On Wed, 24 Aug 2005, Douglas Otis wrote:
I don't see where that talks about using the revocation ID to detect
forgery.
The recent suggestion was to consider the binding of the
mailbox-address/ signing-domain/revocation-identifier by the MUA as an
opportunistic identification, rather than attempting less protective
domain-wide assertions by the SSP. The MUA is able to associate visual
items from prior correspondents and obtain a higher granularity and
history of signed message sources without using any DNS lookups.
That seems plausible, but it assumes that the revocation ID will be varied
per sender and I don't think this will always be the case. For example:
attack: Mr Vendetta signs up for marketing email from example.com, then
spams it widely in order to damage the company's reputation. (This is a
direct reputation attack, as opposed to the parasytic reputation attack we
have considered so far.)
defence: Example.com wants to revoke email sent to Mr Vendetta without
affecting their other customers. Therefore they use a revocation ID per
recipient.
This doesn't break your scheme, but it does make it look a bit shaky.
Tony.
--
f.a.n.finch <dot(_at_)dotat(_dot_)at> http://dotat.at/
BISCAY: WEST 5 OR 6 BECOMING VARIABLE 3 OR 4. SHOWERS AT FIRST. MODERATE OR
GOOD.
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