Secret Key Agreement by Soft-Decision of Signals in Gaussian Maurer's Model

Masashi NAITO  Shun WATANABE  Ryutaroh MATSUMOTO  Tomohiko UYEMATSU  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E92-A   No.2   pp.525-534
Publication Date: 2009/02/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E92.A.525
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: Information Theory
advantage distillation,  AWGN,  information theoretic security,  key agreement,  privacy amplification,  public discussion,  

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We consider the problem of secret key agreement in Gaussian Maurer's Model. In Gaussian Maurer's model, legitimate receivers, Alice and Bob, and a wire-tapper, Eve, receive signals randomly generated by a satellite through three independent memoryless Gaussian channels respectively. Then Alice and Bob generate a common secret key from their received signals. In this model, we propose a protocol for generating a common secret key by using the result of soft-decision of Alice and Bob's received signals. Then, we calculate a lower bound on the secret key rate in our proposed protocol. As a result of comparison with the protocol that only uses hard-decision, we found that the higher rate is obtained by using our protocol.