Dynamic Secret-Key Generation for CAN Bus Message Authentication
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Solution Overview
Problem
Existing CAN bus architectures lack a built-in authentication process to ensure message authenticity, and known asymmetric public key cryptography systems require secure transmission of keys and certificates, which is inefficient and vulnerable to security threats.
Innovation Solution
Implement a dynamic secret-key generation process using a time-stamp exchange round trip delay algorithm to independently generate secret keys at each network node, ensuring secure encryption and decryption without transmitting keys, and dynamically changing the keys to thwart hacking attempts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If asymmetric public key cryptography systems are used for message authentication, then authentication capability is provided, but secure transmission of keys and certificates is required which increases system complexity and vulnerability
Solution Approach 1:
The patent extracts the secret key generation process from the traditional key transmission model. Instead of transmitting keys and certificates between devices, each device independently generates identical secret keys locally using a shared seed value and a deterministic algorithm. This eliminates the need for secure key transmission infrastructure and reduces system complexity while maintaining authentication reliability.
Solution Approach 2:
Each device performs self-service by independently generating its own secret key using the shared seed and the deterministic key derivation function. The devices do not rely on external key distribution services or certificate authorities, thereby simplifying the system architecture and reducing vulnerability to key transmission attacks while ensuring message authentication.
2Ease of operation
If static secret keys are used for encryption, then encryption simplicity is maintained, but security vulnerability increases due to potential key exposure
Solution Approach 1:
The patent implements dynamic secret keys that change over time by deriving keys from a shared seed using deterministic algorithms that can generate different key values at different times or for different communication sessions. This maintains encryption simplicity through deterministic generation while significantly reducing key exposure risk through key rotation and time-limited validity.
Solution Approach 2:
The system changes the parameter of the secret key from static to dynamic by using a deterministic key derivation function that takes the shared seed and additional variables (such as time stamps or session identifiers) to generate different key values. This allows the encryption mechanism to remain simple while the key material dynamically adapts to reduce exposure risk.
3Reliability
If frequent key changes are implemented to prevent hacking, then security against attacks is improved, but key management complexity increases
Solution Approach 1:
Each device independently manages its own key generation and rotation using the shared seed and deterministic algorithms. The devices automatically generate new keys when needed without requiring centralized key management infrastructure or complex coordination protocols, thereby achieving frequent key changes while keeping key management simple and decentralized.
Solution Approach 2:
The shared seed serves multiple functions: it is used to generate initial secret keys, to derive rotated keys for different sessions, and to ensure synchronization between devices. This multi-functionality reduces key management complexity by consolidating what would otherwise require multiple separate key distribution and management mechanisms into a single universal seed value.
Data Source
AI summary
A communications network includes a bus communicatively coupled to a first device and a second device. The first device and the second device are operable to perform multiple iterations of a secret-key generation (SKG) process. Each of the multiple iterations of the SKG process includes the first device computing a first instance of a key seed; the second device computing a second instance of the key seed; the first device using the first instance of the key seed to generate a first instance of a secret key; and the second device using the second instance of the key seed to generate a second instance of the secret key.