The Analysis Of Certificateless Digital Signature

With extensive using of computer network,digital information has become the main carrier of social communication.How to better meet these requirements has become an important issue of security study.As an important branch of public key cryptosystem,digital signature can provide security and authentication for information.In this paper,we focus on the certificateless digital signature study and the certificateless aggregate signature study.In order to build a more secure signature protocol,so as to achieve a more secure authentication mechanism.Certificateless digital signature can solve the key escrow problem.Meanwhile,it can ensure the system user's public key is authentic and effective,in no need of certificate case.The following is our main research:1.We analyzes the security performance of certificateless signature scheme of Wang et al.And propose an improved scheme.In the improved scheme,we still using bilinear maps.We increases the complexity of the partial private key.So that,the attacker can not obtain the user's secret key by recomputing the user's signature and ephemeral secrets.We analyzes and proves the security of the improved scheme for public key replacement attack,the malicious KGC attack and the ESL attack.We prove that the improved scheme can resist the above attacks.2.We propose a new secure certificateless signature scheme.The signature verification of our scheme uses bilinear mapping.By using a package of the user's partial private key,the attacker can not compute the user's private key information through the signature and the ephemeral secrets.So that,the robustness of our protocol's security is improved.Our scheme is able to provide good security against the ESL attacks.The security proof for the public key replacement attack and the malicious KGC attack is provided latter.Our scheme achieves more secure and stable signature protocol.Meanwhile,it has a good application value.3.We propose a new certificateless aggregate signature scheme.The scheme uses a package of the user's partial private key and a part of the signature,so that the generated signature information can have a fixed length.At the verification stage,it can be directly authenticated by the aggregated signature.At the same time,by this package step,the scheme is able to resist the ESL attacks.For the public key replacement attacks and malicious KGC attacks,the security proof of the CDH problem based on the random oracle model is provided.