Development of Enhanced Security Techniques for Securing Satellite Communication Using Advanced Cybersecurity Protocols

In this paper, we introduce the Kirchhoff-Law-Johnson-Noise (KLJN) as an approach to securing satellite communications. KLJN has the potential to revolutionize satellite communication security through its combination of simplicity, cost-effectiveness, and resilience with unconditional security. Unlike quantum key distribution (QKD), which requires complex, fragile, and expensive infrastructure like photon detectors and dedicated optical links, KLJN operates using standard electronic components and wires, significantly reducing implementation costs and logistical hurdles. KLJN’s security, grounded in the fundamental laws of classical physics, is impervious to environmental and radiation-induced noise, making it highly reliable in the harsh conditions of satellite communications. This robustness, coupled with its ability to integrate seamlessly with existing infrastructure, positions KLJN as a revolutionary alternative to quantum solutions for ensuring secure, resilient satellite communications. The authors explore the value of achieving unconditionally secure communications in strategic ground-to-satellite networks which address vulnerabilities posed by advanced computational threats, including quantum computing. Our team has examined two leading approaches to unconditional security — the KLJN scheme and QKD — and analyzed the potential use of each for space systems. While QKD leverages quantum mechanics for security, it faces challenges related to cost, complexity, and environmental sensitivity. In contrast, the KLJN scheme utilizes classical physics principles to provide a simpler, more cost-effective, and resilient alternative, particularly for ground-based systems. Further, this paper highlights the potential for complementary roles of these technologies in hybrid networks: KLJN can facilitate secure key exchanges without QKD for ground communications connected via wire, and QKD could facilitate secure inter-island and direct-to-satellite communications. Through a detailed analysis of implementation challenges, key exchange speeds, and network architectures, this study concludes that KLJN offers significant advantages in simplicity, cost-efficiency, and robustness, making it a practical choice for many secure communication applications.

In recent years, quantum-based techniques have attracted significant research attention because of its unique advantages on satellite communications, especially for security problem. Security guarantee is one of the most important requirements in QoS-driven 3D satellite networks. Quantum key distribution (QKD) is a methodology for generating and distributing random encryption keys using the principles of quantum physics, which enables two distant communications parties to securely communicate in a way that cannot be eavesdropped on without being detected. Although the QKD method can ensure the absolute security transmission over 3D satellite networks, it imposes many new implementation challenges due to the various limitations on quantum communication over long distances via 3D free space, including quantum channel attenuation, photon-state disruption and vulnerability to noise/interference, laser-beam widening, and constrained security-key generation rate. These problems get even more challenging when QoS provisioning is required for the applications over the 3D satellite networks. To overcome the aforementioned difficulties, we propose the framework to efficiently implement the QKD for security guarantees over quantum-repeater-based QoS-driven 3D satellite networks. First, we develop the quantum-repeater-based QKD satellite network architecture. Then, we design the quantum repeater including the purification scheduling algorithm and the optimal QoS-based repeating-router selection scheme in quantum-repeater-based QKD satellite networks. Finally, the obtained simulations evaluation validate and evaluate our proposed algorithms and schemes.

There has been a dramatic increase in the number of Internet of Things (IoT) devices and their applications. Furthermore, there is a growing impetus to integrate IoT networks on a global scale, using satellites to expand the range of IoT connectivity into geographically remote areas. Ensuring the security of satellite backhaul for IoT networks is thus of paramount importance. The steady advance of quantum computing in recent years threatens to nullify classical cryptographic approaches based on assumptions of computational hardness, motivating the need for post-quantum cryptography. Quantum computing algorithms have been developed that, once a quantum computer of sufficient scale is realised, will be able to break classical cryptosystems efficiently (at polynomial-time complexity). A promising method of securing information against this threat at the physical layer has emerged in the form of quantum key distribution (QKD). QKD exploits the fundamental physical properties of light to guarantee information-theoretic security. Research into the application and standardisation of QKD to secure satellite backhaul, however, is still in its infancy. This paper presents a brief overview of the theoretical basis for QKD, whilst also providing a survey of contemporary QKD protocols. It evaluates the ability of these protocols to secure satellite backhaul in the context of a typical satellite-IoT network architecture. Furthermore, it highlights the vulnerabilities, as well as the technical challenges associated with this endeavour. Finally, it proposes directions for future research and development into protocols and standardisation for the satellite-integrated IoT domain. Several challenges must be overcome before QKD can evolve into a global-scale solution for securing satellite-IoT. Secret key generation rate remains very low in practical demonstrations of trusted-relay QKD satellite architectures. Further research is needed to overcome or mitigate the fundamental rate-distance trade-off before satellite QKD can be considered practicable in an IoT application. Alternatives that do not rely on trusted nodes are contingent on nascent technologies such as quantum repeaters and quantum memory. Whilst in theory QKD provides perfect information-theoretic security, it remains vulnerable to attacks that exploit imperfections in real-world equipment. Further effort is needed to develop QKD protocols that can safeguard against the aforementioned challenges.

