An Efficient Masking Method for AES Using Tower Fields

A combination of the Boolean masking with the multiplicative masking for AES S-box is secured against side-channel attacks, particularly power analysis attacks. However, it is paid for by significantly increasing the complexity of the S-box implementation in hardware. This paper proposes a masking method based on the inversion in the tower field to cope with that problem. The experimental results show that the proposed method assures security against CPA up to 30,000 traces with the AES-TFM-2 scheme and more than 12,660 traces with the AES-TFM-1 one. There is a trade-off between the security level and the hardware implementation cost of the two proposed schemes. However, the technique reduces that cost considerably compared to existing approaches, and it is also secured against zero-value attacks.