[cabfpub] Ballot for limited exemption to RFC 5280 for CTimplementation

Rob Stradling rob.stradling at comodo.com
Thu Sep 18 09:08:00 UTC 2014

On 18/09/14 04:55, Brian Smith wrote:
> On Wed, Sep 17, 2014 at 7:01 PM, Kirk Hall wrote:
>     __
>     1. Amend the Definitions as follows:____
>     __ __
>     Valid Certificate:**A Certificate that passes the validation
>     procedure specified in RFC 5280 */_(except for the limited exemption
>     provided in Appendix B)._/*
> This seems like a bad and unnecessary idea to me. The trans working
> group is already debating discussing the format of precertificates so
> that they are not syntactically-valid certificates for the
> standards-track CT mechanism. The version of CT Google and the CAs have
> implemented is an experiment, not a standard or proposed standard. The
> CAs can work around this issue by using the OCSP-based CT mechanism
> instead of the precertificate mechanism.

Hi Brian.

It would be great if OCSP Stapling was already deployed sufficiently 
ubiquitously for this workaround to be viable.  Unfortunately, it's 
still not.

> Finally, IIUC, the only
> negative consequence of this that EV certificates won't get the EV
> indicator in Google Chrome. It doesn't affect any other clients, IIUC.

Correct.  However, EV certificate holders really don't want to lose the 
EV indicator in Chrome!

> IMO, it makes more sense to change the experiment than it does to
> (effectively) change the fundamental standards that all CABForum work is
> based on.

Maybe so, but I don't see any sign of Google's CT/EV plan being 
derailed.  Remember, it's already been 3 years since the DigiNotar 

> Note that the use or non-use of a precertificate signing certificate has
> no bearing (IIUC) on whether the precertificate would be a duplicate of
> the final certificate, because the difference between Option 1 and
> Option 2 doesn't affect the issuer and serial number fields of the
> precertificate.

Not quite.  The Precertificate's serial number is indeed the same with 
both options.  However, the Precertificate's issuer name and AKI are 
different, depending on whether option 1 or 2 is used.


Rob Stradling
Senior Research & Development Scientist
COMODO - Creating Trust Online
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