Research And Design Of Group Signature Scheme With Fast Revocation

With the rapid development of computer and network technology, the increasingly popular Internet provides us with tremendous economic benefits and convenience of life, but also brings lots of problems of information security, such as the disclosure of personal privacy information, trade secrets and military information, the alteration and the forgery and other security threats. Therefore, the digital signature technology with the features of non-repudiation, data integrity and authentication plays an important role in information security and is widely used in commercial, financial, military and other fields.A digital signature is an electronic form of thesis signatures in reality, which is often transmitted with the messages in the communication network and can help people to confirm whether the message signed by the legitimate sender, as well as to determine the integrity of the message. With the rapid development of computer and communication technology, the signatures become the focus of research, as an important member of a special digital signature, group signature has also been a high priority. In the group signature system, a legal group member can sign on behalf of the group, the recipient can only confirm that the signature is signed by the one of the group members but cannot confirm the identity of the signer. When necessary, such as the signature information being reported, the group administrator can open the signature to obtain the true identity of the signer can trace the malicious members. Because of these characteristics, the group signature is widely used in electronic voting, electronic bidding, and many other e-government, business activities. Therefore, the research and design of efficient and secure group signature schemes has a great practical value.Since demand of the practical application scenarios of group signature, group members tend to be dynamic join and left, which requires group signature not only to ensure basic security, the low cost of signing and verification, but also to meet a highly efficient, flexible membership revocation process. Although many group signature schemes have been proposed, but most schemes have not taken the above requirements into account, in particular, how to achieve efficient and flexible revocation of group members is an important question. In addition, many group signature schemes are still not satisfied non-correlated. Therefore, the main research direction of this thesis is to design the group signature schemes which could achieve the no-relation and efficient membership revocation.The main research work is as follows:Firstly, this thesis describes the present situation of group signature and analyzes main flaws of the existing group signature schemes.Secondly, this thesis analyzes the group signature scheme by Chen Ze-wen based on Chinese remainder theorem and improves it. This thesis combines Chen’s scheme with the notion of complete subtree method in the subset cover framework to achieve non-relation without a third party. In addition, this scheme can provide joining or revoking safely and quickly for each member without changing other members’private key, and also resist against authority trap attacks by changing the key distribution strategy. Then, this thesis analyzes the security and efficiency of our scheme, and comparison results suggest that the scheme not only has the characteristics of no-relation, but also can resist authority trap attack, conspiracy attacks and forgery attack. It also suggests that our scheme has some advantages over the existing schemes.Thirdly, as the group signature scheme of Camenisch-Stadler doesn’t realize the membership revocation and lacks the security on against conspiracy attack, this thesis proposes an efficient group signature scheme with fast revocation and against conspiracy attack. The scheme contains two programs that combining with the complete subtree method and the subset difference method in the subset cover framework. Two programs both have advantages in computing and storage cost, and adapt to different signature scene. Also, they can provide secure and fast joining or revoking for each member without changing other members’private key. Meanwhile, this scheme asks for a knowledge signature while registering, which realizes coalition resistance. It is shown that the scheme not only has the characteristics of anonymity and no-relation, but also can resist conspiracy attacks, forgery attack and authority trap attack. As for efficiency, the scheme’complexity of signature and computation is at constant level, with slightly increase of the length of group members’certificates complete. The comparison with the existing schemes suggests that our scheme has some advantages on the whole overhead.Finally, this thesis analyzes and summarizes the key issues that still exist in group signature scheme, and points out the future research topics.