Power Profile Equalizer: A Lightweight Countermeasure against Side-Channel Attack

Abstract

Power attack is an important side-channel attack (SCA) method based on the correlation between measured power profile and internal switching activities. Various techniques have been proposed to prevent power attack. It has been noted that the on-chip power grid (PG) has a vital effect on the effectiveness of power attack by inducing a noise in the power profile. However, there is a lack of study on this intrinsic effect of PG. In this paper, we explore the methods of exploiting the PG-induced noise to counter with power attack. We note that the PG-induced noise strongly depends on the PG impedance and it can be regulated by adjusting the PG capacitor to control the power profile to fixed values, which contributes to reducing the power leakage. Further, we propose a novel adjustment technique for PG capacitor, i.e. power profile equalizer (PPE), as a lightweight (low-overhead) countermeasure against power attack. PPE exploits the regulated noise to equalize the power profile without violating the layout and supply noise constraints. To reduce the overheads, random walk is adopted to utilize the utmost on-chip resources. Moreover, PPE is implemented by optimizing PG which is an essential IC component rather than producing new circuits. As a result, PPE incurs low overheads. Experimental results show that PPE is able to improve the measurements to disclose (MTD) by 1800x while the area and power increase respectively by 0.12% and 0.91%.