One-time-pad (OTP) can provide unconditionally secure communications between devices with limited resources, but requires continuous key distribution. Existing quantum key distribution (QKD) protocols produce a continuous secret key stream, but cannot be deployed at the devices that have no quantum channels. In this paper, we first propose a scheme, called synchronized random measurement (SRM) to improve the secret key rate of a QKD protocol. Then, we further propose the novel idea of using unmanned aerial vehicles (UAV) as a physical courier to carrier secret key bits generated through QKD at a gateway to all control devices within coverage area of the gateway. When the UAV does not visit a control device to replenish its consumed secret key bits before the bits are depleted, the device suffers from key deficiency and secure communications are interrupted. We formulate an optimization to minimize the number of UAVs needed to cover all control devices, taking into account the limited battery capacity on-board UAVs and the key deficiency requirement. Through simulations, we have confirmed the key quality and rate improvement of the proposed SRM. We have also evaluated the proposed optimization in finding the minimum number of UAVs to cover different numbers of control devices within a gateway coverage area of different sizes. Increasing the coverage area diameter beyond the UAV flight range may require as many UAVs as the number of control devices for a complete service.
One-time-pad (OTP) can provide unconditionally secure communications between devices with limited resources, but requires continuous key distribution. Existing quantum key distribution (QKD) protocols produce a continuous secret key stream, but cannot be deployed at the devices that have no quantum channels. In this paper, we first propose a scheme, called synchronized random measurement (SRM) to improve the secret key rate of a QKD protocol. Then, we further propose the novel idea of using unmanned aerial vehicles (UAV) as a physical courier to carrier secret key bits generated through QKD at a gateway to all control devices within coverage area of the gateway. When the UAV does not visit a control device to replenish its consumed secret key bits before the bits are depleted, the device suffers from key deficiency and secure communications are interrupted. We formulate an optimization to minimize the number of UAVs needed to cover all control devices, taking into account the limited battery capacity on-board UAVs and the key deficiency requirement. Through simulations, we have confirmed the key quality and rate improvement of the proposed SRM. We have also evaluated the proposed optimization in finding the minimum number of UAVs to cover different numbers of control devices within a gateway coverage area of different sizes. Increasing the coverage area diameter beyond the UAV flight range may require as many UAVs as the number of control devices for a complete service.
Unmanned aerial vehicles (UAVs) enable rapidly deployable secure communication, while quantum key distribution (QKD) ensures information-theoretic security over free-space optical channels. In UAV-assisted QKD, however, atmospheric turbulence and mobility-induced misalignment introduce stochastic channel fluctuations that cause intermittent secrecy degradation. Existing trajectory optimization methods are largely deterministic or risk-neutral and fail to address rare but severe deep-fading events. We develop a risk-sensitive stochastic control framework for robust UAV-assisted free-space QKD under atmospheric uncertainty. The UAV motion is modeled as a continuous-time stochastic dynamical system, and the quantum channel transmissivity is characterized by mobility-dependent log-normal fading, yielding a stochastic secret key rate process. The exponential performance functional simultaneously penalizes the propulsion energy and secrecy outage, resulting in a nonlinear risk-sensitive Hamilton-Jacobi-Bellman equation. Simulation results show that there is a significant reduction in secrecy outage probability and key rate variation when atmospheric turbulence exists, but there is only a relatively minor rise in the energy consumption for propulsion, achieving a robustness-efficiency tradeoff for secure aerial quantum communication.
Maritime communication systems face critical challenges in ensuring secure, reliable, and long-range connectivity due to inherent vulnerabilities in traditional encryption, coverage gaps in remote sea areas, and susceptibility to eavesdropping under complex maritime conditions. While Unmanned Aerial Vehicle (UAV)-assisted networks have expanded coverage, security remains a persistent concern. Quantum communication, leveraging quantum key distribution (QKD), offers a paradigm shift by ensuring information-theoretic security. This paper proposes a UAV-based quantum relay maritime communication system that integrates QKD, UAV relays, and satellite networks to establish a hybrid quantum-classical architecture. The innovation lies in deploying UAVs as dynamic relay nodes to enable BB84-protocol-based QKD, while satellites ensure global coverage. Key advancements include: (1) a unidirectional quantum channel design featuring UAV-mounted quantum emitters (Alice) and ship-based receivers (Bob), minimizing technical complexity while ensuring secure key distribution; (2) a multi-layered network integrating ship-UAV-ship, ship-UAV-base station, and ship-satellite communication modes, enhancing resilience against environmental interference; and (3) real-time quantum-classical synergy, where classical data channels (e.g., AES-encrypted) are dynamically secured by QKD-generated keys, achieving compatibility with existing infrastructure while eliminating key leakage risks. Simulations validate the system’s resilience under maritime conditions: optimizing parameters such as detection efficiency (eff > 90%) and dark count (dc < 10⁻⁶/pulse) achieves a stable secure key rate over 100 km, with a Quantum Bit Error Rate (QBER) below 0.5% at 200 km. The proposed architecture offers transformative applications in maritime safety, emergency response, and offshore operations, providing eavesdropping-resistant links for remote vessels and secure data exchange for critical infrastructure. By bridging the gap between quantum security and practical maritime deployment, this work establishes a scalable blueprint for next-generation communication systems in military, commercial, and environmental monitoring domains.
