Polymorphic e-cash schemes was: digital cash and identity disclosure

[Timothy C. May]

At 2:03 PM 10/20/95, Hal wrote:

[Bryce's proposal elided]

>Unfortunately, in order for a coin to be POTENTIALLY spent in an off-line
>way, the protocols require that the identity of the withdrawer be
>embedded, in blinded form, within the coin data.  It is this step that
>Tim and others object to, because among other things it requires
>participants to securely identify themselves to the bank, hence does not
>work well in a fully anonymous society.  The reason for this requirement
>is that if the coin is double-spent, this is not found out until
>afterwards, and so the identity of the cheater has to be available so the
>bank can go after him.
>
>So letting the payee choose whether to deposit the coin right away or
>wait until later will not address this basic privacy problem with offline
>cash.

Indeed.

And let me clearly state that I am not proposing an either-or situation. In
a real ecology of competing digital cash schemes, unconstrained by the
software patent issue we now are facing, there would likely be "online
clearing only" systems, "offline clearing only" systems, and various
hybrids and variants. The market would then decide, based on transaction
costs, convenience, security, anonymity features, etc. As with the "real"
economy, where a variety of financial instruments coexist.

--Tim May

Views here are not the views of my Internet Service Provider or Government.
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Timothy C. May              | Crypto Anarchy: encryption, digital money,
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