Send the Key in Cleartext: Halving Key Consumption while Preserving Unconditional Security in QKD Authentication
Abstract
Quantum Key Distribution (QKD) protocols require Information-Theoretically Secure (ITS) authentication of the classical channel to preserve the unconditional security of the distilled key. Standard ITS schemes are based on one-time keys: once a key is used to authenticate a message, it must be discarded. Since QKD requires mutual authentication, two independent one-time keys are typically consumed per round, imposing a non-trivial overhead on the net secure key rate. In this work, we present the authentication-with-response scheme, a novel ITS authentication scheme based on -Almost Strongly Universal (-ASU) functions, whose IT security can be established in the Universal Composability (UC) framework. The scheme achieves mutual authentication consuming a single one-time key per QKD round, halving key consumption compared to the state-of-the-art.
Cite
@article{arxiv.2603.25496,
title = {Send the Key in Cleartext: Halving Key Consumption while Preserving Unconditional Security in QKD Authentication},
author = {Claudia De Lazzari and Francesco Stocco and Edoardo Signorini and Giacomo Fregona and Fernando Chirici and Damiano Giani and Tommaso Occhipinti and Guglielmo Morgari and Alessandro Zavatta and Davide Bacco},
journal= {arXiv preprint arXiv:2603.25496},
year = {2026}
}