Re: [dmarc-ietf] ARC questions

Michael Thomas <mike@mtcc.com> Wed, 02 December 2020 20:32 UTC

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To: John R Levine <johnl@taugh.com>, Brandon Long <blong@google.com>
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From: Michael Thomas <mike@mtcc.com>
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Date: Wed, 2 Dec 2020 12:32:34 -0800
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Subject: Re: [dmarc-ietf] ARC questions
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On 12/2/20 12:31 PM, John R Levine wrote:
> On Wed, 2 Dec 2020, Michael Thomas wrote:
>>> Ignoring the existing usage of DKIM, DKIM+A-R would only work for a 
>>> single hop, and lead to some complication compared to the other DKIM 
>>> signatures already on the message.
>>
>> Wait, what? a DKIM signatures survives until it encounters an 
>> intermediary that alters the message in a breaking manner. 
>> Arc-Signatures are no different in that respect. In fact as far as I 
>> can tell they are identical modulo the i= difference.
>
> Please reread the ARC spec.  The ARC-Authentication-Results at level N 
> tells you whether the ARC and DKIM signatures were good at level N-1.
>

That's why I said "modulo the i= difference"

Mike