Vehicle Access Authorization via Signal Time-of-Flight Measurement
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Solution Overview
Problem
Existing methods for determining access authorization in transportation vehicles, such as keyless-entry systems, are vulnerable to relay attacks and require complex designs or conversions, making them unsuitable for existing systems and lacking in precise distance determination.
Innovation Solution
A method where a transportation vehicle's internal authorization device generates a request signal upon a trigger event, calculates a time difference between the receipt of a response signal and a comparison response signal, and grants access only if the difference falls below a predefined threshold, ensuring secure and reliable access without the need for extensive system modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If keyless-entry systems are used for transportation vehicles, then ease of operation is improved, but vulnerability to relay attacks increases
Solution Approach 1:
The system performs preliminary distance determination by comparing the time of flight of signals before granting access authorization. The authorization device calculates the distance between the wireless key and vehicle based on signal transmission time, and only allows access if the key is within a predetermined distance threshold, preventing relay attacks before they can succeed
Solution Approach 2:
The patent replaces physical key verification with electromagnetic signal-based distance measurement. Instead of relying solely on cryptographic authentication of wireless signals, the system uses time-of-flight measurement of electromagnetic signals to physically determine the key's proximity to the vehicle, substituting mechanical distance verification with electronic signal timing
2Reliability
If distance determination methods are implemented to prevent relay attacks, then security is improved, but device complexity increases
Solution Approach 1:
The authorization device performs multiple functions using the same communication infrastructure: it authenticates the wireless key through cryptographic verification and simultaneously determines distance through time-of-flight measurement of the same signals. This multi-functionality approach avoids adding separate dedicated distance measurement hardware, reducing overall system complexity
Solution Approach 2:
The system uses the existing challenge-response communication signals between the vehicle and wireless key to carry distance measurement information. The same electromagnetic signals used for authentication inherently contain timing information that can be used for distance determination, eliminating the need for separate measurement signals or additional communication channels
3Reliability
If existing keyless access systems are modified to include distance determination, then security is improved, but ease of manufacture deteriorates
Solution Approach 1:
The system calculates distance using the time of flight of signals that are already being exchanged during the normal authentication process. By performing distance determination as a preliminary check before access authorization using existing authentication signals, the system avoids the need for separate conversion or modification of existing keyless access systems
Solution Approach 2:
The patent measures the time of flight of authentication signals with higher precision than traditionally required, using this excessive measurement capability to derive accurate distance information. This partial use of timing data from existing signals provides both authentication and distance determination functions without requiring complete system redesign
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 method effectively prevents relay attacks by accurately determining the distance between the vehicle and the wireless key, enhancing security and anti-theft protection while being compatible with existing keyless access systems without requiring significant changes or additional materials.
Implementation Method 1
the authorization device (14) determines a time difference between a time of receipt of the response signal and a time of receipt of the comparison response signal
Data Source
AI summary
A method for determining an access authorization to a transportation vehicle, wherein an internal authorization device emits a request signal into an environment of the transportation vehicle depending on a predefined triggering event. The authorization device checks the response signal received for at least one request condition. Based on the at least one request condition, access to the transportation vehicle is granted. Concurrently, the transportation vehicle-internal authorization device forwards the request signal to a transportation vehicle-internal key processing unit which calculates a comparison response signal and forwards the signal to the authorization device. The authorization device determines a time difference between a time of receipt of the response signal from the environment of the transportation vehicle and a time of receipt of the comparison response signal. The at least one request condition is satisfied in response to the calculated time difference being below a predetermined threshold value.