TL;DR
A dynamic evolutionary attack detection scheme for practical QKD, in which Eve’s attack feature could be vectorized by a well-designed embedding model and dynamically self-update to an attack feature vector database, which significantly improves the generalization capability of quantum attack detection and promotes the practical development of QKD.
This paper proposes a quantum k-nearest neighbor (QkNN)-based multiclass attack detection framework for CVQKD systems that establishes a direct connection between attack detection and secret key generation, enabling a more realistic security evaluation for practical CVQKD systems.
Continuous-variable quantum key distribution (CVQKD) has attracted extensive attention due to its compatibility and low costs. However, bandwidth mismatch exists to varying degrees between the transmitter and receiver. This may prevent frequency components carrying modulation information from being fully perceived by the legitimate party. In this paper, we identify a practical security loophole caused by bandwidth mismatch and propose a corresponding spectral attack scheme. Different from previous approaches that exploit security loopholes to conceal the excess noise introduced by intercept-resend attacks, this scheme can directly obtain raw-key information without introducing additional disturbances. A proof-of-principle attack on a CVQKD system with filtering operation is constructed to verify the feasibility. Experimental results indicate that Eve can obtain enough information to render the system insecure if this practical security loophole is ignored. Based on the identified security loophole, corresponding defense strategies are proposed. This work helps bridge the gap between theoretical models and practical implementations, providing a reference for defense design in practical quantum communication systems.
Federated Learning (FL) enables collaborative model learning without the need to share raw data, but its communication links are vulnerable to interception, replay, and man-in-the-middle (MITM) attacks. The existing key exchange methods rely on computational hardness assumptions, which can be broken by post-quantum attackers. In this paper, a secure federated learning framework improved by Quantum Key Distribution (QKD) is proposed, which integrates BB84-like quantum key generation and authenticated encryption on a per-round basis, as well as Quantum Bit Error Rate (QBER)-assisted intrusion detection. A new cryptographic key is produced in each federated round, making it immune to replay attacks and allowing for detection of tampering. Theoretical calculations show that intercept-resend attacks lead to a minimum expected QBER of 25%, making it easier to detect statistically. Experimental results on the MNIST dataset show near-perfect detection rates for MITM and replay attacks, with QBER values increasing from about 1% (serving as a benign scenario) to about 26% in an attack scenario. Communication overhead is kept below 10%, with negligible computational latency compared to local training. The experiments show that the use of QKD-based key refresh improves FL communication security while still ensuring model convergence.
Twin-field (TF) quantum key distribution (QKD) can overcome the fundamental rate-loss bound of repeaterless QKD, enabling secure communication over long distances. However, in practical implementations, its security relies on accurate intensity modulation, which may be compromised by source imperfections and light-injection attacks. In this work, we investigate the security of the NPP TF-QKD protocol in the presence of imperfect intensity modulation, focusing on Trojan-horse attacks and induced photorefractive attacks. By employing the reference technique, we establish a finite-key security proof that explicitly incorporates this source-side information leakage. Numerical simulations show that with realistic transmitter isolation, the NPP TF-QKD protocol can still surpass the rate-loss bound and achieve secret-key rates close to the ideal case. Our results further demonstrate strong robustness against modulation deviations induced by photorefractive effects. These findings confirm the practical security of TF-QKD under realistic source imperfections and provide quantitative guidance for the design of secure quantum communication systems.
Quantum Key Distribution is theoretically possible secure communication through the use of quantum-mechanical principles, such as superposition, measurement disturbance, and others. The BB84 and E91 protocols provide security by leveraging quantum principles against classical eavesdropping; nevertheless, the current implementation of QKD is vulnerable to photon-number-splitting attacks, imperfections in the devices used, and environmental quantum noise. Improving practical resistance to all of those is crucial for providing secure real-life use of QKD. Extending the current state-of-the-art through further development of research on eavesdropper detection and improvement of qubit-based security mechanisms, this research aims to develop the state-of-the art further by introducing a decoy-state BB84 framework and analyzing the behavior of such a system under realistic quantum noise. To find solutions to these problems, the current research will try to adopt the decoy-state BB84 model and analyze the system behavior under realistic quantum noise scenarios. So, the proposed approach, a standard BB84 protocol, will first be formulated and then further enhanced with decoy-state pulse generation to handle the vulnerabilities due to multi-photon pulses. Models like depolarizing noise, amplitude damping, and measurement errors will be used as real-world quantum channels. The model performance will be measured in terms of various performance metrics such as Key agreement ratio, Quantum Bit Error rate, and secure key rate for different qubit lengths. Scalability analysis and validation based on IBM quantum hardware will also be performed in order to measure the impact of real-world device noise on the reliability of generated keys.
Quantum Key Distribution (QKD) is a cryptographic solution that leverages the properties of quantum mechanics to be resistant and secure even against an attacker with unlimited computational power. Satellite-based links are important in QKD because they can reach distances that the best fiber systems cannot. However, links between satellites in low Earth orbit and ground stations have a duration of only a few minutes, resulting in the generation of a small amount of secure keys. In this context, we investigate the optimization of the information reconciliation step of the QKD postprocessing in order to generate as much secure key as possible. As a first step, we build an accurate model of the downlink signal and Quantum Bit Error Rate (QBER) during a complete satellite pass, which are time-varying due to three effects: 1 the varying link geometry over time; 2) the scintillation effect; and 3) the different signal intensities adopted in the Decoy-State protocol. Leveraging the a priori information on the instantaneous QBER, we improve the efficiency of information reconciliation (i.e., the error correction phase) in the Decoy-State BB84 protocol, resulting in a secure key that is almost 3% longer for realistic scenarios, with no computational or hardware complexity overhead.