Research On Certificateless Group Signature Scheme And Their Application

With the development of the Internet,information security has received more and more attention,and digital signature technology provides a guarantee for safe and reliable information transmission.At the same time,according to different application scenarios,digital signature technologies with various properties are proposed.The certificateless signature system can well solve the problem of complete secret key escrow.The group signature scheme can be applied to organized groups.Signature schemes also have good applications in electronic cash systems.So this thesis studies and analyzes the certificateless signature scheme,group signature scheme and certificateless group signature scheme and its application in electronic cash.And the details are as follow :(1)In the certificateless framework,we propose an efficient pair-free signature scheme.The security and unforgeability of the scheme is proved under the assumption that the ECDLP problem is difficult.Through the efficiency analysis,it is found that the computing cost is low,therefore,the scheme can be deployed on devices with limited resources,limited computing power,small storage space and low communication network bandwidth.(2)According to Chinese Remainder Theorem,we propose an efficient group blind signature scheme with forward security,and its security is proved under the random oracle model.At the same time,the user's private key is updated through the key update algorithm,so that the scheme has forward security.Through the efficiency analysis,it can be seen that the signature length is short and the communication efficiency is high.(3)According to the idea of certificateless cryptosystem and group signature,we propose two certificateless group signature schemes.The first scheme is a certificateless group signature scheme based on elliptic curve without pairing is proposed.The process of adding,signing,verifying and revoking group members can be realized only through simple elliptic curve multiplication and synchronization factor technology,which shortens the length of the signature and improves the efficiency of the signature.The second scheme is a forwardsecure certificateless group signature scheme based on the design idea of the ACJT group signature scheme is proposed,which is shorter than the ACJT signature and requires less computation,thus improving the efficiency of the group signature,At the same time,the user's private key is updated through the key update algorithm,so that the scheme has forward security.Then,according to the group signature scheme and the switchable association ring signature scheme,a multi-bank electronic cash system that can be transferred and offline is designed.The system manages multiple banks simultaneously through the group signature system,and ensures the unconditional anonymity of consumers through the ring signature system.and check the electronic cash flow through the public ledger.The system inherits the security,anonymity,and efficiency of group signatures and ring signatures,and at the same time realizes practical properties such as offlineness,unforgeability,anti-double spending,and transferability.