It is well known that optical access networks are able to provide high data rates over long distances and to a reasonable number of users. Security and privacy are always a challenge for public accessible network infrastructures. Especially in time-division multiplexing passive optical networks (TDM-PONs), in which the downstream signal is broadcasted to all users connected via the same wavelength channel in a shared fiber link, privacy can be a critical concern. Although encryption at the application layer can provide a high level of security, this can be achieved only if the encryption key distribution is perfectly save. On the other hand, encryption on the physical layer such as quantum cryptography or, more precisely, quantum key distribution (QKD) is a very promising approach to achieve secure communication. However, there remain several issues that have to be solved before the quantum cryptography reaches the maturity level needed for a cost effective implementation in practical networks. In this paper, we address quantum key distribution (QKD) over passive optical access networks, which is an enabling technology required to cost efficiently deploy practical quantum encrypted data communication in the access area. We study different methods to integrate QKD systems in conventional optical access networks and quantitatively evaluate their suitability for a potential implementation.

Security of data transported in telecommunication networks is of primary importance for internet service providers (ISP) as data safety is at the basis of the mutual trust with customers. People were looking for theoretically secure transmission techniques since a long-time to ensure long-term confidentiality of data flows exchanged on these networks. Besides advanced encryption algorithms and the recently proposed post-quantum cryptography (PQC), a physics-based technology using quantum key distribution (QKD) was proposed a long time ago to approach this objective. QKD recently gained a renewed interest with many research programs worldwide supported by public authorities, and some pre-industrial QKD systems delivered to the market. However, some constraints of optical transport networks make sometimes complicated the deployment of such QKD systems in the field, such as the need of a dedicated fiber infrastructure for QKD, or the impossibility for a quantum key to pass through an optical amplifier. In this paper, we report the transmission of a coherent 400-Gbps dual-polarization 16QAM channel that transports QKD-secured 100-GbEthernet data stream with other fifty-four WDM channels at 100-Gbps over 184-km of standard single mode fiber (SSMF) through three QKD links (of 66-km, 50-km and 66-km, respectively) and two trusted nodes. On the two longest sections of the link, the quantum key and WDM signals are propagated on two different fibers, while on the shortest section of 50-km the QKD signal and WDM comb co-propagate on a same fiber. Secret key rates (SKR) and quantum bit error rate (QBER) are measured and reported on each of the three fiber sections. Various analyses are carried out on the co-propagation section of 50-km: the SKR / QBER sensitivity to the optical power of the WDM comb, or to the optical signal-to-noise ratio (OSNR) of the WDM channels co-propagating with the quantum signal is studied. The unique arrangement of the most advanced QKD and WDM technologies reported here constitutes, in our opinion, a world first, and demonstrates that QKD and WDM solutions can coexist in already deployed optical transport networks.

A robust image transmission scheme deploying distributed-Alamouti space-time code (STC) over wireless relay networks is proposed. Specifically, we propose a cross-layer design combining application, networking, and physical layer to enhance the quality of multimedia data over error-prone wireless channels. At the application layer, a coded image sequence based on the wavelet transform is divided into two priorities. The higher priority contains the most significant information of image and the lower priority conveys less important information. At the physical layer, two pre-assigned relays cooperate to form a distributed-Alamouti code which help the source to transmit the low priority sequence of the image over error-prone wireless channels. At the networking layer, among the whole relay nodes in the networks we select two relay nodes which provides the maximum signal-to-noise ratio to convey the higher priority. With this strategy, we implicitly achieve unequal error protection for image transmission without controlling power or varying modulation and coding at the transmitter at the expense of increasing network's overhead (i.e. feedback information). The selection of relays needs limited feedback, hence, enabling our proposed scheme feasible in practical applications. Analytical and simulation results are provided to verify our proposal. It has been shown that the image quality is remarkably enhanced in terms of objective quality using the proposed scheme compared to the conventional transmission schemes.

This paper presents a novel cross-layer approach to multiuser H.264/AVC video stream transmission over wireless networks. We consider the joint optimization of three layers of the protocol stacks: the application (APP) layer, the media access control (MAC) layer and the physical (PHY) layer. At the APP layer, the contribution of each packet to the perceptual video quality is evaluated by distortion effect of the packet loss, which is estimated by a Packet Relative Importance Index (PRII). At the MAC layer and the PHY layer, the Gilbert-Elliott (GE) model is employed to describe the time-varying nature of the wireless networks. An objective function for cross-layer optimization is developed based on the layered abstracted parameters from the APP layer, the MAC layer and the PHY layer. Our goal is to maximize the perceptual quality of the video transmitted through the wireless network with constraint of the limited resources. Simulation results show that the proposed scheme performs significantly than the conventional scheduling schemes for video transmission.

