Efficient Key Generation by Exploiting Randomness from Channel Responses of Individual OFDM Subcarriers

Junqing Zhang, Alan Marshall, Roger Woods, Trung Q. Duong

Research output: Contribution to journalArticlepeer-review

54 Citations (Scopus)
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Abstract

Key generation from the randomness of wireless channels is a promising technique to establish a secret cryptographic key securely between legitimate users. This paper proposes a new approach to extract keys efficiently from channel responses of individual orthogonal frequency-division multiplexing (OFDM) subcarriers. The efficiency is achieved by (i) fully exploiting randomness from time and frequency domains and (ii) improving the cross-correlation of the channel measurements. Through the theoretical modelling of the time and frequency autocorrelation relationship of the OFDM subcarrier's channel responses, we can obtain the optimal probing rate and use multiple uncorrelated subcarriers as random sources. We also study the effects of non-simultaneous measurements and noise on the cross-correlation of the channel measurements. We find the cross-correlation is mainly impacted by noise effects in a slow fading channel and use a low pass filter (LPF) to reduce the key disagreement rate and extend the system's working signal-to-noise ratio range. The system is evaluated in terms of randomness, key generation rate, and key disagreement rate, verifying that it is feasible to extract randomness from both time and frequency domains of the OFDM subcarrier's channel responses.
Original languageEnglish
Pages (from-to)2578 - 2588
Number of pages10
JournalIEEE Transactions on Communications
Volume64
Issue number6
DOIs
Publication statusPublished - 07 Apr 2016

Keywords

  • Physical layer security
  • Key generation
  • OFDM
  • Time and frequency autocorrelation
  • Channel reciprocity

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