Re: [apps-discuss] Malformed mail guidance document (draft-ietf-appsawg-malformed-mail)

Alessandro Vesely <vesely@tana.it> Tue, 06 March 2012 15:12 UTC

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Date: Tue, 06 Mar 2012 16:12:35 +0100
From: Alessandro Vesely <vesely@tana.it>
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Subject: Re: [apps-discuss] Malformed mail guidance document (draft-ietf-appsawg-malformed-mail)
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On 06/Mar/12 09:04, Ned Freed wrote:
> 
>> Hm... MIME doesn't seem to say that either is better than the
>> other. Based on what you write below, I'd derive that token is
>> better than quoted-string, provided that quotes are actually
>> superfluous.  Hence, the I-D could state that that's the
>> canonical syntax, implying that DKIM signers (and verifiers) may
>> get smoother if they convert that way before playing their
>> magic.
> 
> I'm unclear as to the relevance. If you're transforming MIME
> content in some way - and if you're not why are you bothering to
> mess around with the headers - the content will be altered and any
> DKIM signature is going to be invalidated no matter what you do to
> the quotes.

Not necessarily.  The message you replied to was sent to apps-discuss
with Content-Type: text/plain; charset=us-ascii, but I received it
from mail.ietf.org with Content-Type: text/plain; charset="us-ascii".
Thus, the message was rewritten, and its signature would have been
broken if the Content-Type field had been signed (which should be the
behavior of choice, according to RFCs 6376-6377.)

As for the relevance, I admit it's a statistically irrelevant corner
case, which looks more like a DKIM shortcoming than a MIME fault.

> I don't see a problem with saying that, but a document that says
> that and that alone doesn't seem worth it to me. I'm also dubious
> that anything would change significantly because of making such a
> recommendation.

Yet, the less MIME rewriting, the more DKIM deployment is possible.