certificate_set_openpgp_key_file</strong> <em>(gnutls_certificate_credentials_t      <var>res</var>, const char * <var>certfile</var>, const char * <var>keyfile</var>, gnutls_openpgp_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>res</var>: the destination context to save the data.
</p>
<p><var>certfile</var>: the file that contains the public key.
</p>
<p><var>keyfile</var>: the file that contains the secret key.
</p>
<p><var>format</var>: the format of the keys
</p>
<p>This funtion is used to load OpenPGP keys into the GnuTLS
credentials structure. The file should contain at least one valid non encrypted subkey.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005ffile2-1"></a>
<h4 class="subheading">gnutls_certificate_set_openpgp_key_file2</h4>
<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005ffile2"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005ffile2"></a>Function: <em>int</em> <strong>gnutls_certificate_set_openpgp_key_file2</strong> <em>(gnutls_certificate_credentials_t       <var>res</var>, const char * <var>certfile</var>, const char * <var>keyfile</var>, const char * <var>subkey_id</var>, gnutls_openpgp_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>res</var>: the destination context to save the data.
</p>
<p><var>certfile</var>: the file that contains the public key.
</p>
<p><var>keyfile</var>: the file that contains the secret key.
</p>
<p><var>subkey_id</var>: a hex encoded subkey id
</p>
<p><var>format</var>: the format of the keys
</p>
<p>This funtion is used to load OpenPGP keys into the GnuTLS credential 
structure. The file should contain at least one valid non encrypted subkey.
</p>
<p>The special keyword &quot;auto&quot; is also accepted as  <code>subkey_id</code> .  In that
case the <code>gnutls_openpgp_crt_get_auth_subkey()</code>  will be used to
retrieve the subkey.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005fmem-1"></a>
<h4 class="subheading">gnutls_certificate_set_openpgp_key_mem</h4>
<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005fmem"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005fmem"></a>Function: <em>int</em> <strong>gnutls_certificate_set_openpgp_key_mem</strong> <em>(gnutls_certificate_credentials_t            <var>res</var>, const gnutls_datum_t * <var>cert</var>, const gnutls_datum_t * <var>key</var>, gnutls_openpgp_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>res</var>: the destination context to save the data.
</p>
<p><var>cert</var>: the datum that contains the public key.
</p>
<p><var>key</var>: the datum that contains the secret key.
</p>
<p><var>format</var>: the format of the keys
</p>
<p>This funtion is used to load OpenPGP keys into the GnuTLS credential 
structure. The datum should contain at least one valid non encrypted subkey.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005fmem2-1"></a>
<h4 class="subheading">gnutls_certificate_set_openpgp_key_mem2</h4>
<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005fmem2"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005fmem2"></a>Function: <em>int</em> <strong>gnutls_certificate_set_openpgp_key_mem2</strong> <em>(gnutls_certificate_credentials_t      <var>res</var>, const gnutls_datum_t * <var>cert</var>, const gnutls_datum_t * <var>key</var>, const char * <var>subkey_id</var>, gnutls_openpgp_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>res</var>: the destination context to save the data.
</p>
<p><var>cert</var>: the datum that contains the public key.
</p>
<p><var>key</var>: the datum that contains the secret key.
</p>
<p><var>subkey_id</var>: a hex encoded subkey id
</p>
<p><var>format</var>: the format of the keys
</p>
<p>This funtion is used to load OpenPGP keys into the GnuTLS
credentials structure. The datum should contain at least one valid non encrypted subkey.
</p>
<p>The special keyword &quot;auto&quot; is also accepted as  <code>subkey_id</code> .  In that
case the <code>gnutls_openpgp_crt_get_auth_subkey()</code>  will be used to
retrieve the subkey.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkeyring_005ffile-1"></a>
<h4 class="subheading">gnutls_certificate_set_openpgp_keyring_file</h4>
<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkeyring_005ffile"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fopenpgp_005fkeyring_005ffile-1"></a>Function: <em>int</em> <strong>gnutls_certificate_set_openpgp_keyring_file</strong> <em>(gnutls_certificate_credentials_t <var>c</var>, const char * <var>file</var>, gnutls_openpgp_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>c</var>: A certificate credentials structure
</p>
<p><var>file</var>: filename of the keyring.
</p>
<p><var>format</var>: format of keyring.
</p>
<p>The function is used to set keyrings that will be used internally
by various OpenPGP functions. For example to find a key when it
is needed for an operations. The keyring will also be used at the
verification functions.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkeyring_005fmem-1"></a>
<h4 class="subheading">gnutls_certificate_set_openpgp_keyring_mem</h4>
<a name="gnutls_005fcertificate_005fset_005fopenpgp_005fkeyring_005fmem"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fopenpgp_005fkeyring_005fmem"></a>Function: <em>int</em> <strong>gnutls_certificate_set_openpgp_keyring_mem</strong> <em>(gnutls_certificate_credentials_t         <var>c</var>, const uint8_t * <var>data</var>, size_t <var>dlen</var>, gnutls_openpgp_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>c</var>: A certificate credentials structure
</p>
<p><var>data</var>: buffer with keyring data.
</p>
<p><var>dlen</var>: length of data buffer.
</p>
<p><var>format</var>: the format of the keyring
</p>
<p>The function is used to set keyrings that will be used internally
by various OpenPGP functions. For example to find a key when it
is needed for an operations. The keyring will also be used at the
verification functions.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fcheck_005femail-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_check_email</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fcheck_005femail"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fcheck_005femail"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_check_email</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, const char * <var>email</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>key</var>: should contain a <code>gnutls_openpgp_crt_t</code>  type
</p>
<p><var>email</var>: A null terminated string that contains an RFC822 address (email)
</p>
<p><var>flags</var>: gnutls_certificate_verify_flags
</p>
<p>This function will check if the given key&rsquo;s owner matches the
given email address. 
</p>
<p><strong>Returns:</strong> non-zero for a successful match, and zero on failure.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fcheck_005fhostname-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_check_hostname</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fcheck_005fhostname"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fcheck_005fhostname"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_check_hostname</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, const char * <var>hostname</var>)</em></dt>
<dd><p><var>key</var>: should contain a <code>gnutls_openpgp_crt_t</code>  type
</p>
<p><var>hostname</var>: A null terminated string that contains a DNS name
</p>
<p>This function will check if the given key&rsquo;s owner matches the
given hostname. This is a basic implementation of the matching
described in RFC2818 (HTTPS), which takes into account wildcards.
</p>
<p><strong>Returns:</strong> non-zero for a successful match, and zero on failure.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fcheck_005fhostname2-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_check_hostname2</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fcheck_005fhostname2"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fcheck_005fhostname2"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_check_hostname2</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, const char * <var>hostname</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>key</var>: should contain a <code>gnutls_openpgp_crt_t</code>  type
</p>
<p><var>hostname</var>: A null terminated string that contains a DNS name
</p>
<p><var>flags</var>: gnutls_certificate_verify_flags
</p>
<p>This function will check if the given key&rsquo;s owner matches the
given hostname. 
</p>
<p>Unless, the flag <code>GNUTLS_VERIFY_DO_NOT_ALLOW_WILDCARDS</code>  is specified,
wildcards are only considered if the domain name consists of three
components or more, and the wildcard starts at the leftmost position.
</p>
<p><strong>Returns:</strong> non-zero for a successful match, and zero on failure.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fdeinit-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_deinit</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_openpgp_crt_deinit</strong> <em>(gnutls_openpgp_crt_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: A pointer to the type to be initialized
</p>
<p>This function will deinitialize a key structure.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fexport-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_export</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fexport"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fexport"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_export</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, gnutls_openpgp_crt_fmt_t <var>format</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>key</var>: Holds the key.
</p>
<p><var>format</var>: One of gnutls_openpgp_crt_fmt_t elements.
</p>
<p><var>output_data</var>: will contain the raw or base64 encoded key
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will
be replaced by the actual size of parameters)
</p>
<p>This function will convert the given key to RAW or Base64 format.
If the buffer provided is not long enough to hold the output, then
<code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  will be returned.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fexport2-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_export2</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fexport2"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fexport2"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_export2</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, gnutls_openpgp_crt_fmt_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>key</var>: Holds the key.
</p>
<p><var>format</var>: One of gnutls_openpgp_crt_fmt_t elements.
</p>
<p><var>out</var>: will contain the raw or base64 encoded key
</p>
<p>This function will convert the given key to RAW or Base64 format.
The output buffer is allocated using <code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fauth_005fsubkey-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_auth_subkey</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fauth_005fsubkey"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fauth_005fsubkey"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_auth_subkey</strong> <em>(gnutls_openpgp_crt_t <var>crt</var>, gnutls_openpgp_keyid_t <var>keyid</var>, unsigned int <var>flag</var>)</em></dt>
<dd><p><var>crt</var>: the structure that contains the OpenPGP public key.
</p>
<p><var>keyid</var>: the struct to save the keyid.
</p>
<p><var>flag</var>: Non-zero indicates that a valid subkey is always returned.
</p>
<p>Returns the 64-bit keyID of the first valid OpenPGP subkey marked
for authentication.  If flag is non-zero and no authentication
subkey exists, then a valid subkey will be returned even if it is
not marked for authentication.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fcreation_005ftime-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_creation_time</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fcreation_005ftime"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fcreation_005ftime"></a>Function: <em>time_t</em> <strong>gnutls_openpgp_crt_get_creation_time</strong> <em>(gnutls_openpgp_crt_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p>Get key creation time.
</p>
<p><strong>Returns:</strong> the timestamp when the OpenPGP key was created.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fexpiration_005ftime-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_expiration_time</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fexpiration_005ftime"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fexpiration_005ftime"></a>Function: <em>time_t</em> <strong>gnutls_openpgp_crt_get_expiration_time</strong> <em>(gnutls_openpgp_crt_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p>Get key expiration time.  A value of &rsquo;0&rsquo; means that the key doesn&rsquo;t
expire at all.
</p>
<p><strong>Returns:</strong> the time when the OpenPGP key expires.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005ffingerprint-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_fingerprint</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005ffingerprint"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005ffingerprint"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_fingerprint</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, void * <var>fpr</var>, size_t * <var>fprlen</var>)</em></dt>
<dd><p><var>key</var>: the raw data that contains the OpenPGP public key.
</p>
<p><var>fpr</var>: the buffer to save the fingerprint, must hold at least 20 bytes.
</p>
<p><var>fprlen</var>: the integer to save the length of the fingerprint.
</p>
<p>Get key fingerprint.  Depending on the algorithm, the fingerprint
can be 16 or 20 bytes.
</p>
<p><strong>Returns:</strong> On success, 0 is returned.  Otherwise, an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_key_id</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_key_id</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, gnutls_openpgp_keyid_t <var>keyid</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p><var>keyid</var>: the buffer to save the keyid.
</p>
<p>Get key id string.
</p>
<p><strong>Returns:</strong> the 64-bit keyID of the OpenPGP key.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fkey_005fusage-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_key_usage</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fkey_005fusage"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fkey_005fusage"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_key_usage</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, unsigned int * <var>key_usage</var>)</em></dt>
<dd><p><var>key</var>: should contain a gnutls_openpgp_crt_t type
</p>
<p><var>key_usage</var>: where the key usage bits will be stored
</p>
<p>This function will return certificate&rsquo;s key usage, by checking the
key algorithm. The key usage value will ORed values of the:
<code>GNUTLS_KEY_DIGITAL_SIGNATURE</code> , <code>GNUTLS_KEY_KEY_ENCIPHERMENT</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_name</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fname"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_name</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, int <var>idx</var>, char * <var>buf</var>, size_t * <var>sizeof_buf</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p><var>idx</var>: the index of the ID to extract
</p>
<p><var>buf</var>: a pointer to a structure to hold the name, may be <code>NULL</code> 
to only get the  <code>sizeof_buf</code> .
</p>
<p><var>sizeof_buf</var>: holds the maximum size of  <code>buf</code> , on return hold the
actual/required size of  <code>buf</code> .
</p>
<p>Extracts the userID from the parsed OpenPGP key.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, and if the index of the ID
does not exist <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> , or an
error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fpk_005falgorithm-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_pk_algorithm</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fpk_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fpk_005falgorithm"></a>Function: <em>gnutls_pk_algorithm_t</em> <strong>gnutls_openpgp_crt_get_pk_algorithm</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, unsigned int * <var>bits</var>)</em></dt>
<dd><p><var>key</var>: is an OpenPGP key
</p>
<p><var>bits</var>: if bits is non null it will hold the size of the parameters&rsquo; in bits
</p>
<p>This function will return the public key algorithm of an OpenPGP
certificate.
</p>
<p>If bits is non null, it should have enough size to hold the parameters
size in bits. For RSA the bits returned is the modulus.
For DSA the bits returned are of the public exponent.
</p>
<p><strong>Returns:</strong> a member of the <code>gnutls_pk_algorithm_t</code>  enumeration on
success, or GNUTLS_PK_UNKNOWN on error.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fpk_005fdsa_005fraw-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_pk_dsa_raw</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fpk_005fdsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fpk_005fdsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_pk_dsa_raw</strong> <em>(gnutls_openpgp_crt_t <var>crt</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>g</var>, gnutls_datum_t * <var>y</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>p</var>: will hold the p
</p>
<p><var>q</var>: will hold the q
</p>
<p><var>g</var>: will hold the g
</p>
<p><var>y</var>: will hold the y
</p>
<p>This function will export the DSA public key&rsquo;s parameters found in
the given certificate.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fpk_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_pk_rsa_raw</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fpk_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fpk_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_pk_rsa_raw</strong> <em>(gnutls_openpgp_crt_t <var>crt</var>, gnutls_datum_t * <var>m</var>, gnutls_datum_t * <var>e</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>m</var>: will hold the modulus
</p>
<p><var>e</var>: will hold the public exponent
</p>
<p>This function will export the RSA public key&rsquo;s parameters found in
the given structure.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fpreferred_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_preferred_key_id</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fpreferred_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fpreferred_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_preferred_key_id</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, gnutls_openpgp_keyid_t <var>keyid</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p><var>keyid</var>: the struct to save the keyid.
</p>
<p>Get preferred key id.  If it hasn&rsquo;t been set it returns
<code>GNUTLS_E_INVALID_REQUEST</code> .
</p>
<p><strong>Returns:</strong> the 64-bit preferred keyID of the OpenPGP key.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005frevoked_005fstatus-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_revoked_status</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005frevoked_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005frevoked_005fstatus"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_revoked_status</strong> <em>(gnutls_openpgp_crt_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p>Get revocation status of key.
</p>
<p><strong>Returns:</strong> true (1) if the key has been revoked, or false (0) if it
has not.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fcount-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_subkey_count</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fcount"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fcount"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_subkey_count</strong> <em>(gnutls_openpgp_crt_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: is an OpenPGP key
</p>
<p>This function will return the number of subkeys present in the
given OpenPGP certificate.
</p>
<p><strong>Returns:</strong> the number of subkeys, or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fcreation_005ftime-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_subkey_creation_time</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fcreation_005ftime"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fcreation_005ftime"></a>Function: <em>time_t</em> <strong>gnutls_openpgp_crt_get_subkey_creation_time</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, unsigned int <var>idx</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p><var>idx</var>: the subkey index
</p>
<p>Get subkey creation time.
</p>
<p><strong>Returns:</strong> the timestamp when the OpenPGP sub-key was created.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fexpiration_005ftime-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_subkey_expiration_time</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fexpiration_005ftime"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fexpiration_005ftime"></a>Function: <em>time_t</em> <strong>gnutls_openpgp_crt_get_subkey_expiration_time</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, unsigned int <var>idx</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p><var>idx</var>: the subkey index
</p>
<p>Get subkey expiration time.  A value of &rsquo;0&rsquo; means that the key
doesn&rsquo;t expire at all.
</p>
<p><strong>Returns:</strong> the time when the OpenPGP key expires.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005ffingerprint-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_subkey_fingerprint</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005ffingerprint"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005ffingerprint"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_subkey_fingerprint</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, unsigned int <var>idx</var>, void * <var>fpr</var>, size_t * <var>fprlen</var>)</em></dt>
<dd><p><var>key</var>: the raw data that contains the OpenPGP public key.
</p>
<p><var>idx</var>: the subkey index
</p>
<p><var>fpr</var>: the buffer to save the fingerprint, must hold at least 20 bytes.
</p>
<p><var>fprlen</var>: the integer to save the length of the fingerprint.
</p>
<p>Get key fingerprint of a subkey.  Depending on the algorithm, the
fingerprint can be 16 or 20 bytes.
</p>
<p><strong>Returns:</strong> On success, 0 is returned.  Otherwise, an error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fid-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_subkey_id</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fid"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_subkey_id</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, unsigned int <var>idx</var>, gnutls_openpgp_keyid_t <var>keyid</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p><var>idx</var>: the subkey index
</p>
<p><var>keyid</var>: the buffer to save the keyid.
</p>
<p>Get the subkey&rsquo;s key-id.
</p>
<p><strong>Returns:</strong> the 64-bit keyID of the OpenPGP key.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fidx-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_subkey_idx</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fidx"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fidx"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_subkey_idx</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, const gnutls_openpgp_keyid_t <var>keyid</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p><var>keyid</var>: the keyid.
</p>
<p>Get subkey&rsquo;s index.
</p>
<p><strong>Returns:</strong> the index of the subkey or a negative error value.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fpk_005falgorithm-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_subkey_pk_algorithm</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fpk_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fpk_005falgorithm"></a>Function: <em>gnutls_pk_algorithm_t</em> <strong>gnutls_openpgp_crt_get_subkey_pk_algorithm</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, unsigned int <var>idx</var>, unsigned int * <var>bits</var>)</em></dt>
<dd><p><var>key</var>: is an OpenPGP key
</p>
<p><var>idx</var>: is the subkey index
</p>
<p><var>bits</var>: if bits is non null it will hold the size of the parameters&rsquo; in bits
</p>
<p>This function will return the public key algorithm of a subkey of an OpenPGP
certificate.
</p>
<p>If bits is non null, it should have enough size to hold the
parameters size in bits.  For RSA the bits returned is the modulus.
For DSA the bits returned are of the public exponent.
</p>
<p><strong>Returns:</strong> a member of the <code>gnutls_pk_algorithm_t</code>  enumeration on
success, or GNUTLS_PK_UNKNOWN on error.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fpk_005fdsa_005fraw-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_subkey_pk_dsa_raw</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fpk_005fdsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fpk_005fdsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_subkey_pk_dsa_raw</strong> <em>(gnutls_openpgp_crt_t <var>crt</var>, unsigned int <var>idx</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>g</var>, gnutls_datum_t * <var>y</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>idx</var>: Is the subkey index
</p>
<p><var>p</var>: will hold the p
</p>
<p><var>q</var>: will hold the q
</p>
<p><var>g</var>: will hold the g
</p>
<p><var>y</var>: will hold the y
</p>
<p>This function will export the DSA public key&rsquo;s parameters found in
the given certificate.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fpk_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_subkey_pk_rsa_raw</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fpk_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fpk_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_subkey_pk_rsa_raw</strong> <em>(gnutls_openpgp_crt_t <var>crt</var>, unsigned int <var>idx</var>, gnutls_datum_t * <var>m</var>, gnutls_datum_t * <var>e</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>idx</var>: Is the subkey index
</p>
<p><var>m</var>: will hold the modulus
</p>
<p><var>e</var>: will hold the public exponent
</p>
<p>This function will export the RSA public key&rsquo;s parameters found in
the given structure.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005frevoked_005fstatus-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_subkey_revoked_status</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005frevoked_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005frevoked_005fstatus"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_subkey_revoked_status</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, unsigned int <var>idx</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p><var>idx</var>: is the subkey index
</p>
<p>Get subkey revocation status.  A negative error code indicates an error.
</p>
<p><strong>Returns:</strong> true (1) if the key has been revoked, or false (0) if it
has not.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fusage-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_subkey_usage</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fusage"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fusage"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_subkey_usage</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, unsigned int <var>idx</var>, unsigned int * <var>key_usage</var>)</em></dt>
<dd><p><var>key</var>: should contain a gnutls_openpgp_crt_t type
</p>
<p><var>idx</var>: the subkey index
</p>
<p><var>key_usage</var>: where the key usage bits will be stored
</p>
<p>This function will return certificate&rsquo;s key usage, by checking the
key algorithm.  The key usage value will ORed values of
<code>GNUTLS_KEY_DIGITAL_SIGNATURE</code>  or <code>GNUTLS_KEY_KEY_ENCIPHERMENT</code> .
</p>
<p>A negative error code may be returned in case of parsing error.
</p>
<p><strong>Returns:</strong> key usage value.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fget_005fversion-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_get_version</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fget_005fversion"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fget_005fversion"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_get_version</strong> <em>(gnutls_openpgp_crt_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p>Extract the version of the OpenPGP key.
</p>
<p><strong>Returns:</strong> the version number is returned, or a negative error code on errors.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fimport-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_import</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fimport"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fimport"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_import</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, const gnutls_datum_t * <var>data</var>, gnutls_openpgp_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>key</var>: The structure to store the parsed key.
</p>
<p><var>data</var>: The RAW or BASE64 encoded key.
</p>
<p><var>format</var>: One of gnutls_openpgp_crt_fmt_t elements.
</p>
<p>This function will convert the given RAW or Base64 encoded key to
the native <code>gnutls_openpgp_crt_t</code>  format. The output will be stored
in &rsquo;key&rsquo;.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005finit-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_init</h4>
<a name="gnutls_005fopenpgp_005fcrt_005finit"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005finit"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_init</strong> <em>(gnutls_openpgp_crt_t * <var>key</var>)</em></dt>
<dd><p><var>key</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize an OpenPGP key structure.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fprint-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_print</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fprint"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fprint"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_print</strong> <em>(gnutls_openpgp_crt_t <var>cert</var>, gnutls_certificate_print_formats_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>cert</var>: The structure to be printed
</p>
<p><var>format</var>: Indicate the format to use
</p>
<p><var>out</var>: Newly allocated datum with (0) terminated string.
</p>
<p>This function will pretty print an OpenPGP certificate, suitable
for display to a human.
</p>
<p>The format should be (0) for future compatibility.
</p>
<p>The output  <code>out</code> needs to be deallocate using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fset_005fpreferred_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_set_preferred_key_id</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fset_005fpreferred_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fset_005fpreferred_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_set_preferred_key_id</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, const gnutls_openpgp_keyid_t <var>keyid</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p><var>keyid</var>: the selected keyid
</p>
<p>This allows setting a preferred key id for the given certificate.
This key will be used by functions that involve key handling.
</p>
<p>If the provided  <code>keyid</code> is <code>NULL</code>  then the master key is
set as preferred.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fverify_005fring-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_verify_ring</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fverify_005fring"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fverify_005fring-1"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_verify_ring</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, gnutls_openpgp_keyring_t <var>keyring</var>, unsigned int <var>flags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>key</var>: the structure that holds the key.
</p>
<p><var>keyring</var>: holds the keyring to check against
</p>
<p><var>flags</var>: unused (should be 0)
</p>
<p><var>verify</var>: will hold the certificate verification output.
</p>
<p>Verify all signatures in the key, using the given set of keys
(keyring).
</p>
<p>The key verification output will be put in  <code>verify</code> and will be one
or more of the <code>gnutls_certificate_status_t</code>  enumerated elements
bitwise or&rsquo;d.
</p>
<p>Note that this function does not verify using any &quot;web of trust&quot;.
You may use GnuPG for that purpose, or any other external PGP
application.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fcrt_005fverify_005fself-1"></a>
<h4 class="subheading">gnutls_openpgp_crt_verify_self</h4>
<a name="gnutls_005fopenpgp_005fcrt_005fverify_005fself"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fcrt_005fverify_005fself-1"></a>Function: <em>int</em> <strong>gnutls_openpgp_crt_verify_self</strong> <em>(gnutls_openpgp_crt_t <var>key</var>, unsigned int <var>flags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>key</var>: the structure that holds the key.
</p>
<p><var>flags</var>: unused (should be 0)
</p>
<p><var>verify</var>: will hold the key verification output.
</p>
<p>Verifies the self signature in the key.  The key verification
output will be put in  <code>verify</code> and will be one or more of the
gnutls_certificate_status_t enumerated elements bitwise or&rsquo;d.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fkeyring_005fcheck_005fid-1"></a>
<h4 class="subheading">gnutls_openpgp_keyring_check_id</h4>
<a name="gnutls_005fopenpgp_005fkeyring_005fcheck_005fid"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fkeyring_005fcheck_005fid"></a>Function: <em>int</em> <strong>gnutls_openpgp_keyring_check_id</strong> <em>(gnutls_openpgp_keyring_t <var>ring</var>, const gnutls_openpgp_keyid_t <var>keyid</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>ring</var>: holds the keyring to check against
</p>
<p><var>keyid</var>: will hold the keyid to check for.
</p>
<p><var>flags</var>: unused (should be 0)
</p>
<p>Check if a given key ID exists in the keyring.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success (if keyid exists) and a
negative error code on failure.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fkeyring_005fdeinit-1"></a>
<h4 class="subheading">gnutls_openpgp_keyring_deinit</h4>
<a name="gnutls_005fopenpgp_005fkeyring_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fkeyring_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_openpgp_keyring_deinit</strong> <em>(gnutls_openpgp_keyring_t <var>keyring</var>)</em></dt>
<dd><p><var>keyring</var>: A pointer to the type to be initialized
</p>
<p>This function will deinitialize a keyring structure.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fkeyring_005fget_005fcrt-1"></a>
<h4 class="subheading">gnutls_openpgp_keyring_get_crt</h4>
<a name="gnutls_005fopenpgp_005fkeyring_005fget_005fcrt"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fkeyring_005fget_005fcrt"></a>Function: <em>int</em> <strong>gnutls_openpgp_keyring_get_crt</strong> <em>(gnutls_openpgp_keyring_t <var>ring</var>, unsigned int <var>idx</var>, gnutls_openpgp_crt_t * <var>cert</var>)</em></dt>
<dd><p><var>ring</var>: Holds the keyring.
</p>
<p><var>idx</var>: the index of the certificate to export
</p>
<p><var>cert</var>: An uninitialized <code>gnutls_openpgp_crt_t</code>  type
</p>
<p>This function will extract an OpenPGP certificate from the given
keyring.  If the index given is out of range
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be returned. The
returned structure needs to be deinited.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fkeyring_005fget_005fcrt_005fcount-1"></a>
<h4 class="subheading">gnutls_openpgp_keyring_get_crt_count</h4>
<a name="gnutls_005fopenpgp_005fkeyring_005fget_005fcrt_005fcount"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fkeyring_005fget_005fcrt_005fcount"></a>Function: <em>int</em> <strong>gnutls_openpgp_keyring_get_crt_count</strong> <em>(gnutls_openpgp_keyring_t <var>ring</var>)</em></dt>
<dd><p><var>ring</var>: is an OpenPGP key ring
</p>
<p>This function will return the number of OpenPGP certificates
present in the given keyring.
</p>
<p><strong>Returns:</strong> the number of subkeys, or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fkeyring_005fimport-1"></a>
<h4 class="subheading">gnutls_openpgp_keyring_import</h4>
<a name="gnutls_005fopenpgp_005fkeyring_005fimport"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fkeyring_005fimport"></a>Function: <em>int</em> <strong>gnutls_openpgp_keyring_import</strong> <em>(gnutls_openpgp_keyring_t <var>keyring</var>, const gnutls_datum_t * <var>data</var>, gnutls_openpgp_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>keyring</var>: The structure to store the parsed key.
</p>
<p><var>data</var>: The RAW or BASE64 encoded keyring.
</p>
<p><var>format</var>: One of <code>gnutls_openpgp_keyring_fmt</code>  elements.
</p>
<p>This function will convert the given RAW or Base64 encoded keyring
to the native <code>gnutls_openpgp_keyring_t</code>  format.  The output will be
stored in &rsquo;keyring&rsquo;.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fkeyring_005finit-1"></a>
<h4 class="subheading">gnutls_openpgp_keyring_init</h4>
<a name="gnutls_005fopenpgp_005fkeyring_005finit"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fkeyring_005finit"></a>Function: <em>int</em> <strong>gnutls_openpgp_keyring_init</strong> <em>(gnutls_openpgp_keyring_t * <var>keyring</var>)</em></dt>
<dd><p><var>keyring</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize an keyring structure.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fdeinit-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_deinit</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_openpgp_privkey_deinit</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: A pointer to the type to be initialized
</p>
<p>This function will deinitialize a key structure.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fexport-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_export</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fexport"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fexport"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_export</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>, gnutls_openpgp_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>key</var>: Holds the key.
</p>
<p><var>format</var>: One of gnutls_openpgp_crt_fmt_t elements.
</p>
<p><var>password</var>: the password that will be used to encrypt the key. (unused for now)
</p>
<p><var>flags</var>: (0) for future compatibility
</p>
<p><var>output_data</var>: will contain the key base64 encoded or raw
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will convert the given key to RAW or Base64 format.
If the buffer provided is not long enough to hold the output, then
GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fexport2-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_export2</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fexport2"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fexport2"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_export2</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>, gnutls_openpgp_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>key</var>: Holds the key.
</p>
<p><var>format</var>: One of gnutls_openpgp_crt_fmt_t elements.
</p>
<p><var>password</var>: the password that will be used to encrypt the key. (unused for now)
</p>
<p><var>flags</var>: (0) for future compatibility
</p>
<p><var>out</var>: will contain the raw or based64 encoded key
</p>
<p>This function will convert the given key to RAW or Base64 format.
The output buffer is allocated using <code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fexport_005fdsa_005fraw-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_export_dsa_raw</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fexport_005fdsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fexport_005fdsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_export_dsa_raw</strong> <em>(gnutls_openpgp_privkey_t <var>pkey</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>g</var>, gnutls_datum_t * <var>y</var>, gnutls_datum_t * <var>x</var>)</em></dt>
<dd><p><var>pkey</var>: Holds the certificate
</p>
<p><var>p</var>: will hold the p
</p>
<p><var>q</var>: will hold the q
</p>
<p><var>g</var>: will hold the g
</p>
<p><var>y</var>: will hold the y
</p>
<p><var>x</var>: will hold the x
</p>
<p>This function will export the DSA private key&rsquo;s parameters found in
the given certificate.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fexport_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_export_rsa_raw</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fexport_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fexport_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_export_rsa_raw</strong> <em>(gnutls_openpgp_privkey_t <var>pkey</var>, gnutls_datum_t * <var>m</var>, gnutls_datum_t * <var>e</var>, gnutls_datum_t * <var>d</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>u</var>)</em></dt>
<dd><p><var>pkey</var>: Holds the certificate
</p>
<p><var>m</var>: will hold the modulus
</p>
<p><var>e</var>: will hold the public exponent
</p>
<p><var>d</var>: will hold the private exponent
</p>
<p><var>p</var>: will hold the first prime (p)
</p>
<p><var>q</var>: will hold the second prime (q)
</p>
<p><var>u</var>: will hold the coefficient
</p>
<p>This function will export the RSA private key&rsquo;s parameters found in
the given structure.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fexport_005fsubkey_005fdsa_005fraw-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_export_subkey_dsa_raw</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fexport_005fsubkey_005fdsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fexport_005fsubkey_005fdsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_export_subkey_dsa_raw</strong> <em>(gnutls_openpgp_privkey_t <var>pkey</var>, unsigned int <var>idx</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>g</var>, gnutls_datum_t * <var>y</var>, gnutls_datum_t * <var>x</var>)</em></dt>
<dd><p><var>pkey</var>: Holds the certificate
</p>
<p><var>idx</var>: Is the subkey index
</p>
<p><var>p</var>: will hold the p
</p>
<p><var>q</var>: will hold the q
</p>
<p><var>g</var>: will hold the g
</p>
<p><var>y</var>: will hold the y
</p>
<p><var>x</var>: will hold the x
</p>
<p>This function will export the DSA private key&rsquo;s parameters found
in the given certificate.  The new parameters will be allocated
using <code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fexport_005fsubkey_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_export_subkey_rsa_raw</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fexport_005fsubkey_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fexport_005fsubkey_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_export_subkey_rsa_raw</strong> <em>(gnutls_openpgp_privkey_t <var>pkey</var>, unsigned int <var>idx</var>, gnutls_datum_t * <var>m</var>, gnutls_datum_t * <var>e</var>, gnutls_datum_t * <var>d</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>u</var>)</em></dt>
<dd><p><var>pkey</var>: Holds the certificate
</p>
<p><var>idx</var>: Is the subkey index
</p>
<p><var>m</var>: will hold the modulus
</p>
<p><var>e</var>: will hold the public exponent
</p>
<p><var>d</var>: will hold the private exponent
</p>
<p><var>p</var>: will hold the first prime (p)
</p>
<p><var>q</var>: will hold the second prime (q)
</p>
<p><var>u</var>: will hold the coefficient
</p>
<p>This function will export the RSA private key&rsquo;s parameters found in
the given structure.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005ffingerprint-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_fingerprint</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005ffingerprint"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005ffingerprint"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_get_fingerprint</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>, void * <var>fpr</var>, size_t * <var>fprlen</var>)</em></dt>
<dd><p><var>key</var>: the raw data that contains the OpenPGP secret key.
</p>
<p><var>fpr</var>: the buffer to save the fingerprint, must hold at least 20 bytes.
</p>
<p><var>fprlen</var>: the integer to save the length of the fingerprint.
</p>
<p>Get the fingerprint of the OpenPGP key. Depends on the
algorithm, the fingerprint can be 16 or 20 bytes.
</p>
<p><strong>Returns:</strong> On success, 0 is returned, or an error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_key_id</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_get_key_id</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>, gnutls_openpgp_keyid_t <var>keyid</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP secret key.
</p>
<p><var>keyid</var>: the buffer to save the keyid.
</p>
<p>Get key-id.
</p>
<p><strong>Returns:</strong> the 64-bit keyID of the OpenPGP key.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fpk_005falgorithm-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_pk_algorithm</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fpk_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005fpk_005falgorithm"></a>Function: <em>gnutls_pk_algorithm_t</em> <strong>gnutls_openpgp_privkey_get_pk_algorithm</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>, unsigned int * <var>bits</var>)</em></dt>
<dd><p><var>key</var>: is an OpenPGP key
</p>
<p><var>bits</var>: if bits is non null it will hold the size of the parameters&rsquo; in bits
</p>
<p>This function will return the public key algorithm of an OpenPGP
certificate.
</p>
<p>If bits is non null, it should have enough size to hold the parameters
size in bits. For RSA the bits returned is the modulus.
For DSA the bits returned are of the public exponent.
</p>
<p><strong>Returns:</strong> a member of the <code>gnutls_pk_algorithm_t</code>  enumeration on
success, or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fpreferred_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_preferred_key_id</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fpreferred_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005fpreferred_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_get_preferred_key_id</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>, gnutls_openpgp_keyid_t <var>keyid</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p><var>keyid</var>: the struct to save the keyid.
</p>
<p>Get the preferred key-id for the key.
</p>
<p><strong>Returns:</strong> the 64-bit preferred keyID of the OpenPGP key, or if it
hasn&rsquo;t been set it returns <code>GNUTLS_E_INVALID_REQUEST</code> .
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005frevoked_005fstatus-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_revoked_status</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005frevoked_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005frevoked_005fstatus"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_get_revoked_status</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP private key.
</p>
<p>Get revocation status of key.
</p>
<p><strong>Returns:</strong> true (1) if the key has been revoked, or false (0) if it
has not, or a negative error code indicates an error.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fcount-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_subkey_count</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fcount"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fcount"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_get_subkey_count</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: is an OpenPGP key
</p>
<p>This function will return the number of subkeys present in the
given OpenPGP certificate.
</p>
<p><strong>Returns:</strong> the number of subkeys, or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fcreation_005ftime-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_subkey_creation_time</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fcreation_005ftime"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fcreation_005ftime"></a>Function: <em>time_t</em> <strong>gnutls_openpgp_privkey_get_subkey_creation_time</strong> <em>(gnutls_openpgp_privkey_t       <var>key</var>, unsigned int <var>idx</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP private key.
</p>
<p><var>idx</var>: the subkey index
</p>
<p>Get subkey creation time.
</p>
<p><strong>Returns:</strong> the timestamp when the OpenPGP key was created.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fexpiration_005ftime-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_subkey_expiration_time</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fexpiration_005ftime"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fexpiration_005ftime"></a>Function: <em>time_t</em> <strong>gnutls_openpgp_privkey_get_subkey_expiration_time</strong> <em>(gnutls_openpgp_privkey_t         <var>key</var>, unsigned int <var>idx</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP private key.
</p>
<p><var>idx</var>: the subkey index
</p>
<p>Get subkey expiration time.  A value of &rsquo;0&rsquo; means that the key
doesn&rsquo;t expire at all.
</p>
<p><strong>Returns:</strong> the time when the OpenPGP key expires.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005ffingerprint-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_subkey_fingerprint</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005ffingerprint"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005ffingerprint"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_get_subkey_fingerprint</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>, unsigned int <var>idx</var>, void * <var>fpr</var>, size_t * <var>fprlen</var>)</em></dt>
<dd><p><var>key</var>: the raw data that contains the OpenPGP secret key.
</p>
<p><var>idx</var>: the subkey index
</p>
<p><var>fpr</var>: the buffer to save the fingerprint, must hold at least 20 bytes.
</p>
<p><var>fprlen</var>: the integer to save the length of the fingerprint.
</p>
<p>Get the fingerprint of an OpenPGP subkey.  Depends on the
algorithm, the fingerprint can be 16 or 20 bytes.
</p>
<p><strong>Returns:</strong> On success, 0 is returned, or an error code.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fid-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_subkey_id</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fid"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_get_subkey_id</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>, unsigned int <var>idx</var>, gnutls_openpgp_keyid_t <var>keyid</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP secret key.
</p>
<p><var>idx</var>: the subkey index
</p>
<p><var>keyid</var>: the buffer to save the keyid.
</p>
<p>Get the key-id for the subkey.
</p>
<p><strong>Returns:</strong> the 64-bit keyID of the OpenPGP key.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fidx-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_subkey_idx</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fidx"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fidx"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_get_subkey_idx</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>, const gnutls_openpgp_keyid_t <var>keyid</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP private key.
</p>
<p><var>keyid</var>: the keyid.
</p>
<p>Get index of subkey.
</p>
<p><strong>Returns:</strong> the index of the subkey or a negative error value.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fpk_005falgorithm-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_subkey_pk_algorithm</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fpk_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fpk_005falgorithm"></a>Function: <em>gnutls_pk_algorithm_t</em> <strong>gnutls_openpgp_privkey_get_subkey_pk_algorithm</strong> <em>(gnutls_openpgp_privkey_t             <var>key</var>, unsigned int <var>idx</var>, unsigned int * <var>bits</var>)</em></dt>
<dd><p><var>key</var>: is an OpenPGP key
</p>
<p><var>idx</var>: is the subkey index
</p>
<p><var>bits</var>: if bits is non null it will hold the size of the parameters&rsquo; in bits
</p>
<p>This function will return the public key algorithm of a subkey of an OpenPGP
certificate.
</p>
<p>If bits is non null, it should have enough size to hold the parameters
size in bits. For RSA the bits returned is the modulus.
For DSA the bits returned are of the public exponent.
</p>
<p><strong>Returns:</strong> a member of the <code>gnutls_pk_algorithm_t</code>  enumeration on
success, or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005frevoked_005fstatus-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_get_subkey_revoked_status</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005frevoked_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005frevoked_005fstatus"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_get_subkey_revoked_status</strong> <em>(gnutls_openpgp_privkey_t        <var>key</var>, unsigned int <var>idx</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP private key.
</p>
<p><var>idx</var>: is the subkey index
</p>
<p>Get revocation status of key.
</p>
<p><strong>Returns:</strong> true (1) if the key has been revoked, or false (0) if it
has not, or a negative error code indicates an error.
</p>
<p><strong>Since:</strong> 2.4.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fimport-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_import</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fimport"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fimport"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_import</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>, const gnutls_datum_t * <var>data</var>, gnutls_openpgp_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: The structure to store the parsed key.
</p>
<p><var>data</var>: The RAW or BASE64 encoded key.
</p>
<p><var>format</var>: One of <code>gnutls_openpgp_crt_fmt_t</code>  elements.
</p>
<p><var>password</var>: not used for now
</p>
<p><var>flags</var>: should be (0)
</p>
<p>This function will convert the given RAW or Base64 encoded key to
the native gnutls_openpgp_privkey_t format.  The output will be
stored in &rsquo;key&rsquo;.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005finit-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_init</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005finit"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005finit"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_init</strong> <em>(gnutls_openpgp_privkey_t * <var>key</var>)</em></dt>
<dd><p><var>key</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize an OpenPGP key structure.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an error code.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fsec_005fparam-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_sec_param</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fsec_005fparam"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fsec_005fparam"></a>Function: <em>gnutls_sec_param_t</em> <strong>gnutls_openpgp_privkey_sec_param</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: a key structure
</p>
<p>This function will return the security parameter appropriate with
this private key.
</p>
<p><strong>Returns:</strong> On success, a valid security parameter is returned otherwise
<code>GNUTLS_SEC_PARAM_UNKNOWN</code>  is returned.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fset_005fpreferred_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_set_preferred_key_id</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fset_005fpreferred_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fset_005fpreferred_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_set_preferred_key_id</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>, const gnutls_openpgp_keyid_t          <var>keyid</var>)</em></dt>
<dd><p><var>key</var>: the structure that contains the OpenPGP public key.
</p>
<p><var>keyid</var>: the selected keyid
</p>
<p>This allows setting a preferred key id for the given certificate.
This key will be used by functions that involve key handling.
</p>
<p>If the provided  <code>keyid</code> is <code>NULL</code>  then the master key is
set as preferred.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fset_005frecv_005fkey_005ffunction-1"></a>
<h4 class="subheading">gnutls_openpgp_set_recv_key_function</h4>
<a name="gnutls_005fopenpgp_005fset_005frecv_005fkey_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fset_005frecv_005fkey_005ffunction"></a>Function: <em>void</em> <strong>gnutls_openpgp_set_recv_key_function</strong> <em>(gnutls_session_t <var>session</var>, gnutls_openpgp_recv_key_func <var>func</var>)</em></dt>
<dd><p><var>session</var>: a TLS session
</p>
<p><var>func</var>: the callback
</p>
<p>This funtion will set a key retrieval function for OpenPGP keys. This
callback is only useful in server side, and will be used if the peer
sent a key fingerprint instead of a full key.
</p>
<p>The retrieved key must be allocated using <code>gnutls_malloc()</code> .
</p></dd></dl>


<hr>
<a name="PKCS-12-API"></a>
<div class="header">
<p>
Next: <a href="#PKCS-11-API" accesskey="n" rel="next">PKCS 11 API</a>, Previous: <a href="#OpenPGP-API" accesskey="p" rel="prev">OpenPGP API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="PKCS-12-API-1"></a>
<h3 class="section">E.7 PKCS 12 API</h3>

<p>The following functions are to be used for PKCS 12 handling.
Their prototypes lie in <samp>gnutls/pkcs12.h</samp>.
</p>

