FTM Location Configuration Authentication for Trusted AP Positioning

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Solution Overview

Problem

Current Fine Time Measurement (FTM) Location Configuration Information (LCI) exchanges in wireless networks lack authentication and geographical validation, making it difficult for client devices to determine the legitimacy of Access Points (APs) providing LCI, which can lead to inaccurate location determinations and potential attacks from malicious APs.

Innovation Solution

Implement a system where a controller obtains a key-pair from a Certificate Authority (CA) to authenticate APs, providing a public key certificate with venue location, allowing client devices to verify the authenticity of APs by decrypting a hash of the LCI using the public key, ensuring the APs are legitimate and within a tolerated location threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If FTM LCI exchanges are implemented without authentication, then the system is simpler and easier to operate, but the reliability and security of location data is compromised

Engineering Contradiction:

Improvereliability of location dataVSAvoidcomplexity of authentication system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements preliminary action by having the controller obtain a key-pair and venue location from a Certificate Authority before the FTM LCI exchanges occur. This pre-established authentication infrastructure allows the AP to later provide cryptographically signed location information without requiring complex real-time authentication during the actual location measurement process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses a Certificate Authority as an intermediary to issue certificates that bind the AP's identity to its location. This intermediary approach allows the system to maintain simplicity at the AP-client level while ensuring reliability through a trusted third party that validates and certifies the AP's location information before deployment.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If authentication and geographical validation are implemented, then the security and accuracy of LCI exchanges is improved, but the complexity of the system increases

Engineering Contradiction:

Improveaccuracy of location determinationVSAvoidcomplexity of validation system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs geographical validation in advance by obtaining the venue location from the Certificate Authority before the FTM process. This preliminary validation ensures that only APs with certified location information can provide accurate location data, while the actual FTM measurement process remains simple and unchanged.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces complex mechanical or procedural validation systems with cryptographic verification. Instead of requiring complex checks during FTM exchanges, the system uses public key cryptography where the client simply verifies the digital signature on the LCI data, providing high measurement precision through mathematically secure verification rather than complex validation logic.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Object-affected harmful factors

If cryptographic verification is implemented, then the protection against fraudulent APs is enhanced, but the processing requirements and system complexity increase

Engineering Contradiction:

Improveprotection against malicious APsVSAvoidcomplexity of cryptographic system

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent uses disposable, pre-computed cryptographic signatures that are embedded in the LCI data. These digital signatures are created once during certificate issuance and can be verified multiple times without additional computational overhead during FTM exchanges. The cryptographic protection is lightweight and does not require continuous complex processing.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The Certificate Authority acts as an intermediary that performs the heavy cryptographic work of key generation and signature creation before deployment. This shifts the computational complexity from the AP and client devices to a centralized authority, allowing the actual FTM system to use simple verification operations while still enjoying strong cryptographic protection against fraudulent APs.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12520145B2Fine time measurement location configuration information protection

Publication Date: 2026.01.06 CISCO TECHNOLOGY INC

AI summary

Fine Time Measurement (FTM) Location Configuration Information (LCI) protection and, specifically, FTM LCI protection with authentication and selective client enablement may be provided. To perform FTM LCI protection, a controller may first obtain a key-pair including a public key and a private key from a Certificate Authority (CA). The controller my determine a venue location where an Access Point (AP) is located. The controller may send a Certificate Signing Request (CSR) with the venue location to the CA. In response to sending the CSR, the controller may receive a public key certificate from the CA, wherein the public key certificate includes the venue location. The AP may receive a request for Location Configuration Information (LCI) from a Station (STA), wherein the LCI includes an AP location. The AP creates a hash of LCI of the AP using the private key and sends the LCI and the hash to the STA.