[Servercert-wg] Compromised/Weak Keys Ballot Proposal

Sun Feb 25 07:05:07 UTC 2024

Thanks Wayne, 

>- The Debian vulnerability is more than 15 years old. If an Applicant submits a Debian weak key at this point, they almost certainly have bigger security issues. 

This is the bit I have problems with. Just because the applicant (probably) has bigger security issues, doesn’t mean we should be putting relying parties at even further risk. If that’s our measure stick, we might as wel allow MD5 again because only insecure systems would generate it.

Just this year I’ve seen at least one applicant trying to submit a debian weak key for order (which obviously got blocked). 

I really like what was done with this ballot, except for this bit. I’d even be alright with removing the debian weak key check requirement itself. But calling it out explicitly as an excempt, I feel is a step too much. 

Regards,

Martijn 

From: Wayne Thayer <wthayer at gmail.com>
Date: Friday, 23 February 2024 at 17:21
To: Martijn Katerbarg <martijn.katerbarg at sectigo.com>
Cc: CA/B Forum Server Certificate WG Public Discussion List <servercert-wg at cabforum.org>
Subject: Re: [Servercert-wg] Compromised/Weak Keys Ballot Proposal 

CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. 

Martijn, 

I would summarize the reasoning for removing the Debian requirements as follows: 

- CAs would prefer the greater clarity that would be provided by the weak keys ballot that failed last year. 

- However, some CAs were of the opinion that the prior ballot imposed more explicit requirements for Debian weak key checking rather than just clarifying existing requirements. The "new" requirements were viewed as burdensome. 

- The Debian vulnerability is more than 15 years old. If an Applicant submits a Debian weak key at this point, they almost certainly have bigger security issues. 

- So the cost of these requirements outweighs the benefits at this point in time. 

I included a few links to the discussion during the prior balot's voting period, and there was also discussion at the last SCWG teleconference that should be captured in the minutes. 

Thanks, 

Wayne 

On Fri, Feb 23, 2024 at 2:19 AM Martijn Katerbarg <martijn.katerbarg at sectigo.com <mailto:martijn.katerbarg at sectigo.com>> wrote: 

Wayne, 

Apologies if I’ve missed something in discussions, but why exactly are we removing the Debian Weak Keys language, and even explicitly mentioned that CAs do not need to check for them (anymore)? 

Regards,

Martijn 

From: Servercert-wg <servercert-wg-bounces at cabforum.org <_blank>> on behalf of Wayne Thayer via Servercert-wg <servercert-wg at cabforum.org <_blank>>
Date: Thursday, 22 February 2024 at 20:01
To: CA/B Forum Server Certificate WG Public Discussion List <servercert-wg at cabforum.org <_blank>>
Subject: Re: [Servercert-wg] Compromised/Weak Keys Ballot Proposal 

CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. 

I am seeking a second endorser for this proposal. Below is a draft of the ballot language. 

Thanks, 

Wayne 

================================ 

**Ballot SC-XX: Compromised / Weak Keys**

This ballot updates BR section 6.1.1.3 to address two issues:

First, the requirements placed on CAs to reject a certificate request if they have been “made aware” that the key pair is compromised is vague and open-ended in regard to how CAs may be “made aware”. This ballot specifies that CAs be “made aware” via their problem reporting mechanism.

Second, this ballot reintroduces the language from [failed] ballot SC-59: Weak Key Guidance. However, based on feedback received during the discussion and voting period for that ballot, Debian weak key checks are now explicitly out of scope.

This ballot is proposed by Wayne Thayer (Fastly) and endorsed by Brittany Randall (GoDaddy) and <someone else( )>. You can view and comment on the github pull request representing this ballot here: https://github.com/wthayer/servercert/pull/1/files <_blank> 

The preceding discussions can be seen here:

* This ballot: https://lists.cabforum.org/pipermail/servercert-wg/2024-February/004195.html <_blank> 
* The prior weak keys ballot: https://lists.cabforum.org/pipermail/servercert-wg/2023-July/003820.html <_blank> and https://lists.cabforum.org/pipermail/servercert-wg/2023-July/003857.html <_blank>
* The “made aware” language in 6.1.1.3 <_blank>: https://lists.cabforum.org/pipermail/servercert-wg/2023-July/003902.html <_blank>

--- Motion Begins ---

This ballot modifies the "Baseline Requirements for the Issuance and Management of Publicly-Trusted Certificates" ("Baseline Requirements") based on Version 2.X.X

MODIFY the Baseline Requirements as specified in the following redline: <Immutable redline link>

--- Motion Ends ---

Discussion (at least 7 days):

- Start: TBD UTC
- End: TBD UTC

Vote for approval (7 days):

- Start: TBD UTC
- End: TBD UTC 

On Mon, Feb 12, 2024 at 6:12 PM Wayne Thayer via Servercert-wg <servercert-wg at cabforum.org <_blank>> wrote: 

Thank you fo the feedback Aaron. I agree with both points you made in the PR and have updated it to reflect your suggestions. 

- Wayne 

On Mon, Feb 12, 2024 at 12:27 PM Aaron Gable <aaron at letsencrypt.org <_blank>> wrote: 

Thank you Wayne! I think this gets close to the sweet spot for me, personally. I've left two small comments on the ballot, but on the whole I think I like this approach. 

Thanks again, 

Aaron 

On Mon, Feb 12, 2024 at 8:18 AM Wayne Thayer via Servercert-wg <servercert-wg at cabforum.org <_blank>> wrote: 

Following up from the last SCWG teleconference, I've reviewed the feedback from the discussion [1] and voting [2] periods for ballot SC-59 Weak Key Guidance, along with the prior discussions on the "made aware" language in section 6.1.1.3 [3] and I would like to propose the following Baseline Requirements improvements: 

* Scope the 6.1.1.3 "made aware" language to "made aware via the CA's documented problem reporting mechanism". This addresses the concern that I raised by limiting how a CA can be "made aware". [4] 

* Remove the Debian requirements from the prior weak keys ballot and replace them with language that excludes Debian weak keys. Otherwise use the language from the prior ballot, with the exception of a new effective date. This consolidates feedback that CAs do desire the clarity that would have been provided by the prior ballot, but many believe that the burden for rejecting Debian weak keys exceeds the value of doing so at this point in time. 

Here's the result: https://github.com/wthayer/servercert/pull/1/files <_blank> 

Note that, while there has been discussion about completely removing weak key checking requirements, there does not appear to be a consensus to do so. 

I would appreciate everyone's feedback on the proposal, and I am also seeking endorsers. 

Thanks, 

Wayne 

[1] https://lists.cabforum.org/pipermail/servercert-wg/2023-July/003820.html <_blank> 

[2] https://lists.cabforum.org/pipermail/servercert-wg/2023-July/003857.html <_blank> 

[3] https://lists.cabforum.org/pipermail/servercert-wg/2023-July/003902.html <_blank> 

[4] https://github.com/cabforum/servercert/issues/442 <_blank> 

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