Investigating SRAM PUFs in large CPUs and GPUs

TL;DR

This paper explores the presence of physically unclonable functions (PUFs) in common PC components like CPUs and GPUs, discovering usable PUFs in Nvidia GPUs which could enhance hardware security and identification.

Contribution

It introduces novel tools and methods to detect intrinsic PUFs in standard PC hardware components not originally designed for this purpose.

Findings

Usable PUFs found in Nvidia GPUs

Non-random behavior in CPU registers and cache

Limited PUFs in some components

Abstract

Physically unclonable functions (PUFs) provide data that can be used for cryptographic purposes: on the one hand randomness for the initialization of random-number generators; on the other hand individual fingerprints for unique identification of specific hardware components. However, today's off-the-shelf personal computers advertise randomness and individual fingerprints only in the form of additional or dedicated hardware. This paper introduces a new set of tools to investigate whether intrinsic PUFs can be found in PC components that are not advertised as containing PUFs. In particular, this paper investigates AMD64 CPU registers as potential PUF sources in the operating-system kernel, the bootloader, and the system BIOS; investigates the CPU cache in the early boot stages; and investigates shared memory on Nvidia GPUs. This investigation found non-random non-fingerprinting behavior in several components but revealed usable PUFs in Nvidia GPUs.