Boolean Exponent Splitting

A typical countermeasure against side-channel attacks consists of masking intermediate values with a random number. In symmetric cryptographic algorithms, Boolean shares of the secret are typically used, whereas in asymmetric algorithms the secret exponent is typically masked using algebraic properties. This paper presents a new exponent splitting technique with minimal impact on performance based on Boolean shares, typically requiring only an extra register and a few register copies per bit. We perform a security evaluation of our algorithms using a mutual information framework and provide proofs that they are secure against first-order side-channel attacks. The side-channel resistance of the proposed algorithms are also practically verified with test vector leakage assessment performed on Xilinx's Zynq zc702 evaluation board.