title: A highly nonlinear S-box based on a fractional linear transformation.
abstract: We study the structure of an S-box based on a fractional linear transformation applied on the Galois field [Formula: see text]. The algorithm followed is very simple and yields an S-box with a very high ability to create confusion in the data. The cryptographic strength of the new S-box is critically analyzed by studying the properties of S-box such as nonlinearity, strict avalanche, bit independence, linear approximation probability and differential approximation probability. We also apply majority logic criterion to determine the effectiveness of our proposed S-box in image encryption applications.
authors.affiliation: Department of Mathematics, COMSATS Institute of Information Technology, Wah Cantt, Pakistan.
authors.forename: Shabieh
authors.initials: S
authors.lastname: Farwa
authors.affiliation: Department of Mathematics, Quaid-i-Azam University, Islamabad, Pakistan.
authors.forename: Tariq
authors.initials: T
authors.lastname: Shah
authors.affiliation: Department of Mathematics, COMSATS Institute of Information Technology, Wah Cantt, Pakistan.
authors.forename: Lubna
authors.initials: L
authors.lastname: Idrees
keywords: Fractional linear transformation; Galois field; Majority logic criterion; S-box