[Servercert-wg] [EXTERNAL] Ballot SC23: Precertificates

[Bruce Morton]

Hi Wayne,

This ballot may impact how CAs are providing OCSP responses precertificates; however, there is no future effectivity date provided. To allow the CAs to be compliant, I would request that we have a effectivity date which is 6 months after the IPR review period is completed.

Thanks, Bruce.

From: Servercert-wg <servercert-wg-bounces at cabforum.org> On Behalf Of Wayne Thayer via Servercert-wg
Sent: Thursday, October 3, 2019 1:30 PM
To: CA/B Forum Server Certificate WG Public Discussion List <servercert-wg at cabforum.org>
Subject: [EXTERNAL][Servercert-wg] Ballot SC23: Precertificates

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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

[2] https://wiki.mozilla.org/CA/Required_or_Recommended_Practices#Precertificates

[3] https://cabforum.org/pipermail/public/2014-January/002694.html


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


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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