Study On Ring Signature Scheme And Its Application In Electronic Voting

With the fast development of the networks as well as the appearance of more and more information systems dealing with governmental affairs, commercial affairs, and even daily affairs,digital signature-a subset of public-key cryptology-is sure to be attractive for more extensive applications in the coming years. Since the idea of "digital signature" was firstly proposed by W.Diffie and M.Hellman, many digital signatures have been proposed, such as the very famous schemes of RSA, ElGamal, DSS, etc. In real-life applications, it is necessary to add some additional properties to standard signature schemes mentioned above. Accordingly, several signature schemes with special properties have been proposed, such as group signature, ring signature, blind signature, signcryption, etc. The researches over those special signature schemes mentioned above will surely contribute to the theory of information security as well as cryptology, and will be of great importance to the design of practical, secure and efficient cryptographical protocols for commercial affairs, governmental affairs, and military affairs. This dissertation mainly studies these special signatures, especially the theory of ring signature.This thesis mainly focuses on the research of ring signature schemes based on the finite field and gets some results:1. motivated by Wei's signature without random oracles, we constuct a new ring signature based on bilinear pairings, whose security relies on the q-Strong Diffie-Hellman Problem in the standard model.2. We proposed an electronic voting scheme based on anonymous communication channel using ring signature protocol and threshold pro- tocal. The identity information of honest voters can be protected unconditionally. We can also prove that the voting privacy and fairness can be realized simultaneously before the counting. Besides, we solved the "vote collision" problem.