Off-line compatible electronic cash method and system

US5832089A · kind A · utility

Assignee

• Sandia Corporation · US

Inventors

• David William Kravitz · San Jose, US
• Peter S. Gemmell · Albuquerque, US
• Ernest Brickell · Albuquerque, US

Key dates

• Filing date: Jun 7, 1995
• Grant date: Nov 3, 1998
• Expiry date: Jun 7, 2015

Classification

• Technology area (CPC G): Physics
• CPC primary: G06Q20/383
• WIPO field: IT methods for management
• WIPO sector: Electrical engineering

Abstract

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 An electronic coin is withdrawn from the bank B by the user U and an electronic record of the electronic coin is stored by the bank B. The coin is paid to the payee S by the user U. The payee S deposits the coin with the bank B. A determination is made that the coin is spent and the record of the coin is deleted by the bank B. A further deposit of the same coin after the record is deleted is determined. Additionally, a determination is made which user U originally withdrew the coin after deleting the record. To perform these operations a key pair is generated by the user, including public and secret signature keys. The public signature key along with a user password z.sub.u,i and a withdrawal amount are sent to the bank B by the user U. In response, the bank B sends a coin to the user U signed by the secret key of the bankindicating the value of the coin and the public key of the user U. The payee S transmits a challenge counter to the user U prior to receiving the…