From: Gary Howland <gary@systemics.com>
Date: Sat, 7 Dec 1996 06:06:20 -0800 (PST)
To: Black Unicorn <unicorn@schloss.li>
Subject: Re: Mondex
In-Reply-To: <Pine.SUN.3.94.961206110148.1568B-100000@polaris>
Message-ID: <199612071408.PAA22126@internal-mail.systemics.com>
MIME-Version: 1.0
Content-Type: text/plain



> Can anyone briefly discuss the anonymity features (or lack thereof) for
> Mondex?

Any anonymity derives from the fact that Mondex cards are bearer devices.  
Sure, a real name may have to be used to obtain a card, but I don't see how 
Mondex can prevent the cards being passed on.  One would guess that they could 
only realistically achieve this if the card were embedded in a credit card or 
something similar.

As far as I can see, the transactions have to be untraceable, as long as user 
to user transactions can occur, and there is no limit to the number of 
transactions per card.  Even if the cards record the last 300 (as rumours 
suggest) transactions, that just means I have to perform 300 transactions 
between a pair of my cards in order to erase the "interesting" history.  The 
ability to erase the history could only be prevented by restricting the number 
of transactions per card, or by preventing card to card transactions.

There does seem to be some scope for other tracing tricks however.  For 
instance, it may be possible for a card to remember IDs of the last few 
hundred cards it has communicated with.  However, if we know this, then we 
just have to have a few hundred cards of our own to "erase" the interesting 
IDs.

Bear in mind that it may be possible for all "electronic coins" that are 
issued to be given a serial number.  There would be no tricks to circumvent 
this, but of course tracing can only occur when the money leaves and enters 
the bank (and perhaps at every shop counter), so the usefulness of this is 
limited if many user to user transactions are occurring.  I don't think Mondex 
does this, though, since the memory requirements seem to be too large for 
todays smartcards.  What I *guess* Mondex does do though, is "mark" coins in 
certain situations - eg. a kidnapper is paid a ransom via cellphone in another 
country using Mondex, but the coins are marked. They will stay marked no 
matter how many times they are transferred, and eventually will be caught by 
the system (either as they are deposited into an account, or perhaps via shop 
terminals looking for the mark).  This would not ensure the catching of the 
kidnapper, but at least gives the authorities a start.  It may also be 
possible to put a time limit on these expired coins, so that the money 
"vanishes" some time after the baby is returned alive (or whatever).

Gary