Network Working Group P. Hoffman Internet-Draft VPN Consortium Expires: March 28, 2005 September 27, 2004 Algorithms for Internet Key Exchange version 1 (IKEv1) draft-hoffman-ikev1-algorithms-00.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. 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 become aware will be disclosed, in accordance with RFC 3668. 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 March 28, 2005. Copyright Notice Copyright (C) The Internet Society (2004). Abstract The required and suggested algorithms in the original IKEv1 specification does not reflect the current reality of IPsec market. It requires allowing weak security and suggests algorithms that are thinly implemented. This document updates the original specification and is intended for all IKEv1 implementations deployed today. Hoffman Expires March 28, 2005 [Page 1] Internet-Draft Algorithms for IKEv1 September 2004 1. Introduction The original IKEv1 definition, RFC 2409 [RFC2409], has a set of MUST-level and SHOULD-level requirements that do not match the needs of IPsec users. This document updates RFC by changing the algorithm requirements defined there. The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this document, are to be interpreted as described in RFC 2119 [RFC2119]. 2. Old algorithm requirements RFC 2409 has the following MUST-level and SHOULD-level requirements: o DES for encryption MUST be supported o MD5 and SHA-1 for hashing MUST be supported o Diffie-Hellman MODP group 1 (discrete log 768 bits) MUST be supported o TripleDES for encryption SHOULD be supported o Tiger for hashing SHOULD be supported o DSA and RSA for authentication with signatures SHOULD be supported o RSA for authentication with encryption SHOULD be supported o Diffie-Hellman MODP group 2 (discrete log 1024 bits) SHOULD be supported RFC 2409 gives two conflicting requirement levels for Diffie-Hellman MODP groups with elliptic curves. Section 4 of that specification says "IKE implementations ... MAY support ECP and EC2N groups", but Sections 6.3 and 6.4 say that MODP groups 3 and 4 for EC2N groups SHOULD be supported. 3. New algorithm requirements The new requirements for IKEv1 are: o TripleDES for encryption MUST be supported o SHA-1 for hashing MUST be supported o Diffie-Hellman MODP group 2 (discrete log 1024 bits) MUST be supported o RSA for authentication with signatures SHOULD be supported The other algorithms that were listed at MUST-level and SHOULD-level in RFC 2409 are now MAY-level. This includes DES for encryption, MD5 and Tiger for hashing, Diffie-Hellman MODP group 1, Diffie-Hellman MODP groups with elliptic curves, DSA for authentication with signatures, and RSA for authentication with encryption. Some of these are dropped to MAY due to cryptographic weakness, while others Hoffman Expires March 28, 2005 [Page 2] Internet-Draft Algorithms for IKEv1 September 2004 are dropped due to lack of any significant deployment and interoperability. Note that additional algorithms have been developed since the time of RFC 2409 that many people consider SHOULD-level or MUST-level. Most notable among these are discrete log MODP groups with longer key lengths, AES-128 for encryption, and SHA-256 for hashing. They are not included in this document because doing so would cause this document to be an extension to RFC 2409 instead of an update of RFC 2409. 4. Security Considerations This document is all about security. All the algorithms that are either MUST-level or SHOULD-level in the "new algoritm requirements" section of this document are believed to be robust and secure at the time of this writing. 5 Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2409] Harkins, D. and D. Carrel, "The Internet Key Exchange (IKE)", RFC 2409, November 1998. Author's Address Paul Hoffman VPN Consortium 127 Segre Place Santa Cruz, CA 95060 US EMail: paul.hoffman@vpnc.org Hoffman Expires March 28, 2005 [Page 3] Internet-Draft Algorithms for IKEv1 September 2004 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. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. 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 (2004). 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. Hoffman Expires March 28, 2005 [Page 4]