An Effective Application of Obfuscated TMR to Tackle Hardware Trojans

Redundancy-based techniques are used in the literature to neutralize the effects of hardware Trojan horses (HTHs). However, the available techniques assume that HTHs cannot be inserted into the replicated logic, without introducing recognizable changes in the side effects of the circuit. In this paper, we discuss the limitations of this assumption. We demonstrate that fault-tolerant techniques should be enhanced by obfuscation methods to be actually effective, and we propose a novel obfuscated TMR (Triple Modular Redundancy) to prove the concept. We evaluated the effectiveness of our approach on ISCAS benchmarks. The results show that Trojans would incur about 18% higher detection risk in average, if attackers try to deceive the obfuscated TMR.