Vehicle Terminal Session Key Generation for Platoon Latency Reduction

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Solution Overview

Problem

Current communication systems in vehicle platoons face challenges in reducing computational effort and data size for encryption, leading to increased latency and safety distance between vehicles, which affects fuel efficiency and drive energy utilization.

Innovation Solution

A vehicle-side terminal system that determines a symmetrical key independently and locally, using it to generate a session key for secure communication channels, reducing the need for certificate management and enhancing communication efficiency by changing session keys and identifiers synchronously.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If asymmetric encryption methods are used for secure communication between vehicles, then communication security is improved, but computational effort and data size increase, leading to increased latency

Engineering Contradiction:
Improvecommunication securityVSAvoidlatency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent segments the encryption system into two parts: asymmetric encryption for key exchange (security-critical) and symmetric encryption for data transmission (efficiency-critical). This segmentation allows each encryption type to be used where it is most effective, resolving the contradiction between security and latency.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary key exchange using asymmetric encryption before data transmission, establishing symmetric keys in advance. This preliminary action allows subsequent data transmission to use faster symmetric encryption, reducing overall latency while maintaining security.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If asymmetric encryption methods are used for secure communication between vehicles, then communication security is improved, but the size of encrypted data increases

Engineering Contradiction:
Improvecommunication securityVSAvoiddata size
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent segments the encryption system into two parts: asymmetric encryption for key exchange (security-critical) and symmetric encryption for data transmission (efficiency-critical). This segmentation allows each encryption type to be used where it is most effective, resolving the contradiction between security and data size.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses symmetric keys as copies that can be efficiently transmitted and reused for data encryption. Instead of using large asymmetric encryption for all data, symmetric keys serve as compact copies that enable efficient encryption/decryption of the actual data payload.

Inventive Principle:
Principle #26Copying

3Reliability

If session keys are changed frequently to improve security, then communication security is improved, but computational effort and identifier management complexity increase

Engineering Contradiction:
Improvecommunication securityVSAvoididentifier management
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the session key with the identifier used for addressing vehicles. This combination means that when the identifier changes, the session key automatically changes as well, simplifying management while maintaining security through frequent key changes.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent makes the identifier serve dual functions: both for addressing vehicles and for encryption/decryption. This multi-functionality reduces the number of separate components that need to be managed, simplifying the system while enabling frequent key changes for security.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3599738B1First vehicle side terminal, method for operating the first terminal, second vehicle side terminal and method for operating the second vehicle side terminal
Publication Date: 2023.09.06 ROBERT BOSCH GMBH
  • EP3599738B1 patent drawingFigure 1
  • EP3599738B1 patent drawingFigure 2
  • EP3599738B1 patent drawingFigure 3

AI summary

A method for operating a vehicle-side terminal (NNa) comprises: determining a symmetric key, randomly determining an input value, sending a first message comprising the symmetric key and the input value towards a second vehicle-side terminal, determining a session key depending on the symmetric key and depending on the input value, selecting the determined session key as the currently valid session key, receiving a second message comprising encrypted data from the second vehicle-side terminal, and determining unencrypted data depending on the encrypted data and the currently valid session key.