Relay Attack Detection Using Phase and Time-of-Flight Comparison
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Solution Overview
Problem
Existing methods for detecting relay attacks, such as man-in-the-middle or phase manipulation attacks, require complex and expensive hardware, and existing distance measurement techniques using commercially available transceivers are frequency-dependent, leading to ambiguity and inefficiency.
Innovation Solution
A method that compares phase measurements and time-of-flight measurements on radio signals with overlapping frequency intervals, without converting to distances, to detect deviations indicative of a relay attack, using phase shift and signal propagation time changes relative to frequency changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex hardware methods are used for relay attack detection, then detection reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the parameter being measured from distance to frequency-dependent phase and propagation time characteristics. By measuring how phase and propagation time change with frequency rather than calculating absolute distances, the system detects relay attacks using standard transceiver components without requiring complex additional hardware, thus maintaining reliability while reducing device complexity
Solution Approach 2:
The patent replaces complex detection hardware with a software-based analysis of frequency-dependent signal characteristics. Instead of using specialized hardware to detect relay attacks, the system uses standard transceivers and processes the frequency-dependent phase and propagation time data through computational methods, substituting mechanical/hardware complexity with signal processing
2Measurement precision
If distance measurements are calculated from phase measurements, then measurement precision is improved, but ambiguity and processing complexity increase
Solution Approach 1:
The patent extracts and compares only the frequency-dependent characteristics of phase and propagation time measurements rather than calculating complete distance values. By taking out and analyzing specifically how these measurements change with frequency, the system avoids the ambiguity inherent in distance calculations while maintaining measurement precision for relay attack detection
Solution Approach 2:
Instead of converting phase measurements to distances (the conventional approach), the patent inverts the approach by directly comparing frequency-dependent phase and propagation time changes. This inversion avoids the distance calculation ambiguity problem while achieving the same detection goal with simpler processing
3Productivity
If single-frequency measurements are used, then measurement speed is improved, but detection reliability decreases due to frequency-dependent ambiguities
Solution Approach 1:
The patent uses periodic frequency variation to measure phase and propagation time at multiple frequencies. By systematically varying the frequency and measuring at each step, the system efficiently gathers the necessary data to detect frequency-dependent relay attack characteristics without requiring complex simultaneous multi-frequency measurements, thus maintaining measurement speed while improving reliability
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
Enables simple, fast, and reliable detection of relay attacks by comparing phase and propagation time measurements, reducing hardware complexity and ambiguity, and allowing for robust detection even in the presence of interference.
Implementation Method 1
the change in the phase measurements when the frequency changes or the change in the phase shifts when the frequency changes
Implementation Method 2
time-of-flight measurements (pulse time-of-flight measurements, ToF) can be carried out on these radio signals
Data Source
Figure 1~2
AI summary
The invention relates to a method for detecting and/or preventing relay attacks. The object is achieved by a method for detecting a relay attack, wherein radio signals at different frequencies are transmitted between a first and a second object and phase measurements and propagation time measurements are performed on these radio signals, and the change in the phase measurements for a change in the frequency is compared with the signal propagation measurements or their change, and, if a predetermined difference or a difference determined from measurements on the radio signals is exceeded, it is assumed that a relay attack is taking place.