Proxy Blind Signature And Its Application In Electronic Cash System

The development of the computer technology takes us into a information society, and electronic commerce activities is developing rapidly, so how to ensure the security of information has become an important problem. The digital signature which can ensure the security of information has been widely researched. Many special digital signature schemes have emerged, including proxy blind signature. The proxy blind signature not only has the properties of proxy signature, but also has the properties of blind signature, so it plays an important role in electronic cash systems.In this paper, proxy blind signature has been improved, and electronic cash system has been studied, the main work is as follows:Firstly, a proxy blind signature which based on identity is analyzed, it was found that attacker can forge the proxy authorization and PKG can forege proxy blind signature successfully, the third trusted party PKG is not always honest. An improved proxy blind signature scheme is proposed by increasing secret value information of users, and can overcome the malicious-but-passive PKG attack existing in the original scheme.Secondly, a certificateless proxy blind signature scheme is analyzed, it was found that the scheme can not resist public key replacement attack and malicious-but-passive KGC attack, in order to avoid these attacks, an improved certificateless proxy blind signature scheme is proposed by changing public key generate process and bounding the identity and public key of users. The security of the new scheme is analyzed, and is proved to be existentially unforgeable under random oracle model, it can also overcome the problems of original scheme.Thirdly, a certificateless proxy blind signature scheme is analyzed, it was found that the scheme can not resist malicious-but-passive KGC attack, ordinary attacker’s attack and the original signer collusion with KGC can get proxy key. In order to avoid these attacks, an improved certificateless proxy blind signature scheme is proposed by bounding the identity with public key of users and change signature process, it can also overcome the problems of original scheme..Fourthly, an electronic cash system which mostly based the improved certificateless proxy blind signature is proposed, and it’s security is analyzed.