NetCard - A Practical Electronic-Cash System

Our recursive hashing technique greatly reduces the computational complexity in applications where a series of low value payments are made to the same merchant. We have shown how it can be used in simple payment schemes based on both the smartcard and the online processing models of electronic commerce, and can also provide some novel and valuable features, such as a security recovery facility that does not depend on either the legacy systems or the SET protocols. It is an open problem whether hashing techniques can be combined with the more complex anonymous cash schemes.