PUF Identification Key Generation with Time-Invariant Resistor Discrimination
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Solution Overview
Problem
Physically unclonable functions (PUFs) used for generating identification keys face challenges in maintaining time invariance due to environmental influences and aging, leading to potential errors in resistance value measurements, which affects the reliability of the generated keys.
Innovation Solution
An identification key generation apparatus that discriminates resistors based on threshold values to exclude those with expected time variance, using a first, second, and third threshold value to determine the reliability of resistance measurements and generate a stable identification key.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PUF-based identification key generation is implemented, then device uniqueness and security are improved, but time invariance and measurement reliability deteriorate due to environmental influences and aging
Solution Approach 1:
The patent divides the identification key generation into two independent parts: a stable PUF-based component for uniqueness and a removable resistor component for time-invariant discrimination. By segmenting the key generation process, the system maintains device uniqueness through PUF while achieving time invariance through the separate, stable resistor measurement, resolving the contradiction between reliability and stability.
Solution Approach 2:
The patent introduces an intermediary discriminator circuit that measures resistor values and compares them against stored reference values. This intermediary component acts as a mediator between the unstable PUF and the final identification key, filtering out time-variant elements and ensuring only stable, time-invariant characteristics contribute to the final key, thus resolving the reliability-stability contradiction.
2Measurement precision
If multiple threshold values are used to discriminate resistors, then measurement precision and key stability are improved, but device complexity increases
Solution Approach 1:
The patent applies partial action by using multiple threshold values only when necessary to discriminate ambiguous resistor measurements. The system starts with a single threshold and only introduces additional thresholds when measurement precision requires it, thereby achieving the needed discrimination accuracy while minimizing the increase in device complexity.
Solution Approach 2:
The patent changes the parameter of threshold values dynamically based on measurement needs. Instead of using a fixed complex multi-threshold system always, the system adjusts the number and values of thresholds based on the specific measurement context, achieving high precision when needed while keeping the overall system relatively simple through parameter adaptation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution increases the reliability of the identification key by excluding resistors with potential time invariance issues, ensuring the generated key remains invariant over time and reducing errors caused by environmental changes and aging.
Implementation Method 1
resistance value measurements, which affects the reliability of the generated keys
Implementation Method 2
environmental influences and aging, leading to potential errors in resistance value measurements
Data Source
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AI summary
Provided are an apparatus and a method for generating an identification key with improved reliability by: providing a plurality of resistances which are generated according to a random connection state between conductive layers of a semiconductor due to process variation of the semiconductor; discriminating a first group which has a resistance value greater than a first threshold value and less than a second threshold value among the plurality of resistances; and reading at least one resistance which does not belong to the first group out of the plurality of resistances and reading an identification key in the form of a digital value.