I agree. For every cert we ultimately issue, the corresponding Precert with 
matching dates must be in the minimum number of logs.

From: Erwann Abalea [mailto:[email protected]]
Sent: Wednesday, September 24, 2014 1:59 PM
To: Rick Andrews
Cc: Melinda Shore; [email protected]
Subject: Re: [Trans] Prior knowledge of certificate serial number

Well, that's possible, of course. Explaining this to an auditor may be tricky.

I wanted to make it clear that if, for example, you generate the Precert at 
date D with {notBefore=D, notAfter=D+3y}, finalize the push to all the logs on 
day D+1, and issue the final cert immediately after that, thus on day D+1, you 
MUST NOT have the final certificate with {notBefore=D+1, notAfter=D+1+3y}. It 
won't work.

2014-09-24 21:42 GMT+02:00 Rick Andrews 
<[email protected]<mailto:[email protected]>>:
Erwann,

Isn’t it possible that I log a Precertificate in one or more log servers and 
then can’t issue the final certificate, either because of log server failure or 
failure of my issuance system? The log server records my INTENT to issue a 
certificate, but I don’t think it COMPELS me to issue that certificate. I must 
be able to reject that order, change the date and serial number and start over.

We worked around the issuerName+serialNumber constraint by storing certificates 
in one table, Precertificates in another.

-Rick

From: Erwann Abalea [mailto:[email protected]<mailto:[email protected]>]
Sent: Wednesday, September 24, 2014 12:18 PM
To: Rick Andrews
Cc: Melinda Shore; [email protected]<mailto:[email protected]>
Subject: Re: [Trans] Prior knowledge of certificate serial number

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 
<[email protected]<mailto:[email protected]>>:
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 [mailto:[email protected]<mailto:[email protected]>] On 
Behalf Of Melinda Shore
Sent: Tuesday, September 23, 2014 9:08 AM
To: [email protected]<mailto:[email protected]>
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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Erwann.



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