An Analyzed And Improved Threshold Group Signature Scheme With A Privilege Set

With the development and popularization of the information technology, traditional handwritten signature or seal is no longer appropriate in the political, military, economy and daily life. Computer communication and e-government, e-commerce is widely used, and then digital information storage, transmission in our daily life play an increasingly essential role. However, it’s inevitable to encounter some malicious attacker for various purposes, such as replace and forge the digital signal in the process of communication, or just pretend to be legitimate to communicate and transmit information.Therefore, we need to develop new effective information security technologies to identify and determine the authenticity of received digital information, thus make the computer communication, e-government, e-commerce, etc go smoothly. The digital signature technology is produced in such an environment.Digital signature is a classical application of the public key technique. It can guarantee the authenticity of information, the integrity of the data, the verifiability of the sender identity, the nonrepudiation, and the impossibility of forging. Along with the development of The Times, the study of digital signatures also unceasingly thoroughly, from the general digital signature to digital signature technology which meets with special properties, specific needs and special functions, such as threshold group signature, etc.Threshold group signature is one of the important directions in digital signature research, which is a generalization of the group signature. The main idea is the introduction of secret sharing in the group signature. By the definition of the secret sharing, we can know that the threshold group signature has the security features of risk sharing, distribution of power, trust sharing.The group-oriented threshold signature is a further deepening of threshold group signature, and it is more practical in the recent market. On the basis of the research on the threshold signature, the thesis mainly studies the problem of efficiency and security of Privilege set threshold group signature scheme, the main results are as follows:1. We analyze the threshold group signature scheme with a privilege set designed by Wei Dong Chen and Deng guo Feng, and point out problems of Chen’s scheme, such as the generation of the group signature, KAC fakery of the signature, and signature event tracking.2. For the defects of Chen-Feng’s scheme, we put forward an improved existing privilege set threshold group signature scheme. And the correctness and safety of the new scheme are analyzed, and proved that the new signature scheme can generate the correct group signature, improved the security of the original plan, make it more practical.