Electronic Key Motion Detection Relay Attack Prevention
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Solution Overview
Problem
Existing electronic key systems are vulnerable to relay attacks, where unauthorized individuals can unlock and start vehicles by relaying signals over long distances, as they do not reliably detect the motion of the key, leading to security risks.
Innovation Solution
An electronic key system equipped with a motion sensor and a microcontroller that performs multiple reference measurements to distinguish between short vibrations and longer movements, ensuring accurate detection of key motion and reducing power consumption by switching to low power mode when not in use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple motion detection is used, then device complexity is reduced, but measurement precision deteriorates leading to unreliable motion detection
Solution Approach 1:
The system performs preliminary reference measurements to establish baseline values before actual motion detection. Multiple reference measurements are taken and averaged to create a reliable reference state, which is then used to accurately detect subsequent motion events. This preliminary action ensures that the motion detection threshold is based on actual device characteristics rather than fixed assumptions.
Solution Approach 2:
The system performs multiple reference measurements (excessive measurements) beyond a single measurement to establish the reference state. By taking several measurements and averaging them, the system over-compensates for potential noise or anomalies in individual measurements, thereby achieving more reliable and precise motion detection thresholds.
2Reliability
If continuous motion monitoring is performed, then security is improved, but energy consumption increases
Solution Approach 1:
Instead of continuous monitoring, the system uses periodic motion detection triggered by specific events (e.g., when the key is detected near the vehicle or when authentication is attempted). Motion measurements are taken at these periodic intervals rather than continuously, reducing energy consumption while maintaining security reliability at critical moments.
Solution Approach 2:
The motion sensor system serves itself by using motion detection events to trigger authentication sequences. When motion is detected, the system automatically initiates the authentication process without requiring additional continuous monitoring or external intervention, efficiently utilizing the motion detection capability to drive the security protocol.
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
Enhances security by reliably authenticating the key's motion, preventing unauthorized access and reducing battery consumption, thereby protecting against relay attacks and improving system reliability.
Implementation Method 1
a motion sensor configured to detect a movement of the transponder unit
Data Source
AI summary
Upon a triggering event, an electronic key for a vehicle, comprising a microcontroller and a motion sensor to detect movement of a transponder unit, performs a first measurement resulting in a first measurement value, and compares the first measurement value to a predefined threshold value. Subsequently, the key: performs a plurality of first reference measurements to determine a first average value over the plurality of first reference measurements if the first measurement value is below the predefined threshold value; and performs a plurality of second reference measurements to determines a second average value over the plurality of second reference measurements, and compares the second average value with the first average value if the first measurement value equals or is above the predefined threshold value. The electronic key is considered as moving if a difference between the second average value and the first average value is greater than a third threshold.