An efficient image encryption algorithm based on blocks permutation and Rubik´s cube principle for iris images

This paper proposes an efficient image cryptosystem based on permutation and diffusion operations in order to enhance the protection of iris-based systems against replay attacks. These attacks have been identified and located in different points by Ratha et al. [1]. First, the original image is partitioned into blocks, which are then permuted using a permutation key. After that, the Rubik´s cube principle is applied to each block in order to obtain a scrambled image. Finally, the pixels values of rows and columns of the scrambled image are changed using XOR operator to generate the encrypted image. Experimental tests and security analysis have been carried out on iris images, chosen from CASIA database [2]. The obtained results clearly show the robustness of the proposed image cryptosystem against common attacks, namely exhaustive, differential and statistical attacks and also reveal the high security level achieved by the proposed algorithm.