[cabfpub] How old are publicly-trusted serverAuth certs when they are revoked?

Rob Stradling rob.stradling at comodo.com
Fri Feb 17 22:53:53 UTC 2017

On 17/02/17 15:33, Tom Ritter wrote:
> <Puts on his asking for more hat>
> Can it be broken out by revocation reason?

Hi Tom.  Good idea.  I'll do that on Monday.  I'm already storing the 
revocation reasons on the crt.sh DB.

> (Or is revocation reason
> considered so worthless as for this not to be a useful exercise?)

Maybe we'll be able to answer that question on Monday.  :-)

> -tom
> On 17 February 2017 at 06:42, Rob Stradling via Public
> <public at cabforum.org> wrote:
>> I found this interesting, so I thought I'd share it.  :-)
>> Yesterday I ran a query on the crt.sh database to gather data on...
>> ageWhenRevoked = trunc(revocationDate - notBefore)
>> Here are the results:
>> https://docs.google.com/spreadsheets/d/1-_2zFhUc1mKRNPOzH2alad-nX73xST-ouiy5aXRKiXs/edit?usp=sharing
>> The data set includes all revoked, unexpired serverAuth certs for which
>> there's a known (to CT) serverAuth trust chain to any root cert that's
>> trusted by at least one of the major root programs (Microsoft, Mozilla,
>> Apple, Java).
>> There are some obviously bogus revocationDates in the data set (e.g., -920
>> days before the notBefore date!)  However, if we assume that most
>> revocationDates in CRLs are accurate, these results show that, in general,
>> the likelihood of revocation decreases approximately logarithmically as a
>> certificate ages.
>> There are spikes around certificate birthdays, which are presumably due to
>> (i) revalidation failures and/or (ii) customers cancelling regular payment
>> agreements.
>> --
>> Rob Stradling
>> Senior Research & Development Scientist
>> COMODO - Creating Trust Online
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>> Public at cabforum.org
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Rob Stradling
Senior Research & Development Scientist
COMODO - Creating Trust Online
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