Locked-by-Design: Enhancing White-box Logic Obfuscation with Effective Key Mutation
Leon Li, Alex Orailoğlu · 2024
This paper proposes an obfuscation technique that thwarts functional reverse engineering despite the operational netlist being completely visible to the attacker. Central to this approach is the recognition that reverse engineering necessitates not only the recovery of an operational netlist but also the extraction of functional understandings from it to drive specific illegitimate applications. The proposed approach applies self-generated and mutating keys to obfuscate Finite State Machines (FSMs), forcing attackers to perform complex sequential analysis to learn even the simplest aspects of a design’s functionality. This work examines the impact of key mutation operations on the effectiveness and efficiency of obfuscation. It suggests an enhanced key mutation scheme capable of significantly reducing the implementation overheads without compromising attack resilience. The experimental results show that the proposed obfuscation algorithm leads to drastic overhead improvements and demonstrates strong resilience to sequential SAT attacks and functional reverse engineering.