Design And Implementation Of Image Encryption Algorithm Based On Chaotic Systems

Nowadays, along with the dramatic development of intelligent devices, internet of things(IOT) and high definition(HD) multimedia technology, the transmission of bulk data in our life, such as document, audio, video, especially image information seriously depends on the network. Image has been developed as an indispensable means of communication in our daily life for its vivid, simple and intuitive properties. However, the security of the network has not reached an absolute level, so the transmission of the image is still not safe enough. A large number of news which has been exposured is rather common to all, so there is no doubt that the exposured information will have an immeasurable impact on individuals, businesses and even the country. So researching and exploring a safe, reliable and practical image encryption method has aroused people's attention.Chaotic system is a nonlinear system with the complex and superior pseudo randomness. It is extremely sensitive to the initial conditions and control parameters, thus any tiny initial deviation will be highly amplified, conforming to diffusion rule. In addition, it can be determined by nonlinear system equation, system parameters and initial conditions. Because of the characteristics of chaotic system with uncertainty, randomness, ergodicity and highly sensitivity of initial values, we could design a series of excellent algorithms with larger key space and stronger randomness of keystream. Therefore, a design and implementation of digital image encryption algorithm based on chaotic systems is put forward, mainly including two parts:(1) We put forward a new chaos-based image encryption algorithm with dynamic key selection mechanism. This method adopts the hyper chaotic system to generate the pseudo-random sequence, and permutates and diffuses the image with the keys which are selected dynamically from the pseudo-random sequence we obtained by employing the DKSGSM(Dynamic Keystream Sequence Group Selection Mechanism) and DKSM(Dynamic Keystream Selection Mechanism). Then, we encrypt the image from the reverse direction after we complete the forward encryption in order to spread the influence to the whole image once a tiny change in plain image. At last, this part carries out an experimental simulation and a safety analysis.(2) We put forward an image encryption algorithm based on memristive chaotic system, cellular automata and DNA technology. In this method, we calculate the initial value of the chaotic system by the 256 bit keys which are generated by the SHA-256 function and plain image. Then we transform the eight bit planes of the plain image into DNA matrix dynamically, at the same time, we depart the DNA matrix into groups and conduct XOR operations with the cellular matrix which also has been transformed into DNA matrix dynamically. Then we obtain the encryption image by converting the DNA matrix to decimal matrix. Finally, an experimental simulation and a safety analysis are conducted.