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Re: [Trans] text to address DKG's conspiring CAs attack

Rob Stradling <rob.stradling@comodo.com> Tue, 15 March 2016 15:04 UTC

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To: "David A. Cooper" <david.cooper@nist.gov>, "trans@ietf.org" <trans@ietf.org>
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From: Rob Stradling <rob.stradling@comodo.com>
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Date: Tue, 15 Mar 2016 15:04:03 +0000
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Subject: Re: [Trans] text to address DKG's conspiring CAs attack
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On 15/03/16 14:57, David A. Cooper wrote:
<snip>
> If there is an attack here, it seems that it would be as follows. Upon
> detection of the bogus certificate browsers determine that the
> subordinate CA is malicious and blacklist the cross-certificate from
> trust anchor 1 to subordinate CA, but don't blacklist any of the EE
> certificates issued by the subordinate CA (and the subordinate CA
> doesn't revoke them either). The browsers don't notice that there is a
> second cross-certificate for subordinate CA, from trust anchor 2, and so
> there continues to be a valid certification path for certificates issued
> by subordinate CA.

Yes, that is DKG's attack.

-- 
Rob Stradling
Senior Research & Development Scientist
COMODO - Creating Trust Online

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