This thesis presents a set of works on the use of deep learning (DL) in the next generation of communications systems. Digital communications is a cornerstone technology of the modern information age. Thus, a natural question to ask is whether DL enables better solutions for common problems in communications systems. To that end, this thesis poses two research questions: RQ1: How can deep learning techniques be effectively applied across different parts of the networking stack? RQ2: What are the advantages and challenges of implementing deep learning in the physical layer versus the application layer? This thesis consists of two parts with three chapters each. The first three content chapters discuss works that relate to the physical layer of the networking stack. The second three chapters contain works that relate to the application layer of the networking stack. Chapter 2 focuses on improving deep learning in the physical layer of communication networks. We develop a more flexible neural receiver that can handle multiple types of modulations. A modulation type is a configuration that makes a trade-off between speed and reliability. This approach makes deep learning based communication systems modular, making them more adaptable and efficient. Chapter 3 continues work on the physical layer, tackling the challenge of making deep learning receivers faster and more energy-efficient. We use a method of deep learning called group equivariant deep learning to build neural networks that inherently understand certain properties of radio signals. This results in smaller, more efficient networks that perform just as well as larger ones. Chapter 4 shifts to underwater acoustics. We use a technique called contrastive learning to train neural networks without labeled data. This approach could improve underwater sound classification and potentially help simulate underwater communication channels more accurately. Chapter 5 explores a security vulnerability in video streaming platforms like YouTube. Videos are generally streamed dynamically which is known to result in vulnerabilities. Using deep learning techniques, specifically deep-metric learning, we demonstrate that video IDs can be identified from encrypted streams with minimal examples. This work highlights how DL simplifies exploiting vulnerabilities between communication layers. Chapter 6 focuses on improving neural image compression. Building upon the work of Yang et al. (2020), we propose SGA+, a set of functions that improve the weighting of Gumbel probabilities. Our approach, particularly the SSL function with hyperparameter a, converges faster and achieves better PSNR/BPP trade-offs than the original SGA method. This advancement in neural image compression is important for reducing internet congestion and improving edge device capabilities. Chapter 7 investigates the application of Federated Learning (FL) in Face Recognition (FR) to address privacy concerns and issues with data heterogeneity. Given the challenges of non-shared identities across parties, we propose using federated meta-learning. Our approach demonstrates improved overall performance per client, especially under heterogeneous data splits. Notably, the performance gains primarily benefit weaker clients, reducing the variance in performance across clients. Together, these works provide partial answers to the research questions posed above. Major factors in applying DL across network layers are modularity, translating DL research to communications, and integrating DL advancements into the communications stack of tomorrow. Notably, there are differences between the application layer and physical layer. This thesis found the physical layer to benefit more broadly from the inclusion of DL. However, the models used throughout this work were highly similar; they were all based on convolutional neural networks (CNNs). The future of DL for communications looks bright and much work remains to be done.

Guest editorial IJSCN special issue on 3GPP NTN standards for future satellite communications

Recent advancements in reactor designs could offer new revolutionary capabilities, including remote monitoring, increased flexibility, and reduced operation and maintenance costs. Embracing new digital technologies would allow for operational concepts such as semiautonomous or near-autonomous control, and two-way communications for real-time integration with the upcoming smart electric grid. However, such continuous data transmission from and toward a reactor site could potentially introduce new challenges and vulnerabilities, necessitating the prioritization of cybersecurity. Conventional information technology–based encryption schemes, which rely mostly on computational complexity, have been shown to be vulnerable to cyberattacks. With the advent of quantum computing, practically any asymmetric encryption could be potentially compromised. For example, it has been shown that a RSA-2048 bit key could be broken in 8 h. To address this challenge, we explore the feasibility of quantum key distribution (QKD) to secure communications. QKD is a physical layer security scheme relying on the laws of quantum mechanics instead of mathematical complexity. QKD promises not only unconditional security but also detection of potential intrusion, as it allows the communication parties to become aware of eavesdropping. To test the proposed hypothesis, a novel simulation tool (NuQKD) was developed to allow for real-time simulation of the BB84 QKD protocol between two remote terminals. A reference scenario is proposed, generic enough to cover various internal and external communication links to a reactor site. Using NuQKD, the internal and external data links were modeled, and receiver operating characteristic curves were calculated for various QKD configurations. A performance analysis was conducted, demonstrating that QKD can provide adequate secret key rates with low false alarms and has the potential of addressing the nuclear industry’s high standards of confidentiality for distance lengths up to 75 km of fiberoptics. Using a conservative estimation, QKD can provide up to 21.5 kbps of secret key rate for a distance of 1 km and 14.4 kbps at 10 km. The target secret key rates for the corresponding links were estimated at 16 kbps and 80 bps, respectively, based on the analysis of real data from a PUR-1 fully digital reactor. Consequently, QKD is shown to be compatible with existing and future point-to-point reactor communication architectures. These results motivate further study of quantum communications for nuclear reactors.

