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

Ned Freed <ned.freed@mrochek.com> Thu, 08 March 2012 02:40 UTC

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Date: Wed, 07 Mar 2012 18:35:52 -0800
From: Ned Freed <ned.freed@mrochek.com>
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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.)

But that only supports my argument - the list also adds a footer to the
message, invalidating any signature on the message body. Who cares about the
quotes on a header field when the body was altered?

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

Well, I offered to work on the MIME canonicalization problem for DKIM, which
happens to be a problem I've given a lot of thought to. Nobody showed even the
slightest interest, so...

				Ned