Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-rc4-01.txt
Alyssa Rowan <akr@akr.io> Thu, 02 October 2014 17:02 UTC
Return-Path: <akr@akr.io>
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 F14431A893B for <tls@ietfa.amsl.com>; Thu, 2 Oct 2014 10:02:13 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.902
X-Spam-Level:
X-Spam-Status: No, score=-1.902 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, SPF_HELO_PASS=-0.001, 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 AyyfgSt20z26 for <tls@ietfa.amsl.com>; Thu, 2 Oct 2014 10:02:12 -0700 (PDT)
Received: from entima.net (entima.net [78.129.143.175]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 496DB1A893F for <tls@ietf.org>; Thu, 2 Oct 2014 10:02:07 -0700 (PDT)
Message-ID: <542D850E.2060900@akr.io>
Date: Thu, 02 Oct 2014 18:02:06 +0100
From: Alyssa Rowan <akr@akr.io>
MIME-Version: 1.0
To: "tls@ietf.org" <tls@ietf.org>
References: <20141002005804.2760C1AE9D@ld9781.wdf.sap.corp> <BA2DFF33-7B0C-4E87-9C0E-215933AED88F@akr.io> <2A0EFB9C05D0164E98F19BB0AF3708C71D2F8F7E83@USMBX1.msg.corp.akamai.com> <CADMpkcJEt4e7LJAY+FsFcbyQE2x3SXsaOW3bffV4U2oN9EUKrg@mail.gmail.com>
In-Reply-To: <CADMpkcJEt4e7LJAY+FsFcbyQE2x3SXsaOW3bffV4U2oN9EUKrg@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit
Archived-At: http://mailarchive.ietf.org/arch/msg/tls/CCJ-Tq0-5r7NebLI935wKsnijUg
Subject: Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-rc4-01.txt
X-BeenThere: tls@ietf.org
X-Mailman-Version: 2.1.15
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/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 Oct 2014 17:02:14 -0000
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 2 October 2014 15:44:37 BST, Bodo Moeller <bmoeller@acm.org> wrote: > It seems to me that having a bit of a gray area then is > unavoidable ... and often you *do* need some latitude in > backwards-compatible cases, assuming you support these to achieve > backwards-compatibility. As I've pointed out, if you're forced into backwards compatibility with rusty legacy, 3DES is, though crappy, a less crappy choice than RC4. As Rich points out, just because legacy devices are indeed out there doesn't mean that they do TLS safely, and doesn't mean we shouldn't prohibit unsafe practice like using weak ciphers. > (www.microsoft.com, for example, does allow RC4 cipher suites when > using TLS 1.0, which would be incompatible with that MUST NOT, > since it expressly applies to TLS 1.0 too.) This draft is a warning to implementers and deployers of TLS that they MUST change their allowed ciphersuites to completely exclude RC4, because RC4 isn't safe enough to use in TLS (or really for any purpose anymore). Pointing to examples of RC4 still being allowed in the wild only further demonstrates the need for this draft as-is. > If the spec isn't aligned with reality, that's a bit of a problem. > You shouldn't have to interpret a MUST NOT as a SHOULD NOT. Reality is, unfortunately, that RC4 should have obsoleted years ago. That is indeed a bit of a problem - one we now need to fix rapidly. > Maybe the spec should have strict MUST NOT requirements for TLS > 1.2, but make mere recommendations for the legacy protocols? No, not sure I follow your reasoning here: RC4 is no less weak when used with SSLv3 or TLS 1.0 than with TLS 1.2. Might even be weaker, if there's a way to trick a server into selecting it (hence the fallback SCSV draft). I see no reason the prohibition ought not be absolute. Regarding obsolete ciphers such as RC2 and DES, I don't think the need to prohibit them is quite as urgent, because people aren't actually using them in the wild. (Well, not _many_ people, anyway.) I would indeed support their deprecation - but perhaps in a separate document, as I'm concerned that any unnecessary delay with this one is another day that RC4's still actively being used by many, even when better alternatives are available - which is another day of traffic Eve can record - and, I fear, break, now or any time later at their leisure. The sooner we can proceed, the sooner we can start working to fix that. - -- /akr -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJULYUNAAoJEOyEjtkWi2t6cZYQAK/LJRHi9BjIDkyQgTGiSRrl D7tawBqIyR/0IErV+bz1UrIvCifx4Lrn99qscMEfuklRjEmJ0QJa2qAYYB51LPOi +zxphHrXwSA3iofgTqawPLq3A+N6mHM38TBKhhxRW8oF8Y7zcNtvIAFRAWZ3f5zM vAN9GW4MJLbDYpbu4mxsJ1qLhZ8+Ojo3IIcJnhhhZYJ6pdlwoQzWlUOzd9itdbbo Nn1DnZUvJBIHS8uGclFamZDlg+f4b4Djy6msQH1C2VdQkgaZxAHr/E+gaU/whpTY Qfc9FooyaEH5tpAiKDfcTjyhhgWatsJQhx39I+Mt/t9Ht+H7FR3kxHB4XRCgiSyg ASvobV/ATo3aSflqeUrO7myS7cJWXH2gHCVKCXIw0JxIT40j5q08VtUsd9b1Db9Z HaXWibvBYcngkGvpHC5CW+P7vNDP0x4wUPNaa/w8KBO7dZcqwFKC7BHpcekIKt4A yQjiPAG2tXDmqd5Y9GykcJU0kFZucPbulcGnNW1KeAoZhgBmUzsDVq0gw6U+VQ/J 1vFcwG2DlCl1ICBxHEjCcNAiJ3K0MX5Dz6wMD2NaQ1CvlqU3g7HWHJha0VbMsQns P1SLllT8Kjmm/KpJyqiYE0hbuYfWnUPv5BeKW5eVuBzZA2D8maHSBilIZIvPbv8K a1qiinNciHhRIs14X8kV =GfyS -----END PGP SIGNATURE-----
- [TLS] I-D Action: draft-ietf-tls-prohibiting-rc4-… internet-drafts
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Martin Rex
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Watson Ladd
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Salz, Rich
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Alyssa Rowan
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Hanno Böck
