Sensitivity Analysis of Locked Circuits

Globalization of integrated circuits manufacturing has led to increased security concerns, notably theft of intellectual property. In response, logic locking techniques have been developed for protecting designs, but many of these techniques have been shown to be vulnerable to SAT-based attacks. In this paper, we explore the use of Boolean sensitivity to analyze these locked circuits. We show that in typical circuits there is an inverse relationship between input width and sensitivity. We then demonstrate the utility of this relationship for deobfuscating circuits locked with a class of “provably secure” logic locking techniques. We conclude with an example of how to resist this attack, although the resistance is shown to be highly circuit dependent.