Wireless FTM Distance Bounding Authentication Protocol
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Solution Overview
Problem
Existing Fine Timing Measurement (FTM) security protocols in wireless communications face challenges such as high computational resource requirements and vulnerabilities to attacks like relay/replay/man-in-the-middle attacks, particularly in proximity-based systems where devices may not be pre-associated with secret keys.
Innovation Solution
A method combining aspects of FTM and Distance Bounding protocols, using a verifier device to transmit challenge bits and measure round trip times, with authentication based on predicted response bits calculated via keyed or pseudo-random hash functions, and optionally using skip bits to enhance security against unauthorized access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Diffie-Hellman (DH) or DH with Ephemeral keys (DHE) protocols are used for FTM security, then security authentication is provided, but computational resource requirements become substantial
Solution Approach 1:
The patent merges FTM protocol with Distance Bounding (DB) protocol to create a hybrid authentication mechanism. The DB protocol provides lightweight cryptographic challenges that are computationally efficient while maintaining security, combining the timing measurement capabilities of FTM with the security efficiency of DB to resolve the contradiction between security and computational resource usage
Solution Approach 2:
The patent changes the cryptographic parameters by using challenge-response mechanisms with challenge bits and predicted response bits instead of full DH key exchange. This parameter change reduces computational complexity from O(log p) modular exponentiation operations to simpler bitwise operations and hash function evaluations, maintaining security while reducing energy consumption
2Reliability
If pre-established security association is used in DH protocols, then security authentication is enabled, but device complexity increases due to pre-association requirements
Solution Approach 1:
The patent uses preliminary action by pre-calculating and storing challenge-response pairs in lookup tables during device manufacturing or initialization. This allows the devices to perform fast authentication without needing to establish security associations dynamically, reducing runtime complexity while maintaining security through pre-prepared cryptographic materials
Solution Approach 2:
The patent uses copying by having both verifier and prover devices store identical copies of secret keys and pre-computed challenge-response pairs. This eliminates the need for complex key exchange protocols during runtime, as both parties already possess the necessary cryptographic materials, simplifying the authentication process while maintaining security
3Productivity
If Distance Bounding protocol is used, then computational efficiency is improved, but vulnerability to relay/replay/man-in-middle attacks increases
Solution Approach 1:
The patent applies dynamics by making the authentication protocol adaptive and stateful rather than static. The verifier maintains session state including expected challenge-response pairs and timing information, allowing it to dynamically detect and reject replay attacks. The protocol transitions through defined states that track the authentication flow, enabling detection of abnormal patterns indicative of relay or man-in-middle attacks while maintaining computational efficiency
Solution Approach 2:
The patent implements feedback mechanisms where the verifier continuously monitors authentication exchanges and provides feedback by accepting or rejecting challenge responses based on timing validation and cryptographic verification. This feedback loop enables real-time detection of relay and replay attacks, as unauthorized devices will fail to meet timing constraints or produce incorrect cryptographic responses, thereby securing the protocol against these threats while preserving computational efficiency
Data Source
AI summary
System and method using distance bounding to provide security in fine timing measurement (FTM) communications including authenticating a prover device at a verifier device, including: transmitting from a verifier device, through the wireless interface, a sequence of challenge bits for a prover device, each challenge bit being transmitted in a respective FTM frame; receiving, at the verifier device, FTM acknowledgment frames; determining, for at least some of the received FTM acknowledgement frames, respective round trip time (RTT) measurements; determining, for at least some of the received FTM acknowledgement frames, whether the included response bit matches a predicted response bit; and authenticating the prover device based on the determined RTT measurements and the determined response bit matches.