Data Flow Obfuscation: A New Paradigm for Obfuscating Circuits

In this article, unlike almost all state-of-the-art obfuscation solutions that focus on functional/logic obfuscation, we introduce a new paradigm, called data flow obfuscation, which exploits the essence of asynchronicity. In data flow obfuscation, by benefiting from the handshaking mechanism of asynchronous circuits, the system's FFs/latches will operate out of sync. Hence, the adversary has no sufficient knowledge to apply unrolling/BMC. Also, due to the inherited asynchronicity, the exact time of writing/capturing data into/from the scan chain becomes hidden. Hence, the SAT attack cannot be applied even while scan chain access is open. Moreover, our new proposed paradigm creates stateful/oscillating combinational cycles into the design which extensively boosts the difficulty of modeling this technique. We also demonstrate how data flow obfuscation could easily be integrated with any circuit at low overhead while there is no limitation such as compromising test flow.