Study On Special Properties Signcryption System

With the rapid development of society and the network, sending information through thenetwork has become the modern main trend, network communication security problembecomes one of the important problem which people pay more and more attention.Cryptography technology is the most important means to realize secure communication, sothe application of the modern cryptography receives wide attention.Signcryption, a special kind of the cryptographic technique, can perform digital signatureandencryption two functions in a single logical step at the same time. And, the computational cost andcommunication cost is much lower than the traditional cryptographic technique. Thistechnology is widely used in communications security agreement. In the random oracle modelcan build efficient solution, but it is as an ideal model of completely random. It cannot beachieved and constructed in reality. So how to in the standard model construct a provablysecure signcryption scheme is the studies direction of contemporary mainstream.The thesis will further focus on a systematic study on the cipher system and provablesafety of provably secure signcryption scheme in the standard model, it specifically contains:(1) Under the use of bilinear pairings, based on Waters signature and universaldesignated verifier signature, provably secure universal designated verifier signcryptionscheme in standard model is proposed. Firstly, the thesis gives formal definition and securitymodel of universal designated verifier signcryption and then a specific build of the scheme,lastly proves the security of the scheme in the standard model based on the computationalDiffie-Hellman assumption. The analysis shows that the proposed scheme is able to meet theconfidentiality, unforgeability and non-transferability. And compared to the existing schemes,reduces calculation time and computational complexity, improves efficiency.(2) Combined with the idea of identity-based sanitizable signature and signcryption, andbased on Waters signature technology, an identity-based sanitizable signcryption scheme inthe standard model is proposed. Firstly, the thesis gives formal definition and security modelof sanitizable signcryption, and then gives the specific build, and finally proves the security ofthe scheme in the standard model based on the computational Diffie-Hellman assumption. The analysis shows that the proposed scheme satisfies security requirements of theidentity-based sanitizable signcryption, and is of strong practical value.