New Low-Area Designs for the AES Forward, Inverse and Combined S-Boxes

The implementation of AES S-boxes is one of the most extensively studied areas of cryptography. In this paper, we propose three new hardware designs for the AES S-box that can serve in the forward, inverse and combined data paths. Each of these designs represents the smallest AES S-box ever proposed in its respective category. We achieve this goal by using new tower field representation over normal bases and optimizing each and every block inside the three proposed architectures. Our complexity analysis and ASIC synthesis results in the CMOS STM 65 nm, as well as the NanGate 15 nm technologies, show that our designs outperform their counterparts in terms of area and power.