Unconditionally Secure, Wireless-Wired Ground–Satellite–Ground Communication Networks Utilizing Classical & Quantum Noise

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 Kirchhoff-law-Johnson-noise (KLJN) scheme is a statistical/physical secure key exchange system based on the laws of classical statistical physics to provide unconditional security. We used the LTSPICE industrial cable and circuit simulator to emulate one of the major active (invasive) attacks, the current injection attack, against the ideal and a practical KLJN system, respectively. We show that two security enhancement techniques, namely, the instantaneous voltage/current comparison method, and a simple privacy amplification scheme, independently and effectively eliminate the information leak and successfully preserve the system’s unconditional security.

The increasing reliance on satellite communication for critical applications, such as navigation, remote sensing, and communication, has made it a prime target for cyber-attacks. The unique characteristics of satellite communication, including its broadcast nature and long signal propagation delays, make it particularly vulnerable to various types of cyber threats. To address these security concerns, this research paper proposes the development of enhanced security techniques for securing satellite communication using advanced cybersecurity protocols. This study begins by investigating the existing security protocols and techniques used in satellite communication, identifying their limitations. It then introduces a novel framework that integrates advanced cybersecurity protocols, such as quantum key distribution (QKD), blockchain, and artificial intelligence (AI), to provide comprehensive end-to-end security for satellite communication. The proposed framework is structured into three layers: the physical layer, the network layer, and the application layer. At the physical layer, quantum key distribution is employed for secure key exchange, ensuring that the encryption keys are transmitted without being intercepted. The network layer utilizes blockchain technology to secure data transmission, providing a decentralized and tamper-proof ledger for transaction and data management. Finally, the application layer leverages artificial intelligence for threat detection and mitigation, enabling real-time identification and response to potential security threats. The proposed framework is rigorously evaluated using simulations and experimental results. These evaluations demonstrate the framework's effectiveness in preventing various types of cyber-attacks, including eavesdropping, jamming, and spoofing. The results show a significant improvement in security compared to existing protocols, with notable reductions in the bit error rate and increases in the signal-to-noise ratio. Overall, the proposed framework offers a robust and efficient solution for enhancing the security of satellite communication systems, addressing the unique challenges posed by the broadcast nature and long signal delays of these systems.

Accelerating QKD post-processing by secure offloading of information reconciliation

Quantum cryptography, and especially quantum key distribution (QKD), is steadily progressing to become a viable tool for cryptographic services. In recent years we have witnessed a dramatic increase in the secure bit rate of QKD, as well as its extension to ever longer fibre- and air-based links and the emergence of metro-scale trusted networks. In the foreseeable future even global-scale communications may be possible using quantum repeaters or Earth–satellite links. A handful of start-ups and some bigger companies are already active in the field. The launch of an initiative to form industrial standards for QKD, under the auspices of the European Telecommunication Standards Institute, described in the paper by Laenger and Lenhart in this Focus Issue, can be taken as a sign of the growing commercial interest.

Relativistic quantum key distribution (QKD) protocol is a kind of modified BB84 QKD protocol based on the principles of not only quantum mechanics but also special relativity. Its advantage compared with BB84 protocol is that all of the qubits could be used for key generation, and Alice and Bob are able to select any measuring bases. We prove its unconditional security against coherent attack via the method based on CSS codes: begin with a modified EPR based protocol which can be proved unconditionally secure, then reduce the protocol to a CSS codes based protocol. Finally, the CSS codes based protocol is demonstrated equivalent to the relativistic QKD protocol, and we arrived at the conclusion of the unconditional security of the final key.

Classical cryptographic systems are increasingly challenged by advances in computing power and new algorithmic techniques, particularly with the rise of quantum computing, which threatens the security of current encryption methods. This has spurred interest in quantum-resistant cryptography, aimed at creating algorithms that can withstand attacks from quantum computers. Traditionally, secure key transport over alternate channels has been a significant challenge, but quantum mechanics offers a solution. Quantum Key Distribution (QKD) is a revolutionary method for secure communication that leverages quantum principles. Unlike traditional methods, QKD provides unconditional security, with key security ensured by the laws of physics rather than computational difficulty. The BB84 protocol, introduced in 1984 by Bennett and Brassard, is a leading QKD scheme known for its simplicity and effectiveness in generating eavesdropping-resistant cryptographic keys. It facilitates secure key transport over alternate channels. This documentation aims to advance QKD security by practically implementing and analyzing the BB84 protocol. Through detailed theoretical analysis, simulation studies, and experimental validation, the practical impacts, and limitations of BB84-based QKD systems are examined. Additionally, a practical implementation of quantum key distribution using a sudoku key demonstrates the process's simplicity and effectiveness. These findings are expected to pave new paths in the field of cryptanalysis in the emerging Quantum Age.

