path: root/doc/protocol/draft-badra-tls-psk-new-mac-aes-gcm-02.txt

TLS Working Group                                         Mohamad Badra 
Internet Draft                                         LIMOS Laboratory 
Intended status: Standards Track                         April 30, 2008 
Expires: October 2008 
                                    
 
                                      
   Pre-Shared Key Cipher Suites for Transport Layer Security (TLS) with 
                  SHA-256/384 and AES Galois Counter Mode  
                draft-badra-tls-psk-new-mac-aes-gcm-02.txt 


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Copyright Notice 

   Copyright (C) The IETF Trust (2008). 

Abstract 

   RFC 4279 and RFC 4785 describe pre-shared key cipher suites for 
   Transport Layer Security (TLS).  However, all those cipher suites 
   use SHA-1 as their MAC algorithm.  This document describes a set of 
   cipher suites for TLS/DTLS which uses stronger digest algorithms 

 
 
 
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   (i.e., SHA-256 or SHA-384) and another which uses the Advanced 
   Encryption Standard (AES) in Galois Counter Mode (GCM). 

Table of Contents 

    
   1. Introduction...................................................3 
      1.1. Conventions used in this document.........................3 
   2. PSK, DHE_PSK and RSA_PSK Key Exchange Algorithms with AES-GCM..3 
   3. PSK, DHE_PSK and RSA_PSK Key Exchange with SHA-256/384.........4 
      3.1. PSK Key Exchange Algorithm with SHA-256/384...............4 
      3.2. DHE_PSK Key Exchange Algorithm with SHA-256/384...........5 
      3.3. RSA_PSK Key Exchange Algorithm with SHA-256/384...........5 
   4. Security Considerations........................................5 
   5. IANA Considerations............................................6 
   6. Acknowledgments................................................6 
   7. References.....................................................6 
      7.1. Normative References......................................6 
      7.2. Informative References....................................7 
   Author's Addresses................................................8 
   Full Copyright Statement..........................................8 
   Intellectual Property.............................................8 
   Acknowledgment....................................................9 
    























 
 
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1. Introduction 

   TLS 1.2 [I-D.ietf-tls-rfc4346-bis], adds support for authenticated 
   encryption with additional data (AEAD) cipher modes [RFC5116]. This 
   document describes the use of Advanced Encryption Standard (AES) 
   [AES] in Galois Counter Mode (GCM) [GCM] (AES-GCM) with various pre-
   shared key (PSK) key exchange mechanisms ([RFC4279] and [RFC4785]) 
   as a cipher suite for Transport Layer Security (TLS).  

   This document also specifies PSK cipher suites for TLS which replace 
   SHA-1 by SHA-256 or SHA-384.  RFC 4279 [RFC4279] and RFC 4785 
   [RFC4785] describe PSK cipher suites for TLS.  However, all of the 
   RFC 4279 and the RFC 4785 cipher suites use HMAC-SHA1 as their MAC 
   algorithm.  Due to recent analytic work on SHA-1 [Wang05], the IETF 
   is gradually moving away from SHA-1 and towards stronger hash 
   algorithms. 

   ECC based cipher suites with SHA-256/384 and AES-GCM are defined in 
   [I-D.ietf-tls-ecc-new-mac]; RSA, DSS and Diffie-Hellman based cipher 
   suites are specified in [I-D.ietf-tls-rsa-aes-gcm].  The reader is 
   expected to become familiar with these two memos prior to studying 
   this document. 

1.1. Conventions used in this document  

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 
   document are to be interpreted as described in [RFC2119]. 

2. PSK, DHE_PSK and RSA_PSK Key Exchange Algorithms with AES-GCM 

   The following eight cipher suites use the new authenticated 
   encryption modes defined in TLS 1.2 with AES in Galois Counter Mode 
   (GCM) [GCM].  The cipher suites with DHE_PSK key exchange algorithm 
   (TLS_DHE_PSK_WITH_AES_128_GCM_SHA256 and 
   TLS_DHE_PSK_WITH_AES_128_GCM_SHA348) provide Perfect Forward Secrecy 
   (PFS). 

