From: rjc@gnu.ai.mit.edu
Date: Tue, 5 Oct 93 19:55:07 PDT
To: honey@citi.umich.edu (peter honeyman)
Subject: Re: Chaum on the wrong foot?
In-Reply-To: <9310052038.AA09338@toad.com>
Message-ID: <9310060253.AA19384@kropotkin.gnu.ai.mit.edu>
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peter honeyman writes:
>i am replying to a message that is six weeks old.
> 
> hal, chaum may be barking up the wrong tree, but that doesn't mean
> that his students are.  i read a couple of digital cash papers last
> night and was struck by this statement in one of them:
> 
>     Techniques have been developed that ... allow the construction of
>     off-line electronic cash systems that are secure for the bank, yet
>     at the same time honest users of the system are guaranteed to
>     remain completely anonymous.  This holds in a very strong sense:
>     the security of banks is not compromised even if all users and
>     shops collaborate in such an attempt, and the privacy of honest
>     users cannot be violated in any cryptanalytic way even under
>     adversarial behavior of the bank in coalition with all the shops.
> 
> 					  Stefan Brands, CWI

  This could refer to observer based protocols. I don't see anything in the
above paragraph to indicate that they have invented a digital coin. I don't
see how offline non-observer based cash could possibly work. (e.g.
I send a copy of my cash to someone in Europe and we "spend" them 
simultaneously)


-- Ray Cromwell        |    Engineering is the implementation of science;    --
-- EE/Math Student     |       politics is the implementation of faith.      --
-- rjc@gnu.ai.mit.edu  |                         - Zetetic Commentaries      --