The Research On Proxy Re-signature With Aggregate Property,Certificateless Signature And Their Applications

The requirement of information technology becomes higher and higher with the rapid development of informationization and networking. Traditional digital signature technology can not meet to people’s needs for using information technology in different scenarios. In order to solve security and authentication issues, particular digital signature technology with different functions is needed in different scenarios.In this thesis, the author discusses proxy re-signature with aggregate property based on identity and multilinear mapping and certificateless signature scheme based on identity. Proxy re-signature is used for the scenario about conversion of ciphertext, the certificateless signature is used for the scenario without certificate to ensure the authenticity of the public key and has eliminated the keyescrow problem.The main contributions are as follows.1. On the basis of an ID-based signature with unrestricted aggregation proposed by Hohenbur- ger et al., the first bidirectional ID-based proxy re-signature that admits unrestricted aggregation is offered by utilizeing the full domain hash structure from multi-linear map proposed by Hohenburger et al. In this construction, an arbitrary-sized set of signatures or re-signatures can be aggregated into a single group element, which authenticates the whole set. This scheme can be proved selectively secure under the l + n-MCDH assumption.2.Security analysis on the certificateless signature scheme presented by Pan et al. shows that the scheme is insecure against public key replacement attack and malicious KGC attack. For the two kinds of attack, detailed attack methods are given. Aiming at these problems, the scheme is improved by the modification of traditional certificateless signature algorithm sequence and the regularly update of user’s secret values in this paper. And the improved scheme also enhanced the relationship of identity informat- ion with other parameters to meet the security requirements. Its security relies on the hardness of the DL problem,CDH problem and Inverse-CDH problem. Under the random oracle model, the new scheme is proved to be secure. Furthermore, it has better overall performances and forward security than Pan et al.’s.