Vehicle Passive Entry Relay Attack Prevention via RSSI Correlation
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Solution Overview
Problem
Passive entry systems in vehicles are susceptible to relay attacks, where thieves extend the communication range between the vehicle and the key fob, allowing unauthorized access or starting of the vehicle.
Innovation Solution
A passive entry system with a control module and multiple antennas that transmit signals with varying power levels, allowing the key fob to generate a measurement report on received signal strength, which the control module uses to authenticate the key fob's location and prevent relay attacks by ensuring the correct power correlation and location-based operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the communication range between the vehicle and key fob is extended to allow passive entry from a distance, then the ease of operation is improved, but the system becomes vulnerable to relay attacks where thieves can intercept and extend the communication range
Solution Approach 1:
The system transmits a predetermined number of signals with different power levels instead of a single signal. The key fob measures the received signal strength indicator (RSSI) for each signal and reports back. The vehicle controller verifies that the RSSI values correlate with the expected power levels, ensuring the key fob is at the correct location and not being relayed through intermediate devices.
Solution Approach 2:
The key fob generates a measurement report containing RSSI values for each received signal and transmits it back to the vehicle controller. This feedback mechanism allows the controller to verify the authenticity of the key fob's location by comparing the reported RSSI values against the known power levels of the transmitted signals, thereby detecting relay attacks.
2Reliability
If multiple signals with different power levels are transmitted to prevent relay attacks, then the security against relay attacks is improved, but the device complexity increases
Solution Approach 1:
The communication process is segmented into multiple signal transmissions with different power levels. Instead of using a single complex authentication protocol, the system divides the verification into multiple simpler signal exchanges, where each signal has a distinct power level that can be easily measured and verified by the key fob.
Data Source
AI summary
A passive entry system of a vehicle includes relay attack prevention. The passive entry system includes a control module in the vehicle, at least one antenna at the vehicle and a key fob. A predetermined number of signals are transmitted via the at least one antenna with each signal having a different power strength. The key fob is determines a power strength of each signal that the key fob receives and generates a measurement report to transmit to the control module. The control module is configured to determine whether the measurement report contains received signal strength indicators for at least half of the predetermined number of signals and whether the received signal strength indicator for each signal contained in the measurement report correlates to the power strength of that signal as transmitted by the at least one antenna.