Vehicle Bus Message Authentication Using MAC and Secret Key
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle bus message authentication methods, such as checksums, do not effectively ensure the integrity of messages against intentional or unintentional corruption, and they consume valuable payload space, which can limit the communication of additional information.
Innovation Solution
The method involves storing multiple copies of a data message, with one copy being used to create a message authentication code (MAC) using a secret key and MAC algorithm, which is included in the serial bus message. The receiving ECU verifies the MAC using the same secret key and algorithm, allowing for the authentication and acceptance or rejection of the data message based on the comparison.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a checksum is used to verify message integrity, then unintentional corruption can be detected, but the method does not protect against intentional alteration and consumes payload space
Solution Approach 1:
The patent extracts the authentication function from the data payload by using a separate MAC field. The MAC is computed separately from the data message using a secret key, allowing the data payload to remain intact while providing independent authentication. This resolves the contradiction by separating the verification mechanism from the data content, ensuring integrity without consuming valuable payload space.
Solution Approach 2:
The patent introduces a MAC (message authentication code) as an intermediary element between the sender and receiver. This MAC serves as a mediator that provides authentication and integrity verification without requiring the transmission of additional data beyond what is already sent. The MAC acts as a cryptographic seal that verifies message authenticity without consuming payload space.
2Reliability
If a checksum is included in the serial bus message, then message corruption can be detected, but it consumes space that could be used for additional information
Solution Approach 1:
The patent changes the parameter of authentication from traditional checksums to cryptographic MACs. This parameter change transforms the verification mechanism from a simple error-detection code to a secure authentication code that provides both integrity verification and authentication. The MAC parameter allows for more efficient use of space while providing enhanced security and reliability for data transmission.
3Reliability
If multiple copies of data message are stored and used for MAC creation, then message authentication is strengthened, but memory usage increases
Solution Approach 1:
The patent applies preliminary action by storing multiple copies of the data message in memory before MAC generation. This ensures that the original data is preserved and can be used to create the MAC without modifying the stored copies. The preliminary storage of data copies enables robust authentication while maintaining data integrity, resolving the contradiction between enhanced security and memory usage.
Data Source
AI summary
A method of transmitting data within a vehicle includes: storing two copies of a data message; constructing at an electronic control unit (ECU) a serial bus message that includes one copy of the data message and a message authentication code (MAC) created using a secret key stored at the ECU, a MAC algorithm, and a different copy of the data message; transmitting the serial bus message to a receiving ECU over a vehicle bus; authenticating the serial bus message at the receiving ECU using a copy of the key stored at the receiving ECU by creating a copy of the MAC from the data message included in the serial bus message and the copy of the key; comparing the MAC from the serial bus message with the copy of the MAC created at the receiving ECU; and rejecting or accepting the data message based on the comparison.