The fast image encryption algorithm based on lifting scheme and chaos

Image encryption technology is one of the most important means of image information security. Most image encryption algorithms are based on a permutation- diffusion structure. However, some image cryptosystems based on this structure have been proved to be insecure. Thus, a new image encryption structure based on a lifting scheme is proposed in this study. In the proposed algorithm, the plain image is decomposed into low-frequency approximate components and high-frequency detailed components. Pseudo-random sequences generated by chaos are employed to sequentially disturb the two sets of components. Then a lifting scheme is used for image encryption. Compared to the currently popular permutation- diffusion structure, the proposed image cryptography requires fewer pseudo-random numbers, and it has a faster encryption speed and higher security. Simulations, performance analysis, and comparison tests show that the proposed method has the advantages of large key space, fast encryption and decryption speeds, strong system sensitivity, and excellent encryption security. The algorithm can be used in applications such as encryption of medical and cloud images. (c) 2020 Elsevier Inc. All rights reserved.