      CipherSuite TLS_PSK_WITH_AES_128_GCM_SHA256      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_AES_258_GCM_SHA256      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_AES_128_GCM_SHA384      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_AES_256_GCM_SHA384      = {0xXX,0xXX}; 
      CipherSuite TLS_DHE_PSK_WITH_AES_128_GCM_SHA256  = {0xXX,0xXX}; 
      CipherSuite TLS_DHE_PSK_WITH_AES_256_GCM_SHA384  = {0xXX,0xXX}; 
      CipherSuite TLS_RSA_PSK_WITH_AES_128_GCM_SHA256  = {0xXX,0xXX}; 
      CipherSuite TLS_RSA_PSK_WITH_AES_256_GCM_SHA384  = {0xXX,0xXX}; 

 
 
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   These cipher suites use authenticated encryption with additional 
   data (AEAD) algorithms AEAD_AES_128_GCM and AEAD_AES_256_GCM 
   described in RFC 5116.  GCM is used as described in [I-D.ietf-tls-
   rsa-aes-gcm]. 

   The PSK, DHE_PSK and RSA_PSK key exchanges are performed as defined 
   in [RFC4279]. 

   The PRF algorithms SHALL be as follows: 

       For cipher suites ending with _SHA256, the PRF is the TLS PRF  
       [I-D.ietf-tls-rfc4346-bis] with SHA-256 as the hash function. 

       For cipher suites ending with _SHA384, the PRF is the TLS PRF  
       [I-D.ietf-tls-rfc4346-bis] with SHA-384 as the hash function. 

   Implementations MUST send TLS Alert bad_record_mac for all types of 
   failures encountered in processing the AES-GCM algorithm. 

3. PSK, DHE_PSK and RSA_PSK Key Exchange with SHA-256/384 

   The cipher suites described in this section use AES [AES] in CBC 
   [CBC] mode with an HMAC-based MAC. 

3.1. PSK Key Exchange Algorithm with SHA-256/384 

      CipherSuite TLS_PSK_WITH_AES_128_CBC_SHA256      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_AES_256_CBC_SHA256      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_AES_128_CBC_SHA384      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_AES_256_CBC_SHA384      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_NULL_SHA256             = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_NULL_SHA384             = {0xXX,0xXX}; 

   The above six cipher suites are the same as the corresponding cipher 
   suites in RFC 4279 and RFC 4785 (with names ending in "_SHA" in 
   place of "_SHA256" or "_SHA384"), except for the hash and PRF 
   algorithms, which are SHA-256 and SHA-384 [SHS] as follows. 

   CipherSuite                              MAC             PRF 
   ------------                             ---             --- 
   TLS_PSK_WITH_AES_128_CBC_SHA256          HMAC-SHA-256    P_SHA-256 
   TLS_PSK_WITH_AES_128_CBC_SHA384          HMAC-SHA-384    P_SHA-384 
   TLS_PSK_WITH_AES_256_CBC_SHA256          HMAC-SHA-256    P_SHA-256 
   TLS_PSK_WITH_AES_256_CBC_SHA384          HMAC-SHA-384    P_SHA-384 
   TLS_PSK_WITH_NULL_SHA256                 HMAC-SHA-256    P_SHA-256 
   TLS_PSK_WITH_NULL_SHA384                 HMAC-SHA-384    P_SHA-384 

 
 
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3.2. DHE_PSK Key Exchange Algorithm with SHA-256/384 

      CipherSuite TLS_DHE_PSK_WITH_AES_128_CBC_SHA256  = {0xXX,0xXX};   
      CipherSuite TLS_DHE_PSK_WITH_AES_128_CBC_SHA384  = {0xXX,0xXX}; 
      CipherSuite TLS_DHE_PSK_WITH_AES_256_CBC_SHA256  = {0xXX,0xXX};     
      CipherSuite TLS_DHE_PSK_WITH_AES_256_CBC_SHA384  = {0xXX,0xXX}; 
      CipherSuite TLS_DHE_PSK_WITH_NULL_SHA256         = {0xXX,0xXX};     
      CipherSuite TLS_DHE_PSK_WITH_NULL_SHA384         = {0xXX,0xXX}; 

   The above six cipher suites are the same as the corresponding cipher 
   suites in RFC 4279 and RFC 4785 (with names ending in "_SHA" in 
   place of "_SHA256" or "_SHA384"), except for the hash and PRF 
   algorithms, which are SHA-256 and SHA-384 [SHS] as follows. 

