An Efficient Diffusion Approach for Chaos-based Image Encryption
Kwok Wo WONG, Bernie Sin-Hung KWOK
A typical architecture of existing chaos-based image cryptosystems is composed of alternative permutation and diffusion stages. A multi-dimensional chaotic map is usually employed for image pixel permutation in the spatial domain while a one-dimensional (1D) chaotic map is used for diffusion purpose. As the latter usually involves real-valued arithmetic operations, the overall encryption speed is limited by the diffusion stage. In this paper, we propose a more efficient diffusion mechanism using simple table lookup and swapping techniques as a light-weight replacement of the 1D chaotic map. Simulation results show that at a similar security level, the proposed cryptosystem needs only one-third the encryption time of an existing cryptosystem. The effective acceleration of chaos-based image cryptosystems is thus achieved.