Vehicle Access Verification via Dynamic Frequency Pattern

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Solution Overview

Problem

Keyless entry systems for vehicles are vulnerable to unauthorized access through malicious extension of the radio link using transceivers, as the vehicle does not detect manipulation of the communication signals, allowing unauthorized individuals to gain access.

Innovation Solution

The method involves encoding data with a specific algorithm and transmitting it via a radio transmission device, allowing only the control device and ID transmitter to determine the frequency pattern for communication, making it impossible for unauthorized transceivers to follow the communication, and detecting deviations in carrier frequencies to prevent malicious link extensions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If keyless entry systems use short-range radio communication between ID transmitter and control device, then vehicle access security is improved, but the system becomes vulnerable to malicious extension attacks using transceivers

Engineering Contradiction:
Improvevehicle access securityVSAvoidvulnerability to transceiver extension attacks
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by dynamically varying the carrier frequency of radio communication based on a frequency pattern determined from encoded data. The control device and ID transmitter both calculate the frequency pattern from the same encoded data, ensuring they operate on the same frequency. Unauthorized transceivers cannot intercept or extend the communication because they cannot determine the frequency pattern without the encoded data and algorithm, thus resolving the vulnerability to extension attacks while maintaining secure short-range communication

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements preliminary action by encoding data with an algorithm before radio transmission to generate the frequency pattern. This encoding step occurs in advance of the actual communication, ensuring that only the authorized control device and ID transmitter (which possess the encoding algorithm) can determine the correct frequency pattern. This preliminary encoding prevents unauthorized transceivers from predicting or following the frequency changes, thereby preventing malicious link extension before it can occur

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the control device and ID transmitter use a frequency pattern determined from encoded data, then unauthorized transceivers cannot follow the communication, but the system complexity increases

Engineering Contradiction:
Improvecommunication securityVSAvoidencoding algorithm and frequency pattern determination
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies universality by implementing a symmetric encoding algorithm that both the control device and ID transmitter possess. This same algorithm serves multiple functions: encoding the initial data, determining the frequency pattern for radio communication, and enabling both devices to independently calculate the correct frequency without requiring separate key management systems. This multi-functionality reduces overall system complexity while maintaining security

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

Solution Approach 2:

The patent uses encoded data as an intermediary element that mediates between the control device and ID transmitter. This encoded data serves as a shared secret that both parties use to independently determine the frequency pattern. The intermediary encoded data eliminates the need for complex pre-shared key management or frequent authentication handshakes, simplifying the system architecture while ensuring that only authorized devices can participate in the frequency-hopped communication

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the receiving device tunes to carrier frequencies according to the frequency pattern, then only authorized communication is received, but the detection and measurement difficulty increases

Engineering Contradiction:
Improveauthorized communication onlyVSAvoidfrequency pattern tracking
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent implements feedback by having the control device monitor the radio communication to verify that the ID transmitter is responding on the correct frequency pattern. The control device encodes data, determines the frequency pattern, and then listens for responses at those frequencies. If the ID transmitter responds correctly on the expected frequencies, this confirms authorized communication. This feedback mechanism simplifies detection compared to passive frequency hopping, as the control device actively verifies compliance with the frequency pattern

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

This method enhances the security of vehicle access by ensuring only authorized individuals can communicate within the specific frequency pattern, preventing unauthorized access and maintaining the integrity of the communication link.

Implementation Method 1

sends the encoded first data in a first message with the aid of a radio transmission device coupled to the control device

Methodology Applied
Scientific EffectRadio wave transmission: Electromagnetic Induction

Implementation Method 2

The first message is received in an ID transmitter assigned to the vehicle, and the first data are decoded in the ID transmitter

Methodology Applied
Scientific EffectElectromagnetic signal reception: Electromagnetic Induction

Data Source

PatentEP1747955B1Verification method for a vehicle access legitimation
Publication Date: 2008.03.12 HUF HÜLSBECK & FÜRST GMBH & CO KG
  • EP1747955B1 patent drawingFigure 1
  • EP1747955B1 patent drawingFigure 2

AI summary

The method involves determining frequency sample independent of coded data in a message received by an ID-sensor. A radio communication is implemented between a radio transmitting device and a receiving device of a control device. A carrier frequency of the transmitting device is selected based on the sample, during the transmission of another message with coded another data. The receiving device is adjusted in dependent of the former data at the carrier frequency according to the sample. The authentication for the access to a vehicle is found in dependent of the latter data.