A 7-Gbps SCA-Resistant Multiplicative-Masked AES Engine in Intel 4 CMOS

A multiplicative masked advanced encryption standard (AES)-128/-256 engine with measured side-channel resistance to correlation power and electromagnetic (EM) attacks in Intel 4 CMOS process is presented. While conventional additive masking offers significant improvements in minimum-time-to-disclosure (MTD) for the extracted key bytes, mask compensations in non-linear Sboxes incur >100% area overheads. Multiplicative masking provides a simpler computation of non-linear inverse operation by converting the inputs from an additive to a multiplicative domain. However, multiplicative masked AES designs suffer from zero-value attacks, where "0" valued inputs on Sbox bytes exhibit distinct power signatures compared to a random input byte. The AES engine implements dual-rail zero-value attack detection and mitigation circuits to counteract zero-valued input Sbox bytes. Low-overhead mask conversion and multiplicative Sbox datapath circuits enable 1.8\times and 50% reduction in area and performance overheads, respectively. The countermeasure enables 34000-40 000\times improvements in measured MTD against correlation power and EM attacks compared to an unprotected AES implementation while limiting the area and performance overheads to 65% and 4%, respectively.