[ietf-dkim] Corner cases and loose ends, was , draft-vesely-dkim-joint-sigs

[Charles Lindsey]

On Sun, 03 Oct 2010 07:13:55 +0100, Michael Deutschmann  
<michael at talamasca.ocis.net> wrote:

> And there's the rub.  The problem is that a major threat we anticipate,
> is that should a means be added to append a footer without breaking the
> signature, bad guys will find short legitimate messages and replay them
> with a footer containing spam.

I would suppose that an added footer will usually take the form of an  
extra part with Disposition: inline in a multipart/mixed. Insofar as this  
is not the current convention it ought to be (if only so that users can  
filter out those annoying footers).

In that case, the clean solution, in lieu of the little-used 'l=...',  
would be to have some mechanism for speciffying exactly which  
parts/atachments of a messsage had been included in the signature.

Whether it is now too late to add such a fundamental enhancement to DKIM  
is an interesting question, even though it might enable various useful  
possibilities. But at least it ought to be looked into.

-- 
Charles H. Lindsey ---------At Home, doing my own thing------------------------
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