Study On Provably Secure Certificateless Signcryption

With the development of information technology, the Internet has been involved in all aspects of today's society. Information technology has brought great convenience to people's lives, but we also worried about the its security. Network is a big and unknown environment, many thing in which are insecurity. Security needs had promoted the development of information security, and cryptography is a basis of information security. For the past few years, cryptography knowledge has been great developed, and information security technology has also become increasingly diversed. The state investment in network security is also growing. The most important thing is that people's safety awareness is also increasing. As a result, cryptography research have become an important subject.Cryptography's development has gone through a long period of time. After the concept of public-key cryptosystem was proposed, there are many excellent algorithms are designed. Certificateless public key cryptosystem is a new concept, it avoids the problem of complex certificate management and key escrow problem of conventional public key cryptosystem, and has a higher security. Signcryption is a new cryptographic primitive, compared with the "first signature then encryption" scheme, has a higher efficiency. Based on certificateless signcryption, this paper spent a lot of time and energy to study the short signcryption and instant message signcryption. As a result, this paper specifically includes the following parts.(1) By studying the knowledge of standard model, this paper proposed a highly efficient signcryption scheme with the use of bilinear pairings and BLS short signature. Compared with other schemes, the algorithm of this paper performed better in the aspect of calculating amount, parameters number and efficiency. Thus, in some resource-constrained network environments, the scheme can achieve better usability.(2) By studying the knowledge of instant message communication, this paper proposed a signcryption scheme with the use of bilinear pairings base on certificateless public key cryptography too. This scheme can be applied to real-time instant communication system. Experimental results and analysis show that the signcryption scheme meet the needs of instant messaging systems in complexity and security aspects. This scheme has high efficiency but low resources demand, while it achieves the message encryption, authentication and other security requirements. Additionally it also can resist the Known session-specific temporary information attack. The most important thing is that the program's run-time can be controlled within 150 milliseconds.