Broadband optical time-domain reflectometry for security analysis of quantum key distribution

TL;DR

This paper introduces a novel optical time-domain reflectometry method to analyze the security of quantum key distribution systems against Trojan-horse attacks over a broad spectral range, providing detailed reflectance data and security assessment.

Contribution

It presents the first wide spectral range OTDR setup for security analysis of QKD systems, enabling detailed spectral reflectance measurements and security evaluation against side-channel attacks.

Findings

Achieved centimeter-level resolution in spectral reflectance analysis.

Demonstrated the first wide spectral range OTDR setup for QKD security.

Provided a comprehensive security analysis considering spectral data.

Abstract

In this paper, we present a method for security analysis against the Trojan-horse attacks (THA) launched to a practical fiber-based quantum key distribution (QKD) system across a wide spectral range. To achieve this, we utilize optical time-domain reflectometry (OTDR) for the spectral reflectance analysis in the near-infrared range 1100 - 1800 nm with centimeter-level resolution and with a noise floor down to -80 dB. Finally, the total theoretical-security analysis against the THA side channel considering the spectral reflectance and transmittance data over this spectral range is conducted. To the best of our knowledge, our OTDR setup and the corresponding results are the first of their kind in a wide spectral range.