Research On Dynamic Threshold Signature Based On CRT And Its Application

Computer networks not only bring lots of convenience to us,but bring new challenges,such as information tampering,data leakage,identity counterfeiting,and so on.How to effectively ensure the security of the information has become an important focus in the field of computer network science.As one of the important part of cryptography,secret sharing can disperse management power of the key,solve security problems caused by loss or damage of the key,and play an important role in digital signature,identity authentication,access control and other fields.Mobile adversary attack means that after an attacker cracks a member's share,the attacker transfers the attack target to another member,and eventually the attacker can crack enough member's share in a limited time to get the secret.Dynamic secret sharing allows members to update secret shares periodically,which provides an effective method to resist mobile attacks.The research background of secret sharing and the current research status are presented in this dissertation.In succession,several classic secret sharing schemes are discussed.The threshold secret sharing based on the CRT and the dynamic threshold signature scheme are studied.On this basis,a dynamic threshold signature scheme based on the CRT is proposed,the effectiveness and the security of the scheme are analysed,and the correctness is verified by examples and comparison experiments.There are some features of the scheme as follows:(1)The member's private key can be dynamically updated.During the update process,the private key of the upper cycle will not be exposed.The group private key is contant to ensure the new signature's validity.The scheme can resist the mobile attacks effectively,which improves the security and robustness of the system.(2)The original members can assist the new member to produce the private key when any original member can not get it,unless all of the original member collude.In the join process,the original member's private keys and group private key will not be exposed,which improves the security of the system and ensures the reusablilty of the group private key.(3)The scheme is based on the CRT,which has a higher time efficiency compared with the scheme based on Lagrange interpolation theorem.Finally,the scheme is applied to the large-scale payment of online bank,and a large payment prototype system is designed and implemented,which provides a feasible way to ensure the safety of bank's large payment.