DeMiST: Detection and Mitigation of Stealthy Analog Hardware Trojans

The global semiconductor supply chain involves design and fabrication at various locations, which leads to multiple security vulnerabilities, e.g., Hardware Trojan (HT) insertion. Although most HTs target digital circuits, HTs can be inserted in analog circuits. Therefore, several techniques have been developed for HT insertions in analog circuits. Capacitance-based Analog Hardware Trojan (AHT) is one of the stealthiest HT that can bypass most existing HT detection techniques because it uses negligible charge accumulation in the capacitor to generate stealthy triggers. To address the charge sharing and accumulation issues, in this paper, we first propose a novel way to detect such capacitance-based AHT. Secondly, we critically analyzed existing AHTs to highlight their respective limitations. By addressing these limitations, we proposed a stealthier capacitor-based AHT (fortified AHT) that can bypass our novel AHT detection technique. Finally, by critically analyzing the proposed fortified AHT and existing AHTs, we developed a robust two-phase framework (DeMiST) in which a synchronous system can mitigate the effects of capacitance-based stealthy AHTs by disabling the triggering capability of AHT. In the first phase, we demonstrate how the synchronous system can avoid the AHT during run-time by controlling the supply voltage of the intermediate combinational circuits. In the second phase, we proposed a supply voltage duty cycle-based validation technique to detect capacitance-based AHTs. Furthermore, DeMiST amplified the switching activity for charge accumulation to such a degree that it can be easily detectable using existing switching activity-based HT detection techniques. To illustrate the effectiveness, we evaluated the proposed fortified AHT and two-phase AHT detection on state-of-the-art benchmark circuits. The experimental results show that with less than 4% area overhead, the proposed detection technique successfully detects capacitance-based AHTs.