IETF Logo Mail Archive

Re: [dmarc-ietf] WGLC ARC-16 concern on Section 5.1.2 - cv=fail should sign greedily

"John R Levine" <johnl@taugh.com> Fri, 03 August 2018 17:54 UTC

Return-Path: <johnl@taugh.com>
X-Original-To: dmarc@ietfa.amsl.com
Delivered-To: dmarc@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 4AB62131084 for <dmarc@ietfa.amsl.com>; Fri, 3 Aug 2018 10:54:05 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.901
X-Spam-Level:
X-Spam-Status: No, score=-1.901 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, 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 H4srms1akhsl for <dmarc@ietfa.amsl.com>; Fri, 3 Aug 2018 10:54:03 -0700 (PDT)
Received: from gal.iecc.com (gal.iecc.com [IPv6:2001:470:1f07:1126:0:43:6f73:7461]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 536DA131088 for <dmarc@ietf.org>; Fri, 3 Aug 2018 10:54:03 -0700 (PDT)
Received: (qmail 83355 invoked from network); 3 Aug 2018 17:54:02 -0000
Received: from localhost ([IPv6:2001:470:1f07:1126::78:696d:6170]) by imap.iecc.com ([IPv6:2001:470:1f07:1126::78:696d:6170]) with ESMTPS (TLS1.2/X.509/AEAD) via TCP6; 03 Aug 2018 17:54:02 -0000
Date: Fri, 03 Aug 2018 13:54:01 -0400
Message-ID: <alpine.OSX.2.21.1808031352460.29088@ary.qy>
From: John R Levine <johnl@taugh.com>
To: Brandon Long <blong@google.com>
Cc: dmarc@ietf.org
In-Reply-To: <CABa8R6sWSu9Q+mozxzaVGab3PE2zxqVmt4L6FERSLC1oDTh1oA@mail.gmail.com>
References: <CAD2i3WNSe+of7U8fdTnmUeU3sthUbpEVgdYHT9J6BgLxoeOL3w@mail.gmail.com> <20180730221726.713CE200316625@ary.qy> <CAD2i3WMvCugRm4KZeLx3PFb6f_pKR3rs4mnH2FZO4_X7ZA7GHA@mail.gmail.com> <alpine.OSX.2.21.1807302025420.60501@ary.qy> <CABa8R6sWSu9Q+mozxzaVGab3PE2zxqVmt4L6FERSLC1oDTh1oA@mail.gmail.com>
User-Agent: Alpine 2.21 (OSX 202 2017-01-01)
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"; format="flowed"
Archived-At: <https://mailarchive.ietf.org/arch/msg/dmarc/MEUiLNIvmgfo12lOX3_Arr1nVa8>
Subject: Re: [dmarc-ietf] WGLC ARC-16 concern on Section 5.1.2 - cv=fail should sign greedily
X-BeenThere: dmarc@ietf.org
X-Mailman-Version: 2.1.27
Precedence: list
List-Id: "Domain-based Message Authentication, Reporting, and Compliance \(DMARC\)" <dmarc.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/dmarc>, <mailto:dmarc-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/dmarc/>
List-Post: <mailto:dmarc@ietf.org>
List-Help: <mailto:dmarc-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/dmarc>, <mailto:dmarc-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 03 Aug 2018 17:54:05 -0000

> I know I lost the argument on cv (I think cv is entirely superfluous and
> there's no point adding/signing a cv=fail header), but it seems the
> argument for that is more data.  That said, this "either or" signing set
> thing on cv=fail seems pretty cumbersome.

You guys have looked at as many ARC signatures as anyone.  Once the chain 
has a cv=fail do you learn anything useful from further seals?

R's,
John

>> In 5.2, oldest pass is confusing, since it doesn't tell you whether
>> the validation succeeds or not.  I would take out steps 5-7 and add
>> something to the INFORMATIONAL at the end like "A validator can check
>> the AMS headers to estimate when in a chain of forwards the message
>> was modified."

v2.23.0 | Report a Bug | By Email