Re: [dmarc-ietf] Alternative draft text for draft-ietf-dmarc-arc-protocol
Seth Blank <seth@valimail.com> Wed, 10 May 2017 00:40 UTC
Return-Path: <seth@valimail.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 6627A129553 for <dmarc@ietfa.amsl.com>; Tue, 9 May 2017 17:40:10 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.699
X-Spam-Level:
X-Spam-Status: No, score=-2.699 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=valimail.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 Tsh4Wjp6ksxB for <dmarc@ietfa.amsl.com>; Tue, 9 May 2017 17:40:07 -0700 (PDT)
Received: from mail-qk0-x22f.google.com (mail-qk0-x22f.google.com [IPv6:2607:f8b0:400d:c09::22f]) (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 D99E7124217 for <dmarc@ietf.org>; Tue, 9 May 2017 17:40:06 -0700 (PDT)
Received: by mail-qk0-x22f.google.com with SMTP id y201so15747054qka.0 for <dmarc@ietf.org>; Tue, 09 May 2017 17:40:06 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=valimail.com; s=google2048; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=XUj/SFKixI5el8ZjS1zefJsECdNU0Ie667uXxZOxgFM=; b=I3NW92T2dDeu7NAicsjYCeAFLQ9n78vn/cMYY8Gyh1Avp1DuNInnRQoK4dZf9VaVEI RFwxoHX8T5KXAUx/t6W5djmK8rkl9D4G2NS6NKURxj0x+F76xsn4A8TDxWEont21Ni89 nqbgD4bUgC6ZhQ++tWhdUYdTvdLfz6Ff6PhH0JaKS9J3JgnzdMpk+I6k6ii8e8P4aDcW 8/3YyAOsZgzqZATh2bx817Y0msc5hTn42q86RydtV1JsRRKg9P+ly+oIYU0mN8D5SrWQ BCONJqGR/jMSXDljqOGE+SMjDKtYXTSxYleWOxwZYdDNQ9vwR2U1kMPgVKLDn/RGcYGz StAg==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=XUj/SFKixI5el8ZjS1zefJsECdNU0Ie667uXxZOxgFM=; b=mVrGdUbjrN5KIRXHRfSQ3ZR3yRfDc3DImdIUMQ6mYor7CVOXXz0VbTLDGoh0tlA00K FVmvizH89cuvSXhasCcC63Wb+hTsxXusDxTYEJbUPdDi+NH4yGJZdMN0j9Bajvp2OwIR p5YRuNxgY6V1exPl+nQIUYztbhLU9QHz8P4SwXso8MttCQCv3UoXleIh8qe4Qq2eACtd +p7Nuy8/kw8zZSQgNRxNdtd2yjbv88WzpIRj5IUTjbT+Od14GxbwvRyXDDsKtcm8S3ZU 7c6y2K6WuA383WYdRDtu0TpIBu6HlrDFUw6sF+4y9HGIhgKKiFgvk/gBDbk6h99qOPtm KytQ==
X-Gm-Message-State: AODbwcDIWNz/TLMtIYGd6GN4zU/Fro88v8l/PQkKl8gOxOnRkjgRfbjP lQjOTdFWMPH7z/zhcaoGW1UDsj2vTQ==
X-Received: by 10.55.134.131 with SMTP id i125mr2893625qkd.17.1494376805931; Tue, 09 May 2017 17:40:05 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.200.42.120 with HTTP; Tue, 9 May 2017 17:39:45 -0700 (PDT)
In-Reply-To: <CANtLugMJV9_SOp0tSnjODmo7viiChk5NupVq5+7od_4scQ2iJg@mail.gmail.com>
References: <CAL0qLwZEeL8ksPK3AwXjty1+RRUgAH=kL1MUOwERGiGxOGd5NQ@mail.gmail.com> <CABa8R6vL720q879ks7ELPBH6aXjigntmHQ65hy86T-MQvLJ6+g@mail.gmail.com> <CANtLugMJV9_SOp0tSnjODmo7viiChk5NupVq5+7od_4scQ2iJg@mail.gmail.com>
From: Seth Blank <seth@valimail.com>
Date: Tue, 09 May 2017 17:39:45 -0700
Message-ID: <CAOZAAfPBiHYnMfzgs-HDWuQxvTfzdavHuYWRn94SvQG8+3FpFw@mail.gmail.com>
To: "dmarc@ietf.org" <dmarc@ietf.org>
Cc: Brandon Long <blong@google.com>, "Murray S. Kucherawy" <superuser@gmail.com>, Gene Shuman <gene@valimail.com>
Content-Type: multipart/alternative; boundary="94eb2c07019aadb6e4054f20b6d8"
Archived-At: <https://mailarchive.ietf.org/arch/msg/dmarc/ILeNJz3MenttsY0Ws6t2Z_IW31k>
Subject: Re: [dmarc-ietf] Alternative draft text for draft-ietf-dmarc-arc-protocol
X-BeenThere: dmarc@ietf.org
X-Mailman-Version: 2.1.22
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: Wed, 10 May 2017 00:40:10 -0000
