Using Normal Bases for Compact Hardware Implementations of the AES S-Box

Abstract. The substitution box (S-box) of the Advanced Encryption Standard (AES) is based on the multiplicative inversion s(x) = x-1 in GF(256) and followed by an affine transformation in GF(2). The S-box is the most expansive building block of any hardware implementation of the AES, and the multiplicative inversion is the most costly step of the S-box transformation. There exist many publications about hardware implementations of the S-box and the smallest known implementations are based on normal bases. In this paper, we introduce a new method to implement the multiplicative inversion over GF(256) based on normal bases that have not been considered before in the context of AES implementations.

• Type: Journal
• Year: 2008
• Where: SCN
• Authors: Svetla Nikova, Vincent Rijmen, Martin Schläffer
• Keywords: Advanced Encryption Standard, Communications, Hardware Implementations, Multiplicative Inversion, SCN 2008