Image encryption scheme with bit-level scrambling and multiplication diffusion

As the most effective method of multimedia security protection, image encryption is widely used in data hiding, security authentication and content protection. However, the security and efficiency are still the key issues of image encryption algorithm. In this paper, a grayscale image encryption scheme based on the architecture of bit-level scrambling and multiplication diffusion is proposed. Firstly, the input image is decomposed into eight bit planes and randomly divided into three parts. Secondly, the scrambling process of each part is respectively realized by using binary tree, flip scrambling and improved circle index scrambling. Finally, the diffusing operation of the scrambled components is executed by improving the GF (257) domain multiplication. The remarkable advantage of the scrambling operation is that it not only effectively permutes the pixels, but also permutes the bits in each pixel, and consequently it sufficiently destroys the correlation of adjacent pixels. And the parallel processing of different scrambling operations will increase the confusion effect and real-time performance. Moreover, the key stream for scrambling and diffusion operations is designed and selected strictly dependent on the plain-image. Therefore, our encryption scheme significantly improves the security by disturbing known-plaintext and chosen-plaintext attacks. Simulation experiments and security analyses further verify that the proposed algorithm is secure and effective to withstand various attacks.