I've cogitated on this a bit and spoken with a few knowledgeable people.
I'm an operations guy and only marginally a standards wonk.
So, my belief is that this is really more of a 5322 issue than a 4871
issue. Having said that, I'm not comfortable kicking the can down the
road given that what we know, this potentially leads to abuse.
If the message is malformed and nonconforming then would it be
appropriate to treat the malformed message as no signature? This would
be one approach that appears consistent with 4871 yet this grinds on me
because it means we are saying that a malformed message with a signature
is the same as a conforming signature with no signature.
We also have to consider that verifier may be an MTA or an MUA. The
implications (operationally) are different for each case. It has also
been pointed out to me that a mail implementation may try to fix a
malformed message.
Regardless of my belief that this is a 5322 issue, my personal
preference would be for DKIM verifiers to not validate malformed
messages with an outcome of something along the lines of "unable to
validate due to malformed message". I view this as different than DKIM
none. This is perhaps more of an operations perspective.
Just a few poorly expressed thoughts and lacking a concrete
recommendation that is actionable.
Mike
-----Original Message-----
From: ietf-dkim-bounces(_at_)mipassoc(_dot_)org [mailto:ietf-dkim-
bounces(_at_)mipassoc(_dot_)org] On Behalf Of Murray S. Kucherawy
Sent: Wednesday, October 06, 2010 1:22 AM
To: ietf-dkim(_at_)mipassoc(_dot_)org
Subject: Re: [ietf-dkim] THIS IS A MULTIPLE 5322.FROM MESSAGE
-----Original Message-----
From: ietf-dkim-bounces(_at_)mipassoc(_dot_)org [mailto:ietf-dkim-
bounces(_at_)mipassoc(_dot_)org] On Behalf Of Mark Delany
Sent: Tuesday, October 05, 2010 8:06 PM
To: ietf-dkim(_at_)mipassoc(_dot_)org
Subject: Re: [ietf-dkim] THIS IS A MULTIPLE 5322.FROM MESSAGE
There was an assertion in RFC4780 about "conforming emails" that
must
only have a single 2822.From header. That got lost in the
translation
to 4781 I guess. Unfortunately, 4780 failed to specify what
"conforming" means explicitly.
I also know that this WG has repeatedly stated that messages that
are
not within standard MUST fail verification.
That this is not in 4871 seems to be mostly a WG assumption that
should be made explicit.
I think several of us thought it was in there, but on review it
apparently
was indeed lost somewhere along the way. We've certainly, as I
understand
it, been proceeding from that assumption for a very long time.
I like the idea of saying so explicitly in 4871bis, and applying it
both
to signers and to verifiers.
I don't like the idea of being any more specific than that. That is,
I
don't want to create specific text for specific cases we know about
because that means anything we don't list could be perceived as less
critical. A blanket admonishment to implementers is sufficient and
appropriate.
_______________________________________________
NOTE WELL: This list operates according to
http://mipassoc.org/dkim/ietf-list-rules.html
_______________________________________________
NOTE WELL: This list operates according to
http://mipassoc.org/dkim/ietf-list-rules.html