Research On Multistage Chaotic Synchronization System For Secure Communications

Recently, chaotic secure communication has received ever increasing attention. These chaotic characters of sensitive dependence on initial conditions and random-like behavior make the chaos signal be fit for applying in secure communication. Now most of the chaos-based secure communications are based on two synchronize chaotic systems. The thesis mainly focuses on the chaotic synchronization of three chaotic systems. Furthermore, we propose a multistage chaotic synchronization system for secure communications. In this dissertation, the main contributions are as follows:1,The definition of chaotic synchronization and the current development of chaotic secure communication is mentioned. Meanwhile, the writing arrangements are given.2,Based on the Lorenz,Rossler,Chen systems and Lorerz,Rossler,Chen hyperchaotic systems, chaos synchronization scheme of three identical and different structures chaotic systems are investigated. Several synchronization schemes of three identical and different structures chaotic systems are proposed:①The adaptive synchronization method of three unidirectional (bidirectional)coupled identical systems is proposed by means of adaptive feedback coefficients or adaptive feedback gain equations.②By designing adaptive controls, we propose synchronization schemes of three identical or three different structures chaotic systems by means of nonlinear control method.3,Based on the Lyapunov stability theorem, a new type of chaos synchronization, general hybrid projective complete dislocated synchronization, is proposed under the framework of drive-response systems.4,Used three synchronized chaotic systems, propose a novel method of chaos encryption through chaotic masking. By the transmission of continuous signals and discrete signals, the efficiency of the new communication system could be demonstrated. In consideration of noise interfering, the results of encoding and decoding are simulated and analyzed under the noise resistance. Analyzes the characteristics of noise and then presents a de-noising method using wavelet transform.5,A new secure communication method is proposed based on general hybrid projective complete dislocated synchronization. In this method, the previous partial sums of driving variable are used to mask an information signal so that it can enhance the security of signal transmission.6,Extend the method of multistage chaotic synchronization system for secure communications to four chaotic synchronization system, meanwhile, we give the security analysis for the information.