Dynamic Identifier Sequence for Vehicle Bus Masquerade Detection
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Solution Overview
Problem
Existing communication systems in vehicles face challenges in detecting and preventing masquerade errors, which occur when a message from a non-secure participant is misidentified as coming from a secure participant, especially when using a limited number of identifiers, such as with the CRC-8 checksum, which restricts the detection of erroneously routed messages beyond 255 transmitter/receiver paths without increasing bus bandwidth.
Innovation Solution
Implementing a dynamic identifier sequence based on a message counter, allowing each transmitter to use a changing identifier sequence, thereby extending the identifier space without additional bus load, and ensuring compatibility with safety standards like IEC 61508 and ISO 26262, by using the same CRC-8 checksum and message layout, and ensuring backward compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a CRC-8 checksum with static identifiers is used for masquerade detection, then the detection capability is limited to 255 transmitter/receiver paths, but increasing the identifier space would require additional bus bandwidth
Solution Approach 1:
The patent applies dynamics by transitioning from static identifiers to dynamic identifier sequences that change over time based on a message counter. Each transmitter uses a sequence of identifiers that evolves with each message transmission, allowing the system to distinguish between more transmitters without adding bandwidth. The identifier sequence is selected from a predefined set and changes dynamically, enabling extended masquerade detection capability while maintaining the same bus bandwidth requirements.
2Adaptability or versatility
If the identifier space is extended to support more transmitter/receiver paths, then more paths can be protected against masquerade, but the message layout and protocol complexity increase
Solution Approach 1:
The patent applies segmentation by dividing the identifier into two parts: a static base identifier and a dynamic sequence number. The base identifier remains the same in the message layout, while the sequence number is appended to form the full dynamic identifier sequence. This segmentation allows the system to support more communication paths without changing the fundamental message layout structure, thereby maintaining protocol simplicity while increasing versatility.
Solution Approach 2:
The patent applies dimensionality change by adding a temporal dimension to the identifier through the message counter. Instead of expanding the identifier space horizontally (which would require more bandwidth), the system expands vertically by using the time dimension - each message uses a different identifier from the sequence based on its position in the communication stream. This allows extended path identification without increasing the identifier width.
3Reliability
If a dynamic identifier sequence is implemented, then more transmitter/receiver paths can be distinguished, but the complexity of identifier management increases
Solution Approach 1:
The patent applies preliminary action by pre-defining identifier sequences for each transmitter before communication begins. Each transmitter is assigned a specific sequence of identifiers in advance, and the receiver stores these sequences in a lookup table. During communication, the transmitter simply follows its pre-assigned sequence, and the receiver matches the current identifier against the expected sequence. This preliminary configuration eliminates the need for complex real-time identifier generation and management, reducing operational complexity while maintaining high differentiation capability.
Data Source
Figure 1
AI summary
The invention relates to a method for transmitting a message between a transmitter and a receiver on a bus using an identifier associated with the transmitter/receiver path for the purpose of authentication and a message counter. The identifier is dynamically selected from an identification sequence depending on the message counter value and is integrated into the message check sum but not transmitted via the bus. The invention further relates to a control device and to a vehicle which are adapted to carry out the method for transmitting a message.