ecash protocol: Part 1

[Ian Goldberg]

In article <v02120d05acd986f50e5e@[199.2.22.120]>,
Douglas Barnes <cman at communities.com> wrote:
>
>> From what I gathered from Doug's posts a little while back, the _client_
>>stuff is perfectly fine; only the _bank_ stuff is Chaum-patented.
>>
>
>This is exactly backwards. Also, it is entirely possible that they
>have structured the protocol to make sure that both sides have to
>practice some element of Digicash intellectual property. What I
>said was "it is possible to create an anonymous digital cash system
>where the bank does not infringe and the client can optionally
>infringe or not infringe (sacrificing anonymity)."
>
>(See: http://www.communities.com/paper/agnostic.html)
>
>

Yes.  D'oh.  I realized this while talking to Dave shortly after I posted.
All the bank does is send back the cube root of what it received from the
client.  If the client wants to multiply by the cube of a random number
before sending to the bank, and dividing by that random number after,
that's up to it.  The system Hal mentioned, though (client sends payment
requests, receives payments, deposits them), still doesn't infringe,
as long as it doesn't do _withdrawls_.

   - Ian "Hoping he hasn't goofed up again..."