Application Research Of Digital Signature Schemes In Electronic Cash System

With the development of Internet,electronic commerce has attracted more and more attentions as a new commerce mode. Electronic payment systems are significant for electronic commerce. Electronic cash is a very important electronic payment system. In this thesis,we pay our more attention to how to use some modern cryptographic technologies, such as Group Digital Signature, Blind Digital Signature, Group Blind Digital Signature to construct a new electronic cash system. The whole thesis was composed of two parts: First, study on cryptographic constructs called Group Digital Signature, Blind Digital Signature ,Group Blind Digital Signature; Second, study on electronic cash system.(1) Recently, group signatures, Blind Signatures and their combination result called group Blind Signatures which have been widely used in political area, military area and commerce area have been becoming the hot topics of modem cryptographic technology. For example, they have already been used in electronic election,electromc voting and electronic cash. This thesis first introduced the famous Blind Group Digital Signarure-LR98 , and then annoysis the securety and the efficiency of this signature, proved that this original scheme was not safe enough to resist a coalition-attack , in the end, provided a modified scheme of the original scheme to avoid the attack.(2) Electronic payment systems are essential tools for E-commence. Electronic cash will play an important role in the future due to its unique anonymity property: About 20 years works in the literature of electronic cash are analyzed. Some open problems that should be studied are presented. The future of electronic cash system will be predicted. Based on the fair Blind Group Digital Signature, a new multi-bank electronic cash system is proposed. This new electronic cash is off-line and fair, it also supports coin tracking and owner tracking. The new electionic cash system is more securative than LR98 E-cash,and have the same efficiency as LR98 E-cash.