Biblio

Online template attacks (OTA), high-efficiency side-channel attacks, are initially presented to attack the elliptic curve scalar. The modular exponentiation is similarly vulnerable to OTA. The correlation between modular multiplication's intermediate products is a crucial leakage of the modular exponent. This paper proposed a practical OTA countermeasure based on randomized domain Montgomery multiplication, which combines blinding and shuffling methods to eliminate the correlation between modular multiplication's inner products without additional computation requirements. The proposed OTA countermeasure is implemented on the Sakura-G board with a suppose that the target board and template board are identical. The experiment results show that the proposed countermeasure is sufficient to protect the modular exponentiation from OTA.