arXiv subjects

Jialei Su

Publications and source records attributed to Jialei Su.

3 recordsLinked to original sources

arXiv2025

Deep Anomaly Detection for Active Attacks on the Receiver in Quantum Key Distribution

Traditional countermeasures against attacks targeting the receiver in quantum key distribution (QKD) systems often suffer from poor compatibility with deployed infrastructure, the risk of introducing new vulnerabilities, and limited applicability to specific types of active attacks. In this work, we propose an anomaly detection (AD) model based on one-class machine learning to address active attacks targeting the receiver. By constructing a dataset from the QKD system's operational states, the AD model learns the characteristics of normal behavior under secure conditions. When an active attack occurs, the system's state deviates from the learned normal patterns and is identified as anomalous by the model. Experimental results show that the AD model achieves an area under the curve (AUC) exceeding 99%, effectively safeguarding the receiver of the QKD system. Compared to traditional approaches, our model can be deployed with minimal cost in existing QKD networks without requiring additional optical or electrical components, thus avoiding the introduction of new side channels. Furthermore, unlike multi-class machine learning algorithms, our approach does not rely on prior knowledge of specific attack types and is potentially able to detect unknown active attacks. These advantages-generality, ease of deployment, low cost, and high accuracy-make our model a practical and effective tool for protecting the receiver of QKD systems against active attacks.

quant-ph↗

arXiv2025

Security analysis of orthogonal state attack on a high-speed quantum key distribution system

High-speed quantum key distribution (QKD) systems have achieved repetition frequencies above gigahertz through advanced technologies and devices, laying an important foundation for the deployment of high-key-rate QKD system. Although these advanced systems may introduce potential loopholes, an eavesdropper Eve is challenging to exploit them by performing the intercept-resend attacks due to the limited time window under high repetition frequency. However, here, we propose a security analysis model of orthogonal state attacks that do not require intercept-resend operation on the key rate of a QKD system. Under this framework, we propose a muted attack and experimentally verify the feasibility of the attack using a 1 GHz single-photon avalanche detector (SPAD). By sending hundreds of photons each time, Eve can mute Bob's SPADs to control the overall detection response of the QKD receiver, allowing her to learn nearly all the keys. Furthermore, we use this security model to simulate the overestimated key rates of the QKD system under orthogonal state attacks, including both the muted attack and the dead-time attack. This work theoretically and experimentally shows a timely case of the security vulnerability in the high-speed QKD system.

quant-ph↗

arXiv2025

Quantifying the Upper Limit of Backflash Attack in Quantum Key Distribution

Quantum key distribution (QKD) provides information-theoretic security grounded in the fundamental laws of physics. Nevertheless, practical imperfections can introduce side channels that expose QKD systems to quantum hacking, especially passive attacks that are inherently difficult to detect. In this study, we experimentally and theoretically investigate the upper limit of the backflash attack-a representative passive side-channel threat. Using a fully equipped fiber-based QKD receiver, we demonstrate the feasibility of the attack and reveal its limited capability in distinguishing quantum states. We further develop a theoretical framework to quantify the maximum distinguishability achievable by an eavesdropper, taking into account the broadband spectral nature of backflash photons. The analysis shows that Eve can extract effective key information from at most 95.7% of the backflash photons. Based on these findings, we evaluate the secure key rate of a decoy-state BB84 QKD system under backflash attack. Our results provide a quantitative assessment of the vulnerability of QKD systems to backflash emissions and offer a general methodology to evaluate the practical security of QKD systems.

quant-ph↗