Quantum key distribution (QKD) protocols aim at allowing two parties to generate a secret shared key. While many QKD protocols have been proven unconditionally secure in theory, practical security analyses of experimental QKD implementations typically do not take into account all possible loopholes, and practical devices are still not fully characterized for obtaining tight and realistic key rates. We present a simple method of computing secure key rates for any practical implementation of discrete-variable QKD (which can also apply to measurement-device-independent QKD), initially in the single-qubit lossless regime, and we rigorously prove its unconditional security against any possible attack. We hope our method becomes one of the standard tools used for analysing, benchmarking, and standardizing all practical realizations of QKD.

Unlike from the existing classical protocols, a quantum key distribution (QKD) protocol can help two remote parties do secure private communication with proven security. We study various QKD protocols with special emphasis on security, feasibility and robustness. The security proof of the standard four-state protocol can be done based on the virtual entanglement purification by classical hashing. QKD can be done with unconditional security even when an imperfect source such as the coherent light from a traditional laser device is used. In particular, we show that one can do QKD effectively with a traditional laser device through the decoy-state method, i.e., changing the intensity of each pulse randomly among three values. One can improve the key rate and noise threshold if the channel noise is asymmetric. One can also do QKD more robustly with a two-qubit quantum code given that the channel noise is collective or independent.

Quantum key distribution (QKD) provides the opportunity to deliver unconditional communication security. The most robust version of QKD relies on quantum entanglement. Very recently, ubiquitous deployment of such entanglement-based QKD over large distances has moved closer to reality, as verified by quantum entanglement distribution from a low Earth orbit satellite. We will demonstrate that this robust form of QKD via space will require a renewed focus on short-block length error-correcting codes in order to facilitate the reconciliation phase of the key distribution. Focusing on discrete variable QKD and adopting the low data rates consistent with measured entanglement distribution from space, we quantify the benefits of state-of-the-art short- block length codes in the context of device- independent QKD. Our results highlight the trade- off between the attainable key throughput vs the communication latency encountered in space-based implementations of this ultra-secure technology.

The existing unconditional security definitions of quantum key distribution (QKD) do not apply to joint attacks over QKD and the subsequent use of the resulting key. In this paper, we close this potential security gap by using a universal composability theorem for the quantum setting. We first derive a composable security definition for QKD. We then prove that the usual security definition of QKD still implies the composable security definition. Thus, a key produced in any QKD protocol that is unconditionally secure in the usual definition can indeed be safely used, a property of QKD that is hitherto unproven. We propose two other useful sufficient conditions for composability. As a simple application of our result, we show that keys generated by repeated runs of QKD degrade slowly.

Security of modern classical data encryption often relies on computationally hard problems, which can be trivialized with the advent of quantum computers. A potential remedy for this is quantum communication which takes advantage of the laws of quantum physics to provide secure exchange of information. Here, quantum key distribution (QKD) represents a powerful tool, allowing for unconditionally secure quantum communication between remote parties. At the same time, microwave quantum communication is set to play an important role in future quantum networks because of its natural frequency compatibility with superconducting quantum processors and modern near-distance communication standards. To this end, we present an experimental realization of a continuous-variable QKD protocol based on propagating displaced squeezed microwave states. We use superconducting parametric devices for generation and single-shot quadrature detection of these states. We demonstrate unconditional security in our experimental microwave QKD setting. The security performance is shown to be improved by adding finite trusted noise on the preparation side. Our results indicate feasibility of secure microwave quantum communication with the currently available technology in both open-air (up to ~ 80 m) and cryogenic (over 1000 m) conditions.

