ietf-dkim
[Top] [All Lists]

Re: [ietf-dkim] Re: Replay attacks and ISP business models

2005-08-07 15:17:48
I agree. I think that the thing that really ought to
be proven here is whether "replay" is a real threat or
not.

If replay does become a problem, then what is the response?

Kick off the users playing replay games, I'd guess.  Disregarding joe jobs
(which I see no reason to expect will ever be anything other than an edge
case) the sender has to be in cahoots with the person doing the replay,
you know who he is since you have his DKIM signed mail, so you whack him.

While John Levine wants mailing lists to re-sign their messages to
permit repeat thresholds on the same signatures, there would also be
advantages for mailing list to not re-sign an already signed message.

I think every agent that sends mail should sign the mail they send, but I
am not so foolish as to think this will happen any time soon.  Until then,
there will be many mailing lists whose behavior is technically
indistinguishable from a "replay attack."  I'm still waiting for someone
to explain how you stop replay without also wrecking mailing lists, other
that by implausibly labor intensive approaches like manually whitelisting
every legitimate remailer in the world.

Regards,
John Levine, johnl(_at_)iecc(_dot_)com, Primary Perpetrator of "The Internet 
for Dummies",
Information Superhighwayman wanna-be, http://iecc.com/johnl, Mayor
"I dropped the toothpaste", said Tom, crestfallenly.
_______________________________________________
ietf-dkim mailing list
ietf-dkim(_at_)mipassoc(_dot_)org
http://mipassoc.org/mailman/listinfo/ietf-dkim