A fair off-line e-cash system with group signature

This paper describes the research results and development of fair off-line e-cash systems so far, and points out that in these systems, the bank can compute the double-spender’s account secret key, thus the bank can impersonate the double-spender to withdraw from the double-spender’s account. This article utilizes anonymity control and group signature to address this shortcoming. Foundation item: Supported by the National Natural Science Fundation of China (90204015) Biography: SU Yun-xue (1975-), male, Ph. D. research direction: the software and theory of computer and information security.