CAN Bus Traffic Confidentiality via Padding Bits
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Solution Overview
Problem
Existing bus-based communication systems, such as CAN, face challenges in providing real-time data security and authenticity, particularly in in-vehicle networks where malicious commands or protocol frames can be injected, compromising system integrity and safety.
Innovation Solution
The implementation of a transmitter and receiver device within the bus-based communication system that adds padding bits to the payload or frames at either the transport layer or data link layer to provide traffic flow confidentiality, ensuring that the true amount of data carried in a communication is hidden from observers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If padding bits are added to the payload or frames to provide traffic flow confidentiality, then data security and authenticity are improved, but communication protocol complexity and processing overhead increase
Solution Approach 1:
The communication protocol is segmented into distinct layers (physical layer, data link layer, transport layer) with padding bit insertion points defined at specific layers. This segmentation allows the confidentiality mechanism to be implemented without affecting other protocol functions, resolving the contradiction by isolating the security enhancement to specific protocol segments.
Solution Approach 2:
Padding bits are added preliminarily to the payload or frames before transmission, establishing traffic flow confidentiality in advance. This preliminary action ensures that the true data length is hidden from observers without requiring complex real-time processing, thus improving security while minimizing protocol complexity.
2Reliability
If padding bits are added to hide the true amount of data, then traffic flow confidentiality is improved, but communication efficiency and transmission time increase
Solution Approach 1:
The protocol allows dynamic adjustment of padding bit parameters (such as padding length and insertion position) to balance confidentiality requirements with communication efficiency. By changing these parameters based on specific application needs, the system can achieve adequate security without excessive overhead that would severely impact productivity.
Solution Approach 2:
Instead of padding to a fixed maximum length, the protocol applies partial padding only when necessary to achieve traffic flow confidentiality. This partial action approach provides sufficient security protection while minimizing the excessive data transmission overhead that would otherwise degrade communication efficiency.
3Reliability
If authentication tags are included in frames, then data authenticity is improved, but frame size and processing overhead increase
Solution Approach 1:
The authentication tag is nested within the existing frame structure at the transport layer, integrating the authenticity verification mechanism into the normal data flow without requiring separate transmission channels. This nesting approach provides data authenticity while minimizing the additional frame size overhead.
Solution Approach 2:
The authentication tag acts as an intermediary element that enables authenticity verification without requiring complex direct verification mechanisms. By introducing this intermediary authentication component, the system achieves reliable data authenticity with minimal impact on frame size and processing overhead.
Data Source
AI summary
A transmitter device of a bus-based communication system may add one or more padding bits, associated with providing traffic flow confidentiality for communication of a payload on a communication bus, either to the payload on a transport layer, or to one or more first frames on a data link layer. The one or more first frames may include a transport layer payload associated with the payload. The transmitter device may transmit one or more second frames, including a data link layer payload associated with the one or more first frames, on the communication bus. A receiver device of the bus-based communication system may receive the one or more second frames on the communication bus. The receiver device may process the one or more padding bits from either the one or more first frames on the data link layer, or from the payload on the transport layer.