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Off-line compatible electronic cash method and system

United States Patent

5,832,089
November 3, 1998
View the Complete Patent at the US Patent & Trademark Office
Sandia National Laboratories - Visit the Intellectual Property Management and Licensing Website
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 An electronic coin is withdrawn from the bank B by the user U and an electronic record of the electronic coin is stored by the bank B. The coin is paid to the payee S by the user U. The payee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 coin.
Kravitz; David W. (Albuquerque, NM), Gemmell; Peter S. (Albuquerque, NM), Brickell; Ernest F. (Albuquerque, NM)
Sandia Corporation (Albuquerque, NM)
08/ 474,035
June 7, 1995
This invention was made with Government support under Contract No. DE-AC04-94AL85000 awarded by the United States Department of Energy. The Government has certain rights n the invention.