4D chaotic system as random Substitution-Box

Substitution -boxes have a significant role in cryptographic algorithms and they are remarkably non-linear parts of block cryptography. There are large numbers of S-Boxes algorithm designs had been proposed based on chaotic theory. Due to the demand of existence of both confusion and diffusion process, which is not available in most S-Boxes algorithms, an effective way to build Substitution-Permutation boxes based on the Qi Hyperchaotic System was included in this study. The object of this proposition is to generate S-Boxes that are more robust and can be provided both diffusion and confusion properties (substitution and permutation). The substitution process in the S-Box is stochastic through changing every byte of the state by different byte from a replacement table. Analyzing and testing were conducted for the new S-Box for the following criteria: avalanche effect, strict avalanche effect (SAC), nonlinearity, key sensitivity, differential and linear cryptanalysis. The whole results proved that the proposed method is an excellent candidate for designing S-Boxes that can be widely used in block cipher. The proposed S-Boxes are applied to a new image encryption algorithm where two S-Box for each color channel are created to perform permutation and substitution operations. Also, performance tests of the encryption algorithm have been presented.