Some New Algorithms Of The Application On Chaotic Security Communication And Chaotic Control

This dissertation mainly focuses on some new algorithms of the application on chaotic security communication and chaotic control. Fields related includes chaotic cipher for image encryption, chaos-based digital modulation and chaotic control of nonlinear systems.Firstly, the brief history and its applications of chaos theory is reviewed. The basic theory and research methods are introduced. The characteristics of chaos systems are summarized. The ways toward chaos are briefly analyzed. Some common definitions of chaos are given. Some chaotic system, such as Logistic mapping, Henon mapping, Lorenz system, Rossler system and Chen system are briefly introduced. In chapter 3, the progress of the applications of chaotic communication is discussed. In chapter 4, two new image encryption schemes are presented, one is based on DES algorithm and chaotic encryption and the other scheme combines chaotic map with DES algorithm. The simulation results are given. In chapter5, chaotic modulation techniques are studied. After a brief introduction of chaotic masking, chaos shift keying(CSK), frequency modulated differential chaos shift keying(FM-DCSK) and quadrature chaos shift keying(QCSK) technique, a new modulation scheme-segment shift chaos shift keying (SSCSK) is proposed. The performance of SSCSK is analyzed by computer simulation. In chapter 6, some controlling chaos methods such as OGY controlling, feedback controlling and adaptive controlling are introduced first. Then a new chaotic control method based on improving the space correlation is presented. The computer simulation results are also given.The main contributions of this dissertation includes:In view of the characters of chaotic map and the deficient in DES algorithm, two new image encryption schemes are presented, one is based on DES algorithm and chaotic encryption and the other scheme combines chaotic map with DES algorithm. Theory analysis and simulation results show that the presented scheme can extend the initial key space, improve the security and anti-attack ability of the algorithm. It is more propitious to transmit image information, insure image information's security and confidentiality.A new chaotic modulation scheme-segment shift chaos shift keying (SSCSK) is presented. The simulation results show that under same signal to noise ratio the bit error rate performance of 4-ary SSCSK is similar to the DCSK. But the speed of 4-ary SSCSK is twice as that of DCSK on the condition of the same chaotic chip length.A new chaotic control method based on improving the space correlation is presented. As examples, the Henon discrete chaotic system and the four-order Chua's circuit is studied numerically. The simulation results show that by improving the space correlation between chaotic signals, the chaotic dynamic systems can be controlled to converge rapidly to its equilibrium point or to the multi-periodic orbits.