<a name="gnutls_005fpkcs12_005fbag_005fdecrypt-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_decrypt</h4>
<a name="gnutls_005fpkcs12_005fbag_005fdecrypt"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fdecrypt"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_decrypt</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, const char * <var>pass</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>pass</var>: The password used for encryption, must be ASCII.
</p>
<p>This function will decrypt the given encrypted bag and return 0 on
success.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fdeinit-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_deinit</h4>
<a name="gnutls_005fpkcs12_005fbag_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_pkcs12_bag_deinit</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>)</em></dt>
<dd><p><var>bag</var>: A pointer to the type to be initialized
</p>
<p>This function will deinitialize a PKCS12 Bag structure.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fenc_005finfo-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_enc_info</h4>
<a name="gnutls_005fpkcs12_005fbag_005fenc_005finfo"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fenc_005finfo"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_enc_info</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, unsigned int * <var>schema</var>, unsigned int * <var>cipher</var>, void * <var>salt</var>, unsigned int * <var>salt_size</var>, unsigned int * <var>iter_count</var>, char ** <var>oid</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>schema</var>: indicate the schema as one of <code>gnutls_pkcs_encrypt_flags_t</code> 
</p>
<p><var>cipher</var>: the cipher used as <code>gnutls_cipher_algorithm_t</code> 
</p>
<p><var>salt</var>: PBKDF2 salt (if non-NULL then  <code>salt_size</code> initially holds its size)
</p>
<p><var>salt_size</var>: PBKDF2 salt size
</p>
<p><var>iter_count</var>: PBKDF2 iteration count
</p>
<p><var>oid</var>: if non-NULL it will contain an allocated null-terminated variable with the OID
</p>
<p>This function will provide information on the encryption algorithms used
in an encrypted bag. If the structure algorithms
are unknown the code <code>GNUTLS_E_UNKNOWN_CIPHER_TYPE</code>  will be returned,
and only  <code>oid</code> , will be set. That is,  <code>oid</code> will be set on encrypted bags
whether supported or not. It must be deinitialized using <code>gnutls_free()</code> .
The other variables are only set on supported structures.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_INVALID_REQUEST</code>  if the provided bag isn&rsquo;t encrypted,
<code>GNUTLS_E_UNKNOWN_CIPHER_TYPE</code>  if the structure&rsquo;s encryption isn&rsquo;t supported, or
another negative error code in case of a failure. Zero on success.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fencrypt-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_encrypt</h4>
<a name="gnutls_005fpkcs12_005fbag_005fencrypt"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fencrypt"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_encrypt</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, const char * <var>pass</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>pass</var>: The password used for encryption, must be ASCII
</p>
<p><var>flags</var>: should be one of <code>gnutls_pkcs_encrypt_flags_t</code>  elements bitwise or&rsquo;d
</p>
<p>This function will encrypt the given bag.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
otherwise a negative error code is returned.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fget_005fcount-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_get_count</h4>
<a name="gnutls_005fpkcs12_005fbag_005fget_005fcount"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fget_005fcount"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_get_count</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p>This function will return the number of the elements withing the bag.
</p>
<p><strong>Returns:</strong> Number of elements in bag, or an negative error code on
error.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fget_005fdata-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_get_data</h4>
<a name="gnutls_005fpkcs12_005fbag_005fget_005fdata"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fget_005fdata"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_get_data</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, int <var>indx</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>indx</var>: The element of the bag to get the data from
</p>
<p><var>data</var>: where the bag&rsquo;s data will be. Should be treated as constant.
</p>
<p>This function will return the bag&rsquo;s data. The data is a constant
that is stored into the bag.  Should not be accessed after the bag
is deleted.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fget_005ffriendly_005fname-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_get_friendly_name</h4>
<a name="gnutls_005fpkcs12_005fbag_005fget_005ffriendly_005fname"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fget_005ffriendly_005fname"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_get_friendly_name</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, int <var>indx</var>, char ** <var>name</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>indx</var>: The bag&rsquo;s element to add the id
</p>
<p><var>name</var>: will hold a pointer to the name (to be treated as const)
</p>
<p>This function will return the friendly name, of the specified bag
element.  The key ID is usually used to distinguish the local
private key and the certificate pair.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fget_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_get_key_id</h4>
<a name="gnutls_005fpkcs12_005fbag_005fget_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fget_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_get_key_id</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, int <var>indx</var>, gnutls_datum_t * <var>id</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>indx</var>: The bag&rsquo;s element to add the id
</p>
<p><var>id</var>: where the ID will be copied (to be treated as const)
</p>
<p>This function will return the key ID, of the specified bag element.
The key ID is usually used to distinguish the local private key and
the certificate pair.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fget_005ftype-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_get_type</h4>
<a name="gnutls_005fpkcs12_005fbag_005fget_005ftype"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fget_005ftype"></a>Function: <em>gnutls_pkcs12_bag_type_t</em> <strong>gnutls_pkcs12_bag_get_type</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, int <var>indx</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>indx</var>: The element of the bag to get the type
</p>
<p>This function will return the bag&rsquo;s type.
</p>
<p><strong>Returns:</strong> One of the <code>gnutls_pkcs12_bag_type_t</code>  enumerations.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005finit-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_init</h4>
<a name="gnutls_005fpkcs12_005fbag_005finit"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005finit"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_init</strong> <em>(gnutls_pkcs12_bag_t * <var>bag</var>)</em></dt>
<dd><p><var>bag</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize a PKCS12 bag structure. PKCS12 Bags
usually contain private keys, lists of X.509 Certificates and X.509
Certificate revocation lists.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fset_005fcrl-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_set_crl</h4>
<a name="gnutls_005fpkcs12_005fbag_005fset_005fcrl"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fset_005fcrl"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_set_crl</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, gnutls_x509_crl_t <var>crl</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>crl</var>: the CRL to be copied.
</p>
<p>This function will insert the given CRL into the
bag. This is just a wrapper over <code>gnutls_pkcs12_bag_set_data()</code> .
</p>
<p><strong>Returns:</strong> the index of the added bag on success, or a negative error code
on failure.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fset_005fcrt-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_set_crt</h4>
<a name="gnutls_005fpkcs12_005fbag_005fset_005fcrt"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fset_005fcrt"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_set_crt</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, gnutls_x509_crt_t <var>crt</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>crt</var>: the certificate to be copied.
</p>
<p>This function will insert the given certificate into the
bag. This is just a wrapper over <code>gnutls_pkcs12_bag_set_data()</code> .
</p>
<p><strong>Returns:</strong> the index of the added bag on success, or a negative
value on failure.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fset_005fdata-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_set_data</h4>
<a name="gnutls_005fpkcs12_005fbag_005fset_005fdata"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fset_005fdata"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_set_data</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, gnutls_pkcs12_bag_type_t <var>type</var>, const gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>type</var>: The data&rsquo;s type
</p>
<p><var>data</var>: the data to be copied.
</p>
<p>This function will insert the given data of the given type into
the bag.
</p>
<p><strong>Returns:</strong> the index of the added bag on success, or a negative
value on error.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fset_005ffriendly_005fname-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_set_friendly_name</h4>
<a name="gnutls_005fpkcs12_005fbag_005fset_005ffriendly_005fname"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fset_005ffriendly_005fname"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_set_friendly_name</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, int <var>indx</var>, const char * <var>name</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>indx</var>: The bag&rsquo;s element to add the id
</p>
<p><var>name</var>: the name
</p>
<p>This function will add the given key friendly name, to the
specified, by the index, bag element. The name will be encoded as
a &rsquo;Friendly name&rsquo; bag attribute, which is usually used to set a
user name to the local private key and the certificate pair.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fset_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_set_key_id</h4>
<a name="gnutls_005fpkcs12_005fbag_005fset_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fset_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_set_key_id</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, int <var>indx</var>, const gnutls_datum_t * <var>id</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>indx</var>: The bag&rsquo;s element to add the id
</p>
<p><var>id</var>: the ID
</p>
<p>This function will add the given key ID, to the specified, by the
index, bag element. The key ID will be encoded as a &rsquo;Local key
identifier&rsquo; bag attribute, which is usually used to distinguish
the local private key and the certificate pair.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value. or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fbag_005fset_005fprivkey-1"></a>
<h4 class="subheading">gnutls_pkcs12_bag_set_privkey</h4>
<a name="gnutls_005fpkcs12_005fbag_005fset_005fprivkey"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fbag_005fset_005fprivkey"></a>Function: <em>int</em> <strong>gnutls_pkcs12_bag_set_privkey</strong> <em>(gnutls_pkcs12_bag_t <var>bag</var>, gnutls_x509_privkey_t <var>privkey</var>, const char * <var>password</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>bag</var>: The bag
</p>
<p><var>privkey</var>: the private key to be copied.
</p>
<p><var>password</var>: the password to protect the key with (may be <code>NULL</code> )
</p>
<p><var>flags</var>: should be one of <code>gnutls_pkcs_encrypt_flags_t</code>  elements bitwise or&rsquo;d
</p>
<p>This function will insert the given private key into the
bag. This is just a wrapper over <code>gnutls_pkcs12_bag_set_data()</code> .
</p>
<p><strong>Returns:</strong> the index of the added bag on success, or a negative
value on failure.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fdeinit-1"></a>
<h4 class="subheading">gnutls_pkcs12_deinit</h4>
<a name="gnutls_005fpkcs12_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_pkcs12_deinit</strong> <em>(gnutls_pkcs12_t <var>pkcs12</var>)</em></dt>
<dd><p><var>pkcs12</var>: The type to be initialized
</p>
<p>This function will deinitialize a PKCS12 type.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fexport-1"></a>
<h4 class="subheading">gnutls_pkcs12_export</h4>
<a name="gnutls_005fpkcs12_005fexport"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fexport"></a>Function: <em>int</em> <strong>gnutls_pkcs12_export</strong> <em>(gnutls_pkcs12_t <var>pkcs12</var>, gnutls_x509_crt_fmt_t <var>format</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>pkcs12</var>: A pkcs12 type
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>output_data</var>: will contain a structure PEM or DER encoded
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will export the pkcs12 structure to DER or PEM format.
</p>
<p>If the buffer provided is not long enough to hold the output, then
*output_data_size will be updated and GNUTLS_E_SHORT_MEMORY_BUFFER
will be returned.
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN PKCS12&quot;.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fexport2-1"></a>
<h4 class="subheading">gnutls_pkcs12_export2</h4>
<a name="gnutls_005fpkcs12_005fexport2"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fexport2"></a>Function: <em>int</em> <strong>gnutls_pkcs12_export2</strong> <em>(gnutls_pkcs12_t <var>pkcs12</var>, gnutls_x509_crt_fmt_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>pkcs12</var>: A pkcs12 type
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>out</var>: will contain a structure PEM or DER encoded
</p>
<p>This function will export the pkcs12 structure to DER or PEM format.
</p>
<p>The output buffer is allocated using <code>gnutls_malloc()</code> .
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN PKCS12&quot;.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fgenerate_005fmac-1"></a>
<h4 class="subheading">gnutls_pkcs12_generate_mac</h4>
<a name="gnutls_005fpkcs12_005fgenerate_005fmac"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fgenerate_005fmac"></a>Function: <em>int</em> <strong>gnutls_pkcs12_generate_mac</strong> <em>(gnutls_pkcs12_t <var>pkcs12</var>, const char * <var>pass</var>)</em></dt>
<dd><p><var>pkcs12</var>: A pkcs12 type
</p>
<p><var>pass</var>: The password for the MAC
</p>
<p>This function will generate a MAC for the PKCS12 structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fgenerate_005fmac2-1"></a>
<h4 class="subheading">gnutls_pkcs12_generate_mac2</h4>
<a name="gnutls_005fpkcs12_005fgenerate_005fmac2"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fgenerate_005fmac2"></a>Function: <em>int</em> <strong>gnutls_pkcs12_generate_mac2</strong> <em>(gnutls_pkcs12_t <var>pkcs12</var>, gnutls_mac_algorithm_t <var>mac</var>, const char * <var>pass</var>)</em></dt>
<dd><p><var>pkcs12</var>: A pkcs12 type
</p>
<p><var>mac</var>: the MAC algorithm to use
</p>
<p><var>pass</var>: The password for the MAC
</p>
<p>This function will generate a MAC for the PKCS12 structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fget_005fbag-1"></a>
<h4 class="subheading">gnutls_pkcs12_get_bag</h4>
<a name="gnutls_005fpkcs12_005fget_005fbag"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fget_005fbag"></a>Function: <em>int</em> <strong>gnutls_pkcs12_get_bag</strong> <em>(gnutls_pkcs12_t <var>pkcs12</var>, int <var>indx</var>, gnutls_pkcs12_bag_t <var>bag</var>)</em></dt>
<dd><p><var>pkcs12</var>: A pkcs12 type
</p>
<p><var>indx</var>: contains the index of the bag to extract
</p>
<p><var>bag</var>: An initialized bag, where the contents of the bag will be copied
</p>
<p>This function will return a Bag from the PKCS12 structure.
</p>
<p>After the last Bag has been read
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  will be returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fimport-1"></a>
<h4 class="subheading">gnutls_pkcs12_import</h4>
<a name="gnutls_005fpkcs12_005fimport"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fimport"></a>Function: <em>int</em> <strong>gnutls_pkcs12_import</strong> <em>(gnutls_pkcs12_t <var>pkcs12</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkcs12</var>: The data to store the parsed PKCS12.
</p>
<p><var>data</var>: The DER or PEM encoded PKCS12.
</p>
<p><var>format</var>: One of DER or PEM
</p>
<p><var>flags</var>: an ORed sequence of gnutls_privkey_pkcs8_flags
</p>
<p>This function will convert the given DER or PEM encoded PKCS12
to the native gnutls_pkcs12_t format. The output will be stored in &rsquo;pkcs12&rsquo;.
</p>
<p>If the PKCS12 is PEM encoded it should have a header of &quot;PKCS12&quot;.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005finit-1"></a>
<h4 class="subheading">gnutls_pkcs12_init</h4>
<a name="gnutls_005fpkcs12_005finit"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005finit"></a>Function: <em>int</em> <strong>gnutls_pkcs12_init</strong> <em>(gnutls_pkcs12_t * <var>pkcs12</var>)</em></dt>
<dd><p><var>pkcs12</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize a PKCS12 type. PKCS12 structures
usually contain lists of X.509 Certificates and X.509 Certificate
revocation lists.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fmac_005finfo-1"></a>
<h4 class="subheading">gnutls_pkcs12_mac_info</h4>
<a name="gnutls_005fpkcs12_005fmac_005finfo"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fmac_005finfo"></a>Function: <em>int</em> <strong>gnutls_pkcs12_mac_info</strong> <em>(gnutls_pkcs12_t <var>pkcs12</var>, unsigned int * <var>mac</var>, void * <var>salt</var>, unsigned int * <var>salt_size</var>, unsigned int * <var>iter_count</var>, char ** <var>oid</var>)</em></dt>
<dd><p><var>pkcs12</var>: A pkcs12 type
</p>
<p><var>mac</var>: the MAC algorithm used as <code>gnutls_mac_algorithm_t</code> 
</p>
<p><var>salt</var>: the salt used for string to key (if non-NULL then  <code>salt_size</code> initially holds its size)
</p>
<p><var>salt_size</var>: string to key salt size
</p>
<p><var>iter_count</var>: string to key iteration count
</p>
<p><var>oid</var>: if non-NULL it will contain an allocated null-terminated variable with the OID
</p>
<p>This function will provide information on the MAC algorithm used
in a PKCS <code>12</code>  structure. If the structure algorithms
are unknown the code <code>GNUTLS_E_UNKNOWN_HASH_ALGORITHM</code>  will be returned,
and only  <code>oid</code> , will be set. That is,  <code>oid</code> will be set on structures
with a MAC whether supported or not. It must be deinitialized using <code>gnutls_free()</code> .
The other variables are only set on supported structures.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_INVALID_REQUEST</code>  if the provided structure doesn&rsquo;t contain a MAC,
<code>GNUTLS_E_UNKNOWN_HASH_ALGORITHM</code>  if the structure&rsquo;s MAC isn&rsquo;t supported, or
another negative error code in case of a failure. Zero on success.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fset_005fbag-1"></a>
<h4 class="subheading">gnutls_pkcs12_set_bag</h4>
<a name="gnutls_005fpkcs12_005fset_005fbag"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fset_005fbag"></a>Function: <em>int</em> <strong>gnutls_pkcs12_set_bag</strong> <em>(gnutls_pkcs12_t <var>pkcs12</var>, gnutls_pkcs12_bag_t <var>bag</var>)</em></dt>
<dd><p><var>pkcs12</var>: should contain a gnutls_pkcs12_t type
</p>
<p><var>bag</var>: An initialized bag
</p>
<p>This function will insert a Bag into the PKCS12 structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fsimple_005fparse-1"></a>
<h4 class="subheading">gnutls_pkcs12_simple_parse</h4>
<a name="gnutls_005fpkcs12_005fsimple_005fparse"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fsimple_005fparse-1"></a>Function: <em>int</em> <strong>gnutls_pkcs12_simple_parse</strong> <em>(gnutls_pkcs12_t <var>p12</var>, const char * <var>password</var>, gnutls_x509_privkey_t * <var>key</var>, gnutls_x509_crt_t ** <var>chain</var>, unsigned int * <var>chain_len</var>, gnutls_x509_crt_t ** <var>extra_certs</var>, unsigned int * <var>extra_certs_len</var>, gnutls_x509_crl_t * <var>crl</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>p12</var>: A pkcs12 type
</p>
<p><var>password</var>: optional password used to decrypt the structure, bags and keys.
</p>
<p><var>key</var>: a structure to store the parsed private key.
</p>
<p><var>chain</var>: the corresponding to key certificate chain (may be <code>NULL</code> )
</p>
<p><var>chain_len</var>: will be updated with the number of additional (may be <code>NULL</code> )
</p>
<p><var>extra_certs</var>: optional pointer to receive an array of additional
certificates found in the PKCS12 structure (may be <code>NULL</code> ).
</p>
<p><var>extra_certs_len</var>: will be updated with the number of additional
certs (may be <code>NULL</code> ).
</p>
<p><var>crl</var>: an optional structure to store the parsed CRL (may be <code>NULL</code> ).
</p>
<p><var>flags</var>: should be zero or one of GNUTLS_PKCS12_SP_*
</p>
<p>This function parses a PKCS12 structure in  <code>pkcs12</code> and extracts the
private key, the corresponding certificate chain, any additional
certificates and a CRL.
</p>
<p>The  <code>extra_certs</code> and  <code>extra_certs_len</code> parameters are optional
and both may be set to <code>NULL</code> . If either is non-<code>NULL</code> , then both must
be set. The value for  <code>extra_certs</code> is allocated
using <code>gnutls_malloc()</code> .
</p>
<p>Encrypted PKCS12 bags and PKCS8 private keys are supported, but
only with password based security and the same password for all
operations.
</p>
<p>Note that a PKCS12 structure may contain many keys and/or certificates,
and there is no way to identify which key/certificate pair you want.
For this reason this function is useful for PKCS12 files that contain 
only one key/certificate pair and/or one CRL.
</p>
<p>If the provided structure has encrypted fields but no password
is provided then this function returns <code>GNUTLS_E_DECRYPTION_FAILED</code> .
</p>
<p>Note that normally the chain constructed does not include self signed
certificates, to comply with TLS&rsquo; requirements. If, however, the flag 
<code>GNUTLS_PKCS12_SP_INCLUDE_SELF_SIGNED</code>  is specified then
self signed certificates will be included in the chain.
</p>
<p>Prior to using this function the PKCS <code>12</code>  structure integrity must
be verified using <code>gnutls_pkcs12_verify_mac()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fpkcs12_005fverify_005fmac-1"></a>
<h4 class="subheading">gnutls_pkcs12_verify_mac</h4>
<a name="gnutls_005fpkcs12_005fverify_005fmac"></a><dl>
<dt><a name="index-gnutls_005fpkcs12_005fverify_005fmac"></a>Function: <em>int</em> <strong>gnutls_pkcs12_verify_mac</strong> <em>(gnutls_pkcs12_t <var>pkcs12</var>, const char * <var>pass</var>)</em></dt>
<dd><p><var>pkcs12</var>: should contain a gnutls_pkcs12_t type
</p>
<p><var>pass</var>: The password for the MAC
</p>
<p>This function will verify the MAC for the PKCS12 structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>


<hr>
<a name="PKCS-11-API"></a>
<div class="header">
<p>
Next: <a href="#TPM-API" accesskey="n" rel="next">TPM API</a>, Previous: <a href="#PKCS-12-API" accesskey="p" rel="prev">PKCS 12 API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Hardware-token-via-PKCS-11-API"></a>
<h3 class="section">E.8 Hardware token via PKCS 11 API</h3>

<p>The following functions are to be used for PKCS 11 handling.
Their prototypes lie in <samp>gnutls/pkcs11.h</samp>.
</p>

<a name="gnutls_005fpkcs11_005fadd_005fprovider-1"></a>
<h4 class="subheading">gnutls_pkcs11_add_provider</h4>
<a name="gnutls_005fpkcs11_005fadd_005fprovider"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fadd_005fprovider"></a>Function: <em>int</em> <strong>gnutls_pkcs11_add_provider</strong> <em>(const char * <var>name</var>, const char * <var>params</var>)</em></dt>
<dd><p><var>name</var>: The filename of the module
</p>
<p><var>params</var>: should be NULL
</p>
<p>This function will load and add a PKCS 11 module to the module
list used in gnutls. After this function is called the module will
be used for PKCS 11 operations.
</p>
<p>When loading a module to be used for certificate verification,
use the string &rsquo;trusted&rsquo; as  <code>params</code> .
</p>
<p>Note that this function is not thread safe.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fcopy_005fattached_005fextension-1"></a>
<h4 class="subheading">gnutls_pkcs11_copy_attached_extension</h4>
<a name="gnutls_005fpkcs11_005fcopy_005fattached_005fextension"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fcopy_005fattached_005fextension"></a>Function: <em>int</em> <strong>gnutls_pkcs11_copy_attached_extension</strong> <em>(const char * <var>token_url</var>, gnutls_x509_crt_t <var>crt</var>, gnutls_datum_t * <var>data</var>, const char * <var>label</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>token_url</var>: A PKCS <code>11</code>  URL specifying a token
</p>
<p><var>crt</var>: An X.509 certificate object
</p>
<p><var>data</var>: the attached extension
</p>
<p><var>label</var>: A name to be used for the attached extension (may be <code>NULL</code> )
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_FLAG_*
</p>
<p>This function will copy an the attached extension in  <code>data</code> for
the certificate provided in  <code>crt</code> in the PKCS <code>11</code>  token specified
by the URL (typically a trust module). The extension must be in
RFC5280 Extension format.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.8
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fcopy_005fpubkey-1"></a>
<h4 class="subheading">gnutls_pkcs11_copy_pubkey</h4>
<a name="gnutls_005fpkcs11_005fcopy_005fpubkey"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fcopy_005fpubkey"></a>Function: <em>int</em> <strong>gnutls_pkcs11_copy_pubkey</strong> <em>(const char * <var>token_url</var>, gnutls_pubkey_t <var>pubkey</var>, const char * <var>label</var>, const gnutls_datum_t * <var>cid</var>, unsigned int <var>key_usage</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>token_url</var>: A PKCS <code>11</code>  URL specifying a token
</p>
<p><var>pubkey</var>: The public key to copy
</p>
<p><var>label</var>: The name to be used for the stored data
</p>
<p><var>cid</var>: The CKA_ID to set for the object -if NULL, the ID will be derived from the public key
</p>
<p><var>key_usage</var>: One of GNUTLS_KEY_*
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_FLAG_*
</p>
<p>This function will copy a public key object into a PKCS <code>11</code>  token specified by
a URL. Valid flags to mark the key: <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_TRUSTED</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_MARK_SENSITIVE</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_PRIVATE</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_MARK_CA</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_ALWAYS_AUTH</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.6
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fcopy_005fsecret_005fkey-1"></a>
<h4 class="subheading">gnutls_pkcs11_copy_secret_key</h4>
<a name="gnutls_005fpkcs11_005fcopy_005fsecret_005fkey"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fcopy_005fsecret_005fkey"></a>Function: <em>int</em> <strong>gnutls_pkcs11_copy_secret_key</strong> <em>(const char * <var>token_url</var>, gnutls_datum_t * <var>key</var>, const char * <var>label</var>, unsigned int <var>key_usage</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>token_url</var>: A PKCS <code>11</code>  URL specifying a token
</p>
<p><var>key</var>: The raw key
</p>
<p><var>label</var>: A name to be used for the stored data
</p>
<p><var>key_usage</var>: One of GNUTLS_KEY_*
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_FLAG_*
</p>
<p>This function will copy a raw secret (symmetric) key into a PKCS <code>11</code>  
token specified by a URL. The key can be marked as sensitive or not.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fcopy_005fx509_005fcrt-1"></a>
<h4 class="subheading">gnutls_pkcs11_copy_x509_crt</h4>
<a name="gnutls_005fpkcs11_005fcopy_005fx509_005fcrt"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fcopy_005fx509_005fcrt"></a>Function: <em>int</em> <strong>gnutls_pkcs11_copy_x509_crt</strong> <em>(const char * <var>token_url</var>, gnutls_x509_crt_t <var>crt</var>, const char * <var>label</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>token_url</var>: A PKCS <code>11</code>  URL specifying a token
</p>
<p><var>crt</var>: A certificate
</p>
<p><var>label</var>: A name to be used for the stored data
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_FLAG_*
</p>
<p>This function will copy a certificate into a PKCS <code>11</code>  token specified by
a URL. The certificate can be marked as trusted or not.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fcopy_005fx509_005fcrt2-1"></a>
<h4 class="subheading">gnutls_pkcs11_copy_x509_crt2</h4>
<a name="gnutls_005fpkcs11_005fcopy_005fx509_005fcrt2"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fcopy_005fx509_005fcrt2-1"></a>Function: <em>int</em> <strong>gnutls_pkcs11_copy_x509_crt2</strong> <em>(const char * <var>token_url</var>, gnutls_x509_crt_t <var>crt</var>, const char * <var>label</var>, const gnutls_datum_t * <var>cid</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>token_url</var>: A PKCS <code>11</code>  URL specifying a token
</p>
<p><var>crt</var>: The certificate to copy
</p>
<p><var>label</var>: The name to be used for the stored data
</p>
<p><var>cid</var>: The CKA_ID to set for the object -if NULL, the ID will be derived from the public key
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_FLAG_*
</p>
<p>This function will copy a certificate into a PKCS <code>11</code>  token specified by
a URL. Valid flags to mark the certificate: <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_TRUSTED</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_MARK_SENSITIVE</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_PRIVATE</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_MARK_CA</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_ALWAYS_AUTH</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fcopy_005fx509_005fprivkey-1"></a>
<h4 class="subheading">gnutls_pkcs11_copy_x509_privkey</h4>
<a name="gnutls_005fpkcs11_005fcopy_005fx509_005fprivkey"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fcopy_005fx509_005fprivkey"></a>Function: <em>int</em> <strong>gnutls_pkcs11_copy_x509_privkey</strong> <em>(const char * <var>token_url</var>, gnutls_x509_privkey_t <var>key</var>, const char * <var>label</var>, unsigned int <var>key_usage</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>token_url</var>: A PKCS <code>11</code>  URL specifying a token
</p>
<p><var>key</var>: A private key
</p>
<p><var>label</var>: A name to be used for the stored data
</p>
<p><var>key_usage</var>: One of GNUTLS_KEY_*
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_* flags
</p>
<p>This function will copy a private key into a PKCS <code>11</code>  token specified by
a URL. It is highly recommended flags to contain <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_SENSITIVE</code> 
unless there is a strong reason not to.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fcopy_005fx509_005fprivkey2-1"></a>
<h4 class="subheading">gnutls_pkcs11_copy_x509_privkey2</h4>
<a name="gnutls_005fpkcs11_005fcopy_005fx509_005fprivkey2"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fcopy_005fx509_005fprivkey2-1"></a>Function: <em>int</em> <strong>gnutls_pkcs11_copy_x509_privkey2</strong> <em>(const char * <var>token_url</var>, gnutls_x509_privkey_t <var>key</var>, const char * <var>label</var>, const gnutls_datum_t * <var>cid</var>, unsigned int <var>key_usage</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>token_url</var>: A PKCS <code>11</code>  URL specifying a token
</p>
<p><var>key</var>: A private key
</p>
<p><var>label</var>: A name to be used for the stored data
</p>
<p><var>cid</var>: The CKA_ID to set for the object -if NULL, the ID will be derived from the public key
</p>
<p><var>key_usage</var>: One of GNUTLS_KEY_*
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_* flags
</p>
<p>This function will copy a private key into a PKCS <code>11</code>  token specified by
a URL. It is highly recommended flags to contain <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_SENSITIVE</code> 
unless there is a strong reason not to.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fcrt_005fis_005fknown-1"></a>
<h4 class="subheading">gnutls_pkcs11_crt_is_known</h4>
<a name="gnutls_005fpkcs11_005fcrt_005fis_005fknown"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fcrt_005fis_005fknown"></a>Function: <em>int</em> <strong>gnutls_pkcs11_crt_is_known</strong> <em>(const char * <var>url</var>, gnutls_x509_crt_t <var>cert</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>url</var>: A PKCS 11 url identifying a token
</p>
<p><var>cert</var>: is the certificate to find issuer for
</p>
<p><var>flags</var>: Use zero or flags from <code>GNUTLS_PKCS11_OBJ_FLAG</code> .
</p>
<p>This function will check whether the provided certificate is stored
in the specified token. This is useful in combination with 
<code>GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_TRUSTED</code>  or
<code>GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_DISTRUSTED</code> ,
to check whether a CA is present or a certificate is blacklisted in
a trust PKCS <code>11</code>  module.
</p>
<p>This function can be used with a  <code>url</code> of &quot;pkcs11:&quot;, and in that case all modules
will be searched. To restrict the modules to the marked as trusted in p11-kit
use the <code>GNUTLS_PKCS11_OBJ_FLAG_PRESENT_IN_TRUSTED_MODULE</code>  flag.
</p>
<p>Note that the flag <code>GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_DISTRUSTED</code>  is
specific to p11-kit trust modules.
</p>
<p><strong>Returns:</strong> If the certificate exists non-zero is returned, otherwise zero.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fdeinit-1"></a>
<h4 class="subheading">gnutls_pkcs11_deinit</h4>
<a name="gnutls_005fpkcs11_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_pkcs11_deinit</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>This function will deinitialize the PKCS 11 subsystem in gnutls.
This function is only needed if you need to deinitialize the
subsystem without calling <code>gnutls_global_deinit()</code> .
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fdelete_005furl-1"></a>
<h4 class="subheading">gnutls_pkcs11_delete_url</h4>
<a name="gnutls_005fpkcs11_005fdelete_005furl"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fdelete_005furl-1"></a>Function: <em>int</em> <strong>gnutls_pkcs11_delete_url</strong> <em>(const char * <var>object_url</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>object_url</var>: The URL of the object to delete.
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_* flags
</p>
<p>This function will delete objects matching the given URL.
Note that not all tokens support the delete operation.
</p>
<p><strong>Returns:</strong> On success, the number of objects deleted is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fget_005fpin_005ffunction-1"></a>
<h4 class="subheading">gnutls_pkcs11_get_pin_function</h4>
<a name="gnutls_005fpkcs11_005fget_005fpin_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fget_005fpin_005ffunction"></a>Function: <em>gnutls_pin_callback_t</em> <strong>gnutls_pkcs11_get_pin_function</strong> <em>(void ** <var>userdata</var>)</em></dt>
<dd><p><var>userdata</var>: data to be supplied to callback
</p>
<p>This function will return the callback function set using
<code>gnutls_pkcs11_set_pin_function()</code> .
</p>
<p><strong>Returns:</strong> The function set or NULL otherwise.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fget_005fraw_005fissuer-1"></a>
<h4 class="subheading">gnutls_pkcs11_get_raw_issuer</h4>
<a name="gnutls_005fpkcs11_005fget_005fraw_005fissuer"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fget_005fraw_005fissuer"></a>Function: <em>int</em> <strong>gnutls_pkcs11_get_raw_issuer</strong> <em>(const char * <var>url</var>, gnutls_x509_crt_t <var>cert</var>, gnutls_datum_t * <var>issuer</var>, gnutls_x509_crt_fmt_t <var>fmt</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>url</var>: A PKCS 11 url identifying a token
</p>
<p><var>cert</var>: is the certificate to find issuer for
</p>
<p><var>issuer</var>: Will hold the issuer if any in an allocated buffer.
</p>
<p><var>fmt</var>: The format of the exported issuer.
</p>
<p><var>flags</var>: Use zero or flags from <code>GNUTLS_PKCS11_OBJ_FLAG</code> .
</p>
<p>This function will return the issuer of a given certificate, if it
is stored in the token. By default only marked as trusted issuers
are retuned. If any issuer should be returned specify
<code>GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_ANY</code>  in  <code>flags</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.2.7
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fget_005fraw_005fissuer_005fby_005fdn-1"></a>
<h4 class="subheading">gnutls_pkcs11_get_raw_issuer_by_dn</h4>
<a name="gnutls_005fpkcs11_005fget_005fraw_005fissuer_005fby_005fdn"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fget_005fraw_005fissuer_005fby_005fdn"></a>Function: <em>int</em> <strong>gnutls_pkcs11_get_raw_issuer_by_dn</strong> <em>(const char * <var>url</var>, const gnutls_datum_t * <var>dn</var>, gnutls_datum_t * <var>issuer</var>, gnutls_x509_crt_fmt_t <var>fmt</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>url</var>: A PKCS 11 url identifying a token
</p>
<p><var>dn</var>: is the DN to search for
</p>
<p><var>issuer</var>: Will hold the issuer if any in an allocated buffer.
</p>
<p><var>fmt</var>: The format of the exported issuer.
</p>
<p><var>flags</var>: Use zero or flags from <code>GNUTLS_PKCS11_OBJ_FLAG</code> .
</p>
<p>This function will return the certificate with the given DN, if it
is stored in the token. By default only marked as trusted issuers
are retuned. If any issuer should be returned specify
<code>GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_ANY</code>  in  <code>flags</code> .
</p>
<p>The name of the function includes issuer because it can
be used to discover issuers of certificates.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fget_005fraw_005fissuer_005fby_005fsubject_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_pkcs11_get_raw_issuer_by_subject_key_id</h4>
<a name="gnutls_005fpkcs11_005fget_005fraw_005fissuer_005fby_005fsubject_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fget_005fraw_005fissuer_005fby_005fsubject_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_pkcs11_get_raw_issuer_by_subject_key_id</strong> <em>(const char * <var>url</var>, const gnutls_datum_t * <var>dn</var>, const gnutls_datum_t * <var>spki</var>, gnutls_datum_t * <var>issuer</var>, gnutls_x509_crt_fmt_t <var>fmt</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>url</var>: A PKCS 11 url identifying a token
</p>
<p><var>dn</var>: is the DN to search for (may be <code>NULL</code> )
</p>
<p><var>spki</var>: is the subject key ID to search for
</p>
<p><var>issuer</var>: Will hold the issuer if any in an allocated buffer.
</p>
<p><var>fmt</var>: The format of the exported issuer.
</p>
<p><var>flags</var>: Use zero or flags from <code>GNUTLS_PKCS11_OBJ_FLAG</code> .
</p>
<p>This function will return the certificate with the given DN and  <code>spki</code> , if it
is stored in the token. By default only marked as trusted issuers
are retuned. If any issuer should be returned specify
<code>GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_ANY</code>  in  <code>flags</code> .
</p>
<p>The name of the function includes issuer because it can
be used to discover issuers of certificates.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.2
</p></dd></dl>

<a name="gnutls_005fpkcs11_005finit-1"></a>
<h4 class="subheading">gnutls_pkcs11_init</h4>
<a name="gnutls_005fpkcs11_005finit"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005finit-1"></a>Function: <em>int</em> <strong>gnutls_pkcs11_init</strong> <em>(unsigned int <var>flags</var>, const char * <var>deprecated_config_file</var>)</em></dt>
<dd><p><var>flags</var>: An ORed sequence of <code>GNUTLS_PKCS11_FLAG_</code> *
</p>
<p><var>deprecated_config_file</var>: either NULL or the location of a deprecated
configuration file
</p>
<p>This function will initialize the PKCS 11 subsystem in gnutls. It will
read configuration files if <code>GNUTLS_PKCS11_FLAG_AUTO</code>  is used or allow
you to independently load PKCS 11 modules using <code>gnutls_pkcs11_add_provider()</code> 
if <code>GNUTLS_PKCS11_FLAG_MANUAL</code>  is specified.
</p>
<p>You don&rsquo;t need to call this function since GnuTLS 3.3.0 because it is being called
during the first request PKCS 11 operation. That call will assume the <code>GNUTLS_PKCS11_FLAG_AUTO</code> 
flag. If another flags are required then it must be called independently
prior to any PKCS 11 operation.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fdeinit-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_deinit</h4>
<a name="gnutls_005fpkcs11_005fobj_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_pkcs11_obj_deinit</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>)</em></dt>
<dd><p><var>obj</var>: The type to be deinitialized
</p>
<p>This function will deinitialize a certificate structure.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fexport-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_export</h4>
<a name="gnutls_005fpkcs11_005fobj_005fexport"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fexport"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_export</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>obj</var>: Holds the object
</p>
<p><var>output_data</var>: will contain the object data
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will export the PKCS11 object data.  It is normal for
data to be inaccesible and in that case <code>GNUTLS_E_INVALID_REQUEST</code> 
will be returned.
</p>
<p>If the buffer provided is not long enough to hold the output, then
*output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
be returned.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and <code>GNUTLS_E_SUCCESS</code>  (0) on success.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fexport2-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_export2</h4>
<a name="gnutls_005fpkcs11_005fobj_005fexport2"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fexport2"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_export2</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>obj</var>: Holds the object
</p>
<p><var>out</var>: will contain the object data
</p>
<p>This function will export the PKCS11 object data.  It is normal for
data to be inaccesible and in that case <code>GNUTLS_E_INVALID_REQUEST</code> 
will be returned.
</p>
<p>The output buffer is allocated using <code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and <code>GNUTLS_E_SUCCESS</code>  (0) on success.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fexport3-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_export3</h4>
<a name="gnutls_005fpkcs11_005fobj_005fexport3"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fexport3"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_export3</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>, gnutls_x509_crt_fmt_t <var>fmt</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>obj</var>: Holds the object
</p>
<p><var>fmt</var>: The format of the exported data
</p>
<p><var>out</var>: will contain the object data
</p>
<p>This function will export the PKCS11 object data.  It is normal for
data to be inaccesible and in that case <code>GNUTLS_E_INVALID_REQUEST</code> 
will be returned.
</p>
<p>The output buffer is allocated using <code>gnutls_malloc()</code> .
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and <code>GNUTLS_E_SUCCESS</code>  (0) on success.
</p>
<p><strong>Since:</strong> 3.2.7
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fexport_005furl-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_export_url</h4>
<a name="gnutls_005fpkcs11_005fobj_005fexport_005furl"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fexport_005furl"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_export_url</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>, gnutls_pkcs11_url_type_t <var>detailed</var>, char ** <var>url</var>)</em></dt>
<dd><p><var>obj</var>: Holds the PKCS 11 certificate
</p>
<p><var>detailed</var>: non zero if a detailed URL is required
</p>
<p><var>url</var>: will contain an allocated url
</p>
<p>This function will export a URL identifying the given certificate.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fflags_005fget_005fstr-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_flags_get_str</h4>
<a name="gnutls_005fpkcs11_005fobj_005fflags_005fget_005fstr"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fflags_005fget_005fstr"></a>Function: <em>char *</em> <strong>gnutls_pkcs11_obj_flags_get_str</strong> <em>(unsigned int <var>flags</var>)</em></dt>
<dd><p><var>flags</var>: holds the flags
</p>
<p>This function given an or-sequence of <code>GNUTLS_PKCS11_OBJ_FLAG_MARK</code> ,
will return an allocated string with its description. The string
needs to be deallocated using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> If flags is zero <code>NULL</code>  is returned, otherwise an allocated string.
</p>
<p><strong>Since:</strong> 3.3.7
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fget_005fexts-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_get_exts</h4>
<a name="gnutls_005fpkcs11_005fobj_005fget_005fexts"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fget_005fexts"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_get_exts</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>, gnutls_x509_ext_st ** <var>exts</var>, unsigned int * <var>exts_size</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>obj</var>: should contain a <code>gnutls_pkcs11_obj_t</code>  type
</p>
<p><var>exts</var>: an allocated list of pointers to <code>gnutls_x509_ext_st</code> 
</p>
<p><var>exts_size</var>: the number of  <code>exts</code> 
</p>
<p><var>flags</var>: Or sequence of <code>GNUTLS_PKCS11_OBJ_</code> * flags 
</p>
<p>This function will return information about attached extensions
that associate to the provided object (which should be a certificate).
The extensions are the attached p11-kit trust module extensions.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success or a negative error code on error.
</p>
<p><strong>Since:</strong> 3.3.8
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fget_005fflags-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_get_flags</h4>
<a name="gnutls_005fpkcs11_005fobj_005fget_005fflags"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fget_005fflags"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_get_flags</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>, unsigned int * <var>oflags</var>)</em></dt>
<dd><p><var>obj</var>: The pkcs11 object
</p>
<p><var>oflags</var>: Will hold the output flags
</p>
<p>This function will return the flags of the object.
The  <code>oflags</code> will be flags from <code>gnutls_pkcs11_obj_flags</code> . That is,
the <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_</code> * flags.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.7
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fget_005finfo-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_get_info</h4>
<a name="gnutls_005fpkcs11_005fobj_005fget_005finfo"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fget_005finfo-1"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_get_info</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>, gnutls_pkcs11_obj_info_t <var>itype</var>, void * <var>output</var>, size_t * <var>output_size</var>)</em></dt>
<dd><p><var>obj</var>: should contain a <code>gnutls_pkcs11_obj_t</code>  type
</p>
<p><var>itype</var>: Denotes the type of information requested
</p>
<p><var>output</var>: where output will be stored
</p>
<p><var>output_size</var>: contains the maximum size of the output and will be overwritten with actual
</p>
<p>This function will return information about the PKCS11 certificate
such as the label, id as well as token information where the key is
stored. When output is text it returns null terminated string
although  <code>output_size</code> contains the size of the actual data only.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fget_005ftype-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_get_type</h4>
<a name="gnutls_005fpkcs11_005fobj_005fget_005ftype"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fget_005ftype"></a>Function: <em>gnutls_pkcs11_obj_type_t</em> <strong>gnutls_pkcs11_obj_get_type</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>)</em></dt>
<dd><p><var>obj</var>: Holds the PKCS 11 object
</p>
<p>This function will return the type of the object being
stored in the structure.
</p>
<p><strong>Returns:</strong> The type of the object
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fimport_005furl-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_import_url</h4>
<a name="gnutls_005fpkcs11_005fobj_005fimport_005furl"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fimport_005furl"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_import_url</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>, const char * <var>url</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>obj</var>: The structure to store the object
</p>
<p><var>url</var>: a PKCS 11 url identifying the key
</p>
<p><var>flags</var>: Or sequence of GNUTLS_PKCS11_OBJ_* flags
</p>
<p>This function will &quot;import&quot; a PKCS 11 URL identifying an object (e.g. certificate)
to the <code>gnutls_pkcs11_obj_t</code>  type. This does not involve any
parsing (such as X.509 or OpenPGP) since the <code>gnutls_pkcs11_obj_t</code>  is
format agnostic. Only data are transferred.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005finit-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_init</h4>
<a name="gnutls_005fpkcs11_005fobj_005finit"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005finit"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_init</strong> <em>(gnutls_pkcs11_obj_t * <var>obj</var>)</em></dt>
<dd><p><var>obj</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize a pkcs11 certificate structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005flist_005fimport_005furl3-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_list_import_url3</h4>
<a name="gnutls_005fpkcs11_005fobj_005flist_005fimport_005furl3"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005flist_005fimport_005furl3"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_list_import_url3</strong> <em>(gnutls_pkcs11_obj_t * <var>p_list</var>, unsigned int * <var>n_list</var>, const char * <var>url</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>p_list</var>: An uninitialized object list (may be NULL)
</p>
<p><var>n_list</var>: initially should hold the maximum size of the list. Will contain the actual size.
</p>
<p><var>url</var>: A PKCS 11 url identifying a set of objects
</p>
<p><var>flags</var>: Or sequence of GNUTLS_PKCS11_OBJ_* flags
</p>
<p>This function will initialize and set values to an object list
by using all objects identified by a PKCS 11 URL.
</p>
<p>The supported in this function  <code>flags</code> are <code>GNUTLS_PKCS11_OBJ_FLAG_LOGIN</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_LOGIN_SO</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_PRESENT_IN_TRUSTED_MODULE</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_CRT</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_PUBKEY</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_PRIVKEY</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_WITH_PRIVKEY</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_CA</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_MARK_TRUSTED</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005flist_005fimport_005furl4-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_list_import_url4</h4>
<a name="gnutls_005fpkcs11_005fobj_005flist_005fimport_005furl4"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005flist_005fimport_005furl4"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_list_import_url4</strong> <em>(gnutls_pkcs11_obj_t ** <var>p_list</var>, unsigned int * <var>n_list</var>, const char * <var>url</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>p_list</var>: An uninitialized object list (may be NULL)
</p>
<p><var>n_list</var>: It will contain the size of the list.
</p>
<p><var>url</var>: A PKCS 11 url identifying a set of objects
</p>
<p><var>flags</var>: Or sequence of GNUTLS_PKCS11_OBJ_* flags
</p>
<p>This function will initialize and set values to an object list
by using all objects identified by the PKCS 11 URL. The output
is stored in  <code>p_list</code> , which will be initialized.
</p>
<p>All returned objects must be deinitialized using <code>gnutls_pkcs11_obj_deinit()</code> ,
and  <code>p_list</code> must be free&rsquo;d using <code>gnutls_free()</code> .
</p>
<p>The supported in this function  <code>flags</code> are <code>GNUTLS_PKCS11_OBJ_FLAG_LOGIN</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_LOGIN_SO</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_PRESENT_IN_TRUSTED_MODULE</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_CRT</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_PUBKEY</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_PRIVKEY</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_WITH_PRIVKEY</code> , <code>GNUTLS_PKCS11_OBJ_FLAG_MARK_CA</code> ,
<code>GNUTLS_PKCS11_OBJ_FLAG_MARK_TRUSTED</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fset_005finfo-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_set_info</h4>
<a name="gnutls_005fpkcs11_005fobj_005fset_005finfo"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fset_005finfo"></a>Function: <em>int</em> <strong>gnutls_pkcs11_obj_set_info</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>, gnutls_pkcs11_obj_info_t <var>itype</var>, const void * <var>data</var>, size_t <var>data_size</var>, unsigned <var>flags</var>)</em></dt>
<dd><p><var>obj</var>: should contain a <code>gnutls_pkcs11_obj_t</code>  type
</p>
<p><var>itype</var>: Denotes the type of information to be set
</p>
<p><var>data</var>: the data to set
</p>
<p><var>data_size</var>: the size of data
</p>
<p><var>flags</var>: Or sequence of GNUTLS_PKCS11_OBJ_* flags
</p>
<p>This function will set attributes on the provided object.
Available options for  <code>itype</code> are <code>GNUTLS_PKCS11_OBJ_LABEL</code> ,
<code>GNUTLS_PKCS11_OBJ_ID_HEX</code> , and <code>GNUTLS_PKCS11_OBJ_ID</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success or a negative error code on error.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fobj_005fset_005fpin_005ffunction-1"></a>
<h4 class="subheading">gnutls_pkcs11_obj_set_pin_function</h4>
<a name="gnutls_005fpkcs11_005fobj_005fset_005fpin_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fobj_005fset_005fpin_005ffunction"></a>Function: <em>void</em> <strong>gnutls_pkcs11_obj_set_pin_function</strong> <em>(gnutls_pkcs11_obj_t <var>obj</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</em></dt>
<dd><p><var>obj</var>: The object structure
</p>
<p><var>fn</var>: the callback
</p>
<p><var>userdata</var>: data associated with the callback
</p>
<p>This function will set a callback function to be used when
required to access the object. This function overrides the global
set using <code>gnutls_pkcs11_set_pin_function()</code> .
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005fcpy-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_cpy</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005fcpy"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005fcpy"></a>Function: <em>int</em> <strong>gnutls_pkcs11_privkey_cpy</strong> <em>(gnutls_pkcs11_privkey_t <var>dst</var>, gnutls_pkcs11_privkey_t <var>src</var>)</em></dt>
<dd><p><var>dst</var>: The destination key, which should be initialized.
</p>
<p><var>src</var>: The source key
</p>
<p>This function will copy a private key from source to destination
key. Destination has to be initialized.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005fdeinit-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_deinit</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_pkcs11_privkey_deinit</strong> <em>(gnutls_pkcs11_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: the key to be deinitialized
</p>
<p>This function will deinitialize a private key structure.
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005fexport_005fpubkey-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_export_pubkey</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005fexport_005fpubkey"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005fexport_005fpubkey"></a>Function: <em>int</em> <strong>gnutls_pkcs11_privkey_export_pubkey</strong> <em>(gnutls_pkcs11_privkey_t <var>pkey</var>, gnutls_x509_crt_fmt_t <var>fmt</var>, gnutls_datum_t * <var>data</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>fmt</var>: the format of output params. PEM or DER.
</p>
<p><var>data</var>: will hold the public key
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will extract the public key (modulus and public
exponent) from the private key specified by the  <code>url</code> private key.
This public key will be stored in  <code>pubkey</code> in the format specified
by  <code>fmt</code> .  <code>pubkey</code> should be deinitialized using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.7
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005fexport_005furl-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_export_url</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005fexport_005furl"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005fexport_005furl"></a>Function: <em>int</em> <strong>gnutls_pkcs11_privkey_export_url</strong> <em>(gnutls_pkcs11_privkey_t <var>key</var>, gnutls_pkcs11_url_type_t <var>detailed</var>, char ** <var>url</var>)</em></dt>
<dd><p><var>key</var>: Holds the PKCS 11 key
</p>
<p><var>detailed</var>: non zero if a detailed URL is required
</p>
<p><var>url</var>: will contain an allocated url
</p>
<p>This function will export a URL identifying the given key.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005fgenerate-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_generate</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005fgenerate"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005fgenerate"></a>Function: <em>int</em> <strong>gnutls_pkcs11_privkey_generate</strong> <em>(const char * <var>url</var>, gnutls_pk_algorithm_t <var>pk</var>, unsigned int <var>bits</var>, const char * <var>label</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>url</var>: a token URL
</p>
<p><var>pk</var>: the public key algorithm
</p>
<p><var>bits</var>: the security bits
</p>
<p><var>label</var>: a label
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will generate a private key in the specified
by the  <code>url</code> token. The private key will be generate within
the token and will not be exportable.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005fgenerate2-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_generate2</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005fgenerate2"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005fgenerate2"></a>Function: <em>int</em> <strong>gnutls_pkcs11_privkey_generate2</strong> <em>(const char * <var>url</var>, gnutls_pk_algorithm_t <var>pk</var>, unsigned int <var>bits</var>, const char * <var>label</var>, gnutls_x509_crt_fmt_t <var>fmt</var>, gnutls_datum_t * <var>pubkey</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>url</var>: a token URL
</p>
<p><var>pk</var>: the public key algorithm
</p>
<p><var>bits</var>: the security bits
</p>
<p><var>label</var>: a label
</p>
<p><var>fmt</var>: the format of output params. PEM or DER
</p>
<p><var>pubkey</var>: will hold the public key (may be <code>NULL</code> )
</p>
<p><var>flags</var>: zero or an OR&rsquo;ed sequence of <code>GNUTLS_PKCS11_OBJ_FLAGs</code> 
</p>
<p>This function will generate a private key in the specified
by the  <code>url</code> token. The private key will be generate within
the token and will not be exportable. This function will
store the DER-encoded public key in the SubjectPublicKeyInfo format 
in  <code>pubkey</code> . The  <code>pubkey</code> should be deinitialized using <code>gnutls_free()</code> .
</p>
<p>Note that when generating an elliptic curve key, the curve
can be substituted in the place of the bits parameter using the
<code>GNUTLS_CURVE_TO_BITS()</code>  macro.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.5
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005fgenerate3-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_generate3</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005fgenerate3"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005fgenerate3"></a>Function: <em>int</em> <strong>gnutls_pkcs11_privkey_generate3</strong> <em>(const char * <var>url</var>, gnutls_pk_algorithm_t <var>pk</var>, unsigned int <var>bits</var>, const char * <var>label</var>, const gnutls_datum_t * <var>cid</var>, gnutls_x509_crt_fmt_t <var>fmt</var>, gnutls_datum_t * <var>pubkey</var>, unsigned int <var>key_usage</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>url</var>: a token URL
</p>
<p><var>pk</var>: the public key algorithm
</p>
<p><var>bits</var>: the security bits
</p>
<p><var>label</var>: a label
</p>
<p><var>cid</var>: The CKA_ID to use for the new object
</p>
<p><var>fmt</var>: the format of output params. PEM or DER
</p>
<p><var>pubkey</var>: will hold the public key (may be <code>NULL</code> )
</p>
<p><var>key_usage</var>: One of GNUTLS_KEY_*
</p>
<p><var>flags</var>: zero or an OR&rsquo;ed sequence of <code>GNUTLS_PKCS11_OBJ_FLAGs</code> 
</p>
<p>This function will generate a private key in the specified
by the  <code>url</code> token. The private key will be generate within
the token and will not be exportable. This function will
store the DER-encoded public key in the SubjectPublicKeyInfo format 
in  <code>pubkey</code> . The  <code>pubkey</code> should be deinitialized using <code>gnutls_free()</code> .
</p>
<p>Note that when generating an elliptic curve key, the curve
can be substituted in the place of the bits parameter using the
<code>GNUTLS_CURVE_TO_BITS()</code>  macro.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005fget_005finfo-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_get_info</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005fget_005finfo"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005fget_005finfo"></a>Function: <em>int</em> <strong>gnutls_pkcs11_privkey_get_info</strong> <em>(gnutls_pkcs11_privkey_t <var>pkey</var>, gnutls_pkcs11_obj_info_t <var>itype</var>, void * <var>output</var>, size_t * <var>output_size</var>)</em></dt>
<dd><p><var>pkey</var>: should contain a <code>gnutls_pkcs11_privkey_t</code>  type
</p>
<p><var>itype</var>: Denotes the type of information requested
</p>
<p><var>output</var>: where output will be stored
</p>
<p><var>output_size</var>: contains the maximum size of the output and will be overwritten with actual
</p>
<p>This function will return information about the PKCS 11 private key such
as the label, id as well as token information where the key is stored. When
output is text it returns null terminated string although <code>output_size</code>  contains
the size of the actual data only.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005fget_005fpk_005falgorithm-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_get_pk_algorithm</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005fget_005fpk_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005fget_005fpk_005falgorithm"></a>Function: <em>int</em> <strong>gnutls_pkcs11_privkey_get_pk_algorithm</strong> <em>(gnutls_pkcs11_privkey_t <var>key</var>, unsigned int * <var>bits</var>)</em></dt>
<dd><p><var>key</var>: should contain a <code>gnutls_pkcs11_privkey_t</code>  type
</p>
<p><var>bits</var>: if bits is non null it will hold the size of the parameters&rsquo; in bits
</p>
<p>This function will return the public key algorithm of a private
key.
</p>
<p><strong>Returns:</strong> a member of the <code>gnutls_pk_algorithm_t</code>  enumeration on
success, or a negative error code on error.
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005fimport_005furl-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_import_url</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005fimport_005furl"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005fimport_005furl"></a>Function: <em>int</em> <strong>gnutls_pkcs11_privkey_import_url</strong> <em>(gnutls_pkcs11_privkey_t <var>pkey</var>, const char * <var>url</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>url</var>: a PKCS 11 url identifying the key
</p>
<p><var>flags</var>: Or sequence of GNUTLS_PKCS11_OBJ_* flags
</p>
<p>This function will &quot;import&quot; a PKCS 11 URL identifying a private
key to the <code>gnutls_pkcs11_privkey_t</code>  type. In reality since
in most cases keys cannot be exported, the private key structure
is being associated with the available operations on the token.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005finit-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_init</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005finit"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005finit"></a>Function: <em>int</em> <strong>gnutls_pkcs11_privkey_init</strong> <em>(gnutls_pkcs11_privkey_t * <var>key</var>)</em></dt>
<dd><p><var>key</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize an private key structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005fset_005fpin_005ffunction-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_set_pin_function</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005fset_005fpin_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005fset_005fpin_005ffunction"></a>Function: <em>void</em> <strong>gnutls_pkcs11_privkey_set_pin_function</strong> <em>(gnutls_pkcs11_privkey_t <var>key</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</em></dt>
<dd><p><var>key</var>: The private key
</p>
<p><var>fn</var>: the callback
</p>
<p><var>userdata</var>: data associated with the callback
</p>
<p>This function will set a callback function to be used when
required to access the object. This function overrides the global
set using <code>gnutls_pkcs11_set_pin_function()</code> .
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fprivkey_005fstatus-1"></a>
<h4 class="subheading">gnutls_pkcs11_privkey_status</h4>
<a name="gnutls_005fpkcs11_005fprivkey_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fprivkey_005fstatus"></a>Function: <em>int</em> <strong>gnutls_pkcs11_privkey_status</strong> <em>(gnutls_pkcs11_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: Holds the key
</p>
<p>Checks the status of the private key token.
</p>
<p><strong>Returns:</strong> this function will return non-zero if the token 
holding the private key is still available (inserted), and zero otherwise.
</p>
<p><strong>Since:</strong> 3.1.9
</p></dd></dl>

