Study On Methods Of Secrecy Communication Based On Chaos

With the rapid development of the computer technology, information technology and communication technology, the problem of the information or secret problem has more and more attracted people's attention. Secrecy communication becomes a new researching focus in some fields of science. Chaotic motion is a complex nonlinear motion, which widely exists in the nature, such as physics, chemistry, biology, sociology and some other fields. Chaotic signals are ergodic, aperiodic, uncorrelated, board band and noise-like. These are properties that coincide with requirements for signals applied in communication systems, in particular for secrecy communications. Therefore, there can be observed an ongoing and growing research interest.The main content of this paper contains the analysis of the synchronization of continues-time chaotic dynamical system and it's application on secrecy communication. The synchronization of the two chaotic systems can be attained by linear multivariable feedback control algorithm or single variable feedback control algorithm for the idiographic chaos matrix. The corresponding chaotic secrecy communication system can be realized by chaotic masking, chaotic keying or system identification. The main contributions are as following:1. Study on chaotic synchronization based on linear multivariable feedback control algorithm. We took Genesio chaotic model as example, the feedback coefficient of the error matrix could be attained by Lyapunov stability theory. We presented the simulation figure of the system error when the initial states of the driving system and responding system were repugnant and then analysed the trait of the method.2. Study on chaotic synchronization based on linear single variable feedback control algorithm for the particular chaotic model. On the one hand, it has more remarkable advantage than multivariable feedback algorithm when facing to the application, on the other hand, less information may bring more complex control algorithm when refer to the algorithm research. So, we must take the corresponding synchronization algorithm to the idiographic chaotic model. We took Genesio chaotic matrix as model, the synchronization controller was designed and finally realized the chaotic synchronization.3. Study on chaotic synchronization of time lag chaotic model. In order to improve the security of the chaotic secrecy communications, we should choose the chaotic model with more complex state. General speaking, superchaotic system has complicated state(such as Rossler system), however, the complex chaotic model may usually bring us the difficulty. Therefore, we introduced time lag chaotic model which had simple model but complex state. We introduced double time lag to Lorenz system's different states. We firstly guaranteed that the system was in chaotic state, then applied the feedback synchronization to the model.4. Study on experiment of chaotic masking secrecy communication based on the linear single variable feedback control algorithm. We introduced single variable feedback algorithm to realize Genesio chaotic matrix's synchronization on the basis of the quondam chaotic masking method. Synthetical signal was introduced to the chaotic driving port, so the useful signal could be syncretized to the chaotic signal so as to improve the security to resist being decrypted on the basis of realizing the synchronization encrypt. In order to simulate the actual channel, white yawp was added to the transmission channel. The result of the experiment proved that the project was good in signal renewing, feasibility and anti-jamming.5. An experiment of time lag chaotic model's chaotic keying secrecy communication. We put forward the method and solved the problem of signal distortion. In allusion to the shortcomings to be attacked, we took two measures to improve the project: firstly, transformed the system so as to improve its sensitivity to the parameter, then the project could prevent to be attacked by the generalized synchronization technique, secondly, nonlinearized the chaotic signal in the channel in order to thorough avoid attacked by the anticipating technique. After ameliorating, we improved the performance of the system in some aspects.6. An experiment of chaotic secrecy communication based on system identification method. Investigation on chaotic secrcy communication not based on synchronization can exploit the field of the chaotic communication. In the end of the paper we discussed the system identification method applied to Lorenz system's secrecy communication. The signal was modulated in the parameter of the chaotic system, in the decrypt port, the signal was demodulated by the identified parameter. The project could be realized simply and the decrypt result was very good.