NETWORK WORKING GROUP N. Williams Internet-Draft Sun Expires: December 30, 2004 July 2004 A PRF for the Kerberos V GSS-API Mechanism draft-ietf-kitten-krb5-gssapi-prf-00.txt Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I 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 December 30, 2004. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This document defines the Pseudo-Random Function (PRF) for the Kerberos V GSS-API mechanism, based on the PRF defined for the Kerberos V cryptographic framework, for keying application protocols given an established Kerberos V GSS-API security context. Williams Expires December 30, 2004 [Page 1] Internet-Draft A PRF for the Kerberos V Mech July 2004 Table of Contents 1. Conventions used in this document . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 4. Normative . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 Intellectual Property and Copyright Statements . . . . . . . . . 6 Williams Expires December 30, 2004 [Page 2] Internet-Draft A PRF for the Kerberos V Mech July 2004 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 December 30, 2004 [Page 3] Internet-Draft A PRF for the Kerberos V Mech July 2004 2. Introduction The GSS-API PRF [GSS-PRF] function for the Kerberos V mechanism shall be the output of a PRF+ function based on the enctype's PRF function keyed with the negotiated session key of the security context (e.g., the acceptor's subkey) and key usage X (TBD). The PRF+ function is a simple counter-based extension of the enctype's prf using an 16-bit network byte order unsigned binary counter: PRF+(k, input) = random-to-key( k-truncate( prf(k, 0 || input) || prf(k, 1 || input), .. prf(k, n || input))). The maximum output length for this PRF+ then is 65536 times the output length of the Kerberos V cryptographic framework PRF for the enctype of the input key. If the desired_output_len input parameter exceeds the maximum output of this function then the maximum will be output instead. Williams Expires December 30, 2004 [Page 4] Internet-Draft A PRF for the Kerberos V Mech July 2004 3. Security Considerations Kerberos V enctypes' PRF functions use a key derived from contexts' session keys and should preserve the forward security properties of the mechanisms' key exchanges. See also [GSS-PRF] for generic security considerations of GSS_Pseudo_random(). 4 Normative [GSS-PRF] Williams, N., "A PRF API extension for the GSS-API". [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. Author's Address Nicolas Williams Sun Microsystems 5300 Riata Trace Ct Austin, TX 78727 US EMail: Nicolas.Williams@sun.com Williams Expires December 30, 2004 [Page 5] Internet-Draft A PRF for the Kerberos V Mech July 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. Williams Expires December 30, 2004 [Page 6]