In-Vehicle CAN Bus Security With Ephemeral Session Keys

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing in-vehicle bus communication systems lack robust security, particularly on Controller Area Network (CAN) buses, due to the use of long-term shared keys that are vulnerable to key leakage, compromising data transmission between low-speed and high-speed buses.

Innovation Solution

Implementing a secure communications method that negotiates ephemeral session keys using ephemeral public and secret keys, based on pre-shared keys, to enhance security through ephemeral session key agreements and application layer session authentication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If long-term shared keys are used for encryption on CAN bus, then data transmission security is provided, but key leakage risk increases and security is compromised

Engineering Contradiction:

Improvedata transmission securityVSAvoidkey leakage risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent transitions from static long-term shared keys to dynamic ephemeral session keys that are generated and updated continuously through key negotiation between communication parties. This dynamic key management eliminates key leakage risks associated with static keys while maintaining encryption security.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the key parameter from long-term persistent keys to short-lived ephemeral keys with different characteristics (shorter duration, frequent regeneration). This parameter change fundamentally alters the security model to prevent key leakage while maintaining cryptographic protection.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If ephemeral session keys are negotiated, then key leakage is prevented and security is improved, but communication complexity increases

Engineering Contradiction:

Improvekey leakage preventionVSAvoidcommunication complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The key negotiation process is self-executing between communication parties without requiring external key management infrastructure. Each party independently generates ephemeral keys and performs negotiation, eliminating the need for complex centralized key management systems while achieving key leakage prevention.

Inventive Principle:

Principle #25Self-service

3Reliability

If application layer session authentication is implemented, then communication security is enhanced, but processing overhead increases

Engineering Contradiction:

Improvecommunication securityVSAvoidprocessing overhead

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Authentication and key negotiation are performed preliminarily before actual data transmission begins. Once authenticated, the ephemeral session key is established and reused for subsequent communications, reducing processing overhead during actual data transfer while maintaining enhanced security.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12432185B2Secure communications method and apparatus

Publication Date: 2025.09.30 YINWANG INTELLIGENT TECHNOLOGIES CO LTD

AI summary

A secure communications method includes: receiving, by a first network device, a second ephemeral public key of a second network device; determining, by the first network device, an ephemeral session key based on a first shared key, a first ephemeral secret key of the first network device, and the second ephemeral public key, where the first shared key is shared between the first network device and the second network device; and performing, by the first network device, secure communication with the second network device based on the ephemeral session key.