PUF Authentication System with Dynamic Key Refresh
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Solution Overview
Problem
PUF-based systems face challenges with hardware aging, leading to increased errors over time, and are vulnerable to side-channel attacks, which compromise the reliability of authentication and key regeneration.
Innovation Solution
Implementing a PUF-enabled authentication system that internalizes challenge-response behavior to maintain shares of a private key, allowing for periodic refresh of sensitive values and enabling threshold cryptographic operations without storing or reconstructing the private key, thereby mitigating aging and side-channel attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PUF-based systems are used for authentication and key regeneration, then hardware root-of-trust and tamper detection are established, but hardware aging leads to increased errors over time
Solution Approach 1:
The system dynamically refreshes challenge-response pairs over time, transitioning from static PUF responses to dynamically updated authentication credentials. This allows the system to adapt to hardware aging by periodically regenerating authentication data before error rates become critical.
Solution Approach 2:
The system implements periodic refresh of challenge-response pairs at scheduled intervals. By periodically updating authentication credentials before the PUF error rate becomes too high, the system extends its operational lifespan while maintaining authentication reliability.
2Ease of operation
If PUF challenge-response pairs are stored externally, then authentication functionality is enabled, but systems become vulnerable to side-channel attacks
Solution Approach 1:
The system extracts and removes the vulnerable external storage component for challenge-response pairs. By eliminating the need to store CRP data externally and instead regenerating it dynamically within the secure hardware boundary, the system removes the attack surface for side-channel attacks while preserving authentication functionality.
Solution Approach 2:
The system introduces a trusted hardware intermediary (the PUF device itself) that generates and maintains challenge-response pairs internally without external storage. This intermediary approach allows authentication functionality while preventing external exploitation through side-channel attacks.
3Productivity
If private keys are stored in PUF-enabled devices, then cryptographic operations can be performed, but devices are vulnerable to tampering and substitution attacks
Solution Approach 1:
The system extracts the private key from storage and eliminates it entirely. By using PUF-based challenge-response authentication that never stores private keys, the system maintains cryptographic operation capability while removing the vulnerability to tampering and substitution attacks that target stored keys.
Solution Approach 2:
The PUF device serves itself by dynamically generating authentication credentials from its inherent physical characteristics. This self-service approach eliminates the need for external key management and storage, providing cryptographic functionality while inherently protecting against tampering through the unclonable nature of PUFs.
Data Source
AI summary
An authentication system and device including physical unclonable function (PUF) and threshold cryptography comprising: a PUF device having a PUF input and a PUF output and constructed to generate, in response to the input of a challenge, an output value characteristic to the PUF and the challenge; and a processor having a processor input that is connected to the PUF output, and having a processor output connected to the PUF input, the processor configured to: control the issuance of challenges to the PUF input via the processor output, receive output from the PUF output, combine multiple received PUF output values each corresponding to a share of a private key or secret, and perform threshold cryptographic operations. The system and device may be configured so that shares are refreshable, and may be configured to perform staggered share refreshing.