Abstract: Through a security analysis of a certificateless forward security proxy blind signature scheme proposed by reference [8],this paper points out that its scheme cannot resist malicious and negative KGC public key replacement attacks,and the scheme does not satisfy non-repudiation.In view of the above problems,an improved scheme is proposed to improve the user key generation method.The one-way hash function is used to embed the user public key into part of the private key,thereby restricting the part of the private key generated by KGC,so that the adversary cannot forge Authorize by signing the legal key to impersonate the original signer.In the proxy blind signature phase,the secret value of the message owner replaces a blinding factor,which not only reduces the amount of calculation,but also the message owner cannot deny that the message was provided.Security analysis shows that the improved scheme can resist malicious and passive KGC public key replacement attacks and satisfy non-repudiation.The efficiency analysis shows that the improved scheme is more efficient than the original scheme.

Key words: Certificateless cryptosystem, Digital signature, Forward security, Non-repudiation, Proxy blind signature, Public-key replacement attack, Strong blindness