REMAIL: Cover traffic

[Hal <hfinney@shell.portal.com>]

Several people have suggested that the remailers could send bogus
messages amongst themselves in order to allow more "confusion and
diffusion" of the other messages passing through the remailer network.
The remailers could then batch up incoming messages fairly frequently
and still have many messages in a batch.

The problem with this that I see is that, looking at the remailer
network as a whole, you still may have one message in and one message
out a short while later.  The fact that it was temporarily mixed up
with a bunch of other messages doesn't help much if this message is the
only one to leave the network.  If the Opponent has the ability to
monitor all traffic into and out of all nodes of the network (as he
would have to do anyway to defeat remailers even without this cover
traffic) then he will easily be able to find the messages which are not
aimed at other remailers.

For cover traffic to be useful, it would have to be indistinguishable
from real traffic as it enters and leaves the network.  So messages
aimed at known "bit bucket" addresses, or at a few cooperating
individuals who accept and discard incoming addresses (the same thing,
really) will not help.

Hal