The Application Of Group Blind Signature In Multi-Bank Electronic Cash System

Group signature is one of the useful singnatures, by now. In all the schemes, ACJT is the best in all kinds of capabilities, as it satisfies the common security requirements. At the same time, it resisits all the attack ways. This paper reviews the requirements in special setting, then provides 3 types of group signature.First, in the electronic commerce, it needs the anonymity, when one use the electronic coin, he could not be tracing, blind signature can satisfy the security requirement, and group signature is often used in electronic bank scheme, so group blind signature can satisfy all these security requirements. With the protocal of blind bidiscrete logarithm proposed by L.Anna and R.zulfikar, this paper implements the group blind signature on the ACJT scheme.Secondly, in the electronic bank system, the group key is the core secret, once the key is leaked, the whole system will be destroyed. for the goal of reducing risk,this paper adds the concerp of forward-security to group signature. when the key in one time segment is leaked, the document signed or encrypted befor this segment can nor be destroyed. So that it greatly extends the security of the group signature scheme.At last this paper implements the multi-bank system with above schemes, remedies the limitation of forgoing schemes, and resolves the par value problem. The par value is designated by the bank, and it is binding with the signature, thus the problem of user cheating can be avoided.