Image Cryptography Based On Chaotic System And Lifting Algorithm

With the rapid development of high-speed communication technology and computer technology,people pay more and more attention to image information security.Many cryptographers are committed to the research work of image information encryption,in order to achieve the purpose of image information security communication.With the improvement of computer’s computing power,the traditional text encryption technology is not suitable for the existing image encryption requirements.It is found that the extreme sensitivity,pseudo randomness and unpredictability of chaotic system to its initial conditions are similar to those of image encryption system.And can be applied to image encryption system.Combining chaos system and lifting structure technology,two kinds of image encryption algorithms are designed,and the simulation analysis and security performance evaluation of the image encryption system are carried out,which proves that the proposed image encryption system has excellent security performance and can be used in the application of network communication and wireless communication.After reviewing the research background and significance of image encryption algorithm,this dissertation focuses on the image encryption system architecture and the research status of image encryption algorithm combining chaotic system with DNA coding or quantum computing,and analyzes the current research status of image encryption algorithm based on natural fusion chaos theory and lifting structure.Based on the research of the existing chaotic image encryption algorithm,a chaotic image encryption algorithm with plain-image related is designed.Using a key to generate four pseudo-random matrices by means of piecewise linear mapping,the plain image is processed by plain-image independent diffusion and plain-image related scrambling,and then the ciphered image is obtained by a reverse diffusion operation.Simulation results show that the proposed algorithm has the characteristics of fast encryption speed and high security performance.On the basis of the above research,inspired by integer wavelet lifting algorithm,the chaotic image encryption algorithm based on lifting structure is further studied.With the help of lifting algorithm,the plain image is decomposed into even sequence and odd sequence,and then the diffusion algorithm is applied to the two sequences through prediction and update algorithm,and the disturbed two ciphered sequences are obtained by repeating the process many times.The two sequences are combined and the ciphered image is obtained by matrix.A large number of simulation experiments show that the proposed algorithm has scalability and excellent security performance.