Research On Identity-Based Digital Signature And Signcryption Schemes

As the deepening of the digital signature research and the rapid development of E-commerce and E-government, research on digital signatures with additional properties becomes a main research direction. In the concept of Identity-Based Encryption System, users just need know each one's Identity information such as email address and public parameters provided by Private Key Generator. Signcryption can achieve both the signature and encryption function in a logic step and is with the cost lower than common way"first signature and then encryption", thus is an ideal way to achieve information storage and transmitted secretly and verifiably.In this thesis, we discuss several Identity-Based signature and signcryption schemes with additional properties, including proxy signcryption, threshold proxy Signcryption and proxy partially blind signature. The main contributions are as follows.1. The author analyzes LI-CHEN scheme and gives three attacks to prove that the scheme does not satisfy strong unforgeability and forward security. At the same time, we propose two new schemes which can satisfy them. Furthermore, there is no secure channel needed in our schemes so they are more efficient than LI-CHEN scheme.2. The author proposes an Identity-Based threshold proxy signcryption scheme from bilinear pairings which can satisfy security, verifiability and non-deniable at the same time. The security analysis of the scheme is also proposed.3. The author introduces the concept of proxy signature and partially blind signature into Identity-Based encryption system. So we propose an Identity-Based proxy partially blind signature scheme from bilinear pairings based on Diffie-Hellman problems and Discrete Logarithm problem. The scurity analysis is also proposed.