Chaos-Based Image Encryption Using Sum Operation Modulo 4 and 256
Mohamad Javad Rostami, Saeı̈d Saryazdi, Hossein Nezamabadi–pour, Abbas Shahba · IETE Journal of Research · 2015
Today the security of images has become increasingly important in the realm of information technology (IT). A secure image encryptor must have a pseudo-noise output for each input and resist various attacks. In this paper, an algorithm was proposed in terms of encrypting colour images using chaotic logistic map and sum operation modulo 4 and 256. Generally speaking, in this algorithm the sum operation is first conducted on the pixels of the image employing a two-step modulo 256; the resulting image is then divided into four sub-matrices each of which is converted into modulo 4. The sum process modulo 4 is then conducted on these four sub-matrices and four other random sub-matrices. The pixels are finally permuted using the chaotic map. Our simulation results and the comparison with similar works showed that this algorithm has appropriate resistance against static and differential attacks as it has the three important characteristics of permutation, substitution, and diffusion. Its pseudo-noise output is largely dependent upon the key, and it also provides a safe key space to prevent brute force attack.