An off-line electronic cash system having an electronic coin, a bank B, a payee S, and a user U with an account at the bank B as well as a user password z.sub.u,i, has a method for performing an electronic cash transfer. An electronic coin is withdrawn from the bank B by the user U and...http://www.google.es/patents/US5832089?utm_source=gb-gplus-sharePatente US5832089 - Off-line compatible electronic cash method and system
Off-line compatible electronic cash method and system
