An All Analog Temporal Power-supply Trojan to Subvert ECG Biometric Authentication

We present a novel hardware trojan that entirely originates and subverts in the analog domain. In the context of a System-on-a-chip (SoC) or System-in-a-package (SiP), it can compromise the system without any crossover or interaction with the digital subsystem, rendering it undetectable by existing digital detection methods. Potential adversaries include an untrusted designer, IP vendor, or system integrator. The trojan attacks via a temporal excursion applied on the power supply of the system. It is expressive at multiple levels, at the control of the attacker. It can be built entirely from existing analog dummy structures and incurs very low power and area overheads. We evaluate this trojan on an electrocardiogram (ECG) biometric analog front-end and demonstrate its ability, expressiveness, stealthiness, and controllability. It can cause false authentication and corruption of biometric data while remaining undetected by current analog test methodologies. Through this work, we highlight the critical need for development of detection strategies directly focused on such analog trojans.