Study On Provable Secure Signcryption Scheme In The Standard Model

With the rapid development of society and the network, sending information through the network has become the modern main trend, which has hidden danger. So network communication security problem becomes one of the important problem which people pay more and more attention. Cryptography technology can realize secure communication, so the application of the modern cryptography receives wide attention.Signcryption, a highly efficient kind of the cryptographic primitive, can perform digital signature and encryption two functions in a single logical step at the same time. And, the computational cost and communication cost is much lower than the traditional signature-then-encryption approach. Compared to the standard model, the random oracle model only construct effective programs, but in reality cannot build specific instance. So how to the standard model construct a provably secure cryptography is the studies direction of contemporary mainstream.The thesis will further focus on a systematic study on design and provable safety of signcryption scheme in the standard model, and it specifically contains:(1) Under the use of bilinear pairings, based on Gu proxy signature and identity based signcryption technique, provable secure identity based proxy signicryption scheme in standard model is proposed. Firstly, the thesis gives formal definition and security model of proxy signcryption and then a specific build of the scheme. Lastly, the paper has unforgeability and confidentiality in the standard model based on the computational Diffie-Hellman assumption and decisional dilinear Diffie-Hellman assumption. The analysis shows that reduces calculational time and computational complexity and improves efficiency.(2) Combined with the idea of certificateless scheme and based on signcryption technique, a certificateless signcryption scheme in the standard model is proposed. Firstly, the thesis gives formal definition and security model of certificateless signcryption. And then gives the specific build, and finally proves that the paper has unforgeability and indistinguishable in the standard model based on the computational Diffie-Hellman assumption and decisional bilinear Diffie-Hellman assumption. The analysis shows that these schemes can ensure its security with no additional computational cost.