Re: [TLS] DSA should die

mrex@sap.com (Martin Rex) Thu, 02 April 2015 02:17 UTC

Return-Path: <mrex@sap.com>
X-Original-To: tls@ietfa.amsl.com
Delivered-To: tls@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id EC94D1A1B12 for <tls@ietfa.amsl.com>; Wed, 1 Apr 2015 19:17:26 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -6.551
X-Spam-Level:
X-Spam-Status: No, score=-6.551 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, HELO_EQ_DE=0.35, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-0.001] autolearn=ham
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id DIqEJvW16YDR for <tls@ietfa.amsl.com>; Wed, 1 Apr 2015 19:17:25 -0700 (PDT)
Received: from smtpde02.smtp.sap-ag.de (smtpde02.smtp.sap-ag.de [155.56.68.140]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 5D8731A1A97 for <tls@ietf.org>; Wed, 1 Apr 2015 19:17:25 -0700 (PDT)
Received: from mail05.wdf.sap.corp (mail05.sap.corp [194.39.131.55]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by smtpde02.smtp.sap-ag.de (Postfix) with ESMTPS id C039F44950; Thu, 2 Apr 2015 04:17:23 +0200 (CEST)
X-purgate-ID: 152705::1427941043-0000765A-9719369D/0/0
X-purgate-size: 1609
X-purgate: clean
X-purgate: This mail is considered clean (visit http://www.eleven.de for further information)
X-purgate-Ad: Categorized by eleven eXpurgate (R) http://www.eleven.de
X-purgate-type: clean
Received: from ld9781.wdf.sap.corp (ld9781.wdf.sap.corp [10.21.82.193]) by mail05.wdf.sap.corp (Postfix) with ESMTP id B727E46418; Thu, 2 Apr 2015 04:17:23 +0200 (CEST)
Received: by ld9781.wdf.sap.corp (Postfix, from userid 10159) id AD9EC1B25A; Thu, 2 Apr 2015 04:17:23 +0200 (CEST)
In-Reply-To: <201504012115.09048.davemgarrett@gmail.com>
To: Dave Garrett <davemgarrett@gmail.com>
Date: Thu, 02 Apr 2015 04:17:23 +0200
X-Mailer: ELM [version 2.4ME+ PL125 (25)]
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset="US-ASCII"
Message-Id: <20150402021723.AD9EC1B25A@ld9781.wdf.sap.corp>
From: mrex@sap.com
Archived-At: <http://mailarchive.ietf.org/arch/msg/tls/M-ETq84U3uolA-EIKjwcPkixZyU>
Cc: tls@ietf.org
Subject: Re: [TLS] DSA should die
X-BeenThere: tls@ietf.org
X-Mailman-Version: 2.1.15
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/options/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: Thu, 02 Apr 2015 02:17:27 -0000

Dave Garrett wrote:
> On Wednesday, April 01, 2015 08:40:40 pm Stephen Farrell wrote:
>> <no-hats-except-the-330+-ciphersuites-is-crap-hat>
>> 
>> Here's a suggestion: why pick 'em off one by one? How about
>> creating a new registry that only includes stuff we think is
>> really good for TLS1.3?
> 
> I don't think a whole new registry is a good idea. The ClientHello
> has to stay the same for backwards compatibility, and cipher suites
> will need to be listed for TLS 1.2 compatibility at least.
> Creating a whole new system is only good if you can completely
> ignore the old one.
> 
> There's plenty of space in the current registry if you want to
> start over. Just say 0xD000 and up is for TLS2 suites, and all
> below are TLS1. (at this point it's definitely time for 2.0)
> Define TLS2 codepoints for valid combinations for TLS2 and the TLS1
> would be invalid to negotiate for TLS2 but in there for TLS1.

I agree that ClientHello needs to remain backwards-compatible.

But how about using the Cipher Suites registry in a more creative fashion.

For TLSv1.3, we could do the negotiation through he cipher suites list
more like this:

   0x10,0xXX    specifies a key exchange algorithm (XX) 256 codepoints
   0x12,0xYY    specifies an authentication algorithm (YY) 256 codepoints
   0x14,0xZZ    specifies a symmetric encryption scheme (ZZ) 256 codepoints
   0x16,0xQQ    specifies a mac algorithm (QQ) 256 codepoints
   0x18,0xPP    specifies a PRF algorithm (PP) 256 codepoints

(with a little room in between if we ever exceed the 256 codepoints)


-Martin