On Preventing SAT Attack with Decoy Key-Inputs

Abstract

The globalized supply chain in the semiconductor industry raises several security concerns such as IC overproduction, intellectual property piracy and design tampering. Logic locking has emerged as a Design-for-Trust countermeasure to address these issues. Original logic locking proposals provide a high degree of output corruption -i.e., errors on circuit outputsunless it is unlocked with the correct key. This is a prerequisite for making a manufactured circuit unusable without the designer's intervention. Since the introduction of SAT-based attacks -highly efficient attacks for retrieving the correct key from an oracle and the corresponding locked design -resulting design-based countermeasures have compromised output corruption for the benefit of better resilience against such attacks. Our proposed logic locking scheme, referred to as SKG-Lock, aims to thwart SAT-based attacks while maintaining significant output corruption. The proposed provable SAT-resilience scheme is based on the novel concept of decoy key-inputs. Compared with recent related works, SKG-Lock provides higher output corruption, while having high resistance to evaluated attacks.

Hybrid Protection of Digital FIR Filters

“…Moreover, these multiplier blocks under an architecture including a multiplier are locked by prominent logic locking methods, namely, RLL [28] and the SAT-resilient methods of AntiSAT [33], SARLock [32], SFLL [23], CASLock [34], and SKGLock [36]. In this case, the multiplier block described at RTL is initially synthesized and its gate-level netlist is obtained, and then, this netlist is locked.…”

“…However, the satisfiability (SAT)-based attack [31] overcame all the defenses existing at that time. To thwart the SAT-based attack and its variants, circuits have been locked using a point function that forces these attacks to explore an exponential number of queries [23], [32]- [36]. Moreover, the obfuscation of a locked design is considered in [37].…”

“…We note that since the point function is described at RTL, the synthesis tool shapes its circuit based on the given synthesis parameters. Thus, its realization does not have a regular structure like logic locking methods of [33], [34], [36].…”

SKG-Lock+: A Provably Secure Logic Locking SchemeCreating Significant Output Corruption

“…In line with proposals based on improved point-function structures, which aim at increasing output corruption, we have proposed SK-Lock in [24]. SKG-Lock+ improves on this version, as will be detailed in this section.…”

“…This research has also been coupled with improvements in attacks, mimicking an extremely prolific cat and mouse game, which motivates all the more the proposal of new protection methods, while making this task even more challenging. To address the limitations of previous schemes, we proposed SKG-Lock [24], featuring the characteristics of causing corruption at multiple signals with different corruptibilities. In this paper, we present SKG-Lock+, which also provides high security against attacks while further improving corruption.…”