Outsourcing design and fabrication process has become a recent trend in the semiconductor industry mainly in the manufacturing of integrated circuits (IC) to increase their economic benefits. A motivated adversary who intends to destroy or modify the function of the chip can take advantage of this process, which can have serious consequences. Every industry uses electronic circuits in their systems. Hence a modified function can lead to disastrous results when the system containing it is put in use. This modification can be termed as Trojans. Hardware Trojan is an addition of extra circuitry or an intentional modification of the integrated circuits, which modifies the functionality of the circuit. It is completely characterized by its physical representation and its behavior. The circuit malfunctioning happens only when the trojan circuit gets triggered. A hardware Trojan has two parts namely Trojan trigger and Trojan payload . The part of the circuit that enables the triggering condition is called the Trojan trigger and the entire activity that a Trojan executes when it is triggered is called the Trojan payload. Trojan circuits have stealthy nature and are triggered in rare conditions. This makes Hardware Trojan detection, an extremely challenging problem.
D. K. Karunakaran and Mohankumar, N., “Malicious combinational Hardware Trojan detection by Gate Level Characterization in 90nm technology”, in Computing, Communication and Networking Technologies (ICCCNT), 2014 International Conference on, 2014.