Re: [TLS] Zero-RTT Data & PSK

Martin Thomson <martin.thomson@gmail.com> Sat, 10 September 2016 10:35 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 1A40912B074 for <tls@ietfa.amsl.com>; Sat, 10 Sep 2016 03:35:48 -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 5LMeIeKI1Z4v for <tls@ietfa.amsl.com>; Sat, 10 Sep 2016 03:35:46 -0700 (PDT)
Received: from mail-qt0-x22a.google.com (mail-qt0-x22a.google.com [IPv6:2607:f8b0:400d:c0d::22a]) (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 1D80A12B004 for <tls@ietf.org>; Sat, 10 Sep 2016 03:35:45 -0700 (PDT)
Received: by mail-qt0-x22a.google.com with SMTP id 38so52633951qte.1 for <tls@ietf.org>; Sat, 10 Sep 2016 03:35:45 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=OYuPhnKwgj5R6az3XXmDmGq6F3mHvF8BJm8xe6WR2rU=; b=u6zKa6rDB9LMgPiu3C89X9miayrwDlappjU6/PcUpH5KsrRTQA+rcaDVC0IdUgtqRz /S3/8y34G3ZdOSIR0mYkxbPqhQ/gaqSn4gUCEm9wVrmwKwKD9rEvgKKu8Z/NCqV2UrFj sH2YLtwt8DjPh1M8QRhlVJ2y0NwhIT9H2Ek0l5zYswYO4NsiFlGEcX1XWpsqbA+7UxcL 07kWKohSsOeMqHMxqIp5KdnSi0/6eHWHm3j8eMgQVZf7FkbTuzVo2cJbyBfcx4RKEuaj oFRvRTi97alQb8YVlArQ2sz2iVgidVevIYpCKRIEoRq0E3zYFMT+XORbmLPvBJXx0w/O AhpQ==
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:from:date :message-id:subject:to:cc; bh=OYuPhnKwgj5R6az3XXmDmGq6F3mHvF8BJm8xe6WR2rU=; b=B3JLGQc8/U/b7khzvUlCqSOZMp/X3nX3x0w1hg5jKcNI59QHx/P3Y+nYCIIfYrgsyU h05u/wgnM5dMKCPVr/53dqF4ULNXY2lMZC13Ndyq1qRlLzHrLKXdVuohNIos7Hq7xC7O 3xwqToZWe3P5PAJYIlSC/AxxivOM+TwvdZyuzNAbtI3bgP/KeTv3PPV90dxcdJHmQJK0 lWXrzcGXhpPPegGZmhasglq9iG30/q45Il5v/VHeGVHLXleQ42u9Ya375MAratvgFo3q pSN0DzwXko1GKl74j7ssbOWldloclznft+ERcwBc7wTjR2E635vaDRfiuAKRiqpx7AK6 4ANg==
X-Gm-Message-State: AE9vXwPWzxCsHvUfG/6gGI1I4AavOIj4po+BSkKzDSggtzncSryexO1fTFL8T6LKblQE2pDDRP+0bGQVnUv4OQ==
X-Received: by 10.200.55.169 with SMTP id d38mr9194193qtc.24.1473503745111; Sat, 10 Sep 2016 03:35:45 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.140.22.146 with HTTP; Sat, 10 Sep 2016 03:35:44 -0700 (PDT)
In-Reply-To: <2b155eb4-3268-c687-031e-6ac9928940c3@gmx.net>
References: <2b155eb4-3268-c687-031e-6ac9928940c3@gmx.net>
From: Martin Thomson <martin.thomson@gmail.com>
Date: Sat, 10 Sep 2016 20:35:44 +1000
Message-ID: <CABkgnnXfB=t+6yTCk9hSoLg9BDZS-hv4pUQHB0xh-x09xNsNYQ@mail.gmail.com>
To: Hannes Tschofenig <hannes.tschofenig@gmx.net>
Content-Type: text/plain; charset=UTF-8
Archived-At: <https://mailarchive.ietf.org/arch/msg/tls/vOCAqjDJ8DQFag9_hD8korpg6ck>
Cc: "<tls@ietf.org>" <tls@ietf.org>
Subject: Re: [TLS] Zero-RTT Data & PSK
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: Sat, 10 Sep 2016 10:35:48 -0000

On 9 September 2016 at 23:37, Hannes Tschofenig
<hannes.tschofenig@gmx.net>; wrote:
> I am wondering why I cannot use Zero-RTT with just PSK-based authentication
> (without a prior ticket change).

I think that you would need to bind more things to the key in that
case, but I assume that it would be OK if you did so.  You already
need to pair a PSK with a hash, but if you paired it with a whole
cipher suite instead and also the ALPN (which could be null), then I
see no reason not to permit 0-RTT for pure PSK.  (I think that cipher
suite + ALPN is sufficient, but someone can correct me if I missed
anything.)