Underwater wireless communication is rapidly advancing, finding applications in diverse fields such as oceanography, defense, and commercial ventures. However, ensuring security in such transmissions is crucial due to the sensitive nature of the data involved and the challenges posed by the underwater environment. While classical encryption techniques provide some level of security, the emergence of quantum computing presents opportunities and challenges. Quantum key distribution (QKD) offers theoretically unbreakable encryption, making it an attractive solution. Extending QKD capabilities to underwater environments is a significant endeavor in this context. This paper explores the feasibility of applying an entanglement-based non-coherent QKD protocol inspired by the BBM92 protocol to underwater visible light communication (VLC)/QKD systems. We investigate the system’s design criteria and analyze its secret key performance, addressing challenges such as water absorption and turbulence-induced fading, focusing on addressing unauthorized receiver attacks. Through analysis and the considered case study, the feasibility and efficacy of this approach are explored, contributing to the advancement of secure underwater communications.
Underwater wireless communication is rapidly advancing, finding applications in diverse fields such as oceanography, defense, and commercial ventures. However, ensuring security in such transmissions is crucial due to the sensitive nature of the data involved and the challenges posed by the underwater environment. While classical encryption techniques provide some level of security, the emergence of quantum computing presents opportunities and challenges. Quantum key distribution (QKD) offers theoretically unbreakable encryption, making it an attractive solution. Extending QKD capabilities to underwater environments is a significant endeavor in this context. This paper explores the feasibility of applying an entanglement-based non-coherent QKD protocol inspired by the BBM92 protocol to underwater visible light communication (VLC)/QKD systems. We investigate the system’s design criteria and analyze its secret key performance, addressing challenges such as water absorption and turbulence-induced fading, focusing on addressing unauthorized receiver attacks. Through analysis and the considered case study, the feasibility and efficacy of this approach are explored, contributing to the advancement of secure underwater communications.
Underwater optical channels pose significant challenges to the security and reliability of quantum communication systems due to absorption and scattering. In this paper, we investigate the BBM92 entanglement-based quantum key distribution (QKD) protocol under realistic underwater channel conditions. Photon pairs are prepared in non-maximally entangled states, and the underwater propagation medium is modeled as a quantum channel incorporating both amplitude-damping and depolarizing effects, described within the Kraus operator formalism. The protocol performance is evaluated in terms of quantum bit error rate (QBER) and secret key rate (SKR), analyzed as functions of the entanglement degree and channel degradation parameters. Closed-form analytical expressions for the QBER and SKR are derived for the proposed channel model and validated through Monte Carlo simulations. The proposed framework is then applied to various realistic underwater scenarios, considering different water types, namely clear ocean, coastal, and turbid water, as well as varying atmospheric conditions.
The growing importance of Underwater Networks (UNs) in mission-critical activities at sea enforces the need for secure Underwater Communications (UCs). Classical encryption techniques can be used to achieve secure data exchange in UNs. However, the advent of Quantum Computing will pose threats to classical cryptography, thus challenging also UCs. Currently, underwater crypto-systems mostly adopt symmetric ciphers, which are considered computationally quantum-robust, but pose the challenge of distributing the secret key upfront. Post-Quantum Public-Key (PQPK) protocols promise to overcome the key distribution problem. The security of PQPK protocols, however, only relies on the assumed computational complexity of some underlying mathematical problems. Moreover, the use of resource hungry PQPK algorithms in resource-constrained environments such as UNs can require non-trivial hardware/software optimization efforts. An alternative approach is underwater Quantum Key Distribution (QKD), which promises unconditional security built upon the physical principles of Quantum Mechanics. This tutorial provides a basic introduction to free-space Underwater QKD (UQKD). At first, the basic concepts of QKD are presented, based on a fully worked out QKD example. A thorough state-of-the-art analysis of UQKD is carried out. The paper subsequently provides a theoretical analysis of the QKD performance through free-space underwater channels, and its dependence on the key optical parameters of the system and seawater. Finally, open challenges, points of strength and perspectives of UQKD are identified and discussed.
