A Physical Design Flow against Front-side Probing Attacks by Internal Shielding

Security-critical applications on integrated circuits (ICs) are threatened by probing attacks that extract sensitive information assisted with focused ion beam (FIB)-based circuit edit. Existing countermeasures, such as active shield, analog shield, and $t$ -private circuit, have proven to be inefficient and provide limited resistance against probing attacks without taking FIB capabilities into consideration. In this article, we propose an FIB-aware anti-probing physical design flow, which considers FIB capabilities and utilizes computer-aided design (CAD) tools, to automatically reduce the probing attack vulnerability of an IC’s security-critical nets with minimal extra design effort. The floor-planning and routing of the design are constrained by incorporating three new steps in the conventional physical design flow, so that security-critical nets are protected by internal shield nets with low overhead. Results show that the proposed technique can reduce the vulnerable area exposed to probing on security-critical nets by 100% with all critical nets fully protected for both advanced encryption standard (AES) and data encryption standard (DES) modules. The timing, area, and power overheads are less than 3% per module, which would be negligible in a system-on-chip (SoC) design.