Using OFF-set only for Corrupting Circuit to Resist Structural Attack in CAC Locking
Hsiang-Chun Cheng, RuiJie Wang, TingTing Hwang · 2025
Corrupt-and-Correct (CAC) Logic Lockings [1]–[4] are state-of-the-art hardware security techniques designed to protect IC/IP designs from IP piracy, reverse engineering, overproduction, and unauthorized use. Although these techniques are resilient to SAT-based attacks, they remain vulnerable to structural attacks, which exploit structural traces left by the synthesis tool to recover the original form. In this paper, we will propose a novel method that uses only the OFF-set to corrupt the circuit. This approach helps the added circuitry better merge with the original circuit, thereby thwarting structural attacks while maintaining resilience to SAT-based attacks. Additionally, we demonstrate that our proposed method can incur less area overhead compared to previous locking methods in HIID [5]. Compared to SFLL-rem [4], our method can achieve comparable area overhead while effectively resisting structural attacks, including Valkyrie [6] and SPI attacks [7].