PUF Key Generation Using MAC for Uniformity
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Solution Overview
Problem
Semiconductor chip manufacturers face challenges in securely injecting unique secret keys onto chips, maintaining security against hacking and reading, reducing production costs, and ensuring uniformity and reliability of physical unclonable function (PUF) values used for key generation and pseudo-random number generation.
Innovation Solution
An improved PUF architecture that generates unique secure keys using a message authentication code (MAC) based on inputs from PUF devices, which increases the Hamming distance between keys and improves uniformity, allowing for cost-effective and secure key injection without storing keys in non-volatile memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If secret keys are injected onto chips during manufacturing, then unique cryptographic identities are provided for each chip, but security vulnerabilities arise including potential hacking, reading, and lack of uniformity in PUF values
Solution Approach 1:
The patent extracts the secret key from physical storage on the chip by using PUF (Physical Unclonable Function) technology. Instead of storing keys in non-volatile memory, the system generates keys dynamically from unique physical characteristics of the chip itself, eliminating the need for traditional key storage infrastructure and reducing security vulnerabilities associated with stored keys
Solution Approach 2:
The patent introduces PUF as an intermediary mechanism between the chip's physical characteristics and cryptographic key generation. The PUF circuit converts unique manufacturing variations into deterministic but unpredictable key material, serving as a mediator that transforms physical imperfections into secure cryptographic secrets without requiring direct key injection or storage
2Reliability
If traditional key injection methods are used, then keys can be provided on chips, but production costs increase and security against hacking and reading remains vulnerable
Solution Approach 1:
The patent enables chips to self-generate their own unique cryptographic keys during manufacturing based on their inherent physical characteristics. Each chip automatically creates its own secret key material through PUF circuits that exploit natural manufacturing variations, eliminating the need for expensive external key injection equipment and processes while ensuring each chip has unique, secure credentials
Solution Approach 2:
The patent changes the fundamental parameter of key generation from external injection to internal self-generation. By shifting from a process-driven approach (injecting keys) to a property-driven approach (extracting keys from physical characteristics), the system reduces manufacturing complexity and cost while improving security, as the keys become intrinsic to the chip rather than externally imposed
3Reliability
If PUF values are used for key generation, then unique identifiers are created, but uniformity and reliability of PUF values across chips may be inconsistent
Solution Approach 1:
The patent implements feedback mechanisms through challenge-response protocols where the system verifies PUF output consistency across multiple measurements. By challenging the PUF circuit with identical inputs and verifying that the responses match within expected tolerances, the system ensures uniformity of PUF values across chips while accounting for natural manufacturing variations, allowing reliable key generation despite physical imperfections
Data Source
AI summary
A method implemented in a computing device includes: generating an initial key from key injection or based on a value provided by at least one physical unclonable function (PUF); generating an obfuscated key based on the initial key; and storing the obfuscated key in a non-volatile memory.