<sec>Quantum key distribution (QKD) is a pivotal technology in the field of secure communication by using the principles of quantum mechanics to implement theoretically unbreakable encryption. However, QKD faces significant challenges in achieving large-scale deployment. The primary hurdle lies in the scarcity of quantum resources, especially entangled photon pairs, which are fundamental to protocols such as Ekert91. In traditional QKD implementations, only a small potion of the generated entanglement pairs contribute to generating the original key, resulting in lower efficiency and resource waste. Resolving this limitation is crucial to the advancement and scalability of QKD networks.</sec><sec>This paper introduces an innovative approach to QKD by integrating the multiscale entanglement renormalization ansatz (MERA), a technique which is originally developed for many-body quantum systems. By utilizing MERA’s hierarchical structure, the proposed method not only improves the efficiency of entanglement distribution but also reduces the consumption of quantum resources. Specifically, MERA compresses many-body quantum states into lower-dimensional representations, allowing for the transmission and storage of entanglement in a more efficient manner. This compression significantly reduces the number of qubits required, optimizing both entanglement utilization and storage capacity in quantum networks.</sec><sec>To evaluate the performance of this method, we conduct simulations under standardized conditions. In the simulation, a 1024-bit encryption request, an 8% error rate, an average path length of 4 hops in the quantum network, and a 95% success rate for link entanglement generation and entanglement swapping operations are assumed. These parameters reflect the real physical conditions in contemporary QKD networks. The results demonstrate that compared with traditional QKD protocols, the MERA-based approach saves 124151 entangled pairs, which is impressive. This significant reduction in resource consumption indicates the potential application of MERA in improving the efficiency of QKD systems without sacrificing security. Importantly, the security of the key exchange process remains intact, for the method inherently adheres to the principles of quantum mechanics, particularly the no-cloning theorem and the use of randomness in the decompression layer.</sec><sec>Some conclusions can be drawn below. The MERA not only enhances the scalability of QKD by optimizing quantum resource allocation, but also maintains the necessary security guarantees for practical cryptographic applications. By integrating MERA into existing QKD frameworks, we can significantly reduce the resource overhead and make large-scale, secure quantum communication more feasible. These findings contribute a new dimension to the field of quantum cryptography, indicating that advanced quantum many-body techniques like MERA have the potential to unlock the full potential of quantum networks in real world.</sec>

Security is an increasingly growing concern for network communications and video is an emerging segment of network traffic that uses large amounts of bandwidth. Streaming video, vs. downloading a video for later viewing, requires a continuous, high data rate. The data rate will vary depending on the quality of the video. Video surveillance is a streaming video application that in addition may require securing the data stream to prevent others from viewing it as well as prevent any tampering of that video stream. There are two parts to secure communication, key distribution and ciphers. A cipher requires a secret key that is used to encrypt data (plaintext), transforming it into an unreadable form (ciphertext) and then to decrypt it back into its original form. Key distribution is the method used to exchange the secret key between the desired end users and no one else. Current block ciphers are relatively slow compared to existing bandwidth because they require a substantial amount of processing that must compete for CPU cycles with the video encoding and compression processing. Frequently changing keys is thought to increase security, but the public key exchange method requires even more processing than the cipher. Cipher and key exchange processing can be off-loaded from the CPU, when the communication end point is the other end of the link, by using dedicated hardware called a link encryptor. Current classical security algorithms are based on the perceived computational complexity of certain mathematical functions and have not been proved secure. The public key algorithm is at risk from future quantum computers, whereas block ciphers are only weakened and an easy fix is to double the length of the key. Both are constantly at risk from a potential break through algorithm. Communications channels that exploit properties unique to quantum systems have been shown to enable functionality that cannot be achieved by classical means. If a high level of security is deemed necessary for the video stream, one might consider the use of a One-Time-Pad cipher [Wikipedia 2010], the only provably secure cipher, along with Quantum Key Distribution (QKD), also a provably secure method of exchanging the secret keys used by a cipher. QKD is a protocol based on the quantum laws of physics and is provably information theoretically secure to accomplish key distribution [Gisin, et al., 2002]. QKD keys, when used with a One-Time-Pad cipher, can provide secure communications. A One-Time-Pad cipher algorithm performs an Exclusive OR (XOR) on a random secret key and the message. This is a simple operation that incurs little overhead compared to the more common

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.