Research Of Technology Of Proxy Signature With Fast Revocation

In modern society, with rapidly development and application of network, people pay more attention to the information security problem.The concept of "digital signature" was firstly proposed in W.Diffie and M.Hellman’s paper,""New directoins in Cryptography". Digital signatures, one of the most important components of cryptography, can protect the integrity, authcnticity and undeniability of information. Base on different applications, produced all kinds of special digital signatures. It makes digital signatures be used widely and deeply in practice。In this thesis, we discussed some classical proxy signatures and analyze their security in details. KPW’s proxy signature had the feature of partial delegation and delegation with warrant. It makes an original signer can control the delegation power of the proxy signer. But, proxy signature schemes based on difficulty of discrete logarithm problem. Zhang ning’s proxy signature schemes based on elliptic curve can’t be revoked.Combineing with both of advantage,new proxy signature are proposed. And then, the security of the improved schemes is proved. It is based on the elliptic curve cryptosystem whose security refers to the discrete logarithm problem (DLP) in the group of rational points of elliptic curve over the finite field. In comparision to similar schemes based on the RSA or DSS systems our solution requires application of significantly shorter cryptographic keys. The scheme is relatively simple in construction, has the property of strong unforgeability, strong identiablility, strong undeniablility, fast revocation.The thesis summarizes Identity-based encryptions and proxy signature’s developing status and research results, on contrasting Identity-based cryptosystem with certificate-based cryptosystem, the summary analyzes typical Identity-based encryptions and signatures on secrutity models and design methods.Secondly, introduce and analyze a proxy signature schemes based on identity, and improve the schemes to conquer the disadvantage and keep higher efficiency in conspiracy attack.