Chaotic image encryption using circular shift and modular arithmetic

In this paper, an image encryption algorithm using a proposed cosine chaotic map is designed. The proposed image encryption algorithm uses two levels of permutation and three levels of diffusion. The first level of permutation is done using chaotic index sequence. Second level of permutation is carried out using transformation matrix. Transformation matrix is generated using the index sequence generated by the proposed map. Modular arithmetic is used for the first level diffusion. Second level diffusion are carried out using chaotic controlled circular shift. Row and column diffusion using XOR operation is done as the third level of diffusion. The performance metrices local entropy, global entropy, chi-square, correlation coefficient, NPCR, UACI, PSNR, MSE, key space are computed for different test images. Wide chaotic region of the proposed map and large key space are verified through simulations.