Signal Processing System for Passive Keyless Entry Relay Attack Prevention

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Solution Overview

Problem

Passive Keyless Entry (PKE) systems are vulnerable to relay attacks, where malicious individuals can deceive the system into thinking a key fob is in proximity by relaying communication signals over long distances, without the owner's knowledge, due to the lack of effective distance verification.

Innovation Solution

A signal processing system that receives and verifies multipath components to determine the authenticity of the key fob's proximity by correlating the earliest multipath component with a reference signal derived from the strongest components, ensuring the consistency of the signal without demodulating the earliest multipath component, thereby preventing false proximity verification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If relay attack prevention is implemented by verifying signal consistency, then security against relay attacks is improved, but system complexity increases due to additional verification requirements

Engineering Contradiction:
Improvesecurity against relay attacksVSAvoidverification system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary verification mechanism that correlates multipath components without requiring full demodulation. The verification unit acts as a mediator between signal reception and authentication, using correlation of multipath components (particularly the earliest component) to detect relay attacks. This intermediary approach provides security verification while avoiding the complexity of complete signal demodulation and processing.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the earliest multipath component is demodulated for verification, then verification accuracy is improved, but processing time and computational load increase

Engineering Contradiction:
Improveverification accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts only the essential verification information from the earliest multipath component through correlation operations, rather than performing complete demodulation. The verification unit correlates the earliest multipath component with reference signals to extract consistency information sufficient for relay attack detection. This extraction approach maintains verification accuracy while significantly reducing processing time and computational requirements compared to full demodulation.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If multiple multipath components are verified through full demodulation, then verification reliability is improved, but energy consumption increases

Engineering Contradiction:
Improveverification reliabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies partial action by performing correlation verification on multipath components without full demodulation. The verification unit correlates selected multipath components (especially the earliest one) with reference signals to obtain sufficient verification information. This partial verification approach provides adequate reliability for relay attack detection while consuming significantly less energy than complete demodulation of all multipath components.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3255805B1Signal processing system and method
Publication Date: 2020.09.02 NXP BV
  • EP3255805B1 patent drawingFigure 1~2
  • EP3255805B1 patent drawingFigure 3
  • EP3255805B1 patent drawingFigure 4

AI summary

According to a first aspect of the present disclosure, a signal processing system is provided, comprising: a receiving unit configured to receive at least one signal that comprises a plurality of multipath components; a verification unit configured to correlate at least one multipath component under test with a reference signal derived from one or more of said plurality of multipath components. According to a second aspect of the present disclosure, a corresponding signal processing method is conceived. According to a third aspect of the present disclosure, a corresponding computer program is provided.