Hardware IP Protection Using Logic Encryption and Watermarking

Abstract

Logic encryption is a popular Design-for-Security(DfS) solution that offers protection against the potential adversaries in the third-party fab labs and end-users. However, over the years, logic encryption has been a target of several attacks, especially Boolean satisfiability attacks. This paper exploits SAT attack’s inability of deobfuscating sequential circuits as a defense against it. We propose several strategies capable of preventing the SAT attack by obfuscating the scan-based Design-for-Testability (DfT) infrastructure. Unlike the existing SAT-resilient schemes, the proposed techniques do not suffer from poor output corruption for wrong keys. This paper also offers various probable solutions for inserting the key-gates into the circuit that ensures protection against numerous other attacks, which exploit weak key-gate locations. Along with several gate-level obfuscation strategies, this paper also presents a Cellular Automata (CA) guided FSM obfuscation strategy to offer protection at a higher abstraction level, that is, RTL-level. For all the proposed schemes, rigorous security analysis against various attacks evaluates their strengths and limitations. Testability analysis also ensures that none of the proposed techniques hamper the basic testing properties of the ICs. We also present a CA-based FSM watermarking strategy that helps to detect potential theft of the designer’s IP by any adversary.