LOOPLock 3.0: A Robust Cyclic Logic Locking Approach

Cyclic logic locking is a cutting-edge hardware security method developed to defend against SAT Attack. It introduces cycles into the original circuit, which can cause the circuit to either get trapped in an endless loop or generate incorrect outputs if an incorrect key is used. Recently, a new cyclic logic locking method called LOOPLock 2.0 was proposed. Its primary feature is that the circuit retains its cyclic structure regardless of whether the correct key vector is applied or not. However, LOOPLock 2.0 can still be successfully attacked using locking structure analysis in the state-of-the-art. As a result, this paper presents a more robust cyclic logic locking approach LOOPLock 3.0 to counteract state-of-the-art attacks. The experimental results validate the effectiveness of the proposed approach.