The Study Of The Group Signature

With the development of computer network and communication technology, ordinary digital signatures can not meet the requirements of the variety of electronic signatures. Some digital signatures with special characters to meet special needs become an important direction of the research. Group signature is one kind of these signatures which allow group members to sign a document on behalf of the group and provide the signer with anonymity. In the case of dispute, group manager can open the signature and trace the identity of the signer. Owing to the above characters, group signature is widely used in e-commerce and e-government.To begin with, taking the BBS short group signature for example, we analyze traditional construction method of group signature and point that it has some inadequacies. Using zero-knowledge proof makes the signature low efficiency and long length. It is also difficult to convert an ordinary signature into a group signature. At the same time, the join and the revocation of group members become very complex. Secondly, we propose a simple and efficient construction method of group signature in which the group manager is seperated into two parts. One is responsible for the management of the group members and the distribution of the key. Another is used to tace the group signature. Thirdly, we use the proposed construction method in the BLS short signature and get a new short group signature gradually. Finally, we analyse the new scheme. Results of security analysis show that the scheme is simple and efficient. It can meet all the security requirements of a group signature and have many good characters such as short length, easy to trace the signature and so on.All the signatures discussed in this paper are based on bilinear pairings. Bilinear pairing is the focus of cryptography research and an important tool of construting digital signature in recent years. It can be derived from Weil pair or Tate pair on the supersingular elliptic curve. Digital signatures constructed by bilinear pairings have the advantages of simple structure, short length and high efficiency.