Industrial Control Authentication Using PUF-Based Device Keys

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Solution Overview

Problem

Industrial automation environments face security vulnerabilities due to counterfeit industrial control products, which can go undetected and compromise the system, as existing authentication solutions rely on secret keys that can be extracted or modified.

Innovation Solution

The use of a physical unclonable function (PUF) to generate a unique secret key based on the device's atomic structure, eliminating the need to store the private key on the device and providing a digital fingerprint for authentication, with a certificate signed by the OEM and verified through cryptographic means.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If secret keys are stored on the device for authentication, then authentication can be performed, but the security is compromised because the keys can be extracted or modified

Engineering Contradiction:
Improveauthentication securityVSAvoidkey extraction risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the secret key from the device entirely, eliminating the security vulnerability of stored keys. Instead of storing private keys on the device, the system uses public key infrastructure where only public keys and certificates are stored on the device, while private keys remain securely on the authentication server.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces certificates and public key infrastructure as intermediaries between the device and authentication server. The device communicates its identity through certificates signed by trusted authorities, eliminating the need for direct secret key storage while maintaining authentication capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If physical unclonable functions are used to generate dynamic keys, then security against counterfeiting is improved, but device complexity increases

Engineering Contradiction:
Improvecounterfeiting preventionVSAvoidPUF implementation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical or electronic key storage systems with physical unclonable functions that leverage inherent physical characteristics of the device (such as manufacturing variations in silicon) to generate unique identifiers and cryptographic keys, eliminating the need for complex key management hardware.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If private keys are not stored on the device, then security is enhanced, but the authentication process becomes more complex

Engineering Contradiction:
Improvesecurity against backdoor attacksVSAvoidauthentication process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent performs preliminary actions during device manufacturing by embedding certificates and public keys into the device before deployment. This preliminary provisioning simplifies the runtime authentication process, as the device only needs to present its pre-configured credentials rather than managing complex key pairs dynamically.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4156600A1Use of physical unclonable functions to prevent counterfeiting of industrial control products
Publication Date: 2023.03.29 ROCKWELL AUTOMATION TECH INC
  • EP4156600A1 patent drawingFigure 1
  • EP4156600A1 patent drawingFigure 2
  • EP4156600A1 patent drawingFigure 3

AI summary

Techniques for authenticating industrial devices in an industrial automation environment are disclosed herein. In at least one implementation, a physical unclonable function response of an industrial device is extracted. The industrial device transmits a security certificate signed by a certificate authority that includes a device public key to a system, wherein the system validates the security certificate, encrypts an authentication challenge using the device public key, and transmits the authentication challenge to the industrial device. The industrial device generates a device private key using the physical unclonable function response and decrypts the authentication challenge using the device private key. The industrial device generates an authentication response based on the authentication challenge, encrypts the authentication response using the device private key, and transmits the authentication response to the system, wherein the system decrypts the authentication response using the device public key and authenticates the industrial device based on the authentication response.