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Bodo Moeller
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Bodo Moeller
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Alyssa Rowan
- [TLS] adopting ChaCha20 as a WG item was: I-D Act… Nikos Mavrogiannopoulos
- Re: [TLS] adopting ChaCha20 as a WG item was: I-D… Yoav Nir
- Re: [TLS] adopting ChaCha20 as a WG item was: I-D… Nikos Mavrogiannopoulos
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Salz, Rich
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Bodo Moeller
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Alyssa Rowan
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Andrei Popov
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Martin Rex
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Bodo Moeller
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Alyssa Rowan
- Re: [TLS] adopting ChaCha20 as a WG item was: I-D… Yoav Nir
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Geoffrey Keating
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Viktor Dukhovni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Watson Ladd
- [TLS] why Chacha20-SHA1 was: adopting ChaCha20 as… Nikos Mavrogiannopoulos
- Re: [TLS] why Chacha20-SHA1 was: adopting ChaCha2… Joachim Strömbergson
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Yoav Nir
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Hubert Kario
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Hubert Kario
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Viktor Dukhovni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Watson Ladd
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Viktor Dukhovni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Peter Gutmann
- Re: [TLS] why Chacha20-SHA1 was: adopting ChaCha2… Brian Smith
- Re: [TLS] why Chacha20-SHA1 was: adopting ChaCha2… Watson Ladd
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… James Cloos
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Paul Lambert
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Viktor Dukhovni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Ryan Carboni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Stephen Farrell
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Carl S. Gutekunst
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Watson Ladd
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… James Cloos
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Andrei Popov
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Martin Rex
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Yoav Nir
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Hubert Kario
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Martin Rex
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Ralph Holz
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Ronald del Rosario
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Chris Newman
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Joseph Salowey
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Andrei Popov
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Watson Ladd
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Andrei Popov
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Salz, Rich
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Alyssa Rowan
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Yoav Nir
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Ryan Carboni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Viktor Dukhovni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Ryan Carboni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Salz, Rich
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Salz, Rich
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Stephen Farrell
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Paterson, Kenny
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Viktor Dukhovni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Salz, Rich
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Hubert Kario
- [TLS] Fw: I-D Action: draft-ietf-tls-prohibiting-… Blumenthal, Uri - 0558 - MITLL
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Stephen Checkoway
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Salz, Rich
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Stephen Farrell
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Salz, Rich
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Stephen Farrell
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Viktor Dukhovni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Daniel Kahn Gillmor
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Viktor Dukhovni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Salz, Rich
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Daniel Kahn Gillmor
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Viktor Dukhovni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Viktor Dukhovni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Daniel Kahn Gillmor
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Viktor Dukhovni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Geoffrey Keating
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Viktor Dukhovni
- Re: [TLS] I-D Action: draft-ietf-tls-prohibiting-… Blumenthal, Uri - 0558 - MITLL