Propagation Channel-Based Secure Association Method

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Solution Overview

Problem

Existing data transmission security methods in communication networks rely on prior distribution and management of keys, which becomes problematic for large-scale distribution and non-disclosure, especially in cellular radio networks.

Innovation Solution

A method for secure association between transmitters and receivers using the properties of the propagation channel, without pre-shared keys, through initial and iterative transmissions of interrogation and acknowledgment signals, measuring, and quantifying the channel coefficients to establish a univalent and unambiguous association.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cryptographic processes with prior distribution of keys are used to secure data transmission, then data transmission security is improved, but key distribution and management complexity increases and large-scale distribution becomes problematic

Engineering Contradiction:
Improvedata transmission securityVSAvoidkey distribution and management
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the security mechanism from the traditional key-based cryptographic system and replaces it with a physical channel-based identification system. Instead of using shared keys for authentication, the system uses unique propagation channel characteristics (multipath profiles) as identifiers, thereby removing the complex key distribution and management infrastructure while maintaining security.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system enables transmitters and receivers to automatically identify and authenticate each other through self-measurement of propagation channel characteristics. Each device independently measures the multipath profile of the channel between them, and this measured profile serves as the authentication credential, eliminating the need for external key distribution services or centralized authentication authorities.

Inventive Principle:
Principle #25Self-service

2Reliability

If pre-shared keys are used for authentication, then association security is improved, but vulnerability to key disclosure increases

Engineering Contradiction:
Improveassociation securityVSAvoidkey disclosure vulnerability
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the traditionally harmful effect of channel variations (which cause fading and interference) into a beneficial security feature. The unique multipath profile created by the physical environment (buildings, terrain, obstacles) becomes an unclonable authentication credential. Since these channel characteristics are physically determined and constantly changing, they cannot be replicated or disclosed, transforming environmental factors into security assets.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent replaces the logical/key-based authentication system with a physical/measurement-based system. Instead of exchanging cryptographic keys through software protocols, the system uses physical measurements of electromagnetic wave propagation characteristics (time delays, signal strengths, arrival angles) to establish authentication, thereby eliminating vulnerabilities associated with key storage and transmission.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If channel measurements and quantification are performed to establish univalent association, then association accuracy is improved, but measurement and processing complexity increases

Engineering Contradiction:
Improveassociation accuracyVSAvoidmeasurement and processing
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs measurements of channel characteristics but does not require complete or exhaustive measurement of all possible parameters. Instead, it focuses on measuring specific key features of the multipath profile (such as time delays and signal strengths of dominant paths) that are sufficient for accurate identification. This partial measurement approach achieves high association accuracy while limiting processing complexity.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent transforms the continuous, complex channel impulse response into a simplified discrete representation through quantification. By converting the continuous channel characteristics into discrete parameters (such as time delay bins and signal strength levels), the system maintains measurement precision for identification purposes while dramatically reducing the complexity of storage, comparison, and processing operations.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3398307B1Method of univalent and one-to-one association between emitters and receivers of transmission on the basis of the propagation channel
Publication Date: 2020.03.25 THALES SA
  • EP3398307B1 patent drawingFigure 1~2
  • EP3398307B1 patent drawingFigure 3
  • EP3398307B1 patent drawingFigure 3

AI summary

Method of univalent and one-to-one association on the basis of the propagation channel (AU_CP) between a first user A and a second user B each furnished with one or more transmission emitters/receivers (NA in number and denoted A1... ANA for the user A, NB in number and denoted B1... BNB for the user B), the said association, carried out without previously known or shared key, being secure in relation to any unauthorized third party E (likewise furnished with receivers and if appropriate with emitters) even before the establishment of the transmission protocol between the users A and B, with the aid of prior transmissions of interrogation signals and of acknowledgement signals and with the aid of measurements of the propagation channels between the emitters receivers of A and those of B by virtue of these interrogation and acknowledgement signals, the said association being intended to subsequently facilitate the establishment of a transmission, protected in relation to E, between the users A and B as well as the identification of A by B and of B by A, the checking of confidentiality and the checking of integrity of the messages exchanged by A and B.