Re: [TLS] SCSV vs RI when both specified - consensus?

Marsh Ray <marsh@extendedsubset.com> Mon, 21 December 2009 18:46 UTC

Return-Path: <marsh@extendedsubset.com>
X-Original-To: tls@core3.amsl.com
Delivered-To: tls@core3.amsl.com
Received: from localhost (localhost [127.0.0.1]) by core3.amsl.com (Postfix) with ESMTP id 4128B3A6AA7 for <tls@core3.amsl.com>; Mon, 21 Dec 2009 10:46:56 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.592
X-Spam-Level:
X-Spam-Status: No, score=-2.592 tagged_above=-999 required=5 tests=[AWL=0.007, BAYES_00=-2.599]
Received: from mail.ietf.org ([64.170.98.32]) by localhost (core3.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id TDfGe8LCXMcI for <tls@core3.amsl.com>; Mon, 21 Dec 2009 10:46:55 -0800 (PST)
Received: from mho-02-ewr.mailhop.org (mho-02-ewr.mailhop.org [204.13.248.72]) by core3.amsl.com (Postfix) with ESMTP id 357413A69CA for <tls@ietf.org>; Mon, 21 Dec 2009 10:46:55 -0800 (PST)
Received: from xs01.extendedsubset.com ([69.164.193.58]) by mho-02-ewr.mailhop.org with esmtpa (Exim 4.68) (envelope-from <marsh@extendedsubset.com>) id 1NMnHC-0008Gh-Mm; Mon, 21 Dec 2009 18:46:38 +0000
Received: from [127.0.0.1] (localhost [127.0.0.1]) by xs01.extendedsubset.com (Postfix) with ESMTP id 5E0A8603A; Mon, 21 Dec 2009 18:46:37 +0000 (UTC)
X-Mail-Handler: MailHop Outbound by DynDNS
X-Originating-IP: 69.164.193.58
X-Report-Abuse-To: abuse@dyndns.com (see http://www.dyndns.com/services/mailhop/outbound_abuse.html for abuse reporting information)
X-MHO-User: U2FsdGVkX1+LVQuQyDaR13IsS4VOcyVh+NA6ch8Cy9Y=
Message-ID: <4B2FC291.8010809@extendedsubset.com>
Date: Mon, 21 Dec 2009 12:46:41 -0600
From: Marsh Ray <marsh@extendedsubset.com>
User-Agent: Thunderbird 2.0.0.23 (Windows/20090812)
MIME-Version: 1.0
To: Nasko Oskov <noskov@microsoft.com>
References: <90E934FC4BBC1946B3C27E673B4DB0E4A7EE854018@LLE2K7-BE01.mitll.ad.local> <808FD6E27AD4884E94820BC333B2DB7758409B30F1@NOK-EUMSG-01.mgdnok.nokia.com> <4B2FAAFB.5090908@pobox.com> <4B2FB265.5040203@drh-consultancy.demon.co.uk> <4B2FB68C.1000400@pobox.com> <4B2FB80E.8080300@extendedsubset.com> <B197003731D4874CA41DE7B446BBA3E84B6F5834@TK5EX14MBXW651.wingroup.windeploy.ntdev.microsoft.com>
In-Reply-To: <B197003731D4874CA41DE7B446BBA3E84B6F5834@TK5EX14MBXW651.wingroup.windeploy.ntdev.microsoft.com>
X-Enigmail-Version: 0.96.0
OpenPGP: id=1E36DBF2
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 7bit
Cc: "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] SCSV vs RI when both specified - consensus?
X-BeenThere: tls@ietf.org
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." <tls.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/listinfo/tls>, <mailto:tls-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/tls>
List-Post: <mailto:tls@ietf.org>
List-Help: <mailto:tls-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tls>, <mailto:tls-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 21 Dec 2009 18:46:56 -0000

Nasko Oskov wrote:
> Marsh Ray wrote:
>>> A server receiving a Client Hello containing multiple RI extensions 
>>> MUST generate a fatal "decode_error" alert and terminate the 
>>> connection. A server receiving a Client Hello containing the SCSV and 
>>> an RI extension is to interpret the RI as usual and ignore the SCSV.
> 
> I generally agree with this wording. I find the sentence describing multiple
> RI extensions behavior redundand, since this is already part of RFC5246:
> 
> Section 7.4.1.4:
>     There MUST NOT be more than one extension of the same type.

Oh yeah. It's also in RFC 3546 'TLS Extensions'. I looked for it the
other day but didn't see it. Now I can't find where it says what to do
when it happens.

- Marsh