Hands-Free Key Motion Gating Against Vehicle Relay Attacks

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing keyless entry systems are vulnerable to relay attacks and require manual intervention or production modifications to address signal absence during vehicle assembly, leading to inefficiencies and security risks.

Innovation Solution

A hands-free key equipped with a wireless communication interface and motion sensor that sends unlock commands only when the key is within a threshold distance and detects movement, with automatic reactivation of unlock functionality after a specified time or event, preventing relay attacks and eliminating the need for manual intervention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the keyless entry system is disabled when stationary away from the vehicle for a specified period to protect against relay attacks, then security against relay attacks is improved, but the system fails to unlock the vehicle when the key is stationary inside the vehicle during production

Engineering Contradiction:
Improvesecurity against relay attacksVSAvoidvehicle unlocking capability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system performs preliminary actions during vehicle production to establish that the key is in a valid stationary position inside the vehicle. This preliminary validation allows the system to later distinguish between legitimate stationary keys during production and suspicious stationary keys during normal operation, resolving the contradiction by enabling unlocking during production while maintaining security during normal use.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The keyless entry system uses its own motion sensor and distance measurement capabilities to automatically determine whether the key is legitimately stationary inside the vehicle during production. This self-service approach eliminates the need for manual intervention or production modifications, allowing the system to autonomously resolve the contradiction between security and operational capability.

Inventive Principle:
Principle #25Self-service

2Reliability

If manual intervention is required to move the key to deactivate it and unlock the vehicle during production, then the key can be deactivated when stationary, but production complexity and time increase

Engineering Contradiction:
Improvekey deactivation functionalityVSAvoidproduction efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The keyless entry system autonomously manages its own deactivation and reactivation states using internal motion sensors and distance measurements, eliminating the need for manual key movement or production line interventions. This self-service capability maintains reliability while preserving production efficiency.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system performs preliminary validation during production to establish the key's legitimate stationary position, enabling automatic deactivation and reactivation without manual intervention. This preliminary action resolves the contradiction by maintaining reliability while avoiding productivity losses.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If the key sends unlock commands continuously when within threshold distance, then vehicle access is improved, but the system becomes vulnerable to relay attacks

Engineering Contradiction:
Improvevehicle access convenienceVSAvoidprotection against relay attacks
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system dynamically adjusts its unlock command sending behavior based on real-time motion sensor detection and distance measurements. When motion is detected or distance is within threshold, unlock commands are sent for convenient access. When stationary beyond threshold, sending is inhibited to prevent relay attacks. This dynamic adaptation resolves the contradiction between access convenience and security.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system uses feedback from motion sensors and distance measurements to control unlock command transmission. This feedback mechanism enables the system to automatically adjust between convenient access mode and security mode, resolving the contradiction by making unlock behavior conditional on real-time sensor data rather than continuous or manual control.

Inventive Principle:
Principle #23Feedback

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

Enables secure and automated vehicle access without manual intervention, ensuring protection against relay attacks and minimizing production disruptions.

Implementation Method 1

a hands-free key (100) comprising a wireless communication interface (120) and a motion sensor (130)

Methodology Applied
Scientific EffectAccelerometer: Accelerometer

Implementation Method 2

measuring the amplitude of a radio signal emitted by the vehicle, for example received by the wireless communication interface

Methodology Applied
Scientific EffectRadio signal transmission: Electromagnetic Induction

Data Source

PatentEP4377161B1Method for opening a vehicle and associated hands-free key
Publication Date: 2026.03.04 STELLANTIS AUTO SAS
  • EP4377161B1 patent drawingFigure 1
  • EP4377161B1 patent drawingFigure 2

AI summary

A method for opening a vehicle implemented by a hands-free key (100), comprising the following steps: - Sending an opening command via a wireless communication interface (120) based on security data when an estimated distance between the key (100) and the vehicle is below a threshold, - Blocking the sending of the opening command if no movement of the key has been detected by a motion sensor (130) for a determined time while the estimated distance is above the threshold, and then - Unblocking the sending of the opening command when a movement of the key (100) is detected by the motion sensor (130), characterized in that it comprises the following steps - Deactivating the blocking based on a deactivation event, and then - Reactivating the blocking upon detection of a reactivation event.