We study the significance of the common trusted relay assumption in quantum networks. While most practical implementations of quantum networks rely on trusted devices, the question of security without this assumption has been rarely addressed. Device independent security attempts to minimize the assumptions made on the quantum hardware, entanglement based methods try to avoid relays to the extent possible, and multipath transmission improves robustness and security by enforcing the attacker to conquer more than just a single intermediate node. Common to all these past studies is their focus on the physical layer and direct connections. We describe an attack from the networking and routing layer. Assuming at least one node that is not perfectly tamper-proof, meaning that an attacker has established a foothold to read traffic from the inside, we show how to exploit the eavesdropping detection mechanisms of the quantum key distribution (QKD) devices to cause traffic redirection over the vulnerable node, thus defeating security under the trusted node assumption. We experimentally demonstrate how the attack works on networks of different size and topology, and thereby further substantiate the significance of the trust assumptions for end-to-end security of QKD networks.

Every attempt to access to the Internet through a Web browser, email sent, VPN connection, VoIP call, instant message or other use of telecommunications systems involves cryptographic techniques. The most commonly applied technique is asymmetric cryptography, which is generally executed in the background without the user even being aware. It establishes a cryptographic code based on the computational complexity of mathematical problems. However, this type of cryptography, which is widely used in today’s telecommunications systems, is under threat as electronics and computing rapidly develop. The development of fifth-generation cellular networks (5G) is gaining momentum, and given its wide field of application, security requires special attention. This is especially true faced with the development of quantum computers. One solution to this security challenge is to use more advanced techniques to establish cryptographic keys that are not susceptible to attack. An essential part of quantum cryptography, Quantum Key Distribution (QKD) uses the principles of quantum physics to establish and distribute symmetric cryptographic keys between two geographically distant users. QKD establishes information-theoretically secure cryptographic keys that are resistant to eavesdropping when they are created. In this paper, we survey the security challenges and approaches in 5G networks concerning network protocols, interfaces and management organizations. We begin by examining the fundamentals of QKD and discuss the creation of QKD networks and their applications. We then outline QKD network architecture and its components and standards, following with a summary of QKD and post-quantum key distribution techniques and approaches for its integration into existing security frameworks such as VPNs (IPsec and MACsec). We also discuss the requirements, architecture and methods for implementing the FPGA-based encryptors needed to execute cryptographic algorithms with security keys. We discuss the performance and technologies of post-quantum cryptography, and finally, examine reported 5G demonstrations which have used quantum technologies, highlighting future research directions.

Quantum key distribution (QKD) is a secure communication technique which uses quantum mechanics to protect communications. To overcome large distances, it requires the use of quantum repeaters, which are still challenging nevertheless feasible, or Twin-Field-QKD (TF-QKD) technology, which has been demonstrated several years ago. As it develops and matures, quantum technology is expected to play an increasingly major role in networks. Satellite QKD enables secure communication between devices via both satellites and ground stations. The study explores the transmission of quantum encryption technology in space and presents an overview of cubesats and satellites that currently use quantum key distribution (QKD) technology.

The paper deals with a proposal and implementation of the quantum key distribution in the 5G campus network. The authors share here their practical experience with the implementation of quantum cryptography in 5G which has been achieved within projects the NATO QUANTUM5 and the Czech Ministry of Interior NeSPoQ, both project contributing to the security of 5G mobile networks. Finally, the results of the experimental research demonstrate how the network performance is affected by the use of QKD.

In the current era of mobile communications and next-generation networks, mobility analysis has a key role in guaranteeing the quality of service/experience in the available services. Although a vast amount of work has analyzed mobility from both analytic and stochastic points of view, much of it has focused on a time-based analysis and disregarded spectral features. In this article, we propose a method of analyzing the main features of mobility traces in the frequency domain and determining the possible relationships between typical mobility grades (in terms of average and maximum speed) and the required sampling frequencies. The collection and storage of mobility pattern samples when they are not required is impractical, and therefore, we attempt to demonstrate how mobility can be sampled to avoid information loss or oversampling (many works in the literature are based on a default sampling period of 1 s). The work also contributes with the proposal of a closed form for relating the sampling period and average moving speed with the spectral components. We conducted numerous simulations to confirm that, compared with classical sampling approaches that provide static behavior, it is possible to obtain a gain of about 35%–65% in the collected samples, with a negligible loss of accuracy in the reconstructed signal.

