On 6/30/11 9:53 AM, Murray S. Kucherawy wrote:
-----Original Message-----
From: ietf-dkim-bounces(_at_)mipassoc(_dot_)org
[mailto:ietf-dkim-bounces(_at_)mipassoc(_dot_)org] On Behalf Of Charles
Lindsey
Sent: Thursday, June 30, 2011 7:05 AM
To: DKIM
Subject: Re: [ietf-dkim] Pete's review of 4871bis
The problem is that an apparently valid signature (albeit atching the
wrong From) is likely to give a false impression of validity somewhere
along the line unless modules down the line are watchig for this case (and
for sure MUAs will not be watching for it for a long time, so it is the
ISPs/boundary agents that need to do it).
If the advent of DKIM means that numerous modules implementing other
specifications loosely suddenly have to pay a price for doing so, then that's
the reality, and I still don't see how that's a problem DKIM needs to fix.
Sure, we need to document the nuances DKIM introduces, but it's still not an
attack against DKIM, so this remains the wrong place to deal with it in a
normative sense.
If you prefer the loose application of other standards, don't use DKIM (and
lose out on its benefits).
Murray,
DKIM is not enforcing RFC5322's format. Nor is it reasonable to expect
that SMTP has either.
It is reasonable to expect security related protocols validate input.
Whether a message gets rejected or dropped is immaterial. For DKIM's
output to be usable, it must be clear what was signed without expecting
subsequent message handlers to adopt bottom-up selection. Otherwise,
DKIM can not be safely deployed in an incremental fashion as claimed in
its introduction.
-Doug
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