NETWORK WORKING GROUP L. Zhu Internet-Draft K. Jaganathan Expires:
February 8,May 21, 2005 Microsoft Corporation N. Williams Sun Microsystems August 10,November 20, 2004 OCSP Support for PKINIT draft-ietf-krb-wg-ocsp-for-pkinit-01draft-ietf-krb-wg-ocsp-for-pkinit-02 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 February 8,May 21, 2005. Copyright Notice Copyright (C) The Internet Society (2004). Abstract This document defines a mechanism to enable in-band transmission of OCSP responses. These responses are used to verify the validity of the certificates used in PKINIT - the Kerberos Version 5 extension that provides for the use of public key cryptography. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .3 2. Conventions Used in This Document . . . . . . . . . . . . . .4 3. Message Definition . . . . . . . . . . . . . . . . . . . . . .5 4. Security Considerations . . . . . . . . . . . . . . . . . . .6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . .7 6. ReferencesAcknowledgement . . . . . . . . . . . . . . . . . . . . . . 8 7. References . . . . 7. . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 78 Intellectual Property and Copyright Statements . . . . . . . . 910 1. Introduction Online Certificate Status Protocol (OCSP) [RFC2560] enables applications to obtain timely information regarding the revocation status of a certificate. Because OCSP responses are well-bounded and small in size, constrained clients may wish to use OCSP to check the validity of KDC certificates in order to avoid transmission of large Certificate Revocation Lists (CRLs) and therefore save bandwidth on constrained networks.networks [OCSP-PROFILE]. This document defines a pre-authentication type [CLARIFICATIONS], where the client and the KDC MAY piggyback OCSP responses for certificates used in authentication exchanges, as defined in [PKINIT]. By using this OPTIONAL extension, PKINIT clients and the KDC can maximize the reuse of cached OCSP responses. 2. 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]. 3. Message Definition A pre-authentication type identifier is defined for this mechanism: PA-PK-OCSP-RESPONSE 16 The corresponding pre-authentication field contains OCSP data as follows: PA-PK-OCSP-DATA ::= SEQUENCE OF OcspResponse OcspResponse ::= OCTET STRING -- contains a complete OCSP response, -- defined in [RFC2560] The client MAY send OCSP responses for certificates used in PA-PK-AS-REQ [PKINIT] via a PA-PK-OCSP-RESPONSE. The KDC that receives a PA-PK-OCSP-RESPONSE the SHOULD send a PA-PK-OCSP-RESPONSE in response. The client can request a PA-PK-OCSP-RESPONSE by using an empty sequence in its request. The KDC MAY send a PA-PK-OCSP-RESPONSE when it does not receive a PA-PK-OCSP-RESPONSE from the client. The PA-PK-OCSP-RESPONSE sent by the KDC contains OCSP responses for certificates used in PA-PK-AS-REP [PKINIT]. Note the lack of integrity protection for the empty or missing OCSP response; lack of an expected OCSP response from the KDC for the KDC's certificates SHOULD be treated as an error by the client, unless it is configured otherwise. When using OCSP, the response is signed by the OCSP server, which is trusted by the receiver. Depending on local policy, further verification of the validity of the OCSP servers MAY need to be done. The client and the KDC SHOULD ignore invalid OCSP responses received via this mechanism, and they MAY implement CRL processing logic as a fall-back position, if the OCSP responses received via this mechanism alone are not sufficient for the verification of certificate validity. The client and/or the KDC MAY ignore a valid OCSP response and perform their own revocation status verification independently. 4. Security Considerations The pre-authentication data in this document do not actually authenticate any principals, and MUST be used in conjunction with PKINIT. There is a downgrade attack against clients which want OCSP responses from the KDC for the KDC's certificates. The clients, however, can treat the absence of valid OCSP responses as an error, based on their local configuration. 5. IANA Considerations This document defines a new pre-authentication type for use with PKINIT to encode OCSP responses. The official value for this padata identifier need to be acquired from IANA. 66. Acknowledgements This document was based on conversations among the authors, Jeffrey Altman, Sam Hartman, Martin Rex and other members of the Kerberos working group. 7 References [CLARIFICATIONS] Neuman, B., Yu, Y., Hartman, S. and K. Raeburn, "The Kerberos Network Authentication Service (V5)", draft-ietf-krb-wg-kerberos-clarifications, Work in progress. [OCSP-PROFILE] Deacon, A. and R. Hurst, "Lightweight OCSP Profile for High Volume Environments", draft-ietf-pkix-lightweight-ocsp-profile, Work in progress. [PKINIT] Tung, B., Neuman, B. and B. Neuman,S. Medvinsky, "Public Key Cryptography for Initial Authentication in Kerberos", draft-ietf-cat-kerberos-pk-init, Work in progress. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2560] Myers, M., Ankney, R., Malpani, A., Galperin, S. and C. Adams, "X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSP", RFC 2560, June 1999. Authors' Addresses Larry Zhu Microsoft Corporation One Microsoft Way Redmond, WA 98052 US EMail: firstname.lastname@example.org Karthik Jaganathan Microsoft Corporation One Microsoft Way Redmond, WA 98052 US EMail: email@example.com Nicolas Williams Sun Microsystems 5300 Riata Trace Ct Austin, TX 78727 US EMail: Nicolas.Williams@sun.com 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 firstname.lastname@example.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 This document was based on conversations amongFunding for the authors, Jeffrey Altman, Sam Hartman, Martin Rex, and other members ofRFC Editor function is currently provided by the Kerberos working group.Internet Society.