Digital Image Encryption And Compression Algorithm Based On Multiple Chaotic Systems

As an important information carrier,digital image is more and more widely used in various fields with the rapid development of information technology.However,because the multimedia data is transmitted on the public channel,it is vulnerable to malicious damage or tampering by attackers,and changes the original information of the image.Therefore,it is necessary to complete the image encryption before image transmission.Moreover,with the continuous growth of multimedia data,images need to occupy a larger transmission bandwidth in the transmission process.The transmission efficiency of image is greatly reduced due to the limited transmission bandwidth.In order to reduce the image transmission time and improve the transmission efficiency,the most effective way is to compress the image.Compression is to remove redundant information by means of the correlation of adjacent pixels of image,while encryption is to eliminate redundant information of adjacent pixels to achieve the purpose of confusion,there is a contradiction between the two.Therefore,how to effectively combine compression and encryption to achieve a safe and efficient image encryption and compression algorithm is one of the current research hotspots.As a kind of nonlinear dynamic system,chaotic system has the characteristics of initial value sensitivity,non periodicity and uncertainty,which makes it very suitable for generating the key stream of encryption system.The structure of the typical one-dimensional chaotic map attractor is relatively simple,it is vulnerable to the attack of phase space reconstruction.In order to generate a more secure key stream,It is necessary to construct a more complex chaotic system.In this paper,several secure chaotic systems are constructed to generate secure key stream.Firstly,based on the coupled map lattice spatiotemporal chaotic system and 3D Arnold map,a more secure spatiotemporal chaotic system with non adjacent coupled map is constructed.Secondly,a compound chaotic map model,namely two-dimensional Logical coupling Sine chaotic map,is constructed by Logistic map and Sine map.Similarly,a two-dimensional Sine coupling cubic is constructed by Logistic map and Cubic map.The new chaotic model has larger key space,better randomness and higher security.Based on multiple chaotic systems,we first study the image encryption algorithms in this paper,and then designs a variety of image encryption and compression algorithms.The proposed algorithms are as follows:(1)Gray image encryption algorithm is proposed based on the coupled map lattice space-time chaotic system.The encryption algorithm adopts the scrambling and diffusion encryption structure,and can encrypt multiple gray images at the same time.Experiments show that the encryption algorithm has good encryption performance.(2)A color image encryption algorithm based on non adjacent coupled map lattice space-time system is proposed,improves the structure of adjacent coupled map lattice space-time chaotic system and encryption algorithm in the previous chapter,and proposes a novel encryption structure,namely scrambling-diffusion-substitution.Experiments show that the encryption algorithm has low complexity and can resist various typical attacks.(3)Based on the proposed new hyperchaotic system,compressed sensing technology and block compressed sensing technology,two lossy image encryption and compression algorithms are studied.The images of the two algorithms are scrambled and diffused after compression preprocessing and compression quantization,respectively,to achieve the safe and effective image transmission.(4)Based on some typical chaotic systems,a lossy image encryption and compression algorithm based on Lifting Wavelet Transform(LWT),Set Partitioning in Hierarchical Trees(SPIHT)and Cellular Automata(CA)is proposed.Compared with compressed sensing technology,SPIHT combined with LWT realizes lossless image coding and compression.At the same time,encryption is embedded in the compression process to realize the safe and effective image transmission.