Re: [TLS] RESOLVED (Re: [sasl] lasgt call comments (st Call:

Martin Rex <> Tue, 03 November 2009 12:43 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 96D5D28C17F; Tue, 3 Nov 2009 04:43:04 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -6.193
X-Spam-Status: No, score=-6.193 tagged_above=-999 required=5 tests=[AWL=0.056, BAYES_00=-2.599, HELO_EQ_DE=0.35, RCVD_IN_DNSWL_MED=-4]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id dzzVMJkPj1QD; Tue, 3 Nov 2009 04:43:03 -0800 (PST)
Received: from ( []) by (Postfix) with ESMTP id 2C54528C149; Tue, 3 Nov 2009 04:43:02 -0800 (PST)
Received: from by (26) with ESMTP id nA3ChHnF008423 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 3 Nov 2009 13:43:17 +0100 (MET)
From: Martin Rex <>
Message-Id: <>
Date: Tue, 03 Nov 2009 13:43:16 +0100
In-Reply-To: <> from "Peter Gutmann" at Nov 3, 9 10:06:39 pm
MIME-Version: 1.0
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 8bit
X-Scanner: Virus Scanner virwal06
X-SAP: out
Subject: Re: [TLS] RESOLVED (Re: [sasl] lasgt call comments (st Call:
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: "This is the mailing list for the Transport Layer Security working group of the IETF." <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Tue, 03 Nov 2009 12:43:04 -0000

Peter Gutmann wrote:
> Martin Rex <> writes:
> >Microsoft's implementation (which could be the one referred to by
> >Larry's implementation) has a silly design flaw in its TLS renogiation,
> >and I'm not sure that the previous text is a way to fix it.
> >
> >It is possible to configure Microsoft IIS in a fashion so that it
> >will first perform a TLS handshake with a server-only authentication,
> >and after having received the HTTP request, it will re-negotiate and
> >ask for a client certificate.
> It's not necessarily a design flaw, AFAIK it's a performance optimisation to 
> avoid the server having to maintain state/leave a connection open for an 
> arbitrary amount of time while the user fumbles around with smart cards and 
> certificates and whatnot.

I'm sorry if I have explained myself so badly.

I was NOT talking about the closing of the connection while the
client is prompting the user for selection of a client certificate.
That is actually an extremely appreciated feature of MSIE (the Browser),
a point where most other web browsers are broken in that they
stall the server in the middle of a TLS handshake for an indefinite
amount of time while performing user interaction.

I was refering to a design flaw in server-side session caching of
Microsoft IIS (the Server) when it is configured to perform renegotiation
in order to obtain a client certificate after having seen and evaluated
the request.