Threshold Group Signature Scheme Based On Elliptic Curve Cryptosystem

Digital Signature, one of the important applications of public key crypto-system, can be used to protect data integrity and authenticate the identity of the sender in a message. In particular, the birth of Public Key Cryptography (PKC) opened up a broad road for the research and application of digital signatures. Group signature , whose definition was raised firstly by Chaum and Van Heyst[2] in 1991, is an important anonymous signature technology. Secret sharing provides a solution for the problem of security and storage of the secret, that was used in group signature and formed a new signature-threshold group signature.In this paper, author analyses the scheme of XXS wrote by Xiang Sheng- Xia [1] (called XXS scheme) and forms a new scheme. Separation of the key idea, which is used in secret sharing, means that administrator does not know the secret of users and users do not know the reciprocal value of threshold function. Separation of the key can defense the attack of combination and restrict the right of administrator efficiently. New scheme, which is based on the difficult solution problem of elliptic curve, can enhance security, elevate computation and save the cost of storage and transmission. Administrator can join or delete members efficiently by changing the public parameter. New scheme can reject many attacks although it is briefness.