Research And Application Of Threshold Digital Signature

As one of the core technology foundation of information security, digital signature can provide the ability to ensure the source of message and guarantee the data is not tampered. Digital signature provide the effective protection of reliability and security of information, so the digital signature is widely used in communication, stock trading, online booking and many other kinds of application. But with the development of these applications, ordinary digital signature is difficult to meet the special requirements of the applications. Various kinds of digital signature come into being. Threshold digital signature is one kind of special digital signature which has attracted wide concern of cryptology researchers because of its advantage which inherit from digital signature and the unique threshold characteristics of secret sharing. Various of threshold signature has been proposed from the concept emerge.This paper expatiates the concept, background and the last researches of threshold signature. To start from the way of system parameters come out, we divide threshold signature into two parts consist of signature which need trusted center and signature without trusted center. Then we discuss these two kinds of threshold signature. As the without trusted center threshold signature has more wider range of application, so this paper focuses on the study of no-trusted center threshold signature. Firstly this paper analyze the security of one no-trusted center threshold signature scheme, then we expatiate two typical attack on threshold signature. By summing up the defect of the scheme, this paper gives a modified scheme.Threshold signature is a kind of practical special digital signature, but the scheme which apply threshold signature into production and living is sparse. In the fifith chapter of this paper,we design a distributed time stamp system by using the improved threshold signature which gived in chapter IV. Compare to the system designed by Akira Takura, our system has higher security and stability. In the sixth chapter,we propose a method to apply the dynamic threshold signature scheme to the worm characteristic generate system. Compare with the scheme in references, this scheme need more resource of communication but this scheme improve the security of the system and providing a functional classification of worm damage.