IETF PKIX WG Stefan Santesson Internet Draft (3xA Security) Intended Status: Proposed Standard Nick Pope Updates: 3161 (once approved) (Thales) Expires: February 24, 2010 August 23, 2009 Update for ESSCertIDv2 draft-ietf-pkix-rfc3161-update-00.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Abstract This document updates RFC 3161 [RFC3161]. It allows the use of ESSCertIDv2 defined in RFC 5035 [ESSv2] to specify the hash of a signer certificate when the hash is calculated with a function other than SHA 1 [SHA1]. Santesson, et al. Expires February 24, 2010 [Page 1] INTERNET DRAFT RFC 3161 Update August 23, 2009 Table of Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Updates to RFC 3161 . . . . . . . . . . . . . . . . . . . . . . 4 2.1 Changes to section 2.4.1 Request Format . . . . . . . . . . 4 2.2 Changes to Section 2.4.2 Response Format . . . . . . . . . 4 2.2.1 signature of time stamp token . . . . . . . . . . . . 4 2.2.2 verifying the time stamp token . . . . . . . . . . . . 5 3 Security Considerations . . . . . . . . . . . . . . . . . . . . 6 4 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 5 Normative References . . . . . . . . . . . . . . . . . . . . . . 7 Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 8 Santesson, et al. Expires February 24, 2010 [Page 2] INTERNET DRAFT RFC 3161 Update August 23, 2009 1 Introduction The time stamping protocol defined in RFC 3161 [RFC3161] require CMS [RFC3852] signatures on time-stamp tokens to include an identifier of the signer's certificate to be included as a signed attribute according to [ESS]. This identifier only allows SHA 1 to be used as hash algorithm to generate the identifier value. RFC 2634 [ESS] has since then been updated by RFC 5035 [ESSv2] which defines the updated certificate identifier ESSCertIDv2, which allows use of any hash algorithm. The changes to RFC 3161 [RFC3161] defined in this document allows ESSCertIDv2 to be used to include an identifier of the signing certificate as defined in RFC 5035 [ESSv2] 1.1 Terminology 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 RFC 2119 [RFC2119]. Santesson, et al. Expires February 24, 2010 [Page 3] INTERNET DRAFT RFC 3161 Update August 23, 2009 2 Updates to RFC 3161 2.1 Changes to section 2.4.1 Request Format Last paragraph on page 5. Old: If the certReq field is present and set to true, the TSA's public key certificate that is referenced by the ESSCertID identifier inside a SigningCertificate attribute in the response MUST be provided by the TSA in the certificates field from the SignedData structure in that response. That field may also contain other certificates. New: If the certReq field is present and set to true, the TSA's public key certificate that is referenced by the ESSCertID [ESS] field inside a SigningCertificate attribute or by the ESSCertIDv2 [ESSv2] field inside a SigningCertificateV2 attribute in the response MUST be provided by the TSA in the certificates field from the SignedData structure in that response. That field may also contain other certificates. 2.2 Changes to Section 2.4.2 Response Format 2.2.1 signature of time stamp token 5th paragraph on page 8, just before the definition of TSTInfo. Old: The time-stamp token MUST NOT contain any signatures other than the signature of the TSA. The certificate identifier (ESSCertID) of the TSA certificate MUST be included as a signerInfo attribute inside a SigningCertificate attribute. New: The time-stamp token MUST NOT contain any signatures other than the signature of the TSA. The certificate identifier (either ESSCertID [ESS] or ESSCertIDv2 [ESSv2]) of the TSA certificate MUST be included as a signerInfo attribute inside a SigningCertificate attribute. Santesson, et al. Expires February 24, 2010 [Page 4] INTERNET DRAFT RFC 3161 Update August 23, 2009 Note: As mentioned in RFC 5035 [ESSV2], the SigningCertificateV2 attribute MUST be used if any algorithm other than SHA-1 is used and SHOULD NOT be used for SHA-1. 2.2.2 verifying the time stamp token 3rd paragraph on page 11. Old: The purpose of the tsa field is to give a hint in identifying the name of the TSA. If present, it MUST correspond to one of the subject names included in the certificate that is to be used to verify the token. However, the actual identification of the entity that signed the response will always occur through the use of the certificate identifier (ESSCertID Attribute) inside a SigningCertificate attribute which is part of the signerInfo (See Section 5 of [ESS]). New: The purpose of the tsa field is to give a hint in identifying the name of the TSA. If present, it MUST correspond to one of the subject names included in the certificate that is to be used to verify the token. However, the actual identification of the entity that signed the response will always occur through the use of the certificate identifier (ESSCertID inside a SigningCertificate attribute or ESSCertIDv2 inside a SigningCertificateV2 attribute) which is part of the signerInfo (See Section 5 of [ESS] and Section 3 of [ESSv2]). Santesson, et al. Expires February 24, 2010 [Page 5] INTERNET DRAFT RFC 3161 Update August 23, 2009 3 Security Considerations This draft incorporates the security considerations of RFC 5035 [ESSv2] Provided that the PKI used to validate the TSA certificate is not broken or compromised, the identifier used to identify the signer certificate is only used to distinguish between valid non revoked TSA certificates. The chance of colliding identifiers is negligible even if a poor hash algorithm is used. The update provided by this draft is thus motivated by reasons of interoperability and migration to other hash algorithms rather than security. 4 IANA Considerations This draft requires no actions by IANA Santesson, et al. Expires February 24, 2010 [Page 6] INTERNET DRAFT RFC 3161 Update August 23, 2009 5 Normative References [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [ESS] Hoffman, P., "Enhanced Security Services for S/MIME", RFC 2634, June 1999. [ESSv2] Schaad, J., Enhanced Security Services (ESS) Update: Adding CertID Algorithm Agility. RFC 5035. August 2007. [RFC3161] Adams, C., Cain, P., Pinkas, D. and Zuccherato, R. "Time- Stamp Protocol (TSP)". RFC 3161. August 2001. [SHA1] Secure Hash Standard. FIPS Pub 180-1. National Institute of Standards and Technology. 17 April 1995. Author's Addresses Stefan Santesson 3xA Security AB Sweden Email: sts@aaa-sec.com Nick Pope Thales Information Systems Security Long Crendon, Aylesbury United Kingdom Santesson, et al. Expires February 24, 2010 [Page 7] INTERNET DRAFT RFC 3161 Update August 23, 2009 Full Copyright Statement Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. All IETF Documents and the information contained therein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST 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 THEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Santesson, et al. Expires February 24, 2010 [Page 8]