Linear Approximation and Differential Attacks on Logic Locking Techniques

Logic locking is a protection technique for out-sourced integrated circuit (IC) designs that thwarts IC piracy and IC counterfeiting by untrusted foundries. In logic locking, the key gates used for masking the circuit adds to the area overhead of the original circuit, and hence increases the power consumption too. In this paper, we mount linear approximation attacks and differential attacks on random logic locking (RLL), fault-analysis based logic locking (FLL), and strong logic locking (SLL) techniques. We present our results on ISCAS'85 benchmark circuits. In linear approximation attack, the combinatorial blocks partitioned and expressed as linear expressions to derive a relation between the key inputs and the primary inputs of the circuit. In differential attacks, we could recover the embedded secret key in device with attack effort lesser than exhaustive search attack.