Research And Design Of Special Proxy Signature

In 1996,the concept of proxy signature was first introduced by Mambo, Usuda and Okamoto and its efficient solution was given at the same time.In a proxy signature scheme,because of on business,health,resources restriction or other reasons, an original signer can delegate its signing power to a designated person,called proxy signer.The proxy signer can generate valid proxy signature of any message on behalf of the original signer.When a receiver verifies the proxy signature,he can verify both the validity of the proxy signature and the proxy warrant together.As the proxy signature is researched deeply,proxy signature have been enjoyed a considerable amount of interest in cryptograpgy.In order to apply some special cases,experts and researchers have realized proxy signature using some special signatures,such as threshold secret share, blind signature,multi-level signature,signcryption,multiple signature and Zero knowledge proof,etc.Since then,various special proxy signature schemes have been proposed,such as threshold proxy signature,multi-proxy signature,multi-level proxy signature,proxy signcryption and proxy with designated verifier,etc.At the same time, proxy signature has been applied to the e-vote,moble agent system,e-cash and griding computing,etc.Based on the existent proxy signature schemes,our research mainly focus on the application of blind signature,multi-level signature,secret sharing,self-certified public key system and signcryption in the proxy signature.Furthermore,by analyzing some existent proxy signature schemes,we show that many existing proxy signature schemes have some security weaknesses:(1) They can not satisfy strong undeniability and strong unforgeability,etc;(2) They can not resist forgery attack,public-key substitute attack and collusion attack,etc;(3) They have lower efficiency,high computational complexicity and communication overhead;(4) They have the problem of security of public key.Aiming at these problems in proxy signature schemes,we propose several secure and efficient special proxy signature schemes.Main contributions of this paper are summarized as follows:1.A new proxy blind signature scheme is proposed,which is based on the discrete alogrithem problem.The new scheme not only satisfies all properties of proxy signature should have,but also has the properties of blindness and untraceability.2.A multiple blind proxy signature scheme with message recoverary is proposed, which is based on the Nyberg-Rueppel signature.In the new scheme,the original signer cannot idengtify who generate the proxy signature,in other words,the scheme has the property of unidentifiability.3.Aiming at the multi-level proxy signature problem in practice cases,a new multi-level strong proxy blind signature scheme based on the identity system is proposed.In the new scheme,the original signer can delegate its signing capability from step to step.The new scheme is truely secure and efficient.4.By analyzing the security of H-C scheme,we show that their scheme cannot resist forgerary attack and public-key substitute attack.Furthermore,we give two methods to defeat these attacks.5.By analyzing the security of YCH scheme,we show that the scheme is not secure and cannot resist frame attack and public-key substitute attack.Then we give an improvement and propose a new nonprepondiable threshold proxy signature scheme.6.Using the merit of self-certified public-key system with high security,a new self-certified public-key multi-proxy signature scheme is proposed,which is based on the Elliptic Curve Cryptology.In the new scheme,the proxy group's private key and public key is generated by the proxy group.Under the Elliptic Curve discrete logarithm problem,the new scheme is truly secure.7.Aiming at the problem that many proxy signature schemes can not provide confidentiality,a new multi-proxy signcryption scheme with shared unsigncryption is proposed,which is based on the Elliptic Curve Cryptology.The new scheme doesn't need a security channel.