Re: [TLS] no fallbacks please [was: Downgrade protection, fallbacks, and server time]

Martin Thomson <martin.thomson@gmail.com> Fri, 03 June 2016 03:29 UTC

Return-Path: <martin.thomson@gmail.com>
X-Original-To: tls@ietfa.amsl.com
Delivered-To: tls@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id BE3EC12D1A0 for <tls@ietfa.amsl.com>; Thu, 2 Jun 2016 20:29:34 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.7
X-Spam-Level:
X-Spam-Status: No, score=-2.7 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com
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 t7Wv0Uw0Kt2m for <tls@ietfa.amsl.com>; Thu, 2 Jun 2016 20:29:32 -0700 (PDT)
Received: from mail-qk0-x233.google.com (mail-qk0-x233.google.com [IPv6:2607:f8b0:400d:c09::233]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id A16F512D15C for <tls@ietf.org>; Thu, 2 Jun 2016 20:29:32 -0700 (PDT)
Received: by mail-qk0-x233.google.com with SMTP id n63so48593484qkf.0 for <tls@ietf.org>; Thu, 02 Jun 2016 20:29:32 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc; bh=hOxEj37AuKkbK3uvNHbtPTsjjDGTztRxO/lA6gtajhM=; b=u+vosmbXawSs2QgXj00FdbdMyEfyBJ8KAnxeozXaW6/Pmwjj1aO60DglKjLgX5yxEo rgzqVpt5ZhfYiJzFLLYqcryb/JmT3BAlG2T75VaD3Jocwxr6NIli66MrmjK/PGBSeLMz g8CVRnbP02F0j565Meo4AXQEfcCZloTDgAo4f4YUizOegmI5iwtsV6zd9gy2j4wYq/Wq NderUgRpHGD5KGJD7khFwPRV5wGjbkPngxRDqj3ugjHm3CjgbDEHHtgz5fguSch2liE3 3C/6cUkavN4MwJRLMZ2MSHR56rwfpj6vAQc3WPF/Belp7R08BuAMRS4nHd7+DjRnDQsv ah2g==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc; bh=hOxEj37AuKkbK3uvNHbtPTsjjDGTztRxO/lA6gtajhM=; b=jWnK3Foxfdf7Y94fZzzcejr4XrVKcJ42oAbsmBO0rFbu+jMxNc083lV10mZzxyi1v/ M6NiQL+v0y5T8c9AZyAnxAjZMjc0RvPvqszBMeflQNjDoZV+TKmJT3D0yKVac+GBQmZs 6PuUgdOnft+Jg42nUCq3p2hG4bmJPId5aegTJwPZt1FrJZROrZ2BH/JQPpR4SauGvqdX rmViCkvzyoSL46pvWcvd0GnvBSrPVCRL/yPOwj+LjclS4nTpLtE4/kzXaTuK6oVchzzm ZXH0n7zMYW6oMMh8JyDx7bDkNXLCggg7VnXnoe+OjL+JWoZEFWSM7tL3nSFJaLQ5xIf2 ggww==
X-Gm-Message-State: ALyK8tLDPoIG0jVrQwQx8pUZym5N28e3yg+a+uTkeUMx7OfVsDC8a2GKcPH+lJnWA8/BrhAMXcl4kyvzYf4AoA==
MIME-Version: 1.0
X-Received: by 10.55.135.7 with SMTP id j7mr1301845qkd.32.1464924571837; Thu, 02 Jun 2016 20:29:31 -0700 (PDT)
Received: by 10.140.104.110 with HTTP; Thu, 2 Jun 2016 20:29:31 -0700 (PDT)
In-Reply-To: <CAF8qwaASpH3Fapo61TDBuF35++GyMbZa4c-9Uy-JZ8CKywpAFw@mail.gmail.com>
References: <CAF8qwaDuGyHOu_4kpWN+c+vJKXyERPJu-2xR+nu=sPzG5vZ+ag@mail.gmail.com> <1464852691.5804.1.camel@redhat.com> <DBDC810F-B93F-4294-AB43-87B04DFE88D1@gmail.com> <3713097.ExV049UdFl@pintsize.usersys.redhat.com> <CAF8qwaASpH3Fapo61TDBuF35++GyMbZa4c-9Uy-JZ8CKywpAFw@mail.gmail.com>
Date: Fri, 3 Jun 2016 13:29:31 +1000
Message-ID: <CABkgnnXs5UBPZRzPoyiVs1R7arBcPV7WuEY692SHkj=doW6bwQ@mail.gmail.com>
From: Martin Thomson <martin.thomson@gmail.com>
To: David Benjamin <davidben@chromium.org>
Content-Type: text/plain; charset=UTF-8
Archived-At: <http://mailarchive.ietf.org/arch/msg/tls/P20XEG7A1W7lBYL1rxPoaLtqtBs>
Cc: "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] no fallbacks please [was: Downgrade protection, fallbacks, and server time]
X-BeenThere: tls@ietf.org
X-Mailman-Version: 2.1.17
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: <https://mailarchive.ietf.org/arch/browse/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, 03 Jun 2016 03:29:35 -0000

On 3 June 2016 at 01:07, David Benjamin <davidben@chromium.org>; wrote:
> But reality is what it is. The Law of the Internet is the last thing that
> changed is blamed. We have a limited "budget" we can spend breaking things
> (otherwise I'd have removed almost everything by now!) and there is no
> chance I can break all the hosts I found.

FWIW, I agree.  This has a bit of an explanation of the forces at play
here: https://annevankesteren.nl/2016/05/client-server