Research And Design Of Image Encryption Algorithm Based On Hyperchaotic System

At present,with the rapid development of communication network technology,a large amount of data information is widely spread in e-commerce,medical care,e-government and other aspects.Therefore,the problem of information communication security becomes m ore and more prominent,and how to ensure the safe transmission of information on network channels becomes more and more important.Among the numerous information,image information is characterized by vividness,intuition and large amount of information,so image is more widely used than text,voice and other information.However,due to the characteristics of high redundancy,strong correlation and two-dimensional distribution of images,common encryption algorithms such as DES,AES and IDEA applied to im age encryption cannot guarantee the security of image information,and have low encryption speed.With the development of chaotic theory,researchers have found that chaotic systems have some characteristics such as unpredictability,high sensitivity to pa rameters and initial values,pseudo-randomness and ergodicity,which are very suitable for image encryption.Moreover,the designed image encryption algorithms based on chaotic systems have higher security and faster encryption speed.Therefore,more and m ore researchers are devoting themselves to the research of image encryption scheme based on chaotic system design.This paper focuses on the design of high security image encryption schemes based on hyperchaos systems.Firstly,the background and significa nce of research are summarized,and the research status of chaotic image encryption schemes at home and abroad is introduced.Then,the chaotic theory,cryptography and the basic process of chaotic image encryption and security analysis standards are descr ibed in detail.Finally,two image encryption schemes are designed based on hyperchaos systems.The details are as follows.(1)A hyper-chaotic image encryption algorithm based on breadth-first traversal and dynamic diffusion is proposed in this paper,which can solve the disadvantages of some scrambling algorithms that can not completely disrupt the image adjacent pixel correlation and the problem that when the scrambled key stream and the diffusion key stream are independent of each other in many schemes based on the permutation-diffusion architecture,the scrambled key sequence and the diffusion key sequence can be broken separately.The proposed scheme is introduced in details: Firstly,the plain image is traversed by breadth-first search in the scrambling process,which can completely scramble the positions of pixels.Secondly,the diffusion key stream is rearranged by breadth-first search under the control of scrambled key stream,so as to improve the security of the algorithm.Finally,a dynamic diffusion method is designed to encrypt the image pixels.(2)An image segmentation encryption algorithm based on hyper-chaotic system is proposed in this paper,which can solve the shortcoming that differential attacks can not be resisted in many algorithms in which the plaintext and ciphertext do not participate in the process of generating key sequences.The proposed scheme is introduced in details: Firstly,the scrambled image is divided into three sequences under the control of chaotic sequences.Then,the three sequences are respectively encrypted,and when each sequence is encrypted,the other two sequences participate in the generation of chaotic pseudo-random sequences in order to improve the algorithm's ability to resist differential attacks.Finally,t he final ciphertext sequence is obtained by splicing the three encrypted sequences.Finally,this paper analyzes the security of these two chaotic image encryption algorithms from key space,statistical analysis,difference analysis,key sensitivity and ot her aspects.The whole experiments are simulated in Matlab.The results show that these two algorithms have higher security and faster encryption speed than other algorithms.