Re: [Dcrup] I-D Action: draft-ietf-dcrup-dkim-usage-02.txt

"Murray S. Kucherawy" <superuser@gmail.com> Tue, 13 June 2017 13:32 UTC

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From: "Murray S. Kucherawy" <superuser@gmail.com>
Date: Tue, 13 Jun 2017 06:32:08 -0700
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To: Martin Thomson <martin.thomson@gmail.com>
Cc: Scott Kitterman <sklist@kitterman.com>, dcrup@ietf.org
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Subject: Re: [Dcrup] I-D Action: draft-ietf-dcrup-dkim-usage-02.txt
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On Tue, Jun 13, 2017 at 3:52 AM, Martin Thomson <martin.thomson@gmail.com>
wrote:

> Oh, I see where you are coming from.  I think that you need text that
> says "an rsa-sha1 signature MUST be ignored by a verifier".  I think
> that answers the questions about "rely on" more clearly.
>

If we really need to say something like this, I'd prefer to drop the
MUSTard for previously given reasons.  Suggest something like:

"Since SHA1 is a deprecated hash algorithm generally, DKIM's 'rsa-sha1'
algorithm is as well (see [John's draft] which changes its status in the
IANA registry), and thus verifiers therefore ignore signatures that use
this algorithm."

-MSK