[Servercert-wg] Ballot SC23: Precertificates

Thu Oct 10 12:16:23 MST 2019

Wayne and SCWG folks.  I’ve read the threads on this ballot.  I have two questions for clarification:

  1.  Reading the proposed update to section 4.9.10 of the Baseline Requirements which states ”If the OCSP responder receives an OCSP request but has no record of ever having issued any certificate with the certificate serial number in that request, using any current or previous issuing key for the CA subject, then the responder SHOULD NOT respond with a "good" status. OCSP responders for CAs that are not Technically Constrained in line with Section 7.1.5 MUST NOT respond with a "good" status for such certificates. The CA SHOULD monitor the responder for such requests as part of its security response procedures.”  Are we are stating that a CA must (e.g. shall) be able to provide an OCSP response for a pre-certificate even if there is no corresponding issues certificate?  Is this basically stating that 4.9.10 requires the CA to provide the OCSP service (e.g. ability to provide a response) for pre-certificates even if there is no corresponding issued certificate?  I understand that if there is both the precert and issued cert then OSCP is required.

  1.  Also, current BR section “7.1.2.5 Application of RFC 5280” states “For purposes of clarification, a Precertificate, as described in RFC 6962 – Certificate Transparency, shall not be considered to be a “certificate” subject to the requirements of RFC 5280 - Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile under these Baseline Requirements.”  With the removal of that language from the new BR section 7.1.2.5 does this mean that a precert with no corresponding cert is not defined as a certificate and then does not require to have an OCSP service?

Thanks, Mike

From: Servercert-wg <servercert-wg-bounces at cabforum.org> On Behalf Of Wayne Thayer via Servercert-wg
Sent: Thursday, October 3, 2019 10:30 AM
To: CA/B Forum Server Certificate WG Public Discussion List <servercert-wg at cabforum.org>
Subject: [Servercert-wg] Ballot SC23: Precertificates

Ballot SC23: Precertificates

Purpose of Ballot:

This ballot intends to clarify requirements placed on precertificates in BR section 7.1.2.5.

During a lengthy discussion on the mozilla.dev.security.policy forum [1], it was discovered that BR section 4.9.10 combined with BR section 7.1.2.5 prevents a CA from responding “good” for a precertificate. This is a problem because there is no guarantee that a certificate corresponding to a precertificate has not been issued, resulting in root store policies such as [2] that require CAs to treat the existence of a precertificate as a presumption that a corresponding certificate has been issued and thus that a valid OCSP response is required.

This ballot intends to resolve the problem by reducing the scope of section 7.1.2.5. This section was originally [3] intended only to address duplicate serial numbers that would violate RFC 5280 section 4.1.2.2. In addition, this ballot removes legacy effective dates from BR section 4.9.10.

[1] https://groups.google.com/d/msg/mozilla.dev.security.policy/LC_y8yPDI9Q/NbOmVB77AQAJ<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgroups.google.com%2Fd%2Fmsg%2Fmozilla.dev.security.policy%2FLC_y8yPDI9Q%2FNbOmVB77AQAJ&data=02%7C01%7CMike.reilly%40microsoft.com%7Cda8d31be310d41aca8c308d748274ed5%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637057205980121304&sdata=YsxKzW25uUt76F326BjT4RnCkRr9iDViTUXc0qHiDC8%3D&reserved=0>

[2] https://wiki.mozilla.org/CA/Required_or_Recommended_Practices#Precertificates<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwiki.mozilla.org%2FCA%2FRequired_or_Recommended_Practices%23Precertificates&data=02%7C01%7CMike.reilly%40microsoft.com%7Cda8d31be310d41aca8c308d748274ed5%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637057205980131303&sdata=AEzghuLnZQ98oe1TeDeWb8mnNbt3xlCOHNhcNEfvJPQ%3D&reserved=0>

[3] https://cabforum.org/pipermail/public/2014-January/002694.html<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcabforum.org%2Fpipermail%2Fpublic%2F2014-January%2F002694.html&data=02%7C01%7CMike.reilly%40microsoft.com%7Cda8d31be310d41aca8c308d748274ed5%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637057205980131303&sdata=jcpSkpLXVywgSYZMiCtxDOC2oHzgJqdNJafLq5uQ92E%3D&reserved=0>

The following motion has been proposed by Wayne Thayer of Mozilla and endorsed by Jeremy Rowley of DigiCert and Rob Stradling of Sectigo.

-- MOTION BEGINS --

This ballot modifies the “Baseline Requirements for the Issuance and Management of Publicly-Trusted Certificates” as follows, based on Version 1.6.6:

REPLACE section 7.1.2.5 of the Baseline Requirements in its entirety with:

7.1.2.5 Application of RFC 5280

For purposes of clarification, any Precertificate MAY have the same serial number as exactly one certificate that is not a Precertificate, provided that the two are related as described in RFC 6962 - Certificate Transparency. This is a modification of the uniqueness requirements of RFC 5280  - Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile section 4.1.2.2 under these Baseline Requirements.

REPLACE section 4.9.10 of the Baseline Requirements in its entirety with:

4.9.10 On-line Revocation Checking Requirements

The CA SHALL support an OCSP capability using the GET method for Certificates issued in accordance with these Requirements.

For the status of Subscriber Certificates:

The CA SHALL update information provided via an Online Certificate Status Protocol at least every four days. OCSP responses from this service MUST have a maximum expiration time of ten days.

For the status of Subordinate CA Certificates:

The CA SHALL update information provided via an Online Certificate Status Protocol at least (i) every twelve months and (ii) within 24 hours after revoking a Subordinate CA Certificate.

If the OCSP responder receives an OCSP request but has no record of ever having issued any certificate with the certificate serial number in that request, using any current or previous issuing key for the CA subject, then the responder SHOULD NOT respond with a "good" status. OCSP responders for CAs that are not Technically Constrained in line with Section 7.1.5 MUST NOT respond with a "good" status for such certificates. The CA SHOULD monitor the responder for such requests as part of its security response procedures.

-- MOTION ENDS --

*** WARNING ***: USE AT YOUR OWN RISK.  THE REDLINE BELOW IS NOT THE OFFICIAL VERSION OF THE CHANGES (CABF Bylaws, Section 2.4(1)):

A comparison of the changes can be found at: https://github.com/wthayer/documents/commit/f0b7c0a27fe51e73d5ed5d8d453024c51713ed70<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fwthayer%2Fdocuments%2Fcommit%2Ff0b7c0a27fe51e73d5ed5d8d453024c51713ed70&data=02%7C01%7CMike.reilly%40microsoft.com%7Cda8d31be310d41aca8c308d748274ed5%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637057205980141295&sdata=mX6jXApg2Ueh1i9a14RjSAa5KMv0e%2Fcuf7zhPTFBcMQ%3D&reserved=0>

The procedure for approval of this ballot is as follows:

Discussion (7+ days)

Start Time: 3-October 2019 18:00 UTC

End Time: No earlier than 10-October 2019 18:00 UTC

Vote for approval (7 days)

Start Time: TBD

End Time: TBD
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