PUF Cryptoprocessor Key Exchange for Tamper-Resistant Security

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Solution Overview

Problem

Existing cryptographic methods are vulnerable to attacks on communicating endpoints, making it easier for attackers to compromise the security of devices like computers and smartphones.

Innovation Solution

Implementing a cryptoprocessor with physical unclonable function (PUF) circuitry to derive a response to challenges, using this response as an encryption key to encrypt a second encryption key, and providing it to the challenging party, thereby enhancing security without the need for additional cryptographic hardware.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional cryptographic hardware is used to secure communication endpoints, then security against attacks is improved, but device complexity and hardware requirements increase

Engineering Contradiction:
ImprovesecurityVSAvoidhardware requirements
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the PUF circuitry directly into the cryptoprocessor chip, merging the security function into the existing hardware rather than using separate cryptographic devices. This integration reduces overall system complexity while maintaining security benefits.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The PUF circuitry automatically generates unique cryptographic responses based on physical variations in the chip itself, without requiring external key management infrastructure. The chip serves its own security needs through its inherent physical characteristics.

Inventive Principle:
Principle #25Self-service

2Ease of operation

If cryptographic keys are stored in traditional hardware, then encryption operations can be performed, but vulnerability to physical tampering and attacks increases

Engineering Contradiction:
Improveencryption capabilityVSAvoidphysical tampering vulnerability
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The PUF exploits asymmetric physical characteristics of the chip - the exact same physical variations that make each chip unique also make reverse-engineering and cloning extremely difficult. The cryptographic response is derived from physical properties that cannot be replicated.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent converts the harmful effect of physical variations during manufacturing into a beneficial security feature. These same variations that could be seen as defects or inconsistencies are precisely what create the unclonable cryptographic identity of each chip.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If PUF circuitry is integrated into the cryptoprocessor, then security against physical attacks is enhanced, but manufacturing precision requirements increase

Engineering Contradiction:
Improvephysical attack resistanceVSAvoidchip fabrication consistency
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the approach from requiring precise control of physical parameters to exploiting natural variations in those parameters. Instead of trying to manufacture identical chips, the system is designed to work with and derive security from the inherent parameter variations.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3867785B1Secure cryptoprocessor
Publication Date: 2026.02.11 NOKIA SOLUTIONS & NETWORKS OY
  • EP3867785B1 patent drawingFigure 1
  • EP3867785B1 patent drawingFigure 2
  • EP3867785B1 patent drawingFigure 3

AI summary

According to an example aspect of the present invention, there is provided a cryptoprocessor comprising physical unclonable function circuitry comprising at least one physical unclonable function, and at least one processing core configured to process a challenge received from outside the cryptoprocessor by at least deriving a response to the challenge by providing the challenge as input to the physical unclonable function circuitry, using the response as an encryption key to encrypt a second encryption key, and by causing the encrypted second encryption key to be provided to a party which issued the challenge.