Highly dispersive substitution box (S‐box) design using chaos.

Highly dispersive S‐boxes are desirable in cryptosystems as nonlinear confusion sub‐layers for resisting modern attacks. For a near optimal cryptosystem resistant to modern cryptanalysis, a highly nonlinear and low differential probability (DP) value is required. We propose a method based on a piecewise linear chaotic map (PWLCM) with optimization conditions. Thus, the linear propagation of information in a cryptosystem appearing as a high DP during differential cryptanalysis of an S‐box is minimized. While mapping from the chaotic trajectory to integer domain, a randomness test is performed that justifies the nonlinear behavior of the highly dispersive and nonlinear chaotic S‐box. The proposed scheme is vetted using well‐established cryptographic performance criteria. The proposed S‐box meets the cryptographic performance criteria and further minimizes the differential propagation justified by the low DP value. The suitability of the proposed S‐box is also tested using an image encryption algorithm. Results show that the proposed S‐box as a confusion component entails a high level of security and improves resistance against all known attacks. [ABSTRACT FROM AUTHOR]