Research On Digital Image Encryption Based On Chaos Theory And Bit-level Adaptive

With the vigorous development of network informatization,the dissemination of multimedia information exists in all aspects of personal life and national security.Encryption systems are an important means of protecting network information security,and digital images account for a large proportion in the Internet.If the image The information is not well protected and important information is stolen,which will cause great losses.As an important method of hiding information,image encryption plays a vital role in the protection of information security.In view of the development status of image encryption research,three new image encryption algorithms are designed in this paper,which enriches the algorithm and technical innovation of image encryption theory,and has certain theoretical significance and practical application value.From the perspective of algorithm research and practicality,the main research work is as follows:(1)An image encryption algorithm for dual scrambling and C-R chaotic systemIn order to solve the problems of large amount of image encrypted data,slow transmission rate,security and complexity of encryption algorithm,this algorithm designed an image encryption algorithm that can achieve global scrambling and diffusion.First,the iteration value of the Sine model is used as the system parameter of Chebyshev mapping,and then a pseudo-random sequence is generated and the index position is sorted.The index sequence position number is transformed with the ascending sequence row,and then with the descending sequence column transformation,Arnold scrambling and merging each pixel matrix to form a completely scrambled encrypted image;Then,a three-dimensional CNN-Rossler(C-R)chaotic map is proposed,and its chaosity is verified according to the Lyapunov index.Perform a diffusion operation on the pixel values of the scrambled image;Finally,perform bit-wise xor on the scrambled image and the pixel scrambled image to obtain the ciphertext image.Simulation experiment results show that the algorithm has a large key space,can resist brute force and brute force attacks,and has strong resistance to attack and security.(2)Propose color bit-level image encryption algorithm based on L-K dual chaotic systemAiming at the problems of limited accuracy and low security of traditional encryption algorithms,a new image encryption algorithm is proposed.First,the plain text image isdivided into three layers: R,G,and B.Taking the R layer as an example,the image bit plane is decomposed into 8 layers.The chaotic sequence generated by the Liu chaotic system acts on the lower five bits to scramble the index position.Arnold scrambling is performed on the upper three bits;then,the encryption algorithm of the lower five bits to fully obfuscate and diffuse the upper three bits is designed,and a scrambling-diffusion is completed.The G layer and the B layer use the same method;Then,at the pixel level,the Kawakami hyperchaos combines ciphertext image information for fractal diffusion,combined with pixel-level encryption for Hilbert scrambling,completes the second scrambling-diffusion operation,and finally obtains the ciphertext image.Simulation experiments show that the algorithm is very safe and can be applied to the encryption method of information dissemination.(3)A dynamic bit-level image encryption algorithm based on compressed sensing and hyperchaos is proposedAiming at the problems of low real-time transmission and large information channel occupied by most image encryption algorithms,a compression sensing combined with Rabinovich hyperchaos is proposed.First,the plaintext image is transformed by DWT to obtain a sparse basis matrix.Encryption and compression are performed simultaneously.The Rabinovich hyperchaotic sequence is improved to obtain a highly sensitive chaotic sequence.Then,a double-reset chaos mechanism related to the plaintext is designed to align the four planes after the plane decomposition are designed with an adaptive scrambling method to complete one scrambling,and then perform Zig-Zag global scrambling.Then,an encryption engine function is introduced to perform an annular diffusion function on the image,and forward diffusion and reverse diffusion are respectively performed;Finally,the random gaussian measurement matrix is used to perform compressed sensing sampling on the encrypted image to form the final ciphertext image.Simulation experiments show that the algorithm has large key space,strong sensitivity,can resist exhaustive attacks,has high real-time performance and security,and is suitable for propagation in network security.