Design And Implementation Of Chaotic Secure Communication System Based On Linux Platform

With the rapid development of the Internet, the information security issues attract extensiveattention worldwide, and how to ensure secure transmission becomes an issue deserves to be solvedurgently. Chaos is a kind of uncertain movement type which is derived from a certain nonlinearsystem. It has the characteristics of high sensitivity to initial values and random similarity, whichenables the chaotic pseudorandom sequence generated from chaotic system to be widely used in avariety of information encryption and secure communication occasions. For the sake of generatingpseudo-random sequence of good performance, that is, to enhance the security of secrecy system,this paper explores new chaotic systems. Firstly, we attempt to apply the new circuit element-TiO2memristor into construction of chaotic circuit and design a memristor-based system. In addition, anew discrete chaotic map with exponential term is implemented. Based on research of memristor-based system and the discrete map, a chaotic secure communication system on the Linux platform isproposed, implementing the voice communication and text communication. The pseudo-randomsequence generated from the above systems is used to encrypt information in order to improvesecurity of the system.The main contents of this paper are as follows:(1) Research on the fundamental theory of chaos and memristor, and derive the mathematicalmodel of TiO2memristor proposed by HP Labs. On this basis, by replacing Chua’s diode with anactive magnetic-controlled memristor, a five-order memristor-based chaotic circuit is derived from afour-order Chua’s circuit。Using MATLAB software, the dynamic characteristics are investigated,including equilibrium point, stability analysis and Lyapunov exponent. Finally, verify the chaoticsystem using DSP experimental platform. The verification result is consistent with theoreticalanalysis.(2) Logistic map is a typical discrete chaotic map, but it has defects of having only oneparameter and small parameter range under chaotic state, so we attempt to modify it. By introducingexponential term and new system parameters, the parameter range under chaotic state of the systemis enlarged. Analyze fundamental dynamic characteristics of the map, including Lyapunov exponent,bifurcation and cycle window research. Finally pseudo-random sequence is generated from the mapand NIST test of sequence is done. Characteristics analysis and NIST test results all indicate that thesequence has a better performance over Logistic map, therefore system encryption using the maphas higher security. (3) Design and implement a secure communication system on the Linux platform. Specificallyin Ubuntu environment, full-duplex voice communication is achieved by using Linux audioprogramming and multithread programming. The text and voice transmission is implemented bysocket programming based on UDP protocol. Write the user interface of the application softwareusing Qt. The pseudo-random sequence was derived from the above two systems. The encryptionscheme is one-time pad using chaotic stream cipher. The concrete implementation is XORalgorithm. The security of chaotic stream cipher system mainly depends on the complexity ofchaotic signals and just because the pseudo-random sequence possesses better characteristics, thesecurity of the system can be guaranteed. Finally, the overall performance of the communicationsystem was tested and achieved the desired results.