A Secure Camouflaged Threshold Voltage Defined Logic Family

A myriad of security vulnerabilites can be exposed via the reverse engineering of the integrated circuits contained in electronics systems. The goal of IC reverse engineering is to uncover the functionality and internal structure of the chip via techniques such as depackaging/delayering, high-resolution imaging, probing, and side-channel examination. With this knowledge, an attacker can more efficiently mount various attacks, clone/counterfeit the design possibly with hardware Trojans inserted, and discover trade secrets. We propose a gate camouflaging technique that relies on the usage of different threshold voltage transistors, but with identical layouts, to determine the logic gate function. In our threshold voltage defined (TVD) camouflaging technique, every TVD logic gate has the same physical structure and is one time mask programmed with different threshold implants for different boolean functionality. We design and implement TVD logic gates in an industrial 65nm bulk CMOS process. Using post-layout extracted simulation, we evaluate the logic style for VLSI overheads (area, power, delay) versus conventional logic, for process variablity robustness, and for various security metrics. Further, we evaluate the macro block overheads for ISCAS benchmark designs under various levels of TVD gate replacement upto and including 100% replacement. TVD logic gates are found to be CMOS process compatible, low overhead, and to increase security against various forms of attacks.