Hardware Obfuscation of Digital FIR Filters

TL;DR

This paper introduces a hardware obfuscation technique for digital FIR filters that protects their coefficients from reverse engineering by hiding them among decoys, ensuring security with minimal hardware overhead.

Contribution

It presents a novel filter design method that conceals coefficients using decoys, enhancing security against reverse engineering and oracle-less attacks while maintaining hardware efficiency.

Findings

The technique effectively hides filter coefficients among decoys.

Experimental results show increased resilience to reverse engineering attacks.

Hardware complexity remains competitive with existing methods.

Abstract

A finite impulse response (FIR) filter is a ubiquitous block in digital signal processing applications. Its characteristics are determined by its coefficients, which are the intellectual property (IP) for its designer. However, in a hardware efficient realization, its coefficients become vulnerable to reverse engineering. This paper presents a filter design technique that can protect this IP, taking into account hardware complexity and ensuring that the filter behaves as specified only when a secret key is provided. To do so, coefficients are hidden among decoys, which are selected beyond possible values of coefficients using three alternative methods. As an attack scenario, an adversary at an untrusted foundry is considered. A reverse engineering technique is developed to find the chosen decoy selection method and explore the potential leakage of coefficients through decoys. An oracle-less attack is also used to find the secret key. Experimental results show that the proposed technique can lead to filter designs with competitive hardware complexity and higher resiliency to attacks with respect to previously proposed methods.