So, this is something that would be helpfully clarified via either an IETF 
draft, or clarifications in the BRs.  There are various things in the OCSP RFCs 
and even the BRs that can be read as precluding good OCSP responses for 
pre-certificates, although the situation is unclear since the relevant sections 
are blissfully ignorant of CT, and the correct behavior here was unfortunately 
left out of RFC 6962, which should have clarified this.

Happy to help draft something.  There are some interesting complexities once 
you dig deeper.

-Tim

> -----Original Message-----
> From: dev-security-policy <dev-security-policy-boun...@lists.mozilla.org> On
> Behalf Of Jeremy Rowley via dev-security-policy
> Sent: Thursday, September 12, 2019 1:46 PM
> To: Alex Cohn <a...@alexcohn.com>
> Cc: mozilla-dev-security-pol...@lists.mozilla.org; Wayne Thayer
> <wtha...@mozilla.com>
> Subject: RE: DigiCert OCSP services returns 1 byte
> 
> The language says you have to provide the response for the cert as if it 
> exists,
> but the reality is that sending a response for the precert is the same as
> calculating the result for the certificate as if it exists and sending that. 
> They are
> the same thing because the precert is treated the same as the final cert if 
> the
> final cert doesn’t exist.
> 
> I believe the intent is that a CT-naïve OCSP checker would work normally when
> presented with a precert or a certificate. Afterall, a precert is really just 
> a
> certificate with a special extension.
> 
> From: Alex Cohn <a...@alexcohn.com>
> Sent: Thursday, September 12, 2019 9:25 AM
> To: Jeremy Rowley <jeremy.row...@digicert.com>
> Cc: Wayne Thayer <wtha...@mozilla.com>; mozilla-dev-security-
> pol...@lists.mozilla.org
> Subject: Re: DigiCert OCSP services returns 1 byte
> 
> On Wed, Sep 11, 2019 at 10:09 PM Jeremy Rowley via dev-security-policy
> <dev-security-policy@lists.mozilla.org<mailto:dev-security-
> pol...@lists.mozilla.org>> wrote:
> This means, for example, that (i) a CA must provide OCSP services and
> responses in accordance with the Mozilla policy for all pre-certificates as if
> corresponding certificate exists and (ii) a CA must be able to revoke a pre-
> certificate if revocation of the certificate is required under the Mozilla 
> policy
> and the corresponding certificate doesn't actually exist and therefore cannot
> be revoked.
> 
> Should a CA using a precertificate signing certificate be required to provide
> OCSP services for their precertificates? Or is it on the relying party to 
> calculate
> the proper OCSP request for the final certificate and send that instead? In
> other words, should we expect a CT-naïve OCSP checker to work normally
> when presented, e.g., with https://crt.sh/?id=1868433277?
> 
> Alex
> _______________________________________________
> dev-security-policy mailing list
> dev-security-policy@lists.mozilla.org
> https://lists.mozilla.org/listinfo/dev-security-policy

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