[cabf_validation] CRL Validity Interval Ballot

Tim Hollebeek tim.hollebeek at digicert.com
Fri Oct 29 20:23:52 UTC 2021

Line 1301: “i. once every 367 days; and”


I think that provision needs an “at least” as well.  I don’t think we expect CAs to issue CRLs once every 367 days.




From: Wayne Thayer <wthayer at gmail.com> 
Sent: Monday, October 18, 2021 8:29 PM
To: Ryan Sleevi <sleevi at google.com>
Cc: Dimitris Zacharopoulos (HARICA) <dzacharo at harica.gr>; CABforum3 <validation at cabforum.org>; Tim Hollebeek <tim.hollebeek at digicert.com>
Subject: Re: [cabf_validation] CRL Validity Interval Ballot


Thank you Ryan! I merged in your changes: https://github.com/cabforum/servercert/compare/main...wthayer:ballot-SC52 


On Fri, Oct 15, 2021 at 2:12 PM Ryan Sleevi <sleevi at google.com <mailto:sleevi at google.com> > wrote:

Suggested edits in https://github.com/wthayer/servercert/pull/12/files as PR to your branch


On Fri, Oct 15, 2021 at 4:59 PM Wayne Thayer <wthayer at gmail.com <mailto:wthayer at gmail.com> > wrote:

How does this look?








On Thu, Oct 14, 2021 at 11:50 AM Dimitris Zacharopoulos (HARICA) <dzacharo at harica.gr <mailto:dzacharo at harica.gr> > wrote:

That's my understanding too. If we are to create the "validity interval" definition, we must be clear that it is only applicable to CRLs and OCSP responses and that might be a bit challenging. Also change the term in 4.9.10 "validity interval" instead of "validity period".


On 14/10/2021 7:34 μ.μ., Wayne Thayer wrote:

My conclusion from this discussion is that the ballot should be updated to specify the validity interval of root CRLs and OCSP responses in days instead of months, with 397 days a SHOULD and 398 days a MUST. Ryan and Dimitris, is that correct?


Shall I also create a definition for 'validity interval' and make it applicable to CRLs and OCSP responses?






On Wed, Oct 13, 2021 at 8:08 AM Ryan Sleevi <sleevi at google.com <mailto:sleevi at google.com> > wrote:



On Wed, Oct 13, 2021 at 10:57 AM Dimitris Zacharopoulos (HARICA) <dzacharo at harica.gr <mailto:dzacharo at harica.gr> > wrote:


On 13/10/2021 5:17 μ.μ., Ryan Sleevi wrote:



On Wed, Oct 13, 2021 at 10:05 AM Dimitris Zacharopoulos (HARICA) <dzacharo at harica.gr <mailto:dzacharo at harica.gr> > wrote:

4.9.7 and 4.9.10 have a nextUpdate requirement for Root CRLs and OCSP responses, and this is set for 12 months. Do we want the same level of "accuracy" as the CRL/OCSP responses of Subordinate CAs? If we do not, then we can focus on language about just the CRLs/OCSP responses issued by "online" CAs, as Wayne has already done at the proposed ballot and there is no need to make further changes to the BRs. 

If I understand your position, you believe we should be specific (to the second) only for specific requirements, such as those linked to RFC 5280 (validity of a certificate, validity period of a CRL/OCSP response) and not the other cases (related to request tokens, audit reports, etc). Is that accurate?


Got it. Definite misunderstanding :)


To try to rephrase:

*	Defining a day to be 86,400 seconds (with caveats) is appropriate for Section 1.6.4 if the desire is to make this ballot a broader "date interval" cleanup rather than just the CRL cleanup
*	This convention cannot address the "inclusive" aspect; that will need to remain appropriate for ASN.1 types (certificates, CRLs, OCSP)
*	The term "validity period" refers to certificates, and comes from X.509/RFC 5280. The term "validity interval" is a term we introduced for OCSP, because CRLs and OCSP responses don't necessarily have 'validity periods' (intervals, freshness, etc are all concepts used to refer to them) 

*	Taken together with the previous bullet: This means there still needs to be definitions specific to those, and within the specific sections (long-term, this would be the relevant profiles for certificates, CRLs, and OCSP, rather than the current distributed locations)

*	Procedural controls - request tokens, audit reports, etc - still make sense to define in days

*	However, the choice of period - 90 days vs 93 days, 397 days vs 398 days, 31 days vs 32 days - were intentionally selected to allow CAs to have a fixed calendrical schedule, without risk of violation.
*	For example, if you have a 30 day period, then over a year, you will have shifted 5 to 6 days. You won't be able to, for example, "do something on the first of every month"
*	The "extra day" is to make sure that if you do it at 9am on the 1st of the month prior, you (hopefully unambiguously) have until midnight of the 1st of the current month, without running afoul


Got it. Do you have any guidance or preference for the offline CA CRLs/OCSP responses? Should that continue to be described in months or move into something more specific?


Days was/is the suggestion. Months being 30 days or 31 days has the calendrical drift issue. So 367 days = 1 year/12 months. 


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