Application Research Of Digital Signature In E-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. It is significant to design a secure and efficient electronic payment system. The jumped-up payment tool--electronic cash is more adaptive than the credit card and electronic check which is widely used at present,because it is characterized by the anonymity,off-line practicability and transferability.Digital signature is one of the effective methods to protect network and it ensures integrality of messages,and tells identification and undeniability of the sender. Digital signature becomes researchers'attraction in the field of network security. In this thesis,we pay our more attention to how to use some modern cryptographic technologies, such as Digital Signature, to construct a new electronic cash system.In this paper our work aiming to such a challenge is as follows:(1)Introduction to the characteristics and classification of digital signature, digital signature schemes based on a private-key system or public-key system, and the core concepts of public-key system. Special signatures are key technologies of electronic cash, some typical special signature, such as Group signature, Blind signature, Group blind signature, Forward-secure digital signature, proxy signature and their applications in electronic cash are introduced in this paper.(2)The development history and the research's present situation of electronic cash system are summarized, and the relevant knowledge about cryptology in the electronic cash is discussed. There are many electronic cash systems based on the ACJT group signature at present. In this paper, we analyze the advantages and deficiencies of two typical schemes.(3) We design Forward-secure E-cash system with efficient revocation. The new system provides revocable anonymity, member revocation, and prevents the double-spending. The signing keys of bank evolve over time while the public key stays fixed, and when current signing key is exposed,previously issued coins remain valid which reduces the loss of bank.(4) We design a secure and efficient electronic cash system based on a new forward-secure group signature scheme. The new system provides revocable anonymity and prevents the double-spending, blackmail and juggling the sum of money, so it is secure.(5)To achieve secure electronic payment, based on proxy signature scheme and Brands' e-cashscheme, this paper presented a new e-cash system with multiple banks.The user's anonymity is protected under normal conditions, and it can be revoked by the issuing bank under the supervision of the central bank if anything abnormal happens (such as requirementby law).