CAN Bus Forward Secrecy Key Generation via Pre-computation
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Solution Overview
Problem
Existing methods for secure communication over CAN bus, which uses an insecure shared communication medium, are inefficient in implementing forward secrecy for cryptographic keys, consuming significant time and network capacity when frequently generating new keys.
Innovation Solution
A method involving a controller and transceiver in nodes using a cryptographically secure pseudo-random number generator and one-way functions to generate and update shared secret cryptographic keys, ensuring forward secrecy by replacing older keys with new ones, while maintaining secure communication through the CAN bus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nodes frequently generate new cryptographic keys through simultaneous transmission on CAN bus, then forward secrecy is improved, but time consumption and network capacity usage increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-generating and storing multiple cryptographic key pairs in secure memory before they are needed. When key updates are required, nodes simply retrieve pre-generated keys from memory rather than performing time-consuming simultaneous transmissions and key agreement protocols, thus maintaining forward secrecy while dramatically reducing key generation time.
Solution Approach 2:
The patent implements periodic action by establishing predetermined triggers for key updates based on time intervals, message counts, or security events. This allows the system to maintain forward secrecy by periodically refreshing keys without requiring continuous or frequent key generation operations, thereby reducing overall time consumption and network capacity usage while preserving security properties.
2Reliability
If nodes frequently generate new cryptographic keys through simultaneous transmission, then forward secrecy is improved, but network capacity is consumed excessively
Solution Approach 1:
By pre-generating and storing multiple cryptographic key pairs in secure memory before they are needed, the system eliminates the need for frequent simultaneous transmissions on the CAN bus. This preliminary preparation maintains forward secrecy while dramatically reducing network capacity consumption, as key retrieval from memory requires no network communication.
Solution Approach 2:
The patent applies self-service by enabling nodes to autonomously retrieve and use pre-generated keys from their own secure memory without requiring interaction with other nodes or network communication for key generation. This self-contained approach maintains forward secrecy while eliminating network capacity consumption associated with traditional key agreement protocols.
3Reliability
If traditional key agreement methods are used on shared communication medium, then secure key exchange is achieved, but efficiency and speed of key generation deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-generating and securely storing multiple cryptographic key pairs in memory before they are needed for communication. When key updates are required, nodes simply retrieve pre-generated keys from memory rather than performing time-consuming simultaneous transmissions and key agreement protocols, thus maintaining security while dramatically improving key generation speed.
Data Source
AI summary
A method for shared secret agreement with forward secrecy includes generating a first plurality of bits of data using a cryptographically secure pseudo-random number generator applied to a node seed value and at least one index value, transmitting the first plurality of bits of data through a shared communication medium simultaneously to transmission of a second plurality of bits of data from a second node, identifying shared secret data with the second node using a portion of the first plurality of bits of data that are logical complements of the second plurality of bits of data, generating a shared seed value using a cryptographically secure one-way function applied to the shared secret data, and generating an updated node seed value using the cryptographically secure one-way function applied to the node seed value to replace the node seed value.