<a name="gnutls_005fpkcs11_005freinit-1"></a>
<h4 class="subheading">gnutls_pkcs11_reinit</h4>
<a name="gnutls_005fpkcs11_005freinit"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005freinit"></a>Function: <em>int</em> <strong>gnutls_pkcs11_reinit</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>This function will reinitialize the PKCS 11 subsystem in gnutls. 
This is required by PKCS 11 when an application uses <code>fork()</code> . The
reinitialization function must be called on the child.
</p>
<p>Note that since GnuTLS 3.3.0, the reinitialization of the PKCS <code>11</code> 
subsystem occurs automatically after fork.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fset_005fpin_005ffunction-1"></a>
<h4 class="subheading">gnutls_pkcs11_set_pin_function</h4>
<a name="gnutls_005fpkcs11_005fset_005fpin_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fset_005fpin_005ffunction"></a>Function: <em>void</em> <strong>gnutls_pkcs11_set_pin_function</strong> <em>(gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</em></dt>
<dd><p><var>fn</var>: The PIN callback, a <code>gnutls_pin_callback_t()</code>  function.
</p>
<p><var>userdata</var>: data to be supplied to callback
</p>
<p>This function will set a callback function to be used when a PIN is
required for PKCS 11 operations.  See
<code>gnutls_pin_callback_t()</code>  on how the callback should behave.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005fset_005ftoken_005ffunction-1"></a>
<h4 class="subheading">gnutls_pkcs11_set_token_function</h4>
<a name="gnutls_005fpkcs11_005fset_005ftoken_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005fset_005ftoken_005ffunction"></a>Function: <em>void</em> <strong>gnutls_pkcs11_set_token_function</strong> <em>(gnutls_pkcs11_token_callback_t <var>fn</var>, void * <var>userdata</var>)</em></dt>
<dd><p><var>fn</var>: The token callback
</p>
<p><var>userdata</var>: data to be supplied to callback
</p>
<p>This function will set a callback function to be used when a token
needs to be inserted to continue PKCS 11 operations.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005ftoken_005fget_005fflags-1"></a>
<h4 class="subheading">gnutls_pkcs11_token_get_flags</h4>
<a name="gnutls_005fpkcs11_005ftoken_005fget_005fflags"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005ftoken_005fget_005fflags"></a>Function: <em>int</em> <strong>gnutls_pkcs11_token_get_flags</strong> <em>(const char * <var>url</var>, unsigned int * <var>flags</var>)</em></dt>
<dd><p><var>url</var>: should contain a PKCS 11 URL
</p>
<p><var>flags</var>: The output flags (GNUTLS_PKCS11_TOKEN_*)
</p>
<p>This function will return information about the PKCS 11 token flags.
</p>
<p>The supported flags are: <code>GNUTLS_PKCS11_TOKEN_HW</code>  and <code>GNUTLS_PKCS11_TOKEN_TRUSTED</code> .
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005ftoken_005fget_005finfo-1"></a>
<h4 class="subheading">gnutls_pkcs11_token_get_info</h4>
<a name="gnutls_005fpkcs11_005ftoken_005fget_005finfo"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005ftoken_005fget_005finfo"></a>Function: <em>int</em> <strong>gnutls_pkcs11_token_get_info</strong> <em>(const char * <var>url</var>, gnutls_pkcs11_token_info_t <var>ttype</var>, void * <var>output</var>, size_t * <var>output_size</var>)</em></dt>
<dd><p><var>url</var>: should contain a PKCS 11 URL
</p>
<p><var>ttype</var>: Denotes the type of information requested
</p>
<p><var>output</var>: where output will be stored
</p>
<p><var>output_size</var>: contains the maximum size of the output and will be overwritten with actual
</p>
<p>This function will return information about the PKCS 11 token such
as the label, id, etc.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success or a negative error code
on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005ftoken_005fget_005fmechanism-1"></a>
<h4 class="subheading">gnutls_pkcs11_token_get_mechanism</h4>
<a name="gnutls_005fpkcs11_005ftoken_005fget_005fmechanism"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005ftoken_005fget_005fmechanism"></a>Function: <em>int</em> <strong>gnutls_pkcs11_token_get_mechanism</strong> <em>(const char * <var>url</var>, unsigned int <var>idx</var>, unsigned long * <var>mechanism</var>)</em></dt>
<dd><p><var>url</var>: should contain a PKCS 11 URL
</p>
<p><var>idx</var>: The index of the mechanism
</p>
<p><var>mechanism</var>: The PKCS <code>11</code>  mechanism ID
</p>
<p>This function will return the names of the supported mechanisms
by the token. It should be called with an increasing index until
it return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005ftoken_005fget_005frandom-1"></a>
<h4 class="subheading">gnutls_pkcs11_token_get_random</h4>
<a name="gnutls_005fpkcs11_005ftoken_005fget_005frandom"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005ftoken_005fget_005frandom"></a>Function: <em>int</em> <strong>gnutls_pkcs11_token_get_random</strong> <em>(const char * <var>token_url</var>, void * <var>rnddata</var>, size_t <var>len</var>)</em></dt>
<dd><p><var>token_url</var>: A PKCS <code>11</code>  URL specifying a token
</p>
<p><var>rnddata</var>: A pointer to the memory area to be filled with random data
</p>
<p><var>len</var>: The number of bytes of randomness to request
</p>
<p>This function will get random data from the given token.
It will store rnddata and fill the memory pointed to by rnddata with
len random bytes from the token.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs11_005ftoken_005fget_005furl-1"></a>
<h4 class="subheading">gnutls_pkcs11_token_get_url</h4>
<a name="gnutls_005fpkcs11_005ftoken_005fget_005furl"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005ftoken_005fget_005furl"></a>Function: <em>int</em> <strong>gnutls_pkcs11_token_get_url</strong> <em>(unsigned int <var>seq</var>, gnutls_pkcs11_url_type_t <var>detailed</var>, char ** <var>url</var>)</em></dt>
<dd><p><var>seq</var>: sequence number starting from 0
</p>
<p><var>detailed</var>: non zero if a detailed URL is required
</p>
<p><var>url</var>: will contain an allocated url
</p>
<p>This function will return the URL for each token available
in system. The url has to be released using <code>gnutls_free()</code> 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned,
<code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code>  if the sequence number
exceeds the available tokens, otherwise a negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpkcs11_005ftoken_005finit-1"></a>
<h4 class="subheading">gnutls_pkcs11_token_init</h4>
<a name="gnutls_005fpkcs11_005ftoken_005finit"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005ftoken_005finit"></a>Function: <em>int</em> <strong>gnutls_pkcs11_token_init</strong> <em>(const char * <var>token_url</var>, const char * <var>so_pin</var>, const char * <var>label</var>)</em></dt>
<dd><p><var>token_url</var>: A PKCS <code>11</code>  URL specifying a token
</p>
<p><var>so_pin</var>: Security Officer&rsquo;s PIN
</p>
<p><var>label</var>: A name to be used for the token
</p>
<p>This function will initialize (format) a token. If the token is
at a factory defaults state the security officer&rsquo;s PIN given will be
set to be the default. Otherwise it should match the officer&rsquo;s PIN.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs11_005ftoken_005fset_005fpin-1"></a>
<h4 class="subheading">gnutls_pkcs11_token_set_pin</h4>
<a name="gnutls_005fpkcs11_005ftoken_005fset_005fpin"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005ftoken_005fset_005fpin"></a>Function: <em>int</em> <strong>gnutls_pkcs11_token_set_pin</strong> <em>(const char * <var>token_url</var>, const char * <var>oldpin</var>, const char * <var>newpin</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>token_url</var>: A PKCS <code>11</code>  URL specifying a token
</p>
<p><var>oldpin</var>: old user&rsquo;s PIN
</p>
<p><var>newpin</var>: new user&rsquo;s PIN
</p>
<p><var>flags</var>: one of <code>gnutls_pin_flag_t</code> .
</p>
<p>This function will modify or set a user&rsquo;s PIN for the given token. 
If it is called to set a user pin for first time the oldpin must
be NULL.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fpkcs11_005ftype_005fget_005fname-1"></a>
<h4 class="subheading">gnutls_pkcs11_type_get_name</h4>
<a name="gnutls_005fpkcs11_005ftype_005fget_005fname"></a><dl>
<dt><a name="index-gnutls_005fpkcs11_005ftype_005fget_005fname"></a>Function: <em>const char *</em> <strong>gnutls_pkcs11_type_get_name</strong> <em>(gnutls_pkcs11_obj_type_t <var>type</var>)</em></dt>
<dd><p><var>type</var>: Holds the PKCS 11 object type, a <code>gnutls_pkcs11_obj_type_t</code> .
</p>
<p>This function will return a human readable description of the
PKCS11 object type  <code>obj</code> .  It will return &quot;Unknown&quot; for unknown
types.
</p>
<p><strong>Returns:</strong> human readable string labeling the PKCS11 object type
 <code>type</code> .
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fimport_005fpkcs11-1"></a>
<h4 class="subheading">gnutls_x509_crt_import_pkcs11</h4>
<a name="gnutls_005fx509_005fcrt_005fimport_005fpkcs11"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fimport_005fpkcs11"></a>Function: <em>int</em> <strong>gnutls_x509_crt_import_pkcs11</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_pkcs11_obj_t <var>pkcs11_crt</var>)</em></dt>
<dd><p><var>crt</var>: A certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>pkcs11_crt</var>: A PKCS 11 object that contains a certificate
</p>
<p>This function will import a PKCS 11 certificate to a <code>gnutls_x509_crt_t</code> 
structure.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005flist_005fimport_005fpkcs11-1"></a>
<h4 class="subheading">gnutls_x509_crt_list_import_pkcs11</h4>
<a name="gnutls_005fx509_005fcrt_005flist_005fimport_005fpkcs11"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005flist_005fimport_005fpkcs11"></a>Function: <em>int</em> <strong>gnutls_x509_crt_list_import_pkcs11</strong> <em>(gnutls_x509_crt_t * <var>certs</var>, unsigned int <var>cert_max</var>, gnutls_pkcs11_obj_t * const <var>objs</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>certs</var>: A list of certificates of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>cert_max</var>: The maximum size of the list
</p>
<p><var>objs</var>: A list of PKCS 11 objects
</p>
<p><var>flags</var>: 0 for now
</p>
<p>This function will import a PKCS 11 certificate list to a list of 
<code>gnutls_x509_crt_t</code>  type. These must not be initialized.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>


<hr>
<a name="TPM-API"></a>
<div class="header">
<p>
Next: <a href="#Abstract-key-API" accesskey="n" rel="next">Abstract key API</a>, Previous: <a href="#PKCS-11-API" accesskey="p" rel="prev">PKCS 11 API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="TPM-API-1"></a>
<h3 class="section">E.9 TPM API</h3>

<p>The following functions are to be used for TPM handling.
Their prototypes lie in <samp>gnutls/tpm.h</samp>.
</p>

<a name="gnutls_005ftpm_005fget_005fregistered-1"></a>
<h4 class="subheading">gnutls_tpm_get_registered</h4>
<a name="gnutls_005ftpm_005fget_005fregistered"></a><dl>
<dt><a name="index-gnutls_005ftpm_005fget_005fregistered"></a>Function: <em>int</em> <strong>gnutls_tpm_get_registered</strong> <em>(gnutls_tpm_key_list_t * <var>list</var>)</em></dt>
<dd><p><var>list</var>: a list to store the keys
</p>
<p>This function will get a list of stored keys in the TPM. The uuid
of those keys
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005ftpm_005fkey_005flist_005fdeinit-1"></a>
<h4 class="subheading">gnutls_tpm_key_list_deinit</h4>
<a name="gnutls_005ftpm_005fkey_005flist_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005ftpm_005fkey_005flist_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_tpm_key_list_deinit</strong> <em>(gnutls_tpm_key_list_t <var>list</var>)</em></dt>
<dd><p><var>list</var>: a list of the keys
</p>
<p>This function will deinitialize the list of stored keys in the TPM.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005ftpm_005fkey_005flist_005fget_005furl-1"></a>
<h4 class="subheading">gnutls_tpm_key_list_get_url</h4>
<a name="gnutls_005ftpm_005fkey_005flist_005fget_005furl"></a><dl>
<dt><a name="index-gnutls_005ftpm_005fkey_005flist_005fget_005furl"></a>Function: <em>int</em> <strong>gnutls_tpm_key_list_get_url</strong> <em>(gnutls_tpm_key_list_t <var>list</var>, unsigned int <var>idx</var>, char ** <var>url</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>list</var>: a list of the keys
</p>
<p><var>idx</var>: The index of the key (starting from zero)
</p>
<p><var>url</var>: The URL to be returned
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will return for each given index a URL of
the corresponding key.
If the provided index is out of bounds then <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> 
is returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005ftpm_005fprivkey_005fdelete-1"></a>
<h4 class="subheading">gnutls_tpm_privkey_delete</h4>
<a name="gnutls_005ftpm_005fprivkey_005fdelete"></a><dl>
<dt><a name="index-gnutls_005ftpm_005fprivkey_005fdelete-2"></a>Function: <em>int</em> <strong>gnutls_tpm_privkey_delete</strong> <em>(const char * <var>url</var>, const char * <var>srk_password</var>)</em></dt>
<dd><p><var>url</var>: the URL describing the key
</p>
<p><var>srk_password</var>: a password for the SRK key
</p>
<p>This function will unregister the private key from the TPM
chip. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005ftpm_005fprivkey_005fgenerate-1"></a>
<h4 class="subheading">gnutls_tpm_privkey_generate</h4>
<a name="gnutls_005ftpm_005fprivkey_005fgenerate"></a><dl>
<dt><a name="index-gnutls_005ftpm_005fprivkey_005fgenerate-1"></a>Function: <em>int</em> <strong>gnutls_tpm_privkey_generate</strong> <em>(gnutls_pk_algorithm_t <var>pk</var>, unsigned int <var>bits</var>, const char * <var>srk_password</var>, const char * <var>key_password</var>, gnutls_tpmkey_fmt_t <var>format</var>, gnutls_x509_crt_fmt_t <var>pub_format</var>, gnutls_datum_t * <var>privkey</var>, gnutls_datum_t * <var>pubkey</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pk</var>: the public key algorithm
</p>
<p><var>bits</var>: the security bits
</p>
<p><var>srk_password</var>: a password to protect the exported key (optional)
</p>
<p><var>key_password</var>: the password for the TPM (optional)
</p>
<p><var>format</var>: the format of the private key
</p>
<p><var>pub_format</var>: the format of the public key
</p>
<p><var>privkey</var>: the generated key
</p>
<p><var>pubkey</var>: the corresponding public key (may be null)
</p>
<p><var>flags</var>: should be a list of GNUTLS_TPM_* flags
</p>
<p>This function will generate a private key in the TPM
chip. The private key will be generated within the chip
and will be exported in a wrapped with TPM&rsquo;s master key
form. Furthermore the wrapped key can be protected with
the provided  <code>password</code> .
</p>
<p>Note that bits in TPM is quantized value. If the input value
is not one of the allowed values, then it will be quantized to
one of 512, 1024, 2048, 4096, 8192 and 16384.
</p>
<p>Allowed flags are:
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>


<hr>
<a name="Abstract-key-API"></a>
<div class="header">
<p>
Next: <a href="#DANE-API" accesskey="n" rel="next">DANE API</a>, Previous: <a href="#TPM-API" accesskey="p" rel="prev">TPM API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Abstract-key-API-1"></a>
<h3 class="section">E.10 Abstract key API</h3>

<p>The following functions are to be used for abstract key handling.
Their prototypes lie in <samp>gnutls/abstract.h</samp>.
</p>

<a name="gnutls_005fcertificate_005fset_005fkey-1"></a>
<h4 class="subheading">gnutls_certificate_set_key</h4>
<a name="gnutls_005fcertificate_005fset_005fkey"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fkey-1"></a>Function: <em>int</em> <strong>gnutls_certificate_set_key</strong> <em>(gnutls_certificate_credentials_t <var>res</var>, const char ** <var>names</var>, int <var>names_size</var>, gnutls_pcert_st * <var>pcert_list</var>, int <var>pcert_list_size</var>, gnutls_privkey_t <var>key</var>)</em></dt>
<dd><p><var>res</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>names</var>: is an array of DNS name of the certificate (NULL if none)
</p>
<p><var>names_size</var>: holds the size of the names list
</p>
<p><var>pcert_list</var>: contains a certificate list (path) for the specified private key
</p>
<p><var>pcert_list_size</var>: holds the size of the certificate list
</p>
<p><var>key</var>: is a <code>gnutls_privkey_t</code>  key
</p>
<p>This function sets a certificate/private key pair in the
gnutls_certificate_credentials_t type.  This function may be
called more than once, in case multiple keys/certificates exist for
the server.  For clients that wants to send more than its own end
entity certificate (e.g., also an intermediate CA cert) then put
the certificate chain in  <code>pcert_list</code> . 
</p>
<p>Note that the  <code>pcert_list</code> and  <code>key</code> will become part of the credentials 
structure and must not be deallocated. They will be automatically deallocated 
when the  <code>res</code> type is deinitialized.
</p>
<p>If that function fails to load the  <code>res</code> structure is at an undefined state, it must
not be reused to load other keys or certificates.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  (0) on success, or a negative error code.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fcertificate_005fset_005fretrieve_005ffunction2-1"></a>
<h4 class="subheading">gnutls_certificate_set_retrieve_function2</h4>
<a name="gnutls_005fcertificate_005fset_005fretrieve_005ffunction2"></a><dl>
<dt><a name="index-gnutls_005fcertificate_005fset_005fretrieve_005ffunction2"></a>Function: <em>void</em> <strong>gnutls_certificate_set_retrieve_function2</strong> <em>(gnutls_certificate_credentials_t <var>cred</var>, gnutls_certificate_retrieve_function2 * <var>func</var>)</em></dt>
<dd><p><var>cred</var>: is a <code>gnutls_certificate_credentials_t</code>  type.
</p>
<p><var>func</var>: is the callback function
</p>
<p>This function sets a callback to be called in order to retrieve the
certificate to be used in the handshake. The callback will take control
only if a certificate is requested by the peer.
</p>
<p>The callback&rsquo;s function prototype is:
int (*callback)(gnutls_session_t, const gnutls_datum_t* req_ca_dn, int nreqs,
const gnutls_pk_algorithm_t* pk_algos, int pk_algos_length, gnutls_pcert_st** pcert,
unsigned int *pcert_length, gnutls_privkey_t * pkey);
</p>
<p><code>req_ca_dn</code> is only used in X.509 certificates.
Contains a list with the CA names that the server considers trusted.
This is a hint and typically the client should send a certificate that is signed
by one of these CAs. These names, when available, are DER encoded. To get a more
meaningful value use the function <code>gnutls_x509_rdn_get()</code> .
</p>
<p><code>pk_algos</code> contains a list with server&rsquo;s acceptable signature algorithms.
The certificate returned should support the server&rsquo;s given algorithms.
</p>
<p><code>pcert</code> should contain a single certificate and public key or a list of them.
</p>
<p><code>pcert_length</code> is the size of the previous list.
</p>
<p><code>pkey</code> is the private key.
</p>
<p>If the callback function is provided then gnutls will call it, in the
handshake, after the certificate request message has been received.
All the provided by the callback values will not be released or
modified by gnutls.
</p>
<p>In server side pk_algos and req_ca_dn are NULL.
</p>
<p>The callback function should set the certificate list to be sent,
and return 0 on success. If no certificate was selected then the
number of certificates should be set to zero. The value (-1)
indicates error and the handshake will be terminated. If both certificates
are set in the credentials and a callback is available, the callback
takes predence.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpcert_005fdeinit-1"></a>
<h4 class="subheading">gnutls_pcert_deinit</h4>
<a name="gnutls_005fpcert_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fpcert_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_pcert_deinit</strong> <em>(gnutls_pcert_st * <var>pcert</var>)</em></dt>
<dd><p><var>pcert</var>: The structure to be deinitialized
</p>
<p>This function will deinitialize a pcert structure.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpcert_005fexport_005fopenpgp-1"></a>
<h4 class="subheading">gnutls_pcert_export_openpgp</h4>
<a name="gnutls_005fpcert_005fexport_005fopenpgp"></a><dl>
<dt><a name="index-gnutls_005fpcert_005fexport_005fopenpgp"></a>Function: <em>int</em> <strong>gnutls_pcert_export_openpgp</strong> <em>(gnutls_pcert_st * <var>pcert</var>, gnutls_openpgp_crt_t * <var>crt</var>)</em></dt>
<dd><p><var>pcert</var>: The pcert structure.
</p>
<p><var>crt</var>: An initialized <code>gnutls_openpgp_crt_t</code> .
</p>
<p>Converts the given <code>gnutls_pcert_t</code>  type into a <code>gnutls_openpgp_crt_t</code> .
This function only works if the type of  <code>pcert</code> is <code>GNUTLS_CRT_OPENPGP</code> .
When successful, the value written to  <code>crt</code> must be freed with
<code>gnutls_openpgp_crt_deinit()</code>  when no longer needed.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fpcert_005fexport_005fx509-1"></a>
<h4 class="subheading">gnutls_pcert_export_x509</h4>
<a name="gnutls_005fpcert_005fexport_005fx509"></a><dl>
<dt><a name="index-gnutls_005fpcert_005fexport_005fx509"></a>Function: <em>int</em> <strong>gnutls_pcert_export_x509</strong> <em>(gnutls_pcert_st * <var>pcert</var>, gnutls_x509_crt_t * <var>crt</var>)</em></dt>
<dd><p><var>pcert</var>: The pcert structure.
</p>
<p><var>crt</var>: An initialized <code>gnutls_x509_crt_t</code> .
</p>
<p>Converts the given <code>gnutls_pcert_t</code>  type into a <code>gnutls_x509_crt_t</code> .
This function only works if the type of  <code>pcert</code> is <code>GNUTLS_CRT_X509</code> .
When successful, the value written to  <code>crt</code> must be freed with
<code>gnutls_x509_crt_deinit()</code>  when no longer needed.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fpcert_005fimport_005fopenpgp-1"></a>
<h4 class="subheading">gnutls_pcert_import_openpgp</h4>
<a name="gnutls_005fpcert_005fimport_005fopenpgp"></a><dl>
<dt><a name="index-gnutls_005fpcert_005fimport_005fopenpgp"></a>Function: <em>int</em> <strong>gnutls_pcert_import_openpgp</strong> <em>(gnutls_pcert_st * <var>pcert</var>, gnutls_openpgp_crt_t <var>crt</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pcert</var>: The pcert structure
</p>
<p><var>crt</var>: The raw certificate to be imported
</p>
<p><var>flags</var>: zero for now
</p>
<p>This convenience function will import the given certificate to a
<code>gnutls_pcert_st</code>  structure. The structure must be deinitialized
afterwards using <code>gnutls_pcert_deinit()</code> ;
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpcert_005fimport_005fopenpgp_005fraw-1"></a>
<h4 class="subheading">gnutls_pcert_import_openpgp_raw</h4>
<a name="gnutls_005fpcert_005fimport_005fopenpgp_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpcert_005fimport_005fopenpgp_005fraw"></a>Function: <em>int</em> <strong>gnutls_pcert_import_openpgp_raw</strong> <em>(gnutls_pcert_st * <var>pcert</var>, const gnutls_datum_t * <var>cert</var>, gnutls_openpgp_crt_fmt_t <var>format</var>, gnutls_openpgp_keyid_t <var>keyid</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pcert</var>: The pcert structure
</p>
<p><var>cert</var>: The raw certificate to be imported
</p>
<p><var>format</var>: The format of the certificate
</p>
<p><var>keyid</var>: The key ID to use (NULL for the master key)
</p>
<p><var>flags</var>: zero for now
</p>
<p>This convenience function will import the given certificate to a
<code>gnutls_pcert_st</code>  structure. The structure must be deinitialized
afterwards using <code>gnutls_pcert_deinit()</code> ;
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpcert_005fimport_005fx509-1"></a>
<h4 class="subheading">gnutls_pcert_import_x509</h4>
<a name="gnutls_005fpcert_005fimport_005fx509"></a><dl>
<dt><a name="index-gnutls_005fpcert_005fimport_005fx509"></a>Function: <em>int</em> <strong>gnutls_pcert_import_x509</strong> <em>(gnutls_pcert_st * <var>pcert</var>, gnutls_x509_crt_t <var>crt</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pcert</var>: The pcert structure
</p>
<p><var>crt</var>: The certificate to be imported
</p>
<p><var>flags</var>: zero for now
</p>
<p>This convenience function will import the given certificate to a
<code>gnutls_pcert_st</code>  structure. The structure must be deinitialized
afterwards using <code>gnutls_pcert_deinit()</code> ;
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpcert_005fimport_005fx509_005flist-1"></a>
<h4 class="subheading">gnutls_pcert_import_x509_list</h4>
<a name="gnutls_005fpcert_005fimport_005fx509_005flist"></a><dl>
<dt><a name="index-gnutls_005fpcert_005fimport_005fx509_005flist"></a>Function: <em>int</em> <strong>gnutls_pcert_import_x509_list</strong> <em>(gnutls_pcert_st * <var>pcert</var>, gnutls_x509_crt_t * <var>crt</var>, unsigned * <var>ncrt</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pcert</var>: The pcert structure
</p>
<p><var>crt</var>: The certificates to be imported
</p>
<p><var>ncrt</var>: The number of certificates
</p>
<p><var>flags</var>: zero or <code>GNUTLS_X509_CRT_LIST_SORT</code> 
</p>
<p>This convenience function will import the given certificate to a
<code>gnutls_pcert_st</code>  structure. The structure must be deinitialized
afterwards using <code>gnutls_pcert_deinit()</code> ;
</p>
<p>In the case <code>GNUTLS_X509_CRT_LIST_SORT</code>  is specified and that
function cannot sort the list, <code>GNUTLS_E_CERTIFICATE_LIST_UNSORTED</code> 
will be returned. Currently sorting can fail if the list size
exceeds an internal constraint (16).
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fpcert_005fimport_005fx509_005fraw-1"></a>
<h4 class="subheading">gnutls_pcert_import_x509_raw</h4>
<a name="gnutls_005fpcert_005fimport_005fx509_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpcert_005fimport_005fx509_005fraw"></a>Function: <em>int</em> <strong>gnutls_pcert_import_x509_raw</strong> <em>(gnutls_pcert_st * <var>pcert</var>, const gnutls_datum_t * <var>cert</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pcert</var>: The pcert structure
</p>
<p><var>cert</var>: The raw certificate to be imported
</p>
<p><var>format</var>: The format of the certificate
</p>
<p><var>flags</var>: zero for now
</p>
<p>This convenience function will import the given certificate to a
<code>gnutls_pcert_st</code>  structure. The structure must be deinitialized
afterwards using <code>gnutls_pcert_deinit()</code> ;
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpcert_005flist_005fimport_005fx509_005fraw-1"></a>
<h4 class="subheading">gnutls_pcert_list_import_x509_raw</h4>
<a name="gnutls_005fpcert_005flist_005fimport_005fx509_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpcert_005flist_005fimport_005fx509_005fraw"></a>Function: <em>int</em> <strong>gnutls_pcert_list_import_x509_raw</strong> <em>(gnutls_pcert_st * <var>pcerts</var>, unsigned int * <var>pcert_max</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pcerts</var>: The structures to store the parsed certificate. Must not be initialized.
</p>
<p><var>pcert_max</var>: Initially must hold the maximum number of certs. It will be updated with the number of certs available.
</p>
<p><var>data</var>: The certificates.
</p>
<p><var>format</var>: One of DER or PEM.
</p>
<p><var>flags</var>: must be (0) or an OR&rsquo;d sequence of gnutls_certificate_import_flags.
</p>
<p>This function will convert the given PEM encoded certificate list
to the native gnutls_x509_crt_t format. The output will be stored
in  <code>certs</code> .  They will be automatically initialized.
</p>
<p>If the Certificate is PEM encoded it should have a header of &quot;X509
CERTIFICATE&quot;, or &quot;CERTIFICATE&quot;.
</p>
<p><strong>Returns:</strong> the number of certificates read or a negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fdecrypt_005fdata-1"></a>
<h4 class="subheading">gnutls_privkey_decrypt_data</h4>
<a name="gnutls_005fprivkey_005fdecrypt_005fdata"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fdecrypt_005fdata-1"></a>Function: <em>int</em> <strong>gnutls_privkey_decrypt_data</strong> <em>(gnutls_privkey_t <var>key</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>ciphertext</var>, gnutls_datum_t * <var>plaintext</var>)</em></dt>
<dd><p><var>key</var>: Holds the key
</p>
<p><var>flags</var>: zero for now
</p>
<p><var>ciphertext</var>: holds the data to be decrypted
</p>
<p><var>plaintext</var>: will contain the decrypted data, allocated with <code>gnutls_malloc()</code> 
</p>
<p>This function will decrypt the given data using the algorithm
supported by the private key.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fdeinit-1"></a>
<h4 class="subheading">gnutls_privkey_deinit</h4>
<a name="gnutls_005fprivkey_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_privkey_deinit</strong> <em>(gnutls_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: The key to be deinitialized
</p>
<p>This function will deinitialize a private key structure.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fexport_005fdsa_005fraw-1"></a>
<h4 class="subheading">gnutls_privkey_export_dsa_raw</h4>
<a name="gnutls_005fprivkey_005fexport_005fdsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fexport_005fdsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_privkey_export_dsa_raw</strong> <em>(gnutls_privkey_t <var>key</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>g</var>, gnutls_datum_t * <var>y</var>, gnutls_datum_t * <var>x</var>)</em></dt>
<dd><p><var>key</var>: Holds the public key
</p>
<p><var>p</var>: will hold the p
</p>
<p><var>q</var>: will hold the q
</p>
<p><var>g</var>: will hold the g
</p>
<p><var>y</var>: will hold the y
</p>
<p><var>x</var>: will hold the x
</p>
<p>This function will export the DSA private key&rsquo;s parameters found
in the given structure. The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fexport_005fecc_005fraw-1"></a>
<h4 class="subheading">gnutls_privkey_export_ecc_raw</h4>
<a name="gnutls_005fprivkey_005fexport_005fecc_005fraw"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fexport_005fecc_005fraw"></a>Function: <em>int</em> <strong>gnutls_privkey_export_ecc_raw</strong> <em>(gnutls_privkey_t <var>key</var>, gnutls_ecc_curve_t * <var>curve</var>, gnutls_datum_t * <var>x</var>, gnutls_datum_t * <var>y</var>, gnutls_datum_t * <var>k</var>)</em></dt>
<dd><p><var>key</var>: Holds the public key
</p>
<p><var>curve</var>: will hold the curve
</p>
<p><var>x</var>: will hold the x coordinate
</p>
<p><var>y</var>: will hold the y coordinate
</p>
<p><var>k</var>: will hold the private key
</p>
<p>This function will export the ECC private key&rsquo;s parameters found
in the given structure. The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fexport_005fopenpgp-1"></a>
<h4 class="subheading">gnutls_privkey_export_openpgp</h4>
<a name="gnutls_005fprivkey_005fexport_005fopenpgp"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fexport_005fopenpgp"></a>Function: <em>int</em> <strong>gnutls_privkey_export_openpgp</strong> <em>(gnutls_privkey_t <var>pkey</var>, gnutls_openpgp_privkey_t * <var>key</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>key</var>: Location for the key to be exported.
</p>
<p>Converts the given abstract private key to a <code>gnutls_openpgp_privkey_t</code> 
type. The key must be of type <code>GNUTLS_PRIVKEY_OPENPGP</code> . The key
returned in  <code>key</code> must be deinitialized with
<code>gnutls_openpgp_privkey_deinit()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fexport_005fpkcs11-1"></a>
<h4 class="subheading">gnutls_privkey_export_pkcs11</h4>
<a name="gnutls_005fprivkey_005fexport_005fpkcs11"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fexport_005fpkcs11"></a>Function: <em>int</em> <strong>gnutls_privkey_export_pkcs11</strong> <em>(gnutls_privkey_t <var>pkey</var>, gnutls_pkcs11_privkey_t * <var>key</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>key</var>: Location for the key to be exported.
</p>
<p>Converts the given abstract private key to a <code>gnutls_pkcs11_privkey_t</code> 
type. The key must be of type <code>GNUTLS_PRIVKEY_PKCS11</code> . The key
returned in  <code>key</code> must be deinitialized with
<code>gnutls_pkcs11_privkey_deinit()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fexport_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_privkey_export_rsa_raw</h4>
<a name="gnutls_005fprivkey_005fexport_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fexport_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_privkey_export_rsa_raw</strong> <em>(gnutls_privkey_t <var>key</var>, gnutls_datum_t * <var>m</var>, gnutls_datum_t * <var>e</var>, gnutls_datum_t * <var>d</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>u</var>, gnutls_datum_t * <var>e1</var>, gnutls_datum_t * <var>e2</var>)</em></dt>
<dd><p><var>key</var>: Holds the certificate
</p>
<p><var>m</var>: will hold the modulus
</p>
<p><var>e</var>: will hold the public exponent
</p>
<p><var>d</var>: will hold the private exponent
</p>
<p><var>p</var>: will hold the first prime (p)
</p>
<p><var>q</var>: will hold the second prime (q)
</p>
<p><var>u</var>: will hold the coefficient
</p>
<p><var>e1</var>: will hold e1 = d mod (p-1)
</p>
<p><var>e2</var>: will hold e2 = d mod (q-1)
</p>
<p>This function will export the RSA private key&rsquo;s parameters found
in the given structure. The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fexport_005fx509-1"></a>
<h4 class="subheading">gnutls_privkey_export_x509</h4>
<a name="gnutls_005fprivkey_005fexport_005fx509"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fexport_005fx509"></a>Function: <em>int</em> <strong>gnutls_privkey_export_x509</strong> <em>(gnutls_privkey_t <var>pkey</var>, gnutls_x509_privkey_t * <var>key</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>key</var>: Location for the key to be exported.
</p>
<p>Converts the given abstract private key to a <code>gnutls_x509_privkey_t</code> 
type. The key must be of type <code>GNUTLS_PRIVKEY_X509</code> . The key returned
in  <code>key</code> must be deinitialized with <code>gnutls_x509_privkey_deinit()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fgenerate-1"></a>
<h4 class="subheading">gnutls_privkey_generate</h4>
<a name="gnutls_005fprivkey_005fgenerate"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fgenerate"></a>Function: <em>int</em> <strong>gnutls_privkey_generate</strong> <em>(gnutls_privkey_t <var>pkey</var>, gnutls_pk_algorithm_t <var>algo</var>, unsigned int <var>bits</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>algo</var>: is one of the algorithms in <code>gnutls_pk_algorithm_t</code> .
</p>
<p><var>bits</var>: the size of the modulus
</p>
<p><var>flags</var>: unused for now.  Must be 0.
</p>
<p>This function will generate a random private key. Note that this
function must be called on an empty private key.
</p>
<p>Note that when generating an elliptic curve key, the curve
can be substituted in the place of the bits parameter using the
<code>GNUTLS_CURVE_TO_BITS()</code>  macro.
</p>
<p>Do not set the number of bits directly, use <code>gnutls_sec_param_to_pk_bits()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fget_005fpk_005falgorithm-1"></a>
<h4 class="subheading">gnutls_privkey_get_pk_algorithm</h4>
<a name="gnutls_005fprivkey_005fget_005fpk_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fget_005fpk_005falgorithm"></a>Function: <em>int</em> <strong>gnutls_privkey_get_pk_algorithm</strong> <em>(gnutls_privkey_t <var>key</var>, unsigned int * <var>bits</var>)</em></dt>
<dd><p><var>key</var>: should contain a <code>gnutls_privkey_t</code>  type
</p>
<p><var>bits</var>: If set will return the number of bits of the parameters (may be NULL)
</p>
<p>This function will return the public key algorithm of a private
key and if possible will return a number of bits that indicates
the security parameter of the key.
</p>
<p><strong>Returns:</strong> a member of the <code>gnutls_pk_algorithm_t</code>  enumeration on
success, or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fget_005ftype-1"></a>
<h4 class="subheading">gnutls_privkey_get_type</h4>
<a name="gnutls_005fprivkey_005fget_005ftype"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fget_005ftype"></a>Function: <em>gnutls_privkey_type_t</em> <strong>gnutls_privkey_get_type</strong> <em>(gnutls_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: should contain a <code>gnutls_privkey_t</code>  type
</p>
<p>This function will return the type of the private key. This is
actually the type of the subsystem used to set this private key.
</p>
<p><strong>Returns:</strong> a member of the <code>gnutls_privkey_type_t</code>  enumeration on
success, or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005fdsa_005fraw-1"></a>
<h4 class="subheading">gnutls_privkey_import_dsa_raw</h4>
<a name="gnutls_005fprivkey_005fimport_005fdsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fdsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_privkey_import_dsa_raw</strong> <em>(gnutls_privkey_t <var>key</var>, const gnutls_datum_t * <var>p</var>, const gnutls_datum_t * <var>q</var>, const gnutls_datum_t * <var>g</var>, const gnutls_datum_t * <var>y</var>, const gnutls_datum_t * <var>x</var>)</em></dt>
<dd><p><var>key</var>: The structure to store the parsed key
</p>
<p><var>p</var>: holds the p
</p>
<p><var>q</var>: holds the q
</p>
<p><var>g</var>: holds the g
</p>
<p><var>y</var>: holds the y
</p>
<p><var>x</var>: holds the x
</p>
<p>This function will convert the given DSA raw parameters to the
native <code>gnutls_privkey_t</code>  format.  The output will be stored
in  <code>key</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005fecc_005fraw-1"></a>
<h4 class="subheading">gnutls_privkey_import_ecc_raw</h4>
<a name="gnutls_005fprivkey_005fimport_005fecc_005fraw"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fecc_005fraw"></a>Function: <em>int</em> <strong>gnutls_privkey_import_ecc_raw</strong> <em>(gnutls_privkey_t <var>key</var>, gnutls_ecc_curve_t <var>curve</var>, const gnutls_datum_t * <var>x</var>, const gnutls_datum_t * <var>y</var>, const gnutls_datum_t * <var>k</var>)</em></dt>
<dd><p><var>key</var>: The key
</p>
<p><var>curve</var>: holds the curve
</p>
<p><var>x</var>: holds the x
</p>
<p><var>y</var>: holds the y
</p>
<p><var>k</var>: holds the k
</p>
<p>This function will convert the given elliptic curve parameters to the
native <code>gnutls_privkey_t</code>  format.  The output will be stored
in  <code>key</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005fext-1"></a>
<h4 class="subheading">gnutls_privkey_import_ext</h4>
<a name="gnutls_005fprivkey_005fimport_005fext"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fext"></a>Function: <em>int</em> <strong>gnutls_privkey_import_ext</strong> <em>(gnutls_privkey_t <var>pkey</var>, gnutls_pk_algorithm_t <var>pk</var>, void * <var>userdata</var>, gnutls_privkey_sign_func <var>sign_func</var>, gnutls_privkey_decrypt_func <var>decrypt_func</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>pk</var>: The public key algorithm
</p>
<p><var>userdata</var>: private data to be provided to the callbacks
</p>
<p><var>sign_func</var>: callback for signature operations
</p>
<p><var>decrypt_func</var>: callback for decryption operations
</p>
<p><var>flags</var>: Flags for the import
</p>
<p>This function will associate the given callbacks with the
<code>gnutls_privkey_t</code>  type. At least one of the two callbacks
must be non-null.
</p>
<p>See also <code>gnutls_privkey_import_ext3()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005fext2-1"></a>
<h4 class="subheading">gnutls_privkey_import_ext2</h4>
<a name="gnutls_005fprivkey_005fimport_005fext2"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fext2"></a>Function: <em>int</em> <strong>gnutls_privkey_import_ext2</strong> <em>(gnutls_privkey_t <var>pkey</var>, gnutls_pk_algorithm_t <var>pk</var>, void * <var>userdata</var>, gnutls_privkey_sign_func <var>sign_fn</var>, gnutls_privkey_decrypt_func <var>decrypt_fn</var>, gnutls_privkey_deinit_func <var>deinit_fn</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>pk</var>: The public key algorithm
</p>
<p><var>userdata</var>: private data to be provided to the callbacks
</p>
<p><var>sign_fn</var>: callback for signature operations
</p>
<p><var>decrypt_fn</var>: callback for decryption operations
</p>
<p><var>deinit_fn</var>: a deinitialization function
</p>
<p><var>flags</var>: Flags for the import
</p>
<p>This function will associate the given callbacks with the
<code>gnutls_privkey_t</code>  type. At least one of the two callbacks
must be non-null. If a deinitialization function is provided
then flags is assumed to contain <code>GNUTLS_PRIVKEY_IMPORT_AUTO_RELEASE</code> .
</p>
<p>Note that the signing function is supposed to &quot;raw&quot; sign data, i.e.,
without any hashing or preprocessing. In case of RSA the DigestInfo
will be provided, and the signing function is expected to do the PKCS <code>1</code> 
1.5 padding and the exponentiation.
</p>
<p>See also <code>gnutls_privkey_import_ext3()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005fext3-1"></a>
<h4 class="subheading">gnutls_privkey_import_ext3</h4>
<a name="gnutls_005fprivkey_005fimport_005fext3"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fext3-1"></a>Function: <em>int</em> <strong>gnutls_privkey_import_ext3</strong> <em>(gnutls_privkey_t <var>pkey</var>, void * <var>userdata</var>, gnutls_privkey_sign_func <var>sign_fn</var>, gnutls_privkey_decrypt_func <var>decrypt_fn</var>, gnutls_privkey_deinit_func <var>deinit_fn</var>, gnutls_privkey_info_func <var>info_fn</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>userdata</var>: private data to be provided to the callbacks
</p>
<p><var>sign_fn</var>: callback for signature operations
</p>
<p><var>decrypt_fn</var>: callback for decryption operations
</p>
<p><var>deinit_fn</var>: a deinitialization function
</p>
<p><var>info_fn</var>: returns info about the public key algorithm (should not be <code>NULL</code> )
</p>
<p><var>flags</var>: Flags for the import
</p>
<p>This function will associate the given callbacks with the
<code>gnutls_privkey_t</code>  type. At least one of the two callbacks
must be non-null. If a deinitialization function is provided
then flags is assumed to contain <code>GNUTLS_PRIVKEY_IMPORT_AUTO_RELEASE</code> .
</p>
<p>Note that the signing function is supposed to &quot;raw&quot; sign data, i.e.,
without any hashing or preprocessing. In case of RSA the DigestInfo
will be provided, and the signing function is expected to do the PKCS <code>1</code> 
1.5 padding and the exponentiation.
</p>
<p>The  <code>info_fn</code> must provide information on the algorithms supported by
this private key, and should support the flags <code>GNUTLS_PRIVKEY_INFO_PK_ALGO</code>  and
<code>GNUTLS_PRIVKEY_INFO_SIGN_ALGO</code> . It must return -1 on unknown flags.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005fopenpgp-1"></a>
<h4 class="subheading">gnutls_privkey_import_openpgp</h4>
<a name="gnutls_005fprivkey_005fimport_005fopenpgp"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fopenpgp"></a>Function: <em>int</em> <strong>gnutls_privkey_import_openpgp</strong> <em>(gnutls_privkey_t <var>pkey</var>, gnutls_openpgp_privkey_t <var>key</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>key</var>: The private key to be imported
</p>
<p><var>flags</var>: Flags for the import
</p>
<p>This function will import the given private key to the abstract
<code>gnutls_privkey_t</code>  type.
</p>
<p>The <code>gnutls_openpgp_privkey_t</code>  object must not be deallocated
during the lifetime of this structure. The subkey set as
preferred will be used, or the master key otherwise.
</p>
<p><code>flags</code> might be zero or one of <code>GNUTLS_PRIVKEY_IMPORT_AUTO_RELEASE</code> 
and <code>GNUTLS_PRIVKEY_IMPORT_COPY</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005fopenpgp_005fraw-1"></a>
<h4 class="subheading">gnutls_privkey_import_openpgp_raw</h4>
<a name="gnutls_005fprivkey_005fimport_005fopenpgp_005fraw"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fopenpgp_005fraw"></a>Function: <em>int</em> <strong>gnutls_privkey_import_openpgp_raw</strong> <em>(gnutls_privkey_t <var>pkey</var>, const gnutls_datum_t * <var>data</var>, gnutls_openpgp_crt_fmt_t <var>format</var>, const gnutls_openpgp_keyid_t <var>keyid</var>, const char * <var>password</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>data</var>: The private key data to be imported
</p>
<p><var>format</var>: The format of the private key
</p>
<p><var>keyid</var>: The key id to use (optional)
</p>
<p><var>password</var>: A password (optional)
</p>
<p>This function will import the given private key to the abstract
<code>gnutls_privkey_t</code>  type. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005fpkcs11-1"></a>
<h4 class="subheading">gnutls_privkey_import_pkcs11</h4>
<a name="gnutls_005fprivkey_005fimport_005fpkcs11"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fpkcs11"></a>Function: <em>int</em> <strong>gnutls_privkey_import_pkcs11</strong> <em>(gnutls_privkey_t <var>pkey</var>, gnutls_pkcs11_privkey_t <var>key</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>key</var>: The private key to be imported
</p>
<p><var>flags</var>: Flags for the import
</p>
<p>This function will import the given private key to the abstract
<code>gnutls_privkey_t</code>  type.
</p>
<p>The <code>gnutls_pkcs11_privkey_t</code>  object must not be deallocated
during the lifetime of this structure.
</p>
<p><code>flags</code> might be zero or one of <code>GNUTLS_PRIVKEY_IMPORT_AUTO_RELEASE</code> 
and <code>GNUTLS_PRIVKEY_IMPORT_COPY</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005fpkcs11_005furl-1"></a>
<h4 class="subheading">gnutls_privkey_import_pkcs11_url</h4>
<a name="gnutls_005fprivkey_005fimport_005fpkcs11_005furl"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fpkcs11_005furl"></a>Function: <em>int</em> <strong>gnutls_privkey_import_pkcs11_url</strong> <em>(gnutls_privkey_t <var>key</var>, const char * <var>url</var>)</em></dt>
<dd><p><var>key</var>: A key of type <code>gnutls_pubkey_t</code> 
</p>
<p><var>url</var>: A PKCS 11 url
</p>
<p>This function will import a PKCS 11 private key to a <code>gnutls_private_key_t</code> 
type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_privkey_import_rsa_raw</h4>
<a name="gnutls_005fprivkey_005fimport_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_privkey_import_rsa_raw</strong> <em>(gnutls_privkey_t <var>key</var>, const gnutls_datum_t * <var>m</var>, const gnutls_datum_t * <var>e</var>, const gnutls_datum_t * <var>d</var>, const gnutls_datum_t * <var>p</var>, const gnutls_datum_t * <var>q</var>, const gnutls_datum_t * <var>u</var>, const gnutls_datum_t * <var>e1</var>, const gnutls_datum_t * <var>e2</var>)</em></dt>
<dd><p><var>key</var>: The structure to store the parsed key
</p>
<p><var>m</var>: holds the modulus
</p>
<p><var>e</var>: holds the public exponent
</p>
<p><var>d</var>: holds the private exponent
</p>
<p><var>p</var>: holds the first prime (p)
</p>
<p><var>q</var>: holds the second prime (q)
</p>
<p><var>u</var>: holds the coefficient (optional)
</p>
<p><var>e1</var>: holds e1 = d mod (p-1) (optional)
</p>
<p><var>e2</var>: holds e2 = d mod (q-1) (optional)
</p>
<p>This function will convert the given RSA raw parameters to the
native <code>gnutls_privkey_t</code>  format.  The output will be stored in
 <code>key</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005ftpm_005fraw-1"></a>
<h4 class="subheading">gnutls_privkey_import_tpm_raw</h4>
<a name="gnutls_005fprivkey_005fimport_005ftpm_005fraw"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005ftpm_005fraw"></a>Function: <em>int</em> <strong>gnutls_privkey_import_tpm_raw</strong> <em>(gnutls_privkey_t <var>pkey</var>, const gnutls_datum_t * <var>fdata</var>, gnutls_tpmkey_fmt_t <var>format</var>, const char * <var>srk_password</var>, const char * <var>key_password</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>fdata</var>: The TPM key to be imported
</p>
<p><var>format</var>: The format of the private key
</p>
<p><var>srk_password</var>: The password for the SRK key (optional)
</p>
<p><var>key_password</var>: A password for the key (optional)
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will import the given private key to the abstract
<code>gnutls_privkey_t</code>  type. 
</p>
<p>With respect to passwords the same as in <code>gnutls_privkey_import_tpm_url()</code>  apply.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005ftpm_005furl-1"></a>
<h4 class="subheading">gnutls_privkey_import_tpm_url</h4>
<a name="gnutls_005fprivkey_005fimport_005ftpm_005furl"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005ftpm_005furl-1"></a>Function: <em>int</em> <strong>gnutls_privkey_import_tpm_url</strong> <em>(gnutls_privkey_t <var>pkey</var>, const char * <var>url</var>, const char * <var>srk_password</var>, const char * <var>key_password</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>url</var>: The URL of the TPM key to be imported
</p>
<p><var>srk_password</var>: The password for the SRK key (optional)
</p>
<p><var>key_password</var>: A password for the key (optional)
</p>
<p><var>flags</var>: One of the GNUTLS_PRIVKEY_* flags
</p>
<p>This function will import the given private key to the abstract
<code>gnutls_privkey_t</code>  type.
</p>
<p>Note that unless <code>GNUTLS_PRIVKEY_DISABLE_CALLBACKS</code> 
is specified, if incorrect (or NULL) passwords are given
the PKCS11 callback functions will be used to obtain the
correct passwords. Otherwise if the SRK password is wrong
<code>GNUTLS_E_TPM_SRK_PASSWORD_ERROR</code>  is returned and if the key password
is wrong or not provided then <code>GNUTLS_E_TPM_KEY_PASSWORD_ERROR</code> 
is returned. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005furl-1"></a>
<h4 class="subheading">gnutls_privkey_import_url</h4>
<a name="gnutls_005fprivkey_005fimport_005furl"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005furl-1"></a>Function: <em>int</em> <strong>gnutls_privkey_import_url</strong> <em>(gnutls_privkey_t <var>key</var>, const char * <var>url</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: A key of type <code>gnutls_privkey_t</code> 
</p>
<p><var>url</var>: A PKCS 11 url
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will import a PKCS11 or TPM URL as a
private key. The supported URL types can be checked
using <code>gnutls_url_is_supported()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005fx509-1"></a>
<h4 class="subheading">gnutls_privkey_import_x509</h4>
<a name="gnutls_005fprivkey_005fimport_005fx509"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fx509"></a>Function: <em>int</em> <strong>gnutls_privkey_import_x509</strong> <em>(gnutls_privkey_t <var>pkey</var>, gnutls_x509_privkey_t <var>key</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>key</var>: The private key to be imported
</p>
<p><var>flags</var>: Flags for the import
</p>
<p>This function will import the given private key to the abstract
<code>gnutls_privkey_t</code>  type.
</p>
<p>The <code>gnutls_x509_privkey_t</code>  object must not be deallocated
during the lifetime of this structure.
</p>
<p><code>flags</code> might be zero or one of <code>GNUTLS_PRIVKEY_IMPORT_AUTO_RELEASE</code> 
and <code>GNUTLS_PRIVKEY_IMPORT_COPY</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fimport_005fx509_005fraw-1"></a>
<h4 class="subheading">gnutls_privkey_import_x509_raw</h4>
<a name="gnutls_005fprivkey_005fimport_005fx509_005fraw"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fimport_005fx509_005fraw-1"></a>Function: <em>int</em> <strong>gnutls_privkey_import_x509_raw</strong> <em>(gnutls_privkey_t <var>pkey</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, const char * <var>password</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The private key
</p>
<p><var>data</var>: The private key data to be imported
</p>
<p><var>format</var>: The format of the private key
</p>
<p><var>password</var>: A password (optional)
</p>
<p><var>flags</var>: an ORed sequence of gnutls_pkcs_encrypt_flags_t
</p>
<p>This function will import the given private key to the abstract
<code>gnutls_privkey_t</code>  type. 
</p>
<p>The supported formats are basic unencrypted key, PKCS8, PKCS12, 
and the openssl format.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005finit-1"></a>
<h4 class="subheading">gnutls_privkey_init</h4>
<a name="gnutls_005fprivkey_005finit"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005finit"></a>Function: <em>int</em> <strong>gnutls_privkey_init</strong> <em>(gnutls_privkey_t * <var>key</var>)</em></dt>
<dd><p><var>key</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize a private key.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fset_005fpin_005ffunction-1"></a>
<h4 class="subheading">gnutls_privkey_set_pin_function</h4>
<a name="gnutls_005fprivkey_005fset_005fpin_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fset_005fpin_005ffunction"></a>Function: <em>void</em> <strong>gnutls_privkey_set_pin_function</strong> <em>(gnutls_privkey_t <var>key</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</em></dt>
<dd><p><var>key</var>: A key of type <code>gnutls_privkey_t</code> 
</p>
<p><var>fn</var>: the callback
</p>
<p><var>userdata</var>: data associated with the callback
</p>
<p>This function will set a callback function to be used when
required to access the object. This function overrides any other
global PIN functions.
</p>
<p>Note that this function must be called right after initialization
to have effect.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fsign_005fdata-1"></a>
<h4 class="subheading">gnutls_privkey_sign_data</h4>
<a name="gnutls_005fprivkey_005fsign_005fdata"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fsign_005fdata-1"></a>Function: <em>int</em> <strong>gnutls_privkey_sign_data</strong> <em>(gnutls_privkey_t <var>signer</var>, gnutls_digest_algorithm_t <var>hash</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>data</var>, gnutls_datum_t * <var>signature</var>)</em></dt>
<dd><p><var>signer</var>: Holds the key
</p>
<p><var>hash</var>: should be a digest algorithm
</p>
<p><var>flags</var>: Zero or one of <code>gnutls_privkey_flags_t</code> 
</p>
<p><var>data</var>: holds the data to be signed
</p>
<p><var>signature</var>: will contain the signature allocated with <code>gnutls_malloc()</code> 
</p>
<p>This function will sign the given data using a signature algorithm
supported by the private key. Signature algorithms are always used
together with a hash functions.  Different hash functions may be
used for the RSA algorithm, but only the SHA family for the DSA keys.
</p>
<p>You may use <code>gnutls_pubkey_get_preferred_hash_algorithm()</code>  to determine
the hash algorithm.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fsign_005fhash-1"></a>
<h4 class="subheading">gnutls_privkey_sign_hash</h4>
<a name="gnutls_005fprivkey_005fsign_005fhash"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fsign_005fhash-1"></a>Function: <em>int</em> <strong>gnutls_privkey_sign_hash</strong> <em>(gnutls_privkey_t <var>signer</var>, gnutls_digest_algorithm_t <var>hash_algo</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>hash_data</var>, gnutls_datum_t * <var>signature</var>)</em></dt>
<dd><p><var>signer</var>: Holds the signer&rsquo;s key
</p>
<p><var>hash_algo</var>: The hash algorithm used
</p>
<p><var>flags</var>: Zero or one of <code>gnutls_privkey_flags_t</code> 
</p>
<p><var>hash_data</var>: holds the data to be signed
</p>
<p><var>signature</var>: will contain newly allocated signature
</p>
<p>This function will sign the given hashed data using a signature algorithm
supported by the private key. Signature algorithms are always used
together with a hash functions.  Different hash functions may be
used for the RSA algorithm, but only SHA-XXX for the DSA keys.
</p>
<p>You may use <code>gnutls_pubkey_get_preferred_hash_algorithm()</code>  to determine
the hash algorithm.
</p>
<p>Note that if <code>GNUTLS_PRIVKEY_SIGN_FLAG_TLS1_RSA</code>  flag is specified this function
will ignore  <code>hash_algo</code> and perform a raw PKCS1 signature.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fprivkey_005fstatus-1"></a>
<h4 class="subheading">gnutls_privkey_status</h4>
<a name="gnutls_005fprivkey_005fstatus"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fstatus"></a>Function: <em>int</em> <strong>gnutls_privkey_status</strong> <em>(gnutls_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: Holds the key
</p>
<p>Checks the status of the private key token. This function
is an actual wrapper over <code>gnutls_pkcs11_privkey_status()</code> , and
if the private key is a PKCS <code>11</code>  token it will check whether
it is inserted or not.
</p>
<p><strong>Returns:</strong> this function will return non-zero if the token 
holding the private key is still available (inserted), and zero otherwise.
</p>
<p><strong>Since:</strong> 3.1.10
</p></dd></dl>

