Research Of Certificate-based Group Signature Scheme

With the continuous development of communication technology and computer network technology, the world is becoming an information society. Tremendous changes have been brought to modern people's production and life. Although it brings convenience to modern lives, some new problems has occurred to us with information security becoming a prominent issue. Digital signature is an important method to solve the problem. As an important direction in digital signature research, it can meet the specific requirement in some cases such as electronic payments, electronic auctions and electronic voting etc. Exiting group signature schemes more or less have some problems. For example, the group signatures of knowledge scheme are ineffective, the identity-based group signature schemes always have the key-escrow problem, and the certificateless group signatures are weak to the public key replacement attack.These problem above mainly comes from the problem of used signature algorithm or public-key cryptography themselves. In the thesis, a certificate-based group signature scheme was proposed on the combination of certificate-based signature and group signature. The main works of the thesis are as follows:(1) According to the definition of group signature and the safety requirements, combining of certificate-based signature with group signature. The interactive process of the scheme was given. And the overall framework of the certificate-based group signature scheme was given, as well as the respective functional design of the nine parts in the overall framework. Then the nine parts were divided into four modules, which include the initialization, the join of group members, the group signature and the revocation of group members.(2) The existing problems in the certificate-based signature scheme using the bilinear or discrete logarithm were analyzed, as well as the advantages of the elliptic curve cryptography compared with them. Then a certificate-based signature scheme using the elliptic curve cryptography was designed which is the core of signature and verification of the certificate-based signature scheme. The comparison of the security and efficiency of the certificate-based signature scheme was carried out.(3) Based on the analysis of the membership join schemes of the two group signature, a certificate-based membership join scheme of group signature was designed. The information exchange in the scheme can be transmitted on the public channel after the encryption of key information, while the identity-based group signature and certificateless group signature need the security channel. The practicability of the certificate-based group signature scheme was improved. At the same time, after analyzing the revocation scheme of the existing group members, a group member revocation scheme was given.(4) On the basis of the above research, the thesis gave a detailed group signature scheme. The security and efficiency of the scheme were analyzed, and the functional tests were carried out. The results show that the proposed certificate-based group signature scheme can not only guarantee the security but also improve the efficiency and applicability of group signature.