Sensor PUF Arrays Using Randomly Addressable Element Pairs
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Solution Overview
Problem
Existing sensor-based PUFs face limitations in entropy due to limited calibration table sizes and are susceptible to side-channel attacks, particularly in ring oscillator PUFs, which are slow and vulnerable to electromagnetic interference.
Innovation Solution
Utilizing arrays of individually addressable sensor elements, such as ferroelectric sensors, to generate challenges and responses by comparing pairs of sensor elements based on electrical properties, with additional electrical stimuli, and implementing real-time comparisons to enhance entropy and detect malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ring oscillator PUFs are used for authentication, then device authentication capability is improved, but the system becomes slow and vulnerable to electromagnetic side-channel attacks
Solution Approach 1:
The patent replaces the mechanical counting process of ring oscillator oscillations with an electrical property comparison approach. Instead of counting oscillations over time, the system compares electrical properties (such as resistance, capacitance, or conductance) of sensor elements directly, enabling much faster response generation while maintaining authentication reliability
Solution Approach 2:
The patent introduces electrical property measurements as an intermediary between the physical sensor variations and the authentication decision. By measuring and comparing electrical properties of sensor elements rather than directly using oscillator counts, the system achieves both speed and security, mitigating electromagnetic side-channel vulnerabilities
2Reliability
If calibration tables are used in sensor-based PUFs, then unique responses are generated, but entropy is limited due to finite table sizes
Solution Approach 1:
The patent segments the sensor array into individually addressable sensor elements, where each element can be independently challenged and measured. This segmentation allows the system to generate responses from combinations of individual element measurements rather than relying on a finite calibration table, significantly increasing the effective entropy and response space
Solution Approach 2:
The patent transitions from a one-dimensional calibration table approach to a multi-dimensional space by individually addressing and combining measurements from multiple sensor elements. This dimensional expansion creates a vastly larger response space, increasing entropy beyond the limitations of traditional calibration table sizes
3Reliability
If sensor elements are individually addressable and compared in real-time, then entropy and security are enhanced, but device complexity increases
Solution Approach 1:
The patent makes the sensor array multi-functional by enabling it to serve both as a sensing element and as a PUF source. The same individually addressable sensor elements used for their primary sensing function are also utilized for generating unique cryptographic responses, eliminating the need for separate PUF hardware and reducing overall device complexity
Solution Approach 2:
The patent merges the calibration process with the PUF response generation process. By using the electrical property measurements taken during normal sensor operation and calibration for both sensor characterization and PUF challenge-response generation, the system achieves high security and entropy without requiring additional complex infrastructure
Data Source
AI summary
An arrangement and methods of using a sensor as a PUF is described. The sensor includes individually addressable sub elements. The sensor's output signal is a function of the response of its individually addressable sub elements, but the individual responses of sub elements are used as a CRP generation mechanism. Responses from the pairs of individually addressable sensor elements over ranges of environmental inputs are a unique sensor fingerprint and may be used for authentication, encrypted communication and for hardware tracking, as well as for detection of bad portions of the sensor or error injection attacks.