Algorithms for Internet Key Exchange version 1 (IKEv1)
The information below is for an old version of the document that is already published as an RFC.
This is an older version of an Internet-Draft that was ultimately published as RFC 4109.
|Author||Paul E. Hoffman|
|Last updated||2015-10-14 (Latest revision 2004-12-20)|
|RFC stream||Internet Engineering Task Force (IETF)|
|IESG||IESG state||RFC 4109 (Proposed Standard)|
|Responsible AD||Russ Housley|
|Send notices to||(None)|
Network Working Group P. Hoffman Internet-Draft VPN Consortium Expires: June 17, 2005 December 17, 2004 Algorithms for Internet Key Exchange version 1 (IKEv1) draft-hoffman-ikev1-algorithms-03.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 June 17, 2005. Copyright Notice Copyright (C) The Internet Society (2004). Abstract The required and suggested algorithms in the original IKEv1 specification do not reflect the current reality of the IPsec market requirements. The original specification allows weak security and suggests algorithms that are thinly implemented. This document updates RFC 2409, the original specification, and is intended for all IKEv1 implementations deployed today. Hoffman Expires June 17, 2005 [Page 1] Internet-Draft Algorithms for IKEv1 December 2004 1. Introduction The original IKEv1 definition, [RFC2409], has a set of MUST-level and SHOULD-level requirements that do not match the needs of IPsec users. This document updates RFC 2409 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 [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 and HMAC functions MUST be supported o Pre-shared secrets for authentication 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 listed here. Note that some of the requirements are the same as in RFC 2409, while others are changed. o TripleDES for encryption MUST be supported o AES-128 in CBC mode [RFC3602] for encryption SHOULD be supported o SHA-1 for hashing and HMAC functions MUST be supported o Pre-shared secrets for authentication MUST be supported o AES-128 in XCBC mode for PRF functions ([RFC3566] and [RFC3664]) SHOULD be supported o Diffie-Hellman MODP group 2 (discrete log 1024 bits) MUST be supported Hoffman Expires June 17, 2005 [Page 2] Internet-Draft Algorithms for IKEv1 December 2004 o Diffie-Hellman MODP group 14 (discrete log 2048 bits) [RFC3526] SHOULD be supported o RSA for authentication with signatures SHOULD be supported If additional updates are make to IKEv1 in the future, then it is very likely that AES-128 in CBC mode for encryption will become mandatory to implement. 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. DES for encryption, MD5 for hashing, Diffie-Hellman MODP group 1 are dropped to MAY due to cryptographic weakness. Tiger for hashing, Diffie-Hellman MODP groups with elliptic curves, DSA for authentication with signatures, and RSA for authentication with encryption are dropped due to lack of any significant deployment and interoperability. 4. Summary Algorithm RFC 2409 This document ------------------------------------------------------------------ DES for encryption MUST MAY (crypto weakness) TripleDES for encryption SHOULD MUST AES-128 for encryption N/A SHOULD MD5 for hashing and HMAC MUST MAY (crypto weakness) SHA1 for hashing and HMAC MUST MUST Tiger for hashing SHOULD MAY (lack of deployment) AES-XCBC-MAC-96 for PRF N/A SHOULD Pre-shared secrets MUST MUST RSA with signatures SHOULD SHOULD DSA with signatures SHOULD MAY (lack of deployment) RSA with encryption SHOULD MAY (lack of deployment) D-H Group 1 (768) MUST MAY (crypto weakness) D-H Group 2 (1024) SHOULD MUST D-H Group 14 (2048) N/A SHOULD D-H elliptic curves SHOULD MAY (lack of deployment) 5. 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. Hoffman Expires June 17, 2005 [Page 3] Internet-Draft Algorithms for IKEv1 December 2004 6 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. [RFC3526] Kivinen, T. and M. Kojo, "More Modular Exponential (MODP) Diffie-Hellman groups for Internet Key Exchange (IKE)", RFC 3526, May 2003. [RFC3566] Frankel, S. and H. Herbert, "The AES-XCBC-MAC-96 Algorithm and Its Use With IPsec", RFC 3566, September 2003. [RFC3602] Frankel, S., Glenn, R. and S. Kelly, "The AES-CBC Cipher Algorithm and Its Use with IPsec", RFC 3602, September 2003. [RFC3664] Hoffman, P., "The AES-XCBC-PRF-128 Algorithm for the Internet Key Exchange Protocol (IKE)", RFC 3664, January 2004. Author's Address Paul Hoffman VPN Consortium 127 Segre Place Santa Cruz, CA 95060 US EMail: email@example.com Hoffman Expires June 17, 2005 [Page 4] Internet-Draft Algorithms for IKEv1 December 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. 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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 (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 June 17, 2005 [Page 5]