Increased Output Corruption and Structural Attack Resilience for SAT Attack Secure Logic Locking

Abstract

Listen

Translate article

Current out-of-cone logic locking methodologies provide resilience against the satisfiability (SAT) attack with minimal corruption of the outputs when comparing an activated and locked integrated circuit (IC). In addition, the structure of the modifications to the original logic leaks functional information of the circuit, which allows an adversary to determine the correct key. A novel logic locking methodology, CORruption adaptable logic locking (CORALL), is introduced in this article that provides increased security against the SAT attack for modified logic cones that require a large corruption of the primary outputs of the circuit, where the corruption is quantified by comparing between an activated and locked state of the IC. In addition, the modifications to the logic cone utilized by CORALL provide increased resilience against structural attacks. The CORALL architecture increases the number of iterations required to successfully execute a SAT attack for a flip function with 20 inputs by 34.41× over SFLL-HD n/4 and 82.36× over SFLL-Flex. In addition, a protected-cube selection process based on iterative cofactors is introduced, which provides varying logical functions of the perturb unit and maps portions of the logic of the perturb unit into the look-up tables (LUTs) of the CORALL architecture. The variation in the logical functions implemented by the perturb unit and the mapped functionality of the perturb unit into a LUT provide resistance to all current structural attacks on out-of-cone logic locking techniques.