Re: RfC: Taxonomy of mix batching approaches (draft)

[Roger Dingledine <arma@mit.edu>]

----- Forwarded message from owner-mixminion-dev@freehaven.net -----

Date: Tue, 3 Sep 2002 18:36:41 -0700 (PDT)
From: Len Sassaman <rabbi@abditum.com>
To: <mixminion-dev@freehaven.net>
Cc: <freehaven-dev@freehaven.net>, <syverson@itd.nrl.navy.mil>,
	<Andrei.Serjantov@cl.cam.ac.uk>
Subject: Re: RfC: Taxonomy of mix batching approaches (draft)

On Mon, 2 Sep 2002, Roger Dingledine wrote:

> http://freehaven.net/doc/batching-taxonomy/taxonomy.pdf
> (or http://freehaven.net/doc/batching-taxonomy/taxonomy.ps)

About Mixmaster dummy messages:

Dummy messages are not fixed at 5 hops. They use the value of the CHAIN
setting for picking their chains (which is by default *,*,*,*), or four
random remailers. The user/remop can change this.

Also, Mixmaster currently does not generate dummy messages when sending
from the pool. Dummy message generation is entirely up to the user (and
many remops have a cron setting for dummy message generation.)

We're thinking of changing that and having dummy messages generated each
time a message is placed in the pool.

The attack described in the paper, where the anonymity set is limited to
2, is not as easy if we generate multiple dummy messages upon message
arrival. Then, if two good messages exit the pool, the attacker won't know
for certain that one of them is good. You could have a pool_send where
multiple dummy messges, but no real message, are sent.

----- End forwarded message -----