Re: [Trans] redacted names and my proposal

Stephen Kent <> Mon, 15 September 2014 19:02 UTC

Return-Path: <>
Received: from localhost ( []) by (Postfix) with ESMTP id 8FCD81A8765 for <>; Mon, 15 Sep 2014 12:02:52 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -5.853
X-Spam-Status: No, score=-5.853 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RP_MATCHES_RCVD=-1.652, SPF_PASS=-0.001] autolearn=ham
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id snziIhKbn2fQ for <>; Mon, 15 Sep 2014 12:02:39 -0700 (PDT)
Received: from ( []) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 29AE21A1F70 for <>; Mon, 15 Sep 2014 11:52:29 -0700 (PDT)
Received: from ([]:52877 helo=comsec.home) by with esmtp (Exim 4.77 (FreeBSD)) (envelope-from <>) id 1XTbO0-000Lbt-6L for; Mon, 15 Sep 2014 14:52:28 -0400
Message-ID: <>
Date: Mon, 15 Sep 2014 14:52:26 -0400
From: Stephen Kent <>
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.6.0
MIME-Version: 1.0
References: <> <>
In-Reply-To: <>
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Trans] redacted names and my proposal
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Public Notary Transparency working group discussion list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Mon, 15 Sep 2014 19:02:53 -0000

> Steve, my point is that the name redaction mechanism I proposed is, 
> necessarily, a one-phase protocol. The Precertificate must be logged 
> (hence phase 1), and the final certificate must not be required to be 
> logged (hence the lack of a phase 2).
Your requirements are not in conflict with my proposal. In phase 1 the 
redacted name would be
input. In Phase 2, the same input as in Phase 1 would be supplied, plus 
the serial number. My
initial characterization of the proposal didn't consider name redaction, 
and thus described
the second phase as using the issued cert. But, I tried to clarify that 
when you pointed out
that I had failed to consider redacted certs, initially.
> If the final certificate is logged, then the redacted names become 
> public. If the final certificate is not logged, then we need to at 
> least know its serial number so that it is revocable.
see my reply above.
> I don't think we can avoid requiring the serial number of the final 
> certificate to be seen by the log before the final certificate is 
> actually issued, because the embedded SCT(s) in the final certificate 
> need to prove that the log(s) have seen that serial number.
My proposal does have the serial number in the log, acquired in the 
second pass. It's not clear
that an embedded SCT needs to include the serial number, absent a more 
thorough description of
client and Monitor behavior. I agree that there is a residual 
vulnerability, noted by Ben, if the serial number is not present. But, 
there appear to be several other vulnerabilities with the
current design, based on my first cut attack analysis.