Re: [Acme] I-D Action: draft-ietf-acme-email-smime-06.txt

"A. Schulze" <sca@andreasschulze.de> Sun, 03 November 2019 11:03 UTC

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Subject: Re: [Acme] I-D Action: draft-ietf-acme-email-smime-06.txt
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Am 01.11.19 um 19:24 schrieb internet-drafts@ietf.org:
>       Title           : Extensions to Automatic Certificate Management Environment for end user S/MIME certificates
>       Author          : Alexey Melnikov
> 	Filename        : draft-ietf-acme-email-smime-06.txt
> 	Pages           : 10
> 	Date            : 2019-11-01

Hello,

I'v noticed this version enhance the number of header fields MUST be covered by DKIM.
But some of us may be are aware of "Breaking DKIM - on Purpose and by Chance" [1] published in 2017.

To mitigate such attacks it would be helpful to REQUIRE header fields also can't be added.
see https://tools.ietf.org/html/rfc6376#section-3.5, definition of h= and
INFORMATIVE EXPLANATION + NOTE

Andreas

[1] https://noxxi.de/research/breaking-dkim-on-purpose-and-by-chance.html