Research Group Blind Signature Electronic Cash System And Multi-bank

As the electronic simulation of the traditional handwritten signature scheme, digital signature scheme serves as a kind of authentication mechanism to ensure the origin and integrity of messages just like the traditional handwritten signature. It was proposed as a new cryptography application branch with the establishment of the public-key crypto system.The group signature is a kind of special signature scheme which allows one member of a group to sign a message on behalf of the whole group while the blind signature scheme allows one to sign a message without knowing the content of the message. The group blind signature is a combination of the group signature and the blind signature. The regular way to construct a group blind signature scheme is to add blind signature features onto a group signature scheme. In this thesis a new group blind signature scheme was constructed based on the BLS short signature scheme, the dynamic group signature model proposed by Bellare and the blindness algorithm for a signature scheme proposed by Boldyreva. The new group blind signature scheme has the property of adding and revoking group members dynamically besides the standard properties of a group blind signature scheme and also the signature can be generated via smaller computation complexity and has a shorter length.Electronic cash is electronic simulation of the traditional money that in nature is a serial of encrypted data and can be transferred through communication network. As a significant solution of electronic payment, electronic cash has been paid constant attention since the rise of e-commerce. One of the technological bases is digital signature scheme especially the group blind signature for its unique properties that the identity of the signer is anonymous and the signature can be generated without the signer knowing the content of the message. In the latter part of this thesis a new electronic cash system with multiple banks was constructed based on the group blind signature proposed earlier which is off-line that means banks do not have to participate in every transaction and sellers could sell goods to customers first and collect the received electronic cash and deposit it to banks in the future and fair that means the customers can be traced.