<a name="gnutls_005fprivkey_005fverify_005fparams-1"></a>
<h4 class="subheading">gnutls_privkey_verify_params</h4>
<a name="gnutls_005fprivkey_005fverify_005fparams"></a><dl>
<dt><a name="index-gnutls_005fprivkey_005fverify_005fparams"></a>Function: <em>int</em> <strong>gnutls_privkey_verify_params</strong> <em>(gnutls_privkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: should contain a <code>gnutls_privkey_t</code>  type
</p>
<p>This function will verify the private key parameters.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fdeinit-1"></a>
<h4 class="subheading">gnutls_pubkey_deinit</h4>
<a name="gnutls_005fpubkey_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_pubkey_deinit</strong> <em>(gnutls_pubkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: The key to be deinitialized
</p>
<p>This function will deinitialize a public key structure.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fencrypt_005fdata-1"></a>
<h4 class="subheading">gnutls_pubkey_encrypt_data</h4>
<a name="gnutls_005fpubkey_005fencrypt_005fdata"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fencrypt_005fdata-1"></a>Function: <em>int</em> <strong>gnutls_pubkey_encrypt_data</strong> <em>(gnutls_pubkey_t <var>key</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>plaintext</var>, gnutls_datum_t * <var>ciphertext</var>)</em></dt>
<dd><p><var>key</var>: Holds the public key
</p>
<p><var>flags</var>: should be 0 for now
</p>
<p><var>plaintext</var>: The data to be encrypted
</p>
<p><var>ciphertext</var>: contains the encrypted data
</p>
<p>This function will encrypt the given data, using the public
key.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fexport-1"></a>
<h4 class="subheading">gnutls_pubkey_export</h4>
<a name="gnutls_005fpubkey_005fexport"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fexport"></a>Function: <em>int</em> <strong>gnutls_pubkey_export</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_x509_crt_fmt_t <var>format</var>, void * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>key</var>: Holds the certificate
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>output_data</var>: will contain a certificate PEM or DER encoded
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will export the public key to DER or PEM format.
The contents of the exported data is the SubjectPublicKeyInfo
X.509 structure.
</p>
<p>If the buffer provided is not long enough to hold the output, then
*output_data_size is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  will
be returned.
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN CERTIFICATE&quot;.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fexport2-1"></a>
<h4 class="subheading">gnutls_pubkey_export2</h4>
<a name="gnutls_005fpubkey_005fexport2"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fexport2-1"></a>Function: <em>int</em> <strong>gnutls_pubkey_export2</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_x509_crt_fmt_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>key</var>: Holds the certificate
</p>
<p><var>format</var>: the format of output params. One of PEM or DER.
</p>
<p><var>out</var>: will contain a certificate PEM or DER encoded
</p>
<p>This function will export the public key to DER or PEM format.
The contents of the exported data is the SubjectPublicKeyInfo
X.509 structure.
</p>
<p>The output buffer will be allocated using <code>gnutls_malloc()</code> .
</p>
<p>If the structure is PEM encoded, it will have a header
of &quot;BEGIN CERTIFICATE&quot;.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fpubkey_005fexport_005fdsa_005fraw-1"></a>
<h4 class="subheading">gnutls_pubkey_export_dsa_raw</h4>
<a name="gnutls_005fpubkey_005fexport_005fdsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fexport_005fdsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_pubkey_export_dsa_raw</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_datum_t * <var>p</var>, gnutls_datum_t * <var>q</var>, gnutls_datum_t * <var>g</var>, gnutls_datum_t * <var>y</var>)</em></dt>
<dd><p><var>key</var>: Holds the public key
</p>
<p><var>p</var>: will hold the p (may be <code>NULL</code> )
</p>
<p><var>q</var>: will hold the q (may be <code>NULL</code> )
</p>
<p><var>g</var>: will hold the g (may be <code>NULL</code> )
</p>
<p><var>y</var>: will hold the y (may be <code>NULL</code> )
</p>
<p>This function will export the DSA public key&rsquo;s parameters found in
the given certificate.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p>This function allows for <code>NULL</code>  parameters since 3.4.1.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fexport_005fecc_005fraw-1"></a>
<h4 class="subheading">gnutls_pubkey_export_ecc_raw</h4>
<a name="gnutls_005fpubkey_005fexport_005fecc_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fexport_005fecc_005fraw"></a>Function: <em>int</em> <strong>gnutls_pubkey_export_ecc_raw</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_ecc_curve_t * <var>curve</var>, gnutls_datum_t * <var>x</var>, gnutls_datum_t * <var>y</var>)</em></dt>
<dd><p><var>key</var>: Holds the public key
</p>
<p><var>curve</var>: will hold the curve (may be <code>NULL</code> )
</p>
<p><var>x</var>: will hold x (may be <code>NULL</code> )
</p>
<p><var>y</var>: will hold y (may be <code>NULL</code> )
</p>
<p>This function will export the ECC public key&rsquo;s parameters found in
the given key.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p>This function allows for <code>NULL</code>  parameters since 3.4.1.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fexport_005fecc_005fx962-1"></a>
<h4 class="subheading">gnutls_pubkey_export_ecc_x962</h4>
<a name="gnutls_005fpubkey_005fexport_005fecc_005fx962"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fexport_005fecc_005fx962"></a>Function: <em>int</em> <strong>gnutls_pubkey_export_ecc_x962</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_datum_t * <var>parameters</var>, gnutls_datum_t * <var>ecpoint</var>)</em></dt>
<dd><p><var>key</var>: Holds the public key
</p>
<p><var>parameters</var>: DER encoding of an ANSI X9.62 parameters
</p>
<p><var>ecpoint</var>: DER encoding of ANSI X9.62 ECPoint
</p>
<p>This function will export the ECC public key&rsquo;s parameters found in
the given certificate.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fexport_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_pubkey_export_rsa_raw</h4>
<a name="gnutls_005fpubkey_005fexport_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fexport_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_pubkey_export_rsa_raw</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_datum_t * <var>m</var>, gnutls_datum_t * <var>e</var>)</em></dt>
<dd><p><var>key</var>: Holds the certificate
</p>
<p><var>m</var>: will hold the modulus (may be <code>NULL</code> )
</p>
<p><var>e</var>: will hold the public exponent (may be <code>NULL</code> )
</p>
<p>This function will export the RSA public key&rsquo;s parameters found in
the given structure.  The new parameters will be allocated using
<code>gnutls_malloc()</code>  and will be stored in the appropriate datum.
</p>
<p>This function allows for <code>NULL</code>  parameters since 3.4.1.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fget_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_pubkey_get_key_id</h4>
<a name="gnutls_005fpubkey_005fget_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fget_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_pubkey_get_key_id</strong> <em>(gnutls_pubkey_t <var>key</var>, unsigned int <var>flags</var>, unsigned char * <var>output_data</var>, size_t * <var>output_data_size</var>)</em></dt>
<dd><p><var>key</var>: Holds the public key
</p>
<p><var>flags</var>: should be one of the flags from <code>gnutls_keyid_flags_t</code> 
</p>
<p><var>output_data</var>: will contain the key ID
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p>This function will return a unique ID that depends on the public
key parameters. This ID can be used in checking whether a
certificate corresponds to the given public key.
</p>
<p>If the buffer provided is not long enough to hold the output, then
*output_data_size is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  will
be returned.  The output will normally be a SHA-1 hash output,
which is 20 bytes.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fget_005fkey_005fusage-1"></a>
<h4 class="subheading">gnutls_pubkey_get_key_usage</h4>
<a name="gnutls_005fpubkey_005fget_005fkey_005fusage"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fget_005fkey_005fusage"></a>Function: <em>int</em> <strong>gnutls_pubkey_get_key_usage</strong> <em>(gnutls_pubkey_t <var>key</var>, unsigned int * <var>usage</var>)</em></dt>
<dd><p><var>key</var>: should contain a <code>gnutls_pubkey_t</code>  type
</p>
<p><var>usage</var>: If set will return the number of bits of the parameters (may be NULL)
</p>
<p>This function will return the key usage of the public key.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fget_005fopenpgp_005fkey_005fid-1"></a>
<h4 class="subheading">gnutls_pubkey_get_openpgp_key_id</h4>
<a name="gnutls_005fpubkey_005fget_005fopenpgp_005fkey_005fid"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fget_005fopenpgp_005fkey_005fid"></a>Function: <em>int</em> <strong>gnutls_pubkey_get_openpgp_key_id</strong> <em>(gnutls_pubkey_t <var>key</var>, unsigned int <var>flags</var>, unsigned char * <var>output_data</var>, size_t * <var>output_data_size</var>, unsigned int * <var>subkey</var>)</em></dt>
<dd><p><var>key</var>: Holds the public key
</p>
<p><var>flags</var>: should be 0 or <code>GNUTLS_PUBKEY_GET_OPENPGP_FINGERPRINT</code> 
</p>
<p><var>output_data</var>: will contain the key ID
</p>
<p><var>output_data_size</var>: holds the size of output_data (and will be
replaced by the actual size of parameters)
</p>
<p><var>subkey</var>: Will be non zero if the key ID corresponds to a subkey
</p>
<p>This function returns the OpenPGP key ID of the corresponding key.
The key is a unique ID that depends on the public
key parameters. 
</p>
<p>If the flag <code>GNUTLS_PUBKEY_GET_OPENPGP_FINGERPRINT</code>  is specified
this function returns the fingerprint of the master key.
</p>
<p>If the buffer provided is not long enough to hold the output, then
*output_data_size is updated and <code>GNUTLS_E_SHORT_MEMORY_BUFFER</code>  will
be returned.  The output is <code>GNUTLS_OPENPGP_KEYID_SIZE</code>  bytes long.
</p>
<p><strong>Returns:</strong> In case of failure a negative error code will be
returned, and 0 on success.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fget_005fpk_005falgorithm-1"></a>
<h4 class="subheading">gnutls_pubkey_get_pk_algorithm</h4>
<a name="gnutls_005fpubkey_005fget_005fpk_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fget_005fpk_005falgorithm"></a>Function: <em>int</em> <strong>gnutls_pubkey_get_pk_algorithm</strong> <em>(gnutls_pubkey_t <var>key</var>, unsigned int * <var>bits</var>)</em></dt>
<dd><p><var>key</var>: should contain a <code>gnutls_pubkey_t</code>  type
</p>
<p><var>bits</var>: If set will return the number of bits of the parameters (may be NULL)
</p>
<p>This function will return the public key algorithm of a public
key and if possible will return a number of bits that indicates
the security parameter of the key.
</p>
<p><strong>Returns:</strong> a member of the <code>gnutls_pk_algorithm_t</code>  enumeration on
success, or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fget_005fpreferred_005fhash_005falgorithm-1"></a>
<h4 class="subheading">gnutls_pubkey_get_preferred_hash_algorithm</h4>
<a name="gnutls_005fpubkey_005fget_005fpreferred_005fhash_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fget_005fpreferred_005fhash_005falgorithm"></a>Function: <em>int</em> <strong>gnutls_pubkey_get_preferred_hash_algorithm</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_digest_algorithm_t *         <var>hash</var>, unsigned int * <var>mand</var>)</em></dt>
<dd><p><var>key</var>: Holds the certificate
</p>
<p><var>hash</var>: The result of the call with the hash algorithm used for signature
</p>
<p><var>mand</var>: If non zero it means that the algorithm MUST use this hash. May be NULL.
</p>
<p>This function will read the certifcate and return the appropriate digest
algorithm to use for signing with this certificate. Some certificates (i.e.
DSA might not be able to sign without the preferred algorithm).
</p>
<p>To get the signature algorithm instead of just the hash use <code>gnutls_pk_to_sign()</code> 
with the algorithm of the certificate/key and the provided  <code>hash</code> .
</p>
<p><strong>Returns:</strong> the 0 if the hash algorithm is found. A negative error code is
returned on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport-1"></a>
<h4 class="subheading">gnutls_pubkey_import</h4>
<a name="gnutls_005fpubkey_005fimport"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport"></a>Function: <em>int</em> <strong>gnutls_pubkey_import</strong> <em>(gnutls_pubkey_t <var>key</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>)</em></dt>
<dd><p><var>key</var>: The public key. 
</p>
<p><var>data</var>: The DER or PEM encoded certificate. 
</p>
<p><var>format</var>: One of DER or PEM 
</p>
<p>This function will import the provided public key in
a SubjectPublicKeyInfo X.509 structure to a native
<code>gnutls_pubkey_t</code>  type. The output will be stored 
in  <code>key</code> . If the public key is PEM encoded it should have a header 
of &quot;PUBLIC KEY&quot;. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005fdsa_005fraw-1"></a>
<h4 class="subheading">gnutls_pubkey_import_dsa_raw</h4>
<a name="gnutls_005fpubkey_005fimport_005fdsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005fdsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_dsa_raw</strong> <em>(gnutls_pubkey_t <var>key</var>, const gnutls_datum_t * <var>p</var>, const gnutls_datum_t * <var>q</var>, const gnutls_datum_t * <var>g</var>, const gnutls_datum_t * <var>y</var>)</em></dt>
<dd><p><var>key</var>: The structure to store the parsed key
</p>
<p><var>p</var>: holds the p
</p>
<p><var>q</var>: holds the q
</p>
<p><var>g</var>: holds the g
</p>
<p><var>y</var>: holds the y
</p>
<p>This function will convert the given DSA raw parameters to the
native <code>gnutls_pubkey_t</code>  format.  The output will be stored
in  <code>key</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005fecc_005fraw-1"></a>
<h4 class="subheading">gnutls_pubkey_import_ecc_raw</h4>
<a name="gnutls_005fpubkey_005fimport_005fecc_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005fecc_005fraw"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_ecc_raw</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_ecc_curve_t <var>curve</var>, const gnutls_datum_t * <var>x</var>, const gnutls_datum_t * <var>y</var>)</em></dt>
<dd><p><var>key</var>: The structure to store the parsed key
</p>
<p><var>curve</var>: holds the curve
</p>
<p><var>x</var>: holds the x
</p>
<p><var>y</var>: holds the y
</p>
<p>This function will convert the given elliptic curve parameters to a
<code>gnutls_pubkey_t</code> .  The output will be stored in  <code>key</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005fecc_005fx962-1"></a>
<h4 class="subheading">gnutls_pubkey_import_ecc_x962</h4>
<a name="gnutls_005fpubkey_005fimport_005fecc_005fx962"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005fecc_005fx962"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_ecc_x962</strong> <em>(gnutls_pubkey_t <var>key</var>, const gnutls_datum_t * <var>parameters</var>, const gnutls_datum_t * <var>ecpoint</var>)</em></dt>
<dd><p><var>key</var>: The structure to store the parsed key
</p>
<p><var>parameters</var>: DER encoding of an ANSI X9.62 parameters
</p>
<p><var>ecpoint</var>: DER encoding of ANSI X9.62 ECPoint
</p>
<p>This function will convert the given elliptic curve parameters to a
<code>gnutls_pubkey_t</code> .  The output will be stored in  <code>key</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005fopenpgp-1"></a>
<h4 class="subheading">gnutls_pubkey_import_openpgp</h4>
<a name="gnutls_005fpubkey_005fimport_005fopenpgp"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005fopenpgp"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_openpgp</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_openpgp_crt_t <var>crt</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: The public key
</p>
<p><var>crt</var>: The certificate to be imported
</p>
<p><var>flags</var>: should be zero
</p>
<p>Imports a public key from an openpgp key. This function will import
the given public key to the abstract <code>gnutls_pubkey_t</code> 
type. The subkey set as preferred will be imported or the
master key otherwise.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005fopenpgp_005fraw-1"></a>
<h4 class="subheading">gnutls_pubkey_import_openpgp_raw</h4>
<a name="gnutls_005fpubkey_005fimport_005fopenpgp_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005fopenpgp_005fraw"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_openpgp_raw</strong> <em>(gnutls_pubkey_t <var>pkey</var>, const gnutls_datum_t * <var>data</var>, gnutls_openpgp_crt_fmt_t <var>format</var>, const gnutls_openpgp_keyid_t <var>keyid</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The public key
</p>
<p><var>data</var>: The public key data to be imported
</p>
<p><var>format</var>: The format of the public key
</p>
<p><var>keyid</var>: The key id to use (optional)
</p>
<p><var>flags</var>: Should be zero
</p>
<p>This function will import the given public key to the abstract
<code>gnutls_pubkey_t</code>  type. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005fpkcs11-1"></a>
<h4 class="subheading">gnutls_pubkey_import_pkcs11</h4>
<a name="gnutls_005fpubkey_005fimport_005fpkcs11"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005fpkcs11"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_pkcs11</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_pkcs11_obj_t <var>obj</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: The public key
</p>
<p><var>obj</var>: The parameters to be imported
</p>
<p><var>flags</var>: should be zero
</p>
<p>Imports a public key from a pkcs11 key. This function will import
the given public key to the abstract <code>gnutls_pubkey_t</code>  type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005fprivkey-1"></a>
<h4 class="subheading">gnutls_pubkey_import_privkey</h4>
<a name="gnutls_005fpubkey_005fimport_005fprivkey"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005fprivkey"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_privkey</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_privkey_t <var>pkey</var>, unsigned int <var>usage</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: The public key
</p>
<p><var>pkey</var>: The private key
</p>
<p><var>usage</var>: GNUTLS_KEY_* key usage flags.
</p>
<p><var>flags</var>: should be zero
</p>
<p>Imports the public key from a private.  This function will import
the given public key to the abstract <code>gnutls_pubkey_t</code>  type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005frsa_005fraw-1"></a>
<h4 class="subheading">gnutls_pubkey_import_rsa_raw</h4>
<a name="gnutls_005fpubkey_005fimport_005frsa_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005frsa_005fraw"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_rsa_raw</strong> <em>(gnutls_pubkey_t <var>key</var>, const gnutls_datum_t * <var>m</var>, const gnutls_datum_t * <var>e</var>)</em></dt>
<dd><p><var>key</var>: The key
</p>
<p><var>m</var>: holds the modulus
</p>
<p><var>e</var>: holds the public exponent
</p>
<p>This function will replace the parameters in the given structure.
The new parameters should be stored in the appropriate
gnutls_datum.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, or an negative error code.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005ftpm_005fraw-1"></a>
<h4 class="subheading">gnutls_pubkey_import_tpm_raw</h4>
<a name="gnutls_005fpubkey_005fimport_005ftpm_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005ftpm_005fraw"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_tpm_raw</strong> <em>(gnutls_pubkey_t <var>pkey</var>, const gnutls_datum_t * <var>fdata</var>, gnutls_tpmkey_fmt_t <var>format</var>, const char * <var>srk_password</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The public key
</p>
<p><var>fdata</var>: The TPM key to be imported
</p>
<p><var>format</var>: The format of the private key
</p>
<p><var>srk_password</var>: The password for the SRK key (optional)
</p>
<p><var>flags</var>: One of the GNUTLS_PUBKEY_* flags
</p>
<p>This function will import the public key from the provided TPM key
structure.
</p>
<p>With respect to passwords the same as in
<code>gnutls_pubkey_import_tpm_url()</code>  apply.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005ftpm_005furl-1"></a>
<h4 class="subheading">gnutls_pubkey_import_tpm_url</h4>
<a name="gnutls_005fpubkey_005fimport_005ftpm_005furl"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005ftpm_005furl-1"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_tpm_url</strong> <em>(gnutls_pubkey_t <var>pkey</var>, const char * <var>url</var>, const char * <var>srk_password</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The public key
</p>
<p><var>url</var>: The URL of the TPM key to be imported
</p>
<p><var>srk_password</var>: The password for the SRK key (optional)
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will import the given private key to the abstract
<code>gnutls_privkey_t</code>  type. 
</p>
<p>Note that unless <code>GNUTLS_PUBKEY_DISABLE_CALLBACKS</code> 
is specified, if incorrect (or NULL) passwords are given
the PKCS11 callback functions will be used to obtain the
correct passwords. Otherwise if the SRK password is wrong
<code>GNUTLS_E_TPM_SRK_PASSWORD_ERROR</code>  is returned.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005furl-1"></a>
<h4 class="subheading">gnutls_pubkey_import_url</h4>
<a name="gnutls_005fpubkey_005fimport_005furl"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005furl"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_url</strong> <em>(gnutls_pubkey_t <var>key</var>, const char * <var>url</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: A key of type <code>gnutls_pubkey_t</code> 
</p>
<p><var>url</var>: A PKCS 11 url
</p>
<p><var>flags</var>: One of GNUTLS_PKCS11_OBJ_* flags
</p>
<p>This function will import a public key from the provided URL.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005fx509-1"></a>
<h4 class="subheading">gnutls_pubkey_import_x509</h4>
<a name="gnutls_005fpubkey_005fimport_005fx509"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005fx509"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_x509</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_x509_crt_t <var>crt</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: The public key
</p>
<p><var>crt</var>: The certificate to be imported
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will import the given public key to the abstract
<code>gnutls_pubkey_t</code>  type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005fx509_005fcrq-1"></a>
<h4 class="subheading">gnutls_pubkey_import_x509_crq</h4>
<a name="gnutls_005fpubkey_005fimport_005fx509_005fcrq"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005fx509_005fcrq"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_x509_crq</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_x509_crq_t <var>crq</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>key</var>: The public key
</p>
<p><var>crq</var>: The certificate to be imported
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will import the given public key to the abstract
<code>gnutls_pubkey_t</code>  type.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.5
</p></dd></dl>

<a name="gnutls_005fpubkey_005fimport_005fx509_005fraw-1"></a>
<h4 class="subheading">gnutls_pubkey_import_x509_raw</h4>
<a name="gnutls_005fpubkey_005fimport_005fx509_005fraw"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fimport_005fx509_005fraw"></a>Function: <em>int</em> <strong>gnutls_pubkey_import_x509_raw</strong> <em>(gnutls_pubkey_t <var>pkey</var>, const gnutls_datum_t * <var>data</var>, gnutls_x509_crt_fmt_t <var>format</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>pkey</var>: The public key
</p>
<p><var>data</var>: The public key data to be imported
</p>
<p><var>format</var>: The format of the public key
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will import the given public key to the abstract
<code>gnutls_pubkey_t</code>  type. 
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.3
</p></dd></dl>

<a name="gnutls_005fpubkey_005finit-1"></a>
<h4 class="subheading">gnutls_pubkey_init</h4>
<a name="gnutls_005fpubkey_005finit"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005finit"></a>Function: <em>int</em> <strong>gnutls_pubkey_init</strong> <em>(gnutls_pubkey_t * <var>key</var>)</em></dt>
<dd><p><var>key</var>: A pointer to the type to be initialized
</p>
<p>This function will initialize a public key.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fprint-1"></a>
<h4 class="subheading">gnutls_pubkey_print</h4>
<a name="gnutls_005fpubkey_005fprint"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fprint"></a>Function: <em>int</em> <strong>gnutls_pubkey_print</strong> <em>(gnutls_pubkey_t <var>pubkey</var>, gnutls_certificate_print_formats_t <var>format</var>, gnutls_datum_t * <var>out</var>)</em></dt>
<dd><p><var>pubkey</var>: The data to be printed
</p>
<p><var>format</var>: Indicate the format to use
</p>
<p><var>out</var>: Newly allocated datum with null terminated string.
</p>
<p>This function will pretty print public key information, suitable for
display to a human.
</p>
<p>Only <code>GNUTLS_CRT_PRINT_FULL</code>  and <code>GNUTLS_CRT_PRINT_FULL_NUMBERS</code> 
are implemented.
</p>
<p>The output  <code>out</code> needs to be deallocated using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.1.5
</p></dd></dl>

<a name="gnutls_005fpubkey_005fset_005fkey_005fusage-1"></a>
<h4 class="subheading">gnutls_pubkey_set_key_usage</h4>
<a name="gnutls_005fpubkey_005fset_005fkey_005fusage"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fset_005fkey_005fusage"></a>Function: <em>int</em> <strong>gnutls_pubkey_set_key_usage</strong> <em>(gnutls_pubkey_t <var>key</var>, unsigned int <var>usage</var>)</em></dt>
<dd><p><var>key</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>usage</var>: an ORed sequence of the GNUTLS_KEY_* elements.
</p>
<p>This function will set the key usage flags of the public key. This
is only useful if the key is to be exported to a certificate or
certificate request.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fset_005fpin_005ffunction-1"></a>
<h4 class="subheading">gnutls_pubkey_set_pin_function</h4>
<a name="gnutls_005fpubkey_005fset_005fpin_005ffunction"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fset_005fpin_005ffunction"></a>Function: <em>void</em> <strong>gnutls_pubkey_set_pin_function</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_pin_callback_t <var>fn</var>, void * <var>userdata</var>)</em></dt>
<dd><p><var>key</var>: A key of type <code>gnutls_pubkey_t</code> 
</p>
<p><var>fn</var>: the callback
</p>
<p><var>userdata</var>: data associated with the callback
</p>
<p>This function will set a callback function to be used when
required to access the object. This function overrides any other
global PIN functions.
</p>
<p>Note that this function must be called right after initialization
to have effect.
</p>
<p><strong>Since:</strong> 3.1.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fverify_005fdata2-1"></a>
<h4 class="subheading">gnutls_pubkey_verify_data2</h4>
<a name="gnutls_005fpubkey_005fverify_005fdata2"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fverify_005fdata2-1"></a>Function: <em>int</em> <strong>gnutls_pubkey_verify_data2</strong> <em>(gnutls_pubkey_t <var>pubkey</var>, gnutls_sign_algorithm_t <var>algo</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>data</var>, const gnutls_datum_t * <var>signature</var>)</em></dt>
<dd><p><var>pubkey</var>: Holds the public key
</p>
<p><var>algo</var>: The signature algorithm used
</p>
<p><var>flags</var>: Zero or an OR list of <code>gnutls_certificate_verify_flags</code> 
</p>
<p><var>data</var>: holds the signed data
</p>
<p><var>signature</var>: contains the signature
</p>
<p>This function will verify the given signed data, using the
parameters from the certificate.
</p>
<p><strong>Returns:</strong> In case of a verification failure <code>GNUTLS_E_PK_SIG_VERIFY_FAILED</code>  
is returned, and zero or positive code on success. For known to be insecure
signatures this function will return <code>GNUTLS_E_INSUFFICIENT_SECURITY</code>  unless
the flag <code>GNUTLS_VERIFY_ALLOW_BROKEN</code>  is specified.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fverify_005fhash2-1"></a>
<h4 class="subheading">gnutls_pubkey_verify_hash2</h4>
<a name="gnutls_005fpubkey_005fverify_005fhash2"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fverify_005fhash2-1"></a>Function: <em>int</em> <strong>gnutls_pubkey_verify_hash2</strong> <em>(gnutls_pubkey_t <var>key</var>, gnutls_sign_algorithm_t <var>algo</var>, unsigned int <var>flags</var>, const gnutls_datum_t * <var>hash</var>, const gnutls_datum_t * <var>signature</var>)</em></dt>
<dd><p><var>key</var>: Holds the public key
</p>
<p><var>algo</var>: The signature algorithm used
</p>
<p><var>flags</var>: Zero or an OR list of <code>gnutls_certificate_verify_flags</code> 
</p>
<p><var>hash</var>: holds the hash digest to be verified
</p>
<p><var>signature</var>: contains the signature
</p>
<p>This function will verify the given signed digest, using the
parameters from the public key. Note that unlike <code>gnutls_privkey_sign_hash()</code> ,
this function accepts a signature algorithm instead of a digest algorithm.
You can use <code>gnutls_pk_to_sign()</code>  to get the appropriate value.
</p>
<p><strong>Returns:</strong> In case of a verification failure <code>GNUTLS_E_PK_SIG_VERIFY_FAILED</code>  
is returned, and zero or positive code on success.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fpubkey_005fverify_005fparams-1"></a>
<h4 class="subheading">gnutls_pubkey_verify_params</h4>
<a name="gnutls_005fpubkey_005fverify_005fparams"></a><dl>
<dt><a name="index-gnutls_005fpubkey_005fverify_005fparams"></a>Function: <em>int</em> <strong>gnutls_pubkey_verify_params</strong> <em>(gnutls_pubkey_t <var>key</var>)</em></dt>
<dd><p><var>key</var>: should contain a <code>gnutls_pubkey_t</code>  type
</p>
<p>This function will verify the private key parameters.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.3.0
</p></dd></dl>

<a name="gnutls_005fregister_005fcustom_005furl-1"></a>
<h4 class="subheading">gnutls_register_custom_url</h4>
<a name="gnutls_005fregister_005fcustom_005furl"></a><dl>
<dt><a name="index-gnutls_005fregister_005fcustom_005furl-1"></a>Function: <em>int</em> <strong>gnutls_register_custom_url</strong> <em>(const gnutls_custom_url_st * <var>st</var>)</em></dt>
<dd><p><var>st</var>: A <code>gnutls_custom_url_st</code>  structure
</p>
<p>Register a custom URL. This will affect the following functions:
<code>gnutls_url_is_supported()</code> , <code>gnutls_privkey_import_url()</code> ,
gnutls_pubkey_import_url, <code>gnutls_x509_crt_import_url()</code>  
and all functions that depend on
them, e.g., <code>gnutls_certificate_set_x509_key_file2()</code> .
</p>
<p>The provided structure and callback functions must be valid throughout
the lifetime of the process. The registration of an existing URL type
will fail with <code>GNUTLS_E_INVALID_REQUEST</code> .
</p>
<p>This function is not thread safe.
</p>
<p><strong>Returns:</strong> returns zero if the given structure was imported or a negative value otherwise.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fsystem_005fkey_005fadd_005fx509-1"></a>
<h4 class="subheading">gnutls_system_key_add_x509</h4>
<a name="gnutls_005fsystem_005fkey_005fadd_005fx509"></a><dl>
<dt><a name="index-gnutls_005fsystem_005fkey_005fadd_005fx509"></a>Function: <em>int</em> <strong>gnutls_system_key_add_x509</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_privkey_t <var>privkey</var>, const char * <var>label</var>, char ** <var>cert_url</var>, char ** <var>key_url</var>)</em></dt>
<dd><p><var>crt</var>: the certificate to be added
</p>
<p><var>privkey</var>: the key to be added
</p>
<p><var>label</var>: the friendly name to describe the key
</p>
<p><var>cert_url</var>: if non-NULL it will contain an allocated value with the certificate URL
</p>
<p><var>key_url</var>: if non-NULL it will contain an allocated value with the key URL
</p>
<p>This function will added the given key and certificate pair,
to the system list.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fsystem_005fkey_005fdelete-1"></a>
<h4 class="subheading">gnutls_system_key_delete</h4>
<a name="gnutls_005fsystem_005fkey_005fdelete"></a><dl>
<dt><a name="index-gnutls_005fsystem_005fkey_005fdelete"></a>Function: <em>int</em> <strong>gnutls_system_key_delete</strong> <em>(const char * <var>cert_url</var>, const char * <var>key_url</var>)</em></dt>
<dd><p><var>cert_url</var>: the URL of the certificate
</p>
<p><var>key_url</var>: the URL of the key
</p>
<p>This function will delete the key and certificate pair.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fsystem_005fkey_005fiter_005fdeinit-1"></a>
<h4 class="subheading">gnutls_system_key_iter_deinit</h4>
<a name="gnutls_005fsystem_005fkey_005fiter_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fsystem_005fkey_005fiter_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_system_key_iter_deinit</strong> <em>(gnutls_system_key_iter_t <var>iter</var>)</em></dt>
<dd><p><var>iter</var>: an iterator of system keys
</p>
<p>This function will deinitialize the iterator.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fsystem_005fkey_005fiter_005fget_005finfo-1"></a>
<h4 class="subheading">gnutls_system_key_iter_get_info</h4>
<a name="gnutls_005fsystem_005fkey_005fiter_005fget_005finfo"></a><dl>
<dt><a name="index-gnutls_005fsystem_005fkey_005fiter_005fget_005finfo-1"></a>Function: <em>int</em> <strong>gnutls_system_key_iter_get_info</strong> <em>(gnutls_system_key_iter_t * <var>iter</var>, unsigned <var>cert_type</var>, char ** <var>cert_url</var>, char ** <var>key_url</var>, char ** <var>label</var>, gnutls_datum_t * <var>der</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>iter</var>: an iterator of the system keys (must be set to <code>NULL</code>  initially)
</p>
<p><var>cert_type</var>: A value of gnutls_certificate_type_t which indicates the type of certificate to look for
</p>
<p><var>cert_url</var>: The certificate URL of the pair (may be <code>NULL</code> )
</p>
<p><var>key_url</var>: The key URL of the pair (may be <code>NULL</code> )
</p>
<p><var>label</var>: The friendly name (if any) of the pair (may be <code>NULL</code> )
</p>
<p><var>der</var>: if non-NULL the DER data of the certificate
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will return on each call a certificate
and key pair URLs, as well as a label associated with them,
and the DER-encoded certificate. When the iteration is complete it will
return <code>GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE</code> .
</p>
<p>Typically  <code>cert_type</code> should be <code>GNUTLS_CRT_X509</code> .
</p>
<p>All values set are allocated and must be cleared using <code>gnutls_free()</code> ,
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fprivkey_005fsign-1"></a>
<h4 class="subheading">gnutls_x509_crl_privkey_sign</h4>
<a name="gnutls_005fx509_005fcrl_005fprivkey_005fsign"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fprivkey_005fsign-1"></a>Function: <em>int</em> <strong>gnutls_x509_crl_privkey_sign</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_t <var>issuer</var>, gnutls_privkey_t <var>issuer_key</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>issuer</var>: is the certificate of the certificate issuer
</p>
<p><var>issuer_key</var>: holds the issuer&rsquo;s private key
</p>
<p><var>dig</var>: The message digest to use. GNUTLS_DIG_SHA1 is the safe choice unless you know what you&rsquo;re doing.
</p>
<p><var>flags</var>: must be 0
</p>
<p>This function will sign the CRL with the issuer&rsquo;s private key, and
will copy the issuer&rsquo;s information into the CRL.
</p>
<p>This must be the last step in a certificate CRL since all
the previously set parameters are now signed.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p>Since 2.12.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fprivkey_005fsign-1"></a>
<h4 class="subheading">gnutls_x509_crq_privkey_sign</h4>
<a name="gnutls_005fx509_005fcrq_005fprivkey_005fsign"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fprivkey_005fsign"></a>Function: <em>int</em> <strong>gnutls_x509_crq_privkey_sign</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_privkey_t <var>key</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>key</var>: holds a private key
</p>
<p><var>dig</var>: The message digest to use, i.e., <code>GNUTLS_DIG_SHA1</code> 
</p>
<p><var>flags</var>: must be 0
</p>
<p>This function will sign the certificate request with a private key.
This must be the same key as the one used in
<code>gnutls_x509_crt_set_key()</code>  since a certificate request is self
signed.
</p>
<p>This must be the last step in a certificate request generation
since all the previously set parameters are now signed.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
<code>GNUTLS_E_ASN1_VALUE_NOT_FOUND</code>  is returned if you didn&rsquo;t set all
information in the certificate request (e.g., the version using
<code>gnutls_x509_crq_set_version()</code> ).
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fset_005fpubkey-1"></a>
<h4 class="subheading">gnutls_x509_crq_set_pubkey</h4>
<a name="gnutls_005fx509_005fcrq_005fset_005fpubkey"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fset_005fpubkey-1"></a>Function: <em>int</em> <strong>gnutls_x509_crq_set_pubkey</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_pubkey_t <var>key</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>key</var>: holds a public key
</p>
<p>This function will set the public parameters from the given public
key to the request.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fprivkey_005fsign-1"></a>
<h4 class="subheading">gnutls_x509_crt_privkey_sign</h4>
<a name="gnutls_005fx509_005fcrt_005fprivkey_005fsign"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fprivkey_005fsign"></a>Function: <em>int</em> <strong>gnutls_x509_crt_privkey_sign</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_x509_crt_t <var>issuer</var>, gnutls_privkey_t <var>issuer_key</var>, gnutls_digest_algorithm_t <var>dig</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>crt</var>: a certificate of type <code>gnutls_x509_crt_t</code> 
</p>
<p><var>issuer</var>: is the certificate of the certificate issuer
</p>
<p><var>issuer_key</var>: holds the issuer&rsquo;s private key
</p>
<p><var>dig</var>: The message digest to use, <code>GNUTLS_DIG_SHA1</code>  is a safe choice
</p>
<p><var>flags</var>: must be 0
</p>
<p>This function will sign the certificate with the issuer&rsquo;s private key, and
will copy the issuer&rsquo;s information into the certificate.
</p>
<p>This must be the last step in a certificate generation since all
the previously set parameters are now signed.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fset_005fpubkey-1"></a>
<h4 class="subheading">gnutls_x509_crt_set_pubkey</h4>
<a name="gnutls_005fx509_005fcrt_005fset_005fpubkey"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fset_005fpubkey-1"></a>Function: <em>int</em> <strong>gnutls_x509_crt_set_pubkey</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_pubkey_t <var>key</var>)</em></dt>
<dd><p><var>crt</var>: should contain a <code>gnutls_x509_crt_t</code>  type
</p>
<p><var>key</var>: holds a public key
</p>
<p>This function will set the public parameters from the given public
key to the request.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>


<hr>
<a name="DANE-API"></a>
<div class="header">
<p>
Next: <a href="#Cryptographic-API" accesskey="n" rel="next">Cryptographic API</a>, Previous: <a href="#Abstract-key-API" accesskey="p" rel="prev">Abstract key API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="DANE-API-1"></a>
<h3 class="section">E.11 DANE API</h3>

<p>The following functions are to be used for DANE certificate verification.
Their prototypes lie in <samp>gnutls/dane.h</samp>. Note that you need to link
with the <code>libgnutls-dane</code> library to use them.
</p>

<a name="dane_005fcert_005ftype_005fname-1"></a>
<h4 class="subheading">dane_cert_type_name</h4>
<a name="dane_005fcert_005ftype_005fname"></a><dl>
<dt><a name="index-dane_005fcert_005ftype_005fname"></a>Function: <em>const char *</em> <strong>dane_cert_type_name</strong> <em>(dane_cert_type_t <var>type</var>)</em></dt>
<dd><p><var>type</var>: is a DANE match type
</p>
<p>Convert a <code>dane_cert_type_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified
type, or <code>NULL</code> .
</p></dd></dl>

<a name="dane_005fcert_005fusage_005fname-1"></a>
<h4 class="subheading">dane_cert_usage_name</h4>
<a name="dane_005fcert_005fusage_005fname"></a><dl>
<dt><a name="index-dane_005fcert_005fusage_005fname"></a>Function: <em>const char *</em> <strong>dane_cert_usage_name</strong> <em>(dane_cert_usage_t <var>usage</var>)</em></dt>
<dd><p><var>usage</var>: &ndash; undescribed &ndash;
</p>
<p>Convert a <code>dane_cert_usage_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified
type, or <code>NULL</code> .
</p></dd></dl>

<a name="dane_005fmatch_005ftype_005fname-1"></a>
<h4 class="subheading">dane_match_type_name</h4>
<a name="dane_005fmatch_005ftype_005fname"></a><dl>
<dt><a name="index-dane_005fmatch_005ftype_005fname"></a>Function: <em>const char *</em> <strong>dane_match_type_name</strong> <em>(dane_match_type_t <var>type</var>)</em></dt>
<dd><p><var>type</var>: is a DANE match type
</p>
<p>Convert a <code>dane_match_type_t</code>  value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified
type, or <code>NULL</code> .
</p></dd></dl>

<a name="dane_005fquery_005fdata-1"></a>
<h4 class="subheading">dane_query_data</h4>
<a name="dane_005fquery_005fdata"></a><dl>
<dt><a name="index-dane_005fquery_005fdata"></a>Function: <em>int</em> <strong>dane_query_data</strong> <em>(dane_query_t <var>q</var>, unsigned int <var>idx</var>, unsigned int * <var>usage</var>, unsigned int * <var>type</var>, unsigned int * <var>match</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>q</var>: The query result structure
</p>
<p><var>idx</var>: The index of the query response.
</p>
<p><var>usage</var>: The certificate usage (see <code>dane_cert_usage_t</code> )
</p>
<p><var>type</var>: The certificate type (see <code>dane_cert_type_t</code> )
</p>
<p><var>match</var>: The DANE matching type (see <code>dane_match_type_t</code> )
</p>
<p><var>data</var>: The DANE data.
</p>
<p>This function will provide the DANE data from the query
response.
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="dane_005fquery_005fdeinit-1"></a>
<h4 class="subheading">dane_query_deinit</h4>
<a name="dane_005fquery_005fdeinit"></a><dl>
<dt><a name="index-dane_005fquery_005fdeinit"></a>Function: <em>void</em> <strong>dane_query_deinit</strong> <em>(dane_query_t <var>q</var>)</em></dt>
<dd><p><var>q</var>: The structure to be deinitialized
</p>
<p>This function will deinitialize a DANE query result structure.
</p></dd></dl>

<a name="dane_005fquery_005fentries-1"></a>
<h4 class="subheading">dane_query_entries</h4>
<a name="dane_005fquery_005fentries"></a><dl>
<dt><a name="index-dane_005fquery_005fentries"></a>Function: <em>unsigned int</em> <strong>dane_query_entries</strong> <em>(dane_query_t <var>q</var>)</em></dt>
<dd><p><var>q</var>: The query result structure
</p>
<p>This function will return the number of entries in a query.
</p>
<p><strong>Returns:</strong> The number of entries.
</p></dd></dl>

<a name="dane_005fquery_005fstatus-1"></a>
<h4 class="subheading">dane_query_status</h4>
<a name="dane_005fquery_005fstatus"></a><dl>
<dt><a name="index-dane_005fquery_005fstatus"></a>Function: <em>dane_query_status_t</em> <strong>dane_query_status</strong> <em>(dane_query_t <var>q</var>)</em></dt>
<dd><p><var>q</var>: The query result structure
</p>
<p>This function will return the status of the query response.
See <code>dane_query_status_t</code>  for the possible types.
</p>
<p><strong>Returns:</strong> The status type.
</p></dd></dl>

<a name="dane_005fquery_005ftlsa-1"></a>
<h4 class="subheading">dane_query_tlsa</h4>
<a name="dane_005fquery_005ftlsa"></a><dl>
<dt><a name="index-dane_005fquery_005ftlsa"></a>Function: <em>int</em> <strong>dane_query_tlsa</strong> <em>(dane_state_t <var>s</var>, dane_query_t * <var>r</var>, const char * <var>host</var>, const char * <var>proto</var>, unsigned int <var>port</var>)</em></dt>
<dd><p><var>s</var>: The DANE state structure
</p>
<p><var>r</var>: A structure to place the result
</p>
<p><var>host</var>: The host name to resolve.
</p>
<p><var>proto</var>: The protocol type (tcp, udp, etc.)
</p>
<p><var>port</var>: The service port number (eg. 443).
</p>
<p>This function will query the DNS server for the TLSA (DANE)
data for the given host.
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="dane_005fquery_005fto_005fraw_005ftlsa-1"></a>
<h4 class="subheading">dane_query_to_raw_tlsa</h4>
<a name="dane_005fquery_005fto_005fraw_005ftlsa"></a><dl>
<dt><a name="index-dane_005fquery_005fto_005fraw_005ftlsa"></a>Function: <em>int</em> <strong>dane_query_to_raw_tlsa</strong> <em>(dane_query_t <var>q</var>, unsigned int * <var>data_entries</var>, char *** <var>dane_data</var>, int ** <var>dane_data_len</var>, int * <var>secure</var>, int * <var>bogus</var>)</em></dt>
<dd><p><var>q</var>: The query result structure
</p>
<p><var>data_entries</var>: Pointer set to the number of entries in the query
</p>
<p><var>dane_data</var>: Pointer to contain an array of DNS rdata items, terminated with a NULL pointer;
caller must guarantee that the referenced data remains
valid until <code>dane_query_deinit()</code>  is called.
</p>
<p><var>dane_data_len</var>: Pointer to contain the length n bytes of the dane_data items
</p>
<p><var>secure</var>: Pointer set true if the result is validated securely, false if
validation failed or the domain queried has no security info
</p>
<p><var>bogus</var>: Pointer set true if the result was not secure due to a security failure
</p>
<p>This function will provide the DANE data from the query
response.
</p>
<p>The pointers dane_data and dane_data_len are allocated with <code>gnutls_malloc()</code> 
to contain the data from the query result structure (individual
 <code>dane_data</code> items simply point to the original data and are not allocated separately).
The returned  <code>dane_data</code> are only valid during the lifetime of  <code>q</code> .
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="dane_005fraw_005ftlsa-1"></a>
<h4 class="subheading">dane_raw_tlsa</h4>
<a name="dane_005fraw_005ftlsa"></a><dl>
<dt><a name="index-dane_005fraw_005ftlsa"></a>Function: <em>int</em> <strong>dane_raw_tlsa</strong> <em>(dane_state_t <var>s</var>, dane_query_t * <var>r</var>, char *const * <var>dane_data</var>, const int * <var>dane_data_len</var>, int <var>secure</var>, int <var>bogus</var>)</em></dt>
<dd><p><var>s</var>: The DANE state structure
</p>
<p><var>r</var>: A structure to place the result
</p>
<p><var>dane_data</var>: array of DNS rdata items, terminated with a NULL pointer;
caller must guarantee that the referenced data remains
valid until <code>dane_query_deinit()</code>  is called.
</p>
<p><var>dane_data_len</var>: the length n bytes of the dane_data items
</p>
<p><var>secure</var>: true if the result is validated securely, false if
validation failed or the domain queried has no security info
</p>
<p><var>bogus</var>: if the result was not secure (secure = 0) due to a security failure,
and the result is due to a security failure, bogus is true.
</p>
<p>This function will fill in the TLSA (DANE) structure from
the given raw DNS record data. The  <code>dane_data</code> must be valid
during the lifetime of the query.
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="dane_005fstate_005fdeinit-1"></a>
<h4 class="subheading">dane_state_deinit</h4>
<a name="dane_005fstate_005fdeinit"></a><dl>
<dt><a name="index-dane_005fstate_005fdeinit"></a>Function: <em>void</em> <strong>dane_state_deinit</strong> <em>(dane_state_t <var>s</var>)</em></dt>
<dd><p><var>s</var>: The structure to be deinitialized
</p>
<p>This function will deinitialize a DANE query structure.
</p></dd></dl>

