Vehicle On-Board Network Key Management via HSM Segmentation
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Solution Overview
Problem
Current vehicle on-board communication networks face challenges in rapidly and efficiently executing cryptographic operations due to reliance on symmetrical cryptography, which can lead to latency issues and potential vehicle instabilities, and asymmetrical cryptography cannot adequately secure keys outside the security module.
Innovation Solution
A method involving the generation and use of cryptographic keys during vehicle power supply initialization, where keys are transferred and used for a limited duration via cryptographic algorithms, combined with key derivation functions and storage in security modules, enabling secure and efficient communication between electronic control units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If symmetrical cryptography is used for rapid cryptographic operations, then execution speed is improved, but security is worsened because keys cannot be secured by hardware measures when available to host cores
Solution Approach 1:
The cryptographic key management is segmented into two distinct parts: asymmetrical cryptography is used for secure key distribution and establishment, while symmetrical cryptography is used for rapid data encryption. The cryptographic key is segmented into a long-term key stored securely in HSM and session keys derived for temporary use, separating the security-critical key storage from the speed-critical encryption operations.
Solution Approach 2:
A session key acts as an intermediary between the secure long-term key stored in HSM and the rapid symmetrical encryption operations. The session key is derived from the long-term key through a key derivation function, allowing secure communication without exposing the long-term key to host cores or requiring its direct use in fast encryption operations.
2Reliability
If asymmetrical cryptography is used for secure key distribution, then security is improved, but execution time is worsened due to long run-time
Solution Approach 1:
The long-term asymmetrical cryptographic key is established and stored securely in the HSM during device initialization or manufacturing, before any communication occurs. This preliminary setup allows subsequent symmetrical encryption operations to proceed rapidly using derived session keys, without repeated asymmetrical key exchange overhead.
Solution Approach 2:
Session keys are periodically derived from the long-term key for each communication session or time period, allowing the system to reuse the secure asymmetrical key infrastructure while enabling rapid symmetrical encryption for each periodic communication phase.
3Reliability
If cryptographic keys are stored in security module for security, then key protection is improved, but access speed is worsened when host cores need direct key access
Solution Approach 1:
A session key derived from the long-term key serves as an intermediary that allows host cores to perform rapid symmetrical encryption without direct access to or exposure of the long-term key stored in HSM. The session key can be temporarily made available to host cores for fast encryption operations while the long-term key remains protected in the security module.
Solution Approach 2:
The cryptographic system changes parameters by using different key types for different purposes: the long-term key with high security requirements remains in HSM, while session keys with lower security requirements but higher speed requirements are derived and used for actual encryption operations on host cores.
Data Source
AI summary
A method for using cryptographic keys in a vehicle on-board communication network. The method includes, during an initialization of a vehicle-bound power supply time period of a vehicle: generating at least one cryptographic key by a central electronic control unit for the respectively initialized vehicle-bound power supply time period of the vehicle; transferring the generated at least one cryptographic key by the central electronic control unit using at least one cryptographic algorithm to at least one further electronic control unit in the on-board communication network; using the transferred cryptographic key by at least one electronic control unit for at least one further or for the same cryptographic algorithm for a communication between the electronic control units for the duration of the respective initialized vehicle-bound power supply time period in the on-board communication network.