MSEC Working Group Seokung Yoon Internet Draft Joongman Kim Expires: July 6, 2008 Yoojae Won Korea Information Security Agency November 6, 2007 MIKEY Capability Discovery draft-seokung-msec-mikey-capability-discovery-00.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 June 25, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document describes a negotiation procedure to reduce the number of roundtrip defined in RFC 3830 for seeking a common set of parameters between user agents. Yoon, et al. Expires July 6, 2008 [Page 1] Internet-Draft MIKEY Capability Discovery November 6, 2007 Table of Contents 1. Introduction................................................3 2. Terminology.................................................3 3. MIKEY Capability Negotiation Solution........................3 3.1. Pre-shared key.........................................4 3.2. Public-key encryption..................................4 3.3. Diffie-Hellman key exchange.............................5 4. Security Considerations......................................5 5. IANA Considerations.........................................5 6. References..................................................6 6.1. Normative References...................................6 Author's Addresses.............................................7 Intellectual Property Statement.................................8 Disclaimer of Validity.........................................8 Yoon, et al. Expires July 1, 2008 [Page 2] Internet-Draft MIKEY Capability Discovery November 6, 2007 1. Introduction The Multimedia Internet Keying (MIKEY)[2] creates messages to exchange keys and related security parameters and specifies negotiation procedure to exchange messages. The Negotiation procedure defined in RFC 3830 is that the initiator indicates the security policy to be used. If the responder does not support it, the responder can together with an error message, send back its own capabilities to let the Initiator choose a common set of parameters. But, this procedure is not appropriate for real-time Voice over IP (VoIP) communications in that the number of roundtrip for seeking a common algorithm increases if initiator and responder have many encryption algorithms. This document describes a negotiation procedure to reduce the number of roundtrip defined in RFC 3830 for seeking a common set of parameters between user agents. The parameters defined in this document are exactly same as defined in RFC 3830 [1]. 2. Terminology 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 RFC-2119 [1]. 3. MIKEY Capability Negotiation Solution The Initiator sends its own capabilities to let the Responder choose a common set of parameters. This is done by including one or more security policy payloads. If the Responder does support the set of parameters suggested by the Initiator, the Responder message SHOULD include the supported parameters using security payload. If the Responder does not support it, the Responder can together with an error message, send back its own capabilities (negotiation). This is done to reduce the number of roundtrip. (one roundtrip is enough) Yoon, et al. Expires July 1, 2008 [Page 3] Internet-Draft MIKEY Capability Discovery November 6, 2007 If the Responder is not willing/capable of providing security or the parties simply cannot agree, it is up to the parties' polices how to behave, for example, accepting or rejecting an insecure communication. The Responder message is formed as: 3.1. Pre-shared key Initiator Responder I_Message = HDR, T, RAND, [ IDi ], [ IDr ], {SP}, KEMAC ---> [<---] R_MESSAGE = HDR, T, [ IDr ], {SP}, V 3.2. Public-key encryption Initiator Responder I_Message = HDR, T, RAND, [ IDi|CERTi ], [ IDr ], {SP}, KEMAC, [ CHASH ], PKE, SIGNi ---> [<---] R_MESSAGE = HDR, T, [ IDr ], {SP}, V Yoon, et al. Expires July 1, 2008 [Page 4] Internet-Draft MIKEY Capability Discovery November 6, 2007 3.3. Diffie-Hellman key exchange Initiator Responder I_Message = HDR, T, RAND, [ IDi|CERTi ], [ IDr ], {SP}, DHi, SIGNi ---> [<---] R_MESSAGE = HDR, T, [ IDr|CERTr ], IDi, {SP}, DHr, DHi, SIGHr 4. Security Considerations 5. IANA Considerations Yoon, et al. Expires July 1, 2008 [Page 5] Internet-Draft MIKEY Capability Discovery November 6, 2007 6. References 6.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Arkko, J., "MIKEY: Multimedia Internet KEYing", RFC 3830, August, 2004. Yoon, et al. Expires July 1, 2008 [Page 6] Internet-Draft MIKEY Capability Discovery November 6, 2007 Author's Addresses Seokung Yoon Korea Information Security Agency 78, Karak-dong, Songpa-Gu Seoul 138-160 KOREA Phone: +82-2-405-5361 Email: seokung@kisa.or.kr Joongman Kim Korea Information Security Agency 78, Karak-dong, Songpa-Gu Seoul 138-160 KOREA Phone: +82-2-405-5314 Email: seopo@kisa.or.kr Yoojae Won Korea Information Security Agency 78, Karak-dong, Songpa-Gu Seoul 138-160 KOREA Phone: +82-2-405-5360 Email: yjwon@kisa.or.kr Yoon, et al. Expires July 1, 2008 [Page 7] Internet-Draft MIKEY Capability Discovery November 6, 2007 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 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. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. 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Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Yoon, et al. Expires July 1, 2008 [Page 8]