The usage of QKD protocols through the current terrestrial infrastructure is limited to a hundred kilometers due to attenuation problems with fiber. This implies that the satellite will be necessary for the transmission of quantum keys in order to avoid these terrestrial limitations. Therefore, the current debate does not lie in the need for the satellite but rather in what type of infrastructure will be best suited, and specifically the usage of GEO vs LEO satellites. This analysis is not trivial and should not consider only the link budgets and the physical layer as it has been done up to date. It should also consider even more important factors, as the service KPIs that the end user will request such as key rate, availability, security of the keys and their maintenance, etc., as well as the possible communications architectures to provide the service. Therefore, the analysis should introduce the market oriented component, and provide the optimal solutions based on the scenarios and requirements requested by the customer. In this frame, and under ESA ARTES funding, a Spanish consortium led by Hispasat is defining an operational GEO QKD mission that shall fly as hosted payload in 2025. The quantum communications payload proposed in this mission represents a step beyond the state of the art since it is the first implementation of a quantum key distribution channel from geostationary orbit. This new service will involve the implementation of a complete communications system not currently available that will require the development of new technological elements and the adaptation for their operation in space of technologies such as photon sources, telescopes for optical communications compatible with quantum state transmission or processors for the distillation of quantum keys, as well as a whole new ground segment to control and manage the new quantum key distribution service and its integration into a future European secure quantum communications network. Details of the challenges and approach of this mission shall be presented

We present a control plane architecture to enable software-addressable optical acceleration from the application layer. The architecture is experimentally examined on a cluster-computing test-bed by enabling physical layer optical multicasting on-demand for the application layer to achieve non-blocking performance.

A weighted fractional Fourier transform (WFRFT) based on channel state information (CSI), aiming to safeguard the physical (PHY) layer security of wireless communication system, is proposed. With the proposed scheme, WFRFT is first applied to satellite communications such that the transmitted signal is distorted and can only be neutralized by inverse‐WFRFT with the same parameter. Moreover, by exploiting the physical properties of wireless channels, the CSI matrix is transformed as a secret key. In addition, by adding phase rotation (PR) factors to each branch of the WFRFT system, a new unitary matrix with the encryption properties is constructed, and hence, the satellite communications secrecy is reliably guaranteed due to the variation in signal characteristics. Finally, the efficacy of the security enhancement is evaluated in terms of the average bit error rate (BER) and the secrecy capacity. Simulation results show that the proposed encryption method can make the detection and demodulation more difficult for the eavesdropper.

Satellite communication is a critical component of global connectivity, enabling data transmission across vast distances for applications such as telecommunications, navigation, and broadcasting. However, signal degradation due to atmospheric interference, scattering, and attenuation presents a significant challenge to maintaining reliable communication. This study explores the role of quantum entanglement in mitigating signal loss and improving encryption in satellite communication systems. By leveraging quantum key distribution (QKD) and quantum error correction techniques, secure and efficient data transmission can be achieved. Various strategies, including adaptive beamforming, higher frequency bands, satellite relays, and real-time atmospheric monitoring, are examined to enhance communication reliability. The integration of quantum communication with advanced signal processing techniques demonstrates potential improvements in data integrity, reduced latency, and enhanced security. Furthermore, the study investigates the impact of deploying higher frequency bands and optimizing transmission through real-time atmospheric monitoring to counteract signal attenuation. The findings highlight the transformative potential of quantum technology in modern satellite networks, offering a pathway to the next generation of secure and efficient communication. While challenges such as atmospheric disturbances and technical complexities remain, continued advancements in quantum technologies and real-time optimization strategies hold promise for overcoming these obstacles. Future research should focus on refining quantum protocols and addressing implementation challenges to fully realize the benefits of quantum entanglement in satellite communication systems.

The advantages offered by fiber-optic systems are summarized., These include low susceptibility to electromagnetic interference, absence of electromagnetic radiation leaks, and absence of noticeable delay in signal propagation. Attention is then given to recent improvements in satellite communications, including delay `compensators' and forward error-correcting codes. Work being done to overcome the problem of modal dispersion in fiber optics is surveyed. The switching advances expected in fiber-optic networks are also described.