PUF Entropy Key Generation for Unpredictable Device Security
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing security systems face challenges in generating sufficient unpredictable security keys due to limitations in the number and quality of physically unclonable function (PUF) bits, making them vulnerable to physical and side-channel attacks, and costly to implement effectively.
Innovation Solution
A security system incorporating a physically unclonable function circuit that generates entropy bit strings, which are manipulated using an operation entropy bit string to produce a security key through various operations, enhancing key unpredictability and randomness, and utilizing a deterministic random bit generator to produce unlimited random numbers for cryptographic applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If more PUFs are used to generate more entropy bits, then security key quantity and quality improve, but cost and area increase
Solution Approach 1:
The patent divides the entropy generation process into multiple stages: initial entropy bit generation from PUFs, entropy pool accumulation, and deterministic random bit generation. This segmentation allows the system to use a small number of PUFs to seed a larger entropy generation mechanism, resolving the contradiction between security key quality and device area.
Solution Approach 2:
The patent performs preliminary entropy collection during an enrollment phase, storing entropy bits in an entropy pool before actual key generation is needed. This preliminary action allows the system to accumulate sufficient entropy from limited PUFs, which can then be expanded deterministically when needed, avoiding the need for large numbers of PUFs.
2Reliability
If PUF-based security keys are implemented, then protection against physical attacks improves, but vulnerability to side-channel attacks remains
Solution Approach 1:
The patent introduces an intermediary deterministic random bit generator that processes the raw PUF entropy. This intermediary layer transforms the physical PUF characteristics into cryptographic keys through deterministic algorithms, adding a layer of abstraction that protects against direct side-channel attacks on the PUF while maintaining protection against physical attacks.
3Reliability
If entropy bits are collected from PUFs, then key unpredictability improves, but the number of available bits is limited
Solution Approach 1:
The patent transitions from the physical dimension of PUF bits to the computational dimension of deterministic random bit generation. By using a deterministic random bit generator seeded with PUF entropy, the system expands the limited physical entropy into a much larger space of possible cryptographic keys, effectively moving from one dimension (physical bit count) to another (computational key space).
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A security system (100) with entropy bits includes a physically unclonable function circuit (110), and a security key generator (120). The physically unclonable function circuit (110) provides a plurality of entropy bit strings (S1 to S6). The security key generator (120) generates a security key (S1) by manipulating a manipulation bit string derived from the plurality of entropy bit strings (S1 to S6) according to an operation entropy bit string. Each bit of the operation entropy bit string is used to determine whether to perform a corresponding operation to the manipulation bit string.