Toward Optical Probing Resistant Circuits: A Comparison of Logic Styles and Circuit Design Techniques

Laser-assisted side-channel analysis techniques, such as optical probing (OP), have been shown to pose a severe threat to secure hardware. While several countermeasures have been proposed in the literature, they can either be bypassed by an attacker or require a modification in the transistor's fabrication process, which is costly and complex. In this work, firstly, we propose a formulation for the caliber of reflected light from OP. Secondly, we propose circuit design techniques and logic styles to alleviate OP attacks based on our formulation. Finally, we compare several logic families and circuit design techniques in terms of performance and OP security merits. In this regard, we perform simulations to compare the optical beam interaction between the different logic gates. By utilizing our proposed circuit design techniques and dual-rail logic (DRL), the signal-to-noise ratio (SNR) of the reflected light from OP is reduced significantly.