From: nobody@rosebud.ee.uh.edu
Date: Thu, 30 Sep 93 12:31:56 PDT
To: cypherpunks@toad.com
Subject: REMAIL: digicash
Message-ID: <9309301926.AA20380@toad.com>
MIME-Version: 1.0
Content-Type: text/plain


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Cypherpunks,

I've been experimenting with a primitive digital cash system for
remailers.  Originally I had hoped to combine the remailing and
banking functions of the elee7h5@rosebud remailer, but for now I have
an even more primitive cash system implemented at elee6ue@rosebud.  It
seems to be performing as expected.

A digital cash accepting remailer, along with a good positive
reputation system, is the "crypto-anarchist" answer to labeling
anonymous mail with subjects and/or usernames.  (Of course, a subject
that enables anonymous mail to blend in is great - such as "Re: your
mail").  (Incidentally, since running pgp to get the signature from a
pgp-signed message is expensive, I patched the script I use for
positive reputation to give the option of checking signatures or not,
if anybody is interested.)  Currently, the only objection I've heard
to anonymous mail is "somebody can abuse it"; future remailers will
require payments, helping to address this concern.

Basically, the remailer recognizes a Digicash pasting token, and for
now the cash is a string of letters and numbers.  Before remailing,
the digicash is extracted and looked up in a cash list (which I
create).  If the cash is in the list, it is assumed to be valid, and
the list is rewritten minus the cash string just used.  If the cash
isn't present, it is assumed to be invalid, and an insufficient funds
message is remailed instead.  The remailer does not keep a list of
"spent" cash strings, so there is the possibility of duplication (once
in every 36^60 times).  As far as correlating the cash used to
individual and a message, I can only assure you I could care less
about the required bookkeeping.

The pasting token looks like the others, and you use it in a similar
way -

- ----------8< cut here >8----------
::
Digicash: <here is the string>

- ----------8< cut here >8----------

For example, I "paid" for the remailing of this message with

- ----------8< cut here >8----------
::
Digicash: BcKjSoUEQaTam9xPs0oso2j0UVVb1M6OyxTn8QSX0rdT3eUIH4Vq1rXEpYH1D

- ----------8< cut here >8----------

(Now, the above cash string should be invalid! :-)

The way I'm distributing valid cash for the remailer is by email -
mail me and I'll send you some valid cash strings.  No charge :-)

Karl L. Barrus
<klbarrus@owlnet.rice.edu>


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