Re: [dane] email canonicalization for SMIMEA owner names

Nico Williams <nico@cryptonector.com> Fri, 12 December 2014 16:21 UTC

Return-Path: <nico@cryptonector.com>
X-Original-To: dane@ietfa.amsl.com
Delivered-To: dane@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id D6D821A1B56 for <dane@ietfa.amsl.com>; Fri, 12 Dec 2014 08:21:11 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.666
X-Spam-Level:
X-Spam-Status: No, score=-1.666 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, IP_NOT_FRIENDLY=0.334, RCVD_IN_DNSWL_NONE=-0.0001] autolearn=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 fNMrreG0aOKq for <dane@ietfa.amsl.com>; Fri, 12 Dec 2014 08:21:11 -0800 (PST)
Received: from homiemail-a63.g.dreamhost.com (sub4.mail.dreamhost.com [69.163.253.135]) by ietfa.amsl.com (Postfix) with ESMTP id 2BC061A1AF4 for <dane@ietf.org>; Fri, 12 Dec 2014 08:21:11 -0800 (PST)
Received: from homiemail-a63.g.dreamhost.com (localhost [127.0.0.1]) by homiemail-a63.g.dreamhost.com (Postfix) with ESMTP id E2AEA2F406A; Fri, 12 Dec 2014 08:21:10 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=cryptonector.com; h=date :from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to; s=cryptonector.com; bh=XvkRsubvPorV4A Re3Qm9UdvEXmQ=; b=s8OsgnkHYzmHUUmDrCpmVwjVecs4XySweltCM6mxQiS7dI /L/ZL1YVwwcQm+8JS0XDkJQ0TdPDVI7sOqJFADXCsxPmcvSX7MJYZBanpGy19Xk5 PiorIu7qs2kMKwC1KNuJV//SZWLFNKtOlzWNBPOVGn/ib8mNrKyG/R6LGSjao=
Received: from localhost (108-207-244-174.lightspeed.austtx.sbcglobal.net [108.207.244.174]) (Authenticated sender: nico@cryptonector.com) by homiemail-a63.g.dreamhost.com (Postfix) with ESMTPA id 8CBE72F4057; Fri, 12 Dec 2014 08:21:10 -0800 (PST)
Date: Fri, 12 Dec 2014 10:21:09 -0600
From: Nico Williams <nico@cryptonector.com>
To: Paul Wouters <paul@nohats.ca>
Message-ID: <20141212162104.GU3448@localhost>
References: <20141212043208.11432.qmail@ary.lan> <20141212044212.318552553F6A@rock.dv.isc.org> <20141212050826.GT3448@localhost> <alpine.LFD.2.10.1412121111120.31305@bofh.nohats.ca>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <alpine.LFD.2.10.1412121111120.31305@bofh.nohats.ca>
User-Agent: Mutt/1.5.21 (2010-09-15)
Archived-At: http://mailarchive.ietf.org/arch/msg/dane/TN7Cn4_gAb7Xw5SsQbwSt12bbPg
Cc: dane WG list <dane@ietf.org>
Subject: Re: [dane] email canonicalization for SMIMEA owner names
X-BeenThere: dane@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: DNS-based Authentication of Named Entities <dane.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/dane>, <mailto:dane-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/dane/>
List-Post: <mailto:dane@ietf.org>
List-Help: <mailto:dane-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/dane>, <mailto:dane-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 12 Dec 2014 16:21:12 -0000

On Fri, Dec 12, 2014 at 11:12:56AM -0500, Paul Wouters wrote:
> On Thu, 11 Dec 2014, Nico Williams wrote:
> >Yes: use MSA/MTA as the keyserver, both for lookup and registration.
> 
> Why add another service, another dependancy and another choke point and
> another trans protocol for auditing that the world sees the same view?

Well, it's another service on a protocol that already exists, that the
MUA must speak, and has similar functionality (VRFY) anyways.

> That can all be done with DNS.

If done *only* with DNS then we get into the canonicalization/zone
walking (spam) trap and we then have to do something that sucks.

> Adding another service just adds more problems.

So does not adding it.  It's a case of pick your poison.

I can't say I like one poison better than the other yet...


BTW, for the DNS-only scheme, there's no need for local-part canon when
verifying sender certs: because hopefully! the sender's MUA will use a canonical
sender local-part.

As for looking up a recipient's encryption cert...  well, if the MUA
gets the wrong recipient local-part form as a result of applying an
incorrect canonicalization, then it could get the wrong recipient -- a
relatively minor problem, but one worth noting.

The SMIMEA I-D does need to describe the motions that the MUA goes
through to do the two different tasks: verifying sender signature certs,
and finding recipient encryption certs.

Nico
--