Analysis And Design Of Certificateless Signcryption Scheme

The relationship between the Internet and people's daily life is becoming more and more closely,and cryptography technology becomes more and more important.In the cryptography technology,in order to send and receive messages safely,the traditional method has two processes.First,the message is signed,then encrypt the message.Encryption guarantees the confidentiality of information,Signature guarantees integrity,authentication and non repudiation.But the traditional method of computing and communication is very high,and the efficiency is relatively low.Certificateless technology can be implemented in a logic step,Which effectively improves the computing efficiency and communication cost,So it has received much attention.The certificateless signcryption overcomes the problem of certificate management in traditional public key infrastructure and key escrow problem based on identity public key cryptography.So the certificateless signcryption become a hot research in recently years.This paper is fouced on the research of the certificateless signcryption The specific contents are as follows:(1)Analyze and point out the problems existing in the original scheme,and then propose a certificateless signcryption under the random oracle model,(2)An effective combination of the identity-based signcryption technology and the certificateless signcryption technology,a certificateless signcryption scheme which under the standard mode is designed.This article mainly carries on the analysis and research on certificateless signcryption scheme.The main results are as follows:(1)The analysis of the Jing and X-WJ's certificateless signcryption scheme without the bilinear pairing are carried out,respectively.Find that Jing's scheme does not resist Type 1 enemy attack,moreover does not meet the confidentiality,authentication and unforgeability,this paper aiming at these problems,analyze the causes.It is found that the X-WJ's scheme has a lot of modular power operation in signcryption and unsigncryption process,which leads to the computation efficiency is not high,and the security of the scheme is proved to be not the standard proof method.In this paper,we start with the problem of the two schemes,and construct a secure,efficient certificateless signcryption without pairing under the random oracle model.(2)The S.Sharmila's based on identity signcryption technology and Cheng's certificateless signcryption technology combining,design a more secure and efficient certificateless signcryption scheme.Due to the ciphertext can be derived from the known equtions,so sender and ciphertext integrity and effectiveness are verfied by anyone.it is precisely because of the nature of the Public Ciphertext Verifiability.So it is more secure.and the scheme has smaller key length and the length of ciphertext than the S.Sharmila's.So the operation is more efficient.At the same time,the security proof of the standard model is given by using the theory of provably secure.