TLS Working Group                                         U. Blumenthal 
Internet Draft                                                  P. Goel 
Expires: March 2007                                   Intel Corporation 
                                                     September 27, 2006 
                                    
 
                                      
          Pre-Shared Key Cipher Suites with NULL Encryption for 
                      Transport Layer Security (TLS) 


                      draft-ietf-tls-psk-null-01.txt 


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Abstract 

   This document specifies authentication-only cipher suites for the 
   Pre-Shared Key based Transport Layer Security (TLS) protocol to 
   support null encryption. These cipher suites are useful for countries 
   and places with cryptography-related restrictions.  


 
 
 
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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]. 

Table of Contents 

    
   1. Introduction...................................................2 
   2. Cipher Usage...................................................2 
   3. Security Considerations........................................3 
   4. IANA Considerations............................................3 
   5. Acknowledgments................................................3 
   6. References.....................................................4 
      6.1. Normative References......................................4 
   Author's Addresses................................................4 
   Intellectual Property Statement...................................4 
   Disclaimer of Validity............................................5 
   Copyright Statement...............................................5 
   Acknowledgment....................................................5 
    
1. Introduction 

   The RFC for Pre-Shared Key based TLS [TLS-PSK] specifies cipher 
   suites for supporting TLS using pre-shared symmetric keys. However 
   all the cipher suites defined in [TLS-PSK] require encryption. There 
   is a need for cipher suites that support no encryption. This is 
   required for implementations to meet import restrictions in some 
   countries. Even though no encryption is used, these cipher suites 
   support authentication of the client and server to each other, and 
   message integrity. This document augments [TLS-PSK] by adding three 
   more cipher suites (PSK, DHE, RSA) with authentication and integrity 
   only - no encryption. 

    

2. Cipher Usage 

   The new cipher suites proposed here is very similar to cipher suites 
   defined in [TLS-PSK], except that they define null encryption. 

   The cipher suites defined here use the following options for key 
   exchange and hash part of the protocol: 

 
 
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   CipherSuite                     Key Exchange   Cipher      Hash 

   TLS_PSK_WITH_NULL_SHA           PSK            NULL        SHA 
   TLS_DHE_PSK_WITH_NULL_SHA       DHE_PSK        NULL        SHA 
   TLS_RSA_PSK_WITH_NULL_SHA       RSA_PSK        NULL        SHA 
    
   For the meaning of the terms PSK please refer to section 1 in [TLS-
   PSK]. For the meaning of the terms DHE and RSA please refer to 
   section 7.4.2 in [TLS]. 

3. Security Considerations 

   As with all schemes involving shared keys, special care should be 
   taken to protect the shared values and to limit their exposure over 
   time. As this document augments [TLS-PSK], everything stated in its 
   Security Consideration section applies here. In addition, as cipher 
   suites defined here do not support confidentiality - care should be 
   taken not to send confidential information (such as passwords) over 
   TLS-PSK connection with no encryption. 

4. IANA Considerations 

   This document defines three new cipher suites, whose values are to be 
   assigned from the TLS Cipher Suite registry defined in [TLS]. 

   CipherSuite   TLS_PSK_WITH_NULL_SHA      = { 0x00, 0xTBD1 }; 
   CipherSuite   TLS_DHE_PSK_WITH_NULL_SHA  = { 0x00, 0xTBD2 }; 
   CipherSuite   TLS_RSA_PSK_WITH_NULL_SHA  = { 0x00, 0xTBD3 }; 
    
5. Acknowledgments 

   The cipher suites defined in this document are an augmentation to and 
   based on [TLS-PSK]. 






 
 
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6. References 

6.1. Normative References 

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

   [TLS]     Dierks, T. and Rescorla, E., "The TLS Protocol Version 
             1.1", RFC 4346, April 2006. 

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

    

Author's Addresses 

   Uri Blumenthal 
   Intel Corporation 
   1515 State Route 10,  
   PY2-1 10-4 
   Parsippany, NJ 07054 
   USA 
       
   Email: Uri.Blumenthal@intel.com 
    

   Purushottam Goel 
   Intel Corporation 
   2111 N.E. 25 Ave. 
   JF3-414 
   Hillsboro, OR 97124 
   USA 
       
   Email: Purushottam.Goel@intel.com 
    

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Acknowledgment 

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   Internet Society. 






 
 
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