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Cute-Lock: Behavioral and Structural Multi-Key Logic Locking Using Time Base Keys

Kevin Lopez, Amin Rezaei

TL;DR

This work addresses the security risks of outsourced semiconductor manufacturing by introducing Cute-Lock, a time-based multi-key logic locking framework deployable at both RTL behavioral and gate-level structural representations. It presents two variants, Cute-Lock-Beh and Cute-Lock-Str, combining a counter-driven key sequence with a multiplexor-tree architecture to enforce correct operation only under a specific key schedule, thereby confounding oracle-guided SAT, dataflow, and removal attacks. The authors validate the approach across extensive benchmarks, demonstrating strong resilience against state-of-the-art attacks (NEOS, RANE, DANA, FALL) and showing favorable overheads, especially for larger circuits. The results suggest that Cute-Lock offers a practical, scalable solution for protecting hardware IP in the semiconductor supply chain, with potential extensions to broaden security coverage beyond current attack models.

Abstract

The outsourcing of semiconductor manufacturing raises security risks, such as piracy and overproduction of hardware intellectual property. To overcome this challenge, logic locking has emerged to lock a given circuit using additional key bits. While single-key logic locking approaches have demonstrated serious vulnerability to a wide range of attacks, multi-key solutions, if carefully designed, can provide a reliable defense against not only oracle-guided logic attacks, but also removal and dataflow attacks. In this paper, using time base keys, we propose, implement and evaluate a family of secure multi-key logic locking algorithms called Cute-Lock that can be applied both in RTL-level behavioral and netlist-level structural representations of sequential circuits. Our extensive experimental results under a diverse range of attacks confirm that, compared to vulnerable state-of-the-art methods, employing the Cute-Lock family drives attacking attempts to a dead end without additional overhead.

Cute-Lock: Behavioral and Structural Multi-Key Logic Locking Using Time Base Keys

TL;DR

This work addresses the security risks of outsourced semiconductor manufacturing by introducing Cute-Lock, a time-based multi-key logic locking framework deployable at both RTL behavioral and gate-level structural representations. It presents two variants, Cute-Lock-Beh and Cute-Lock-Str, combining a counter-driven key sequence with a multiplexor-tree architecture to enforce correct operation only under a specific key schedule, thereby confounding oracle-guided SAT, dataflow, and removal attacks. The authors validate the approach across extensive benchmarks, demonstrating strong resilience against state-of-the-art attacks (NEOS, RANE, DANA, FALL) and showing favorable overheads, especially for larger circuits. The results suggest that Cute-Lock offers a practical, scalable solution for protecting hardware IP in the semiconductor supply chain, with potential extensions to broaden security coverage beyond current attack models.

Abstract

The outsourcing of semiconductor manufacturing raises security risks, such as piracy and overproduction of hardware intellectual property. To overcome this challenge, logic locking has emerged to lock a given circuit using additional key bits. While single-key logic locking approaches have demonstrated serious vulnerability to a wide range of attacks, multi-key solutions, if carefully designed, can provide a reliable defense against not only oracle-guided logic attacks, but also removal and dataflow attacks. In this paper, using time base keys, we propose, implement and evaluate a family of secure multi-key logic locking algorithms called Cute-Lock that can be applied both in RTL-level behavioral and netlist-level structural representations of sequential circuits. Our extensive experimental results under a diverse range of attacks confirm that, compared to vulnerable state-of-the-art methods, employing the Cute-Lock family drives attacking attempts to a dead end without additional overhead.

Paper Structure

This paper contains 21 sections, 4 figures, 5 tables.

Table of Contents

  1. Introduction
  2. Background and Related Work
  3. Logic Locking Techniques
  4. Logic Locking Attacks
  5. Multi-Key Approaches
  6. Cute-Lock Family
  7. Terminology
  8. Behavioral Solution
  9. Structural Solution
  10. Experimental Results
  11. Algorithm Validation
  12. Behavioral Solution
  13. Structural Solution
  14. Logic Attacks Evaluation
  15. Behavioral Solution
  16. ...and 6 more sections

Figures (4)

  • Figure 1: Cute-Lock-Beh STG example
  • Figure 2: Cute-Lock-Str STG & STT example
  • Figure 3: Cute-Lock-Strmux tree example
  • Figure 4: Overhead comparison of Cute-Lock-Str with DK-Lock DKLock