Threshold Proxy Signature Scheme And Its Application

In modern society, with rapidly development and application of network, people pay more attention to the information security problem. As the technology for ensuring information security, digital signature plays an important role in protecting integrality, unforgeability, undeniability and verifiability of information. Threshold signature and threshold proxy signature, which are two kinds of particular digital signatures, because of their peculiar threshold characteristic and proxy characteristic, have become one of the major subjects in the cryptography field. This thesis proposes a threshold signature scheme and a threshold proxy signature scheme which are secure and efficient. The designing of an electronic review system based on the presented threshold proxy signature scheme is introduced in the last part of the thesis.First the thesis introduces the basic knowledge of threshold signature and summarizes general problems in existing schemes. A typical threshold signature scheme is analyzed and improved from traceable, anonymous, robust, stable and nonpseudo characteristics, and a threshold signature scheme based on the discrete logarithm problem (DLP) is brought forward, which can satisfy security and performance requirements of threshold signature schemes. The applications of this scheme in electronic commerce and electronic government are discussed.Then, grounded on analyzed basic knowledge of threshold proxy signature, the thesis generalizes the security problems in existing schemes. According to the presented threshold signature scheme in the thesis and the characteristics of proxy signature schemes, a threshold proxy signature scheme based on DLP is proposed. The thesis analyzes some commconly used attacks detailedly to verify its security, including the effectual attacks of forgery attack, collusion attack and public key substitution attack etc., and compares it with an up to date threshold proxy signature scheme. It is concluded that the proposed scheme is more secure and efficient. Considering the characteristics of the elliptic curve cryptosystem and the structure of the proposed threshold proxy scheme, a scheme based on elliptic curve discrete logarithm problem (ECDLP) is come out, which makes use of the advantages of elliptic curve. The computational complexities and communication costs of the scheme are cut down, and the performance is improved.Last, based on the above scheme, an electronic review system is designed and developed, which can reduce the workload of editors and increase the automation of review systems.Meanwhile, the sensitive information is encrypted before transmitted, which enhances the security of the system.