Research On Certificateless Proxy Signature Algorithm Without Bilinear Mapping

With the deployment and use of intelligent devices and intelligence networks in the Internet of things and medical systems,the ways of data collection and storage are becoming more and more diversified.Therefore,the integrity security and confidentiality of data become more and more popular.As an important security mechanism in information security,digital signature plays an important role in ensuring information integrity and non-repudiation.Certificateless signature scheme has been widely studied and applied in recent years since it can avoid the issues of certificate management and key escrow.Proxy signature is still of great significance in practice because it can authorize subordinates to exercise the right of signature.However,the existing proxy signature schemes are vulnerable to be attacked in the stage of authorization and signature since they are not bound with the identity information of the agent.This paper combines the advantages of certificateless cryptosystem and proxy signature system to design a secure and efficient certificateless proxy signature and certificateless proxy aggregate signature scheme.In this thesis,certificateless proxy signature and certificateless proxy aggregate signature schemes are deeply studied and analyzed.The key replacement attack and the proxy signer's denial attack in the existing schemes are analyzed and improved.(1)Based on the existing proxy signature schemes,a new secure and efficient certificateless proxy signature scheme without bilinear mapping is designed.In this scheme,the secret value generation algorithm is put before the partial key generation.The partial public key of the user is bound with the partial public key generated by KGC,which effectively prevents the key escrow problem and key replacement attack.In the generation of partial proxy key,the identity of the proxy signer is bound with that of the original signer,which effectively prevents the denying of proxy signer and endows the proxy signature with strong non-repudiation.The correctness and unforgeability of the algorithm are proved based on elliptic curve discrete logarithm problem in random oracle model.(2)The existing proxy aggregate signature scheme is analyzed,aiming at the security problems of key replacement attack,agent denial attack and collusion attack.Since the complexity of bilinear pair operation and reverse operation is high in some existing schemes,a new scheme of certificate free proxy aggregation signature that can resist key replacement and malicious agent denial attack is designed.Such scheme is secure and efficient and constructed without bilinear mapping.Meanwhile,the correctness,unforgeability and non-repudiation are also proved.