Evaluating the Indistinguishability of Logic Locking using K-Cut Enumeration and Boolean Matching

TL;DR

This paper introduces a new evaluation method for logic locking security based on K-cut enumeration and Boolean matching, revealing that many locks lack true indistinguishability and are vulnerable to analysis.

Contribution

The authors propose a novel K-cut based evaluation approach to assess the indistinguishability of logic locking techniques, bridging the gap between theory and practical security analysis.

Findings

Up to 92% accuracy in identifying locked designs

Many logic locks do not achieve indistinguishability

Resynthesis does not significantly improve security

Abstract

Logic locking as a solution for semiconductor intellectual property (IP) confidentiality has received considerable attention in academia, but has yet to produce a viable solution to protect against known threats. In part due to a lack of rigor, logic locking defenses have been historically short-lived, which is an unacceptable risk for hardware-based security solutions for critical systems that may be fielded for decades. Researchers have worked to map the concept of cryptographic indistinguishability to logic locking, as indistinguishability provides strong security guarantees. In an effort to bridge theory and practice, we highlight recent efforts that can be used to analyze the indistinguishability of logic locking techniques, and propose a new method of evaluation based on comparing distributions of $k$-cuts, which is akin to comparing against a library of sub-functions. We evaluate our approach on several different classes of logic locking and show up to 92% average accuracy in correctly identifying which design was locked, even in the presence of resynthesis, suggesting that the evaluated locks do not provide indistinguishability.