Design And Implementation Of Image Encryption Based On Chaotic Synchronization

As a special form of movement, chaos possess the characteristics of randomness, high sensitivity to initial value, which make it show great prospect in secure communications. To obtain chaotic signal efficiently and steadily is the precondition of chaotic secure communication. In recent years, plenty of experts and scholars in the field of chaos have put forward many kinds of new models of generating chaotic signal, as well as new technologies and new methods implemented by hardware.First of all, this thesis introduces the basic definition and characteristics of chaos. Then, it takes some discussion on the relationship between cryptography and chaos. Moveover, some chaotic cipher algorithms are also presented. Furthermore, it designs a parameter adjustable Lorenz chaotic signal generator according to the Lorenz equations and its characteristics. The simulation result shows that the phase trajectory of the Lorenz signal generator is the same as a Lorenz system simulated by software, which verifies the effectiveness of the Lorenz chaotic signal generator.In addition, according to the problem of the small encryption key space when using a single chaotic map for encryption, this thesis designs a hybrid image encryption scheme based on Logistic map and Lorenz chaotic system, combined with chaos synchronization theory. The circuit simulation shows that the hybrid algorithm is an algorithm which encryption effect is better than the others. Since the hybrid scheme increase the encryption key spaces, the security of the image encryption can be improved effectively. In order to solve the problem induced by the lower speed for processing signal used computer language, this thesis applies the Lorenz chaotic signal generated on the DSP platform to image encryption, which further proves the feasibility of the scheme. The efficiency of encyption and decryption is also improved.