On Preventing SAT Attack with Decoy Key-Inputs

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 outputs - unless 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.