Digital Security by Design: Physical Unclonable Functions - Gavin McWilliams, Queen's University Belfast
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The document discusses Physical Unclonable Functions (PUFs), which use manufacturing variations to create unique digital fingerprints for chips to enhance digital security. It classifies PUFs into weak and strong categories, with respective applications including identity generation, non-volatile key storage, and challenge-response authentication. Additionally, it outlines practical implementations of PUFs using Xilinx devices and ARM Cortex processors.
Digital Security by Design: Physical Unclonable Functions - Gavin McWilliams, Queen's University Belfast
- 1. DIGITAL SECURITY BY DESIGN WORKSHOP GAVIN MCWILLIAMS Director of Engineering 26 September 2019
- 3. What is a PUF? PUF 000000000000 70db46a1208fe753 29d3a6720fc43805 39e01f6290ac89d0 A PUF (Physical Unclonable Function) is a digital circuit that uses manufacturing process variations to generate a unique digital fingerprint. No two chips should give the same response when supplied with the same challenge. Oxide Doping Feature size Process Variations
- 4. PUF Classification: Weak Vs Strong Weak PUF • Typically have no (or one fixed) challenge - e.g. SRAM PUF, Butterfly PUF. • Assumed an attacker cannot access the responses of “Weak” PUFs as one or few CRPs could be used to build a model of the security system • Applications include: - Identity generation - RNG seed - Non volatile key storage - Hardware root of trust - Anti-Cloning
- 5. PUF Classification: Weak Vs Strong Strong PUF • May have many possible challenge response pairs (CRPs), e.g. Arbiter PUF. • With access to the CRPs, it should be infeasible to model the system and determine the CRPs of a strong PUF • Applications include: - Challenge-response authentication - Anti-cloning
- 6. FPGA Testbed: 240 Xilinx Zynq devices (ARM Cortex-A9 + Artix-7 FPGA) www.csit.qub.ac.uk 6
- 7. Software PUF • SRAM PUF on ARM Cortex-M4 processors www.csit.qub.ac.uk 7 Uniqueness Source:https://www.arm.com/assets Source: drprem.com Ideal uniqueness = 0.5
- 8. Key Storage
- 10. Secure Boot • Boot without trusting Xilinx • Bitstream encryption without blowing fuses • Or battery backed storage • Only helper data changes between devices, the key can be set the same