With the advent of an on-line shopping mall over the Internet, research about electronic commerce has been active recently. Various payment methods have proposed to pay for products in the WWW environment. Electronic cash, an electronic equivalent of real paper cash, is one of these ways. When we use electronic cash as a payment method, two important issues need to be addressed. One is full anonymity and the other is efficient double-spending prevention. The previously proposed systems suffer from weak anonymity or inefficient double-spending check.
In this thesis, we propose Independent Serial Number Service(ISNS) protocol that effectively provides full anonymity and avoids double-spending. ISNS utilizes the desirable aspects of the existing systems and prevents some of their problems. This protocol features one serial number server that creates and maintains unique numbers of electronic cash in use by users. The serial number server is separated from the bank server in charge of issuing electronic cash. We implement an electronic cash payment system based on SSNS protocol. The system ensures full anonymity and efficient double-spending prevention. With secure cryptography, our system makes sure that the details of purchase are not eavesdropped by hackers. Also, our system can be used, irrespective of small or large payments.
