The fast image encryption algorithm based on lifting scheme and chaos Abstract   Image encryption technology is one of the most important means of image information security. Most image encryption algorithms are based on a permutationxe2x88x92diffusion 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 lowfrequency approximate components and highfrequency detailed components. Pseudorandom 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 permutationxe2x88x92diffusion structure, the proposed image cryptography requires fewer pseudorandom 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.

Fast and Efficient Image Encryption Algorithm Based on Modular Addition and SPD Bitlevel and pixellevel methods are two classifications for image encryption, which describe the smallest processing elements manipulated in diffusion and permutation respectively. Most pixellevel permutation methods merely alter the positions of pixels, resulting in similar histograms for the original and permuted images. Bitlevel permutation methods, however, have the ability to change the histogram of the image, but are usually not preferred due to their timeconsuming nature, which is owed to bitlevel computation, unlike that of other permutation techniques. In this paper, we introduce a new image encryption algorithm which uses binary bitplane scrambling and an SPD diffusion technique for the bitplanes of a plain image, based on a card game trick. Integer values of the hexadecimal key SHA512 are also used, along with the adaptive blockbased modular addition of pixels to encrypt the images. To prove the firstrate encryption performance of our proposed algorithm, security analyses are provided in this paper. Simulations and other results confirmed the robustness of the proposed image encryption algorithm against many wellknown attacks; in particular, bruteforce attacks, knownchosen plain text attacks, occlusion attacks, differential attacks, and gray value difference attacks, among others.