Group Signature Scheme And Its Properties

With the development of computer networks, more and more people use the Internet to transmit information. Therefore, people pay more attention to the issue of information security and cryptography. Cryptography has been greatly developed in the last century, especially the emergence of public key cryptography makes cryptography is more widely used. An important application of public key cryptography is the digital signature. The digital signature is stored in electronic form, and can be transmitted through the network. Compared with the handwritten signature, a digital signature is faster and more convenient. Digital signature has a wide range of applications in the commercial, military and other aspects, so people attach great importance to the research and application of digital signature.Group signature is an important digital signature. The members in the group can generate a valid signature on behalf of the group, but not to expose the identity of the group members. In case of dispute, the group manager can reveal the signer’s identity. Because of group signature with the above characteristics, it has important applications in electronic voting, electronic auctions and other occasions. In recent years, people have been proposed many group signature schemes, but the efficient revocation of a group signature scheme is still a very important issue. In addition, many group signature schemes do not have unlinkability. This thesis mainly studies group signature scheme and its efficient revocation and unlinkability. The main results of this thesis are as follows:1. Analysis of a group signature scheme based on Chinese remainder theorem, it shows that any member of a group or a group member has been revoked can completely break the scheme. Aiming at these flaws, this paper puts forward an improved scheme. Through analysis towards the new scheme, it is shows that the new scheme can effectively revoked, and the efficiency is basically same with the original scheme. Moreover, the new scheme has unforgeability, exculpability and coalition-resistant.2. Analysis of a group signature scheme based on the discrete logarithm. Two attacks of the signature scheme show that the scheme does not have unforgeability and unlinkability. 3. Analysis of a group signature scheme with efficient revocation, it shows that the scheme does not have anonymity and unlinkability. Aiming at these flaws, this paper puts forward an improved scheme.