Hardware security and trust: Logic locking as a design-for-trust solution

Ever-increasing design complexity and the skyrocketing cost of setting up a foundry have led to the globalization of the integrated circuit (IC) supply chain. A globalized and distributed IC supply fosters security threats such as reverse engineering, piracy, and hardware Trojans, and forces the stakeholders to revisit the trust at various steps in the IC design and fabrication flow. Among the ensemble of solutions proposed to address hardware-related trust issues, logic locking has gained significant interest from the research community. A series of defense techniques and attacks have been developed over the past few years. This chapter presents a comprehensive survey of recent research efforts in the field of logic locking. The emphasis is on the subtle difference between the logic locking attacks/countermeasures in terms of the threat models employed and strengths/vulnerabilities of existing logic locking techniques.