Research On The Key Technology Of Agent Digital Signature

With the rapid development of computer technology and communication technology, people have gradually entered into a new era of Internet. The electronic bank, e-government, Cloud computation、Big Data are booming as the products of the Internet age. However, with the ceaselessly revolution of information, security issues of Network become more and more serious. So, how to build a comprehensive and effective protection measures, how to develop more data security model to meet the needs of information age is the focus of concern. Digital signature as the key technology of cryptography in the data integrity and non-repudiation, authentication and anonymity plays an important role in such aspects and provides a good security mechanism for network communication.In1996, the proxy signature system was first proposed by Mambo, Usuda and Okamoto. Proxy signature is a digital signature with authorization mechanism. In the proxy signature system, the actual original signer who can’t attend for some reason can delegate his signing capability to the proxy who can sign messages instead of original signer. Proxy signature has been widely used in mobile communications, electronic commerce, electronic voting, etc. So far, many proxy signature schemes were put forward in succession, but some scheme had been proposed has security problems, therefore, further research of the key theory and technology of proxy digital signature has a very important theoretical significance and application value.This paper mainly studied the four kinds of proxy signature with special characteristics, and put forward my own research results from the perspective of extending the security of proxy signature.1. First of all, review the existing Shared verification (t,n) threshold multi-proxy multi-signature scheme. Point out that TYH scheme couldn’t resist forgery attack and don’t really have Shared verification, at the same time, also analyze the security of W-L-D scheme, and pointed out that their scheme does not have the private key security. According to the existing security defects, this paper proposes a new threshold multi-proxy multi-signature scheme with Shared verification, and demonstrates the security of scheme, the results show that the safety of new scheme guaranteed by RSA problem and satisfy all the security requirement of proxy signature.2. Analysis of the security flaws of Wang scheme points out that the Wang scheme can not satisfy the forward security property, in view of the serious consequences of loss of digital signature private key, this paper proposed a new forward security proxy signature by the combination of the forward secure digital signature schemes and proxy signature scheme, so as to ensure the private key lost before the proxy signature is valid. And proves the security of the new scheme.3. The type of Tan Schnorr proxy blind signature scheme is analyzed, and the pitfalls of Tan scheme had been found. In view of the defects of Tan scheme, and combined with the nature of the blind signature, an improved proxy blind signature scheme is proposed. Improvement scheme can resist the original signature and recipient’s forgery attack, and has the characteristics of Strong Blindness and revocation of the agency.