Modified AES Algorithm Using Multiple S-Boxes

This paper proposes for a modified version of the AES algorithm using multiple Sboxes. While many studies have been conducted specifically on modifying the Sbox, these studies were made to replace the Rijndael Sboxes in the AES cipher. We propose to implement two substitution boxes, where the first Sbox is the Rijndael Sbox and will be used as is. The second Sbox was constructed through an XOR operation and affine transformation and will replace the MixColumns operation within the internal rounds in the cipher. Based on simulation testing conducted, it was found out that the modified AES algorithm using multiple SBoxes has better speed performance compared to the original cipher. However, when tested using the avalanche effect, the changes in the output bits were below the minimum expected rate.