Quantum cryptography can provide a very high level of data security. However, a big challenge of this technique is errors in quantum channels. Therefore, error correction methods must be applied in real implementations. An example is error correction based on artificial neural networks. This paper considers the practical aspects of this recently proposed method and analyzes elements which influence security and efficiency. The synchronization process based on mutual learning processes is analyzed in detail. The results allowed us to determine the impact of various parameters. Additionally, the paper describes the recommended number of iterations for different structures of artificial neural networks and various error rates. All this aims to support users in choosing a suitable configuration of neural networks used to correct errors in a secure and efficient way.

: QKD integration into traditional telecommunication networks is anticipated in the upcoming decades in order to maintain adequate levels of communication security. QKD establishes ITS (Information-Theoretic secure) symmetric keys between the two parties, which they may use to sustain secure flow of data even in the post-quantum era. Since QKD-keys are a valuable and scarce resource, they must be carefully maintained. This paper investigates DoS attacks on actual QKD equipment, in which an adversary with access to QKD services depletes the reserves of QKD-keys maintained at the KMS system. As a result, safety precautions are proposed in order to prevent this scenario and maintain operational QKD service.

: Free Space Optics (FSO) represent a promising technology for secure communications in several types of architectures: from Quantum Key Distribution Networks (QKDNs) to satellite communications. In this paper, in particular, we take into account terrestrial point-to-point laser communications and evaluate the performance in terms of Signal-to-Noise Ratio (SNR) and Bit Error Rate (BER), taking into account different scenarios, that can reflect real situations in which long distances can be reached in a secure way, guaranteeing an acceptable level of BER. So, after a huge campaign of simulations, we would like to let the scientific community know which are the theoretical limits that such kind of communications can reach. We take into account standard telescopes parameters (available today in the market), while configuring several real situations, in function of, for example, bit-rate, visibility, link distance, etc. A brief survey of the existing works is given, then a clearer performance evaluation of terrestrial FSO links is proposed.

Aside from significant advancements in the development of optical and quantum components, the performance of practical quantum key distribution systems is largely determined by the type and settings of the error key reconciliation procedure. It is realized through public channel and it dominates the communication complexity of the quantum key distribution process. The practical utilization significantly depends on the computational capacities that are of great importance in satellite-oriented quantum communications. Here we present SarDub19 error key estimation and reconciliation protocol that improves performances of practical quantum systems.

Mobility is a key aspect of modern networking systems. To determine how to better manage the available resources, many architectures aim to a priori know the future positions of mobile nodes. This can be determined, for example, from mobile sensors in a smart city environment or wearable devices carried by pedestrians. If we consider infrastructure networks, frequently changing the coverage cell may lead to service disruptions if a predictive approach is not deployed in the system. All predictive systems are based on the storage of old mobility samples to adequately train the model. Our focus is based on the possibility to determine an approach for adaptively sampling mobility patterns based on the intrinsic features of the human/node behavior. Several works in the literature examine mobility prediction mobile networks, but all of them are dedicated to the study of time features in mobility traces: none took into account the spectral content of historical mobility patterns for predictive purposes. In contrast, we take into account this spectral content in mobility samples. Through a set of wavelet transforms, we adapted the sampling frequency dynamically and obtained a considerable set of advantages (space, energy, accuracy, etc.). In fact, this issue covers an important role in the IoT paradigm, where energy consumption is one of the main variables requiring optimization (frequent and unnecessary mobility samplings can disrupt battery life). We performed several simulations using real-world traces to confirm the merit of our proposal.

The article presents a series of measurements conducted on the fully-operated Quantum Key Distribution system. These measurements primarily focus on the Quantum Bit Error Rate (QBER), which is the most important parameter of the quantum channel. This parameter was observed and measured for 16 days under the quantum channel’s operating conditions to determine any correlations between the QBER and other quantum link parameters, such as secret key rate. A thorough statistical analysis of the measured data was performed as a part of this investigation and is presented in the paper.