A user registers a user public key PKU as a pseudonym at a trustee or issuer and obtains an signature for the pseudonym as a license. The sends the pseudonym, PKU identification information IdU and the amount of withdrawal x to the issuer institution. The issuer increments a balance counter of the pseudonym by x, then generates an issuer signature SKI(PKU, x) with a secret key SKI, and sends the issuer signature as an electronic cash to the user. The user verifies the validity of the issuer signature with a public key SKI, and if valid, increments an electronic cash balance counter Balance by x. At the time of payment, user sends the public key PKU and the license to a shop, and the shop verifies the validity of the license, and if valid, sends a challenge to the user. The user attaches a signature to the challenge with user secret key SKU, then sends it to the shop together with the amount due y, and decrements the electronic cash balance counter by y.

 
Web www.patentalert.com

> System and method for contract authority

~ 00348