KITTEN WG N. Williams Internet-Draft Sun Intended status: Standards Track September 23, 2008 Expires: March 27, 2009 Clarifications and Extensions to the GSS-API for the Use of Channel Bindings draft-ietf-kitten-gssapi-channel-bindings-05.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 March 27, 2009. Copyright Notice Copyright (C) The IETF Trust (2008). Williams Expires March 27, 2009 [Page 1] Internet-Draft GSS-API Channel Bindings September 2008 Abstract This document clarifies and generalizes the Generic Security Services Application Programming Interface (GSS-API) "channel bindings" facility, and imposes requirements on future GSS-API mechanisms and programming language bindings of the GSS-API. Table of Contents 1. Conventions used in this document . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. New Requirements for GSS-API Mechanisms . . . . . . . . . . . 5 4. Generic Structure for GSS-API Channel Bindings . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. Normative References . . . . . . . . . . . . . . . . . . . . . 9 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10 Intellectual Property and Copyright Statements . . . . . . . . . . 11 Williams Expires March 27, 2009 [Page 2] Internet-Draft GSS-API Channel Bindings September 2008 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 March 27, 2009 [Page 3] Internet-Draft GSS-API Channel Bindings September 2008 2. Introduction The base GSS-API v2, update 1 specification [RFC2743] provides a facility for channel binding (see also [RFC5056]), but its treatment was incomplete. The C-bindings of the GSS-API [RFC2744] expanded a little on this facility in what should have been a generic way, but was a C-specific way, and still, the treatment of this facility was incomplete. This document clarifies the GSS-API's channel binding facility and generalizes the parts of it that are specified in the C-bindings document but which should have been generic from the first. Williams Expires March 27, 2009 [Page 4] Internet-Draft GSS-API Channel Bindings September 2008 3. New Requirements for GSS-API Mechanisms Given the publication of RFC5056 we now assert that all new GSS-API mechanisms that support channel binding MUST conform to [RFC5056]. Williams Expires March 27, 2009 [Page 5] Internet-Draft GSS-API Channel Bindings September 2008 4. Generic Structure for GSS-API Channel Bindings The base GSS-API v2, update 1 specification [RFC2743] provides a facility for channel binding. It models channel bindings as an OCTET STRING and leaves it to the GSS-API v2, update 1 C-Bindings specification to specify the structure of the contents of the channel bindings OCTET STRINGs. The C-Bindings specification [RFC2744] then defines, in terms of C, what should have been a generic structure for channel bindings. The Kerberos V GSS mechanism [RFC4121] also defines a method for encoding GSS channel bindings in a way that is independent of the C-Bindings -- otherwise the mechanism's channel binding facility would not be useable with other language bindings. In other words, the structure of GSS channel bindings given in [RFC2744] is actually generic, rather than specific to the C programming language. Here, then, is a generic re-statement of this structure, in pseudo- ASN.1: GSS-CHANNEL-BINDINGS ::= SEQUENCE { initiator-address-type INTEGER, -- See RFC2744 initiator-address OCTET STRING, -- See RFC2744 acceptor-address-type INTEGER, -- See RFC2744 acceptor-address OCTET STRING, -- See RFC2744 application-data OCTET STRING, -- See RFC5056 } The values for the address fields are described in [RFC2744]. New language-specific bindings of the GSS-API SHOULD specify a language-specific formulation of this structure. Where a language binding of the GSS-API models channel bindings as OCTET STRINGs (or the language's equivalent), then the implementation MUST assume that the given bindings correspond only to the application-data field of GSS-CHANNEL-BINDINGS as shown above, rather than some encoding of GSS-CHANNEL-BINDINGS. As mentioned above, [RFC4121] describes an encoding of the above GSS- CHANNEL-BINDINGS structure, and then hashes that encoding. Other GSS-API mechanisms are free to use that encoding. Williams Expires March 27, 2009 [Page 6] Internet-Draft GSS-API Channel Bindings September 2008 5. IANA Considerations There are no IANA considerations in this document. Williams Expires March 27, 2009 [Page 7] Internet-Draft GSS-API Channel Bindings September 2008 6. Security Considerations For general security considerations relating to channel bindings see [RFC5056]. Language bindings that use OCTET STRING (or equivalent) for channel bindings will not support the use of network addresses as channel bindings. This should not cause any security problems, as the use of network addresses as channel bindings is not generally secure. However, it is important that "end-point channel bindings" not be modelled as network addresses, otherwise such channel bindings may not be useable with all language bindings of the GSS-API. Williams Expires March 27, 2009 [Page 8] Internet-Draft GSS-API Channel Bindings September 2008 7. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2743] Linn, J., "Generic Security Service Application Program Interface Version 2, Update 1", RFC 2743, January 2000. [RFC2744] Wray, J., "Generic Security Service API Version 2 : C-bindings", RFC 2744, January 2000. [RFC4121] Zhu, L., Jaganathan, K., and S. Hartman, "The Kerberos Version 5 Generic Security Service Application Program Interface (GSS-API) Mechanism: Version 2", RFC 4121, July 2005. [RFC5056] Williams, N., "On the Use of Channel Bindings to Secure Channels", RFC 5056, November 2007. Williams Expires March 27, 2009 [Page 9] Internet-Draft GSS-API Channel Bindings September 2008 Author's Address Nicolas Williams Sun Microsystems 5300 Riata Trace Ct Austin, TX 78727 US Email: Nicolas.Williams@sun.com Williams Expires March 27, 2009 [Page 10] Internet-Draft GSS-API Channel Bindings September 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). 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. 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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. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Williams Expires March 27, 2009 [Page 11]