Ultra-lightweight 8-bit Multiplicative Inverse Based S-box Using LFSR

Most of the lightweight block ciphers are nibble-oriented as the implementation of a 4-bit S-box is much more compact than an 8-bit S-box. This paper proposes a novel implementation of multiplicative inverse for 8-bit S-boxes using LFSR requiring only 138 gate-equivalent. It can be shown that if such S-boxes are adopted for the AES it takes less than 50 gate-equivalent per S-box in parallel implementation. Canright’s [1] implementation of the AES S-box is five times more expensive compared to this method for AES-like S-boxes. With this powerful scheme, a lightweight block cipher can be designed using an 8-bit S-box.