An Exchangeable E-Cash Scheme by E-Mint

The electronic payment systems are gradually used after the electronic commerce was in fashion. However, the electronic cash (E-cash) in every electronic payment system cannot be circulated to other e-cash systems. In addition, the e-cash usually presents a fixed amount of money and should be used the whole amount in a trade. It is difficult to have the change back when the purchase price is lower than the amount of the e-cash. Herein, we proposed an e-mint system based on the Song-Korba´s scheme which offered the anonymity and no-repudiation properties. The proposed scheme not only can circulate all e-cash systems but also allows exchanging a large amount of the e-cash into some small amounts of e-cash. Therefore, anyone can keep the remainder money if he does not spend the whole amount of the e-cash in a trade.