[cabfpub] Ballot - expiration of SHA1 certificates

Rick Andrews Rick_Andrews at symantec.com
Fri Sep 5 23:16:14 UTC 2014

Tom, I think it would help to clarify that the SHA-1 deprecation policy doesn't apply to OCSP responses. Earlier discussion in this Forum seemed to exhibit consensus around the continued acceptability of the use of SHA-1 where hash algorithms are called for (in the issuer NameHash and issuer KeyHash, for example). Even though the BRs say (Section 13.2.5) that OCSP responses must conform to RFC 2560 and/or RFC 5019, and those explicitly call for SHA-1, I'd like to see an affirmation (probably in Section 13.2.5) that SHA-1 is still allowed in this one case.


From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org] On Behalf Of Tom Albertson
Sent: Friday, September 05, 2014 3:47 PM
To: public at cabforum.org
Subject: [cabfpub] FW: Ballot - expiration of SHA1 certificates

Hi there,

I have produced a ballot for discussion, which aligns the Baseline Requirements (v1.1.9)  with the planned deprecation of SHA-1.   This ballot uses the dates in the Microsoft SHA-1 deprecation policy<http://blogs.technet.com/b/pki/archive/2013/11/12/sha1-deprecation-policy.aspx> as a reference, and right now only addresses SSL certs.  I think we can offer similar language for code signing certs and possibly other BRs once we have hashed this out for SSL.

New text appears as red underlined.   A small amount of text in Appendix A is proposed for deletion (black strikethrough)  The amendments relate mainly to Section 9.4 Validity Period, with minor conforming changes to Appendix A.

Special thanks to Ben and Gerv and others, who already struggled through this issue in March 2014, that ballot discussion was most instructive.  I have made no efforts to collaborate with other Forum members on this issue except to go back and forth with Kelvin and Aaron here at Microsoft on the best text to offer to represent the Microsoft policy.

Your comments and questions are appreciated, and ultimately we could use an endorser or two of the ballot measure.


Ballot NNN -expirations of SHA1 certificates (FINAL VERSION)

9.4 Validity Period

9.4.1 Subscriber Certificates
Subscriber Certificates issued after the Effective Date MUST have a Validity Period no greater than 60 months.

Except as provided for below, Subscriber Certificates issued after 1 April 2015 MUST have a Validity Period no
greater than 39 months.

Effective 1 November 2014, CAs MUST NOT issue Subscriber Certificates utilizing the SHA-1 algorithm with an Expiry Date greater than 1 January 2017.

Except as provided for below, effective 1 January 2016, CAs MUST NOT issue Subscriber Certificates that utilize the SHA-1 algorithm.

Effective 1 April 2015, CAs MAY continue to issue Subscriber Certificates with a Validity Period greater than 39
months but not greater than 60 months provided that the CA documents that the Certificate is for a system or
software that:
(a) was in use prior to the Effective Date;
(b) is currently in use by either the Applicant or a substantial number of Relying Parties;
(c) fails to operate if the Validity Period is shorter than 60 months;
(d) does not contain known security risks to Relying Parties; and
(e) is difficult to patch or replace without substantial economic outlay.

9.4.2 Root CA Certificates

The SHA-1 deprecation policy and Validity Dates DO NOT apply to Root CA certificates.  CAs MAY continue to use their existing SHA-1 Root Certificates.  CAs MUST use SHA-2 or successor hash algorithms to sign any Subscriber certificates, Subordinate CA certificates, and CRLs effective 1 January 2016.

9.4.3 Subordinate CA Certificates

Effective 1 January 2016, CAs MUST NOT issue Subordinate CA Certificates that utilize the SHA-1 algorithm.  CAs MUST NOT issue SHA-2 Subscriber certificates under SHA-1 Subordinate CA Certificates.

Appendix A - Cryptographic Algorithm and Key Requirements (Normative)

Add this note under Table 2, Subordinate CA certificates:

* SHA-1 MAY be used with RSA keys in accordance with the criteria defined in Section 9.4.3.

And amend this note at the end of the 3 tables.

* SHA-1 MAY be used with RSA keys in accordance with the criteria defined in Section 9.4.1  until SHA-256 is supported widely by browsers used by a substantial
portion of relying-parties worldwide.

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