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This study introduces a novel approach to bolstering quantum key distribution (QKD) security by implementing swift classical channel authentication within the SARG04 and BB84 protocols. We propose mono-authentication, a pioneering paradigm employing quantum-resistant signature algorithms—specifically, CRYSTALS-DILITHIUM and RAINBOW—to authenticate solely at the conclusion of communication. Our numerical analysis comprehensively examines the performance of these algorithms across various block sizes (128, 192, and 256 bits) in both block-based and continuous photon transmission scenarios. Through 100 iterations of simulations, we meticulously assess the impact of noise levels on authentication efficacy. Our results notably highlight CRYSTALS-DILITHIUM's consistent outperformance of RAINBOW, with signature overheads of approximately 0.5% for the QKD-BB84 protocol and 0.4% for the QKD-SARG04 one, when the quantum bit error rate (QBER) is augmented up to 8%. Moreover, our study unveils a correlation between higher security levels and increased authentication times, with CRYSTALS-DILITHIUM maintaining superior efficiency across all key rates up to 10,000 kb/s. These findings underscore the substantial cost and complexity reduction achieved by mono-authentication, particularly in noisy environments, paving the way for more resilient and efficient quantum communication systems. [ABSTRACT FROM AUTHOR]

Passive light-source side channel in quantum key distribution (QKD) provides additional information to an eavesdropper via various non-operational degrees of freedom of the optical signal. The currently known explicit eavesdropping strategies aimed at additional information gain from the passive light-source side channel were limited to the attack on the side channel and the operational degree of freedom separately. As a result, their efficiency is far from being optimal. Here we provide the joint eavesdropping strategy on both operational degree of freedom and the passive light-source side channel of the generic form, and develop a method to calculate the corresponding secret key rate. In particular, we use the optimal phase-covariant cloning of the signal photon state followed by a joint collective measurement of the side channel and the operational degree of freedom. To estimate security under the explicit attack strategy, we develop an "effective error" method and demonstrate it on the BB84 protocol with decoy states. Our work extends the practical analysis of QKD protocols with the light-source side channels and can be used as a tool for the analysis of realistic eavesdropping methods. [ABSTRACT FROM AUTHOR]

In the emerging era of quantum communications, Internet of Things (IoT) devices in high-speed train (HST) environments encounter formidable challenges. These devices are constrained by limited power and computational capabilities while needing to safeguard their data and communications against adversaries equipped with quantum-grade computational power. To counter such threats, Quantum Key Distribution (QKD) emerges as a vital solution, facilitating secure communication between servers and IoT controllers, thereby shielding the more vulnerable IoT sensors. This paper delves into the application of QKD within the unique scenario of HSTs, employing Free Space Optics (FSO) to establish high data rate communication channels. Our experimental setup involves the integration of FSO links for photon exchange essential to QKD. We meticulously explore the QKD process in the context of HSTs, detailing our methodology that involves the alignment of FSO transceivers on ground base stations with those on the moving trains, thereby enabling efficient photon exchange. The study presents quantitative results demonstrating that this approach allows for the exchange of a substantial number of keys, with negligible impact on FSO data throughput. These findings highlight that our proposed method can significantly enhance IoT communication security in HSTs without compromising the Quality of Service (QoS) offered to train passengers. Furthermore, we assess the system’s performance under various visibility conditions, which is crucial for FSO viability. Our results indicate the robustness of the proposed QKD method in diverse operational scenarios, underlining its practical applicability in securing IoT communications within HST environments. Through this study, we provide a comprehensive understanding of implementing QKD in high-speed mobile settings, contributing valuable insights into its effectiveness and feasibility.

