A Plain- Image Dependent Image Encryption Scheme Using Half-Pixel-Level Interchange Permutation Operation

In this paper, a chaos-based image encryption scheme with half-pixel-level interchange permutation strategy and plain-image dependence is proposed. The proposed image encryption scheme consists of a confusion process and a diffusion process. In the confusion process, a pixel-swapping operation between higher bit planes and lower bit planes is employed to replace the traditional confusion operation. The halfpixel-level interchange permutation strategy between the higher 4-bit plane part and the lower 4-bit plane part not only improves the conventional permutation efficiency within the plain-image, but also changes all the pixel gray values. The system parameters of generalized Arnold map applied for the permutation operation relies on the plain-image content and consequently can resist chosen-plaintext and knownplaintext attacks effectively. To enhance the security of the proposed image encryption, one multimodal skew tent map is utilized to generate pseudo-random gray value sequence for diffusion operation. Simulations have been carried out thoroughly with comparisons with some other existing image encryption schemes. The experimental results demonstrate that the proposed image encryption scheme is highly secure thanks to its large key space and efficient permutation-diffusion operations.