Abstract

Decode-and-forward and amplify-and-forward relay attacks are a powerful tool for defeating challenge-response authentication protocols. Current solutions for detecting these relay attacks utilize round-trip time distance-bounding. Unfortunately, secure implementations of distance-bounding require dedicated ultra-wideband hardware that only provide low data rates and operate at relatively short distances. In this paper we propose two novel symmetric-key challenge-response authentication protocols that can detect either a decode-andforward relay attack or prevent a decode-and-forward and detect an amplify-and-forward relay attack. Both protocols utilize the channel state information in a far-field communication system to perform the detection. The first protocol utilizes the correlation of the adjusted channel frequency response to detect decode-and-forward relay attacks. The second protocol prevents decode-and-forward relay attacks through the use of randomized pilots, and detects amplify-and-forward relay attacks by classifying the distribution of the channel frequency response that is caused by multiple relays. The protocols utilize orthogonal frequency division multiplexing to estimate the channel frequency response between the legitimate communicating parties to identify if a relay attack is occurring in a physical-layer challenge-response authentication protocol. The proposed protocols can be leveraged on many existing hardware platforms and can simultaneously support high data rates. To evaluate the performance of the protocol, MATLAB simulations are done to gather Monte-Carlo results on performance criterion.