Information reconciliation (IR) is a key step in quantum key distribution (QKD). In recent years, blind reconciliation based on low-density parity-check (LDPC) codes has replaced Cascade as a standard de facto since it guarantees efficient IR without a priori quantum bit error rate estimation and with limited interactivity between the parties, which is essential in high key-rate and long-distance QKD links. In this article, a novel blind reconciliation scheme based on rateless protograph LDPC codes is proposed. The rate adaptivity, essential for blind reconciliation, is obtained by progressively splitting LDPC check nodes, which ensures a number of degrees of freedom larger than puncturing in code design. The protograph nature of the LDPC codes allows us to use the same designed codes with a large variety of sifted-key lengths, enabling block length flexibility, which is important in largely varying key-rate link conditions. The code design is based on a new protograph discretized density evolution tool.

The industrial internet of things (IIoT) refers to a system of interconnected equipment, sensors, and devices deployed within industrial environments whose primary function is to collect and facilitate the exchange of data. IIoT has gained significant traction in several domains, encompassing remote monitoring, equipment management, and condition tracking. The utilization of IIoT in different environments gives rise to apprehensions regarding the security of data. As a result of this, it is imperative to ensure that rigorous safety measures are in place to safeguard the confidentiality of the sensitive information being transmitted. The utilization of elliptic curve cryptography (ECC) and quantum key exchange (QKE) in IIoT networks holds promise for achieving robust and predictable security measures. ECC is a widely adopted type of public-key cryptography due to its efficiency and security. It has gained significant popularity in contemporary systems. QKE is an innovative methodology that originates from the fundamental principles of quantum physics. The system has the ability to generate a secret key that is impervious to hacking attempts, as it leverages natural principles instead of conventional mathematical procedures. Due to this characteristic, quantum key distribution (QKD) is widely recognized as one of the most reliable methods for key exchange. The combination has led to the creation of a novel cryptographic model that integrates elliptic curve cryptography (ECC) and quantum key exchange (QKE) techniques for the generation and distribution of cryptographic keys. The model leads to an increase in the base probability of the Bennett–Brassard protocol (BB84) from 0.5 to 1. Subsequently, the keys that are produced are employed for the encryption of data through a streamlined and adapted variant of the Advanced Encryption Standard (AES), thereby expediting the secure exchange of data while upholding its level of safeguarding. [ABSTRACT FROM AUTHOR]

In today's world, optical fiber networks are susceptible to numerous cyber-attacks and conventional key distribution techniques that are limited by the growing computational power. By introducing Quantum Key Distribution (QKD) into optical networks, it is possible to leverage existing fiber infrastructures and apply wavelength division multiplexing (WDM) for effective secret key deployments to improve optical-layer security. Security is a major challenge during key exchange in QKD, at that same time restricted number of network resources also have a big concern recently. Thus a wavelength resources as well as security enhancement is performed through Time Continuous Compactness (TCC) based wavelength allocation algorithm with African Vulture Optimization (AVO) based BB84 protocol for quantum keys distribution. In this model, the dual secret key assembly is done through the KP (Key pool) and VKP (Virtualization Key Pool) assembly for storing the data in the SDN server, which can be accessed later using the user authentication. The data from the sender is encrypted using the AES-RC4 algorithm for transmitting to the receiver at the data channel. This designed model is evaluated and compared with the existing model based on the parameters such as key generation and eavesdropping rate. The attained key generation and eavesdropping rate (64 byte) of the proposed AVO-QKD model is 0.41 s and 0.45 Bps/Hz. These attained values of the proposed model are greater than the existing model. Thus, the Dual Secret Key virtualization through TCC based Wavelength Allocation and BB84 protocol in QKD over Optical Networks secures and allocates resources better than other techniques. [ABSTRACT FROM AUTHOR]

Because the spectrum of services available in modern telecommunication networks is constantly expanding, security has become increasingly important. Simultaneously, in an era of constant progress in mathematics and computing, the security of existing cryptographic solutions becomes questionable. Quantum Key Distribution (QKD) is a promising secret key agreement primitive that enables long-awaited practical Information-Theoretical Secure (ITS) communications. The key generation rate, however, is one of the limitations of its widespread application to secure high throughput data flows. This paper addresses the aforementioned limitation by employing perfectly correlated bases selection defined by the output of Pseudo-Random Functions based on the keyed-Hash Message Authentication Code construction. In theory, the proposed variant of the BB84 scheme is ITS, reduces memory requirements, and reduces communication overhead during the post-processing stage. It can benefit QKD networks as a service by increasing capacity and accommodating users with varying security needs.

