Security against hardware Trojan through a novel application of design obfuscation
Rajat Subhra Chakraborty, Swarup Bhunia · 2009
Malicious hardware Trojan circuitry inserted in safety-critical applications is a major threat to national security. In this work, we propose a novel application of a key–based obfus-cation technique to achieve security against hardware Tro-jans. The obfuscation scheme is based on modifying the state transition function of a given circuit by expanding its reachable state space and enabling it to operate in two dis-tinct modes – the normal mode and the obfuscated mode. Such a modification obfuscates the rareness of the internal circuit nodes, thus making it difficult for an adversary to insert hard-to-detect Trojans. It also makes some inserted Trojans benign by making them activate only in the obfus-cated mode. The combined effect leads to higher Trojan detectability and higher level of protection against such at-tack. Simulation results for a set of benchmark circuits show that the scheme is capable of achieving high levels of security at modest design overhead.