<a name="dane_005fstate_005finit-1"></a>
<h4 class="subheading">dane_state_init</h4>
<a name="dane_005fstate_005finit"></a><dl>
<dt><a name="index-dane_005fstate_005finit"></a>Function: <em>int</em> <strong>dane_state_init</strong> <em>(dane_state_t * <var>s</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>s</var>: The structure to be initialized
</p>
<p><var>flags</var>: flags from the <code>dane_state_flags</code>  enumeration
</p>
<p>This function will initialize a DANE query structure.
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="dane_005fstate_005fset_005fdlv_005ffile-1"></a>
<h4 class="subheading">dane_state_set_dlv_file</h4>
<a name="dane_005fstate_005fset_005fdlv_005ffile"></a><dl>
<dt><a name="index-dane_005fstate_005fset_005fdlv_005ffile"></a>Function: <em>int</em> <strong>dane_state_set_dlv_file</strong> <em>(dane_state_t <var>s</var>, const char * <var>file</var>)</em></dt>
<dd><p><var>s</var>: The structure to be deinitialized
</p>
<p><var>file</var>: The file holding the DLV keys.
</p>
<p>This function will set a file with trusted keys
for DLV  (DNSSEC  Lookaside  Validation).
</p></dd></dl>

<a name="dane_005fstrerror-1"></a>
<h4 class="subheading">dane_strerror</h4>
<a name="dane_005fstrerror"></a><dl>
<dt><a name="index-dane_005fstrerror"></a>Function: <em>const char *</em> <strong>dane_strerror</strong> <em>(int <var>error</var>)</em></dt>
<dd><p><var>error</var>: is a DANE error code, a negative error code
</p>
<p>This function is similar to strerror.  The difference is that it
accepts an error number returned by a gnutls function; In case of
an unknown error a descriptive string is sent instead of <code>NULL</code> .
</p>
<p>Error codes are always a negative error code.
</p>
<p><strong>Returns:</strong> A string explaining the DANE error message.
</p></dd></dl>

<a name="dane_005fverification_005fstatus_005fprint-1"></a>
<h4 class="subheading">dane_verification_status_print</h4>
<a name="dane_005fverification_005fstatus_005fprint"></a><dl>
<dt><a name="index-dane_005fverification_005fstatus_005fprint"></a>Function: <em>int</em> <strong>dane_verification_status_print</strong> <em>(unsigned int <var>status</var>, gnutls_datum_t * <var>out</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>status</var>: The status flags to be printed
</p>
<p><var>out</var>: Newly allocated datum with (0) terminated string.
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will pretty print the status of a verification
process &ndash; eg. the one obtained by <code>dane_verify_crt()</code> .
</p>
<p>The output  <code>out</code> needs to be deallocated using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="dane_005fverify_005fcrt-1"></a>
<h4 class="subheading">dane_verify_crt</h4>
<a name="dane_005fverify_005fcrt"></a><dl>
<dt><a name="index-dane_005fverify_005fcrt-1"></a>Function: <em>int</em> <strong>dane_verify_crt</strong> <em>(dane_state_t <var>s</var>, const gnutls_datum_t * <var>chain</var>, unsigned <var>chain_size</var>, gnutls_certificate_type_t <var>chain_type</var>, const char * <var>hostname</var>, const char * <var>proto</var>, unsigned int <var>port</var>, unsigned int <var>sflags</var>, unsigned int <var>vflags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>s</var>: A DANE state structure (may be NULL)
</p>
<p><var>chain</var>: A certificate chain
</p>
<p><var>chain_size</var>: The size of the chain
</p>
<p><var>chain_type</var>: The type of the certificate chain
</p>
<p><var>hostname</var>: The hostname associated with the chain
</p>
<p><var>proto</var>: The protocol of the service connecting (e.g. tcp)
</p>
<p><var>port</var>: The port of the service connecting (e.g. 443)
</p>
<p><var>sflags</var>: Flags for the the initialization of  <code>s</code> (if NULL)
</p>
<p><var>vflags</var>: Verification flags; an OR&rsquo;ed list of <code>dane_verify_flags_t</code> .
</p>
<p><var>verify</var>: An OR&rsquo;ed list of <code>dane_verify_status_t</code> .
</p>
<p>This function will verify the given certificate chain against the
CA constrains and/or the certificate available via DANE.
If no information via DANE can be obtained the flag <code>DANE_VERIFY_NO_DANE_INFO</code> 
is set. If a DNSSEC signature is not available for the DANE
record then the verify flag <code>DANE_VERIFY_NO_DNSSEC_DATA</code>  is set.
</p>
<p>Due to the many possible options of DANE, there is no single threat
model countered. When notifying the user about DANE verification results
it may be better to mention: DANE verification did not reject the certificate,
rather than mentioning a successful DANE verication.
</p>
<p>Note that this function is designed to be run in addition to
PKIX - certificate chain - verification. To be run independently
the <code>DANE_VFLAG_ONLY_CHECK_EE_USAGE</code>  flag should be specified; 
then the function will check whether the key of the peer matches the
key advertized in the DANE entry.
</p>
<p>If the  <code>q</code> parameter is provided it will be used for caching entries.
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="dane_005fverify_005fcrt_005fraw-1"></a>
<h4 class="subheading">dane_verify_crt_raw</h4>
<a name="dane_005fverify_005fcrt_005fraw"></a><dl>
<dt><a name="index-dane_005fverify_005fcrt_005fraw"></a>Function: <em>int</em> <strong>dane_verify_crt_raw</strong> <em>(dane_state_t <var>s</var>, const gnutls_datum_t * <var>chain</var>, unsigned <var>chain_size</var>, gnutls_certificate_type_t <var>chain_type</var>, dane_query_t <var>r</var>, unsigned int <var>sflags</var>, unsigned int <var>vflags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>s</var>: A DANE state structure (may be NULL)
</p>
<p><var>chain</var>: A certificate chain
</p>
<p><var>chain_size</var>: The size of the chain
</p>
<p><var>chain_type</var>: The type of the certificate chain
</p>
<p><var>r</var>: DANE data to check against
</p>
<p><var>sflags</var>: Flags for the the initialization of  <code>s</code> (if NULL)
</p>
<p><var>vflags</var>: Verification flags; an OR&rsquo;ed list of <code>dane_verify_flags_t</code> .
</p>
<p><var>verify</var>: An OR&rsquo;ed list of <code>dane_verify_status_t</code> .
</p>
<p>This function will verify the given certificate chain against the
CA constrains and/or the certificate available via DANE.
If no information via DANE can be obtained the flag <code>DANE_VERIFY_NO_DANE_INFO</code> 
is set. If a DNSSEC signature is not available for the DANE
record then the verify flag <code>DANE_VERIFY_NO_DNSSEC_DATA</code>  is set.
</p>
<p>Due to the many possible options of DANE, there is no single threat
model countered. When notifying the user about DANE verification results
it may be better to mention: DANE verification did not reject the certificate,
rather than mentioning a successful DANE verication.
</p>
<p>Note that this function is designed to be run in addition to
PKIX - certificate chain - verification. To be run independently
the <code>DANE_VFLAG_ONLY_CHECK_EE_USAGE</code>  flag should be specified; 
then the function will check whether the key of the peer matches the
key advertized in the DANE entry.
</p>
<p>If the  <code>q</code> parameter is provided it will be used for caching entries.
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>

<a name="dane_005fverify_005fsession_005fcrt-1"></a>
<h4 class="subheading">dane_verify_session_crt</h4>
<a name="dane_005fverify_005fsession_005fcrt"></a><dl>
<dt><a name="index-dane_005fverify_005fsession_005fcrt"></a>Function: <em>int</em> <strong>dane_verify_session_crt</strong> <em>(dane_state_t <var>s</var>, gnutls_session_t <var>session</var>, const char * <var>hostname</var>, const char * <var>proto</var>, unsigned int <var>port</var>, unsigned int <var>sflags</var>, unsigned int <var>vflags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>s</var>: A DANE state structure (may be NULL)
</p>
<p><var>session</var>: A gnutls session
</p>
<p><var>hostname</var>: The hostname associated with the chain
</p>
<p><var>proto</var>: The protocol of the service connecting (e.g. tcp)
</p>
<p><var>port</var>: The port of the service connecting (e.g. 443)
</p>
<p><var>sflags</var>: Flags for the the initialization of  <code>s</code> (if NULL)
</p>
<p><var>vflags</var>: Verification flags; an OR&rsquo;ed list of <code>dane_verify_flags_t</code> .
</p>
<p><var>verify</var>: An OR&rsquo;ed list of <code>dane_verify_status_t</code> .
</p>
<p>This function will verify session&rsquo;s certificate chain against the
CA constrains and/or the certificate available via DANE.
See <code>dane_verify_crt()</code>  for more information.
</p>
<p>This will not verify the chain for validity; unless the DANE
verification is restricted to end certificates, this must be
be performed separately using <code>gnutls_certificate_verify_peers3()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p></dd></dl>


<hr>
<a name="Cryptographic-API"></a>
<div class="header">
<p>
Next: <a href="#Compatibility-API" accesskey="n" rel="next">Compatibility API</a>, Previous: <a href="#DANE-API" accesskey="p" rel="prev">DANE API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Cryptographic-API-1"></a>
<h3 class="section">E.12 Cryptographic API</h3>

<p>The following functions are to be used for low-level cryptographic operations.
Their prototypes lie in <samp>gnutls/crypto.h</samp>.
</p>

<a name="gnutls_005faead_005fcipher_005fdecrypt-1"></a>
<h4 class="subheading">gnutls_aead_cipher_decrypt</h4>
<a name="gnutls_005faead_005fcipher_005fdecrypt"></a><dl>
<dt><a name="index-gnutls_005faead_005fcipher_005fdecrypt"></a>Function: <em>int</em> <strong>gnutls_aead_cipher_decrypt</strong> <em>(gnutls_aead_cipher_hd_t <var>handle</var>, const void * <var>nonce</var>, size_t <var>nonce_len</var>, const void * <var>auth</var>, size_t <var>auth_len</var>, size_t <var>tag_size</var>, const void * <var>ctext</var>, size_t <var>ctext_len</var>, void * <var>ptext</var>, size_t * <var>ptext_len</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_aead_cipher_hd_t</code>  type.
</p>
<p><var>nonce</var>: the nonce to set
</p>
<p><var>nonce_len</var>: The length of the nonce
</p>
<p><var>auth</var>: the data to be authenticated
</p>
<p><var>auth_len</var>: The length of the data
</p>
<p><var>tag_size</var>: The size of the tag to use (use zero for the default)
</p>
<p><var>ctext</var>: the data to decrypt
</p>
<p><var>ctext_len</var>: the length of data to decrypt (includes tag size)
</p>
<p><var>ptext</var>: the decrypted data
</p>
<p><var>ptext_len</var>: the length of decrypted data (initially must hold the maximum available size)
</p>
<p>This function will decrypt the given data using the algorithm
specified by the context. This function must be provided the whole
data to be decrypted, including the tag, and will fail if the tag
verification fails.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005faead_005fcipher_005fdeinit-1"></a>
<h4 class="subheading">gnutls_aead_cipher_deinit</h4>
<a name="gnutls_005faead_005fcipher_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005faead_005fcipher_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_aead_cipher_deinit</strong> <em>(gnutls_aead_cipher_hd_t <var>handle</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_aead_cipher_hd_t</code>  type.
</p>
<p>This function will deinitialize all resources occupied by the given
authenticated-encryption context.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005faead_005fcipher_005fencrypt-1"></a>
<h4 class="subheading">gnutls_aead_cipher_encrypt</h4>
<a name="gnutls_005faead_005fcipher_005fencrypt"></a><dl>
<dt><a name="index-gnutls_005faead_005fcipher_005fencrypt"></a>Function: <em>int</em> <strong>gnutls_aead_cipher_encrypt</strong> <em>(gnutls_aead_cipher_hd_t <var>handle</var>, const void * <var>nonce</var>, size_t <var>nonce_len</var>, const void * <var>auth</var>, size_t <var>auth_len</var>, size_t <var>tag_size</var>, const void * <var>ptext</var>, size_t <var>ptext_len</var>, void * <var>ctext</var>, size_t * <var>ctext_len</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_aead_cipher_hd_t</code>  type.
</p>
<p><var>nonce</var>: the nonce to set
</p>
<p><var>nonce_len</var>: The length of the nonce
</p>
<p><var>auth</var>: the data to be authenticated
</p>
<p><var>auth_len</var>: The length of the data
</p>
<p><var>tag_size</var>: The size of the tag to use (use zero for the default)
</p>
<p><var>ptext</var>: the data to encrypt
</p>
<p><var>ptext_len</var>: The length of data to encrypt
</p>
<p><var>ctext</var>: the encrypted data
</p>
<p><var>ctext_len</var>: the length of encrypted data (initially must hold the maximum available size, including space for tag)
</p>
<p>This function will encrypt the given data using the algorithm
specified by the context. The output data will contain the
authentication tag. This function requires that 
<code>gnutls_aead_cipher_set_nonce()</code>  is called before it.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005faead_005fcipher_005finit-1"></a>
<h4 class="subheading">gnutls_aead_cipher_init</h4>
<a name="gnutls_005faead_005fcipher_005finit"></a><dl>
<dt><a name="index-gnutls_005faead_005fcipher_005finit"></a>Function: <em>int</em> <strong>gnutls_aead_cipher_init</strong> <em>(gnutls_aead_cipher_hd_t * <var>handle</var>, gnutls_cipher_algorithm_t <var>cipher</var>, const gnutls_datum_t * <var>key</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_aead_cipher_hd_t</code>  type.
</p>
<p><var>cipher</var>: the authenticated-encryption algorithm to use
</p>
<p><var>key</var>: The key to be used for encryption
</p>
<p>This function will initialize an context that can be used for
encryption/decryption of data. This will effectively use the
current crypto backend in use by gnutls or the cryptographic
accelerator in use.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fcipher_005fadd_005fauth-1"></a>
<h4 class="subheading">gnutls_cipher_add_auth</h4>
<a name="gnutls_005fcipher_005fadd_005fauth"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fadd_005fauth"></a>Function: <em>int</em> <strong>gnutls_cipher_add_auth</strong> <em>(gnutls_cipher_hd_t <var>handle</var>, const void * <var>ptext</var>, size_t <var>ptext_size</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_cipher_hd_t</code>  type
</p>
<p><var>ptext</var>: the data to be authenticated
</p>
<p><var>ptext_size</var>: the length of the data
</p>
<p>This function operates on authenticated encryption with
associated data (AEAD) ciphers and authenticate the
input data. This function can only be called once
and before any encryption operations.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fcipher_005fdecrypt-1"></a>
<h4 class="subheading">gnutls_cipher_decrypt</h4>
<a name="gnutls_005fcipher_005fdecrypt"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fdecrypt"></a>Function: <em>int</em> <strong>gnutls_cipher_decrypt</strong> <em>(gnutls_cipher_hd_t <var>handle</var>, void * <var>ctext</var>, size_t <var>ctext_len</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_cipher_hd_t</code>  type
</p>
<p><var>ctext</var>: the data to decrypt
</p>
<p><var>ctext_len</var>: the length of data to decrypt
</p>
<p>This function will decrypt the given data using the algorithm
specified by the context.
</p>
<p>Note that in AEAD ciphers, this will not check the tag. You will
need to compare the tag sent with the value returned from <code>gnutls_cipher_tag()</code> .
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fcipher_005fdecrypt2-1"></a>
<h4 class="subheading">gnutls_cipher_decrypt2</h4>
<a name="gnutls_005fcipher_005fdecrypt2"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fdecrypt2"></a>Function: <em>int</em> <strong>gnutls_cipher_decrypt2</strong> <em>(gnutls_cipher_hd_t <var>handle</var>, const void * <var>ctext</var>, size_t <var>ctext_len</var>, void * <var>ptext</var>, size_t <var>ptext_len</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_cipher_hd_t</code>  type
</p>
<p><var>ctext</var>: the data to decrypt
</p>
<p><var>ctext_len</var>: the length of data to decrypt
</p>
<p><var>ptext</var>: the decrypted data
</p>
<p><var>ptext_len</var>: the available length for decrypted data
</p>
<p>This function will decrypt the given data using the algorithm
specified by the context.
</p>
<p>Note that in AEAD ciphers, this will not check the tag. You will
need to compare the tag sent with the value returned from <code>gnutls_cipher_tag()</code> .
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fcipher_005fdeinit-1"></a>
<h4 class="subheading">gnutls_cipher_deinit</h4>
<a name="gnutls_005fcipher_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_cipher_deinit</strong> <em>(gnutls_cipher_hd_t <var>handle</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_cipher_hd_t</code>  type
</p>
<p>This function will deinitialize all resources occupied by the given
encryption context.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fcipher_005fencrypt-1"></a>
<h4 class="subheading">gnutls_cipher_encrypt</h4>
<a name="gnutls_005fcipher_005fencrypt"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fencrypt"></a>Function: <em>int</em> <strong>gnutls_cipher_encrypt</strong> <em>(gnutls_cipher_hd_t <var>handle</var>, void * <var>ptext</var>, size_t <var>ptext_len</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_cipher_hd_t</code>  type
</p>
<p><var>ptext</var>: the data to encrypt
</p>
<p><var>ptext_len</var>: the length of data to encrypt
</p>
<p>This function will encrypt the given data using the algorithm
specified by the context.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fcipher_005fencrypt2-1"></a>
<h4 class="subheading">gnutls_cipher_encrypt2</h4>
<a name="gnutls_005fcipher_005fencrypt2"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fencrypt2"></a>Function: <em>int</em> <strong>gnutls_cipher_encrypt2</strong> <em>(gnutls_cipher_hd_t <var>handle</var>, const void * <var>ptext</var>, size_t <var>ptext_len</var>, void * <var>ctext</var>, size_t <var>ctext_len</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_cipher_hd_t</code>  type
</p>
<p><var>ptext</var>: the data to encrypt
</p>
<p><var>ptext_len</var>: the length of data to encrypt
</p>
<p><var>ctext</var>: the encrypted data
</p>
<p><var>ctext_len</var>: the available length for encrypted data
</p>
<p>This function will encrypt the given data using the algorithm
specified by the context.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fcipher_005fget_005fblock_005fsize-1"></a>
<h4 class="subheading">gnutls_cipher_get_block_size</h4>
<a name="gnutls_005fcipher_005fget_005fblock_005fsize"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fget_005fblock_005fsize"></a>Function: <em>int</em> <strong>gnutls_cipher_get_block_size</strong> <em>(gnutls_cipher_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is an encryption algorithm
</p>

<p><strong>Returns:</strong> the block size of the encryption algorithm.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fcipher_005fget_005fiv_005fsize-1"></a>
<h4 class="subheading">gnutls_cipher_get_iv_size</h4>
<a name="gnutls_005fcipher_005fget_005fiv_005fsize"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fget_005fiv_005fsize"></a>Function: <em>int</em> <strong>gnutls_cipher_get_iv_size</strong> <em>(gnutls_cipher_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is an encryption algorithm
</p>
<p>Get block size for encryption algorithm.
</p>
<p><strong>Returns:</strong> block size for encryption algorithm.
</p>
<p><strong>Since:</strong> 3.2.0
</p></dd></dl>

<a name="gnutls_005fcipher_005fget_005ftag_005fsize-1"></a>
<h4 class="subheading">gnutls_cipher_get_tag_size</h4>
<a name="gnutls_005fcipher_005fget_005ftag_005fsize"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fget_005ftag_005fsize"></a>Function: <em>int</em> <strong>gnutls_cipher_get_tag_size</strong> <em>(gnutls_cipher_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is an encryption algorithm
</p>

<p><strong>Returns:</strong> the tag size of the authenticated encryption algorithm.
</p>
<p><strong>Since:</strong> 3.2.2
</p></dd></dl>

<a name="gnutls_005fcipher_005finit-1"></a>
<h4 class="subheading">gnutls_cipher_init</h4>
<a name="gnutls_005fcipher_005finit"></a><dl>
<dt><a name="index-gnutls_005fcipher_005finit"></a>Function: <em>int</em> <strong>gnutls_cipher_init</strong> <em>(gnutls_cipher_hd_t * <var>handle</var>, gnutls_cipher_algorithm_t <var>cipher</var>, const gnutls_datum_t * <var>key</var>, const gnutls_datum_t * <var>iv</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_cipher_hd_t</code>  type
</p>
<p><var>cipher</var>: the encryption algorithm to use
</p>
<p><var>key</var>: the key to be used for encryption/decryption
</p>
<p><var>iv</var>: the IV to use (if not applicable set NULL)
</p>
<p>This function will initialize the  <code>handle</code> context to be usable
for encryption/decryption of data. This will effectively use the
current crypto backend in use by gnutls or the cryptographic
accelerator in use.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fcipher_005fset_005fiv-1"></a>
<h4 class="subheading">gnutls_cipher_set_iv</h4>
<a name="gnutls_005fcipher_005fset_005fiv"></a><dl>
<dt><a name="index-gnutls_005fcipher_005fset_005fiv"></a>Function: <em>void</em> <strong>gnutls_cipher_set_iv</strong> <em>(gnutls_cipher_hd_t <var>handle</var>, void * <var>iv</var>, size_t <var>ivlen</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_cipher_hd_t</code>  type
</p>
<p><var>iv</var>: the IV to set
</p>
<p><var>ivlen</var>: the length of the IV
</p>
<p>This function will set the IV to be used for the next
encryption block.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fcipher_005ftag-1"></a>
<h4 class="subheading">gnutls_cipher_tag</h4>
<a name="gnutls_005fcipher_005ftag"></a><dl>
<dt><a name="index-gnutls_005fcipher_005ftag"></a>Function: <em>int</em> <strong>gnutls_cipher_tag</strong> <em>(gnutls_cipher_hd_t <var>handle</var>, void * <var>tag</var>, size_t <var>tag_size</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_cipher_hd_t</code>  type
</p>
<p><var>tag</var>: will hold the tag
</p>
<p><var>tag_size</var>: the length of the tag to return
</p>
<p>This function operates on authenticated encryption with
associated data (AEAD) ciphers and will return the
output tag.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 3.0
</p></dd></dl>

<a name="gnutls_005fcrypto_005fregister_005faead_005fcipher-1"></a>
<h4 class="subheading">gnutls_crypto_register_aead_cipher</h4>
<a name="gnutls_005fcrypto_005fregister_005faead_005fcipher"></a><dl>
<dt><a name="index-gnutls_005fcrypto_005fregister_005faead_005fcipher-1"></a>Function: <em>int</em> <strong>gnutls_crypto_register_aead_cipher</strong> <em>(gnutls_cipher_algorithm_t <var>algorithm</var>, int <var>priority</var>, gnutls_cipher_init_func <var>init</var>, gnutls_cipher_setkey_func <var>setkey</var>, gnutls_cipher_aead_encrypt_func <var>aead_encrypt</var>, gnutls_cipher_aead_decrypt_func <var>aead_decrypt</var>, gnutls_cipher_deinit_func <var>deinit</var>)</em></dt>
<dd><p><var>algorithm</var>: is the gnutls AEAD cipher identifier
</p>
<p><var>priority</var>: is the priority of the algorithm
</p>
<p><var>init</var>: A function which initializes the cipher
</p>
<p><var>setkey</var>: A function which sets the key of the cipher
</p>
<p><var>aead_encrypt</var>: Perform the AEAD encryption
</p>
<p><var>aead_decrypt</var>: Perform the AEAD decryption
</p>
<p><var>deinit</var>: A function which deinitializes the cipher
</p>
<p>This function will register a cipher algorithm to be used by
gnutls.  Any algorithm registered will override the included
algorithms and by convention kernel implemented algorithms have
priority of 90 and CPU-assisted of 80.  The algorithm with the lowest priority will be
used by gnutls.
</p>
<p>In the case the registered init or setkey functions return <code>GNUTLS_E_NEED_FALLBACK</code> ,
GnuTLS will attempt to use the next in priority registered cipher.
</p>
<p>The functions registered will be used with the new AEAD API introduced in
GnuTLS 3.4.0. Internally GnuTLS uses the new AEAD API.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fcrypto_005fregister_005fcipher-1"></a>
<h4 class="subheading">gnutls_crypto_register_cipher</h4>
<a name="gnutls_005fcrypto_005fregister_005fcipher"></a><dl>
<dt><a name="index-gnutls_005fcrypto_005fregister_005fcipher-1"></a>Function: <em>int</em> <strong>gnutls_crypto_register_cipher</strong> <em>(gnutls_cipher_algorithm_t <var>algorithm</var>, int <var>priority</var>, gnutls_cipher_init_func <var>init</var>, gnutls_cipher_setkey_func <var>setkey</var>, gnutls_cipher_setiv_func <var>setiv</var>, gnutls_cipher_encrypt_func <var>encrypt</var>, gnutls_cipher_decrypt_func <var>decrypt</var>, gnutls_cipher_deinit_func <var>deinit</var>)</em></dt>
<dd><p><var>algorithm</var>: is the gnutls algorithm identifier
</p>
<p><var>priority</var>: is the priority of the algorithm
</p>
<p><var>init</var>: A function which initializes the cipher
</p>
<p><var>setkey</var>: A function which sets the key of the cipher
</p>
<p><var>setiv</var>: A function which sets the nonce/IV of the cipher (non-AEAD)
</p>
<p><var>encrypt</var>: A function which performs encryption (non-AEAD)
</p>
<p><var>decrypt</var>: A function which performs decryption (non-AEAD)
</p>
<p><var>deinit</var>: A function which deinitializes the cipher
</p>
<p>This function will register a cipher algorithm to be used by
gnutls.  Any algorithm registered will override the included
algorithms and by convention kernel implemented algorithms have
priority of 90 and CPU-assisted of 80.  The algorithm with the lowest priority will be
used by gnutls.
</p>
<p>In the case the registered init or setkey functions return <code>GNUTLS_E_NEED_FALLBACK</code> ,
GnuTLS will attempt to use the next in priority registered cipher.
</p>
<p>The functions which are marked as non-AEAD they are not required when
registering a cipher to be used with the new AEAD API introduced in
GnuTLS 3.4.0. Internally GnuTLS uses the new AEAD API.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fcrypto_005fregister_005fdigest-1"></a>
<h4 class="subheading">gnutls_crypto_register_digest</h4>
<a name="gnutls_005fcrypto_005fregister_005fdigest"></a><dl>
<dt><a name="index-gnutls_005fcrypto_005fregister_005fdigest-1"></a>Function: <em>int</em> <strong>gnutls_crypto_register_digest</strong> <em>(gnutls_digest_algorithm_t <var>algorithm</var>, int <var>priority</var>, gnutls_digest_init_func <var>init</var>, gnutls_digest_hash_func <var>hash</var>, gnutls_digest_output_func <var>output</var>, gnutls_digest_deinit_func <var>deinit</var>, gnutls_digest_fast_func <var>hash_fast</var>)</em></dt>
<dd><p><var>algorithm</var>: is the gnutls digest identifier
</p>
<p><var>priority</var>: is the priority of the algorithm
</p>
<p><var>init</var>: A function which initializes the digest
</p>
<p><var>hash</var>: Perform the hash operation
</p>
<p><var>output</var>: Provide the output of the digest
</p>
<p><var>deinit</var>: A function which deinitializes the digest
</p>
<p><var>hash_fast</var>: Perform the digest operation in one go
</p>
<p>This function will register a digest algorithm to be used by gnutls.
Any algorithm registered will override the included algorithms and
by convention kernel implemented algorithms have priority of 90
and CPU-assisted of 80.
The algorithm with the lowest priority will be used by gnutls.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fcrypto_005fregister_005fmac-1"></a>
<h4 class="subheading">gnutls_crypto_register_mac</h4>
<a name="gnutls_005fcrypto_005fregister_005fmac"></a><dl>
<dt><a name="index-gnutls_005fcrypto_005fregister_005fmac-1"></a>Function: <em>int</em> <strong>gnutls_crypto_register_mac</strong> <em>(gnutls_mac_algorithm_t <var>algorithm</var>, int <var>priority</var>, gnutls_mac_init_func <var>init</var>, gnutls_mac_setkey_func <var>setkey</var>, gnutls_mac_setnonce_func <var>setnonce</var>, gnutls_mac_hash_func <var>hash</var>, gnutls_mac_output_func <var>output</var>, gnutls_mac_deinit_func <var>deinit</var>, gnutls_mac_fast_func <var>hash_fast</var>)</em></dt>
<dd><p><var>algorithm</var>: is the gnutls MAC identifier
</p>
<p><var>priority</var>: is the priority of the algorithm
</p>
<p><var>init</var>: A function which initializes the MAC
</p>
<p><var>setkey</var>: A function which sets the key of the MAC
</p>
<p><var>setnonce</var>: A function which sets the nonce for the mac (may be <code>NULL</code>  for common MAC algorithms)
</p>
<p><var>hash</var>: Perform the hash operation
</p>
<p><var>output</var>: Provide the output of the MAC
</p>
<p><var>deinit</var>: A function which deinitializes the MAC
</p>
<p><var>hash_fast</var>: Perform the MAC operation in one go
</p>
<p>This function will register a MAC algorithm to be used by gnutls.
Any algorithm registered will override the included algorithms and
by convention kernel implemented algorithms have priority of 90
and CPU-assisted of 80.
The algorithm with the lowest priority will be used by gnutls.
</p>
<p><strong>Returns:</strong> <code>GNUTLS_E_SUCCESS</code>  on success, otherwise a negative error code.
</p>
<p><strong>Since:</strong> 3.4.0
</p></dd></dl>

<a name="gnutls_005fhash-1"></a>
<h4 class="subheading">gnutls_hash</h4>
<a name="gnutls_005fhash"></a><dl>
<dt><a name="index-gnutls_005fhash"></a>Function: <em>int</em> <strong>gnutls_hash</strong> <em>(gnutls_hash_hd_t <var>handle</var>, const void * <var>ptext</var>, size_t <var>ptext_len</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_hash_hd_t</code>  type
</p>
<p><var>ptext</var>: the data to hash
</p>
<p><var>ptext_len</var>: the length of data to hash
</p>
<p>This function will hash the given data using the algorithm
specified by the context.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fhash_005fdeinit-1"></a>
<h4 class="subheading">gnutls_hash_deinit</h4>
<a name="gnutls_005fhash_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fhash_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_hash_deinit</strong> <em>(gnutls_hash_hd_t <var>handle</var>, void * <var>digest</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_hash_hd_t</code>  type
</p>
<p><var>digest</var>: is the output value of the hash
</p>
<p>This function will deinitialize all resources occupied by
the given hash context.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fhash_005ffast-1"></a>
<h4 class="subheading">gnutls_hash_fast</h4>
<a name="gnutls_005fhash_005ffast"></a><dl>
<dt><a name="index-gnutls_005fhash_005ffast"></a>Function: <em>int</em> <strong>gnutls_hash_fast</strong> <em>(gnutls_digest_algorithm_t <var>algorithm</var>, const void * <var>ptext</var>, size_t <var>ptext_len</var>, void * <var>digest</var>)</em></dt>
<dd><p><var>algorithm</var>: the hash algorithm to use
</p>
<p><var>ptext</var>: the data to hash
</p>
<p><var>ptext_len</var>: the length of data to hash
</p>
<p><var>digest</var>: is the output value of the hash
</p>
<p>This convenience function will hash the given data and return output
on a single call.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fhash_005fget_005flen-1"></a>
<h4 class="subheading">gnutls_hash_get_len</h4>
<a name="gnutls_005fhash_005fget_005flen"></a><dl>
<dt><a name="index-gnutls_005fhash_005fget_005flen"></a>Function: <em>int</em> <strong>gnutls_hash_get_len</strong> <em>(gnutls_digest_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: the hash algorithm to use
</p>
<p>This function will return the length of the output data
of the given hash algorithm.
</p>
<p><strong>Returns:</strong> The length or zero on error.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fhash_005finit-1"></a>
<h4 class="subheading">gnutls_hash_init</h4>
<a name="gnutls_005fhash_005finit"></a><dl>
<dt><a name="index-gnutls_005fhash_005finit"></a>Function: <em>int</em> <strong>gnutls_hash_init</strong> <em>(gnutls_hash_hd_t * <var>dig</var>, gnutls_digest_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>dig</var>: is a <code>gnutls_hash_hd_t</code>  type
</p>
<p><var>algorithm</var>: the hash algorithm to use
</p>
<p>This function will initialize an context that can be used to
produce a Message Digest of data.  This will effectively use the
current crypto backend in use by gnutls or the cryptographic
accelerator in use.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fhash_005foutput-1"></a>
<h4 class="subheading">gnutls_hash_output</h4>
<a name="gnutls_005fhash_005foutput"></a><dl>
<dt><a name="index-gnutls_005fhash_005foutput"></a>Function: <em>void</em> <strong>gnutls_hash_output</strong> <em>(gnutls_hash_hd_t <var>handle</var>, void * <var>digest</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_hash_hd_t</code>  type
</p>
<p><var>digest</var>: is the output value of the hash
</p>
<p>This function will output the current hash value
and reset the state of the hash.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fhmac-1"></a>
<h4 class="subheading">gnutls_hmac</h4>
<a name="gnutls_005fhmac"></a><dl>
<dt><a name="index-gnutls_005fhmac"></a>Function: <em>int</em> <strong>gnutls_hmac</strong> <em>(gnutls_hmac_hd_t <var>handle</var>, const void * <var>ptext</var>, size_t <var>ptext_len</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_hmac_hd_t</code>  type
</p>
<p><var>ptext</var>: the data to hash
</p>
<p><var>ptext_len</var>: the length of data to hash
</p>
<p>This function will hash the given data using the algorithm
specified by the context.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fhmac_005fdeinit-1"></a>
<h4 class="subheading">gnutls_hmac_deinit</h4>
<a name="gnutls_005fhmac_005fdeinit"></a><dl>
<dt><a name="index-gnutls_005fhmac_005fdeinit"></a>Function: <em>void</em> <strong>gnutls_hmac_deinit</strong> <em>(gnutls_hmac_hd_t <var>handle</var>, void * <var>digest</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_hmac_hd_t</code>  type
</p>
<p><var>digest</var>: is the output value of the MAC
</p>
<p>This function will deinitialize all resources occupied by
the given hmac context.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fhmac_005ffast-1"></a>
<h4 class="subheading">gnutls_hmac_fast</h4>
<a name="gnutls_005fhmac_005ffast"></a><dl>
<dt><a name="index-gnutls_005fhmac_005ffast"></a>Function: <em>int</em> <strong>gnutls_hmac_fast</strong> <em>(gnutls_mac_algorithm_t <var>algorithm</var>, const void * <var>key</var>, size_t <var>keylen</var>, const void * <var>ptext</var>, size_t <var>ptext_len</var>, void * <var>digest</var>)</em></dt>
<dd><p><var>algorithm</var>: the hash algorithm to use
</p>
<p><var>key</var>: the key to use
</p>
<p><var>keylen</var>: the length of the key
</p>
<p><var>ptext</var>: the data to hash
</p>
<p><var>ptext_len</var>: the length of data to hash
</p>
<p><var>digest</var>: is the output value of the hash
</p>
<p>This convenience function will hash the given data and return output
on a single call.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fhmac_005fget_005flen-1"></a>
<h4 class="subheading">gnutls_hmac_get_len</h4>
<a name="gnutls_005fhmac_005fget_005flen"></a><dl>
<dt><a name="index-gnutls_005fhmac_005fget_005flen"></a>Function: <em>int</em> <strong>gnutls_hmac_get_len</strong> <em>(gnutls_mac_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: the hmac algorithm to use
</p>
<p>This function will return the length of the output data
of the given hmac algorithm.
</p>
<p><strong>Returns:</strong> The length or zero on error.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fhmac_005finit-1"></a>
<h4 class="subheading">gnutls_hmac_init</h4>
<a name="gnutls_005fhmac_005finit"></a><dl>
<dt><a name="index-gnutls_005fhmac_005finit"></a>Function: <em>int</em> <strong>gnutls_hmac_init</strong> <em>(gnutls_hmac_hd_t * <var>dig</var>, gnutls_mac_algorithm_t <var>algorithm</var>, const void * <var>key</var>, size_t <var>keylen</var>)</em></dt>
<dd><p><var>dig</var>: is a <code>gnutls_hmac_hd_t</code>  type
</p>
<p><var>algorithm</var>: the HMAC algorithm to use
</p>
<p><var>key</var>: the key to be used for encryption
</p>
<p><var>keylen</var>: the length of the key
</p>
<p>This function will initialize an context that can be used to
produce a Message Authentication Code (MAC) of data.  This will
effectively use the current crypto backend in use by gnutls or the
cryptographic accelerator in use.
</p>
<p>Note that despite the name of this function, it can be used
for other MAC algorithms than HMAC.
</p>
<p><strong>Returns:</strong> Zero or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fhmac_005foutput-1"></a>
<h4 class="subheading">gnutls_hmac_output</h4>
<a name="gnutls_005fhmac_005foutput"></a><dl>
<dt><a name="index-gnutls_005fhmac_005foutput"></a>Function: <em>void</em> <strong>gnutls_hmac_output</strong> <em>(gnutls_hmac_hd_t <var>handle</var>, void * <var>digest</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_hmac_hd_t</code>  type
</p>
<p><var>digest</var>: is the output value of the MAC
</p>
<p>This function will output the current MAC value
and reset the state of the MAC.
</p>
<p><strong>Since:</strong> 2.10.0
</p></dd></dl>

<a name="gnutls_005fhmac_005fset_005fnonce-1"></a>
<h4 class="subheading">gnutls_hmac_set_nonce</h4>
<a name="gnutls_005fhmac_005fset_005fnonce"></a><dl>
<dt><a name="index-gnutls_005fhmac_005fset_005fnonce"></a>Function: <em>void</em> <strong>gnutls_hmac_set_nonce</strong> <em>(gnutls_hmac_hd_t <var>handle</var>, const void * <var>nonce</var>, size_t <var>nonce_len</var>)</em></dt>
<dd><p><var>handle</var>: is a <code>gnutls_hmac_hd_t</code>  type
</p>
<p><var>nonce</var>: the data to set as nonce
</p>
<p><var>nonce_len</var>: the length of data
</p>
<p>This function will set the nonce in the MAC algorithm.
</p>
<p><strong>Since:</strong> 3.2.0
</p></dd></dl>

<a name="gnutls_005fmac_005fget_005fnonce_005fsize-1"></a>
<h4 class="subheading">gnutls_mac_get_nonce_size</h4>
<a name="gnutls_005fmac_005fget_005fnonce_005fsize"></a><dl>
<dt><a name="index-gnutls_005fmac_005fget_005fnonce_005fsize"></a>Function: <em>size_t</em> <strong>gnutls_mac_get_nonce_size</strong> <em>(gnutls_mac_algorithm_t <var>algorithm</var>)</em></dt>
<dd><p><var>algorithm</var>: is an encryption algorithm
</p>
<p>Returns the size of the nonce used by the MAC in TLS.
</p>
<p><strong>Returns:</strong> length (in bytes) of the given MAC nonce size, or 0.
</p>
<p><strong>Since:</strong> 3.2.0
</p></dd></dl>

<a name="gnutls_005frnd-1"></a>
<h4 class="subheading">gnutls_rnd</h4>
<a name="gnutls_005frnd"></a><dl>
<dt><a name="index-gnutls_005frnd-1"></a>Function: <em>int</em> <strong>gnutls_rnd</strong> <em>(gnutls_rnd_level_t <var>level</var>, void * <var>data</var>, size_t <var>len</var>)</em></dt>
<dd><p><var>level</var>: a security level
</p>
<p><var>data</var>: place to store random bytes
</p>
<p><var>len</var>: The requested size
</p>
<p>This function will generate random data and store it to output
buffer.
</p>
<p>This function is thread-safe and also fork-safe.
</p>
<p><strong>Returns:</strong> Zero on success, or a negative error code on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005frnd_005frefresh-1"></a>
<h4 class="subheading">gnutls_rnd_refresh</h4>
<a name="gnutls_005frnd_005frefresh"></a><dl>
<dt><a name="index-gnutls_005frnd_005frefresh"></a>Function: <em>void</em> <strong>gnutls_rnd_refresh</strong> <em>( <var>void</var>)</em></dt>
<dd>
<p>This function refreshes the random generator state.
That is the current precise time, CPU usage, and
other values are input into its state.
</p>
<p>On a slower rate input from /dev/urandom is mixed too.
</p>
<p><strong>Since:</strong> 3.1.7
</p></dd></dl>


<hr>
<a name="Compatibility-API"></a>
<div class="header">
<p>
Previous: <a href="#Cryptographic-API" accesskey="p" rel="prev">Cryptographic API</a>, Up: <a href="#API-reference" accesskey="u" rel="up">API reference</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Compatibility-API-1"></a>
<h3 class="section">E.13 Compatibility API</h3>

<p>The following functions are carried over from old GnuTLS released. They might be removed at a later version.
Their prototypes lie in <samp>gnutls/compat.h</samp>.
</p>

<a name="gnutls_005fglobal_005fset_005fmem_005ffunctions-1"></a>
<h4 class="subheading">gnutls_global_set_mem_functions</h4>
<a name="gnutls_005fglobal_005fset_005fmem_005ffunctions"></a><dl>
<dt><a name="index-gnutls_005fglobal_005fset_005fmem_005ffunctions"></a>Function: <em>void</em> <strong>gnutls_global_set_mem_functions</strong> <em>(gnutls_alloc_function <var>alloc_func</var>, gnutls_alloc_function <var>secure_alloc_func</var>, gnutls_is_secure_function <var>is_secure_func</var>, gnutls_realloc_function <var>realloc_func</var>, gnutls_free_function <var>free_func</var>)</em></dt>
<dd><p><var>alloc_func</var>: it&rsquo;s the default memory allocation function. Like <code>malloc()</code> .
</p>
<p><var>secure_alloc_func</var>: This is the memory allocation function that will be used for sensitive data.
</p>
<p><var>is_secure_func</var>: a function that returns 0 if the memory given is not secure. May be NULL.
</p>
<p><var>realloc_func</var>: A realloc function
</p>
<p><var>free_func</var>: The function that frees allocated data. Must accept a NULL pointer.
</p>

<p><strong>Deprecated:</strong> since 3.3.0 it is no longer possible to replace the internally used 
memory allocation functions
</p>
<p>This is the function where you set the memory allocation functions
gnutls is going to use. By default the libc&rsquo;s allocation functions
(<code>malloc()</code> , <code>free()</code> ), are used by gnutls, to allocate both sensitive
and not sensitive data.  This function is provided to set the
memory allocation functions to something other than the defaults
</p>
<p>This function must be called before <code>gnutls_global_init()</code>  is called.
This function is not thread safe.
</p></dd></dl>

<a name="gnutls_005fopenpgp_005fprivkey_005fsign_005fhash-1"></a>
<h4 class="subheading">gnutls_openpgp_privkey_sign_hash</h4>
<a name="gnutls_005fopenpgp_005fprivkey_005fsign_005fhash"></a><dl>
<dt><a name="index-gnutls_005fopenpgp_005fprivkey_005fsign_005fhash"></a>Function: <em>int</em> <strong>gnutls_openpgp_privkey_sign_hash</strong> <em>(gnutls_openpgp_privkey_t <var>key</var>, const gnutls_datum_t * <var>hash</var>, gnutls_datum_t * <var>signature</var>)</em></dt>
<dd><p><var>key</var>: Holds the key
</p>
<p><var>hash</var>: holds the data to be signed
</p>
<p><var>signature</var>: will contain newly allocated signature
</p>
<p>This function will sign the given hash using the private key.  You
should use <code>gnutls_openpgp_privkey_set_preferred_key_id()</code>  before
calling this function to set the subkey to use.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Deprecated:</strong> Use <code>gnutls_privkey_sign_hash()</code>  instead.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrl_005fsign-1"></a>
<h4 class="subheading">gnutls_x509_crl_sign</h4>
<a name="gnutls_005fx509_005fcrl_005fsign"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrl_005fsign"></a>Function: <em>int</em> <strong>gnutls_x509_crl_sign</strong> <em>(gnutls_x509_crl_t <var>crl</var>, gnutls_x509_crt_t <var>issuer</var>, gnutls_x509_privkey_t <var>issuer_key</var>)</em></dt>
<dd><p><var>crl</var>: should contain a gnutls_x509_crl_t type
</p>
<p><var>issuer</var>: is the certificate of the certificate issuer
</p>
<p><var>issuer_key</var>: holds the issuer&rsquo;s private key
</p>
<p>This function is the same a <code>gnutls_x509_crl_sign2()</code>  with no flags, and
SHA1 as the hash algorithm.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Deprecated:</strong> Use <code>gnutls_x509_crl_privkey_sign()</code> .
</p></dd></dl>

<a name="gnutls_005fx509_005fcrq_005fsign-1"></a>
<h4 class="subheading">gnutls_x509_crq_sign</h4>
<a name="gnutls_005fx509_005fcrq_005fsign"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrq_005fsign"></a>Function: <em>int</em> <strong>gnutls_x509_crq_sign</strong> <em>(gnutls_x509_crq_t <var>crq</var>, gnutls_x509_privkey_t <var>key</var>)</em></dt>
<dd><p><var>crq</var>: should contain a <code>gnutls_x509_crq_t</code>  type
</p>
<p><var>key</var>: holds a private key
</p>
<p>This function is the same a <code>gnutls_x509_crq_sign2()</code>  with no flags,
and SHA1 as the hash algorithm.
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p><strong>Deprecated:</strong> Use <code>gnutls_x509_crq_privkey_sign()</code>  instead.
</p></dd></dl>

<a name="gnutls_005fx509_005fcrt_005fget_005fpreferred_005fhash_005falgorithm-1"></a>
<h4 class="subheading">gnutls_x509_crt_get_preferred_hash_algorithm</h4>
<a name="gnutls_005fx509_005fcrt_005fget_005fpreferred_005fhash_005falgorithm"></a><dl>
<dt><a name="index-gnutls_005fx509_005fcrt_005fget_005fpreferred_005fhash_005falgorithm"></a>Function: <em>int</em> <strong>gnutls_x509_crt_get_preferred_hash_algorithm</strong> <em>(gnutls_x509_crt_t <var>crt</var>, gnutls_digest_algorithm_t *           <var>hash</var>, unsigned int * <var>mand</var>)</em></dt>
<dd><p><var>crt</var>: Holds the certificate
</p>
<p><var>hash</var>: The result of the call with the hash algorithm used for signature
</p>
<p><var>mand</var>: If non-zero it means that the algorithm MUST use this hash. May be NULL.
</p>
<p>This function will read the certifcate and return the appropriate digest
algorithm to use for signing with this certificate. Some certificates (i.e.
DSA might not be able to sign without the preferred algorithm).
</p>
<p><strong>Deprecated:</strong> Please use <code>gnutls_pubkey_get_preferred_hash_algorithm()</code> .
</p>
<p><strong>Returns:</strong> the 0 if the hash algorithm is found. A negative error code is
returned on error.
</p>
<p><strong>Since:</strong> 2.12.0
</p></dd></dl>

<a name="gnutls_005fx509_005fprivkey_005fsign_005fhash-1"></a>
<h4 class="subheading">gnutls_x509_privkey_sign_hash</h4>
<a name="gnutls_005fx509_005fprivkey_005fsign_005fhash"></a><dl>
<dt><a name="index-gnutls_005fx509_005fprivkey_005fsign_005fhash"></a>Function: <em>int</em> <strong>gnutls_x509_privkey_sign_hash</strong> <em>(gnutls_x509_privkey_t <var>key</var>, const gnutls_datum_t * <var>hash</var>, gnutls_datum_t * <var>signature</var>)</em></dt>
<dd><p><var>key</var>: a key
</p>
<p><var>hash</var>: holds the data to be signed
</p>
<p><var>signature</var>: will contain newly allocated signature
</p>
<p>This function will sign the given hash using the private key. Do not
use this function directly unless you know what it is. Typical signing
requires the data to be hashed and stored in special formats 
(e.g. BER Digest-Info for RSA).
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code>  (0) is returned, otherwise a
negative error value.
</p>
<p>Deprecated in: 2.12.0
</p></dd></dl>


<hr>
<a name="Copying-Information"></a>
<div class="header">
<p>
Next: <a href="#Bibliography" accesskey="n" rel="next">Bibliography</a>, Previous: <a href="#API-reference" accesskey="p" rel="prev">API reference</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Copying-Information-1"></a>
<h2 class="appendix">Appendix F Copying Information</h2>
<a name="index-FDL_002c-GNU-Free-Documentation-License"></a>

<a name="GNU-Free-Documentation-License"></a>
<h3 class="heading">GNU Free Documentation License</h3>

<div align="center">Version 1.3, 3 November 2008
</div>

<div class="display">
<pre class="display">Copyright &copy; 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
<a href="http://fsf.org/">http://fsf.org/</a>

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
</pre></div>

<ol>
<li> PREAMBLE

<p>The purpose of this License is to make a manual, textbook, or other
functional and useful document <em>free</em> in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or noncommercially.
Secondarily, this License preserves for the author and publisher a way
to get credit for their work, while not being considered responsible
for modifications made by others.
</p>
<p>This License is a kind of &ldquo;copyleft&rdquo;, which means that derivative
works of the document must themselves be free in the same sense.  It
complements the GNU General Public License, which is a copyleft
license designed for free software.
</p>
<p>We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does.  But this License is not limited to software manuals;
it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book.  We recommend this License
principally for works whose purpose is instruction or reference.
</p>
</li><li> APPLICABILITY AND DEFINITIONS

<p>This License applies to any manual or other work, in any medium, that
contains a notice placed by the copyright holder saying it can be
distributed under the terms of this License.  Such a notice grants a
world-wide, royalty-free license, unlimited in duration, to use that
work under the conditions stated herein.  The &ldquo;Document&rdquo;, below,
refers to any such manual or work.  Any member of the public is a
licensee, and is addressed as &ldquo;you&rdquo;.  You accept the license if you
copy, modify or distribute the work in a way requiring permission
under copyright law.
</p>
<p>A &ldquo;Modified Version&rdquo; of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
</p>
<p>A &ldquo;Secondary Section&rdquo; is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document&rsquo;s overall
subject (or to related matters) and contains nothing that could fall
directly within that overall subject.  (Thus, if the Document is in
part a textbook of mathematics, a Secondary Section may not explain
any mathematics.)  The relationship could be a matter of historical
connection with the subject or with related matters, or of legal,
commercial, philosophical, ethical or political position regarding
them.
</p>
<p>The &ldquo;Invariant Sections&rdquo; are certain Secondary Sections whose titles
are designated, as being those of Invariant Sections, in the notice
that says that the Document is released under this License.  If a
section does not fit the above definition of Secondary then it is not
allowed to be designated as Invariant.  The Document may contain zero
Invariant Sections.  If the Document does not identify any Invariant
Sections then there are none.
</p>
<p>The &ldquo;Cover Texts&rdquo; are certain short passages of text that are listed,
as Front-Cover Texts or Back-Cover Texts, in the notice that says that
the Document is released under this License.  A Front-Cover Text may
be at most 5 words, and a Back-Cover Text may be at most 25 words.
</p>
<p>A &ldquo;Transparent&rdquo; copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images composed of
pixels) generic paint programs or (for drawings) some widely available
drawing editor, and that is suitable for input to text formatters or
for automatic translation to a variety of formats suitable for input
to text formatters.  A copy made in an otherwise Transparent file
format whose markup, or absence of markup, has been arranged to thwart
or discourage subsequent modification by readers is not Transparent.
An image format is not Transparent if used for any substantial amount
of text.  A copy that is not &ldquo;Transparent&rdquo; is called &ldquo;Opaque&rdquo;.
</p>
<p>Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input
format, SGML or XML using a publicly available
DTD, and standard-conforming simple HTML,
PostScript or PDF designed for human modification.  Examples
of transparent image formats include PNG, XCF and
JPG.  Opaque formats include proprietary formats that can be
read and edited only by proprietary word processors, SGML or
XML for which the DTD and/or processing tools are
not generally available, and the machine-generated HTML,
PostScript or PDF produced by some word processors for
output purposes only.
</p>
<p>The &ldquo;Title Page&rdquo; means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the material
this License requires to appear in the title page.  For works in
formats which do not have any title page as such, &ldquo;Title Page&rdquo; means
the text near the most prominent appearance of the work&rsquo;s title,
preceding the beginning of the body of the text.
</p>
<p>The &ldquo;publisher&rdquo; means any person or entity that distributes copies
of the Document to the public.
</p>
<p>A section &ldquo;Entitled XYZ&rdquo; means a named subunit of the Document whose
title either is precisely XYZ or contains XYZ in parentheses following
text that translates XYZ in another language.  (Here XYZ stands for a
specific section name mentioned below, such as &ldquo;Acknowledgements&rdquo;,
&ldquo;Dedications&rdquo;, &ldquo;Endorsements&rdquo;, or &ldquo;History&rdquo;.)  To &ldquo;Preserve the Title&rdquo;
of such a section when you modify the Document means that it remains a
section &ldquo;Entitled XYZ&rdquo; according to this definition.
</p>
<p>The Document may include Warranty Disclaimers next to the notice which
states that this License applies to the Document.  These Warranty
Disclaimers are considered to be included by reference in this
License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and has
no effect on the meaning of this License.
</p>
</li><li> VERBATIM COPYING

<p>You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License applies
to the Document are reproduced in all copies, and that you add no other
conditions whatsoever to those of this License.  You may not use
technical measures to obstruct or control the reading or further
copying of the copies you make or distribute.  However, you may accept
compensation in exchange for copies.  If you distribute a large enough
number of copies you must also follow the conditions in section 3.
</p>
<p>You may also lend copies, under the same conditions stated above, and
you may publicly display copies.
</p>
</li><li> COPYING IN QUANTITY

<p>If you publish printed copies (or copies in media that commonly have
printed covers) of the Document, numbering more than 100, and the
Document&rsquo;s license notice requires Cover Texts, you must enclose the
copies in covers that carry, clearly and legibly, all these Cover
Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
the back cover.  Both covers must also clearly and legibly identify
you as the publisher of these copies.  The front cover must present
the full title with all words of the title equally prominent and
visible.  You may add other material on the covers in addition.
Copying with changes limited to the covers, as long as they preserve
the title of the Document and satisfy these conditions, can be treated
as verbatim copying in other respects.
</p>
<p>If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto adjacent
pages.
</p>
<p>If you publish or distribute Opaque copies of the Document numbering
more than 100, you must either include a machine-readable Transparent
copy along with each Opaque copy, or state in or with each Opaque copy
a computer-network location from which the general network-using
public has access to download using public-standard network protocols
a complete Transparent copy of the Document, free of added material.
If you use the latter option, you must take reasonably prudent steps,
when you begin distribution of Opaque copies in quantity, to ensure
that this Transparent copy will remain thus accessible at the stated
location until at least one year after the last time you distribute an
Opaque copy (directly or through your agents or retailers) of that
edition to the public.
</p>
<p>It is requested, but not required, that you contact the authors of the
Document well before redistributing any large number of copies, to give
them a chance to provide you with an updated version of the Document.
</p>
</li><li> MODIFICATIONS

<p>You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License, with the Modified
Version filling the role of the Document, thus licensing distribution
and modification of the Modified Version to whoever possesses a copy
of it.  In addition, you must do these things in the Modified Version:
</p>
<ol>
<li> Use in the Title Page (and on the covers, if any) a title distinct
from that of the Document, and from those of previous versions
(which should, if there were any, be listed in the History section
of the Document).  You may use the same title as a previous version
if the original publisher of that version gives permission.

