Research And Implement Of Digital Signature System

Human beings have entered into the information era with the development of computer and network technologies, thus the security problem of information has become the fundamental matter, and has become a new important subject in the information science. The digital signature is one of key techniques in information security, especially in the authentication, data integrity, and non-repudiation. It has been widely used in military, communication, e-commerce and e-government, etc., and will become more and more popular after the e-signature law is put in practice.First of all, the article discusses and analyzes the currency and development trend of digital signature. Second the correlation technique of digital signature is discussed, including mathematics foundation of digital signature, the correlation basic conception of digital signature, the arithmetic of hash function and so on. Third, two kinds of digital signatures based on discrete logarithm are deeply analyzed. Through the reach of some possible attacks to the ElGamal scheme and the analysis of the security of DSA scheme, considering the security of digital signature scheme and the speed of signing and verifying, an improved digital signature scheme is proposed, and a digital signature system is designed and implemented. In the improved scheme, an improved function of signature and verification is used, which don't need inverse operation, then it can play down the calculative time , and the speed of scheme is increased. At the same time, a longer 256 bit hash function is used to increase the security of digital signature scheme, which effectively resists birthday attack. At last, on the base of the normal blinding method of digital signature based on discrete logarithm, we proved that a normal ElGamal signature scheme can't be blinded, and a blind signature based on improved scheme is proposed, at the same time through the analyzing of original design, a proxy blind signature is proposed which is base on improved blind signature, and the validity and security of these schemes is proved.