Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fast-Track" draft
Martin Rex <mrex@sap.com> Fri, 19 February 2010 18:19 UTC
Return-Path: <mrex@sap.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 55C0D3A7FE6 for <tls@core3.amsl.com>; Fri, 19 Feb 2010 10:19:55 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -10.22
X-Spam-Level:
X-Spam-Status: No, score=-10.22 tagged_above=-999 required=5 tests=[AWL=0.029, BAYES_00=-2.599, HELO_EQ_DE=0.35, RCVD_IN_DNSWL_HI=-8]
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 sLBXDIjMzSFR for <tls@core3.amsl.com>; Fri, 19 Feb 2010 10:19:54 -0800 (PST)
Received: from smtpde01.sap-ag.de (smtpde01.sap-ag.de [155.56.68.171]) by core3.amsl.com (Postfix) with ESMTP id 296C83A7D3B for <tls@ietf.org>; Fri, 19 Feb 2010 10:19:53 -0800 (PST)
Received: from mail.sap.corp by smtpde01.sap-ag.de (26) with ESMTP id o1JILaqt008987 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 19 Feb 2010 19:21:36 +0100 (MET)
From: Martin Rex <mrex@sap.com>
Message-Id: <201002191821.o1JILZuw019703@fs4113.wdf.sap.corp>
To: brian@briansmith.org
Date: Fri, 19 Feb 2010 19:21:35 +0100
In-Reply-To: <4B7ECFEF.50502@briansmith.org> from "Brian Smith" at Feb 19, 10 11:52:47 am
MIME-Version: 1.0
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 8bit
X-Scanner: Virus Scanner virwal07
X-SAP: out
Cc: DPKemp@missi.ncsc.mil, tls@ietf.org
Subject: Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fast-Track" draft
X-BeenThere: tls@ietf.org
X-Mailman-Version: 2.1.9
Precedence: list
Reply-To: mrex@sap.com
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: Fri, 19 Feb 2010 18:19:55 -0000
Brian Smith wrote: > > Stefan Santesson wrote: > > Brian, > > > > The use of hash functions in this draft does not require collision > > resistance. > > This is actually quite easy to prove. > > Nobody is questioning that at all. > > My points are: > > 1. As long as this web page on the NIST website says, basically, "don't > use SHA-1 for anything," people will want to disable SHA-1 whenever they > can. It doesn't matter that this page on the website isn't the official > NIST recommendation on the matter. It doesn't matter that NIST > recommendations are only binding for federal government work. It doesn't > matter that the official NIST recommendation (SP 800-107) is more > limited in its recommendations against SHA-1. People will still want to > disable it. Like I said many messages before, even if it isn't a > technical problem, it is a social problem. And, that problem can be > easily avoided. There is some confusion about what problems there are with SHA-1. But doing as you suggest, you are just adding massively to that confusion, depicting SHA-1 as being universally bad. My memory was, that NIST's recommendation was to no longer issue certs with sha-1 as a signature algorithm after 2010. I don't know what you mean by "disabling SHA-1", but most software is likely to not have such a configuration settings -- and those software that does is likely to no longer interoperate securely with others if SHA-1 would be universally disabled. What you are asking for is a policy like this: "We can no longer let you use HTTPS because it makes use of TLSv1.0 with contains the universally insecure SHA-1 algorithm. Please use HTTP URLs instead." > > 2. It doesn't make sense to require SHA-1 support to be added to > implementations that don't need SHA-1 for any other purpose. TLS 1.2 > doesn't require SHA-1 for anything, so you can build a compliant and > useful implementation without SHA-1 support. There are technical > advantages to doing so. Obviously, this isn't practical for > general-purpose web browsers, but it is practical for many other uses. You are mistaken. SHA-1 is a MUST implement for TLSv1.2. TLS uses a SHA-256 only PRF and provides cipher suites with SHA-256, but limiting an implmentation to that subset of TLSv1.2 is only an option for the consumer of the technology, not an option for the implementor. Limiting your application to allow only protocol version TLSv1.2 and only ciphersuites with SHA-256 hash and support of Certs with signature algorithms using sha-256 is going to make your application non-interoperable with 99,8% of the installed base of TLS-enables apps. And that situation is going to change only at a fairly slow pace in the future. So it could be that the particular isolated environment that you are looking at might be happy with such a configuration, but for the average consumer of this technology it just would not make any sense. And mind you, for your isolated environment, you can certainly implement and use the caching extension with SHA-256 only, the proposal has the necessary protocol options. -Martin
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Simon Josefsson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Adam Langley
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Nikos Mavrogiannopoulos
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Adam Langley
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Michael D'Errico
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Nikos Mavrogiannopoulos
- Re: [TLS] Android's cut-through mode & "RequestTi… Brian Smith
- [TLS] Stream multiplexing extension RE: SPDY / Ne… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- [TLS] TLS Performance (was Re: draft-ietf-tls-cac… Michael D'Errico
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Adam Langley
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Adam Langley
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Adam Langley
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Kemp, David P.
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Martin Rex
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- [TLS] Cached-info substitution Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Kemp, David P.
- Re: [TLS] Cached-info substitution Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Martin Rex
- Re: [TLS] Cached-info substitution Adam Langley
- Re: [TLS] Cached-info substitution Brian Smith
- Re: [TLS] Cached-info substitution Adam Langley
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] Cached-info substitution Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Martin Rex
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Martin Rex
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Kemp, David P.
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Martin Rex
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Martin Rex
- [TLS] RFC 5077 (was Re: draft-ietf-tls-cached-inf… Michael D'Errico
- Re: [TLS] Cached-info substitution Adam Langley
- Re: [TLS] Cached-info substitution Wan-Teh Chang
- Re: [TLS] Cached-info substitution Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Simon Josefsson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Martin Rex
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Kemp, David P.
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Marsh Ray
- Re: [TLS] [POSSIBLE SPAM] Re: draft-ietf-tls-cach… Kemp, David P.
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Marsh Ray
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Yoav Nir
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Simon Josefsson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Martin Rex
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Simon Josefsson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Simon Josefsson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Joseph Salowey (jsalowey)
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Brian Smith
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Martin Rex
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Simon Josefsson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Donald Eastlake
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Joseph Salowey (jsalowey)
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Marsh Ray
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Simon Josefsson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Stefan Santesson
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Adam Langley
- Re: [TLS] draft-ietf-tls-cached-info-02 / New "Fa… Michael D'Errico