A Neural Network-Based Cognitive Obfuscation Toward Enhanced Logic Locking

Logic obfuscation is introduced as a pivotal defense against multiple hardware threats on integrated circuits (ICs), including reverse engineering (RE) and intellectual property (IP) theft. The effectiveness of logic obfuscation is challenged by recently introduced Boolean satisfiability (SAT) attack and its variants. A plethora of counter measures have also been proposed to thwart the SAT attack. Irrespective of the implemented defense against SAT attacks, large power, performance, and area overheads are seen to be indispensable. In contrast, we propose a cognitive solution, which is a neural network (NN)-based SAT-hard clause translator, SATConda, that incurs a minimal area and power overhead while preserving the original functionality with enhanced security. SATConda is incubated with a SAT-hard clause generator that translates the existing conjunctive normal form (CNF) through minimal perturbations, such as the inclusion of pair of inverters or buffers or adding new lightweight SAT-hard block depending on the provided CNF. For efficient SAT-hard clause generation, SATConda is equipped with a multilayer NN that first learns the dependencies of features (literals and clauses), followed by a long short-term memory (LSTM) network to validate and backpropagate the SAT-hardness for better learning and translation. Our proposed SATConda is evaluated on ISCAS’85 and ISCAS’89 benchmarks and is seen to successfully defend against multiple state-of-the-art SAT attacks devised for hardware RE. In addition, we also evaluate our proposed SATConda’s empirical performance against MiniSAT, Lingeling, and Glucose SAT solvers that form the base for numerous existing deobfuscation SAT attacks.