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<hr>
<a name="Cryptographic-API-1"></a>
<h3 class="section">E.13 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.
</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. For block ciphers the <code>ctext_len</code> must be
a multiple of the block size. For the supported ciphers the plaintext
data length will equal the ciphertext size.
</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. For block ciphers the <code>ptext_len</code> must be
a multiple of the block size. For the supported ciphers the encrypted
data length will equal the plaintext size.
</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>unsigned</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>unsigned</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>unsigned</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_005fdecode_005fber_005fdigest_005finfo-1"></a>
<h4 class="subheading">gnutls_decode_ber_digest_info</h4>
<a name="gnutls_005fdecode_005fber_005fdigest_005finfo"></a><dl>
<dt><a name="index-gnutls_005fdecode_005fber_005fdigest_005finfo"></a>Function: <em>int</em> <strong>gnutls_decode_ber_digest_info</strong> <em>(const gnutls_datum_t * <var>info</var>, gnutls_digest_algorithm_t * <var>hash</var>, unsigned char * <var>digest</var>, unsigned int * <var>digest_size</var>)</em></dt>
<dd><p><var>info</var>: an RSA BER encoded DigestInfo structure
</p>
<p><var>hash</var>: will contain the hash algorithm of the structure
</p>
<p><var>digest</var>: will contain the hash output of the structure
</p>
<p><var>digest_size</var>: will contain the hash size of the structure; initially must hold the maximum size of <code>digest</code>
</p>
<p>This function will parse an RSA PKCS<code>1</code> 1.5 DigestInfo structure
and report the hash algorithm used as well as the digest data.
</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> 3.5.0
</p></dd></dl>
<a name="gnutls_005fencode_005fber_005fdigest_005finfo-1"></a>
<h4 class="subheading">gnutls_encode_ber_digest_info</h4>
<a name="gnutls_005fencode_005fber_005fdigest_005finfo"></a><dl>
<dt><a name="index-gnutls_005fencode_005fber_005fdigest_005finfo"></a>Function: <em>int</em> <strong>gnutls_encode_ber_digest_info</strong> <em>(gnutls_digest_algorithm_t <var>hash</var>, const gnutls_datum_t * <var>digest</var>, gnutls_datum_t * <var>output</var>)</em></dt>
<dd><p><var>hash</var>: the hash algorithm that was used to get the digest
</p>
<p><var>digest</var>: must contain the digest data
</p>
<p><var>output</var>: will contain the allocated DigestInfo BER encoded data
</p>
<p>This function will encode the provided digest data, and its
algorithm into an RSA PKCS<code>1</code> 1.5 DigestInfo structure.
</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> 3.5.0
</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>unsigned</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>unsigned</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>
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