Image Encryption Algorithm And Implementation Based On Variable Parameter Chaos And Ciphertext Domain Extension

With the development of computer network technology and communication technology,the exponential growth of multimedia data represented by images and videos has exploded.How to ensure the security of multimedia data has become an important research topic.Among them,image encryption,as a key multimedia information security technology,can prevent attackers from obtaining image content.By studying a large amount of literature,two types of defects that can be found in most algorithms are summarized.The first type of defects are general algorithm types.They are:the singleness of chaos makes it difficult to be cracked;the limitation of the limited numerical precision of computers leads to chaotic sequences The chaos performance is degraded;the encryption algorithm cannot resist noise,shear and compression attacks;the encryption algorithm is not sensitive to plaintext;the encryption algorithm cannot resist the choice of plaintext attacks.The second type of defects are object defects for color images.Compared to grayscale images,color images have stronger expression and larger dimensional space.A true-color image can be decomposed into R,G,and B primary color components.After the decomposition,the encryption object space is increased.Researchers can use imagination in terms of key stream complexity and algorithm complexity.However,the three primary color components of R,G,and B have a high correlation with the original image,so that as long as any one of the components is cracked,it is equivalent to cracking the plaintext.In this paper,with the main idea of??ciphertext domain expansion and the main goal of solving the above problems,an image encryption algorithm based on variable parameter chaos and ciphertext domain expansion is proposed.In order to solve the defects of general algorithms,an ectopic XOR image encryption algorithm based on variable parameter chaos is designed.In this algorithm,a new three-dimensional variable parameter hyperchaotic system is constructed in order to solve the problem of unity of chaos.The system consists of Generalized Henon mapping control.For the encryption algorithm can not resist the attack of noise,shear and compression,the pixel position scrambling algorithm is added to the encryption algorithm.For the problem that the encryption algorithm is not sensitive to plaintext,the plaintext association is added to the algorithm.Factors make the initial conditions for generating chaotic sequences related to the plaintext image.In view of the shortcoming that the algorithm cannot resist the selection of plaintext attacks,in the encryption algorithm,the plaintext is divided into blocks,and ciphertext feedback is used to sequentially encrypt blocks.And in the diffusion part,a custom block heterotopic XOR numerical diffusion algorithm is designed,and the idea is to expand the ciphertext domain to convert the two-dimensional grayscale image into a three-dimensional ciphertext image.In order to solve the object class defects of color images,a complex chaotic color image encryption algorithm based on inter-layer associations is designed.Based on the idea of inter-layer associations,a new idea of scrambling and diffusion is injected into the algorithm.First,construct a new four-dimensional variable parameter chaotic system.Second,in the scrambling part,design a spatial parallel scrambling algorithm based on inter-layer correlations.In the diffusion part,design a spatial ordered diffusion algorithm based on inter-layer correlations.The idea of domain expansion makes a plaintext image of size N?N?3 into a ciphertext image ofM₁?M₂?3.The layer-to-layer association mode makes it impossible for an attacker to crack any one of the components in a single layer,which makes the cracking difficult.