NETWORK WORKING GROUP N. Williams Internet-Draft Sun Expires: August 26, 2006 February 22, 2006 Better-Than-Nothing-Security: An Unauthenticated Mode of IPsec draft-ietf-btns-core-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 August 26, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This document specifies how to use the Internet Key Exchange (IKE) protocols, such as IKEv1 and IKEv2, to setup "unauthenticated" security associations (SAs) for use with the IPsec Encapsulating Security Payload (ESP) and the IPsec Authentication Header (AH). No IKE extensions are needed, but Peer Authorization Database (PAD) and Security Policy Database (SPD) extensions are specified. Unauthenticated IPsec is herein referred to by its popular acronym, "BTNS" (Better Than Nothing Security). Williams Expires August 26, 2006 [Page 1] Internet-Draft BTNS IPsec February 2006 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . . . 3 2. BTNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Security Considerations . . . . . . . . . . . . . . . . . . . 5 4. Normative . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . 7 Williams Expires August 26, 2006 [Page 2] Internet-Draft BTNS IPsec February 2006 1. Introduction Here we describe how to establish unauthenticated IPsec SAs using IKEv1 [RFC2408] [RFC2409] or IKEv2 [RFC4306] and unauthenticated public keys. No new on-the-wire protocol elements are added to IKE or IKEv2. The [RFC4301] processing model is assumed. This document does not define an opportunistic BTNS mode of IPsec whereby nodes may fallback on unprotected IP when their peers do not support IKE or IKEv2, nor does it describe "leap-of-faith" modes, or "connection latching." See [I-D.ietf-btns-prob-and-applic] for the applicability and uses of BTNS. 1.1. 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]. Williams Expires August 26, 2006 [Page 3] Internet-Draft BTNS IPsec February 2006 2. BTNS The IPsec processing model, IKE and IKEv2 are hereby modified as follows: o A new ID type is added, 'PUBLICKEY'; IDs of this type have public keys as values. This ID type is not used on the wire. o A BTNS-specific PAD entry. This entry is intended to be the last entry in the PAD when BTNS is enabled. A peer that matches no other PAD entries is to be "authenticated" by verifying that the signature in its AUTH (or SIG) payload in the IKEv2 (or v1) exchange with the public key from the peer's CERT payload. The peer's ID MUST then be coerced to be of 'PUBLICKEY' type with the peer's public key as its value. o A new flag for SPD entries: 'BTNS_OK'. Traffic to/from peers that match the BTNS PAD entry will only match SPD entries that have the BTNS_OK flag set. The SPD may be searched done by address or by ID (of typ PUBLICKEY, of course, for BTNS peers), as per the IPsec processing model [RFC4301]; searching by ID in this case requires creation of SPD entries that are bound to public key values (this could be used to build "leap-of-faith" behaviour, for example). Nodes MUST reject IKE_SA proposals from peers that match non-BTNS PAD entries but fail to authenticated properly. Nodes wishing to be treated as BTNS nodes by their peers SHOULD use CERT payloads generated for the purpose (i.e., ephemeral, non-pre- shared self-signed certificates or bare RSA public keys). Note that nodes may unwittingly match peers' BTNS PAD entries and be authenticated as BTNS nodes, as long as they do not match any non- BTNS PAD entries. Williams Expires August 26, 2006 [Page 4] Internet-Draft BTNS IPsec February 2006 3. Security Considerations Unauthenticated security association negotiation is subject to MITM attacks and should be used with care. Where security infrastructures are lacking this may indeed be better than nothing. Use with applications that bind authentication at higher network layers to secure channels at lower layers may provide one secure way to use unauthenticated IPsec, but this is not specified herein. [...] 4. Normative [I-D.ietf-btns-prob-and-applic] Touch, J., "Problem and Applicability Statement for Better Than Nothing Security (BTNS)", draft-ietf-btns-prob-and-applic-00 (work in progress), July 2005. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2408] Maughan, D., Schneider, M., and M. Schertler, "Internet Security Association and Key Management Protocol (ISAKMP)", RFC 2408, November 1998. [RFC2409] Harkins, D. and D. Carrel, "The Internet Key Exchange (IKE)", RFC 2409, November 1998. [RFC4301] Kent, S. and K. Seo, "Security Architecture for the Internet Protocol", RFC 4301, December 2005. [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", RFC 4306, December 2005. Williams Expires August 26, 2006 [Page 5] Internet-Draft BTNS IPsec February 2006 Author's Address Nicolas Williams Sun Microsystems 5300 Riata Trace Ct Austin, TX 78727 US Email: Nicolas.Williams@sun.com Williams Expires August 26, 2006 [Page 6] Internet-Draft BTNS IPsec February 2006 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 (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. Williams Expires August 26, 2006 [Page 7]