  This report investigates the potential impact of a Trojan attack on power
conversion circuits, specifically a switching signal attack designed to trigger
a locking of the pulse width modulation (PWM) signal that goes to a power
field-effect transistor (FET). The first simulation shows that this type of
attack can cause severe overvoltage, potentially leading to functional failure.
The report proposes a solution using a large bypass capacitor to force signal
parity, effectively negating the Trojan circuit. The simulation results
demonstrate that the proposed solution can effectively thwart the Trojan
attack. However, several caveats must be considered, such as the size of the
capacitor, possible current leakage, and the possibility that the solution can
be circumvented by an adversary with knowledge of the protection strategy.
Overall, the findings suggest that proper protection mechanisms, such as the
proposed signal-parity solution, must be considered when designing power
conversion circuits to mitigate the risk of Trojan attacks.
