From: Karl L. Barrus <barrus@tree.egr.uh.edu>
Date: Tue, 12 Jan 93 20:00:31 PST
To: cypherpunks@toad.com
Subject: security of constructed addresses
Message-ID: <9301130359.AA00390@tree.egr.uh.edu>
MIME-Version: 1.0
Content-Type: text/plain



Alert!  Hal Finney has alerted me to a problem with the way my script
builds an anonymous remailer chain.  Simply saving eachheader portion
into a seperate file and running pgp on the pieces reveals each link
in the chain.

The solution (also from Hal Finney) is: hide the intermediate hops
until they get to the machine that needs them.
(machine1, encrypt1(machine2, encrypt2(machine3, encrypt3(user@dest))))
Here, the entire header is decrypted at each remailer, revealing the
next destination to that remailer only.  No peeking ahead!  The only
remailer that will be revealed is the first one, where mail has to be
sent anyway.

I'll rework the script, provide a ksh version, and write a little help
file ASAP. 

/-----------------------------------\
| Karl L. Barrus                    |
| barrus@tree.egr.uh.edu (NeXTMail) |
| elee9sf@menudo.uh.edu             |
\-----------------------------------/