Programmable Gates Using Hybrid CMOS-STT Design to Prevent IC Reverse Engineering

This article presents a rigorous step towards design-for-assurance by introducing a new class of logically reconfigurable design resilient to design reverse engineering. Based on the non-volatile spin transfer torque (STT) magnetic technology, we introduce a basic set of non-volatile reconfigurable Look-Up-Table (LUT) logic components (NV-STT-based LUTs). An STT-based LUT with a significantly different set of characteristics compared to CMOS provides new opportunities to enhance design security yet makes it challenging to remain highly competitive with custom CMOS or even SRAM-based LUT in terms of power, performance, and area. To address these challenges, we propose several algorithms to select and replace custom CMOS gates with reconfigurable STT-based LUTs during design implementation such that the functionality of STT-based components and therefore the entire design cannot be determined in any manageable time, rendering any design reverse engineering attack ineffective. Our study, conducted on a large number of standard circuit benchmarks, concludes significant resiliency of hybrid STT-CMOS circuits against various types of attacks. Furthermore, the selection algorithms on average have a small impact on the performance of the circuit. We also tested these techniques against satisfiability attacks developed recently and show that these techniques also render more advanced reverse-engineering techniques computationally infeasible.