I've got two follow ups from Gene's notes on the proposed draft: 1. I am also confused by section 5.2, specifically the penultimate sentence in the section. I think - but am not certain - that I understand what is meant. I've suggested new language below to clarify. Original: "Of particular importance is the recording of the "i=2" instance of this field, which is the first available opportunity in the handling chain of the message to evaluate its apparent validity since departing its originating ADMD." Suggested: "Of particular importance is the first AAR header after an ARC signed message leaves its originating ADMD, which is generally but not always the "i=1" instance of this field. This instance contains the authentication information of first receipt which the ARC chain is establishing custody of to a final receiver." 2. Also, in section 9.5, an IANA Consideration for "temperror" is defined but I think this was supposed to be for "invalid". Seth On Tue, May 9, 2017 at 3:56 PM, Gene Shuman <gene@valimail.com> wrote: > I've taken a look at the proposed draft and have a few notes as well. > > 4. The currently specified limits on i= are not included MUST >10, SHOULD > > 50, etc > > 5.1 - In the current draft, it's mandated that AMS must use relaxed header > canonicalization, but that's missing from the proposed draft > > 5.2 - I'm a bit confused by the comment noting the importance of i=2. > What is it that you're intending there? > > 5.3.1 - typo: one of three possible values: -> one of *four* possible > values > > 7.2 - It may be worth elaborating more on the possible ways in which > cv=invalid can arise, if not here, maybe somewhere else > > 7.4 - In general I prefer this to the psuedo code in the current draft, > but I think it could still use a bit of work. In particular, sections C-H > are exactly describing how to validate a DKIM signature and seems somewhat > unnecessary. Is there any particular reason you decided to include this, as > opposed to just relying on the DKIM spec for this? > > 7.5 - typo: no -> all > > In general though, I agree with Brandon, the proposed draft definitely > makes some things clearer, which I think is a step in the right direction. > > =Gene > > > On Tue, May 9, 2017 at 2:04 PM, Brandon Long <blong@google.com> wrote: > >> In 5.1 defining the AMS, you say that it should cover DKIM-Signature and >> AuthRes headers. In particular, AuthRes headers are expected to be removed >> by ADMDs, especially if the message transits the same ADMD multiple times. >> Also, the information in the AuthRes header is superseded by the ArcAuthRes >> header. Including it means an arbitrary AMS breakage for something pretty >> minor, so I would recommend to not include it. >> >> Our implementation explicitly blacklists that header. >> >> I know some mailing lists also strip the DKIM-Signature header, but since >> they are likely to break the AMS anyways, that's less important. I'm not >> sure what the benefit is to including it, but it seems harmless. In >> particular, if the DKIM-Signature still passes, then the ARC isn't adding >> that much, and removing the DKIM-Signature header doesn't mean all that >> much either since it's validity was already assessed and that assessment >> included in the AAR. We don't blacklist the DKIM-Signature method in our >> implementation, but I don't understand the advisement. >> >> You also talk about "responsibility". I'm not sure that's how I would >> describe it. An ARC hop is documenting that a message passed through it, >> and that it evaluated the authentication of the message. The only >> responsibility of a hop is to correctly validate the SPF/DKIM/ARC >> information, there is no ownership implied over the message itself. >> >> With AMS, you can answer the question: which ADMD is the last ADMD to >> have modified the message. I guess in that sense, the last modifier is >> "responsible" for the current state of the message... but that kind of >> means that the AMS of previous hops allows them to disown responsibility >> for the current state of the