Chaos Synchronization And Its Application In Secure Communication

As a phenomenon found in nonlinear dynamic system, chaos is deterministic and random-like. Base upon the sensitive dependence of chaotic systems on their initial conditions, a large number of non-periodic, continuous broadband frequency spectrum, noise-like, but deterministic and reproducible signals can be generated, so chaotic technology is very useful for security communications. The detail is clarified as follows:(1)The new construction method based on traditional Logistic chaos mapping and Blowfish algorithm has been proposed. This method can generate good chaotic codes which embody the advantages of two algorithms. The digital chaotic sequence generates P arrays and S boxes as secret keys, which make the new algorithms have chaotic characteristic. It is difficult to decode this sequence. The whole algorithms have accomplished by C++.(2) Taking Liu chaotic system as the sector of a multistage chaos system. The dissertation adopts adaptive method to deduce control laws and parameter adaptive laws based on Lyapunov stability theory in the condition that the system parameters are partly unknown or all unknown. We also design the synchronization method based on state observers. At last we design a multistage synchronized system for communication. Comparing the system has no feedback with the one has feedback, We can learn that Chaotic system can mostly improve extention of the bandwidth, the characteristic of distortion and level of security.(3)Using VC++ as the basis of encryption approach for acquire wav signal. Through the encryption of ameliorative Blowfish algorithm and modulation of multistage chaotic system, the system can generate graph of wav. The API functions can acquire and broadcast wav signal and display the graph of wav.The dissertation investigates chaos synchronization and its application in secure communication, the results of these researches will be useful in the future.