ietf-dkim
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Re: [ietf-dkim] THIS IS A MULTIPLE 5322.FROM MESSAGE

2010-10-06 12:59:43

Apologies all for top posting. Having to use a different client due to 
technical difficulties.

Murray, I'm violently agreeing with you that it is not strictly speaking a 4871 
issue. 

Having said that, I believe that it is an issue that begs the question... where 
should it land? You are correct that this is the difference between 
implementation and standards. Either way, we need to look at the outcomes of 
what we do.

I'm agreeing with you that IETF-DKIM may not be the place to address 
it...assuming there is a beleif that it is a problem at all. So the first 
question is whether this is a problem, if the consensus is that it isn't a 
problem, great...nothing more need be done.

If the consensus is that it is a problem but not really a 4871 problem then do 
we just walk away from it and leave it at that - "not our problem"? Should we 
perhaps look for the place where the 5322 people roost (I hear that working 
group shut down as part of IETF reorg) and at least say... "hey, this came up 
in the context of 4871 and we believe there may be some wider implications and 
it may be worth considering whether 5322 should be considered in light of this".

Mike

-----Original Message-----
From: ietf-dkim-bounces(_at_)mipassoc(_dot_)org on behalf of Murray S. Kucherawy
Sent: Wed 10/6/2010 8:13 AM
To: ietf-dkim(_at_)mipassoc(_dot_)org
Subject: Re: [ietf-dkim] THIS IS A MULTIPLE 5322.FROM MESSAGE
 
-----Original Message-----
From: MH Michael Hammer (5304) [mailto:MHammer(_at_)ag(_dot_)com]
Sent: Wednesday, October 06, 2010 12:20 AM
To: Murray S. Kucherawy; ietf-dkim(_at_)mipassoc(_dot_)org
Subject: RE: [ietf-dkim] THIS IS A MULTIPLE 5322.FROM MESSAGE

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.

I don't think that's a fair characterization.  It is simply wrong to try to 
deal this problem in DKIM.  For example, a bug in the TCP stack that causes 
malformed data to arrive in an application which in turn causes something 
visible and unexpected, possibly even something dangerous, to happen in that 
application is still a bug in the TCP stack and saying so puts the 
responsibility for resolving the problem where it belongs.

There's also a practical difference between software engineering and 
specification.  You'd be justified in deciding to make your MUA code resilient 
to this problem, but it's wrong for doing so to be mandated by a standards 
document that has nothing to do with defining the proper format of email.

I believe this is a good example of a layering violation.

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.

I understand that concern, but it sounds a lot to me like trying to ascribe a 
different value to the former case than the latter when we don't know that they 
deserve different handling.  (And that sounds a lot like the unresolved ADSP 
rathole.)

To me, there's a clear boundary between what DKIM defines and what RFC5322 
defines.  This problem isn't on our side of that line.  The RFC5322 part of the 
code in a verifier should detect and report that the message is malformed, and 
the DKIM part shouldn't even be invoked.


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