Locked Circuit Indistinguishability: A Notion of Security for Logic Locking

Mohamed El Massad, Nahid Juma, Jonathan Shahen, Mariana Raykova, Siddharth Garg, Mahesh Tripunitara

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We address logic locking, a mechanism for securing digital Integrated Circuits (ICs) from piracy by untrustworthy foundries. We discuss previous work and the state-of-the-art, and observe that, despite more than a decade of research that has gone into the topic (resulting in both powerful attacks and subsequent defenses), there is no consensus on what it means for a particular locking mechanism to be secure. This paper attempts to remedy this situation. Specifically, it formulates a definition of security for a logic locking mechanism based on indistinguishability and relates the definition to security from actual attackers in a precise and unambiguous manner. We then describe a mechanism that satisfies the definition, thereby achieving (provable) security from all prior attacks. The mechanism assumes the existence of both a puncturable pseudorandom function family and an indistinguishability obfuscator, two cryptographic primitives that exist under well-founded assumptions. The mechanism builds upon the Stripped-Functionality Logic Locking (SFLL) framework, a state-of-the-art family of locking mechanisms whose potential for ever achieving security is currently in question. Along the way, partly as motivation, we present additional results, such as a reason founded in average-case complexity for why benchmark circuits locked with a prior scheme are susceptible to the well-known SAT attack against such schemes, and why provably thwarting the SAT attack is insufficient as a meaningful notion of security for logic locking.

Original languageEnglish (US)
Title of host publicationProceedings - 2022 IEEE 35th Computer Security Foundations Symposium, CSF 2022
PublisherIEEE Computer Society
Number of pages16
ISBN (Electronic)9781665484176
StatePublished - 2022
Event35th IEEE Computer Security Foundations Symposium, CSF 2022 - Haifa, Israel
Duration: Aug 7 2022Aug 10 2022

Publication series

NameProceedings - IEEE Computer Security Foundations Symposium
ISSN (Print)1940-1434


Conference35th IEEE Computer Security Foundations Symposium, CSF 2022

ASJC Scopus subject areas

  • General Engineering


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