The growing importance of Underwater Networks (UNs) in mission-critical activities at sea enforces the need for secure Underwater Communications (UCs). Classical encryption techniques can be used to achieve secure data exchange in UNs. However, the advent of Quantum Computing will pose threats to classical cryptography, thus challenging also UCs. Currently, underwater crypto-systems mostly adopt symmetric ciphers, which are considered computationally quantum-robust, but pose the challenge of distributing the secret key upfront. Post-Quantum Public-Key (PQPK) protocols promise to overcome the key distribution problem. The security of PQPK protocols, however, only relies on the assumed computational complexity of some underlying mathematical problems. Moreover, the use of resource hungry PQPK algorithms in resource-constrained environments such as UNs can require non-trivial hardware/software optimization efforts. An alternative approach is underwater Quantum Key Distribution (QKD), which promises unconditional security built upon the physical principles of Quantum Mechanics. This tutorial provides a basic introduction to free-space Underwater QKD (UQKD). At first, the basic concepts of QKD are presented, based on a fully worked out QKD example. A thorough state-of-the-art analysis of UQKD is carried out. The paper subsequently provides a theoretical analysis of the QKD performance through free-space underwater channels, and its dependence on the key optical parameters of the system and seawater. Finally, open challenges, points of strength and perspectives of UQKD are identified and discussed.
The growing importance of Underwater Networks (UNs) in mission-critical activities at sea enforces the need for secure Underwater Communications (UCs). Classical encryption techniques can be used to achieve secure data exchange in UNs. However, the advent of Quantum Computing will pose threats to classical cryptography, thus challenging also UCs. Currently, underwater crypto-systems mostly adopt symmetric ciphers, which are considered computationally quantum-robust, but pose the challenge of distributing the secret key upfront. Post-Quantum Public-Key (PQPK) protocols promise to overcome the key distribution problem. The security of PQPK protocols, however, only relies on the assumed computational complexity of some underlying mathematical problems. Moreover, the use of resource hungry PQPK algorithms in resource-constrained environments such as UNs can require non-trivial hardware/software optimization efforts. An alternative approach is underwater Quantum Key Distribution (QKD), which promises unconditional security built upon the physical principles of Quantum Mechanics. This tutorial provides a basic introduction to free-space Underwater QKD (UQKD). At first, the basic concepts of QKD are presented, based on a fully worked out QKD example. A thorough state-of-the-art analysis of UQKD is carried out. The paper subsequently provides a theoretical analysis of the QKD performance through free-space underwater channels, and its dependence on the key optical parameters of the system and seawater. Finally, open challenges, points of strength and perspectives of UQKD are identified and discussed.
In this work we study the underwater optical channel, making a feasibility analysis on the development of a high-speed communication system with security guaranteed by Quantum Key Distribution (QKD) protocol. In particular, we introduce a new model for the attenuation of the underwater medium which includes the effect of turbulence within the marine environment.We report the performance of the system focusing on the most important figures of merit, such as the secret key rate of the quantum channel and the bit rate of the classical channel at the physical layer as a function of the total link range. We carried out these analyses depending on various environmental conditions, such as the geographical area, depth, path-loss and turbulence models. The communication protocols considered are the BB84 with time-bin encoding for QKD and baseband On-Off Keying (OOK) modulation for classical data communication for a maximum link range of 100 meters.
The growing importance of underwater networks (UNs) in mission-critical activities at sea enforces the need for secure underwater communications (UCs). Classical encryption techniques can be used to achieve secure data exchange in UNs. However, the advent of quantum computing will pose threats to classical cryptography, thus challenging UCs. Currently, underwater cryptosystems mostly adopt symmetric ciphers, which are considered computationally quantum robust but pose the challenge of distributing the secret key upfront. Post-quantum public-key (PQPK) protocols promise to overcome the key distribution problem. The security of PQPK protocols, however, only relies on the assumed computational complexity of some underlying mathematical problems. Moreover, the use of resource-hungry PQPK algorithms in resource-constrained environments such as UNs can require nontrivial hardware/software optimization efforts. An alternative approach is underwater quantum key distribution (QKD), which promises unconditional security built upon the physical principles of quantum mechanics (QM). This tutorial provides a basic introduction to free-space underwater QKD (UQKD). At first, the basic concepts of QKD are presented, based on a fully worked out QKD example. A thorough state-of-the-art analysis of UQKD is carried out. The paper subsequently provides a theoretical analysis of the QKD performance through free-space underwater channels and its dependence on the key optical parameters of the system and seawater. Finally, open challenges, points of strength, and perspectives of UQKD are identified and discussed.