A Novel Probability-Based Logic-Locking Technique: ProbLock

Integrated circuit (IC) piracy and overproduction are serious issues that threaten the security and integrity of a system. Logic locking is a type of hardware obfuscation technique where additional key gates are inserted into the circuit. Only the correct key can unlock the functionality of that circuit; otherwise, the system produces the wrong output. In an effort to hinder these threats on ICs, we have developed a probability-based logic-locking technique to protect the design of a circuit. Our proposed technique, called “ProbLock”, can be applied to both combinational and sequential circuits through a critical selection process. We used a filtering process to select the best location of key gates based on various constraints. Each step in the filtering process generates a subset of nodes for each constraint. We also analyzed the correlation between each constraint and adjusted the strength of the constraints before inserting key gates. We tested our algorithm on 40 benchmarks from the ISCAS ’85 and ISCAS ’89 suites. We evaluated ProbLock against a SAT attack and measured how long the attack took to successfully generate a key value. The SAT attack took longer for most benchmarks using ProbLock which proves viable security in hardware obfuscation.

Lockit: A Logic Locking Automation Software

The significant rise in the cost of manufacturing nanoscale integrated circuits (ICs) has led the majority of IC design companies to outsource the fabrication of their products to other companies, often located in different countries. The multinational nature of the hardware supply chain has led to a host of security threats, including IP piracy, IC overproduction, and Trojan insertion. To combat these, researchers have proposed logic locking techniques to protect the intellectual properties of the design and increase the difficulty of malicious modification of its functionality. However, the adoption of logic locking approaches has been rather slow due to the lack of integration with the IC production process and the lack of efficacy of existing algorithms. This work automates the logic locking process by developing software using Python that performs the locking on a gate-level netlist, which can be integrated with the existing digital synthesis tools. Analysis of the latest logic locking algorithms has demonstrated that the SFLL-HD algorithm is one of the most secure and versatile when trading-off levels of protection against different types of attacks and was thus selected for implementation. The presented tool can also be expanded to incorporate the latest locking mechanisms to keep up with the fast-paced development in this field. The paper also presents a case study to demonstrate the functionality of the tool and how it could be used to explore the design space and compare different locking solutions.