The quantum key distribution (QKD) allows two remote users to share a common information-theoretic secure secret key. In order to guarantee the security of a practical QKD implementation, the physical system has to be fully characterized and all deviations from the ideal protocol due to various imperfections of realistic devices have to be taken into account in the security proof. In this work, we study the security of the efficient decoy-state BB84 QKD protocol in the presence of the source flaws, caused by imperfect intensity and polarization modulation. We investigate the non-Poissonian photon-number statistics due to coherent-state intensity fluctuations and the basis-dependence of the source due to non-ideal polarization state preparation. The analysis is supported by the experimental characterization of intensity and phase distributions. [ABSTRACT FROM AUTHOR]

Quantum key distribution (QKD) is considered the most immediate application to be widely implemented among a variety of potential quantum technologies. QKD enables sharing secret keys between distant users by using photons as information carriers. An ongoing endeavor is to implement these protocols in practice in a robust, and compact manner so as to be efficiently deployable in a range of real‐world scenarios. Single photon sources (SPS) in solid‐state materials are prime candidates in this respect. This article demonstrates a room temperature, discrete‐variable quantum key distribution system using a bright single photon source in hexagonal‐boron nitride, operating in free‐space. Employing an easily interchangeable photon source system, keys with one million bits length, and a secret key of approximately 70000 bits, at a quantum bit error rate of 6%, with ε‐security of 10−10 are generated. This study demonstrates the first proof of concept finite‐key BB84 QKD system realized with hBN defects. [ABSTRACT FROM AUTHOR]

This study introduces a novel approach to bolstering quantum key distribution (QKD) security by implementing swift classical channel authentication within the SARG04 and BB84 protocols. We propose mono-authentication, a pioneering paradigm employing quantum-resistant signature algorithms—specifically, CRYSTALS-DILITHIUM and RAINBOW—to authenticate solely at the conclusion of communication. Our numerical analysis comprehensively examines the performance of these algorithms across various block sizes (128, 192, and 256 bits) in both block-based and continuous photon transmission scenarios. Through 100 iterations of simulations, we meticulously assess the impact of noise levels on authentication efficacy. Our results notably highlight CRYSTALS-DILITHIUM’s consistent outperformance of RAINBOW, with signature overheads of approximately 0.5% for the QKD-BB84 protocol and 0.4% for the QKD-SARG04 one, when the quantum bit error rate (QBER) is augmented up to 8%. Moreover, our study unveils a correlation between higher security levels and increased authentication times, with CRYSTALS-DILITHIUM maintaining superior efficiency across all key rates up to 10,000 kb/s. These findings underscore the substantial cost and complexity reduction achieved by mono-authentication, particularly in noisy environments, paving the way for more resilient and efficient quantum communication systems.

We propose a simple and original implementation of the BB84 quantum key distribution protocol via a quantum frequency-translation process in a nonlinear optical fiber. Unlike most conventional quantum key distribution implementations, which rely on the photon polarization/phase, encoding quantum information in the photon frequency state is inherently more stable against mechanical and/or thermal fluctuations over transmission media such as optical fibers. We also show the proposed scheme to be naturally expandable to larger character sets, and demonstrate a straightforward extension to a four-character alphabet (qu-quarts), providing enhanced security for quantum key distribution applications. [ABSTRACT FROM AUTHOR]

