[Servercert-wg] Subscriber key pair generation by the CA

Jeremy Rowley jeremy.rowley at digicert.com
Thu May 28 18:57:12 MST 2020


I only deal in edge cases. :)

Okay, the follow up to that. What obligation does the ca have to check that a key isn't being used for tls that they generate for smime or client auth? We've been looking at key reuse (in connection with revocation) and there does seem to be some sharing of keys between certs.
________________________________
From: Ryan Sleevi <sleevi at google.com>
Sent: Thursday, May 28, 2020 7:47:24 PM
To: Jeremy Rowley <jeremy.rowley at digicert.com>
Cc: Clint Wilson <clintw at apple.com>; CA/B Forum Server Certificate WG Public Discussion List <servercert-wg at cabforum.org>
Subject: Re: [Servercert-wg] Subscriber key pair generation by the CA

Always with the edge cases ;) It's good to be thinking about that, though!

As worded, the definitions for CA say:
Certification Authority: An organization that is responsible for the creation, issuance, revocation, and management of Certificates. The term applies equally to both Roots CAs and Subordinate CAs.

So the question is which organization is generating the key. If I generate key on my MacBook Pro, using an Apple-provided copy of BoringSSL, would it be reasonable to say that Apple generated my Key Pair? I don't think so, so I think you'd be fine.

If your software makes a webservice call to some DigiCert endpoint, and this DigiCert endpoint generates a key pair and returns it, I would say yes, DigiCert did generate the key pair then.

On Thu, May 28, 2020 at 9:07 PM Jeremy Rowley <jeremy.rowley at digicert.com<mailto:jeremy.rowley at digicert.com>> wrote:
Question. Would this be violated if the CA had software that was on prem at the client that incorporated a key gen tool? Technically it's the tool generating the key, but it is software provided by the CA. Is that considered a violation?
________________________________
From: Servercert-wg <servercert-wg-bounces at cabforum.org<mailto:servercert-wg-bounces at cabforum.org>> on behalf of Ryan Sleevi via Servercert-wg <servercert-wg at cabforum.org<mailto:servercert-wg at cabforum.org>>
Sent: Thursday, May 28, 2020 4:03:31 PM
To: Clint Wilson <clintw at apple.com<mailto:clintw at apple.com>>
Cc: CA/B Forum Server Certificate WG Public Discussion List <servercert-wg at cabforum.org<mailto:servercert-wg at cabforum.org>>
Subject: Re: [Servercert-wg] Subscriber key pair generation by the CA

https://github.com/sleevi/cabforum-docs/pull/25

On Thu, May 28, 2020 at 5:06 PM Clint Wilson <clintw at apple.com<mailto:clintw at apple.com>> wrote:
We’re supportive of incorporating this into the browser alignment ballot.
Thanks for spotting and raising this, Adriano!

On May 27, 2020, at 7:04 AM, Ryan Sleevi <sleevi at google.com<mailto:sleevi at google.com>> wrote:

This seems like something easy to add to the Browser Alignment draft ballot, and something Google would support.

Mike, Clint: Do you have opinions here on behalf of Microsoft and Apple? I'm loathe to add additional requirements after y'all already reviewed, but this does seem worth tackling.

On Wed, May 27, 2020 at 9:37 AM Adriano Santoni via Servercert-wg <servercert-wg at cabforum.org<mailto:servercert-wg at cabforum.org>> wrote:

All,

tt seems to me there's an inconsistency between §5.2 of Mozilla Root Policy, which very clearly prohibits CAs from generating Subscribers' key pairs for SSL Server certs, and §6.1.2 of the BR which seemingly allows that. It would seem logical, and should not harm any CAs, if it was clarified in the BR that subscriber key pair generation by the CA is not allowed, in line with the requirement set forth in Mozilla Root Policy.

What do the people here think?

Adriano


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