TLS Working Group U. Blumenthal Internet Draft P. Goel Expires: April 2007 Intel Corporation October 3, 2006 Pre-Shared Key Cipher Suites with NULL Encryption for Transport Layer Security (TLS) draft-ietf-tls-psk-null-02.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on April 3, 2007. 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. Blumenthal & Goel Expires April 3, 2007 [Page 1] Internet-Draft PSK NULL-encryption Cipher Suites for TLS October 2006 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_PSK, RSA_PSK) 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: Blumenthal & Goel Expires April 3, 2007 [Page 2] Internet-Draft PSK NULL-encryption Cipher Suites for TLS October 2006 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 sensitive information (such as passwords) over connection protected with one of the cipher suites defined in this document. 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]. Blumenthal & Goel Expires April 3, 2007 [Page 3] Internet-Draft PSK NULL-encryption Cipher Suites for TLS October 2006 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 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has Blumenthal & Goel Expires April 3, 2007 [Page 4] Internet-Draft PSK NULL-encryption Cipher Suites for TLS October 2006 made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Blumenthal & Goel Expires April 3, 2007 [Page 5]