message... >> >> 5.2 - should we point out that there should be only one of these per >> hop? The openspf/dkim/dmarc implementations tend to add separate AuthRes >> headers for each evaluation, but ARC requires those to be a single instance. >> >> 5.3.1 - none as defined as "arrives at an MTA from an MSA", perhaps my >> understanding of those terms is slightly odd, but I would think that an MSA >> usually uses an MTA to actually send the message, and it isn't that >> "sending" MTA that's the first hop, it should be the first "receiving" >> MTA. I mean, that's usually the point at which the DKIM signature is >> applied, and the SPF would be "from" there, not based on the location of >> the MUA. >> >> There are some missing pieces here, corresponding to the current draft >> sections 5.4 (alternate signing algorithms), 6.4.3 (arc email >> authentication method for AuthRes), 6.4.5 for dmarc xml. I see that the >> arc is included in your IANA section, not sure if the call out outside of >> the definition is necessary or not. >> >> Overall, I think your draft makes some things clearer, and some things in >> the original are clearer. It's worth looking into either combining or >> choosing. >> >> >> Brandon >> >> On Thu, May 4, 2017 at 12:56 AM, Murray S. Kucherawy <superuser@gmail.com >> > wrote: >> >>> Colleagues, >>> >>> As I progress (slowly, alas) toward completing my sample implementation >>> of OpenARC, I've found myself taking a lot of notes about the current >>> draft. This has helped me make progress; in some cases it became things I >>> posted to the list, and in others it was just to help or confirm my >>> understanding of the protocol. >>> >>> I have developed this enough to become a fairly comprehensive >>> alternative text to the current draft. I find the layout of this version >>> to flow better for my own purposes, and in a few places I've tried to >>> clarify some of the material by rewriting chunks of it. None of this is >>> meant to assert that the current draft is deficient; I've just found it to >>> be a helpful exercise for me. >>> >>> I offer it here to the WG as a contribution; the WG of course is free to >>> use some, all, or none of it as it wishes. >>> >>> http://blackops.org/~msk/draft-kucherawy-dmarc-arc-base.txt >>> >>> If it would be more helpful to post this as an I-D, please let me know. >>> >>> -MSK >>> >>> _______________________________________________ >>> dmarc mailing list >>> dmarc@ietf.org >>> https://www.ietf.org/mailman/listinfo/dmarc >>> >>> >> >> _______________________________________________ >> dmarc mailing list >> dmarc@ietf.org >> https://www.ietf.org/mailman/listinfo/dmarc >> >> > > _______________________________________________ > dmarc mailing list > dmarc@ietf.org > https://www.ietf.org/mailman/listinfo/dmarc > > -- [image: logo for sig file.png] Bringing Trust to Email Seth Blank | Head of Product for Open Source and Protocols seth@valimail.com +1-415-894-2724 <415-894-2724>
- [dmarc-ietf] Alternative draft text for draft-iet… Murray S. Kucherawy
- Re: [dmarc-ietf] Alternative draft text for draft… Seth Blank
- Re: [dmarc-ietf] Alternative draft text for draft… Brandon Long
- Re: [dmarc-ietf] Alternative draft text for draft… Gene Shuman
- Re: [dmarc-ietf] Alternative draft text for draft… Seth Blank
- Re: [dmarc-ietf] Alternative draft text for draft… Brandon Long
- Re: [dmarc-ietf] Alternative draft text for draft… Seth Blank
- Re: [dmarc-ietf] Alternative draft text for draft… Murray S. Kucherawy
- Re: [dmarc-ietf] Alternative draft text for draft… Murray S. Kucherawy
- Re: [dmarc-ietf] Alternative draft text for draft… Murray S. Kucherawy