ECU Pairing via Backend-Mediated Session Keys
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Solution Overview
Problem
Electronic Control Units (ECUs) in modern automobiles face challenges in secure data communication due to limited computational power and memory, making existing cryptographic protocols unsuitable for protecting sensitive data exchanges, and are vulnerable to attacks such as man-in-the-middle and masquerading.
Innovation Solution
A secure pairing method involving ECUs that includes sending identification data, receiving session data from a server, generating session keys, and establishing secure communication using a master session key (MSK) and tokens, with validation by a trusted backend server to ensure authentication and integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If asymmetric key algorithms are used for authentication and key exchange, then security is improved, but computational power and memory requirements increase beyond ECU capabilities
Solution Approach 1:
A backend server is introduced as an intermediary to perform the computationally intensive asymmetric key operations. The ECU only needs to execute lightweight symmetric key operations (AES-GCM) for authentication and data protection, while the server handles the complex key exchange and certificate verification, thus resolving the contradiction between security requirements and ECU computational limitations
Solution Approach 2:
The cryptographic protocol is segmented into two parts: (1) asymmetric key operations performed by the server, and (2) symmetric key operations performed by the ECU. This segmentation allows each component to perform only the operations suitable for its computational capabilities, enabling secure communication without overwhelming the ECU's processing power
2Reliability
If asymmetric key algorithms are used for authentication and key exchange, then security is improved, but memory requirements increase beyond ECU capabilities
Solution Approach 1:
The backend server serves as an intermediary that stores and manages cryptographic certificates and keys in its own memory space. The ECU only needs to store minimal authentication data and session keys, avoiding the need for large memory capacity required by traditional asymmetric key storage in the ECU itself
3Reliability
If traditional cryptographic protocols are used, then security is improved, but communication overhead and processing time increase
Solution Approach 1:
Cryptographic credentials and authentication data are pre-configured in the ECU during manufacturing. The backend server also pre-issues digital certificates and establishes trust relationships beforehand. This preliminary setup eliminates the need for complex real-time key generation and exchange, reducing processing time while maintaining security
Solution Approach 2:
The patent changes the cryptographic parameters by using AES-GCM with specific key lengths and initialization vectors that are optimized for the ECU's capabilities. The protocol uses 128-bit or 256-bit AES keys with GCM mode for authenticated encryption, providing strong security with reduced computational overhead compared to traditional RSA or ECC implementations
Data Source
AI summary
Systems and methods relate to pairing a first electronic control unit (ECU) to a second ECU. First identification data of the first ECU is transmitted to the second ECU. Second identification data of the second ECU is received from the second ECU. After a request to pair, the first ECU receives session data from a server. The session data includes a session identifier (ID) to identify the pairing, a master session key (MSK), a first token, and security information of the second ECU. The first ECU derives session keys based on the MSK. The session ID and the first token's encryption first token are transmitted to the second ECU. The first ECU receives and decrypts encryption of a second token from the second ECU. Secure communication is established between the first ECU and the second ECU via the session keys after the first ECU validates the second token.