[Servercert-wg] Ballot SC23: Precertificates

Ryan Sleevi sleevi at google.com
Wed Oct 23 07:35:45 MST 2019


We're *not* supportive of attempting to define a Precert as a Cert. That
is, I don't see us being able to vote in favor of Wayne's current ballot.

That has a host of undesirable interactions in ways that don't make sense.
Again, the example I raised is one that I think is unaddressed and would be
very unreasonable, but the natural reading: that Precert Signing
Certificates need to operate OCSP responders, and that Precerts issued by
Precert Signing Certs are BR violations (due to RFC 5280 due to the
interaction between the Issuer field of the Precert vs the CA that signed

The very design of RFC 6962 is that Precertificates are-not Certificates;
they're something "else" (like an OCSP response or a CRL). From a policy
perspective, they're implied proof of an equivalent certificate, but that's
very different than stating they are Certificates. It's that subtlety that
has tripped up some, but not all, and so it's great thing to clarify.

However, calling Precerts as Certs is bad, and will cause more CAs to
violate the BRs than would not.

On Wed, Oct 23, 2019 at 3:10 AM Dimitris Zacharopoulos (HARICA) via
Servercert-wg <servercert-wg at cabforum.org> wrote:

> Sure, other CAs have expressed concerns about that so ultimately I leave
> it up you to you, Rob and Wayne to decide how to proceed.
> For what it's worth, we might need to examine any unintended consequences
> from this proposal, for example the fact that revoked Pre-certificates are
> not included in CRLs and adding revoked Pre-certificates in CRLs might
> increase their size, etc.

For what it's worth, this is one of the few places where it *does* make
sense to be clear.  It's not revocation information for a Precertificate,
however; it's a presumption of an equivalent Certificate, and revocation
information for that certificate. If a Precertificate is signed, and it's
seen as signed proof that an equivalent certificate exists, and that
certificate needs to be revoked, the CA should be adding that to CRLs, just
like they should be adding it to OCSP. The risk described here is only if
the CA is signing precerts that equal misissuance, and that would be very
bad for reasons other than CRL size.
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