PUF Wallet Key Derivation for Secure Blockchain Signing
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Solution Overview
Problem
Existing PUF technologies face challenges in balancing practicality, cost-efficiency, and security, particularly in integrating strong PUFs with standard semiconductor components, and are vulnerable to attacks such as man-in-the-middle and modeling attacks.
Innovation Solution
The introduction of an expanded PUF (ePUF) framework that combines a weak PUF with a cryptographic hash function to expand the challenge-response space, creating a hybrid PUF device with a large and unpredictable CRP space, while maintaining practicality and security through controlled access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a weak PUF is used, then the device is practical and cost-efficient, but the challenge-response space is limited making it vulnerable to attacks
Solution Approach 1:
The patent combines a weak PUF with a cryptographic hash function to create an expanded PUF (ePUF). The weak PUF provides the physical unclonability and practical implementation advantages, while the hash function expands the challenge-response space. This merging allows the system to achieve strong PUF security properties without the hardware complexity of implementing a strong PUF from scratch.
Solution Approach 2:
The cryptographic hash function acts as an intermediary that transforms the limited output of a weak PUF into a large challenge-response space. The hash function takes the weak PUF's response and expands it into multiple derived keys and challenge-response pairs, effectively mediating between the weak PUF's limitations and the security requirements of strong PUFs.
2Reliability
If a strong PUF is used, then the challenge-response space is large providing security, but integrating with standard semiconductor components becomes difficult
Solution Approach 1:
The patent merges a weak PUF (which is easy to integrate with standard semiconductor components) with a cryptographic hash function to achieve the security properties of a strong PUF. This combination allows the system to benefit from the manufacturing ease of weak PUFs while obtaining the large challenge-response space of strong PUFs through the hash function's expansion capability.
3Adaptability or versatility
If a weak PUF is used, then the hardware overhead is low, but the interface is restricted to only one or limited number of trusted parties
Solution Approach 1:
The patent combines a weak PUF with a cryptographic hash function to create an ePUF that can serve multiple parties. The hash function enables the generation of multiple derived keys from a single weak PUF instance, allowing the system to provide secure access to multiple trusted parties without requiring multiple separate weak PUFs, thus maintaining low hardware overhead while improving adaptability.
Solution Approach 2:
The expanded PUF structure enables a single weak PUF to serve multiple functions and multiple trusted parties. Through the hash function, the system can generate multiple challenge-response pairs and derived keys, making the PUF universally accessible to multiple parties while maintaining the low hardware overhead of a single weak PUF device.
Data Source
AI summary
A challenge is input to a PUF device comprising a physically unclonable function, PUF. The device generates a corresponding response. A wallet application is instantiated to use a seed determined from the response, the instantiating comprising storing a transform of the seed or response in association with the wallet application. At a later time, a user supplies the wallet application with information demonstrating a right to use the seed, wherein the wallet application is configured so as in response to verify this information based on the transform as stored in association with the wallet application, and on condition that the information is thereby verified, to derive at least one child key from the seed. A blockchain transaction is then signed using the child key as derived by the wallet application in response to the verification.