Technical Report TR-98-15, LCIS, Tamkang University, Taiwan, R.O.C., September 1998.

Abstract. In this paper, a prepaid micropayment scheme is demonstrated. Same as all the other prepaid schemes, profits of the merchants are protected. However, in this proposed scheme, fairness for the customers are also considered. More precisely, in this new system, the merchant after receiving prepaid money can only claim that the customer has already spent a specific amount of money by showing the required secret value which can only be received from the customer using as a payment.