Secure Control Logic Design for Dual Key Logic Locking

While numerous methods aim to secure circuits using a globally protected key, they remain vulnerable to various oracle-guided attacks capable of extracting the correct key. Recently, a dual key logic locking method has emerged to enhance security for sequential circuits, utilizing two distinct keys applied to one set of key inputs at different intervals. However, further improvements can be made to the controller of this dual key method. In this paper, we propose a novel controller design for the dual key logic locking, integrating the control logics of both the activation phase and the functional phase into a unified finite state machine. This approach not only simplifies the control logic design but also strengthens the security of the controller. Experimental results consistently demonstrate the effectiveness of our proposed approach in practical scenarios.