ietf-dkim
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Re: [ietf-dkim] 8bit downgrades

2011-05-20 00:36:10
-----Original Message-----
From: ietf-dkim-bounces(_at_)mipassoc(_dot_)org 
[mailto:ietf-dkim-bounces(_at_)mipassoc(_dot_)org] On Behalf Of Hector Santos
Sent: Thursday, May 19, 2011 8:38 PM
To: Pete Resnick
Cc: ietf-dkim(_at_)mipassoc(_dot_)org
Subject: Re: [ietf-dkim] 8bit downgrades

100%?  That is extreme.

...but correct.

    Such conversion is outside the scope of DKIM; the actual
    message SHOULD be converted to 7-bit MIME by an MUA or MSA
    prior to presentation to the DKIM

I read that (in the context of the paragraph containing it, of course) to mean 
the particular selection of a conversion method is out of scope for DKIM.  But 
that does not mean the issue of whether or not conversion is necessary or 
advisable is also out of scope.  If it's okay for us to discuss things like 
header field reordering and spacing changes that might affect validation of 
DKIM signatures, it certainly seems to me that this is a valid topic as well.

So I don't even know why we are talking about this.

The presented argument, which comes from an IETF outsider involved with MTA 
development, is whether or not that SHOULD is worthy of a MUST because failing 
to do it in the vast majority of cases will result in a downgrade somewhere on 
the path that will invalidate the signature.  The question, then, is why we 
didn't do MUST in the first place.  It's a perfectly legitimate question.

The answer is twofold: One, explain what SHOULD and MUST really mean, 
especially in context.  Two, list the options (downgrade and sign, don't 
downgrade and sign, don't sign) and the effects of each.

Providing a solid and helpful answer, rather than a dismissive or hostile one, 
promotes understanding from people that weren't involved, who are the ones that 
get to implement and deploy what we've specified.  That's certainly my 
preference.

-MSK

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