An Enhanced Logic Encryption Method with a Fully Correlated Key Interdependency Block

Logic encryption, as a hardware security technique, can protect integrated circuits (ICs) by inserting additional gates. The inserted gates guarantee that predefined outputs are only generated when correct key inputs are provided, preventing IC counterfeiting, intellectual property (IP) theft, and IC overproduction. To evaluate the logic encryption’s robustness, two major criteria are usually utilized, which are (1) the interdependency between the keys and (2) the output corruption against attacks, including path sensitization attack, SATbased attack, hill-climbing attack, etc. However, the majority of existing logic encryption methods emphasize one criterion over the other. In this paper, an enhanced logic encryption method with a fully correlated key interdependency block is proposed. The method enhances the interdependency of keys and determines the locations of key-gates utilizing a rare node analysis method. Experimental results validate that the proposed method can withstand path sensitization attack and ensure 50% Hamming distance with reasonable design overheads.