Quantum cryptography is a promising technology that achieves unconditional security, which is essential to a wide range of sensitive applications. In contrast to optical fiber, the free-space optical (FSO) link is efficiently used as a quantum channel without affecting the polarization of transmitted photons. However, the FSO link has several impairments, such as atmospheric turbulence and pointing errors, which affect the performance of the quantum channel. This paper proposes a quantum key distribution (QKD) scheme that uses a time-bin entanglement protocol over the FSO channel that suffers from various channel impairments. Due to the interest in unmanned aerial vehicles (UAVs) and their usefulness for many social, internet-of-things (IoT), civil, and military applications, the proposed QKD-FSO system is integrated with the ground-to-UAV platform. Furthermore, variances in the position and orientation of the UAV are investigated using a tracking system. These variances are considered when evaluating the overall performance of the proposed integrated system. For this purpose, closed-form expressions are obtained for the system average symbol error rate (ASER) and outage probability. The Monte Carlo simulation is used to verify the validity of the proposed expressions. The system security is investigated assuming photon number splitting (PNS) attack. Moreover, the transmit power, time-bin number, and modulation order are optimized to maximize the raw and secret key rates. The results show that for 500 m link, ASER22 mrad and signal-to-noise ratio > 7.5 dB which leads SNRth < 2.5 dB and raw key rate maximized by adjusting the number of time bins according to the received SNR.
Secure communication is vital for unmanned aerial vehicle (UAV) operations, where ensuring data integrity and secrecy is essential. The distinctive challenges in UAV communication UAV communication and the evolving quantum computing field heighten the vulnerabilities of traditional cryptographic methods. Quantum cryptography quantum cryptography offers a promising solution by leveraging quantum mechanics to establish provably secure channels. This chapter provides a comprehensive overview of quantum cryptography quantum cryptography in UAV communications, covering fundamental concepts of quantum mechanics relevant to cryptography. It explores protocols like quantum key distribution (QKD QKD ), quantum secure direct communication (QSDC), and quantum teleportation, quantum teleportation discussing their applicability and limitations in UAV networks. Additionally, the chapter discusses how quantum communication can be effectively utilized for long-range UAV communication. Furthermore, it delves into implementing quantum cryptography-as-a-service for UAVs, presenting real-world case studies and outlining future directions and challenges. Serving as a roadmap for integrating quantum cryptography, this chapter ensures robust security in UAV operations against evolving threats.
This letter investigates a continuous-variable quantum key distribution (CV-QKD) protocol based on Gaussian-modulated coherent states over unmanned aerial vehicle (UAV)-based free-space optical (FSO) links. A realistic fading channel model is developed, including atmospheric turbulence, extinction, and UAV-induced pointing errors. We perform distance-dependent modulation variance optimization to maximize the secret key rate (SKR) under three scenarios: asymptotic, finite-block size (FBS), and FBS with adaptive optics (AO), based on numerical simulations incorporating a realistic UAV-FSO channel model. The results show that finite-size effects reduce the secure transmission range to ~800 m, while AO extends it to ~930 m. Furthermore, optimal modulation improves key rates by up to 40% compared to fixed modulation. This is the first work to jointly model UAV-FSO channel fluctuations, optimize modulation, and quantify finite-size security with AO, confirming the feasibility of CV-QKD for UAV-based communications.
We present a theoretical framework for quantum key distribution (QKD) using orbital angular momentum (OAM) encoded BB84 on an unmanned aerial vehicle (UAV) platform. A unified channel model captures Kolmogorov turbulence, pointing induced misalignment, and finite aperture clipping, enabling quantitative predictions of inter mode crosstalk and the resulting quantum bit error rate (QBER). Using a weak plus vacuum decoy state formulation, we derive composable finite key lower bounds on the secret key rate that incorporate statistical fluctuations, detector dark counts, efficiency mismatch, and error correction leakage. To stabilize performance under non stationary flight conditions, we introduce a lightweight physics informed learning module that combines physical priors with measured link statistics to classify valid pulses, reject corrupted data, and recommend decoding strategies. We outline a complete evaluation pipeline including UAV system architecture, turbulence driven QBER maps, decoy optimization, finite key scaling, and AI calibration metrics. Simulations indicate that under moderate turbulence and milliradian level pointing jitter, the proposed AI assisted method can improve the secret key rate by 10 percent to 30 percent while preserving composable security.