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Re: [dmarc-ietf] indeterminisim of ARC-Seal b= value

"John Levine" <johnl@taugh.com> Fri, 24 March 2017 21:23 UTC

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Date: Fri, 24 Mar 2017 21:23:04 -0000
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From: John Levine <johnl@taugh.com>
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Subject: Re: [dmarc-ietf] indeterminisim of ARC-Seal b= value
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In article <CANtLugO_D1Mz_v_341pc5O1mZ7RhOTrFA3+Ob5-onp72+5uRfA@mail.gmail.com> you write:
>The issue is that its possible for two separate arc implementations, given
>the exact same message inputs, keys, timestamps, etc to be generating two
>different, but equally valid ARC seal hashes.

DKIM does the same thing.  The order of fields in a DKIM-Signature
header is arbitrary, and the b= hash includes that header, so there
are lots of different equivalent DKIM signatures for the same message
and same selector and key.  Verifiers use the DKIM-Signature header in
the message so they get the same answer as the signer, which I would
think would work the same way in ARC-Seal.

Can you explain why you think this is a problem?

R's,
John

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