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arXiv · 2508.15197

The practical issues of side-channel-secure quantum key distribution

Cong Jiang·Xiao-Long Hu·Zong-Wen Yu·Hai Xu·Xiang-Bin Wang
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Abstract

Quantum Key Distribution (QKD) leverages the principles of quantum mechanics to provide theoretically unconditional security for cryptographic key sharing. However, practical implementations remain vulnerable due to non-ideal devices and potential security loopholes at both the source and detection sides of QKD systems. The side-channel-secure (SCS) protocol addresses these challenges by encoding bits in vacuum and non-vacuum states and introducing a third-party measurement node, thereby repelling attacks targeting the detection side as well as external lab attacks on the source side. In this work, we consider the state-dependent correlated errors and Trojan-horse attack while preserving the SCS protocol's key advantage-specifically, requiring only upper bounds on intensities characterization without needing a full description of quantum states in infinite dimensions. Numerical results demonstrate that when the reflected light intensity from Trojan-horse attacks falls below $10^{-6}$, Eve can scarcely extract additional key information from the reflections. This work makes the SCS protocol more practical.

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Cong Jiang, Xiao-Long Hu, Zong-Wen Yu, Hai Xu, Xiang-Bin Wang. 2025-08-21. The practical issues of side-channel-secure quantum key distribution. https://arxiv.org/abs/2508.15197

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