No Subject

[Anonymous <remailer-admin@chaos.bsu.edu>]

Kudos to Hal Finney for his descriptions of Stefan Brand's offline
cash.  As with other offline cash protocols it contains the following
assumption:

> Let's call the user Irving, and
> the number which encodes his identity (it might just be his bank account
> number in this case) we will call I.    

What happens when we've caught Irving double spending (or million
spending?)  Is it guaranteed that Irving will have enough in his
bank account to cover the fraud?  I don't see any way to guarantee
that except for absurdly large security deposits.  Also, are
bank accounts required to be in True Names so that multi spenders
can be caught and punished?  If so, how do we prevent  the use of
numbered accounts, Duncan Frissel's nom de guerre accounts, etc. 
and do we really want to set up that kind of True Name infrastructure?

Also, what about stolen coins?  If Irving can succeed in
stealing a coin from Jane without her knowledge, Irving
can spend it untraceably as many times as he can get away
with (perhaps thousands or even millions, depending on what
security precautions we layer above the offline cash), and
Jane gets fingered.  On the other hand, Jane might simply
give Irving some coins, plausibly claim they were stolen, and 
split the proceeds from Irving's spending spree.

In general, multi spending might occur because of accident,
malice, or a combination of those two factors.  How do we
distinguish between accident and malice to determine liability,
reputation loss and/or punishment?