IETF Logo Mail Archive

Re: [dns-privacy] DNS + 0-RTT

Shane Kerr <shane@time-travellers.org> Wed, 13 April 2016 12:09 UTC

Return-Path: <shane@time-travellers.org>
X-Original-To: dns-privacy@ietfa.amsl.com
Delivered-To: dns-privacy@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id AE63912D928 for <dns-privacy@ietfa.amsl.com>; Wed, 13 Apr 2016 05:09:07 -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 autolearn_force=no
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 K1B3KuyDh9J5 for <dns-privacy@ietfa.amsl.com>; Wed, 13 Apr 2016 05:09:06 -0700 (PDT)
Received: from time-travellers.nl.eu.org (c.time-travellers.nl.eu.org [IPv6:2a02:2770::21a:4aff:fea3:eeaa]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 4338712D707 for <dns-privacy@ietf.org>; Wed, 13 Apr 2016 05:09:06 -0700 (PDT)
Received: from [2001:470:78c8:2:224:9bff:fe13:3a9c] (helo=pallas.home.time-travellers.org) by time-travellers.nl.eu.org with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.80) (envelope-from <shane@time-travellers.org>) id 1aqJbT-0005BH-Ad; Wed, 13 Apr 2016 12:09:03 +0000
Date: Wed, 13 Apr 2016 14:09:00 +0200
From: Shane Kerr <shane@time-travellers.org>
To: Colm MacCárthaigh <colm@allcosts.net>
Message-ID: <20160413140900.5c490659@pallas.home.time-travellers.org>
In-Reply-To: <CAAF6GDdG3yU+VSyF+jXaX4eXs_5R+5Q2-pSY-mU4wiSP_+gXqw@mail.gmail.com>
References: <5703F0CF.3050306@gmail.com> <87egaidh3y.fsf@alice.fifthhorseman.net> <CAAF6GDcwGJmrPcFj_o+tCe7PTL5jFj=YZ+2LCgCTVZ=64CpOdA@mail.gmail.com> <87vb3rm7d9.fsf@alice.fifthhorseman.net> <CAAF6GDfp9X0=P1j0xPBsSniHWNEi7Vu=xwR71GGbwJ9jbQkeGA@mail.gmail.com> <20160411145244.1f111f43@pallas.home.time-travellers.org> <20160411175401.GA27230@mycre.ws> <CAAF6GDdG3yU+VSyF+jXaX4eXs_5R+5Q2-pSY-mU4wiSP_+gXqw@mail.gmail.com>
X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu)
MIME-Version: 1.0
Content-Type: multipart/signed; micalg="pgp-sha1"; boundary="Sig_/iC4ye5ywNtfKRp/AWK8KihF"; protocol="application/pgp-signature"
Archived-At: <http://mailarchive.ietf.org/arch/msg/dns-privacy/MoJeAa6Ux1sBpARtoUZ_1OQZKhs>
Cc: "dns-privacy@ietf.org" <dns-privacy@ietf.org>
Subject: Re: [dns-privacy] DNS + 0-RTT
X-BeenThere: dns-privacy@ietf.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: <dns-privacy.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/dns-privacy>, <mailto:dns-privacy-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/dns-privacy/>
List-Post: <mailto:dns-privacy@ietf.org>
List-Help: <mailto:dns-privacy-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/dns-privacy>, <mailto:dns-privacy-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 13 Apr 2016 12:09:07 -0000

Colm,

At 2016-04-11 10:59:02 -0700
Colm MacCárthaigh <colm@allcosts.net> wrote:

> On Mon, Apr 11, 2016 at 10:54 AM, Robert Edmonds <edmonds@mycre.ws> wrote:
> 
> > Unbound actually does support both fixed and randomized, and the entropy
> > is taken from an interesting place: the ID field from the query.
> 
> I think if there are more than 8 RRs, that won't be enough entropy to
> generate all possible permutations.

At first I thought this was shocking. SHOCKING.

But if the goal is merely to mix up the answers a bit so that software
that uses the first RR does not always get the same answer, then it is
Good Enough(tm). Even with a fully-predictable QID this is fine.

It's only when you consider the order of the RR private that this
becomes a concern.

I admit I don't fully understand how information leakage is supposed to
happen. But if it is a valid concern then probably a cryptographically
secure random number generation is needed, and needs to be documented.

Cheers,

--
Shane

v2.23.0 | Report a Bug | By Email