Re: [Trans] Certificate and Precertificate extensions ordering

Rob Stradling <rob.stradling@comodo.com> Thu, 11 September 2014 11:26 UTC

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Date: Thu, 11 Sep 2014 12:26:38 +0100
From: Rob Stradling <rob.stradling@comodo.com>
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To: Ben Laurie <benl@google.com>, Eran Messeri <eranm@google.com>
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Cc: Erwann Abalea <eabalea@gmail.com>, "trans@ietf.org" <trans@ietf.org>
Subject: Re: [Trans] Certificate and Precertificate extensions ordering
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On 11/09/14 12:17, Ben Laurie wrote:
> On 11 September 2014 11:56, Eran Messeri <eranm@google.com> wrote:
>> The poison extension is removed from the Precertificate prior to the log
>> producing an SCT over it, so a client never has to know about it. What the
>> TLS client has to do is to remove the "embedded SCTs" extension  from the
>> certificate prior to validating the signature.
>
> This does imply that the remaining extensions have to be in the same
> order in both precert and cert, I think?

Yes.

I think this bit...
   "The Precertificate is constructed from the certificate to be issued
    by adding a special critical poison extension..."
...implies that the other extensions shouldn't be shuffled, but should 
we make it more explicit?

>> On Thu, Sep 11, 2014 at 11:40 AM, Erwann Abalea <eabalea@gmail.com> wrote:
>>>
>>> Bonjour,
>>>
>>> It seems there's no constraint on the order of extensions in the final
>>> certificate regarding to the Precert.
>>> Won't it be problematic if the browser wants to validate the SCT
>>> signatures by constructing the Precert from the final certificate? Where
>>> should a CA add the poisonous extension? And the future "redactedlabels"
>>> extension (it has no name)?
>>>
>>> --
>>> Erwann.
>>>
>>> _______________________________________________
>>> Trans mailing list
>>> Trans@ietf.org
>>> https://www.ietf.org/mailman/listinfo/trans
>>>
>>
>>
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>
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-- 
Rob Stradling
Senior Research & Development Scientist
COMODO - Creating Trust Online
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