Research Of Image Encryption Algorithm Based On Chaos Theory

In recent years,with the development of Internet technology and digital image technology,digital image security has quickly become a research hotspot.However,digital images have the characteristics of large amount of information,high correlation and strong redundancy.Some traditional encryption algorithms cannot encrypt them well.Therefore,based on the traditional image encryption algorithm,the following two improved encryption algorithms are proposed:1)Based on the traditional Joseph traversal mapping and Logistic chaotic system,an improved image encryption algorithm is designed.The algorithm adds the random number position and the random number interval of the Joseph traversal map to the traditional Joseph traversal to increase the permutation variable of the Joseph traversal map.In order to correlate the intermediate control parameters generated in the encryption process with the image to be encrypted,a three-dimensional Logistic chaotic map is added,and the initial parameters of the three-dimensional Logistic chaotic map are generated by combining the MD5 values of the image to be encrypted.In view of the low coupling degree between the permutation operation and the diffusion operation in the current algorithm,the improved Joseph traversal mapping is used to replace the bit pixels in different directions,and diffusing with its neighboring pixel values,it can not only change the position of the pixel value of the bit to be encrypted,but also can change the size of the pixel value,so that the replacement operation and the diffusion operation are well coupled.2)Based on the improved Joseph traversal mapping,an image encryption algorithm based on double chaotic mapping and projection segmentation is proposed.The algorithm uses the PWLCM chaotic map to generate an intermediate cryptographic parameter of the improved Joseph traversal map to scramble the image.Aiming at the low security of the traditional block cipher diffusion algorithm,a random projection diffusion algorithm is proposed to randomly divide the image into multiple overlapping blocks.For each block,divide it into a set of projection lines.The Lorenz chaotic system is used to generate an intermediate key sequence data pool,and the data is encrypted by performing an exclusive or operation with the selected sequence in the intermediate key data pool by using a random projection sequence.Through the histogram,key space,anti-differential attack analysis,correlation analysis and information entropy analysis,the security analysis of the improved algorithm shows that the algorithm designed in this dissertation couples the bit-pixel replacement and diffusion together,has better encryption effect,and can resist the differential attack analysis.It has a good development prospect in image encryption applications.Figure[14]table[8]references[65]...