Electronic Key Motion Sensor Relay Attack Prevention

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Solution Overview

Problem

Existing electronic key systems are vulnerable to relay attacks, which allow unauthorized access and starting of vehicles even when the key is not in proximity, due to signal relaying over long distances, compromising security without reducing user comfort.

Innovation Solution

An electronic key equipped with a motion sensor and processing unit that disables the transceiver when not moving and outside the vehicle, and keeps it enabled when inside, ensuring secure communication by confirming the key's location before disabling, thus preventing relay attacks and maintaining user convenience.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the transceiver is disabled when no motion is detected to prevent relay attacks, then security is improved, but user comfort deteriorates when the key is accidentally left inside the vehicle

Engineering Contradiction:
ImprovesecurityVSAvoiduser comfort
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system applies different transceiver states to different spatial locations: when the key is detected inside the vehicle, the transceiver remains enabled regardless of motion status; when outside the vehicle, the transceiver is disabled if no motion is detected. This location-based differentiation resolves the contradiction by allowing security measures only where appropriate.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The motion sensor acts as an intermediary that provides motion status information to the processing unit, which then determines the appropriate transceiver state. This intermediary mechanism enables the system to distinguish between intentional leaving (no motion inside) and accidental leaving (no motion detected after being inside), resolving the security-comfort contradiction.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the transceiver remains enabled to maintain user comfort, then ease of operation is improved, but security deteriorates due to vulnerability to relay attacks

Engineering Contradiction:
Improveuser comfortVSAvoidsecurity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The transceiver state is made dynamic rather than static, changing based on real-time conditions (location and motion status). The system transitions between enabled and disabled states according to the key's location and motion detection, allowing security measures to be applied only when and where necessary, thus maintaining comfort while improving security.

Inventive Principle:
Principle #15Dynamics

3Reliability

If motion detection is used to prevent relay attacks, then security is improved, but device complexity increases

Engineering Contradiction:
ImprovesecurityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The electronic key uses its own motion sensor to detect its movement status, making the system self-sufficient for security verification. The key independently determines whether it is being moved toward the vehicle without requiring external verification systems, thus improving security while minimizing additional complexity.

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Effectively prevents relay attacks while enhancing user comfort by ensuring the key is not disabled when intended to be used, reducing the risk of locking the key inside the vehicle and minimizing energy consumption.

Implementation Method 1

a motion sensor configured to detect a movement of the electronic key

Methodology Applied
Scientific EffectMotion detection: Accelerometer

Data Source

PatentEP3671668B1Electronic key and method for operating an electronic key
Publication Date: 2023.06.07 CONTINENTAL AUTOMOTIVE TECHNOLOGIES GMBH
  • EP3671668B1 patent drawingFigure 1~2
  • EP3671668B1 patent drawingFigure 3~4
  • EP3671668B1 patent drawingFigure 5~7

AI summary

An electronic key (30) for a vehicle (10) comprises a motion sensor (31) configured to detect a movement of the electronic key (30), a processing unit (32), and a transceiver unit (33) configured to transmit signals to and receive signals from the vehicle (10). Upon occurrence of a triggering event, the processing unit (32) is configured to, if it is detected by the motion sensor (31) that the electronic key (30) is not moving, and if the electronic key (30) is detected to be outside the vehicle (10), switch the transceiver unit (33) from an enabled state to a disabled state such that no signals may be received from the vehicle (10). The processing unit (32) is further configured to, if it is detected by the motion sensor (31) that the electronic key (30) is not moving, and if the electronic key (30) at the same time is detected to be inside the vehicle (10), keep the transceiver unit (33) in the enabled state.