Modeling of Hardware Trojan-Based IEMI Backscattering System Using EM/Circuit Co-Simulation for Signal Intercepting

In this article, a novel security threat is presented, in which a Hardware Trojan (HT) inserted within the signal traces of an Off-the-shelf printed circuit board (PCB) causes electromagnetic information interception. This intercept activates HT only when intentional electromagnetic interference (IEMI) is applied externally. Without requiring a dedicated antenna design, it utilizes the PCB's signal traces as an Unintentional Antenna (UA) to backscattering signals, thereby enabling information interception through the modulated leakage electromagnetic waves. Typically, commercial PCBs that have undergone national-level electromagnetic compatibility (EMC) certification do not exhibit significant electromagnetic leakage. As a result, signal interception from this PCB theft are infeasible unless an HT is maliciously inserted and external IEMI is applied to interception mechanism. This study presents the first analysis of an information interception system in which a high-frequency electromagnetic wave is used to probe a commercial PCB containing an inserted HT. To investigate this phenomenon, Electromagnetic (EM)/Circuit Co-simulation was performed using three distinct simulation tools provided by Ansys. A bistatic backscattering system, comprising both transmitting and receiving antennas alongside a commercial PCB with an inserted HT, was modeled and analyzed using the Ansys Electronics Desktop Circuit simulator, the Ansys SIwave signal integrity analysis tool, and the Ansys HFSS full-wave electromagnetic solver. EM/Circuit co-simulation was adopted to reduce the time and cost associated with iterative experiments, facilitate simulations using commercial PCBs, and overcome the limitations of single-tool simulations in accurately calculating the transient response of leakage signals. The results obtained through EM/Circuit co-simulation provide critical insights into addressing HT-based electromagnetic information interception, highlighting the need for enhanced security measures in PCB design and EMC certification processes.