Re: [Asrg] 6. Proposals - Challenge/response - CRI

[david nicol <whatever@davidnicol.com>]

On Wed, 2003-08-20 at 12:42, Deven T. Corzine wrote:

> > > > I think the only really significant semantic suggestion I'm making
> > > > is that a hash of the body of a message should be included to
> > > > prevent forgeries of level-two systems.
> > 
> > That has been mentioned before and is a pretty good idea. It also 
> > alleviates some privacy concerns since the originating MTA/MUA does not 
> > have to store copies of messages, but can store MD5 hashes instead.
> 
> Using a hash is an obvious thing to do, but it begs the question of exactly
> what you're hashing.  You can't safely hash the entire message because the
> headers change on every hop, at least for Received: lines.  Other headers
> might be mangled or normalized as well.  You can ignore the header, but it
> would be good to validate parts of it.  Even if you just hash the body, you
> have to be concerned about the message being mangled by intermediate MTAs.


I imagine one would hash all the MIME parts together.  Or do whatever
GPG does with a MIME message.  This but has been solved, there is only
to select an approach and approve it.



-- 
David Nicol / If at first you don't succeed, use a bigger hammer. 
                                        http://gallaghersmash.com


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