   CipherSuite                              MAC             PRF 
   ------------                             ---             --- 
   TLS_DHE_PSK_WITH_AES_128_CBC_SHA256      HMAC-SHA-256    P_SHA-256 
   TLS_DHE_PSK_WITH_AES_128_CBC_SHA384      HMAC-SHA-384    P_SHA-384 
   TLS_DHE_PSK_WITH_AES_256_CBC_SHA256      HMAC-SHA-256    P_SHA-256 
   TLS_DHE_PSK_WITH_AES_256_CBC_SHA384      HMAC-SHA-384    P_SHA-384 

3.3. RSA_PSK Key Exchange Algorithm with SHA-256/384 

      CipherSuite TLS_RSA_PSK_WITH_AES_128_CBC_SHA256    = {0xXX,0xXX}; 
      CipherSuite TLS_RSA_PSK_WITH_AES_128_CBC_SHA384    = {0xXX,0xXX}; 
      CipherSuite TLS_RSA_PSK_WITH_AES_256_CBC_SHA256    = {0xXX,0xXX}; 
      CipherSuite TLS_RSA_PSK_WITH_AES_256_CBC_SHA384    = {0xXX,0xXX}; 

   The above four cipher suites are the same as the corresponding 
   cipher suites in RFC 4279 and RFC 4785 (with names ending in "_SHA" 
   in place of "_SHA256" or "_SHA384"), except for the hash and PRF 
   algorithms, which are SHA-256 and SHA-384 [SHS] as follows. 

   CipherSuite                              MAC             PRF 
   ------------                             ---             --- 
   TLS_RSA_PSK_WITH_AES_128_CBC_SHA256      HMAC-SHA-256    P_SHA-256 
   TLS_RSA_PSK_WITH_AES_128_CBC_SHA384      HMAC-SHA-384    P_SHA-384 
   TLS_RSA_PSK_WITH_AES_256_CBC_SHA256      HMAC-SHA-256    P_SHA-256 
   TLS_RSA_PSK_WITH_AES_256_CBC_SHA384      HMAC-SHA-384    P_SHA-384 

4. Security Considerations 

   The security considerations in RFC 4279, RFC 4758, and [I-D.ietf-
   tls-rsa-aes-gcm] apply to this document as well.  In addition, as 
   described in [I-D.ietf-tls-rsa-aes-gcm], these cipher suites may 
   only be used with TLS 1.2 or greater. 

 
 
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5. IANA Considerations 

   IANA has assigned the following values for the cipher suites defined 
   in this document: 

