Design And Application Of Group Blind Signature Schemes With Membership Revocation

Group Signature is a special kind of digital signature system, each member of the group can represent anonymously the entire group for signature. Group blind signature scheme is a blind and special group signature scheme, has important applications in e-commerce and e-government.Towarde the question of the revocation of the members, combining the blind signature and knowledge signature technology, considerating from the security and the efficiency, two group blind signature schemes with members revocability are designed. Moreover, applying the design method of the above-mentioned group blind signature, a multi-bank electronic cash system with members revocability is designed.Firstly, considerating from the security, a goup blind signature scheme with members revocability and unlinkability is designed. Based on C. Popescu's group blind signature scheme, combining the idea of Chen Zewen about the membership revocation, the scheme reduces the two knowledge proofs of the original scheme to one, and shorts the length of the signature. At the same time, the program improves the linkability of C. Popescu's group blind signature scheme, makes the signatures not to be linked.Secondly, considerating from the efficiency, a new and efficient group blind signature scheme with members revocability is presented.Based on the ACJT group signature scheme, using the new revocation approach of verifing whether the prime number of a member certificate is a factor of the verified public key, combining the blind signature technology, another new group blind signature scheme with members revocability is proposed. The size of the verified public key only depends on the product of a random number and the prime numbers of the legal group members, Independenting on the numbers of the members revocated. To increase or revocate a member, the group manager updates the group public key only by one multiplication or division operation, Compared to the first scheme, the processes of signature and verification are simpler, the length of the signature becomes shorter obviously. So the efficiency is higher.Finally, applying the method of the goup blind signature scheme with membership revocation above, a multi-bank e-cash protocol with members revocability is designed. On the basis of fair multi-bank e-cash model, each part of the protocol is fully described. Then the security of the protocol is analyzed.