A Lightweight Robust Logic Locking Technique to Thwart Sensitization and Cone-Based Attacks

Logic locking is a new technique to prevent an integrated circuit from hardware Trojan, piracy, overbuilding, etc. Most of the well-known logic locking techniques are vulnerable to sensitization and cone based attacks. Though the existing techniques try to thwart these attacks, they are highly circuit topology dependent and require significant overhead. Therefore, this paper presents a new lightweight logic locking technique that effectively neutralizes the sensitization and cone based attacks. We further propose new multi key-input gates and a new replacement-based logic locking algorithm. The replacement of design gates with our multi key-input gates not only effectively prevents the key-sensitization and signal probability skew based removal attacks but also removes rare nets from design. On the other hand, our logic locking algorithm significantly increases the brute-force attempts against cone-based attack with minimum replacements by replacing the nodes which have the maximum number of fan-outs and paths to output nodes. We evaluate our technique using ISCAS benchmarks, and the results demonstrate that the proposed key-gates on average reduce 32 percent area-overhead over the XOR/MUX key-gates, whereas our algorithm on average doubles the effective key size while reducing 50 percent area overhead over the best-known technique.