Transponder Security via Coupling Factor Measurement
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Solution Overview
Problem
Existing methods for protecting near field communication between an electromagnetic transponder and a terminal are inefficient in preventing pirate devices from simulating a terminal and establishing communication, as they require established communication to function and lack effective prevention mechanisms.
Innovation Solution
A method that calculates and compares the current coupling factor ratio between the transponder and the terminal, allowing acknowledgement only when in mechanical or quasi-mechanical contact, by adjusting the resistive load to ensure optimal coupling and prevent unauthorized communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If encryption systems are used to protect communication, then communication security is improved, but the system cannot detect pirate devices before communication is established
Solution Approach 1:
The patent measures the coupling factor before establishing communication to detect pirate devices in advance. By performing this measurement during the initial approach phase, the system can identify unauthorized devices before they can establish encrypted communication, thus preventing security breaches rather than just protecting during communication.
Solution Approach 2:
The patent divides the authentication process into separate phases: first measuring the coupling factor to detect pirate devices, then establishing encrypted communication if the measurement is valid. This segmentation allows the detection function to operate independently before communication begins, addressing the limitation that encryption alone cannot detect pirates.
2Ease of operation
If the transponder allows communication at any distance, then ease of operation is improved, but security against unauthorized communication deteriorates
Solution Approach 1:
The patent changes the parameter of coupling factor measurement to determine operational eligibility. By measuring whether the coupling factor indicates close proximity (suggesting legitimate use) versus distant proximity (suggesting potential piracy), the system dynamically controls access based on this physical parameter rather than allowing unrestricted communication.
3Reliability
If the system requires coupling factor measurement and comparison, then detection of pirate terminals is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback by comparing the measured coupling factor against expected values for legitimate versus pirate devices. This feedback mechanism allows the system to automatically determine whether to permit or block communication based on the measurement results, providing reliable pirate detection through a systematic comparison process.
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
Effectively prevents unauthorized communication by ensuring the transponder is in close proximity to the terminal, enhancing security without modifying the terminal and maintaining compatibility with existing encryption processes.
Implementation Method 1
a current value of a ratio of the current coupling factor between the transponder and the terminal to an optimum coupling factor with a first value of the resistive load is calculated
Data Source
AI summary
A method for protecting communication between an electromagnetic transponder and a terminal, wherein the transmission of an acknowledgement for a request received from a terminal by the transponder is only allowed when the transponder is in mechanical contact or in quasi-mechanical contact with the terminal.