Design And Analysis Of Digital Image Encryption Algorithm Based On Improved Chaotic System

With the advent of the era of digital intelligence,data is growing exponentially and becoming a new production factor.As one of the important information carriers,image data is used more and more widely and deeply in various fields of national economy,social production and people’s life,and at the same time,the security problem of digital images is becoming more and more prominent,and images containing private and confidential information are exposed to the risk of malicious theft and attack.Therefore,it is imperative to protect image information effectively,and image encryption technology has become a hot research topic in the academia and a focus of attention in the industry.Chaotic image encryption is based on the unpredictability,pseudo-randomness and initial value sensitivity of chaos,and the image encryption is realized by diffusion and dislocation algorithm,which has good security performance.However,the performance of chaotic image encryption is expected to be further improved in terms of chaotic system(mapping),improvement and construction of encryption algorithms.Based on this,this paper constructs new chaotic and hyperchaotic systems by coupling and improving existing chaotic systems(mappings),improves and designs new encryption algorithms,and verifies the effectiveness of the algorithms through security performance analysis experiments.The main work of the paper includes the following two major aspects:(1)A one-dimensional associative chaotic system and bit-plane dislocation based image encryption algorithm is proposed.Based on the Tent chaos mapping,a onedimensional associative chaos system(mapping)is constructed by associating Sine and Cubic chaos mappings,which has a larger chaos parameter space and better random performance than the Tent mapping.In the encryption,the plaintext image is firstly converted into a binary bit value matrix,and then the bit matrix is disordered by ranks and ranks based on the chaotic sequence generated by the associative chaos system,and then disordered by bits in blocks based on the chaotic sequence generated by the Henon chaos system,and then the chaotic sequence obtained from the associative chaos system is iterated to perform a grayscale diffusion operation on the first encrypted image to obtain the final ciphertext image.Simulation experiments and performance analysis show that this algorithm effectively solves the problem of low entropy value of ciphertext image information and has good security.(2)An image encryption algorithm based on an improved new four-dimensional chaotic system and DNA coding is proposed.Based on a four-dimensional chaotic system existing in the literature,a new four-dimensional hyperchaotic system is obtained by improving it,and the initial values of the system are generated based on SHA-256,Zig Zag transform and the input key,and four pseudo-random chaotic sequences are iteratively generated,and the image after the dislocation based on Zig Zag transform and the two-dimensional matrix based on Chebyshev chaotic sequence is implemented with DNA The ciphertext image is obtained after disruption and diffusion by block encoding,operation and decoding.Simulation experiments and security performance analysis show that the algorithm enhances the correlation between key and plaintext,the randomness of encryption process,and effectively improves the antiattack capability.