Vehicle Keyless Entry Security Against Relay Station Attacks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for securing keyless vehicle unlocking systems against relay station attacks are not sufficiently reliable, as they can be vulnerable to interference and range extension by attackers.
Innovation Solution
A method involving the comparison of ambient noise signals received by two devices using cross-correlation to verify the proximity of the radio key to the vehicle, ensuring that the vehicle is only unlocked when the correlation is strong and phase shift is small, indicating a safe distance, and remains locked otherwise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ambient noise signals are compared using cross-correlation to verify proximity, then security against relay station attacks is improved, but device complexity increases
Solution Approach 1:
The patent uses ambient noise signals as an intermediary to verify the proximity of the radio key to the vehicle. Instead of directly measuring distance or using complex cryptographic protocols, the system captures and compares ambient RF noise patterns that naturally exist in the environment. These noise patterns serve as a mediator that proves the key and vehicle are in close proximity without requiring additional hardware or complex algorithms.
Solution Approach 2:
The system utilizes naturally occurring ambient RF noise from the environment (broadcasts, wireless communications, etc.) rather than generating or transmitting additional test signals. The existing environmental noise is repurposed for security verification, eliminating the need for dedicated test signal generation hardware and reducing overall system complexity while maintaining security.
2Reliability
If the vehicle remains locked when correlation is weak or phase shift is large, then security is improved, but ease of operation deteriorates
Solution Approach 1:
The system continuously monitors the cross-correlation results and phase shift between ambient noise signals, providing real-time feedback on the proximity verification status. The vehicle locking state is dynamically adjusted based on this feedback - unlocked when correlation is strong and phase shift is small (indicating close proximity), and locked when correlation is weak or phase shift is large (indicating potential relay attack). This automatic feedback mechanism maintains security without requiring user intervention.
3Measurement precision
If ambient noise signals are used for proximity verification, then measurement precision is improved, but difficulty of detecting and measuring increases
Solution Approach 1:
The patent replaces direct physical measurement methods (such as measuring signal strength or time of flight) with an electromagnetic field-based approach. Instead of mechanically or electronically measuring distance, the system measures the similarity of ambient RF noise patterns received at the vehicle and the radio key. This substitution uses cross-correlation of electromagnetic signals to infer proximity, achieving high precision while avoiding complex measurement hardware.
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
This approach provides a more secure verification of the radio key's proximity, preventing relay station attacks by distinguishing between safe and unsafe situations based on ambient noise patterns, enhancing the reliability of the keyless entry system.
Implementation Method 1
the device installed in the vehicle is woken and sends, to the radio key, a radio signal at a first frequency
Implementation Method 2
the first relay station and sent thereby on the second (normally, but not necessarily, much higher) frequency to the second relay station, which converts it back into the original radio signal of the first frequency
Implementation Method 3
One of the two devices sends the ambient noise signal received by it to the other device, where the ambient noise signal is compared with the ambient noise signal received here
Data Source
AI summary
The disclosure relates to a method and an apparatus to secure a system for passive unlocking of a vehicle system, particularly a vehicle unlocking system, against relay station attacks. The system comprises a vehicle-based device that can send on a first radio frequency and receive on a second radio frequency, and a driver-based device that can receive on the first radio frequency and send on the second radio frequency. The vehicle-based device and/or the driver-based device are also able to receive on a radio frequency that the other device can receive. One of the two devices send at least one ambient noise signal sequence to the other device. The ambient noise signal sequences received by both are compared with one another with cross-correlation. A current situation is deemed safe if the cross-correlation is strong and a phase shift is small.