Research On Image Encryption Algorithm Based On The Lorenz Chaotic System

With the rapid development of network and information technology, information security and privacy issues have become increasingly prominent. Digital image has large amount of data, high redundancy and the adjacent pixels correlation between higher characteristic. Because traditional encryption methods are superior to the small key space and the low security defects, it is easy to be attacked. Due to its good random properties, ergodicity and long-term unpredictability, chaotic system’s high complexity is easy to realize. As the chaotic image encryption algorithm exists relatively simple structure, small key space etc, the paper designs a hybrid combining Lorenz chaotic system and other encryption algorithm. The concrete research contents are as follows:Firstly, this paper introduces the basic knowledge of chaos theory and cryptography, and analyses the domestic and foreign research present situation of the chaotic image encryption and significance of the research, describes the principle of modern cryptography system. A traditional chaotic image encryption algorithm is introduced and the simulation experiment has been carried on.Secondly, for the relatively simple structure, small key space problem of traditional encryption algorithm based on chaos system, a hybrid image encryption algorithm based on Lorenz chaotic system and Arnold transform is designd and the simulation experiments are carried out with MATLAB. The key space size and adjacent pixels correlation of the algorithm are analyzed. The experimental results and the security analysis indicate that this algorithm can achieve the goal of confusion and pixel value diffusion which cryptology requires. The algorithm has a large key space and very good anti-interference ability, and its superiority is proved.Finally, as the hybrid encryption algorithm of Lorenz chaotic system and Arnold transform is generally used only on square image encryption processing, an image encryption algorithm based on Lorenz chaotic system combined with Logistic mapping is designd and simulated in MATLAB environment.