The Research And Design Of Image Encryption System Based On Conservative Hyperchaotic System

With the fast development of new media application technology in modern society,the network channel is full of all kinds of media information,and the digital images are widely disseminated over network channels.However,the fast and convenient network communication also has the hidden danger of information security,how to ensure that the image information is not stolen by the third party has become a concern of people.At present,due to the complex dynamic characteristics of chaos and its natural connection with cryptography,the field of chaotic image encryption has aroused the research enthusiasm of many scholars.Most encryption algorithms use dissipative chaotic systems with attractors,which are not resistant to reconstruction attacks.In contrast,conservative chaotic systems have no attractors,which are resistant to reconstruction attacks.Therefore,the image encryption system based on conservative hyperchaotic system can resist reconstruction attack,and has good randomness,good security and reliability.The main work of this paper is to propose two kinds of image encryption schemes which use conservative hyperchaotic system as pseudo-random number generator.At the beginning of the paper,the significance and background of this research are introduced,then the basic knowledge of chaos and image encryption is detailed,including the concepts of chaos,cryptography and chaotic image encryption.Then two methods and steps of combining conservative hyperchaotic system with other algorithms are given to design image encryption system,and the advantages of its performance are pointed out through simulation analysis.Specific research contents are as follows:(1)An image encryption scheme combining closed-loop diffusion between blocks and conservative hyperchaotic system is proposed.The main advantages of this scheme are the anti-reconfiguration aggressiveness of conservative hyperchaotic system and the stability of closed-loop diffusion between blocks.Firstly,the encryption keys needed for scrambling and diffusion are generated by hashing and quantizing the pixel values of the plaintext image respectively,and then the random sequences generated by the chaotic system are used for global scrambling,block label scrambling and closed-loop diffusion between blocks.In the diffusion stage,random ciphertext feedback and closed-loop feedback are introduced to make the encryption system more secure and reliable.Simulation experiments and performance analysis show that the algorithm performs well against plaintext and ciphertext attacks as well as refactoring attacks.(2)An image encryption algorithm based on multiple helical traversal and conservative hyperchaotic system is proposed.The main feature of the algorithm is that the multiple spiral traversal can make the encryption scramble more thoroughly,and the selective diffusion and random diffusion in the diffusion stage also guarantee the security of the encryption.First,the image is scrambled by using multiple spiral traversal,then the image is scrambled by using index sorting of chaotic sequence,and then selective diffusion and ciphertext feedback random diffusion are carried out.Among them,the generation of key is dependent on the plaintext image.Through some performance test and simulation,it is found that the scrambling effect of this algorithm is better than other algorithms,and it is very sensitive to the key and the plaintext image,and it can resist a wide variety of attacks.