Visible to the public LL-ATPG: Logic-Locking Aware Test Using Valet Keys in an Untrusted Environment

TitleLL-ATPG: Logic-Locking Aware Test Using Valet Keys in an Untrusted Environment
Publication TypeConference Paper
Year of Publication2021
AuthorsRahman, M Sazadur, Li, Henian, Guo, Rui, Rahman, Fahim, Farahmandi, Farimah, Tehranipoor, Mark
Conference Name2021 IEEE International Test Conference (ITC)
KeywordsCosts, design for testability, Human Behavior, Logic gates, logic locking, Manufacturing, Manufacturing test, pattern locks, pubcrawl, resilience, Resiliency, reverse engineering, Scalability, Semiconductor device modeling, Supply chains, system-on-chip, untrusted foundry
AbstractThe ever-increasing cost and complexity of cutting-edge manufacturing and test processes have migrated the semiconductor industry towards a globalized business model. With many untrusted entities involved in the supply chain located across the globe, original intellectual property (IP) owners face threats such as IP theft/piracy, tampering, counterfeiting, reverse engineering, and overproduction. Logic locking has emerged as a promising solution to protect integrated circuits (ICs) against supply chain vulnerabilities. It inserts key gates to corrupt circuit functionality for incorrect key inputs. A logic-locked chip test can be performed either before or after chip activation (becoming unlocked) by loading the unlocking key into the on-chip tamperproof memory. However, both pre-activation and post-activation tests suffer from lower test coverage, higher test cost, and critical security vulnerabilities. To address the shortcomings, we propose LL-ATPG, a logic-locking aware test method that applies a set of valet (dummy) keys based on a target test coverage to perform manufacturing test in an untrusted environment. LL-ATPG achieves high test coverage and minimizes test time overhead when testing the logic-locked chip before activation without sharing the unlocking key. We perform security analysis of LL-ATPG and experimentally demonstrate that sharing the valet keys with the untrusted foundry does not create additional vulnerability for the underlying locking method.
Citation Keyrahman_ll-atpg_2021