ABSTRACT

The Advanced Encryption Standard (AES) was published by National Institute of Standards and Technology (NIST) in November 2001, to replace DES (Data Encryption Standard) and Triple DES. The S-box (Substitution box) used in AES is designed to be resistant to known cryptanalytic attacks [1][2]. The property of the S-box is that the output cannot be described as a simple mathematical function of the input. The S-box is designed to provide good avalanche effect. The Avalanche Criteria of S-box depends on the generator matrix A used in affine transformation to construct the S-box. This paper investigates the construction of Sboxes by affine transformation which satisfy maximum Avalanche Criteria.