Vehicle Clock Synchronization via Two-Phase Unencrypted and Encrypted Authentication

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Solution Overview

Problem

Existing methods for synchronizing clocks in vehicle control devices within distributed networks face challenges in being simple, quick, reliable, and secure, especially in systems with slow or unpredictable throughput times, which can lead to inadequate authentication and cybersecurity risks.

Innovation Solution

A two-phase method where unencrypted communication is used initially to determine the time difference between clocks, followed by encrypted authentication to ensure message integrity, allowing for quick and secure synchronization without interfering with the synchronization process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If individual authentication of messages is performed using slow and/or poorly predictable cryptography, then security is improved, but synchronization speed and computational efficiency deteriorate

Engineering Contradiction:
ImprovesecurityVSAvoidsynchronization speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent divides the authentication process into two distinct phases: Phase 1 performs unencrypted message exchange for time difference determination without individual message authentication, while Phase 2 performs encrypted authentication of the exchanged messages. This segmentation allows the time-critical synchronization to proceed quickly in Phase 1, while security is ensured in Phase 2, thus resolving the contradiction between security and synchronization speed.

Inventive Principle:
Principle #1Segmentation

2Reliability

If individual authentication of messages is performed using slow and/or poorly predictable cryptography, then security is improved, but computational effort increases

Engineering Contradiction:
ImprovesecurityVSAvoidcomputational effort
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent segments the communication process into Phase 1 (unencrypted, no authentication) and Phase 2 (encrypted authentication). By restricting cryptographic operations to Phase 2 and applying them only to the time difference determination messages rather than every synchronization message, the computational effort and energy consumption are significantly reduced while maintaining security.

Inventive Principle:
Principle #1Segmentation

3Reliability

If encrypted communication is used for all message exchanges, then security is improved, but synchronization speed and simplicity deteriorate

Engineering Contradiction:
ImprovesecurityVSAvoidsynchronization speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies different communication modes to different phases: Phase 1 uses unencrypted communication for fast time difference determination, while Phase 2 uses encrypted communication for secure authentication. This local differentiation of communication quality allows the system to optimize for speed where security is less critical (Phase 1) and for security where required (Phase 2), resolving the contradiction between security and synchronization speed.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4009683B1Method for synchronisation of clocks of at least two devices
Publication Date: 2023.09.06 VOLKSWAGEN AG
  • EP4009683B1 patent drawingFigure 1
  • EP4009683B1 patent drawingFigure 2

AI summary

1. A method for synchronizing the clocks of at least two devices (A, B) in a distributed network (N) of a vehicle (100), comprising the following steps: - Establishing unencrypted communication (K1) between the at least two devices (A, B) to determine a time difference (dt) between the clocks of the two devices (A, B), - Exchanging messages (ai, bi) between the at least two devices (A, B) via the unencrypted communication (K1), - Determining a time difference (dt) between the clocks of the at least two devices (A, B) using the messages (ai, bi), - Establishing encrypted communication (K2) between the at least two devices (A, B) to authenticate the exchange of messages (ai, bi), - Authenticating the messages (ai, bi) used to determine the time difference (dt), - Using the determined time difference (dt) when the authentication of exchanged messages (ai, bi)bi) was successfully completed.