SPARTA: A Laser Probing Approach for Trojan Detection

Integrated circuits (ICs) fabricated at untrusted foundries are vulnerable to hardware Trojan insertion. Trojans can be inserted into design files by modifying existing functionality or inserting additional circuitry into unused areas. Checking for the existence of Trojans either requires design-level modification or a complex test process. Unfortunately, the detection confidence using existing techniques is low, while they require a significant increase in verification effort, making them inapplicable to complex circuits due to aggressive time-to-market constraints. On the other hand, for a high confidence detection of Trojans, an exhaustive inspection may be required using destructive reverse-engineering techniques. However, such methods are quite expensive, render the device unusable, and are very time-consuming. In this work, we propose SPARTA, a non-destructive laser probing approach for Trojan detection, which detects sequential hardware Trojans by comparing clock activity within a fabricated IC with the original clock tree created in the design phase. SPARTA does not require any golden samples, but rather the golden design. SPARTA is based upon creating a 2-dimensional frequency map of the backside silicon using electro-optical frequency mapping (EOFM), which exposes the activity of clocked elements in the IC. The measurements are then compared with the expected sequential activity based on the original clock tree identified in the IC to detect all additions, subtractions, or modifications to sequential elements with sub-micron spatial resolution and its efficiency is demonstrated on a 28nm device.