Low-power Secret-key Agreement over OFDM

TL;DR

This paper proposes a low-power secret-key agreement scheme over OFDM channels using LDPC codes, demonstrating its practicality and effectiveness even with limited eavesdropper channel knowledge.

Contribution

It introduces a low-power randomness sharing method for OFDM links with LDPC-based reconciliation, suitable for fading channels and limited eavesdropper information.

Findings

Achieves practical secret-key rates at low power levels.

LDPC codes effectively facilitate information reconciliation.

Outage formulation enables operation with only statistical eavesdropper channel knowledge.

Abstract

Information-theoretic secret-key agreement is perhaps the most practically feasible mechanism that provides unconditional security at the physical layer to date. In this paper, we consider the problem of secret-key agreement by sharing randomness at low power over an orthogonal frequency division multiplexing (OFDM) link, in the presence of an eavesdropper. The low power assumption greatly simplifies the design of the randomness sharing scheme, even in a fading channel scenario. We assess the performance of the proposed system in terms of secrecy key rate and show that a practical approach to key sharing is obtained by using low-density parity check (LDPC) codes for information reconciliation. Numerical results confirm the merits of the proposed approach as a feasible and practical solution. Moreover, the outage formulation allows to implement secret-key agreement even when only statistical knowledge of the eavesdropper channel is available.