</li><li> List on the Title Page, as authors, one or more persons or entities
responsible for authorship of the modifications in the Modified
Version, together with at least five of the principal authors of the
Document (all of its principal authors, if it has fewer than five),
unless they release you from this requirement.

</li><li> State on the Title page the name of the publisher of the
Modified Version, as the publisher.

</li><li> Preserve all the copyright notices of the Document.

</li><li> Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.

</li><li> Include, immediately after the copyright notices, a license notice
giving the public permission to use the Modified Version under the
terms of this License, in the form shown in the Addendum below.

</li><li> Preserve in that license notice the full lists of Invariant Sections
and required Cover Texts given in the Document&rsquo;s license notice.

</li><li> Include an unaltered copy of this License.

</li><li> Preserve the section Entitled &ldquo;History&rdquo;, Preserve its Title, and add
to it an item stating at least the title, year, new authors, and
publisher of the Modified Version as given on the Title Page.  If
there is no section Entitled &ldquo;History&rdquo; in the Document, create one
stating the title, year, authors, and publisher of the Document as
given on its Title Page, then add an item describing the Modified
Version as stated in the previous sentence.

</li><li> Preserve the network location, if any, given in the Document for
public access to a Transparent copy of the Document, and likewise
the network locations given in the Document for previous versions
it was based on.  These may be placed in the &ldquo;History&rdquo; section.
You may omit a network location for a work that was published at
least four years before the Document itself, or if the original
publisher of the version it refers to gives permission.

</li><li> For any section Entitled &ldquo;Acknowledgements&rdquo; or &ldquo;Dedications&rdquo;, Preserve
the Title of the section, and preserve in the section all the
substance and tone of each of the contributor acknowledgements and/or
dedications given therein.

</li><li> Preserve all the Invariant Sections of the Document,
unaltered in their text and in their titles.  Section numbers
or the equivalent are not considered part of the section titles.

</li><li> Delete any section Entitled &ldquo;Endorsements&rdquo;.  Such a section
may not be included in the Modified Version.

</li><li> Do not retitle any existing section to be Entitled &ldquo;Endorsements&rdquo; or
to conflict in title with any Invariant Section.

</li><li> Preserve any Warranty Disclaimers.
</li></ol>

<p>If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no material
copied from the Document, you may at your option designate some or all
of these sections as invariant.  To do this, add their titles to the
list of Invariant Sections in the Modified Version&rsquo;s license notice.
These titles must be distinct from any other section titles.
</p>
<p>You may add a section Entitled &ldquo;Endorsements&rdquo;, provided it contains
nothing but endorsements of your Modified Version by various
parties&mdash;for example, statements of peer review or that the text has
been approved by an organization as the authoritative definition of a
standard.
</p>
<p>You may add a passage of up to five words as a Front-Cover Text, and a
passage of up to 25 words as a Back-Cover Text, to the end of the list
of Cover Texts in the Modified Version.  Only one passage of
Front-Cover Text and one of Back-Cover Text may be added by (or
through arrangements made by) any one entity.  If the Document already
includes a cover text for the same cover, previously added by you or
by arrangement made by the same entity you are acting on behalf of,
you may not add another; but you may replace the old one, on explicit
permission from the previous publisher that added the old one.
</p>
<p>The author(s) and publisher(s) of the Document do not by this License
give permission to use their names for publicity for or to assert or
imply endorsement of any Modified Version.
</p>
</li><li> COMBINING DOCUMENTS

<p>You may combine the Document with other documents released under this
License, under the terms defined in section 4 above for modified
versions, provided that you include in the combination all of the
Invariant Sections of all of the original documents, unmodified, and
list them all as Invariant Sections of your combined work in its
license notice, and that you preserve all their Warranty Disclaimers.
</p>
<p>The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy.  If there are multiple Invariant Sections with the same name but
different contents, make the title of each such section unique by
adding at the end of it, in parentheses, the name of the original
author or publisher of that section if known, or else a unique number.
Make the same adjustment to the section titles in the list of
Invariant Sections in the license notice of the combined work.
</p>
<p>In the combination, you must combine any sections Entitled &ldquo;History&rdquo;
in the various original documents, forming one section Entitled
&ldquo;History&rdquo;; likewise combine any sections Entitled &ldquo;Acknowledgements&rdquo;,
and any sections Entitled &ldquo;Dedications&rdquo;.  You must delete all
sections Entitled &ldquo;Endorsements.&rdquo;
</p>
</li><li> COLLECTIONS OF DOCUMENTS

<p>You may make a collection consisting of the Document and other documents
released under this License, and replace the individual copies of this
License in the various documents with a single copy that is included in
the collection, provided that you follow the rules of this License for
verbatim copying of each of the documents in all other respects.
</p>
<p>You may extract a single document from such a collection, and distribute
it individually under this License, provided you insert a copy of this
License into the extracted document, and follow this License in all
other respects regarding verbatim copying of that document.
</p>
</li><li> AGGREGATION WITH INDEPENDENT WORKS

<p>A compilation of the Document or its derivatives with other separate
and independent documents or works, in or on a volume of a storage or
distribution medium, is called an &ldquo;aggregate&rdquo; if the copyright
resulting from the compilation is not used to limit the legal rights
of the compilation&rsquo;s users beyond what the individual works permit.
When the Document is included in an aggregate, this License does not
apply to the other works in the aggregate which are not themselves
derivative works of the Document.
</p>
<p>If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half of
the entire aggregate, the Document&rsquo;s Cover Texts may be placed on
covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic form.
Otherwise they must appear on printed covers that bracket the whole
aggregate.
</p>
</li><li> TRANSLATION

<p>Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section 4.
Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections.  You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also include
the original English version of this License and the original versions
of those notices and disclaimers.  In case of a disagreement between
the translation and the original version of this License or a notice
or disclaimer, the original version will prevail.
</p>
<p>If a section in the Document is Entitled &ldquo;Acknowledgements&rdquo;,
&ldquo;Dedications&rdquo;, or &ldquo;History&rdquo;, the requirement (section 4) to Preserve
its Title (section 1) will typically require changing the actual
title.
</p>
</li><li> TERMINATION

<p>You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense, or distribute it is void, and
will automatically terminate your rights under this License.
</p>
<p>However, if you cease all violation of this License, then your license
from a particular copyright holder is reinstated (a) provisionally,
unless and until the copyright holder explicitly and finally
terminates your license, and (b) permanently, if the copyright holder
fails to notify you of the violation by some reasonable means prior to
60 days after the cessation.
</p>
<p>Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.
</p>
<p>Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
this License.  If your rights have been terminated and not permanently
reinstated, receipt of a copy of some or all of the same material does
not give you any rights to use it.
</p>
</li><li> FUTURE REVISIONS OF THIS LICENSE

<p>The Free Software Foundation may publish new, revised versions
of the GNU Free Documentation License from time to time.  Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.  See
<a href="http://www.gnu.org/copyleft/">http://www.gnu.org/copyleft/</a>.
</p>
<p>Each version of the License is given a distinguishing version number.
If the Document specifies that a particular numbered version of this
License &ldquo;or any later version&rdquo; applies to it, you have the option of
following the terms and conditions either of that specified version or
of any later version that has been published (not as a draft) by the
Free Software Foundation.  If the Document does not specify a version
number of this License, you may choose any version ever published (not
as a draft) by the Free Software Foundation.  If the Document
specifies that a proxy can decide which future versions of this
License can be used, that proxy&rsquo;s public statement of acceptance of a
version permanently authorizes you to choose that version for the
Document.
</p>
</li><li> RELICENSING

<p>&ldquo;Massive Multiauthor Collaboration Site&rdquo; (or &ldquo;MMC Site&rdquo;) means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works.  A
public wiki that anybody can edit is an example of such a server.  A
&ldquo;Massive Multiauthor Collaboration&rdquo; (or &ldquo;MMC&rdquo;) contained in the
site means any set of copyrightable works thus published on the MMC
site.
</p>
<p>&ldquo;CC-BY-SA&rdquo; means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
</p>
<p>&ldquo;Incorporate&rdquo; means to publish or republish a Document, in whole or
in part, as part of another Document.
</p>
<p>An MMC is &ldquo;eligible for relicensing&rdquo; if it is licensed under this
License, and if all works that were first published under this License
somewhere other than this MMC, and subsequently incorporated in whole
or in part into the MMC, (1) had no cover texts or invariant sections,
and (2) were thus incorporated prior to November 1, 2008.
</p>
<p>The operator of an MMC Site may republish an MMC contained in the site
under CC-BY-SA on the same site at any time before August 1, 2009,
provided the MMC is eligible for relicensing.
</p>
</li></ol>

<a name="ADDENDUM_003a-How-to-use-this-License-for-your-documents"></a>
<h3 class="heading">ADDENDUM: How to use this License for your documents</h3>

<p>To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and
license notices just after the title page:
</p>
<div class="example">
<pre class="example">  Copyright (C)  <var>year</var>  <var>your name</var>.
  Permission is granted to copy, distribute and/or modify this document
  under the terms of the GNU Free Documentation License, Version 1.3
  or any later version published by the Free Software Foundation;
  with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
  Texts.  A copy of the license is included in the section entitled ``GNU
  Free Documentation License''.
</pre></div>

<p>If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the &ldquo;with&hellip;Texts.&rdquo; line with this:
</p>
<div class="example">
<pre class="example">    with the Invariant Sections being <var>list their titles</var>, with
    the Front-Cover Texts being <var>list</var>, and with the Back-Cover Texts
    being <var>list</var>.
</pre></div>

<p>If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
</p>
<p>If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License,
to permit their use in free software.
</p>



<hr>
<a name="Bibliography"></a>
<div class="header">
<p>
Next: <a href="#Function-and-Data-Index" accesskey="n" rel="next">Function and Data Index</a>, Previous: <a href="#Copying-Information" accesskey="p" rel="prev">Copying Information</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Bibliography-1"></a>
<h2 class="unnumbered">Bibliography</h2>

<dl compact="compact">
<dt><a name="CBCATT"></a>[CBCATT]</dt>
<dd><p>Bodo Moeller, &quot;Security of CBC Ciphersuites in SSL/TLS: Problems and
Countermeasures&quot;, 2002, available from
<a href="http://www.openssl.org/~bodo/tls-cbc.txt">http://www.openssl.org/~bodo/tls-cbc.txt</a>.
</p>
</dd>
<dt><a name="GPGH"></a>[GPGH]</dt>
<dd><p>Mike Ashley, &quot;The GNU Privacy Handbook&quot;, 2002, available from
<a href="http://www.gnupg.org/gph/en/manual.pdf">http://www.gnupg.org/gph/en/manual.pdf</a>.
</p>
</dd>
<dt><a name="GUTPKI"></a>[GUTPKI]</dt>
<dd><p>Peter Gutmann, &quot;Everything you never wanted to know about PKI but were
forced to find out&quot;, Available from
<a href="http://www.cs.auckland.ac.nz/~pgut001/">http://www.cs.auckland.ac.nz/~pgut001/</a>.
</p>
</dd>
<dt><a name="KEYPIN"></a>[KEYPIN]</dt>
<dd><p>Chris Evans and Chris Palmer, &quot;Public Key Pinning Extension for HTTP&quot;, 
Available from <a href="http://tools.ietf.org/html/draft-ietf-websec-key-pinning-01">http://tools.ietf.org/html/draft-ietf-websec-key-pinning-01</a>.
</p>
</dd>
<dt><a name="NISTSP80057"></a>[NISTSP80057]</dt>
<dd><p>NIST Special Publication 800-57, &quot;Recommendation for Key Management -
Part 1: General (Revised)&quot;, March 2007, available from
<a href="http://csrc.nist.gov/publications/nistpubs/800-57/sp800-57-Part1-revised2_Mar08-2007.pdf">http://csrc.nist.gov/publications/nistpubs/800-57/sp800-57-Part1-revised2_Mar08-2007.pdf</a>.
</p>
</dd>
<dt><a name="RFC6125"></a>[RFC6125]</dt>
<dd><p>Peter Saint-Andre and Jeff Hodges, &quot;Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)&quot;,
March 2011, Available from
<a href="http://www.ietf.org/rfc/rfc6125.txt">http://www.ietf.org/rfc/rfc6125.txt</a>.
</p>
</dd>
<dt><a name="RFC2246"></a>[RFC2246]</dt>
<dd><p>Tim Dierks and Christopher Allen, &quot;The TLS Protocol Version 1.0&quot;,
January 1999, Available from
<a href="http://www.ietf.org/rfc/rfc2246.txt">http://www.ietf.org/rfc/rfc2246.txt</a>.
</p>
</dd>
<dt><a name="RFC4418"></a>[RFC4418]</dt>
<dd><p>Ted Krovetz, &quot;UMAC: Message Authentication Code using Universal Hashing&quot;,
March 2006, Available from
<a href="http://www.ietf.org/rfc/rfc4418.txt">http://www.ietf.org/rfc/rfc4418.txt</a>.
</p>
</dd>
<dt><a name="RFC4680"></a>[RFC4680]</dt>
<dd><p>S. Santesson, &quot;TLS Handshake Message for Supplemental Data&quot;,
September 2006, Available from
<a href="http://www.ietf.org/rfc/rfc4680.txt">http://www.ietf.org/rfc/rfc4680.txt</a>.
</p>
</dd>
<dt><a name="RFC4514"></a>[RFC4514]</dt>
<dd><p>Kurt D.  Zeilenga, &quot;Lightweight Directory Access Protocol (LDAP): String Representation of Distinguished Names&quot;,
June 2006, Available from
<a href="http://www.ietf.org/rfc/rfc4513.txt">http://www.ietf.org/rfc/rfc4513.txt</a>.
</p>
</dd>
<dt><a name="RFC4346"></a>[RFC4346]</dt>
<dd><p>Tim Dierks and Eric Rescorla, &quot;The TLS Protocol Version 1.1&quot;, Match
2006, Available from <a href="http://www.ietf.org/rfc/rfc4346.txt">http://www.ietf.org/rfc/rfc4346.txt</a>.
</p>
</dd>
<dt><a name="RFC4347"></a>[RFC4347]</dt>
<dd><p>Eric Rescorla and Nagendra Modadugu, &quot;Datagram Transport Layer Security&quot;, April
2006, Available from <a href="http://www.ietf.org/rfc/rfc4347.txt">http://www.ietf.org/rfc/rfc4347.txt</a>.
</p>
</dd>
<dt><a name="RFC5246"></a>[RFC5246]</dt>
<dd><p>Tim Dierks and Eric Rescorla, &quot;The TLS Protocol Version 1.2&quot;, August
2008, Available from <a href="http://www.ietf.org/rfc/rfc5246.txt">http://www.ietf.org/rfc/rfc5246.txt</a>.
</p>
</dd>
<dt><a name="RFC2440"></a>[RFC2440]</dt>
<dd><p>Jon Callas, Lutz Donnerhacke, Hal Finney and Rodney Thayer, &quot;OpenPGP
Message Format&quot;, November 1998, Available from
<a href="http://www.ietf.org/rfc/rfc2440.txt">http://www.ietf.org/rfc/rfc2440.txt</a>.
</p>
</dd>
<dt><a name="RFC4880"></a>[RFC4880]</dt>
<dd><p>Jon Callas, Lutz Donnerhacke, Hal Finney, David Shaw and Rodney
Thayer, &quot;OpenPGP Message Format&quot;, November 2007, Available from
<a href="http://www.ietf.org/rfc/rfc4880.txt">http://www.ietf.org/rfc/rfc4880.txt</a>.
</p>
</dd>
<dt><a name="RFC4211"></a>[RFC4211]</dt>
<dd><p>J. Schaad, &quot;Internet X.509 Public Key Infrastructure Certificate
Request Message Format (CRMF)&quot;, September 2005, Available from
<a href="http://www.ietf.org/rfc/rfc4211.txt">http://www.ietf.org/rfc/rfc4211.txt</a>.
</p>
</dd>
<dt><a name="RFC2817"></a>[RFC2817]</dt>
<dd><p>Rohit Khare and Scott Lawrence, &quot;Upgrading to TLS Within HTTP/1.1&quot;,
May 2000, Available from <a href="http://www.ietf.org/rfc/rfc2817.txt">http://www.ietf.org/rfc/rfc2817.txt</a>
</p>
</dd>
<dt><a name="RFC2818"></a>[RFC2818]</dt>
<dd><p>Eric Rescorla, &quot;HTTP Over TLS&quot;, May 2000, Available from
<a href="http://www.ietf/rfc/rfc2818.txt">http://www.ietf/rfc/rfc2818.txt</a>.
</p>
</dd>
<dt><a name="RFC2945"></a>[RFC2945]</dt>
<dd><p>Tom Wu, &quot;The SRP Authentication and Key Exchange System&quot;, September
2000, Available from <a href="http://www.ietf.org/rfc/rfc2945.txt">http://www.ietf.org/rfc/rfc2945.txt</a>.
</p>
</dd>
<dt><a name="RFC7301"></a>[RFC7301]</dt>
<dd><p>S. Friedl, A. Popov, A. Langley, E. Stephan, &quot;Transport Layer Security (TLS) Application-Layer Protocol Negotiation Extension&quot;,
July 2014, Available from <a href="http://www.ietf.org/rfc/rfc7301.txt">http://www.ietf.org/rfc/rfc7301.txt</a>.
</p>
</dd>
<dt><a name="RFC2986"></a>[RFC2986]</dt>
<dd><p>Magnus Nystrom and Burt Kaliski, &quot;PKCS 10 v1.7: Certification Request
Syntax Specification&quot;, November 2000, Available from
<a href="http://www.ietf.org/rfc/rfc2986.txt">http://www.ietf.org/rfc/rfc2986.txt</a>.
</p>
</dd>
<dt><a name="PKIX"></a>[PKIX]</dt>
<dd><p>D. Cooper, S. Santesson, S. Farrel, S. Boeyen, R. Housley, W. Polk,
&quot;Internet X.509 Public Key Infrastructure Certificate and Certificate
Revocation List (CRL) Profile&quot;, May 2008, available from
<a href="http://www.ietf.org/rfc/rfc5280.txt">http://www.ietf.org/rfc/rfc5280.txt</a>.
</p>
</dd>
<dt><a name="RFC3749"></a>[RFC3749]</dt>
<dd><p>Scott Hollenbeck, &quot;Transport Layer Security Protocol Compression
Methods&quot;, May 2004, available from
<a href="http://www.ietf.org/rfc/rfc3749.txt">http://www.ietf.org/rfc/rfc3749.txt</a>.
</p>
</dd>
<dt><a name="RFC3820"></a>[RFC3820]</dt>
<dd><p>Steven Tuecke, Von Welch, Doug Engert, Laura Pearlman, and Mary
Thompson, &quot;Internet X.509 Public Key Infrastructure (PKI) Proxy
Certificate Profile&quot;, June 2004, available from
<a href="http://www.ietf.org/rfc/rfc3820">http://www.ietf.org/rfc/rfc3820</a>.
</p>
</dd>
<dt><a name="RFC6520"></a>[RFC6520]</dt>
<dd><p>R. Seggelmann, M. Tuexen, and M. Williams, &quot;Transport Layer Security (TLS) and
Datagram Transport Layer Security (DTLS) Heartbeat Extension&quot;, February 2012, available from
<a href="http://www.ietf.org/rfc/rfc6520">http://www.ietf.org/rfc/rfc6520</a>.
</p>

</dd>
<dt><a name="RFC5746"></a>[RFC5746]</dt>
<dd><p>E. Rescorla, M. Ray, S. Dispensa, and N. Oskov, &quot;Transport Layer
Security (TLS) Renegotiation Indication Extension&quot;, February 2010,
available from <a href="http://www.ietf.org/rfc/rfc5746">http://www.ietf.org/rfc/rfc5746</a>.
</p>
</dd>
<dt><a name="RFC5280"></a>[RFC5280]</dt>
<dd><p>D. Cooper, S. Santesson, S. Farrell, S. Boeyen, R. Housley, and
W. Polk, &quot;Internet X.509 Public Key Infrastructure Certificate and
Certificate Revocation List (CRL) Profile&quot;, May 2008, available from
<a href="http://www.ietf.org/rfc/rfc5280">http://www.ietf.org/rfc/rfc5280</a>.
</p>
</dd>
<dt><a name="TLSTKT"></a>[TLSTKT]</dt>
<dd><p>Joseph Salowey, Hao Zhou, Pasi Eronen, Hannes Tschofenig, &quot;Transport
Layer Security (TLS) Session Resumption without Server-Side State&quot;,
January 2008, available from <a href="http://www.ietf.org/rfc/rfc5077">http://www.ietf.org/rfc/rfc5077</a>.
</p>
</dd>
<dt><a name="PKCS12"></a>[PKCS12]</dt>
<dd><p>RSA Laboratories, &quot;PKCS 12 v1.0: Personal Information Exchange
Syntax&quot;, June 1999, Available from <a href="http://www.rsa.com">http://www.rsa.com</a>.
</p>
</dd>
<dt><a name="PKCS11"></a>[PKCS11]</dt>
<dd><p>RSA Laboratories, &quot;PKCS #11 Base Functionality v2.30: Cryptoki – Draft 4&quot;,
July 2009, Available from <a href="http://www.rsa.com">http://www.rsa.com</a>.
</p>
</dd>
<dt><a name="RESCORLA"></a>[RESCORLA]</dt>
<dd><p>Eric Rescorla, &quot;SSL and TLS: Designing and Building Secure Systems&quot;,
2001
</p>
</dd>
<dt><a name="SELKEY"></a>[SELKEY]</dt>
<dd><p>Arjen Lenstra and Eric Verheul, &quot;Selecting Cryptographic Key Sizes&quot;,
2003, available from <a href="http://www.win.tue.nl/~klenstra/key.pdf">http://www.win.tue.nl/~klenstra/key.pdf</a>.
</p>
</dd>
<dt><a name="SSL3"></a>[SSL3]</dt>
<dd><p>Alan Freier, Philip Karlton and Paul Kocher, &quot;The Secure Sockets Layer (SSL) Protocol Version 3.0&quot;,
August 2011, Available from <a href="http://www.ietf.org/rfc/rfc6101.txt">http://www.ietf.org/rfc/rfc6101.txt</a>.
</p>
</dd>
<dt><a name="STEVENS"></a>[STEVENS]</dt>
<dd><p>Richard Stevens, &quot;UNIX Network Programming, Volume 1&quot;, Prentice Hall
PTR, January 1998
</p>
</dd>
<dt><a name="TLSEXT"></a>[TLSEXT]</dt>
<dd><p>Simon Blake-Wilson, Magnus Nystrom, David Hopwood, Jan Mikkelsen and
Tim Wright, &quot;Transport Layer Security (TLS) Extensions&quot;, June 2003,
Available from <a href="http://www.ietf.org/rfc/rfc3546.txt">http://www.ietf.org/rfc/rfc3546.txt</a>.
</p>
</dd>
<dt><a name="TLSPGP"></a>[TLSPGP]</dt>
<dd><p>Nikos Mavrogiannopoulos, &quot;Using OpenPGP keys for TLS authentication&quot;,
January 2011. Available from
<a href="http://www.ietf.org/rfc/rfc6091.txt">http://www.ietf.org/rfc/rfc6091.txt</a>.
</p>
</dd>
<dt><a name="TLSSRP"></a>[TLSSRP]</dt>
<dd><p>David Taylor, Trevor Perrin, Tom Wu and Nikos Mavrogiannopoulos,
&quot;Using SRP for TLS Authentication&quot;, November 2007. Available from
<a href="http://www.ietf.org/rfc/rfc5054.txt">http://www.ietf.org/rfc/rfc5054.txt</a>.
</p>
</dd>
<dt><a name="TLSPSK"></a>[TLSPSK]</dt>
<dd><p>Pasi Eronen and Hannes Tschofenig, &quot;Pre-shared key Ciphersuites for
TLS&quot;, December 2005, Available from
<a href="http://www.ietf.org/rfc/rfc4279.txt">http://www.ietf.org/rfc/rfc4279.txt</a>.
</p>
</dd>
<dt><a name="TOMSRP"></a>[TOMSRP]</dt>
<dd><p>Tom Wu, &quot;The Stanford SRP Authentication Project&quot;, Available at
<a href="http://srp.stanford.edu/">http://srp.stanford.edu/</a>.
</p>
</dd>
<dt><a name="WEGER"></a>[WEGER]</dt>
<dd><p>Arjen Lenstra and Xiaoyun Wang and Benne de Weger, &quot;Colliding X.509
Certificates&quot;, Cryptology ePrint Archive, Report 2005/067, Available
at <a href="http://eprint.iacr.org/">http://eprint.iacr.org/</a>.
</p>
</dd>
<dt><a name="ECRYPT"></a>[ECRYPT]</dt>
<dd><p>European Network of Excellence in Cryptology II, &quot;ECRYPT II Yearly
Report on Algorithms and Keysizes (2009-2010)&quot;, Available
at <a href="http://www.ecrypt.eu.org/documents/D.SPA.13.pdf">http://www.ecrypt.eu.org/documents/D.SPA.13.pdf</a>.
</p>
</dd>
<dt><a name="RFC5056"></a>[RFC5056]</dt>
<dd><p>N. Williams, &quot;On the Use of Channel Bindings to Secure Channels&quot;,
November 2007, available from <a href="http://www.ietf.org/rfc/rfc5056">http://www.ietf.org/rfc/rfc5056</a>.
</p>
</dd>
<dt><a name="RFC5929"></a>[RFC5929]</dt>
<dd><p>J. Altman, N. Williams, L. Zhu, &quot;Channel Bindings for TLS&quot;, July 2010,
available from <a href="http://www.ietf.org/rfc/rfc5929">http://www.ietf.org/rfc/rfc5929</a>.
</p>
</dd>
<dt><a name="PKCS11URI"></a>[PKCS11URI]</dt>
<dd><p>J. Pechanec, D. Moffat, &quot;The PKCS#11 URI Scheme&quot;, April 2015,
available from <a href="http://www.ietf.org/rfc/rfc7512">http://www.ietf.org/rfc/rfc7512</a>.
</p>
</dd>
<dt><a name="TPMURI"></a>[TPMURI]</dt>
<dd><p>C. Latze, N. Mavrogiannopoulos, &quot;The TPMKEY URI Scheme&quot;, January 2013,
Work in progress, available from <a href="http://tools.ietf.org/html/draft-mavrogiannopoulos-tpmuri-01">http://tools.ietf.org/html/draft-mavrogiannopoulos-tpmuri-01</a>.
</p>
</dd>
<dt><a name="ANDERSON"></a>[ANDERSON]</dt>
<dd><p>R. J. Anderson, &quot;Security Engineering: A Guide to Building Dependable Distributed Systems&quot;, 
John Wiley \&amp; Sons, Inc., 2001.
</p>
</dd>
<dt><a name="RFC4821"></a>[RFC4821]</dt>
<dd><p>M. Mathis, J. Heffner, &quot;Packetization Layer Path MTU Discovery&quot;, March 2007,
available from <a href="http://www.ietf.org/rfc/rfc4821.txt">http://www.ietf.org/rfc/rfc4821.txt</a>.
</p>
</dd>
<dt><a name="RFC2560"></a>[RFC2560]</dt>
<dd><p>M. Myers et al, &quot;X.509 Internet Public Key Infrastructure Online
Certificate Status Protocol - OCSP&quot;, June 1999, Available from
<a href="http://www.ietf.org/rfc/rfc2560.txt">http://www.ietf.org/rfc/rfc2560.txt</a>.
</p>
</dd>
<dt><a name="RIVESTCRL"></a>[RIVESTCRL]</dt>
<dd><p>R. L. Rivest, &quot;Can We Eliminate Certificate Revocation Lists?&quot;,
Proceedings of Financial Cryptography &rsquo;98; Springer Lecture Notes in
Computer Science No. 1465 (Rafael Hirschfeld, ed.), February 1998),
pages 178&ndash;183, available from
<a href="http://people.csail.mit.edu/rivest/Rivest-CanWeEliminateCertificateRevocationLists.pdf">http://people.csail.mit.edu/rivest/Rivest-CanWeEliminateCertificateRevocationLists.pdf</a>.
</p>
</dd>
</dl>

<hr>
<a name="Function-and-Data-Index"></a>
<div class="header">
<p>
Next: <a href="#Concept-Index" accesskey="n" rel="next">Concept Index</a>, Previous: <a href="#Bibliography" accesskey="p" rel="prev">Bibliography</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Function-and-Data-Index-1"></a>
<h2 class="unnumbered">Function and Data Index</h2>

