Sensor PUF Authentication via Calibration Data Extraction
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Solution Overview
Problem
Sensor-based systems connected to the web are vulnerable to cyber-attacks due to their susceptibility to manufacturing variations, which existing technologies have not adequately addressed in terms of cybersecurity.
Innovation Solution
The use of physically unclonable functions (PUFs) generated from sensor calibration tables and differential sensor systems to create unique cryptographic challenges and responses, enhancing authentication and security by leveraging natural manufacturing variations, and incorporating secure servers and SRAM-based PUFs to obscure and secure the authentication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensor calibration tables are used to generate PUF challenges and responses, then authentication security is improved, but device complexity increases
Solution Approach 1:
The patent extracts calibration data from sensor calibration tables to generate PUF challenges and responses. By taking out and utilizing existing calibration data that would otherwise be unused, the system creates unique cryptographic identifiers without adding significant hardware complexity. The calibration table, already present for sensor accuracy, serves dual purposes: sensor calibration and PUF authentication.
Solution Approach 2:
The calibration table serves multiple functions: it calibrates sensor readings for accuracy and simultaneously generates PUF challenges and responses for authentication. This multi-functionality reduces the need for separate authentication hardware, as the existing calibration infrastructure is leveraged for security purposes as well.
2Reliability
If differential sensor systems are implemented for PUF authentication, then security against cyber-attacks is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses differential sensor systems where two sensors are intentionally made slightly different through manufacturing variations. These asymmetric differences are not defects but are harnessed to create unique PUF responses. The system accepts and utilizes the natural manufacturing asymmetries rather than requiring perfect matching, turning a potential problem into a security feature.
Solution Approach 2:
Manufacturing variations that traditionally cause sensor mismatch problems are converted into beneficial unique identifiers for authentication. The natural imperfections in sensor fabrication, which would normally require complex calibration and matching procedures, are instead utilized to create unclonable cryptographic signatures that enhance security.
3Reliability
If PUF authentication mechanisms are added to sensor systems, then protection against cyber-attacks is improved, but ease of operation decreases
Solution Approach 1:
The sensor system automatically generates PUF responses using its own calibration data and sensor readings without requiring external authentication hardware or complex user interaction. The system self-authenticates by comparing its generated responses against stored challenges, making the authentication process transparent and automatic from the user perspective.
Solution Approach 2:
PUF challenges are pre-computed and stored in the system during manufacturing or initialization. When authentication is needed, the system simply retrieves the pre-prepared challenges and generates responses using current sensor readings, avoiding the need for complex real-time computation during the authentication moment itself.
Data Source
AI summary
Several methods may be used to exploit the natural physical variations of sensors, to generate cryptographic physically unclonable functions (PUF) that may strengthen the cybersecurity of microelectronic systems. One method comprises extracting a stream of bits from the calibration table of each sensor to generate reference patterns, called PUF challenges, which can be stored in secure servers. The authentication of the sensor is positive when the data streams that are generated on demand, called PUF responses, match the challenges. To prevent a malicious party from generating responses, instructions may be added as part of the PUF challenges to define which parts of the calibration tables are to be used for response generation. Another method is based on differential sensors, one of them having the calibration module disconnected. The response to a physical or chemical signal of such a sensor may then be used to authenticate a specific pair of sensors.