From: Bryce <wilcoxb@nag.cs.colorado.edu>
Date: Thu, 19 Oct 95 13:01:33 PDT
To: tcmay@got.net (Timothy C. May)
Subject: Polymorphic e-cash schemes  was: digital cash and identity disclosure
In-Reply-To: <acabe4df3f021004b9f5@[205.199.118.202]>
Message-ID: <199510192001.OAA25866@nag.cs.colorado.edu>
MIME-Version: 1.0
Content-Type: text/plain



-----BEGIN PGP SIGNED MESSAGE-----

Some cpunks a couple of months ago told us about "agnostic" e-cash
anonymity schemes in which the e-bank accepts both blinded and
un-blinded coin requests, leading to anonymity or non-anonymity at the
choice of the client.  They pointed out how this would be very
easy to implement, based on the current Chaumian system.  I think this
is an excellent idea for social-engineering reasons and I congratulate
them on bringing it up.  (Unfortunately I don't have time right now 
to look up who it is that I am congratulating...)


Perhaps a similar "polymorphism" could be implemented with regard to
on-line/off-line clearing.  When you as a payee receive a Chaumian
Ecash coin, you can choose based on several factors (including
reputation of the payer if he chooses to make his nym known to you,
size of the transaction, time of day, or whatever) to either accept it
immediately and credit the payer with whatever it is you are selling,
or to delay completion of the transaction while you attempt to deposit
the coin with your e-bank.  (If you are wary of "payee-ID proof
stings" like Lucky Green is, then you can go ahead and launder your
coin through an anon account during this interval...)  If your payer
has already spent this coin, then the bank will inform you immediately
and you can cancel the transaction.  (And take whatever other actions
you consider appropriate...)


It seems like such a scheme would include all of the advantages
(off-line clearing) of Chaumian Ecash as well as those
(double-spending prevention) of the on-line clearing systems.  Thus,
TCMay's objections to current Chaumian Ecash would not apply to this
new variation.


I hope that this isn't an old-news yawner to you experts.


Regards,

Bryce

Announcement:  I'm going to be fading off the the c'punks list for a
while, so be sure and Cc: me if you want me to read your post.

signatures follow


            "To strive, to seek, to find and not to yield."   
    <a href="http://ugrad-www.cs.colorado.edu/~wilcoxb/Niche.html">

                          bryce@colorado.edu                   </a>



-----BEGIN PGP SIGNATURE-----
Version: 2.6.2
Comment: Auto-signed under Unix with 'BAP' Easy-PGP v1.01

iQCVAwUBMIauO/WZSllhfG25AQGXHwP+MEpnPvpj81fV66HEb8rozlMepnol3nj5
/d73LQpMxB7fLcMEDmISNQef/eU39zId8EZ1XCW7X3AujMBa4OjuBgl3+vdrAKo9
DIb6imXxc+E9dyHp0i9y/FZtzkOXKF6Abwy3SYMOSyaI2HsiCyUx2tEW/6OzDJTi
7YyOqR+FkNQ=
=cpK7
-----END PGP SIGNATURE-----