Study Of Chaos Synchronization And Its Application In Image Secure Communication

Chaotic behavior is an interesting phenomenon appearing in nonlinear systems,and it has been received more and more attentions in the literature during the last threedecades. A chaotic system is a nonlinear deterministic system that shows complex andunpredictable behavior. The sensitivity to the initial conditions is the prominent char-acteristics of chaotic systems, and this makes the problem of chaotic synchronizationmuch more important. Nowadays, The chaos synchronization methods have been madegood use of in the field of secure communication. The present paper discuss the chaossynchronization methods and their application to secure communication. The mainresults are expressed as follow:1. This paper introduced systemalically basic concepts of chaos:the denifition ofchaos, feature of chaos, critertion rule and typical of chaos system. Furthermore, thedevelopment of chaos synchronization, denifition and four kinds of chaos synchroniza-tion methods is presentend.2. Synchronization method of chaos systems have been studied in detail. (1) Toadaptively synchronize chaotic system and two di?erent chaotic system with uncertainparameters, we proposed a parametric adaptive control method, an adaptive controllerand the adaptation laws. Based on Lyapunov stability theory,we show that adaptivecontroller and aadaptation laws can make response system and drive system with dif-ferent initial values asymptotically synchronization.(2) Based on states linearizationtheory of nonlinear system, a new design method of controller is discussed to syn-chornize chaotic system. Through coordinate transformation, the driver system andthe repons system are transformed into canonical form systems, and then in term oftwo canonical form system, the state error equation is constructed. By pole assignmentof linear system, a feedback controller is developed.Then full states of the two chaoticsystems are synchronized.(3) The characteristics of unified and liu chaotic system areanalyzed and a observer-based synchronization mothed is put forward. First, state ofdriver system was reconstructed, then by pole of assignment,the states of two chaoticsytem was asymptotically synchronized.3. Chaos synchronization and its application to secure communication is studied.(1)Based on the feaback linearization method of unified chaos system, we realize se-cure communication of chaos masking. (2) Based on observer synchronization methodof unified chaos system, image secure communication of scrambling image pixel isconsidered. (3) Based on observer synchronization design method, an image securecommunication of double scramble for Liu chaotic system is realized.