Broadcast-Free Threshold Key Generation with PUFs for Quantum Security
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Solution Overview
Problem
Existing key generation protocols over unencrypted channels are vulnerable to quantum attacks and require encrypted communication, broadcast communication, or assumptions of honest parties, making them unsuitable for the quantum era and impractical for cold storage settings.
Innovation Solution
A broadcast-free, threshold post-quantum key generation and verification protocol using hardware-based correlated randomness, specifically through physically unclonable functions (PUFs) to generate learning parity with noise (LPN) instances, which are sent over unencrypted channels to a central combiner for key combination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If existing key generation protocols are used over unencrypted channels, then key generation can be performed without encrypted communication, but the protocols are vulnerable to quantum attacks
Solution Approach 1:
The patent changes the cryptographic parameters from classical symmetric/asymmetric encryption to post-quantum cryptographic primitives including lattice-based LPN problems, code-based schemes, and hash-based constructions. This parameter change enables security against quantum attacks while maintaining operation over unencrypted channels.
Solution Approach 2:
The patent replaces traditional cryptographic mechanisms (encrypted communication channels, broadcast protocols) with hardware-based correlated randomness from physically unclonable functions (PUFs). This substitution eliminates the need for trusted communication infrastructure while providing quantum-resistant security.
2Reliability
If encrypted communication channels with dedicated cryptographic commitment are used, then security against quantum attacks is improved, but device complexity and communication overhead increase
Solution Approach 1:
The patent extracts the security function from the communication channel layer and relocates it to the hardware randomness layer through PUFs. This extraction eliminates the need for encrypted channels while maintaining quantum security, as the PUFs provide correlated randomness directly at the hardware level.
Solution Approach 2:
The patent introduces physically unclonable functions (PUFs) as an intermediary between the communication channels and the key generation process. These PUFs serve as a trusted randomness source that enables secure key generation over unencrypted channels by providing hardware-based correlated randomness.
3Measurement precision
If broadcast communication with zero knowledge proofs is used, then verification of key correctness is improved, but communication overhead and computational complexity increase
Solution Approach 1:
The patent enables each device to self-verify its contribution to the key generation process using locally stored PUF responses and shared secrets. This self-service mechanism eliminates the need for complex broadcast zero-knowledge proofs while maintaining verification capability through distributed local computations.
Solution Approach 2:
The patent segments the verification process into individual local verification steps at each device rather than requiring centralized broadcast verification. Each device independently verifies its partial key contribution using its own PUF responses, distributing the verification workload and eliminating complex communication requirements.
4Measurement precision
If complete reliance on back and forth zero-knowledge proofs is used, then verification consistency is improved, but time for key generation increases
Solution Approach 1:
The patent performs preliminary action by pre-computing and storing PUF responses and verification data at each device before the actual key generation process. This preliminary preparation enables fast local verification without requiring time-consuming back-and-forth zero-knowledge proofs during key generation.
Solution Approach 2:
The patent enables devices to perform self-verification using pre-stored PUF responses and local computations, eliminating the need for lengthy interactive verification protocols. Each device can independently and quickly verify key consistency using its own hardware randomness characteristics.
Data Source
AI summary
Methods, systems, and apparatus for generating an encryption key. In one aspect, a method includes the generating and sending, by a first device, a stream of random challenges to other devices. Each other device processes, by a physically unclonable function (PUF) included in the device, the stream of random challenges twice to obtain pairs of responses and computes a first Bernoulli matrix vector. Each other device generates a first LPN instance using a pre-stored public matrix, a partial encryption key, and the first Bernoulli error matrix, and sends the first LPN instance to the first device. The first device computes a threshold number of the first LPN instances and an estimated combined error of PUFs included in the other devices. The first device generates an encryption key by recovering a summation of each partial encryption key encoded in the threshold number of first LPN instances.