An off-line electronic cash system with revokable anonymity

Many electronic cash systems have been proposed with the proliferation of the Internet and the activation of electronic commerce. Maitland and Boyd proposed at ICICS 2001 an offline electronic cash system based on a group signature scheme proposed by Ateniese, Camenisch, Joye and Tsudik. Their scheme cannot be used to solve blackmailing and other anonymity problems such as money laundering and illegal purchases. In this paper we extend the electronic cash system of Maitland and Boyd to prevent blackmailing, money laundering and illegal purchases by using a secure coalition-resistant group blind signature scheme.