<table><tr><th valign="top">Jump to: &nbsp; </th><td><a class="summary-letter" href="#Function-and-Data-Index_fn_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter" href="#Function-and-Data-Index_fn_letter-G"><b>G</b></a>
 &nbsp; 
</td></tr></table>
<table class="index-fn" border="0">
<tr><td></td><th align="left">Index Entry</th><td>&nbsp;</td><th align="left"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Function-and-Data-Index_fn_letter-D">D</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fcert_005ftype_005fname"><code>dane_cert_type_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fcert_005fusage_005fname"><code>dane_cert_usage_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fmatch_005ftype_005fname"><code>dane_match_type_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fquery_005fdata"><code>dane_query_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fquery_005fdeinit"><code>dane_query_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fquery_005fentries"><code>dane_query_entries</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fquery_005fstatus"><code>dane_query_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fquery_005ftlsa"><code>dane_query_tlsa</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fquery_005fto_005fraw_005ftlsa"><code>dane_query_to_raw_tlsa</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fraw_005ftlsa"><code>dane_raw_tlsa</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fstate_005fdeinit"><code>dane_state_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fstate_005finit"><code>dane_state_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fstate_005fset_005fdlv_005ffile"><code>dane_state_set_dlv_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fstrerror"><code>dane_strerror</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fverification_005fstatus_005fprint"><code>dane_verification_status_print</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fverify_005fcrt"><code>dane_verify_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-verification">Certificate verification</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fverify_005fcrt-1"><code>dane_verify_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fverify_005fcrt_005fraw"><code>dane_verify_crt_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-dane_005fverify_005fsession_005fcrt"><code>dane_verify_session_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#DANE-API">DANE API</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Function-and-Data-Index_fn_letter-G">G</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005faead_005fcipher_005fdecrypt"><code>gnutls_aead_cipher_decrypt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005faead_005fcipher_005fdeinit"><code>gnutls_aead_cipher_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005faead_005fcipher_005fencrypt"><code>gnutls_aead_cipher_encrypt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005faead_005fcipher_005finit"><code>gnutls_aead_cipher_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005falert_005fget"><code>gnutls_alert_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Handling-alerts">Handling alerts</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005falert_005fget-1"><code>gnutls_alert_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005falert_005fget_005fname"><code>gnutls_alert_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Handling-alerts">Handling alerts</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005falert_005fget_005fname-1"><code>gnutls_alert_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005falert_005fget_005fstrname"><code>gnutls_alert_get_strname</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005falert_005fsend"><code>gnutls_alert_send</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Handling-alerts">Handling alerts</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005falert_005fsend-1"><code>gnutls_alert_send</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005falert_005fsend_005fappropriate"><code>gnutls_alert_send_appropriate</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005falpn_005fget_005fselected_005fprotocol"><code>gnutls_alpn_get_selected_protocol</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005falpn_005fset_005fprotocols"><code>gnutls_alpn_set_protocols</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fanon_005fallocate_005fclient_005fcredentials"><code>gnutls_anon_allocate_client_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fanon_005fallocate_005fserver_005fcredentials"><code>gnutls_anon_allocate_server_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fanon_005ffree_005fclient_005fcredentials"><code>gnutls_anon_free_client_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fanon_005ffree_005fserver_005fcredentials"><code>gnutls_anon_free_server_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fanon_005fset_005fparams_005ffunction"><code>gnutls_anon_set_params_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fanon_005fset_005fserver_005fdh_005fparams"><code>gnutls_anon_set_server_dh_params</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fanon_005fset_005fserver_005fparams_005ffunction"><code>gnutls_anon_set_server_params_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fauth_005fclient_005fget_005ftype"><code>gnutls_auth_client_get_type</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fauth_005fget_005ftype"><code>gnutls_auth_get_type</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fauth_005fserver_005fget_005ftype"><code>gnutls_auth_server_get_type</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fbuffer_005fappend_005fdata"><code>gnutls_buffer_append_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fbye"><code>gnutls_bye</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Data-transfer-and-termination">Data transfer and termination</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fbye-1"><code>gnutls_bye</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005factivation_005ftime_005fpeers"><code>gnutls_certificate_activation_time_peers</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fallocate_005fcredentials"><code>gnutls_certificate_allocate_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fclient_005fget_005frequest_005fstatus"><code>gnutls_certificate_client_get_request_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fexpiration_005ftime_005fpeers"><code>gnutls_certificate_expiration_time_peers</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005ffree_005fcas"><code>gnutls_certificate_free_cas</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005ffree_005fca_005fnames"><code>gnutls_certificate_free_ca_names</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005ffree_005fcredentials"><code>gnutls_certificate_free_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005ffree_005fcrls"><code>gnutls_certificate_free_crls</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005ffree_005fkeys"><code>gnutls_certificate_free_keys</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fget_005fcrt_005fraw"><code>gnutls_certificate_get_crt_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fget_005fissuer"><code>gnutls_certificate_get_issuer</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fget_005fopenpgp_005fcrt"><code>gnutls_certificate_get_openpgp_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fget_005fopenpgp_005fkey"><code>gnutls_certificate_get_openpgp_key</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fget_005fours"><code>gnutls_certificate_get_ours</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fget_005fpeers"><code>gnutls_certificate_get_peers</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fget_005fpeers_005fsubkey_005fid"><code>gnutls_certificate_get_peers_subkey_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fget_005ftrust_005flist"><code>gnutls_certificate_get_trust_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fget_005fverify_005fflags"><code>gnutls_certificate_get_verify_flags</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fget_005fx509_005fcrt"><code>gnutls_certificate_get_x509_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fget_005fx509_005fkey"><code>gnutls_certificate_get_x509_key</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fsend_005fx509_005frdn_005fsequence"><code>gnutls_certificate_send_x509_rdn_sequence</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-credentials">Certificate credentials</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fsend_005fx509_005frdn_005fsequence-1"><code>gnutls_certificate_send_x509_rdn_sequence</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fserver_005fset_005frequest"><code>gnutls_certificate_server_set_request</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-credentials">Certificate credentials</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fserver_005fset_005frequest-1"><code>gnutls_certificate_server_set_request</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fdh_005fparams"><code>gnutls_certificate_set_dh_params</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fflags"><code>gnutls_certificate_set_flags</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fkey"><code>gnutls_certificate_set_key</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-credentials">Certificate credentials</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fkey-1"><code>gnutls_certificate_set_key</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005focsp_005fstatus_005frequest_005ffile"><code>gnutls_certificate_set_ocsp_status_request_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005focsp_005fstatus_005frequest_005ffunction"><code>gnutls_certificate_set_ocsp_status_request_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fopenpgp_005fkey"><code>gnutls_certificate_set_openpgp_key</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fopenpgp_005fkeyring_005ffile"><code>gnutls_certificate_set_openpgp_keyring_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-certificates">OpenPGP certificates</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fopenpgp_005fkeyring_005ffile-1"><code>gnutls_certificate_set_openpgp_keyring_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fopenpgp_005fkeyring_005fmem"><code>gnutls_certificate_set_openpgp_keyring_mem</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005ffile"><code>gnutls_certificate_set_openpgp_key_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005ffile2"><code>gnutls_certificate_set_openpgp_key_file2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005fmem"><code>gnutls_certificate_set_openpgp_key_mem</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fopenpgp_005fkey_005fmem2"><code>gnutls_certificate_set_openpgp_key_mem2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fparams_005ffunction"><code>gnutls_certificate_set_params_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Parameter-generation">Parameter generation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fparams_005ffunction-1"><code>gnutls_certificate_set_params_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fpin_005ffunction"><code>gnutls_certificate_set_pin_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-credentials">Certificate credentials</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fpin_005ffunction-1"><code>gnutls_certificate_set_pin_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fretrieve_005ffunction"><code>gnutls_certificate_set_retrieve_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fretrieve_005ffunction2"><code>gnutls_certificate_set_retrieve_function2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005ftrust_005flist"><code>gnutls_certificate_set_trust_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fverify_005fflags"><code>gnutls_certificate_set_verify_flags</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fverify_005ffunction"><code>gnutls_certificate_set_verify_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fverify_005flimits"><code>gnutls_certificate_set_verify_limits</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005fcrl"><code>gnutls_certificate_set_x509_crl</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005fcrl_005ffile"><code>gnutls_certificate_set_x509_crl_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005fcrl_005fmem"><code>gnutls_certificate_set_x509_crl_mem</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005fkey"><code>gnutls_certificate_set_x509_key</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile"><code>gnutls_certificate_set_x509_key_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005fkey_005ffile2"><code>gnutls_certificate_set_x509_key_file2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005fkey_005fmem"><code>gnutls_certificate_set_x509_key_mem</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005fkey_005fmem2"><code>gnutls_certificate_set_x509_key_mem2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005fsimple_005fpkcs12_005ffile"><code>gnutls_certificate_set_x509_simple_pkcs12_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005fsimple_005fpkcs12_005fmem"><code>gnutls_certificate_set_x509_simple_pkcs12_mem</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005fsystem_005ftrust"><code>gnutls_certificate_set_x509_system_trust</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Using-a-PKCS11-token-with-TLS">Using a PKCS11 token with TLS</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005fsystem_005ftrust-1"><code>gnutls_certificate_set_x509_system_trust</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005ftrust"><code>gnutls_certificate_set_x509_trust</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005ftrust_005fdir"><code>gnutls_certificate_set_x509_trust_dir</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005ftrust_005ffile"><code>gnutls_certificate_set_x509_trust_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fset_005fx509_005ftrust_005fmem"><code>gnutls_certificate_set_x509_trust_mem</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005ftype_005fget"><code>gnutls_certificate_type_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005ftype_005fget_005fid"><code>gnutls_certificate_type_get_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005ftype_005fget_005fname"><code>gnutls_certificate_type_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005ftype_005flist"><code>gnutls_certificate_type_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fverification_005fstatus_005fprint"><code>gnutls_certificate_verification_status_print</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fverify_005fflags"><code>gnutls_certificate_verify_flags</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-a-certificate-in-the-context-of-TLS-session">Verifying a certificate in the context of TLS session</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fverify_005fflags-1"><code>gnutls_certificate_verify_flags</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-verification">Certificate verification</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fverify_005fpeers"><code>gnutls_certificate_verify_peers</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fverify_005fpeers2"><code>gnutls_certificate_verify_peers2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcertificate_005fverify_005fpeers3"><code>gnutls_certificate_verify_peers3</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcheck_005fversion"><code>gnutls_check_version</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fadd_005fauth"><code>gnutls_cipher_add_auth</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fdecrypt"><code>gnutls_cipher_decrypt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fdecrypt2"><code>gnutls_cipher_decrypt2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fdeinit"><code>gnutls_cipher_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fencrypt"><code>gnutls_cipher_encrypt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fencrypt2"><code>gnutls_cipher_encrypt2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fget"><code>gnutls_cipher_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fget_005fblock_005fsize"><code>gnutls_cipher_get_block_size</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fget_005fid"><code>gnutls_cipher_get_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fget_005fiv_005fsize"><code>gnutls_cipher_get_iv_size</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fget_005fkey_005fsize"><code>gnutls_cipher_get_key_size</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fget_005fname"><code>gnutls_cipher_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fget_005ftag_005fsize"><code>gnutls_cipher_get_tag_size</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005finit"><code>gnutls_cipher_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005flist"><code>gnutls_cipher_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fset_005fiv"><code>gnutls_cipher_set_iv</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fsuite_005fget_005fname"><code>gnutls_cipher_suite_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005fsuite_005finfo"><code>gnutls_cipher_suite_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcipher_005ftag"><code>gnutls_cipher_tag</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcompression_005fget"><code>gnutls_compression_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcompression_005fget_005fid"><code>gnutls_compression_get_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcompression_005fget_005fname"><code>gnutls_compression_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcompression_005flist"><code>gnutls_compression_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcredentials_005fclear"><code>gnutls_credentials_clear</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcredentials_005fget"><code>gnutls_credentials_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcredentials_005fset"><code>gnutls_credentials_set</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Session-initialization">Session initialization</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcredentials_005fset-1"><code>gnutls_credentials_set</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcrypto_005fregister_005faead_005fcipher"><code>gnutls_crypto_register_aead_cipher</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Overriding-algorithms">Overriding algorithms</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcrypto_005fregister_005faead_005fcipher-1"><code>gnutls_crypto_register_aead_cipher</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcrypto_005fregister_005fcipher"><code>gnutls_crypto_register_cipher</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Overriding-algorithms">Overriding algorithms</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcrypto_005fregister_005fcipher-1"><code>gnutls_crypto_register_cipher</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcrypto_005fregister_005fdigest"><code>gnutls_crypto_register_digest</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Overriding-algorithms">Overriding algorithms</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcrypto_005fregister_005fdigest-1"><code>gnutls_crypto_register_digest</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcrypto_005fregister_005fmac"><code>gnutls_crypto_register_mac</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Overriding-algorithms">Overriding algorithms</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fcrypto_005fregister_005fmac-1"><code>gnutls_crypto_register_mac</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdb_005fcheck_005fentry"><code>gnutls_db_check_entry</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdb_005fcheck_005fentry_005ftime"><code>gnutls_db_check_entry_time</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdb_005fget_005fdefault_005fcache_005fexpiration"><code>gnutls_db_get_default_cache_expiration</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdb_005fget_005fptr"><code>gnutls_db_get_ptr</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdb_005fremove_005fsession"><code>gnutls_db_remove_session</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdb_005fset_005fcache_005fexpiration"><code>gnutls_db_set_cache_expiration</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdb_005fset_005fptr"><code>gnutls_db_set_ptr</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdb_005fset_005fremove_005ffunction"><code>gnutls_db_set_remove_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdb_005fset_005fretrieve_005ffunction"><code>gnutls_db_set_retrieve_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdb_005fset_005fstore_005ffunction"><code>gnutls_db_set_store_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdeinit"><code>gnutls_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Data-transfer-and-termination">Data transfer and termination</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdeinit-1"><code>gnutls_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fget_005fgroup"><code>gnutls_dh_get_group</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fget_005fpeers_005fpublic_005fbits"><code>gnutls_dh_get_peers_public_bits</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fget_005fprime_005fbits"><code>gnutls_dh_get_prime_bits</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fget_005fpubkey"><code>gnutls_dh_get_pubkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fget_005fsecret_005fbits"><code>gnutls_dh_get_secret_bits</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fparams_005fcpy"><code>gnutls_dh_params_cpy</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fparams_005fdeinit"><code>gnutls_dh_params_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fparams_005fexport2_005fpkcs3"><code>gnutls_dh_params_export2_pkcs3</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fparams_005fexport_005fpkcs3"><code>gnutls_dh_params_export_pkcs3</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fparams_005fexport_005fraw"><code>gnutls_dh_params_export_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fparams_005fgenerate2"><code>gnutls_dh_params_generate2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fparams_005fimport_005fpkcs3"><code>gnutls_dh_params_import_pkcs3</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fparams_005fimport_005fraw"><code>gnutls_dh_params_import_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fparams_005fimport_005fraw2"><code>gnutls_dh_params_import_raw2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fparams_005finit"><code>gnutls_dh_params_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdh_005fset_005fprime_005fbits"><code>gnutls_dh_set_prime_bits</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdigest_005fget_005fid"><code>gnutls_digest_get_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdigest_005fget_005fname"><code>gnutls_digest_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdigest_005fget_005foid"><code>gnutls_digest_get_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdigest_005flist"><code>gnutls_digest_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdtls_005fcookie_005fsend"><code>gnutls_dtls_cookie_send</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Datagram-TLS-API">Datagram TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdtls_005fcookie_005fverify"><code>gnutls_dtls_cookie_verify</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Datagram-TLS-API">Datagram TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdtls_005fget_005fdata_005fmtu"><code>gnutls_dtls_get_data_mtu</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Datagram-TLS-API">Datagram TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdtls_005fget_005fmtu"><code>gnutls_dtls_get_mtu</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Datagram-TLS-API">Datagram TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdtls_005fget_005ftimeout"><code>gnutls_dtls_get_timeout</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Setting-up-the-transport-layer">Setting up the transport layer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdtls_005fget_005ftimeout-1"><code>gnutls_dtls_get_timeout</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Datagram-TLS-API">Datagram TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdtls_005fprestate_005fset"><code>gnutls_dtls_prestate_set</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Datagram-TLS-API">Datagram TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdtls_005fset_005fdata_005fmtu"><code>gnutls_dtls_set_data_mtu</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Datagram-TLS-API">Datagram TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdtls_005fset_005fmtu"><code>gnutls_dtls_set_mtu</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Datagram-TLS-API">Datagram TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fdtls_005fset_005ftimeouts"><code>gnutls_dtls_set_timeouts</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Datagram-TLS-API">Datagram TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fecc_005fcurve_005fget"><code>gnutls_ecc_curve_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fecc_005fcurve_005fget_005fid"><code>gnutls_ecc_curve_get_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fecc_005fcurve_005fget_005fname"><code>gnutls_ecc_curve_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fecc_005fcurve_005fget_005foid"><code>gnutls_ecc_curve_get_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fecc_005fcurve_005fget_005fsize"><code>gnutls_ecc_curve_get_size</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fecc_005fcurve_005flist"><code>gnutls_ecc_curve_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ferror_005fis_005ffatal"><code>gnutls_error_is_fatal</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Data-transfer-and-termination">Data transfer and termination</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ferror_005fis_005ffatal-1"><code>gnutls_error_is_fatal</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ferror_005fto_005falert"><code>gnutls_error_to_alert</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Handling-alerts">Handling alerts</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ferror_005fto_005falert-1"><code>gnutls_error_to_alert</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fest_005frecord_005foverhead_005fsize"><code>gnutls_est_record_overhead_size</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fext_005fget_005fdata"><code>gnutls_ext_get_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fext_005fregister"><code>gnutls_ext_register</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fext_005fset_005fdata"><code>gnutls_ext_set_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ffingerprint"><code>gnutls_fingerprint</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ffips140_005fmode_005fenabled"><code>gnutls_fips140_mode_enabled</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fglobal_005fdeinit"><code>gnutls_global_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fglobal_005finit"><code>gnutls_global_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fglobal_005fset_005faudit_005flog_005ffunction"><code>gnutls_global_set_audit_log_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Debugging-and-auditing">Debugging and auditing</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fglobal_005fset_005faudit_005flog_005ffunction-1"><code>gnutls_global_set_audit_log_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fglobal_005fset_005flog_005ffunction"><code>gnutls_global_set_log_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fglobal_005fset_005flog_005flevel"><code>gnutls_global_set_log_level</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fglobal_005fset_005fmem_005ffunctions"><code>gnutls_global_set_mem_functions</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Compatibility-API">Compatibility API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fglobal_005fset_005fmutex"><code>gnutls_global_set_mutex</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Thread-safety">Thread safety</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fglobal_005fset_005fmutex-1"><code>gnutls_global_set_mutex</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fglobal_005fset_005ftime_005ffunction"><code>gnutls_global_set_time_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhandshake"><code>gnutls_handshake</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#TLS-handshake">TLS handshake</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhandshake-1"><code>gnutls_handshake</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhandshake_005fdescription_005fget_005fname"><code>gnutls_handshake_description_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhandshake_005fget_005flast_005fin"><code>gnutls_handshake_get_last_in</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhandshake_005fget_005flast_005fout"><code>gnutls_handshake_get_last_out</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhandshake_005fset_005fhook_005ffunction"><code>gnutls_handshake_set_hook_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhandshake_005fset_005fmax_005fpacket_005flength"><code>gnutls_handshake_set_max_packet_length</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhandshake_005fset_005fpost_005fclient_005fhello_005ffunction"><code>gnutls_handshake_set_post_client_hello_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhandshake_005fset_005fprivate_005fextensions"><code>gnutls_handshake_set_private_extensions</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhandshake_005fset_005frandom"><code>gnutls_handshake_set_random</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhandshake_005fset_005ftimeout"><code>gnutls_handshake_set_timeout</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#TLS-handshake">TLS handshake</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhandshake_005fset_005ftimeout-1"><code>gnutls_handshake_set_timeout</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhash"><code>gnutls_hash</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhash_005fdeinit"><code>gnutls_hash_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhash_005ffast"><code>gnutls_hash_fast</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhash_005fget_005flen"><code>gnutls_hash_get_len</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhash_005finit"><code>gnutls_hash_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhash_005foutput"><code>gnutls_hash_output</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fheartbeat_005fallowed"><code>gnutls_heartbeat_allowed</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fheartbeat_005fenable"><code>gnutls_heartbeat_enable</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fheartbeat_005fget_005ftimeout"><code>gnutls_heartbeat_get_timeout</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fheartbeat_005fping"><code>gnutls_heartbeat_ping</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fheartbeat_005fpong"><code>gnutls_heartbeat_pong</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fheartbeat_005fset_005ftimeouts"><code>gnutls_heartbeat_set_timeouts</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhex2bin"><code>gnutls_hex2bin</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhex_005fdecode"><code>gnutls_hex_decode</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhex_005fdecode2"><code>gnutls_hex_decode2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhex_005fencode"><code>gnutls_hex_encode</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhex_005fencode2"><code>gnutls_hex_encode2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhmac"><code>gnutls_hmac</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhmac_005fdeinit"><code>gnutls_hmac_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhmac_005ffast"><code>gnutls_hmac_fast</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhmac_005fget_005flen"><code>gnutls_hmac_get_len</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhmac_005finit"><code>gnutls_hmac_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhmac_005foutput"><code>gnutls_hmac_output</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fhmac_005fset_005fnonce"><code>gnutls_hmac_set_nonce</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005finit"><code>gnutls_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Session-initialization">Session initialization</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005finit-1"><code>gnutls_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fkey_005fgenerate"><code>gnutls_key_generate</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fkx_005fget"><code>gnutls_kx_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fkx_005fget_005fid"><code>gnutls_kx_get_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fkx_005fget_005fname"><code>gnutls_kx_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fkx_005flist"><code>gnutls_kx_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fload_005ffile"><code>gnutls_load_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fmac_005fget"><code>gnutls_mac_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fmac_005fget_005fid"><code>gnutls_mac_get_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fmac_005fget_005fkey_005fsize"><code>gnutls_mac_get_key_size</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fmac_005fget_005fname"><code>gnutls_mac_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fmac_005fget_005fnonce_005fsize"><code>gnutls_mac_get_nonce_size</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fmac_005flist"><code>gnutls_mac_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fmemcmp"><code>gnutls_memcmp</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fmemset"><code>gnutls_memset</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005fadd_005fcert"><code>gnutls_ocsp_req_add_cert</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005fadd_005fcert_005fid"><code>gnutls_ocsp_req_add_cert_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005fdeinit"><code>gnutls_ocsp_req_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005fexport"><code>gnutls_ocsp_req_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005fget_005fcert_005fid"><code>gnutls_ocsp_req_get_cert_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005fget_005fextension"><code>gnutls_ocsp_req_get_extension</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005fget_005fnonce"><code>gnutls_ocsp_req_get_nonce</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005fget_005fversion"><code>gnutls_ocsp_req_get_version</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005fimport"><code>gnutls_ocsp_req_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005finit"><code>gnutls_ocsp_req_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005fprint"><code>gnutls_ocsp_req_print</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005frandomize_005fnonce"><code>gnutls_ocsp_req_randomize_nonce</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005fset_005fextension"><code>gnutls_ocsp_req_set_extension</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005freq_005fset_005fnonce"><code>gnutls_ocsp_req_set_nonce</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fcheck_005fcrt"><code>gnutls_ocsp_resp_check_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fdeinit"><code>gnutls_ocsp_resp_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fexport"><code>gnutls_ocsp_resp_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fcerts"><code>gnutls_ocsp_resp_get_certs</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fextension"><code>gnutls_ocsp_resp_get_extension</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fnonce"><code>gnutls_ocsp_resp_get_nonce</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fproduced"><code>gnutls_ocsp_resp_get_produced</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fresponder"><code>gnutls_ocsp_resp_get_responder</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fresponder_005fraw_005fid"><code>gnutls_ocsp_resp_get_responder_raw_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fresponse"><code>gnutls_ocsp_resp_get_response</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fsignature"><code>gnutls_ocsp_resp_get_signature</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fsignature_005falgorithm"><code>gnutls_ocsp_resp_get_signature_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fsingle"><code>gnutls_ocsp_resp_get_single</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-certificate-status-checking">OCSP certificate status checking</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fsingle-1"><code>gnutls_ocsp_resp_get_single</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fstatus"><code>gnutls_ocsp_resp_get_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fget_005fversion"><code>gnutls_ocsp_resp_get_version</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fimport"><code>gnutls_ocsp_resp_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005finit"><code>gnutls_ocsp_resp_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fprint"><code>gnutls_ocsp_resp_print</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fverify"><code>gnutls_ocsp_resp_verify</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fresp_005fverify_005fdirect"><code>gnutls_ocsp_resp_verify_direct</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fstatus_005frequest_005fenable_005fclient"><code>gnutls_ocsp_status_request_enable_client</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fstatus_005frequest_005fget"><code>gnutls_ocsp_status_request_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005focsp_005fstatus_005frequest_005fis_005fchecked"><code>gnutls_ocsp_status_request_is_checked</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005foid_005fto_005fdigest"><code>gnutls_oid_to_digest</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005foid_005fto_005fecc_005fcurve"><code>gnutls_oid_to_ecc_curve</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005foid_005fto_005fpk"><code>gnutls_oid_to_pk</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005foid_005fto_005fsign"><code>gnutls_oid_to_sign</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fcheck_005femail"><code>gnutls_openpgp_crt_check_email</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fcheck_005fhostname"><code>gnutls_openpgp_crt_check_hostname</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fcheck_005fhostname2"><code>gnutls_openpgp_crt_check_hostname2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fdeinit"><code>gnutls_openpgp_crt_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fexport"><code>gnutls_openpgp_crt_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fexport2"><code>gnutls_openpgp_crt_export2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fauth_005fsubkey"><code>gnutls_openpgp_crt_get_auth_subkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fcreation_005ftime"><code>gnutls_openpgp_crt_get_creation_time</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fexpiration_005ftime"><code>gnutls_openpgp_crt_get_expiration_time</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005ffingerprint"><code>gnutls_openpgp_crt_get_fingerprint</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fkey_005fid"><code>gnutls_openpgp_crt_get_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fkey_005fusage"><code>gnutls_openpgp_crt_get_key_usage</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fname"><code>gnutls_openpgp_crt_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fpk_005falgorithm"><code>gnutls_openpgp_crt_get_pk_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fpk_005fdsa_005fraw"><code>gnutls_openpgp_crt_get_pk_dsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fpk_005frsa_005fraw"><code>gnutls_openpgp_crt_get_pk_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fpreferred_005fkey_005fid"><code>gnutls_openpgp_crt_get_preferred_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005frevoked_005fstatus"><code>gnutls_openpgp_crt_get_revoked_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fcount"><code>gnutls_openpgp_crt_get_subkey_count</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fcreation_005ftime"><code>gnutls_openpgp_crt_get_subkey_creation_time</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fexpiration_005ftime"><code>gnutls_openpgp_crt_get_subkey_expiration_time</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005ffingerprint"><code>gnutls_openpgp_crt_get_subkey_fingerprint</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fid"><code>gnutls_openpgp_crt_get_subkey_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fidx"><code>gnutls_openpgp_crt_get_subkey_idx</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fpk_005falgorithm"><code>gnutls_openpgp_crt_get_subkey_pk_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fpk_005fdsa_005fraw"><code>gnutls_openpgp_crt_get_subkey_pk_dsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fpk_005frsa_005fraw"><code>gnutls_openpgp_crt_get_subkey_pk_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005frevoked_005fstatus"><code>gnutls_openpgp_crt_get_subkey_revoked_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fsubkey_005fusage"><code>gnutls_openpgp_crt_get_subkey_usage</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fget_005fversion"><code>gnutls_openpgp_crt_get_version</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fimport"><code>gnutls_openpgp_crt_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005finit"><code>gnutls_openpgp_crt_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fprint"><code>gnutls_openpgp_crt_print</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fset_005fpreferred_005fkey_005fid"><code>gnutls_openpgp_crt_set_preferred_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fverify_005fring"><code>gnutls_openpgp_crt_verify_ring</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-certificates">OpenPGP certificates</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fverify_005fring-1"><code>gnutls_openpgp_crt_verify_ring</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fverify_005fself"><code>gnutls_openpgp_crt_verify_self</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-certificates">OpenPGP certificates</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fcrt_005fverify_005fself-1"><code>gnutls_openpgp_crt_verify_self</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fkeyring_005fcheck_005fid"><code>gnutls_openpgp_keyring_check_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fkeyring_005fdeinit"><code>gnutls_openpgp_keyring_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fkeyring_005fget_005fcrt"><code>gnutls_openpgp_keyring_get_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fkeyring_005fget_005fcrt_005fcount"><code>gnutls_openpgp_keyring_get_crt_count</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fkeyring_005fimport"><code>gnutls_openpgp_keyring_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fkeyring_005finit"><code>gnutls_openpgp_keyring_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fdeinit"><code>gnutls_openpgp_privkey_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fexport"><code>gnutls_openpgp_privkey_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fexport2"><code>gnutls_openpgp_privkey_export2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fexport_005fdsa_005fraw"><code>gnutls_openpgp_privkey_export_dsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fexport_005frsa_005fraw"><code>gnutls_openpgp_privkey_export_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fexport_005fsubkey_005fdsa_005fraw"><code>gnutls_openpgp_privkey_export_subkey_dsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fexport_005fsubkey_005frsa_005fraw"><code>gnutls_openpgp_privkey_export_subkey_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005ffingerprint"><code>gnutls_openpgp_privkey_get_fingerprint</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005fkey_005fid"><code>gnutls_openpgp_privkey_get_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005fpk_005falgorithm"><code>gnutls_openpgp_privkey_get_pk_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005fpreferred_005fkey_005fid"><code>gnutls_openpgp_privkey_get_preferred_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005frevoked_005fstatus"><code>gnutls_openpgp_privkey_get_revoked_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fcount"><code>gnutls_openpgp_privkey_get_subkey_count</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fcreation_005ftime"><code>gnutls_openpgp_privkey_get_subkey_creation_time</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fexpiration_005ftime"><code>gnutls_openpgp_privkey_get_subkey_expiration_time</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005ffingerprint"><code>gnutls_openpgp_privkey_get_subkey_fingerprint</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fid"><code>gnutls_openpgp_privkey_get_subkey_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fidx"><code>gnutls_openpgp_privkey_get_subkey_idx</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005fpk_005falgorithm"><code>gnutls_openpgp_privkey_get_subkey_pk_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fget_005fsubkey_005frevoked_005fstatus"><code>gnutls_openpgp_privkey_get_subkey_revoked_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fimport"><code>gnutls_openpgp_privkey_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005finit"><code>gnutls_openpgp_privkey_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fsec_005fparam"><code>gnutls_openpgp_privkey_sec_param</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fset_005fpreferred_005fkey_005fid"><code>gnutls_openpgp_privkey_set_preferred_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fprivkey_005fsign_005fhash"><code>gnutls_openpgp_privkey_sign_hash</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Compatibility-API">Compatibility API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fsend_005fcert"><code>gnutls_openpgp_send_cert</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fopenpgp_005fset_005frecv_005fkey_005ffunction"><code>gnutls_openpgp_set_recv_key_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpacket_005fdeinit"><code>gnutls_packet_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpacket_005fget"><code>gnutls_packet_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpcert_005fdeinit"><code>gnutls_pcert_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpcert_005fexport_005fopenpgp"><code>gnutls_pcert_export_openpgp</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpcert_005fexport_005fx509"><code>gnutls_pcert_export_x509</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpcert_005fimport_005fopenpgp"><code>gnutls_pcert_import_openpgp</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpcert_005fimport_005fopenpgp_005fraw"><code>gnutls_pcert_import_openpgp_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpcert_005fimport_005fx509"><code>gnutls_pcert_import_x509</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpcert_005fimport_005fx509_005flist"><code>gnutls_pcert_import_x509_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpcert_005fimport_005fx509_005fraw"><code>gnutls_pcert_import_x509_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpcert_005flist_005fimport_005fx509_005fraw"><code>gnutls_pcert_list_import_x509_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpem_005fbase64_005fdecode"><code>gnutls_pem_base64_decode</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpem_005fbase64_005fdecode2"><code>gnutls_pem_base64_decode2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpem_005fbase64_005fencode"><code>gnutls_pem_base64_encode</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpem_005fbase64_005fencode2"><code>gnutls_pem_base64_encode2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fperror"><code>gnutls_perror</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fadd_005fprovider"><code>gnutls_pkcs11_add_provider</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fcopy_005fattached_005fextension"><code>gnutls_pkcs11_copy_attached_extension</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fcopy_005fpubkey"><code>gnutls_pkcs11_copy_pubkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fcopy_005fsecret_005fkey"><code>gnutls_pkcs11_copy_secret_key</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fcopy_005fx509_005fcrt"><code>gnutls_pkcs11_copy_x509_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fcopy_005fx509_005fcrt2"><code>gnutls_pkcs11_copy_x509_crt2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Writing-objects">Writing objects</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fcopy_005fx509_005fcrt2-1"><code>gnutls_pkcs11_copy_x509_crt2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fcopy_005fx509_005fprivkey"><code>gnutls_pkcs11_copy_x509_privkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fcopy_005fx509_005fprivkey2"><code>gnutls_pkcs11_copy_x509_privkey2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Writing-objects">Writing objects</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fcopy_005fx509_005fprivkey2-1"><code>gnutls_pkcs11_copy_x509_privkey2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fcrt_005fis_005fknown"><code>gnutls_pkcs11_crt_is_known</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fdeinit"><code>gnutls_pkcs11_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fdelete_005furl"><code>gnutls_pkcs11_delete_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Writing-objects">Writing objects</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fdelete_005furl-1"><code>gnutls_pkcs11_delete_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fget_005fpin_005ffunction"><code>gnutls_pkcs11_get_pin_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fget_005fraw_005fissuer"><code>gnutls_pkcs11_get_raw_issuer</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fget_005fraw_005fissuer_005fby_005fdn"><code>gnutls_pkcs11_get_raw_issuer_by_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fget_005fraw_005fissuer_005fby_005fsubject_005fkey_005fid"><code>gnutls_pkcs11_get_raw_issuer_by_subject_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005finit"><code>gnutls_pkcs11_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS11-Initialization">PKCS11 Initialization</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005finit-1"><code>gnutls_pkcs11_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fdeinit"><code>gnutls_pkcs11_obj_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fexport"><code>gnutls_pkcs11_obj_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fexport2"><code>gnutls_pkcs11_obj_export2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fexport3"><code>gnutls_pkcs11_obj_export3</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fexport_005furl"><code>gnutls_pkcs11_obj_export_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fflags_005fget_005fstr"><code>gnutls_pkcs11_obj_flags_get_str</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fget_005fexts"><code>gnutls_pkcs11_obj_get_exts</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fget_005fflags"><code>gnutls_pkcs11_obj_get_flags</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fget_005finfo"><code>gnutls_pkcs11_obj_get_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Reading-objects">Reading objects</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fget_005finfo-1"><code>gnutls_pkcs11_obj_get_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fget_005ftype"><code>gnutls_pkcs11_obj_get_type</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fimport_005furl"><code>gnutls_pkcs11_obj_import_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005finit"><code>gnutls_pkcs11_obj_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005flist_005fimport_005furl3"><code>gnutls_pkcs11_obj_list_import_url3</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005flist_005fimport_005furl4"><code>gnutls_pkcs11_obj_list_import_url4</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fset_005finfo"><code>gnutls_pkcs11_obj_set_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fobj_005fset_005fpin_005ffunction"><code>gnutls_pkcs11_obj_set_pin_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005fcpy"><code>gnutls_pkcs11_privkey_cpy</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005fdeinit"><code>gnutls_pkcs11_privkey_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005fexport_005fpubkey"><code>gnutls_pkcs11_privkey_export_pubkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005fexport_005furl"><code>gnutls_pkcs11_privkey_export_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005fgenerate"><code>gnutls_pkcs11_privkey_generate</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005fgenerate2"><code>gnutls_pkcs11_privkey_generate2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005fgenerate3"><code>gnutls_pkcs11_privkey_generate3</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005fget_005finfo"><code>gnutls_pkcs11_privkey_get_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005fget_005fpk_005falgorithm"><code>gnutls_pkcs11_privkey_get_pk_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005fimport_005furl"><code>gnutls_pkcs11_privkey_import_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005finit"><code>gnutls_pkcs11_privkey_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005fset_005fpin_005ffunction"><code>gnutls_pkcs11_privkey_set_pin_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fprivkey_005fstatus"><code>gnutls_pkcs11_privkey_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005freinit"><code>gnutls_pkcs11_reinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fset_005fpin_005ffunction"><code>gnutls_pkcs11_set_pin_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005fset_005ftoken_005ffunction"><code>gnutls_pkcs11_set_token_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005ftoken_005fget_005fflags"><code>gnutls_pkcs11_token_get_flags</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005ftoken_005fget_005finfo"><code>gnutls_pkcs11_token_get_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005ftoken_005fget_005fmechanism"><code>gnutls_pkcs11_token_get_mechanism</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005ftoken_005fget_005frandom"><code>gnutls_pkcs11_token_get_random</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005ftoken_005fget_005furl"><code>gnutls_pkcs11_token_get_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005ftoken_005finit"><code>gnutls_pkcs11_token_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005ftoken_005fset_005fpin"><code>gnutls_pkcs11_token_set_pin</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs11_005ftype_005fget_005fname"><code>gnutls_pkcs11_type_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fdecrypt"><code>gnutls_pkcs12_bag_decrypt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fdeinit"><code>gnutls_pkcs12_bag_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fencrypt"><code>gnutls_pkcs12_bag_encrypt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fenc_005finfo"><code>gnutls_pkcs12_bag_enc_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fget_005fcount"><code>gnutls_pkcs12_bag_get_count</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fget_005fdata"><code>gnutls_pkcs12_bag_get_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fget_005ffriendly_005fname"><code>gnutls_pkcs12_bag_get_friendly_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fget_005fkey_005fid"><code>gnutls_pkcs12_bag_get_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fget_005ftype"><code>gnutls_pkcs12_bag_get_type</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005finit"><code>gnutls_pkcs12_bag_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fset_005fcrl"><code>gnutls_pkcs12_bag_set_crl</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fset_005fcrt"><code>gnutls_pkcs12_bag_set_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fset_005fdata"><code>gnutls_pkcs12_bag_set_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fset_005ffriendly_005fname"><code>gnutls_pkcs12_bag_set_friendly_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fset_005fkey_005fid"><code>gnutls_pkcs12_bag_set_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fbag_005fset_005fprivkey"><code>gnutls_pkcs12_bag_set_privkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fdeinit"><code>gnutls_pkcs12_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fexport"><code>gnutls_pkcs12_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fexport2"><code>gnutls_pkcs12_export2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fgenerate_005fmac"><code>gnutls_pkcs12_generate_mac</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fgenerate_005fmac2"><code>gnutls_pkcs12_generate_mac2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fget_005fbag"><code>gnutls_pkcs12_get_bag</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fimport"><code>gnutls_pkcs12_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005finit"><code>gnutls_pkcs12_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fmac_005finfo"><code>gnutls_pkcs12_mac_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fset_005fbag"><code>gnutls_pkcs12_set_bag</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fsimple_005fparse"><code>gnutls_pkcs12_simple_parse</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Managing-encrypted-keys">Managing encrypted keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fsimple_005fparse-1"><code>gnutls_pkcs12_simple_parse</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs12_005fverify_005fmac"><code>gnutls_pkcs12_verify_mac</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-12-API">PKCS 12 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fadd_005fattr"><code>gnutls_pkcs7_add_attr</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fattrs_005fdeinit"><code>gnutls_pkcs7_attrs_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fdeinit"><code>gnutls_pkcs7_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fdelete_005fcrl"><code>gnutls_pkcs7_delete_crl</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fdelete_005fcrt"><code>gnutls_pkcs7_delete_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fexport"><code>gnutls_pkcs7_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fexport2"><code>gnutls_pkcs7_export2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fget_005fattr"><code>gnutls_pkcs7_get_attr</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fget_005fcrl_005fcount"><code>gnutls_pkcs7_get_crl_count</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fget_005fcrl_005fraw"><code>gnutls_pkcs7_get_crl_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fget_005fcrl_005fraw2"><code>gnutls_pkcs7_get_crl_raw2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fget_005fcrt_005fcount"><code>gnutls_pkcs7_get_crt_count</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fget_005fcrt_005fraw"><code>gnutls_pkcs7_get_crt_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fget_005fcrt_005fraw2"><code>gnutls_pkcs7_get_crt_raw2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fget_005fembedded_005fdata"><code>gnutls_pkcs7_get_embedded_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fget_005fsignature_005fcount"><code>gnutls_pkcs7_get_signature_count</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fget_005fsignature_005finfo"><code>gnutls_pkcs7_get_signature_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fimport"><code>gnutls_pkcs7_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005finit"><code>gnutls_pkcs7_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fprint"><code>gnutls_pkcs7_print</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fset_005fcrl"><code>gnutls_pkcs7_set_crl</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fset_005fcrl_005fraw"><code>gnutls_pkcs7_set_crl_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fset_005fcrt"><code>gnutls_pkcs7_set_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fset_005fcrt_005fraw"><code>gnutls_pkcs7_set_crt_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fsign"><code>gnutls_pkcs7_sign</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Public-key-algorithms">Public key algorithms</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fsign-1"><code>gnutls_pkcs7_sign</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fsignature_005finfo_005fdeinit"><code>gnutls_pkcs7_signature_info_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fverify"><code>gnutls_pkcs7_verify</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs7_005fverify_005fdirect"><code>gnutls_pkcs7_verify_direct</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-7-API">PKCS 7 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs8_005finfo"><code>gnutls_pkcs8_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs_005fschema_005fget_005fname"><code>gnutls_pkcs_schema_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpkcs_005fschema_005fget_005foid"><code>gnutls_pkcs_schema_get_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpk_005falgorithm_005fget_005fname"><code>gnutls_pk_algorithm_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpk_005fbits_005fto_005fsec_005fparam"><code>gnutls_pk_bits_to_sec_param</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Selecting-cryptographic-key-sizes">Selecting cryptographic key sizes</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpk_005fbits_005fto_005fsec_005fparam-1"><code>gnutls_pk_bits_to_sec_param</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpk_005fget_005fid"><code>gnutls_pk_get_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpk_005fget_005fname"><code>gnutls_pk_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpk_005fget_005foid"><code>gnutls_pk_get_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpk_005flist"><code>gnutls_pk_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpk_005fto_005fsign"><code>gnutls_pk_to_sign</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprf"><code>gnutls_prf</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprf_005fraw"><code>gnutls_prf_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprf_005frfc5705"><code>gnutls_prf_rfc5705</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fcertificate_005ftype_005flist"><code>gnutls_priority_certificate_type_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fcipher_005flist"><code>gnutls_priority_cipher_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fcompression_005flist"><code>gnutls_priority_compression_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fdeinit"><code>gnutls_priority_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fecc_005fcurve_005flist"><code>gnutls_priority_ecc_curve_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fget_005fcipher_005fsuite_005findex"><code>gnutls_priority_get_cipher_suite_index</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005finit"><code>gnutls_priority_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fkx_005flist"><code>gnutls_priority_kx_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fmac_005flist"><code>gnutls_priority_mac_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fprotocol_005flist"><code>gnutls_priority_protocol_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fset"><code>gnutls_priority_set</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fset_005fdirect"><code>gnutls_priority_set_direct</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fsign_005flist"><code>gnutls_priority_sign_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpriority_005fstring_005flist"><code>gnutls_priority_string_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fdecrypt_005fdata"><code>gnutls_privkey_decrypt_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Operations">Operations</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fdecrypt_005fdata-1"><code>gnutls_privkey_decrypt_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fdeinit"><code>gnutls_privkey_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fexport_005fdsa_005fraw"><code>gnutls_privkey_export_dsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fexport_005fecc_005fraw"><code>gnutls_privkey_export_ecc_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fexport_005fopenpgp"><code>gnutls_privkey_export_openpgp</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fexport_005fpkcs11"><code>gnutls_privkey_export_pkcs11</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fexport_005frsa_005fraw"><code>gnutls_privkey_export_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fexport_005fx509"><code>gnutls_privkey_export_x509</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fgenerate"><code>gnutls_privkey_generate</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fget_005fpk_005falgorithm"><code>gnutls_privkey_get_pk_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fget_005ftype"><code>gnutls_privkey_get_type</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fdsa_005fraw"><code>gnutls_privkey_import_dsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fecc_005fraw"><code>gnutls_privkey_import_ecc_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fext"><code>gnutls_privkey_import_ext</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fext2"><code>gnutls_privkey_import_ext2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fext3"><code>gnutls_privkey_import_ext3</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-private-keys">Abstract private keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fext3-1"><code>gnutls_privkey_import_ext3</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fopenpgp"><code>gnutls_privkey_import_openpgp</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fopenpgp_005fraw"><code>gnutls_privkey_import_openpgp_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fpkcs11"><code>gnutls_privkey_import_pkcs11</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fpkcs11_005furl"><code>gnutls_privkey_import_pkcs11_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005frsa_005fraw"><code>gnutls_privkey_import_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005ftpm_005fraw"><code>gnutls_privkey_import_tpm_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005ftpm_005furl"><code>gnutls_privkey_import_tpm_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Using-keys">Using keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005ftpm_005furl-1"><code>gnutls_privkey_import_tpm_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005furl"><code>gnutls_privkey_import_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-private-keys">Abstract private keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005furl-1"><code>gnutls_privkey_import_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fx509"><code>gnutls_privkey_import_x509</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fx509_005fraw"><code>gnutls_privkey_import_x509_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Managing-encrypted-keys">Managing encrypted keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fimport_005fx509_005fraw-1"><code>gnutls_privkey_import_x509_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005finit"><code>gnutls_privkey_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fset_005fpin_005ffunction"><code>gnutls_privkey_set_pin_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fsign_005fdata"><code>gnutls_privkey_sign_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Operations">Operations</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fsign_005fdata-1"><code>gnutls_privkey_sign_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fsign_005fhash"><code>gnutls_privkey_sign_hash</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Operations">Operations</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fsign_005fhash-1"><code>gnutls_privkey_sign_hash</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fstatus"><code>gnutls_privkey_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprivkey_005fverify_005fparams"><code>gnutls_privkey_verify_params</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprotocol_005fget_005fid"><code>gnutls_protocol_get_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprotocol_005fget_005fname"><code>gnutls_protocol_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprotocol_005fget_005fversion"><code>gnutls_protocol_get_version</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fprotocol_005flist"><code>gnutls_protocol_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fallocate_005fclient_005fcredentials"><code>gnutls_psk_allocate_client_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fallocate_005fserver_005fcredentials"><code>gnutls_psk_allocate_server_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fclient_005fget_005fhint"><code>gnutls_psk_client_get_hint</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005ffree_005fclient_005fcredentials"><code>gnutls_psk_free_client_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005ffree_005fserver_005fcredentials"><code>gnutls_psk_free_server_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fserver_005fget_005fusername"><code>gnutls_psk_server_get_username</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fset_005fclient_005fcredentials"><code>gnutls_psk_set_client_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fset_005fclient_005fcredentials_005ffunction"><code>gnutls_psk_set_client_credentials_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PSK-credentials">PSK credentials</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fset_005fclient_005fcredentials_005ffunction-1"><code>gnutls_psk_set_client_credentials_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fset_005fparams_005ffunction"><code>gnutls_psk_set_params_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffile"><code>gnutls_psk_set_server_credentials_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PSK-credentials">PSK credentials</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffile-1"><code>gnutls_psk_set_server_credentials_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fset_005fserver_005fcredentials_005ffunction"><code>gnutls_psk_set_server_credentials_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fset_005fserver_005fcredentials_005fhint"><code>gnutls_psk_set_server_credentials_hint</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fset_005fserver_005fdh_005fparams"><code>gnutls_psk_set_server_dh_params</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpsk_005fset_005fserver_005fparams_005ffunction"><code>gnutls_psk_set_server_params_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fdeinit"><code>gnutls_pubkey_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fencrypt_005fdata"><code>gnutls_pubkey_encrypt_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Operations">Operations</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fencrypt_005fdata-1"><code>gnutls_pubkey_encrypt_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fexport"><code>gnutls_pubkey_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fexport2"><code>gnutls_pubkey_export2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-public-keys">Abstract public keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fexport2-1"><code>gnutls_pubkey_export2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fexport_005fdsa_005fraw"><code>gnutls_pubkey_export_dsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fexport_005fecc_005fraw"><code>gnutls_pubkey_export_ecc_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fexport_005fecc_005fx962"><code>gnutls_pubkey_export_ecc_x962</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fexport_005frsa_005fraw"><code>gnutls_pubkey_export_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fget_005fkey_005fid"><code>gnutls_pubkey_get_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fget_005fkey_005fusage"><code>gnutls_pubkey_get_key_usage</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fget_005fopenpgp_005fkey_005fid"><code>gnutls_pubkey_get_openpgp_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fget_005fpk_005falgorithm"><code>gnutls_pubkey_get_pk_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fget_005fpreferred_005fhash_005falgorithm"><code>gnutls_pubkey_get_preferred_hash_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport"><code>gnutls_pubkey_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005fdsa_005fraw"><code>gnutls_pubkey_import_dsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005fecc_005fraw"><code>gnutls_pubkey_import_ecc_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005fecc_005fx962"><code>gnutls_pubkey_import_ecc_x962</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005fopenpgp"><code>gnutls_pubkey_import_openpgp</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005fopenpgp_005fraw"><code>gnutls_pubkey_import_openpgp_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005fpkcs11"><code>gnutls_pubkey_import_pkcs11</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005fprivkey"><code>gnutls_pubkey_import_privkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005frsa_005fraw"><code>gnutls_pubkey_import_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005ftpm_005fraw"><code>gnutls_pubkey_import_tpm_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005ftpm_005furl"><code>gnutls_pubkey_import_tpm_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Using-keys">Using keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005ftpm_005furl-1"><code>gnutls_pubkey_import_tpm_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005furl"><code>gnutls_pubkey_import_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005fx509"><code>gnutls_pubkey_import_x509</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005fx509_005fcrq"><code>gnutls_pubkey_import_x509_crq</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fimport_005fx509_005fraw"><code>gnutls_pubkey_import_x509_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005finit"><code>gnutls_pubkey_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fprint"><code>gnutls_pubkey_print</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fset_005fkey_005fusage"><code>gnutls_pubkey_set_key_usage</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fset_005fpin_005ffunction"><code>gnutls_pubkey_set_pin_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fverify_005fdata2"><code>gnutls_pubkey_verify_data2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Operations">Operations</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fverify_005fdata2-1"><code>gnutls_pubkey_verify_data2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fverify_005fhash2"><code>gnutls_pubkey_verify_hash2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Operations">Operations</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fverify_005fhash2-1"><code>gnutls_pubkey_verify_hash2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fpubkey_005fverify_005fparams"><code>gnutls_pubkey_verify_params</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frandom_005fart"><code>gnutls_random_art</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frange_005fsplit"><code>gnutls_range_split</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fcan_005fuse_005flength_005fhiding"><code>gnutls_record_can_use_length_hiding</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fcheck_005fcorked"><code>gnutls_record_check_corked</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fcheck_005fpending"><code>gnutls_record_check_pending</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Data-transfer-and-termination">Data transfer and termination</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fcheck_005fpending-1"><code>gnutls_record_check_pending</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fcork"><code>gnutls_record_cork</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Buffered-data-transfer">Buffered data transfer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fcork-1"><code>gnutls_record_cork</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fdisable_005fpadding"><code>gnutls_record_disable_padding</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fdiscard_005fqueued"><code>gnutls_record_discard_queued</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fget_005fdirection"><code>gnutls_record_get_direction</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Asynchronous-operation">Asynchronous operation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fget_005fdirection-1"><code>gnutls_record_get_direction</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fget_005fdiscarded"><code>gnutls_record_get_discarded</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Datagram-TLS-API">Datagram TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fget_005fmax_005fsize"><code>gnutls_record_get_max_size</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fget_005fstate"><code>gnutls_record_get_state</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005foverhead_005fsize"><code>gnutls_record_overhead_size</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005frecv"><code>gnutls_record_recv</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Data-transfer-and-termination">Data transfer and termination</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005frecv-1"><code>gnutls_record_recv</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005frecv_005fpacket"><code>gnutls_record_recv_packet</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005frecv_005fseq"><code>gnutls_record_recv_seq</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Data-transfer-and-termination">Data transfer and termination</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005frecv_005fseq-1"><code>gnutls_record_recv_seq</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fsend"><code>gnutls_record_send</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Data-transfer-and-termination">Data transfer and termination</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fsend-1"><code>gnutls_record_send</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fsend_005frange"><code>gnutls_record_send_range</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fset_005fmax_005fsize"><code>gnutls_record_set_max_size</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fset_005fstate"><code>gnutls_record_set_state</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005fset_005ftimeout"><code>gnutls_record_set_timeout</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005funcork"><code>gnutls_record_uncork</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Buffered-data-transfer">Buffered data transfer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frecord_005funcork-1"><code>gnutls_record_uncork</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fregister_005fcustom_005furl"><code>gnutls_register_custom_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Application_002dspecific-keys">Application-specific keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fregister_005fcustom_005furl-1"><code>gnutls_register_custom_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frehandshake"><code>gnutls_rehandshake</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Re_002dauthentication">Re-authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frehandshake-1"><code>gnutls_rehandshake</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frnd"><code>gnutls_rnd</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Random-number-generation">Random number generation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frnd-1"><code>gnutls_rnd</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005frnd_005frefresh"><code>gnutls_rnd_refresh</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Cryptographic-API">Cryptographic API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsafe_005frenegotiation_005fstatus"><code>gnutls_safe_renegotiation_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Re_002dauthentication">Re-authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsafe_005frenegotiation_005fstatus-1"><code>gnutls_safe_renegotiation_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsec_005fparam_005fget_005fname"><code>gnutls_sec_param_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsec_005fparam_005fto_005fpk_005fbits"><code>gnutls_sec_param_to_pk_bits</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Selecting-cryptographic-key-sizes">Selecting cryptographic key sizes</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsec_005fparam_005fto_005fpk_005fbits-1"><code>gnutls_sec_param_to_pk_bits</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsec_005fparam_005fto_005fsymmetric_005fbits"><code>gnutls_sec_param_to_symmetric_bits</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fserver_005fname_005fget"><code>gnutls_server_name_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fserver_005fname_005fset"><code>gnutls_server_name_set</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fchannel_005fbinding"><code>gnutls_session_channel_binding</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fenable_005fcompatibility_005fmode"><code>gnutls_session_enable_compatibility_mode</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fetm_005fstatus"><code>gnutls_session_etm_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fext_005fmaster_005fsecret_005fstatus"><code>gnutls_session_ext_master_secret_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fforce_005fvalid"><code>gnutls_session_force_valid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fget_005fdata"><code>gnutls_session_get_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fget_005fdata2"><code>gnutls_session_get_data2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fget_005fdesc"><code>gnutls_session_get_desc</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fget_005fid"><code>gnutls_session_get_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fget_005fid2"><code>gnutls_session_get_id2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fget_005fptr"><code>gnutls_session_get_ptr</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fget_005frandom"><code>gnutls_session_get_random</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fget_005fverify_005fcert_005fstatus"><code>gnutls_session_get_verify_cert_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fis_005fresumed"><code>gnutls_session_is_resumed</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Session-resumption">Session resumption</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fis_005fresumed-1"><code>gnutls_session_is_resumed</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fresumption_005frequested"><code>gnutls_session_resumption_requested</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Session-resumption">Session resumption</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fresumption_005frequested-1"><code>gnutls_session_resumption_requested</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fset_005fdata"><code>gnutls_session_set_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fset_005fid"><code>gnutls_session_set_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fset_005fpremaster"><code>gnutls_session_set_premaster</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fset_005fptr"><code>gnutls_session_set_ptr</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fset_005fverify_005fcert"><code>gnutls_session_set_verify_cert</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-credentials">Certificate credentials</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fset_005fverify_005fcert-1"><code>gnutls_session_set_verify_cert</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fset_005fverify_005fcert2"><code>gnutls_session_set_verify_cert2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fset_005fverify_005ffunction"><code>gnutls_session_set_verify_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fticket_005fenable_005fclient"><code>gnutls_session_ticket_enable_client</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fticket_005fenable_005fserver"><code>gnutls_session_ticket_enable_server</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Session-resumption">Session resumption</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fticket_005fenable_005fserver-1"><code>gnutls_session_ticket_enable_server</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fticket_005fkey_005fgenerate"><code>gnutls_session_ticket_key_generate</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Session-resumption">Session resumption</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsession_005fticket_005fkey_005fgenerate-1"><code>gnutls_session_ticket_key_generate</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fset_005fdefault_005fpriority"><code>gnutls_set_default_priority</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsign_005falgorithm_005fget"><code>gnutls_sign_algorithm_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsign_005falgorithm_005fget_005fclient"><code>gnutls_sign_algorithm_get_client</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsign_005falgorithm_005fget_005frequested"><code>gnutls_sign_algorithm_get_requested</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsign_005fget_005fhash_005falgorithm"><code>gnutls_sign_get_hash_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsign_005fget_005fid"><code>gnutls_sign_get_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsign_005fget_005fname"><code>gnutls_sign_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsign_005fget_005foid"><code>gnutls_sign_get_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsign_005fget_005fpk_005falgorithm"><code>gnutls_sign_get_pk_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsign_005fis_005fsecure"><code>gnutls_sign_is_secure</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsign_005flist"><code>gnutls_sign_list</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fallocate_005fclient_005fcredentials"><code>gnutls_srp_allocate_client_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fallocate_005fserver_005fcredentials"><code>gnutls_srp_allocate_server_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fbase64_005fdecode"><code>gnutls_srp_base64_decode</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fbase64_005fdecode2"><code>gnutls_srp_base64_decode2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fbase64_005fencode"><code>gnutls_srp_base64_encode</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fbase64_005fencode2"><code>gnutls_srp_base64_encode2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005ffree_005fclient_005fcredentials"><code>gnutls_srp_free_client_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005ffree_005fserver_005fcredentials"><code>gnutls_srp_free_server_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fserver_005fget_005fusername"><code>gnutls_srp_server_get_username</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fset_005fclient_005fcredentials"><code>gnutls_srp_set_client_credentials</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fset_005fclient_005fcredentials_005ffunction"><code>gnutls_srp_set_client_credentials_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#SRP-credentials">SRP credentials</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fset_005fclient_005fcredentials_005ffunction-1"><code>gnutls_srp_set_client_credentials_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fset_005fprime_005fbits"><code>gnutls_srp_set_prime_bits</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffile"><code>gnutls_srp_set_server_credentials_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#SRP-credentials">SRP credentials</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffile-1"><code>gnutls_srp_set_server_credentials_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffunction"><code>gnutls_srp_set_server_credentials_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#SRP-credentials">SRP credentials</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffunction-1"><code>gnutls_srp_set_server_credentials_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fset_005fserver_005ffake_005fsalt_005fseed"><code>gnutls_srp_set_server_fake_salt_seed</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fverifier"><code>gnutls_srp_verifier</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Authentication-using-SRP">Authentication using SRP</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrp_005fverifier-1"><code>gnutls_srp_verifier</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrtp_005fget_005fkeys"><code>gnutls_srtp_get_keys</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#SRTP">SRTP</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrtp_005fget_005fkeys-1"><code>gnutls_srtp_get_keys</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrtp_005fget_005fmki"><code>gnutls_srtp_get_mki</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrtp_005fget_005fprofile_005fid"><code>gnutls_srtp_get_profile_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrtp_005fget_005fprofile_005fname"><code>gnutls_srtp_get_profile_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrtp_005fget_005fselected_005fprofile"><code>gnutls_srtp_get_selected_profile</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrtp_005fset_005fmki"><code>gnutls_srtp_set_mki</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrtp_005fset_005fprofile"><code>gnutls_srtp_set_profile</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsrtp_005fset_005fprofile_005fdirect"><code>gnutls_srtp_set_profile_direct</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fstore_005fcommitment"><code>gnutls_store_commitment</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-verification">Certificate verification</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fstore_005fcommitment-1"><code>gnutls_store_commitment</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fstore_005fpubkey"><code>gnutls_store_pubkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-verification">Certificate verification</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fstore_005fpubkey-1"><code>gnutls_store_pubkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fstrerror"><code>gnutls_strerror</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fstrerror_005fname"><code>gnutls_strerror_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsubject_005falt_005fnames_005fdeinit"><code>gnutls_subject_alt_names_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsubject_005falt_005fnames_005fget"><code>gnutls_subject_alt_names_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsubject_005falt_005fnames_005finit"><code>gnutls_subject_alt_names_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsubject_005falt_005fnames_005fset"><code>gnutls_subject_alt_names_set</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsupplemental_005fget_005fname"><code>gnutls_supplemental_get_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsupplemental_005frecv"><code>gnutls_supplemental_recv</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsupplemental_005fregister"><code>gnutls_supplemental_register</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsupplemental_005fsend"><code>gnutls_supplemental_send</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsystem_005fkey_005fadd_005fx509"><code>gnutls_system_key_add_x509</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsystem_005fkey_005fdelete"><code>gnutls_system_key_delete</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsystem_005fkey_005fiter_005fdeinit"><code>gnutls_system_key_iter_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsystem_005fkey_005fiter_005fget_005finfo"><code>gnutls_system_key_iter_get_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Application_002dspecific-keys">Application-specific keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsystem_005fkey_005fiter_005fget_005finfo-1"><code>gnutls_system_key_iter_get_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fsystem_005frecv_005ftimeout"><code>gnutls_system_recv_timeout</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftdb_005fdeinit"><code>gnutls_tdb_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftdb_005finit"><code>gnutls_tdb_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftdb_005fset_005fstore_005fcommitment_005ffunc"><code>gnutls_tdb_set_store_commitment_func</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftdb_005fset_005fstore_005ffunc"><code>gnutls_tdb_set_store_func</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftdb_005fset_005fverify_005ffunc"><code>gnutls_tdb_set_verify_func</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftpm_005fget_005fregistered"><code>gnutls_tpm_get_registered</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#TPM-API">TPM API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftpm_005fkey_005flist_005fdeinit"><code>gnutls_tpm_key_list_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#TPM-API">TPM API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftpm_005fkey_005flist_005fget_005furl"><code>gnutls_tpm_key_list_get_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#TPM-API">TPM API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftpm_005fprivkey_005fdelete"><code>gnutls_tpm_privkey_delete</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Key-generation">Key generation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftpm_005fprivkey_005fdelete-1"><code>gnutls_tpm_privkey_delete</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Using-keys">Using keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftpm_005fprivkey_005fdelete-2"><code>gnutls_tpm_privkey_delete</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#TPM-API">TPM API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftpm_005fprivkey_005fgenerate"><code>gnutls_tpm_privkey_generate</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Key-generation">Key generation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftpm_005fprivkey_005fgenerate-1"><code>gnutls_tpm_privkey_generate</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#TPM-API">TPM API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fget_005fint"><code>gnutls_transport_get_int</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fget_005fint2"><code>gnutls_transport_get_int2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fget_005fptr"><code>gnutls_transport_get_ptr</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fget_005fptr2"><code>gnutls_transport_get_ptr2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005ferrno"><code>gnutls_transport_set_errno</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Setting-up-the-transport-layer">Setting up the transport layer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005ferrno-1"><code>gnutls_transport_set_errno</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005ferrno_005ffunction"><code>gnutls_transport_set_errno_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fint"><code>gnutls_transport_set_int</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fint2"><code>gnutls_transport_set_int2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fptr"><code>gnutls_transport_set_ptr</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fptr2"><code>gnutls_transport_set_ptr2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fpull_005ffunction"><code>gnutls_transport_set_pull_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Setting-up-the-transport-layer">Setting up the transport layer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fpull_005ffunction-1"><code>gnutls_transport_set_pull_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fpull_005ftimeout_005ffunction"><code>gnutls_transport_set_pull_timeout_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Setting-up-the-transport-layer">Setting up the transport layer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fpull_005ftimeout_005ffunction-1"><code>gnutls_transport_set_pull_timeout_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Setting-up-the-transport-layer">Setting up the transport layer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fpull_005ftimeout_005ffunction-2"><code>gnutls_transport_set_pull_timeout_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fpush_005ffunction"><code>gnutls_transport_set_push_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Setting-up-the-transport-layer">Setting up the transport layer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fpush_005ffunction-1"><code>gnutls_transport_set_push_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fvec_005fpush_005ffunction"><code>gnutls_transport_set_vec_push_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Setting-up-the-transport-layer">Setting up the transport layer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005ftransport_005fset_005fvec_005fpush_005ffunction-1"><code>gnutls_transport_set_vec_push_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005furl_005fis_005fsupported"><code>gnutls_url_is_supported</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-public-keys">Abstract public keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005furl_005fis_005fsupported-1"><code>gnutls_url_is_supported</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fverify_005fstored_005fpubkey"><code>gnutls_verify_stored_pubkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-verification">Certificate verification</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fverify_005fstored_005fpubkey-1"><code>gnutls_verify_stored_pubkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Core-TLS-API">Core TLS API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005faia_005fdeinit"><code>gnutls_x509_aia_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005faia_005fget"><code>gnutls_x509_aia_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005faia_005finit"><code>gnutls_x509_aia_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005faia_005fset"><code>gnutls_x509_aia_set</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005faki_005fdeinit"><code>gnutls_x509_aki_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005faki_005fget_005fcert_005fissuer"><code>gnutls_x509_aki_get_cert_issuer</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005faki_005fget_005fid"><code>gnutls_x509_aki_get_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005faki_005finit"><code>gnutls_x509_aki_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005faki_005fset_005fcert_005fissuer"><code>gnutls_x509_aki_set_cert_issuer</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005faki_005fset_005fid"><code>gnutls_x509_aki_set_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fcheck_005fissuer"><code>gnutls_x509_crl_check_issuer</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fdeinit"><code>gnutls_x509_crl_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fdist_005fpoints_005fdeinit"><code>gnutls_x509_crl_dist_points_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fdist_005fpoints_005fget"><code>gnutls_x509_crl_dist_points_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fdist_005fpoints_005finit"><code>gnutls_x509_crl_dist_points_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fdist_005fpoints_005fset"><code>gnutls_x509_crl_dist_points_set</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fexport"><code>gnutls_x509_crl_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fexport2"><code>gnutls_x509_crl_export2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fauthority_005fkey_005fgn_005fserial"><code>gnutls_x509_crl_get_authority_key_gn_serial</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fauthority_005fkey_005fid"><code>gnutls_x509_crl_get_authority_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fcrt_005fcount"><code>gnutls_x509_crl_get_crt_count</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fcrt_005fserial"><code>gnutls_x509_crl_get_crt_serial</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKIX-certificate-revocation-lists">PKIX certificate revocation lists</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fcrt_005fserial-1"><code>gnutls_x509_crl_get_crt_serial</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fdn_005foid"><code>gnutls_x509_crl_get_dn_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fextension_005fdata"><code>gnutls_x509_crl_get_extension_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fextension_005fdata2"><code>gnutls_x509_crl_get_extension_data2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fextension_005finfo"><code>gnutls_x509_crl_get_extension_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fextension_005foid"><code>gnutls_x509_crl_get_extension_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn"><code>gnutls_x509_crl_get_issuer_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn2"><code>gnutls_x509_crl_get_issuer_dn2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fissuer_005fdn_005fby_005foid"><code>gnutls_x509_crl_get_issuer_dn_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fnext_005fupdate"><code>gnutls_x509_crl_get_next_update</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fnumber"><code>gnutls_x509_crl_get_number</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fraw_005fissuer_005fdn"><code>gnutls_x509_crl_get_raw_issuer_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fsignature"><code>gnutls_x509_crl_get_signature</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fsignature_005falgorithm"><code>gnutls_x509_crl_get_signature_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fthis_005fupdate"><code>gnutls_x509_crl_get_this_update</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fget_005fversion"><code>gnutls_x509_crl_get_version</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fimport"><code>gnutls_x509_crl_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005finit"><code>gnutls_x509_crl_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fiter_005fcrt_005fserial"><code>gnutls_x509_crl_iter_crt_serial</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fiter_005fdeinit"><code>gnutls_x509_crl_iter_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005flist_005fimport"><code>gnutls_x509_crl_list_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005flist_005fimport2"><code>gnutls_x509_crl_list_import2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fprint"><code>gnutls_x509_crl_print</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fprivkey_005fsign"><code>gnutls_x509_crl_privkey_sign</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKIX-certificate-revocation-lists">PKIX certificate revocation lists</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fprivkey_005fsign-1"><code>gnutls_x509_crl_privkey_sign</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fset_005fauthority_005fkey_005fid"><code>gnutls_x509_crl_set_authority_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fset_005fcrt"><code>gnutls_x509_crl_set_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fset_005fcrt_005fserial"><code>gnutls_x509_crl_set_crt_serial</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fset_005fnext_005fupdate"><code>gnutls_x509_crl_set_next_update</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fset_005fnumber"><code>gnutls_x509_crl_set_number</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fset_005fthis_005fupdate"><code>gnutls_x509_crl_set_this_update</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fset_005fversion"><code>gnutls_x509_crl_set_version</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fsign"><code>gnutls_x509_crl_sign</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Compatibility-API">Compatibility API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fsign2"><code>gnutls_x509_crl_sign2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKIX-certificate-revocation-lists">PKIX certificate revocation lists</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fsign2-1"><code>gnutls_x509_crl_sign2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrl_005fverify"><code>gnutls_x509_crl_verify</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fdeinit"><code>gnutls_x509_crq_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fexport"><code>gnutls_x509_crq_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fexport2"><code>gnutls_x509_crq_export2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fattribute_005fby_005foid"><code>gnutls_x509_crq_get_attribute_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fattribute_005fdata"><code>gnutls_x509_crq_get_attribute_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fattribute_005finfo"><code>gnutls_x509_crq_get_attribute_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fbasic_005fconstraints"><code>gnutls_x509_crq_get_basic_constraints</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fchallenge_005fpassword"><code>gnutls_x509_crq_get_challenge_password</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fdn"><code>gnutls_x509_crq_get_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fdn2"><code>gnutls_x509_crq_get_dn2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fdn_005fby_005foid"><code>gnutls_x509_crq_get_dn_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fdn_005foid"><code>gnutls_x509_crq_get_dn_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fextension_005fby_005foid"><code>gnutls_x509_crq_get_extension_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fextension_005fby_005foid2"><code>gnutls_x509_crq_get_extension_by_oid2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fextension_005fdata"><code>gnutls_x509_crq_get_extension_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fextension_005fdata2"><code>gnutls_x509_crq_get_extension_data2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fextension_005finfo"><code>gnutls_x509_crq_get_extension_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fkey_005fid"><code>gnutls_x509_crq_get_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fkey_005fpurpose_005foid"><code>gnutls_x509_crq_get_key_purpose_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fkey_005frsa_005fraw"><code>gnutls_x509_crq_get_key_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fkey_005fusage"><code>gnutls_x509_crq_get_key_usage</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fpk_005falgorithm"><code>gnutls_x509_crq_get_pk_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fprivate_005fkey_005fusage_005fperiod"><code>gnutls_x509_crq_get_private_key_usage_period</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fsignature_005falgorithm"><code>gnutls_x509_crq_get_signature_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fsubject_005falt_005fname"><code>gnutls_x509_crq_get_subject_alt_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fsubject_005falt_005fothername_005foid"><code>gnutls_x509_crq_get_subject_alt_othername_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fget_005fversion"><code>gnutls_x509_crq_get_version</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fimport"><code>gnutls_x509_crq_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005finit"><code>gnutls_x509_crq_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fprint"><code>gnutls_x509_crq_print</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fprivkey_005fsign"><code>gnutls_x509_crq_privkey_sign</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fattribute_005fby_005foid"><code>gnutls_x509_crq_set_attribute_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fbasic_005fconstraints"><code>gnutls_x509_crq_set_basic_constraints</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fchallenge_005fpassword"><code>gnutls_x509_crq_set_challenge_password</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fdn"><code>gnutls_x509_crq_set_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fdn_005fby_005foid"><code>gnutls_x509_crq_set_dn_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fkey"><code>gnutls_x509_crq_set_key</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-10-certificate-requests">PKCS 10 certificate requests</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fkey-1"><code>gnutls_x509_crq_set_key</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fkey_005fpurpose_005foid"><code>gnutls_x509_crq_set_key_purpose_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fkey_005frsa_005fraw"><code>gnutls_x509_crq_set_key_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fkey_005fusage"><code>gnutls_x509_crq_set_key_usage</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fprivate_005fkey_005fusage_005fperiod"><code>gnutls_x509_crq_set_private_key_usage_period</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fpubkey"><code>gnutls_x509_crq_set_pubkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Operations">Operations</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fpubkey-1"><code>gnutls_x509_crq_set_pubkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fsubject_005falt_005fname"><code>gnutls_x509_crq_set_subject_alt_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fset_005fversion"><code>gnutls_x509_crq_set_version</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fsign"><code>gnutls_x509_crq_sign</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Compatibility-API">Compatibility API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fsign2"><code>gnutls_x509_crq_sign2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-10-certificate-requests">PKCS 10 certificate requests</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fsign2-1"><code>gnutls_x509_crq_sign2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrq_005fverify"><code>gnutls_x509_crq_verify</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fcheck_005femail"><code>gnutls_x509_crt_check_email</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fcheck_005fhostname"><code>gnutls_x509_crt_check_hostname</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fcheck_005fhostname2"><code>gnutls_x509_crt_check_hostname2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fcheck_005fissuer"><code>gnutls_x509_crt_check_issuer</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fcheck_005frevocation"><code>gnutls_x509_crt_check_revocation</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fcpy_005fcrl_005fdist_005fpoints"><code>gnutls_x509_crt_cpy_crl_dist_points</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fdeinit"><code>gnutls_x509_crt_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fexport"><code>gnutls_x509_crt_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fexport2"><code>gnutls_x509_crt_export2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005factivation_005ftime"><code>gnutls_x509_crt_get_activation_time</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fauthority_005finfo_005faccess"><code>gnutls_x509_crt_get_authority_info_access</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fauthority_005fkey_005fgn_005fserial"><code>gnutls_x509_crt_get_authority_key_gn_serial</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fauthority_005fkey_005fid"><code>gnutls_x509_crt_get_authority_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fbasic_005fconstraints"><code>gnutls_x509_crt_get_basic_constraints</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fca_005fstatus"><code>gnutls_x509_crt_get_ca_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fcrl_005fdist_005fpoints"><code>gnutls_x509_crt_get_crl_dist_points</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fdn"><code>gnutls_x509_crt_get_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fdn2"><code>gnutls_x509_crt_get_dn2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X_002e509-distinguished-names">X.509 distinguished names</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fdn2-1"><code>gnutls_x509_crt_get_dn2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fdn_005fby_005foid"><code>gnutls_x509_crt_get_dn_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fdn_005foid"><code>gnutls_x509_crt_get_dn_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fexpiration_005ftime"><code>gnutls_x509_crt_get_expiration_time</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fextension_005fby_005foid"><code>gnutls_x509_crt_get_extension_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fextension_005fby_005foid2"><code>gnutls_x509_crt_get_extension_by_oid2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fextension_005fdata"><code>gnutls_x509_crt_get_extension_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fextension_005fdata2"><code>gnutls_x509_crt_get_extension_data2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fextension_005finfo"><code>gnutls_x509_crt_get_extension_info</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fextension_005foid"><code>gnutls_x509_crt_get_extension_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005ffingerprint"><code>gnutls_x509_crt_get_fingerprint</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fissuer"><code>gnutls_x509_crt_get_issuer</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fissuer_005falt_005fname"><code>gnutls_x509_crt_get_issuer_alt_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fissuer_005falt_005fname2"><code>gnutls_x509_crt_get_issuer_alt_name2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fissuer_005falt_005fothername_005foid"><code>gnutls_x509_crt_get_issuer_alt_othername_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn"><code>gnutls_x509_crt_get_issuer_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn2"><code>gnutls_x509_crt_get_issuer_dn2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn_005fby_005foid"><code>gnutls_x509_crt_get_issuer_dn_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fissuer_005fdn_005foid"><code>gnutls_x509_crt_get_issuer_dn_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fissuer_005funique_005fid"><code>gnutls_x509_crt_get_issuer_unique_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fkey_005fid"><code>gnutls_x509_crt_get_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X_002e509-public-and-private-keys">X.509 public and private keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fkey_005fid-1"><code>gnutls_x509_crt_get_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fkey_005fpurpose_005foid"><code>gnutls_x509_crt_get_key_purpose_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fkey_005fusage"><code>gnutls_x509_crt_get_key_usage</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fname_005fconstraints"><code>gnutls_x509_crt_get_name_constraints</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fpk_005falgorithm"><code>gnutls_x509_crt_get_pk_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fpk_005fdsa_005fraw"><code>gnutls_x509_crt_get_pk_dsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fpk_005fecc_005fraw"><code>gnutls_x509_crt_get_pk_ecc_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fpk_005frsa_005fraw"><code>gnutls_x509_crt_get_pk_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fpolicy"><code>gnutls_x509_crt_get_policy</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fpreferred_005fhash_005falgorithm"><code>gnutls_x509_crt_get_preferred_hash_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Compatibility-API">Compatibility API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fprivate_005fkey_005fusage_005fperiod"><code>gnutls_x509_crt_get_private_key_usage_period</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fproxy"><code>gnutls_x509_crt_get_proxy</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fraw_005fdn"><code>gnutls_x509_crt_get_raw_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fraw_005fissuer_005fdn"><code>gnutls_x509_crt_get_raw_issuer_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fserial"><code>gnutls_x509_crt_get_serial</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fsignature"><code>gnutls_x509_crt_get_signature</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fsignature_005falgorithm"><code>gnutls_x509_crt_get_signature_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fsubject"><code>gnutls_x509_crt_get_subject</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fname"><code>gnutls_x509_crt_get_subject_alt_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fname2"><code>gnutls_x509_crt_get_subject_alt_name2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fsubject_005falt_005fothername_005foid"><code>gnutls_x509_crt_get_subject_alt_othername_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fsubject_005fkey_005fid"><code>gnutls_x509_crt_get_subject_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fsubject_005funique_005fid"><code>gnutls_x509_crt_get_subject_unique_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fget_005fversion"><code>gnutls_x509_crt_get_version</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fimport"><code>gnutls_x509_crt_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fimport_005fpkcs11"><code>gnutls_x509_crt_import_pkcs11</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fimport_005furl"><code>gnutls_x509_crt_import_url</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005finit"><code>gnutls_x509_crt_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005flist_005fimport"><code>gnutls_x509_crt_list_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005flist_005fimport2"><code>gnutls_x509_crt_list_import2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005flist_005fimport_005fpkcs11"><code>gnutls_x509_crt_list_import_pkcs11</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-11-API">PKCS 11 API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005flist_005fverify"><code>gnutls_x509_crt_list_verify</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fprint"><code>gnutls_x509_crt_print</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fprivkey_005fsign"><code>gnutls_x509_crt_privkey_sign</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005factivation_005ftime"><code>gnutls_x509_crt_set_activation_time</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fauthority_005finfo_005faccess"><code>gnutls_x509_crt_set_authority_info_access</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fauthority_005fkey_005fid"><code>gnutls_x509_crt_set_authority_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fbasic_005fconstraints"><code>gnutls_x509_crt_set_basic_constraints</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fca_005fstatus"><code>gnutls_x509_crt_set_ca_status</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fcrl_005fdist_005fpoints"><code>gnutls_x509_crt_set_crl_dist_points</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fcrl_005fdist_005fpoints2"><code>gnutls_x509_crt_set_crl_dist_points2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fcrq"><code>gnutls_x509_crt_set_crq</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fcrq_005fextensions"><code>gnutls_x509_crt_set_crq_extensions</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fdn"><code>gnutls_x509_crt_set_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fdn_005fby_005foid"><code>gnutls_x509_crt_set_dn_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fexpiration_005ftime"><code>gnutls_x509_crt_set_expiration_time</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fextension_005fby_005foid"><code>gnutls_x509_crt_set_extension_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fissuer_005falt_005fname"><code>gnutls_x509_crt_set_issuer_alt_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fissuer_005fdn"><code>gnutls_x509_crt_set_issuer_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fissuer_005fdn_005fby_005foid"><code>gnutls_x509_crt_set_issuer_dn_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fissuer_005funique_005fid"><code>gnutls_x509_crt_set_issuer_unique_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fkey"><code>gnutls_x509_crt_set_key</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fkey_005fpurpose_005foid"><code>gnutls_x509_crt_set_key_purpose_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fkey_005fusage"><code>gnutls_x509_crt_set_key_usage</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fname_005fconstraints"><code>gnutls_x509_crt_set_name_constraints</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fpin_005ffunction"><code>gnutls_x509_crt_set_pin_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fpolicy"><code>gnutls_x509_crt_set_policy</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fprivate_005fkey_005fusage_005fperiod"><code>gnutls_x509_crt_set_private_key_usage_period</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fproxy"><code>gnutls_x509_crt_set_proxy</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fproxy_005fdn"><code>gnutls_x509_crt_set_proxy_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fpubkey"><code>gnutls_x509_crt_set_pubkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Operations">Operations</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fpubkey-1"><code>gnutls_x509_crt_set_pubkey</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-API">Abstract key API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fserial"><code>gnutls_x509_crt_set_serial</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fsubject_005falternative_005fname"><code>gnutls_x509_crt_set_subject_alternative_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fsubject_005falt_005fname"><code>gnutls_x509_crt_set_subject_alt_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fsubject_005fkey_005fid"><code>gnutls_x509_crt_set_subject_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fsubject_005funique_005fid"><code>gnutls_x509_crt_set_subject_unique_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fset_005fversion"><code>gnutls_x509_crt_set_version</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fsign"><code>gnutls_x509_crt_sign</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fsign2"><code>gnutls_x509_crt_sign2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fverify"><code>gnutls_x509_crt_verify</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fcrt_005fverify_005fdata2"><code>gnutls_x509_crt_verify_data2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fdn_005fdeinit"><code>gnutls_x509_dn_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fdn_005fexport"><code>gnutls_x509_dn_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fdn_005fexport2"><code>gnutls_x509_dn_export2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fdn_005fget_005frdn_005fava"><code>gnutls_x509_dn_get_rdn_ava</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X_002e509-distinguished-names">X.509 distinguished names</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fdn_005fget_005frdn_005fava-1"><code>gnutls_x509_dn_get_rdn_ava</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fdn_005fget_005fstr"><code>gnutls_x509_dn_get_str</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fdn_005fimport"><code>gnutls_x509_dn_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fdn_005finit"><code>gnutls_x509_dn_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fdn_005foid_005fknown"><code>gnutls_x509_dn_oid_known</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fdn_005foid_005fname"><code>gnutls_x509_dn_oid_name</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fdeinit"><code>gnutls_x509_ext_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fexport_005faia"><code>gnutls_x509_ext_export_aia</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fexport_005fauthority_005fkey_005fid"><code>gnutls_x509_ext_export_authority_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fexport_005fbasic_005fconstraints"><code>gnutls_x509_ext_export_basic_constraints</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fexport_005fcrl_005fdist_005fpoints"><code>gnutls_x509_ext_export_crl_dist_points</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fexport_005fkey_005fpurposes"><code>gnutls_x509_ext_export_key_purposes</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fexport_005fkey_005fusage"><code>gnutls_x509_ext_export_key_usage</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fexport_005fname_005fconstraints"><code>gnutls_x509_ext_export_name_constraints</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fexport_005fpolicies"><code>gnutls_x509_ext_export_policies</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fexport_005fprivate_005fkey_005fusage_005fperiod"><code>gnutls_x509_ext_export_private_key_usage_period</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fexport_005fproxy"><code>gnutls_x509_ext_export_proxy</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fexport_005fsubject_005falt_005fnames"><code>gnutls_x509_ext_export_subject_alt_names</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fexport_005fsubject_005fkey_005fid"><code>gnutls_x509_ext_export_subject_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fimport_005faia"><code>gnutls_x509_ext_import_aia</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fimport_005fauthority_005fkey_005fid"><code>gnutls_x509_ext_import_authority_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fimport_005fbasic_005fconstraints"><code>gnutls_x509_ext_import_basic_constraints</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fimport_005fcrl_005fdist_005fpoints"><code>gnutls_x509_ext_import_crl_dist_points</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fimport_005fkey_005fpurposes"><code>gnutls_x509_ext_import_key_purposes</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fimport_005fkey_005fusage"><code>gnutls_x509_ext_import_key_usage</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fimport_005fname_005fconstraints"><code>gnutls_x509_ext_import_name_constraints</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fimport_005fpolicies"><code>gnutls_x509_ext_import_policies</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fimport_005fprivate_005fkey_005fusage_005fperiod"><code>gnutls_x509_ext_import_private_key_usage_period</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fimport_005fproxy"><code>gnutls_x509_ext_import_proxy</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fimport_005fsubject_005falt_005fnames"><code>gnutls_x509_ext_import_subject_alt_names</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fimport_005fsubject_005fkey_005fid"><code>gnutls_x509_ext_import_subject_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fext_005fprint"><code>gnutls_x509_ext_print</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fkey_005fpurpose_005fdeinit"><code>gnutls_x509_key_purpose_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fkey_005fpurpose_005fget"><code>gnutls_x509_key_purpose_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fkey_005fpurpose_005finit"><code>gnutls_x509_key_purpose_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fkey_005fpurpose_005fset"><code>gnutls_x509_key_purpose_set</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fname_005fconstraints_005fadd_005fexcluded"><code>gnutls_x509_name_constraints_add_excluded</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fname_005fconstraints_005fadd_005fpermitted"><code>gnutls_x509_name_constraints_add_permitted</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fname_005fconstraints_005fcheck"><code>gnutls_x509_name_constraints_check</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fname_005fconstraints_005fcheck_005fcrt"><code>gnutls_x509_name_constraints_check_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fname_005fconstraints_005fdeinit"><code>gnutls_x509_name_constraints_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fname_005fconstraints_005fget_005fexcluded"><code>gnutls_x509_name_constraints_get_excluded</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fname_005fconstraints_005fget_005fpermitted"><code>gnutls_x509_name_constraints_get_permitted</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fname_005fconstraints_005finit"><code>gnutls_x509_name_constraints_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fothername_005fto_005fvirtual"><code>gnutls_x509_othername_to_virtual</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fpolicies_005fdeinit"><code>gnutls_x509_policies_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fpolicies_005fget"><code>gnutls_x509_policies_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fpolicies_005finit"><code>gnutls_x509_policies_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fpolicies_005fset"><code>gnutls_x509_policies_set</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fpolicy_005frelease"><code>gnutls_x509_policy_release</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fcpy"><code>gnutls_x509_privkey_cpy</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fdeinit"><code>gnutls_x509_privkey_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fexport"><code>gnutls_x509_privkey_export</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fexport2"><code>gnutls_x509_privkey_export2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fexport2_005fpkcs8"><code>gnutls_x509_privkey_export2_pkcs8</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fexport_005fdsa_005fraw"><code>gnutls_x509_privkey_export_dsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fexport_005fecc_005fraw"><code>gnutls_x509_privkey_export_ecc_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fexport_005fpkcs8"><code>gnutls_x509_privkey_export_pkcs8</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fexport_005frsa_005fraw"><code>gnutls_x509_privkey_export_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fexport_005frsa_005fraw2"><code>gnutls_x509_privkey_export_rsa_raw2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005ffix"><code>gnutls_x509_privkey_fix</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fgenerate"><code>gnutls_x509_privkey_generate</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fget_005fkey_005fid"><code>gnutls_x509_privkey_get_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fget_005fpk_005falgorithm"><code>gnutls_x509_privkey_get_pk_algorithm</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fget_005fpk_005falgorithm2"><code>gnutls_x509_privkey_get_pk_algorithm2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fimport"><code>gnutls_x509_privkey_import</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fimport2"><code>gnutls_x509_privkey_import2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Managing-encrypted-keys">Managing encrypted keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fimport2-1"><code>gnutls_x509_privkey_import2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fimport_005fdsa_005fraw"><code>gnutls_x509_privkey_import_dsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fimport_005fecc_005fraw"><code>gnutls_x509_privkey_import_ecc_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fimport_005fopenssl"><code>gnutls_x509_privkey_import_openssl</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Managing-encrypted-keys">Managing encrypted keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fimport_005fopenssl-1"><code>gnutls_x509_privkey_import_openssl</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fimport_005fpkcs8"><code>gnutls_x509_privkey_import_pkcs8</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fimport_005frsa_005fraw"><code>gnutls_x509_privkey_import_rsa_raw</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fimport_005frsa_005fraw2"><code>gnutls_x509_privkey_import_rsa_raw2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005finit"><code>gnutls_x509_privkey_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fsec_005fparam"><code>gnutls_x509_privkey_sec_param</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fset_005fpin_005ffunction"><code>gnutls_x509_privkey_set_pin_function</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fsign_005fdata"><code>gnutls_x509_privkey_sign_data</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fsign_005fhash"><code>gnutls_x509_privkey_sign_hash</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Compatibility-API">Compatibility API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005fprivkey_005fverify_005fparams"><code>gnutls_x509_privkey_verify_params</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005frdn_005fget"><code>gnutls_x509_rdn_get</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005frdn_005fget_005fby_005foid"><code>gnutls_x509_rdn_get_by_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005frdn_005fget_005foid"><code>gnutls_x509_rdn_get_oid</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005fcas"><code>gnutls_x509_trust_list_add_cas</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-X_002e509-certificate-paths">Verifying X.509 certificate paths</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005fcas-1"><code>gnutls_x509_trust_list_add_cas</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005fcrls"><code>gnutls_x509_trust_list_add_crls</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-X_002e509-certificate-paths">Verifying X.509 certificate paths</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005fcrls-1"><code>gnutls_x509_trust_list_add_crls</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005fnamed_005fcrt"><code>gnutls_x509_trust_list_add_named_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-X_002e509-certificate-paths">Verifying X.509 certificate paths</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005fnamed_005fcrt-1"><code>gnutls_x509_trust_list_add_named_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005fsystem_005ftrust"><code>gnutls_x509_trust_list_add_system_trust</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-X_002e509-certificate-paths">Verifying X.509 certificate paths</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005fsystem_005ftrust-1"><code>gnutls_x509_trust_list_add_system_trust</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005fdir"><code>gnutls_x509_trust_list_add_trust_dir</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005ffile"><code>gnutls_x509_trust_list_add_trust_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-X_002e509-certificate-paths">Verifying X.509 certificate paths</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005ffile-1"><code>gnutls_x509_trust_list_add_trust_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005fmem"><code>gnutls_x509_trust_list_add_trust_mem</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-X_002e509-certificate-paths">Verifying X.509 certificate paths</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fadd_005ftrust_005fmem-1"><code>gnutls_x509_trust_list_add_trust_mem</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fdeinit"><code>gnutls_x509_trust_list_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fget_005fissuer"><code>gnutls_x509_trust_list_get_issuer</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fget_005fissuer_005fby_005fdn"><code>gnutls_x509_trust_list_get_issuer_by_dn</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fget_005fissuer_005fby_005fsubject_005fkey_005fid"><code>gnutls_x509_trust_list_get_issuer_by_subject_key_id</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005finit"><code>gnutls_x509_trust_list_init</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fiter_005fdeinit"><code>gnutls_x509_trust_list_iter_deinit</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fiter_005fget_005fca"><code>gnutls_x509_trust_list_iter_get_ca</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fremove_005fcas"><code>gnutls_x509_trust_list_remove_cas</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fremove_005ftrust_005ffile"><code>gnutls_x509_trust_list_remove_trust_file</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fremove_005ftrust_005fmem"><code>gnutls_x509_trust_list_remove_trust_mem</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt"><code>gnutls_x509_trust_list_verify_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-X_002e509-certificate-paths">Verifying X.509 certificate paths</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt-1"><code>gnutls_x509_trust_list_verify_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt2"><code>gnutls_x509_trust_list_verify_crt2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-X_002e509-certificate-paths">Verifying X.509 certificate paths</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fverify_005fcrt2-1"><code>gnutls_x509_trust_list_verify_crt2</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fverify_005fnamed_005fcrt"><code>gnutls_x509_trust_list_verify_named_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-X_002e509-certificate-paths">Verifying X.509 certificate paths</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_005fx509_005ftrust_005flist_005fverify_005fnamed_005fcrt-1"><code>gnutls_x509_trust_list_verify_named_crt</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table><tr><th valign="top">Jump to: &nbsp; </th><td><a class="summary-letter" href="#Function-and-Data-Index_fn_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter" href="#Function-and-Data-Index_fn_letter-G"><b>G</b></a>
 &nbsp; 
</td></tr></table>

