Question regarding common modulus on elliptic curve cryptosystems AND E-CASH

James A. Donald jamesd at
Wed Mar 24 18:37:05 EDT 2010

On 2010-03-23 1:09 AM, Sergio Lerner wrote:
> I've read some papers, not that much. But I don't mind reinventing the 
> wheel, as long as the new protocol is simpler to explain.
> Reading the literature, I couldn't  find a e-cash protocol which :
> - Hides the destination / source of payments.
> - Hides the amount of money transferred.
> - Hides the account balance of each person from the bank.
> - Allows off-line payments.
> - Avoids giving the same "bill" to two different people by design. 
> This means that the protocol does not need to detect the use of cloned 
> "bills".
> - Gives each person a cryptographic proof of owning the money they 
> have in case of dispute.
> I someone points me out a protocol that manages to fulfill this 
> requirements, I'd be delighted.
> I think I can do it with a commutative signing primitive, and a 
> special zero-proof of knowledge.

Gap Diffie Helman gives you a commutative signing primitive, and a 
zero-proof of knowledge.

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