Researeh And Implementation Of Image Encryption Based On Chaotic Technology And DNA Encoding

With the rapid development of digital information and Internet technology, how to ensure the security of digital image in the process of storage and transmission caused widespread concern. Image encryption mechanism is one of the effective secret method. Due to the chaotic sequence has a high sensitivity of its initial conditions, continuous wideband and other basic features, generally, conventional encryption algorithms is difficult to meet real-time communication requirements. Chaos is a kind of deterministic random processes in nonlinear dynamics system. Irregularities in the process, the high sensitivity to initial conditions and good ergodicity makes it very suitable for image encryption.Firstly, the thesis elaborated the background and significance of the research and research status of image encryption. Secondly, it introduces basic theory of cryptography and chaos and the relationship between them. Then, a color image encryption algorithm based on Lorenz mapping and DNA sequence is proposed. Firstly, the plain image is encoded with DNA encoding and decoding rules, and then R, G, B three planes is scrambled and replaced with the use of three-dimensional map of Lorenz after DNA encoding. Finally, the image is decoded with DNA encoding and decoding rules.Then a color image encryption algorithm based on Arnold mapping, Logistic mapping and DNA sequence is presented. This algorithm uses Arnold mapping to scramble pixel position and Logistic mapping and DNA sequence to replace the pixel value and then diffuse the image with the new diffusion algorithm.Then a color image encryption algorithm based on Arnold mapping, Logistic mapping(One does superposition operation and another controls pixels do with similar DNA XOR or XNOR operation) and similar DNA sequence is raised. This algorithm uses Arnold mapping to scramble pixel position and Logistic mapping and similar DNA sequence to replace the pixel value and then diffuse the image with the new diffusion algorithm.This thesis carries out safety analysis of the algorithm from the sensitivity of the key, statistical characteristics, sensitivity of the plaintext and other aspects. Simulation results show that the encryption algorithm has good encryption effect, to a certain extent, it can resist brute-force attack, statistical attack and differential attacks.