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Re: [dmarc-ietf] Response to a claim in draft-crocker-dmarc-author-00 security considerations

Dave Crocker <dhc@dcrocker.net> Sun, 26 July 2020 13:50 UTC

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To: Brandon Long <blong@google.com>
Cc: Dotzero <dotzero@gmail.com>, IETF DMARC WG <dmarc@ietf.org>
References: <bf5b68c74a3c487ca8a07a0a27061e47@com> <87zh7ur069.fsf@orion.amorsen.dk> <3829fac4748a48d0b752403450843bd5@bayviewphysicians.com> <c9353a06-ab31-c397-449e-7d36afbf655d@wisc.edu> <c2ad22cd-8b35-733f-bc4c-839e2c4b3e98@dcrocker.net> <CAJ4XoYf23gu4m7Zru2iq9SV-hYNCx6KFg4J7oTDpLpTcXFk7Rg@mail.gmail.com> <f2cd4931-9f61-2031-00bc-af9c460c15a3@bbiw.net> <CAJ4XoYf=XhaHKZpUjwoBJnLMwq_0LajTBWjJ01qjCaP7365E=w@mail.gmail.com> <2f231818-5c25-eca3-9db6-3af0fba7d5c8@gmail.com> <CABa8R6t7Wsm88_qZ3k9w80xinNFoEtj3voY3y0ow=9+3csZofQ@mail.gmail.com>
Reply-To: dcrocker@bbiw.net
From: Dave Crocker <dhc@dcrocker.net>
Organization: Brandenburg InternetWorking
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Date: Sun, 26 Jul 2020 06:49:51 -0700
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Subject: Re: [dmarc-ietf] Response to a claim in draft-crocker-dmarc-author-00 security considerations
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On 7/21/2020 1:42 PM, Brandon Long wrote:
> Stricter validation is not an uncommon addition to protocols over the 
> last 45 years.


If there are examples of adding stricter validation in a way that 
essentially requires changing the semantics of the payload, in order for 
the payload to survive, I can't think of any. Not TLS, not DNSSec, not 
S/MIME or PGP.

DMARC essentially enforces a semantic on the From: field as a handling 
identifier, rather than an author identifier.

When activity that has a long history of semantic validity and a 
continued desire for operation is forced to break the denotational 
source of authoring information, in order to get the mail delivered, 
then we are in new territory.

d/

-- 
Dave Crocker
Brandenburg InternetWorking
bbiw.net

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