Message Authentication via Propagation Time Difference Measurement
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Solution Overview
Problem
Existing communication systems, such as those using the CAN bus, lack safety measures to authenticate messages, making them vulnerable to intrusions that can compromise safety-critical functions in vehicles.
Innovation Solution
A method that determines the time difference between message reception points at two predefined positions on the communication medium and compares it to reference time differences to verify the authenticity of the message sender, using a processing unit and a time-to-digital converter to efficiently achieve this.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clock-based intrusion detection systems are used to detect anomalies in message transfer, then authentication capability is provided, but aperiodic messages cannot be evaluated and intruders can circumvent the system by adapting their transfers to match observed clock offsets
Solution Approach 1:
The patent changes the detection parameter from clock offsets to propagation time differences. By measuring the time difference between when a message is received at two different positions on the communication medium, the system creates a new parameter (propagation time difference) that is independent of message periodicity and resistant to intruder adaptation.
2Measurement precision
If voltage-based intrusion detection systems are used to analyze voltage signatures, then detection accuracy is improved, but voltage fluctuations due to temperature changes cause false positives and high resource requirements are necessary
Solution Approach 1:
The patent substitutes the voltage-based detection mechanism with a time-based detection mechanism. Instead of analyzing voltage signatures that are sensitive to temperature, the system measures propagation time differences, which are not affected by temperature fluctuations. This replacement eliminates the temperature sensitivity issue while maintaining detection accuracy.
3Reliability
If comprehensive analysis of voltage signals is performed to create voltage signature models, then authentication reliability is improved, but computing resource requirements increase significantly
Solution Approach 1:
The patent extracts only the essential information needed for authentication - the propagation time difference - from the complete voltage signal analysis. By focusing solely on timing information rather than comprehensive voltage signal analysis, the system achieves reliable authentication with significantly reduced computing resource requirements.
4Reliability
If existing authentication systems based on physical properties are used, then authentication is provided, but high computing resources are required and the systems are not robust against signal fluctuations
Solution Approach 1:
The patent uses a simple, inexpensive timing measurement approach rather than complex voltage analysis. The propagation time difference measurement is a simple temporal parameter that can be obtained with minimal computational overhead, making the authentication system both reliable and resource-efficient.
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 reliable authentication with low resource requirements, achieving high identification rates and a low false positive rate, thus enhancing the security of communication systems and meeting standards like Automotive Safety Integrity Level (ASIL).
Implementation Method 1
a time-to-digital converter to efficiently achieve this
Data Source
AI summary
A method for checking a message in a communication system, in which multiple users are connected to a communication medium and exchange messages via same. A time difference between points in time of reception of a message that is sent on the communication medium is ascertained at two different, predefined positions on the communication medium, and based on a comparison of the time to at least one reference time difference, it is determined whether the message originates from a verified user.