On Monday, July 15, 2024 at 5:22:30 p.m. UTC-4 Tim Hollebeek wrote:

The world would be better if we all knew, IN ADVANCE, which certificates 
are automatically replaceable, and which aren’t.  This would also greatly 
streamline operations when replacements are necessary, as it removes the 
burden on making the determinations with a ticking clock, which is a 
situation that doesn’t lend itself to careful and unbiased evaluations.

The information could even be contained in a certificate extension, so that 
the rotation practices of these organizations is transparent.  

This sounds like a great idea, provided that browsers only trust 
certificates with the "never revoke" extension if the duration of the 
certificate is sufficiently short. I was thinking 2 weeks, but maybe the 20 
days proposed by Ben? Definitely less than 30 days.

If this idea is adopted, Mozilla (and other root store operators) can 
confidently add any misissued certificates without this extension to CRLite 
(or equivalent) 24 hours[1] after they are reported, regardless of whether 
the CA agrees to revoke by the deadline.

One potential downside is that this would make critical certificates stick 
out like a sore thumb, but I think on balance, the transparency is more 
valuable than the disclosure risk.  I’ve never been a huge security by 
obscurity fan, anyway.

Agreed. The two hurdles I see are convincing the CABF to allow irrevocable 
certificates in the BR, and convincing customers who use certificates on 
critical infrastructure to use certificates with a shorter duration.

I did a bit of digging, and imagine my surprise to find out that the CABF 
already[2] incorporated this idea into the BRs as "Short‐lived Subscriber 
Certificates". So make that only one hurdle. The good news is that CAs can 
start offering these "irrevocable" certificates to customers today; there 
is no need to wait for any further BR changes or root store policy updates.

Peter Harris

[1] Assuming Mozilla et al adopt Amir's proposal to disallow the 5-day 
option
[2] 
https://cabforum.org/2023/07/14/ballot-sc-063-v4-make-ocsp-optional-require-crls-and-incentivize-automation/

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