      CipherSuite TLS_PSK_WITH_AES_128_GCM_SHA256      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_AES_258_GCM_SHA256      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_AES_128_GCM_SHA384      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_AES_256_GCM_SHA384      = {0xXX,0xXX}; 
      CipherSuite TLS_DHE_PSK_WITH_AES_128_GCM_SHA256  = {0xXX,0xXX}; 
      CipherSuite TLS_DHE_PSK_WITH_AES_256_GCM_SHA384  = {0xXX,0xXX}; 
      CipherSuite TLS_RSA_PSK_WITH_AES_128_GCM_SHA256  = {0xXX,0xXX}; 
      CipherSuite TLS_RSA_PSK_WITH_AES_256_GCM_SHA384  = {0xXX,0xXX};    
      CipherSuite TLS_PSK_WITH_AES_128_CBC_SHA256      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_AES_256_CBC_SHA256      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_AES_128_CBC_SHA384      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_AES_256_CBC_SHA384      = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_NULL_SHA256             = {0xXX,0xXX}; 
      CipherSuite TLS_PSK_WITH_NULL_SHA384             = {0xXX,0xXX}; 
      CipherSuite TLS_DHE_PSK_WITH_AES_128_CBC_SHA256  = {0xXX,0xXX};   
      CipherSuite TLS_DHE_PSK_WITH_AES_128_CBC_SHA384  = {0xXX,0xXX}; 
      CipherSuite TLS_DHE_PSK_WITH_AES_256_CBC_SHA256  = {0xXX,0xXX};     
      CipherSuite TLS_DHE_PSK_WITH_AES_256_CBC_SHA384  = {0xXX,0xXX}; 
      CipherSuite TLS_DHE_PSK_WITH_NULL_SHA256         = {0xXX,0xXX};     
      CipherSuite TLS_DHE_PSK_WITH_NULL_SHA384         = {0xXX,0xXX}; 
      CipherSuite TLS_RSA_PSK_WITH_AES_128_CBC_SHA256  = {0xXX,0xXX}; 
      CipherSuite TLS_RSA_PSK_WITH_AES_128_CBC_SHA384  = {0xXX,0xXX}; 
      CipherSuite TLS_RSA_PSK_WITH_AES_256_CBC_SHA256  = {0xXX,0xXX}; 
      CipherSuite TLS_RSA_PSK_WITH_AES_256_CBC_SHA384  = {0xXX,0xXX}; 

6. Acknowledgments 

   This draft borrows heavily from [I-D.ietf-tls-ecc-new-mac] and [I-
   D.ietf-tls-rsa-aes-gcm]. 

7. References 

7.1. Normative References 

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 
             Requirement Levels", BCP 14, RFC 2119, March 1997. 

   [I-D.ietf-tls-rfc4346-bis] 
             Dierks, T. and E. Rescorla, "The Transport Layer Security 
             (TLS) Protocol Version 1.2", draft-ietf-tls-rfc4346-bis-
             10, work in progress, March 2008. 

 
 
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   [RFC5116] McGrew, D., "An Interface and Algorithms for Authenticated 
             Encryption", RFC 5116, January 2008.  

   [RFC4279] Eronen, P. and H. Tschofenig, "Pre-Shared Key Ciphersuites 
             for Transport Layer Security (TLS)", RFC 4279, December 
             2005.  

   [RFC4785] Blumenthal, U., Goel, P., "Pre-Shared Key (PSK) 
             Ciphersuites with NULL Encryption for Transport Layer 
             Security (TLS)", RFC 4785, January 2007. 

   [AES]     National Institute of Standards and Technology, 
             "Specification for the Advanced Encryption Standard 
             (AES)", FIPS 197, November 2001. 

   [SHS]     National Institute of Standards and Technology, "Secure 
             Hash Standard", FIPS 180-2, August 2002. 

   [CBC]     National Institute of Standards and Technology, 
             "Recommendation for Block Cipher Modes of Operation - 
             Methods and Techniques", SP 800-38A, December 2001. 

   [GCM]     National Institute of Standards and Technology, 
             "Recommendation for Block Cipher Modes of Operation: 
             Galois;/Counter Mode (GCM) for Confidentiality and 
             Authentication", SP 800-38D, November 2007. 

7.2. Informative References 

   [Wang05]  Wang, X., Yin, Y., and H. Yu, "Finding Collisions in the 
             Full SHA-1", CRYPTO 2005, August 2005. 

   [I-D.ietf-tls-ecc-new-mac] 
             Rescorla, E., "TLS Elliptic Curve Cipher Suites with SHA-
             256/384 and AES Galois Counter  Mode", draft-ietf-tls-ecc-
             new-mac-06 (work in progress), April 2008. 

   [I-D.ietf-tls-rsa-aes-gcm] 
             Salowey, J., A. Choudhury, and C. McGrew, "RSA based AES-
             GCM Cipher Suites for TLS", draft-ietf-tls-rsa-aes-gcm-03 
             (work in progress), April 2008. 






 
 
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Author's Addresses 

   Mohamad Badra 
   LIMOS Laboratory - UMR6158, CNRS 
   France 
    
   Email: badra@isima.fr 
    

Full Copyright Statement 

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   this standard.  Please address the information to the IETF at ietf-
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Acknowledgment 

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