A Fast Chaos-Based Symmetric Image Cipher with a Novel Bit-Level Permutation Strategy

Abstract

This paper presents a fast chaos-based confusion-diffusion type image cipher which introduces a diffusion mechanism in the confusion stage through a novel bit-level permutation. As the pixel value mixing effect is contributed by both stages, the workload of the time-consuming diffusion stage is reduced, and hence the performance of the cryptosystem is improved. Compared with those recently proposed bit-level permutation algorithms, the diffusion effect of the proposed scheme is significantly enhanced as the bits are shuffled among different bitplanes rather than within the same bitplane. Moreover, the pseudorandom locations for bits permutation are produced in a parallel manner, which further increase the performance. Lorenz system is employed as generation of keystream for diffusion. Extensive cryptanalysis has been performed on the proposed scheme, and the results demonstrate that the proposed scheme has a satisfactory security level with a low computational complexity, which renders it a good candidate for real-time secure image transmission applications.