Research On Electronic Cash With Changeable Anonymity

With the development of electronic commerce, electronic cash system has become an unsubstitutable means because of the particular function protecting the payer and the payee's privacy.In the e-cash system, anonymity is a very important factor. At first, the design of e-cash is complete anonymous, later this kind of e-cash system is proved having some faults, so the anonymity-revoking e-cash system is designed. In this kind of e-cash, the anonymity can be revoked under some conditions to prevent the crimes from overspreading.According to the consuming demands and consuming psychology, consumers have different requirements to anonymity when deal on the Internet. To the small deals, the most consumers except to be anonymous, but to the greater deals anonymity is not required, or only conditional anonymity. While to the criminal on the Internet, their demands to anonymity are greater, and the sum of anonymous deals is tremendous, to those deals, there should be no anonymity, at most conditional anonymity. Therefore, if an e-cash system consists of two kinds of e-cash (complete anonymous and anonymity-revoking), it is very convenient to the consumers and can promote the e-commerce, at the same time can prevent the crimes from overspreading.So an E-cash system with changeable anonymity is studied and designed in this paper. A complete anonymous e-cash named "pin money" is introduced, signed by blind RSA signature scheme. Then the blind Schnorr signature scheme is improved to satisfy the demands of anonymity-revoke. According to the improved signature scheme, the anonymity-revoking e-cash is accomplished. The emphasis lies on the withdrawal,payment and deposit of this e-cash, the mechanism of anonymity revocation and the mechanism of detecting double-spending are achieved.In order to protect the anonymity of consumers in change-making deals, a new method is proposed, that is, the change-making protocol is processed direct to the bank not to the merchant. In the end the merchant's anonymity is discussed.As a result, the e-cash system with changeable anonymity accords with people's consuming habit much more, fits the development of e-commerce much more...