IETF Logo Mail Archive

Re: [dmarc-ietf] ARC questions

Michael Thomas <mike@mtcc.com> Sun, 22 November 2020 19:29 UTC

Return-Path: <mike@fresheez.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 8AFAD3A0B15 for <dmarc@ietfa.amsl.com>; Sun, 22 Nov 2020 11:29:30 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: 0.248
X-Spam-Level:
X-Spam-Status: No, score=0.248 tagged_above=-999 required=5 tests=[DKIM_SIGNED=0.1, DKIM_VALID=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.249, NICE_REPLY_A=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=no autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=mtcc-com.20150623.gappssmtp.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 Ej8XFygKoDjA for <dmarc@ietfa.amsl.com>; Sun, 22 Nov 2020 11:29:29 -0800 (PST)
Received: from mail-pf1-x429.google.com (mail-pf1-x429.google.com [IPv6:2607:f8b0:4864:20::429]) (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 76DAE3A0B12 for <dmarc@ietf.org>; Sun, 22 Nov 2020 11:29:29 -0800 (PST)
Received: by mail-pf1-x429.google.com with SMTP id n137so2813999pfd.3 for <dmarc@ietf.org>; Sun, 22 Nov 2020 11:29:29 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mtcc-com.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=LlIzTFLCLL5iIuRhglkyjtbOO96RK/WjRKn5xG292KM=; b=WKcmMLSbrevVDxvSYwQd+vVcP5MQpFr7FuDnQm/7aXa6E0pp2X97MQAl81DnM/NMOH 5n/aBASVrxJ/uL5XX1xcnQYAcde08r5ty4EhAWFKP4dN4oRkHipkB8eqUOVVq/rwTbCV k3wCsxQabKMsrTsupFQRZswv601OqpeYXeht49waON09hjnQoJpADSrWDBZAtIzkOnYx ki530KRNE3rlOTA76k9//zt+Xt2FMLWueJ+m1l4MANPY0y1DqTDf4UE6/w1VWa2ZWXVk 1gancJtpV4iaXvsh456GxAcdwP4EocyvAupx+JFDtsvlam0c0kiNcNU6U8pF4vI4Adr2 zypA==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=LlIzTFLCLL5iIuRhglkyjtbOO96RK/WjRKn5xG292KM=; b=ELlOsZLF5kW1fDRwk8wS2xu6DXJ/GnMR3W87Japyao2fw//MxkBZwJoulV0Cbe89pd s10UB75+WWN/0PRJDGfqdvDGbcv+M/N9OHjLLqQHY8rhw6dg8EAyDpxIqdrk32cUHeHf xtMyAxNRPBVc6SSTXEy01xR3nIh2xO51A4P9C/WwXPt4x1FJrBPQxhWc5kcC48vEEHTF 1hexSk9LYFTGlG60OT1OJuEVnQLCNRwhHJHFj6TNxqw3m5EDaee4NEe699PqfZ6gBF03 yzpqUzlj+xq15Gs9kn9yc52AZOfmiqW8XT9bWq/IwDkZnUT3HcnBgZVqhLPGHkbZ3M9J pdEQ==
X-Gm-Message-State: AOAM530xl5wQVnhAG7KTPpAGvK0USFRt/SoW+9PMR4IJ1HmygHPVLMPG +uyv3OncIr5ISKNiNDgGR4JpQnQOPS3efg==
X-Google-Smtp-Source: ABdhPJz4gRFR9omcfq8JDA/LtBKjW7eGde80d5Hi3yaymZlpTs36iGty/MfMf6jhILQgWxe1FGrtEg==
X-Received: by 2002:a63:3845:: with SMTP id h5mr23119183pgn.405.1606073368505; Sun, 22 Nov 2020 11:29:28 -0800 (PST)
Received: from mike-mac.lan (107-182-37-5.volcanocom.com. [107.182.37.5]) by smtp.gmail.com with ESMTPSA id v7sm9489067pfu.39.2020.11.22.11.29.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 22 Nov 2020 11:29:27 -0800 (PST)
To: John R Levine <johnl@taugh.com>, "Kurt Andersen (b)" <kboth@drkurt.com>
Cc: "dmarc@ietf.org" <dmarc@ietf.org>
References: <dcc265f9-a143-5093-eba0-94ee059c7cc7@mtcc.com> <20201122021417.B5E6E27B3E59@ary.qy> <CABuGu1pX=5ZC4RLsv19qrosRN9nCrPdeSk5Xg4O7ViEZit6dnA@mail.gmail.com> <453c4db4-fc62-dc76-5b15-707623d66f9f@mtcc.com> <64f18b-ae8-8c15-3d33-ff2d864c35bc@taugh.com>
From: Michael Thomas <mike@mtcc.com>
Message-ID: <884541e6-5076-7f8f-d1d2-d68ea9c5a2bc@mtcc.com>
Date: Sun, 22 Nov 2020 11:29:26 -0800
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.12.1
MIME-Version: 1.0
In-Reply-To: <64f18b-ae8-8c15-3d33-ff2d864c35bc@taugh.com>
Content-Type: text/plain; charset="utf-8"; format="flowed"
Content-Transfer-Encoding: 8bit
Content-Language: en-US
Archived-At: <https://mailarchive.ietf.org/arch/msg/dmarc/XfMPvlMs2Hld2_BvoJjP-oWPkv8>
Subject: Re: [dmarc-ietf] ARC questions
X-BeenThere: dmarc@ietf.org
X-Mailman-Version: 2.1.29
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: Sun, 22 Nov 2020 19:29:31 -0000

On 11/22/20 11:14 AM, John R Levine wrote:
>> Is there a reason that there is a separate ARC-signature rather than 
>> just using the DKIM signature that is normally created for the new 
>> message? Since ARC is new, you'd not want the intermediary to stop 
>> DKIM signing the message so you end up with essentially two 
>> signatures doing essentially the same thing?
>
> The ARC signature has a sequence number so you can track the chain of 
> custody.  You are right that it is similar to the DKIM signature but 
> the extra ovehead doesn't seem excessive.
>
Did the wg consider just grafting that onto the DKIM signature itself 
instead of having essentially a duplicate signature? Receivers are 
already supposed to ignore any tags they don't understand so it 
shouldn't hurt backward compatibility.

Mike

v2.23.0 | Report a Bug | By Email