Threshold-Dependent Camouflaged Cells to Secure Circuits Against Reverse Engineering Attacks

TL;DR

This paper introduces a novel IC camouflaging technique using threshold voltage-dependent cells that are structurally identical, providing robust protection against reverse engineering even with advanced imaging techniques.

Contribution

The work presents a new camouflaging approach based on threshold voltages, differing from look-alike cells by being structurally identical, enhancing security against reverse engineering.

Findings

Cells operate reliably across all PVT corners.

Simulations show effective camouflage of large netlists.

Technique is cost-effective and robust.

Abstract

With current tools and technology, someone who has physical access to a chip can extract the detailed layout of the integrated circuit (IC). By using advanced visual imaging techniques, reverse engineering can reveal details that are meant to be kept secret, such as a secure protocol or novel implementation that offers a competitive advantage. A promising solution to defend against reverse engineering attacks is IC camouflaging. In this work, we propose a new camouflaging technique based on the threshold voltage of the transistors. We refer to these cells as threshold dependent camouflaged cells. Our work differs from current commercial solutions in that the latter use look-alike cells, with the assumption that it is difficult for the reverse engineer to identify the cell's functionality. Yet, if a structural distinction between cells exists, then these are still vulnerable, especially as reverse engineers use more advanced and precise techniques. On the other hand, the proposed threshold dependent standard cells are structurally identical regardless of the cells' functionality. Detailed circuit simulations of our proposed threshold dependent camouflaged cells demonstrate that they can be used to cost-effectively and robustly camouflage large netlists. Corner analysis of process, temperature, and supply voltage (PVT) variations show that our cells operate as expected over all PVT corners simulated.