Attack of the Genes: Finding Keys and Parameters of Locked Analog ICs Using Genetic Algorithm

Hardware intellectual property (IP) theft is a major issue in today's globalized supply chain. To address it, numerous logic locking and obfuscation techniques have been proposed. While locking initially focused on digital integrated circuits (ICs), there have been recent attempts to extend it to analog ICs, which are easier to reverse engineer and to copy than digital ICs. In this paper, we use algorithms based on evolutionary strategies to investigate the security of analog obfuscation/locking techniques. We present a genetic algorithm (GA) approach which is capable of completely breaking a locked analog circuit by finding either its obfuscation key or its obfuscated parameters. We implement both the GA attack as well as a more naïve satisfiability modulo theory (SMT)-based attack on common analog benchmark circuits obfuscated by combinational locking and parameter biasing. We find that GA attack can unlock all the circuits using only the locked netlist and an unlocked chip in minutes. On the other hand, while the SMT attack converges faster, it requires circuit specification to execute and it also returns multiple keys that need to be brute-forced by a post-processing step. We also discuss how the GA attack can generalize to other recent analog locking techniques not tested in the paper.