Re: [Trans] Prior knowledge of certificate serial number

Erwann Abalea <> Wed, 24 September 2014 19:17 UTC

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Date: Wed, 24 Sep 2014 21:17:31 +0200
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From: Erwann Abalea <>
To: Rick Andrews <>
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Cc: Melinda Shore <>, "" <>
Subject: Re: [Trans] Prior knowledge of certificate serial number
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Bonsoir Rick,

If the dates set in the final certificate is different than the dates used
in the Precertificate, the browser won't be able to verify the SCT. That
means that all the Precertificates you publish for the same final
certificate MUST be identical in every aspect.

We also have an issuerName+serialNumber constraint in database, that's why
Option 1 isn't an easy task.

2014-09-24 21:05 GMT+02:00 Rick Andrews <>om>:

> Melinda,
> At Symantec we know the serial number prior to issuance, because we
> generate it and put it in the TBSCertficate.
> The only problem we have with serial numbers is in the case where we fail
> to get enough SCTs to put in the cert. We'll retry the operation up to 48
> hours, but we always want to set the notBefore date to the day we issue the
> cert, so we don't short-change customers (believe me, there are customers
> who notice). But if we update the notBefore date and retry the logging
> operation, we have to change the serial number too. Otherwise we might log
> different certs with the same serial number in different logs, and that
> would be inconsistent. However, we use the combination of issuer name and
> serial number as a unique key for that order in our database, so changing
> serial numbers is challenging. The simpler alternative is to reject the
> order and ask the customer to start over, but that's a bad customer
> experience. We're not sure yet how we'll solve this, but we'll figure
> something out (we don't expect 6962-bis to provide a solution). And while
> we hope that this situation will occur very rarely
>  , it could happen, so we're preparing for it.
> -Rick
> -----Original Message-----
> From: Trans [] On Behalf Of Melinda Shore
> Sent: Tuesday, September 23, 2014 9:08 AM
> To:
> Subject: [Trans] Prior knowledge of certificate serial number
> One of the questions that's come up is whether or not it's reasonable to
> expect that CAs will (or can) have knowledge of a certificate's serial
> number prior to issuance - it's one of the basic questions that needs to be
> considered in the context of the precertificate discussions.
> We'd be grateful if any CAs (particularly ones with a CT implementation
> either in the works or planned) could give some feedback on that.
> Thanks,
> Melinda
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