Re: [Trans] Write-up of the "Strict CT" variant

[Eran Messeri <[e-mail]>]

On Tue, May 23, 2017 at 2:26 PM, Ryan Sleevi <[e-mail]> wrote:

> A variation of this to consider:
>
> - CAs already MUST update their OCSP responses on a 3.5 day interval (by
> virtue of Microsoft's program requirements), which I'm working on codifying
> with the Baseline Requirements since they are, effectively, a baseline that
> Microsoft has defined
>
> A UA could define that:
> - CAs MUST include the SCT and an inclusion proof from that SCT to one of
> the 'blessed' STHs
>
In the OCSP response, I assume?

> - There is a rolling two week window of 'blessed' STHs (using whatever
> selection scheme appropriate)
>
> Whether this is the opt-in server basis or for all connections, this could
> provide a privacy-preserving proof-of-inclusion with stronger guarantees.
> This is built on existing 6962-bis primitives (AIUI), and simply an
> exercise in UA policy. Further, this does not inhibit nor substantially
> change the implementation story for other user agents - which could still
> support other forms of SCT delivery (e.g. precerts, TLS) with asynchronous
> inclusion proof checking.
>
Seems to me like a simpler way to achieve the same requirements, and so
favourable. It does depend on clients fetching OCSP responses / OCSP
stapling by servers, correct?