<hr>
<a name="Concept-Index"></a>
<div class="header">
<p>
Previous: <a href="#Function-and-Data-Index" accesskey="p" rel="prev">Function and Data Index</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Concept-Index-1"></a>
<h2 class="unnumbered">Concept Index</h2>

<table><tr><th valign="top">Jump to: &nbsp; </th><td><a class="summary-letter" href="#Concept-Index_cp_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-B"><b>B</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-D"><b>D</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-I"><b>I</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-K"><b>K</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-M"><b>M</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-O"><b>O</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-V"><b>V</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-X"><b>X</b></a>
 &nbsp; 
</td></tr></table>
<table class="index-cp" border="0">
<tr><td></td><th align="left">Index Entry</th><td>&nbsp;</td><th align="left"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-A">A</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-abstract-types">abstract types</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Abstract-key-types">Abstract key types</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-alert-protocol">alert protocol</a>:</td><td>&nbsp;</td><td valign="top"><a href="#The-TLS-Alert-Protocol">The TLS Alert Protocol</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-ALPN">ALPN</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Application-Layer-Protocol-Negotiation-_0028ALPN_0029">Application Layer Protocol Negotiation (ALPN)</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-anonymous-authentication">anonymous authentication</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Anonymous-authentication">Anonymous authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-API-reference">API reference</a>:</td><td>&nbsp;</td><td valign="top"><a href="#API-reference">API reference</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Application-Layer-Protocol-Negotiation">Application Layer Protocol Negotiation</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Application-Layer-Protocol-Negotiation-_0028ALPN_0029">Application Layer Protocol Negotiation (ALPN)</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Application_002dspecific-keys">Application-specific keys</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Application_002dspecific-keys">Application-specific keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-authentication-methods">authentication methods</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Authentication-methods">Authentication methods</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-B">B</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-bad_005frecord_005fmac">bad_record_mac</a>:</td><td>&nbsp;</td><td valign="top"><a href="#On-Record-Padding">On Record Padding</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-C">C</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-callback-functions">callback functions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Callback-functions">Callback functions</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-certificate-authentication">certificate authentication</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-authentication">Certificate authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-certificate-authentication-1">certificate authentication</a>:</td><td>&nbsp;</td><td valign="top"><a href="#More-on-certificate-authentication">More on certificate authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-certificate-requests">certificate requests</a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-10-certificate-requests">PKCS 10 certificate requests</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-certificate-revocation-lists">certificate revocation lists</a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKIX-certificate-revocation-lists">PKIX certificate revocation lists</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-certificate-status">certificate status</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-certificate-status-checking">OCSP certificate status checking</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Certificate-status-request">Certificate status request</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-status-request">OCSP status request</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Certificate-verification">Certificate verification</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Advanced-certificate-verification">Advanced certificate verification</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-certification">certification</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certification">Certification</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-certtool"><code>certtool</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#certtool-Invocation">certtool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-certtool-help">certtool help</a>:</td><td>&nbsp;</td><td valign="top"><a href="#certtool-Invocation">certtool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-channel-bindings">channel bindings</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Channel-Bindings">Channel Bindings</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-ciphersuites">ciphersuites</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Supported-ciphersuites">Supported ciphersuites</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-client-certificate-authentication">client certificate authentication</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Client-Authentication">Client Authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-compression-algorithms">compression algorithms</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Compression-algorithms-used-in-the-record-layer">Compression algorithms used in the record layer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-contributing">contributing</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Contributing">Contributing</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-CRL">CRL</a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKIX-certificate-revocation-lists">PKIX certificate revocation lists</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-D">D</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-DANE">DANE</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-a-certificate-using-DANE">Verifying a certificate using DANE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-DANE-1">DANE</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-verification">Certificate verification</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-danetool"><code>danetool</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#danetool-Invocation">danetool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-danetool-help">danetool help</a>:</td><td>&nbsp;</td><td valign="top"><a href="#danetool-Invocation">danetool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-deriving-keys">deriving keys</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Deriving-keys-for-other-applications_002fprotocols">Deriving keys for other applications/protocols</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-digital-signatures">digital signatures</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Digital-signatures">Digital signatures</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-DNSSEC">DNSSEC</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-a-certificate-using-DANE">Verifying a certificate using DANE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-DNSSEC-1">DNSSEC</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-verification">Certificate verification</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-download">download</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Downloading-and-installing">Downloading and installing</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-E">E</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-Encrypted-keys">Encrypted keys</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Managing-encrypted-keys">Managing encrypted keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-error-codes">error codes</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Error-codes">Error codes</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-example-programs">example programs</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GnuTLS-application-examples">GnuTLS application examples</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-examples">examples</a>:</td><td>&nbsp;</td><td valign="top"><a href="#GnuTLS-application-examples">GnuTLS application examples</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-exporting-keying-material">exporting keying material</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Deriving-keys-for-other-applications_002fprotocols">Deriving keys for other applications/protocols</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-F">F</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-FDL_002c-GNU-Free-Documentation-License">FDL, GNU Free Documentation License</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Copying-Information">Copying Information</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-file-signing">file signing</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Public-key-algorithms">Public key algorithms</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fork">fork</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Sessions-and-fork">Sessions and fork</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-G">G</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-generating-parameters">generating parameters</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Parameter-generation">Parameter generation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_002dcli"><code>gnutls-cli</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#gnutls_002dcli-Invocation">gnutls-cli Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_002dcli-help">gnutls-cli help</a>:</td><td>&nbsp;</td><td valign="top"><a href="#gnutls_002dcli-Invocation">gnutls-cli Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_002dcli_002ddebug"><code>gnutls-cli-debug</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#gnutls_002dcli_002ddebug-Invocation">gnutls-cli-debug Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_002dcli_002ddebug-help">gnutls-cli-debug help</a>:</td><td>&nbsp;</td><td valign="top"><a href="#gnutls_002dcli_002ddebug-Invocation">gnutls-cli-debug Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_002dserv"><code>gnutls-serv</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#gnutls_002dserv-Invocation">gnutls-serv Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-gnutls_002dserv-help">gnutls-serv help</a>:</td><td>&nbsp;</td><td valign="top"><a href="#gnutls_002dserv-Invocation">gnutls-serv Invocation</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-H">H</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-hacking">hacking</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Contributing">Contributing</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-handshake-protocol">handshake protocol</a>:</td><td>&nbsp;</td><td valign="top"><a href="#The-TLS-Handshake-Protocol">The TLS Handshake Protocol</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-hardware-security-modules">hardware security modules</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Smart-cards-and-HSMs">Smart cards and HSMs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-hardware-tokens">hardware tokens</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Smart-cards-and-HSMs">Smart cards and HSMs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-hash-functions">hash functions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Hash-and-MAC-functions">Hash and MAC functions</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-heartbeat">heartbeat</a>:</td><td>&nbsp;</td><td valign="top"><a href="#HeartBeat">HeartBeat</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-HMAC-functions">HMAC functions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Hash-and-MAC-functions">Hash and MAC functions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-I">I</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-installation">installation</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Downloading-and-installing">Downloading and installing</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-installation-1">installation</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Installing-for-a-software-distribution">Installing for a software distribution</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-internal-architecture">internal architecture</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Internal-architecture-of-GnuTLS">Internal architecture of GnuTLS</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-isolated-mode">isolated mode</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Running-in-a-sandbox">Running in a sandbox</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-K">K</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-key-extraction">key extraction</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Deriving-keys-for-other-applications_002fprotocols">Deriving keys for other applications/protocols</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Key-pinning">Key pinning</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-a-certificate-using-trust-on-first-use-authentication">Verifying a certificate using trust on first use authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Key-pinning-1">Key pinning</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-verification">Certificate verification</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-key-sizes">key sizes</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Selecting-cryptographic-key-sizes">Selecting cryptographic key sizes</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-keying-material-exporters">keying material exporters</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Deriving-keys-for-other-applications_002fprotocols">Deriving keys for other applications/protocols</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-M">M</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-MAC-functions">MAC functions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Hash-and-MAC-functions">Hash and MAC functions</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-maximum-fragment-length">maximum fragment length</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Maximum-fragment-length-negotiation">Maximum fragment length negotiation</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-O">O</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-OCSP">OCSP</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-certificate-status-checking">OCSP certificate status checking</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-OCSP-Functions">OCSP Functions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-API">OCSP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-OCSP-status-request">OCSP status request</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-status-request">OCSP status request</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-ocsptool"><code>ocsptool</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#ocsptool-Invocation">ocsptool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-ocsptool-help">ocsptool help</a>:</td><td>&nbsp;</td><td valign="top"><a href="#ocsptool-Invocation">ocsptool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Online-Certificate-Status-Protocol">Online Certificate Status Protocol</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OCSP-certificate-status-checking">OCSP certificate status checking</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-OpenPGP-API">OpenPGP API</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-API">OpenPGP API</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-OpenPGP-certificates">OpenPGP certificates</a>:</td><td>&nbsp;</td><td valign="top"><a href="#OpenPGP-certificates">OpenPGP certificates</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-OpenPGP-server">OpenPGP server</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Echo-server-with-OpenPGP-authentication">Echo server with OpenPGP authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-OpenSSL">OpenSSL</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Compatibility-with-the-OpenSSL-library">Compatibility with the OpenSSL library</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-OpenSSL-encrypted-keys">OpenSSL encrypted keys</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Managing-encrypted-keys">Managing encrypted keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-overriding-algorithms">overriding algorithms</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Overriding-algorithms">Overriding algorithms</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-P">P</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-p11tool"><code>p11tool</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#p11tool-Invocation">p11tool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-p11tool-help">p11tool help</a>:</td><td>&nbsp;</td><td valign="top"><a href="#p11tool-Invocation">p11tool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-parameter-generation">parameter generation</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Parameter-generation">Parameter generation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-PCT">PCT</a>:</td><td>&nbsp;</td><td valign="top"><a href="#On-SSL-2-and-older-protocols">On SSL 2 and older protocols</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-PKCS-_002310">PKCS #10</a>:</td><td>&nbsp;</td><td valign="top"><a href="#PKCS-10-certificate-requests">PKCS 10 certificate requests</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-PKCS-_002311-tokens">PKCS #11 tokens</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Smart-cards-and-HSMs">Smart cards and HSMs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-PKCS-_002312">PKCS #12</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Managing-encrypted-keys">Managing encrypted keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-PKCS-_00237">PKCS #7</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Public-key-algorithms">Public key algorithms</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-PKCS-_00238">PKCS #8</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Managing-encrypted-keys">Managing encrypted keys</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Priority-strings">Priority strings</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Priority-Strings">Priority Strings</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-PSK-authentication">PSK authentication</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Authentication-using-PSK">Authentication using PSK</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-psktool"><code>psktool</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#psktool-Invocation">psktool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-psktool-help">psktool help</a>:</td><td>&nbsp;</td><td valign="top"><a href="#psktool-Invocation">psktool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-public-key-algorithms">public key algorithms</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Public-key-algorithms">Public key algorithms</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-R">R</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-random-numbers">random numbers</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Random-number-generation">Random number generation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-reauthentication">reauthentication</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Re_002dauthentication">Re-authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-record-padding">record padding</a>:</td><td>&nbsp;</td><td valign="top"><a href="#On-Record-Padding">On Record Padding</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-record-protocol">record protocol</a>:</td><td>&nbsp;</td><td valign="top"><a href="#The-TLS-record-protocol">The TLS record protocol</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-renegotiation">renegotiation</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Safe-renegotiation">Safe renegotiation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-renegotiation-1">renegotiation</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Re_002dauthentication">Re-authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-reporting-bugs">reporting bugs</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Bug-Reports">Bug Reports</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-resuming-sessions">resuming sessions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Resuming-Sessions">Resuming Sessions</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-resuming-sessions-1">resuming sessions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Session-resumption">Session resumption</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-S">S</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-safe-renegotiation">safe renegotiation</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Safe-renegotiation">Safe renegotiation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-seccomp">seccomp</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Running-in-a-sandbox">Running in a sandbox</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Secure-RTP">Secure RTP</a>:</td><td>&nbsp;</td><td valign="top"><a href="#SRTP">SRTP</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-server-name-indication">server name indication</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Server-name-indication">Server name indication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-session-resumption">session resumption</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Resuming-Sessions">Resuming Sessions</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-session-resumption-1">session resumption</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Session-resumption">Session resumption</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-session-tickets">session tickets</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Session-tickets">Session tickets</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Smart-card-example">Smart card example</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Client-using-a-smart-card-with-TLS">Client using a smart card with TLS</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-smart-cards">smart cards</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Smart-cards-and-HSMs">Smart cards and HSMs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-SRP-authentication">SRP authentication</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Authentication-using-SRP">Authentication using SRP</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-srptool"><code>srptool</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#srptool-Invocation">srptool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-srptool-help">srptool help</a>:</td><td>&nbsp;</td><td valign="top"><a href="#srptool-Invocation">srptool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-SRTP">SRTP</a>:</td><td>&nbsp;</td><td valign="top"><a href="#SRTP">SRTP</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-SSH_002dstyle-authentication">SSH-style authentication</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-a-certificate-using-trust-on-first-use-authentication">Verifying a certificate using trust on first use authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-SSH_002dstyle-authentication-1">SSH-style authentication</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-verification">Certificate verification</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-SSL-2">SSL 2</a>:</td><td>&nbsp;</td><td valign="top"><a href="#On-SSL-2-and-older-protocols">On SSL 2 and older protocols</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Supplemental-data">Supplemental data</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Extensions-and-Supplemental-Data">Extensions and Supplemental Data</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-symmetric-algorithms">symmetric algorithms</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Symmetric-algorithms">Symmetric algorithms</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-symmetric-cryptography">symmetric cryptography</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Symmetric-algorithms">Symmetric algorithms</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-symmetric-encryption-algorithms">symmetric encryption algorithms</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Encryption-algorithms-used-in-the-record-layer">Encryption algorithms used in the record layer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-System_002dspecific-keys">System-specific keys</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Application_002dspecific-keys">Application-specific keys</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-T">T</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-thread-safety">thread safety</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Thread-safety">Thread safety</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-tickets">tickets</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Session-tickets">Session tickets</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-TLS-extensions">TLS extensions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#TLS-Extensions">TLS Extensions</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-TLS-extensions-1">TLS extensions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Maximum-fragment-length-negotiation">Maximum fragment length negotiation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-TLS-extensions-2">TLS extensions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Server-name-indication">Server name indication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-TLS-extensions-3">TLS extensions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Session-tickets">Session tickets</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-TLS-extensions-4">TLS extensions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#HeartBeat">HeartBeat</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-TLS-layers">TLS layers</a>:</td><td>&nbsp;</td><td valign="top"><a href="#TLS-layers">TLS layers</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-TPM">TPM</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Trusted-Platform-Module">Trusted Platform Module</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-tpmtool"><code>tpmtool</code></a>:</td><td>&nbsp;</td><td valign="top"><a href="#tpmtool-Invocation">tpmtool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-tpmtool-help">tpmtool help</a>:</td><td>&nbsp;</td><td valign="top"><a href="#tpmtool-Invocation">tpmtool Invocation</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-transport-layer">transport layer</a>:</td><td>&nbsp;</td><td valign="top"><a href="#The-transport-layer">The transport layer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-transport-protocol">transport protocol</a>:</td><td>&nbsp;</td><td valign="top"><a href="#The-transport-layer">The transport layer</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Trust-on-first-use">Trust on first use</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-a-certificate-using-trust-on-first-use-authentication">Verifying a certificate using trust on first use authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Trust-on-first-use-1">Trust on first use</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Certificate-verification">Certificate verification</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-trusted-platform-module">trusted platform module</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Trusted-Platform-Module">Trusted Platform Module</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-U">U</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-upgrading">upgrading</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Upgrading-from-previous-versions">Upgrading from previous versions</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-V">V</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-verifying-certificate-paths">verifying certificate paths</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-X_002e509-certificate-paths">Verifying X.509 certificate paths</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-verifying-certificate-paths-1">verifying certificate paths</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-a-certificate-in-the-context-of-TLS-session">Verifying a certificate in the context of TLS session</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-verifying-certificate-paths-2">verifying certificate paths</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-a-certificate-using-trust-on-first-use-authentication">Verifying a certificate using trust on first use authentication</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-verifying-certificate-paths-3">verifying certificate paths</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verifying-a-certificate-using-DANE">Verifying a certificate using DANE</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-verifying-certificate-with-pkcs11">verifying certificate with pkcs11</a>:</td><td>&nbsp;</td><td valign="top"><a href="#Verification-using-PKCS11">Verification using PKCS11</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-Index_cp_letter-X">X</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-X_002e509-certificate-name">X.509 certificate name</a>:</td><td>&nbsp;</td><td valign="top"><a href="#X_002e509-certificate-names">X.509 certificate names</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-X_002e509-certificates">X.509 certificates</a>:</td><td>&nbsp;</td><td valign="top"><a href="#X_002e509-certificates">X.509 certificates</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-X_002e509-distinguished-name">X.509 distinguished name</a>:</td><td>&nbsp;</td><td valign="top"><a href="#X_002e509-distinguished-names">X.509 distinguished names</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-X_002e509-extensions">X.509 extensions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#X_002e509-extensions">X.509 extensions</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-X_002e509-Functions">X.509 Functions</a>:</td><td>&nbsp;</td><td valign="top"><a href="#X509-certificate-API">X509 certificate API</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table><tr><th valign="top">Jump to: &nbsp; </th><td><a class="summary-letter" href="#Concept-Index_cp_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-B"><b>B</b></a>
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<a class="summary-letter" href="#Concept-Index_cp_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-D"><b>D</b></a>
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<a class="summary-letter" href="#Concept-Index_cp_letter-E"><b>E</b></a>
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<a class="summary-letter" href="#Concept-Index_cp_letter-F"><b>F</b></a>
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<a class="summary-letter" href="#Concept-Index_cp_letter-G"><b>G</b></a>
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<a class="summary-letter" href="#Concept-Index_cp_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-I"><b>I</b></a>
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<a class="summary-letter" href="#Concept-Index_cp_letter-K"><b>K</b></a>
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<a class="summary-letter" href="#Concept-Index_cp_letter-M"><b>M</b></a>
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<a class="summary-letter" href="#Concept-Index_cp_letter-O"><b>O</b></a>
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<a class="summary-letter" href="#Concept-Index_cp_letter-P"><b>P</b></a>
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<a class="summary-letter" href="#Concept-Index_cp_letter-R"><b>R</b></a>
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<a class="summary-letter" href="#Concept-Index_cp_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-T"><b>T</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-V"><b>V</b></a>
 &nbsp; 
<a class="summary-letter" href="#Concept-Index_cp_letter-X"><b>X</b></a>
 &nbsp; 
</td></tr></table>

<div class="footnote">
<hr>
<h4 class="footnotes-heading">Footnotes</h4>

<h3><a name="FOOT1" href="#DOCF1">(1)</a></h3>
<p>Needed
to use RFC6125 name comparison in internationalized domains.</p>
<h3><a name="FOOT2" href="#DOCF2">(2)</a></h3>
<p><a href="http://p11-glue.freedesktop.org/doc/p11-kit/trust-module.html">http://p11-glue.freedesktop.org/doc/p11-kit/trust-module.html</a></p>
<h3><a name="FOOT3" href="#DOCF3">(3)</a></h3>
<p>IETF, or Internet Engineering Task Force,
is a large open international community of network designers,
operators, vendors, and researchers concerned with the evolution of
the Internet architecture and the smooth operation of the Internet.
It is open to any interested individual.</p>
<h3><a name="FOOT4" href="#DOCF4">(4)</a></h3>
<p>If this is not possible then please consult <a href="#Interoperability">Interoperability</a>.</p>
<h3><a name="FOOT5" href="#DOCF5">(5)</a></h3>
<p>MAC stands for Message Authentication Code. It can be described as a keyed hash algorithm. See RFC2104.</p>
<h3><a name="FOOT6" href="#DOCF6">(6)</a></h3>
<p>See also the Server Name Indication extension on
<a href="#serverind">serverind</a>.</p>
<h3><a name="FOOT7" href="#DOCF7">(7)</a></h3>
<p>See LDAP, IMAP etc.</p>
<h3><a name="FOOT8" href="#DOCF8">(8)</a></h3>
<p>see <a href="http://p11-glue.freedesktop.org/trust-module.html">http://p11-glue.freedesktop.org/trust-module.html</a>.</p>
<h3><a name="FOOT9" href="#DOCF9">(9)</a></h3>
<p><a href="http://www.gnupg.org/related_software/gpgme/">http://www.gnupg.org/related_software/gpgme/</a></p>
<h3><a name="FOOT10" href="#DOCF10">(10)</a></h3>
<p>For example, OpenSC-supported cards.</p>
<h3><a name="FOOT11" href="#DOCF11">(11)</a></h3>
<p><a href="http://p11-glue.freedesktop.org/trust-module.html">http://p11-glue.freedesktop.org/trust-module.html</a></p>
<h3><a name="FOOT12" href="#DOCF12">(12)</a></h3>
<p><a href="http://p11-glue.freedesktop.org/">http://p11-glue.freedesktop.org/</a></p>
<h3><a name="FOOT13" href="#DOCF13">(13)</a></h3>
<p>For
example when an open session is to be reinitialized, but the PIN is not available
to GnuTLS (e.g., it was entered at a pinpad).</p>
<h3><a name="FOOT14" href="#DOCF14">(14)</a></h3>
<p>The first message in a <acronym>TLS</acronym> handshake</p>
<h3><a name="FOOT15" href="#DOCF15">(15)</a></h3>
<p>The original behavior of requiring explicit initialization can obtained by setting the
GNUTLS_NO_EXPLICIT_INIT environment variable to 1, or by using the macro GNUTLS_SKIP_GLOBAL_INIT
in a global section of your program.</p>
<h3><a name="FOOT16" href="#DOCF16">(16)</a></h3>
<p>A key of 128 bits or 16 bytes should be sufficient for this purpose.</p>
<h3><a name="FOOT17" href="#DOCF17">(17)</a></h3>
<p>The default is <code>/etc/gnutls/default-priorities</code>.</p>
<h3><a name="FOOT18" href="#DOCF18">(18)</a></h3>
<p>It depends on the group used.  Primes with
lesser bits are always faster, but also easier to break.  See <a href="#Selecting-cryptographic-key-sizes">Selecting cryptographic key sizes</a>
for the acceptable security levels.</p>
<h3><a name="FOOT19" href="#DOCF19">(19)</a></h3>
<p>See <a href="http://www.lysator.liu.se/~nisse/nettle/">http://www.lysator.liu.se/~nisse/nettle/</a>.</p>
<h3><a name="FOOT20" href="#DOCF20">(20)</a></h3>
<p>such as the
<code>gnutls_certificate_credentials_t</code> structures</p>
<h3><a name="FOOT21" href="#DOCF21">(21)</a></h3>
<p>See
<a href="http://lists.gnu.org/archive/html/gnutls-devel/2011-02/msg00079.html">http://lists.gnu.org/archive/html/gnutls-devel/2011-02/msg00079.html</a>.</p>
<h3><a name="FOOT22" href="#DOCF22">(22)</a></h3>
<p>Check <a href="http://home.gna.org/cryptodev-linux/">http://home.gna.org/cryptodev-linux/</a> 
for the Linux kernel implementation of <code>/dev/crypto</code>.</p>
</div>
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