Unified Image Encryption Algorithm Based On Chaotic System And Wavelet Transform

In the context of the rapid development of computer network technology,information security is becoming increasingly serious,and multimedia data such as text,images and videos are easy to be eavesdropped or maliciously damaged when they are transmitted in open networks.Among them,for digital images as a commonly used information carrier,effective encryption technology is essential to ensure its information security.The latest research on image information encryption is to combine chaotic systems traditional image encryption framework,and to achieve the confusion and diffusion of image information by a large number of ciphers generated by chaotic key generator.In order to further break through the traditional dislocation and diffusion encryption framework,this dissertation investigates the image encryption algorithm based on chaotic system and lifting structure to obtain a novel image encryption system with fast encryption rate and strong encryption security.Based on the study of lifting transformation theory,a new image encryption algorithm based on lifting transformation is proposed,which generates pseudo-random sequences using chaotic systems with the help of secret keys,where the keys are used as the initial values of chaotic systems,and the state sequences generated by iterative chaotic systems are transformed by S-box and cyclic displacement techniques to obtain equivalent keys.The lifting transform-based encryption framework splits the plaintext image oddly and evenly,and the two sequences are predicted and updated with each other,and the information is diffused with the help of the equivalence keys during the transformation process.After the process of splitting,predicting and updating the image data twice,and the scrambled two sequences are transformed to a matrix of the same size as the original image,which is the ciphered image.It is confirmed by a large number of simulation experiments that the proposed algorithm generates the ciphered images with good statistical properties,and all sensitivity test values of the system are close to their theoretical values,and the encryption and decryption speed is fast.Thus,the proposed cryptograph is an excellent image encryption scheme.Based on the above-mentioned study of lifting-transform image encryption algorithm,the unified image cipher algorithm based on chaotic system and lifting-transform is proposed by integrating the unified encryption theory.Also,considering the small key space of the low-dimensional chaotic system,the uneven distribution of the generated sequences,and the occurrence of breakpoints in the chaotic interval,etc,thus,in this unified image encryption algorithm,the chaotic sequences used by the algorithm are generated using the composite operation of two low-dimensional chaotic systems.For this algorithm,its biggest feature is that the encryption process is exactly the same as the decryption process.If the secret key and the original image are input,the output result is ciphed text image after system processing;if the secret key and the ciphered image are input,the output result is the original image after system processing.The proposed image cryptographic system can save half of the hardware resources and software resources.Simulation experiments and security performance analysis confirm that the proposed unified cryptosystem has the advantages of fast processing speed,large key space and high system sensitivity,and can be used as an alternative image encryption scheme for network image information security.