From: xpat@vm1.spcs.umn.edu
Date: Fri, 27 Jan 95 09:54:01 PST
To: cypherpunks@toad.com
Subject: Re: "Subway" remailers
Message-ID: <9501271753.AA10408@toad.com>
MIME-Version: 1.0
Content-Type: text/plain



 maher@kauai.UCSD.EDU (Kevin E. Maher) writes:
>        I think what you've described is essentially a "secondary"
>remailer, one which only communicates with other remailers in messages
>of a fixed size.  I'm pretty sure mixmaster can do this, and additionaly
>can split a message into chunks and send them on their way via differen
>paths.
>
>        If I've misinterpreted what you were describing, please correctme.

Hmmm...  think of an egg carton, filled with anywhere between zero and
twelve eggs. Each egg has its own itinerary as to how many stops it
wants to make at other remailers, and whether it wants to change
cartons. The eggs would be entire messages, and could "get off" at
any particular stop, or at a random stop (based on # of rides(hops?)).
The entire carton would be encrypted from one stop to the next.

I would anticipate that the single-message architecture of the cpunk
remailer would be retained, and that "riding the subway" would be an
optional feature. Of course with "passenger" exchange and waiting
you essentially get the mixmaster effect, except you are blind to
the actual pathway. (remember the MX-missle system, which planned on
moving ICBMs from launch site to launch site in an underground matrix
of tunnels?) The only thing you would see from the outside is regular
pulses of large cargo-carrying (or not) message containers. It might
be a partial cover-traffic solution as well, though you still have to
worry about entering and exiting the subway system, it's just that it
somewhat breaks the identifiable direct traffic-trace links.

An even more advanced feature could allow an individual to submit
an entire container (loaded with different messages) to the subway
system (although this may give an attacker clues about any weakness
in randomizing pathways internal to the system, for users utilizing
default features). Imagine only submitting one or two messages a
day that delivered twenty-five. That might really furrow a traffic
analyst's brow. More or less that extends the subway paradigm
outside the ring of the system, at least partially, I would guess.

I am unsure if there is an existing term for this, but how about
"composite mail" containing "aggregate messages"?

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