Options for trying this out might fit under an exception, if one were
created, for "test, experimental, temporary, pilot, provisional, etc."
certificate types. 

-----Original Message-----
From: dev-security-policy
[mailto:dev-security-policy-bounces+ben=digicert....@lists.mozilla.org] On
Behalf Of Gervase Markham
Sent: Thursday, September 4, 2014 4:22 AM
To: mozilla-dev-security-pol...@lists.mozilla.org
Subject: Short-lived certs

Short-lived certs are one plank of our future revocation strategy.[0]
Currently, it is not permitted by the CAB Forum Baseline Requirements to
revocation pointers out of a cert, ever. However, this is part of the big
value of short-lived certs, as it's what unlocks their speed-increasing
potential across all browsers. (The logic is that a 3-day expiry misissued
cert with no revocation pointers has a similar risk profile to a 1-year
expiry misissued cert where the attacker has captured a valid 3-day expiry
OCSP response they can staple to it).

I've just been reviewing discussions from July 2012 on the CAB Forum mailing
lists about short-lived certs. There was some significant opposition to
removing revocation information from short-lived certs at the time (although
things may be different now, I don't know). I personally think much of that
opposition was mistaken, but the discussion nevertheless did not result in
consensus.

How should we approach the issue of short-lived certs? It seems to me we can
do the following:

0) Try and get a motion passed to change the BRs to allow short-lived certs
to not have any revocation information. This would probably require us to
review the original discussion and make a wiki page outlining our proposal
and rebutting objections. We may still run into heavy weather. We could also
discuss it at the face-to-face.

1) Write an exception in Mozilla's policy that short-lived certs don't have
to have revocation info. This would likely have no effect, because CAs would
want to continue issuing to the BRs.

2) Stop checking revocation information for short-lived certs unilaterally.
This would result in reduced take-up of the idea, because there would be no
advantage in other browsers, and one would still need to implement all the
mechanisms, both at the CA and at the site, for frequent cert renewals and
deployments.

3) Configure Firefox to not bother checking revocation information for any
cert newer than N days. This way, you can "emulate" short-lived certs by
just reissuing an X-year cert every N days or less. It also 'fixes' the
clock-skew problem in one direction, because the certs will still work for
users whose clocks are some way in the future (although their browsers would
check revocation).

4) Something else?

Gerv

[0] https://wiki.mozilla.org/CA:RevocationPlan
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