Quantum Key Distribution (QKD) systems are thought to be the best method for securing data in cloud storage and boosting security and privacy. Due to the increasing use of cloud services, ensuring the confidentiality of stored data in cloud storage, data exchange, and key sharing used to encrypt data has become a major concern in recent years. The error key may occur during key generation. Through this error key, Eve can easily know the knowledge of the shared key. Enhanced error correction algorithms are utilized to discover and eliminate mistake bits while transmission, ensuring that both keys are equal and producing their shared error-free secret key. Hence, this study improves a BB84 protocol by improving its bit size at the compatibility level using the Sailfish Optimization Algorithm (SOA), and together with the transmitter, as well as the receiver, create a raw key in the next state. QKD is developed from improved BB84 protocol and encrypts data using a hybrid AES-RC4 encryption algorithm. The improved BB84 protocol generates the quantum key distribution, which encrypts data using a hybrid encryption algorithm. Here, error correction is done through the multi-objective function which is optimized using the Sailfish optimization technique, resulting in outcomes through adding either estimate mistake or a best key combination. After encryption, if the data is uploaded to the cloud, only the authorized user can decode the data. Moreover, in a Python environment, the proposed method is implemented, and the proposed model's accuracy rate is 97 per cent, with a 3 per cent error rate and 59 s for key generation time. As a result, the proposed SOA-based QKD swift key generation system outperforms existing methods. [ABSTRACT FROM AUTHOR]

Quantum cryptography was proposed as a counter to the capacity of quantum computers to break classical cryptosystems. A broad subclass of quantum cryptography, called quantum key distribution (QKD), relies on quantum mechanical process for secure distribution of the keys. Quantum channels are inherently noisy, and therefore these protocols will be susceptible to noise as well. In this paper, we study the performance of two QKD protocols — BB84 and E91 under amplitude damping error. We show that while E91 protocol loses its security immediately due to loss of entanglement, the performance of BB84 protocol reduces to random guessing with increasing time. Next, we consider the action of an Eve on the BB84 protocol under amplitude damping noise, who is restricted to guessing the outcome of the protocol only. Under this restriction, we show that Eve can still do better than random guessing when equipped with the characteristics of the noisy channel. Finally, we propose a modification of the BB84 protocol which retains the security of the original protocol, but ensures that Eve cannot get any advantage in guessing the outcome, even with complete channel information. [ABSTRACT FROM AUTHOR]

The quantum key distribution (QKD) allows two remote users to share a common information-theoretic secure secret key. In order to guarantee the security of a practical QKD implementation, the physical system has to be fully characterized and all deviations from the ideal protocol due to various imperfections of realistic devices have to be taken into account in the security proof. In this work, we study the security of the efficient decoy-state BB84 QKD protocol in the presence of the source flaws, caused by imperfect intensity and polarization modulation. We investigate the non-Poissonian photon-number statistics due to coherent-state intensity fluctuations and the basis-dependence of the source due to non-ideal polarization state preparation. The analysis is supported by the experimental characterization of intensity and phase distributions.

The formal modeling and verification of aircraft takeoff is a challenge because it is a complex safety-critical operation. The task of aircraft takeoff is distributed amongst various computer-based controllers, however, with the growing malicious threats a secure communication between aircraft and controllers becomes highly important. This research serves as a starting point for integration of BB84 quantum protocol with petri nets for secure modeling and verification of takeoff procedure. The integrated model combines the BB84 quantum cryptographic protocol with powerful verification tool support offered by petri nets. To model certain important properties of BB84, a new variant of petri nets coined as Quantum Nets are proposed by defining their mathematical foundations and overall system dynamics, furthermore, some important system properties are also abstractly defined. The proposed QuantumNets are then applied for modeling of aircraft takeoff process by defining three quantum nets: namely aircraft, runway controller and gate controller. For authentication between quantum nets, the use of external places and transitions is demonstrated to describe the encryptiondecryption process of qubits stream. Finally, the developed takeoff quantum network is verified through simulation offered by colored petri-net (CPN) Tools. Moreover, reachability tree (RT) analysis is also performed to have greater confidence in feasibility and correctness of the proposed aircraft takeoff model through the Quantum Nets. [ABSTRACT FROM AUTHOR]

Quantum key distribution (QKD) has been promoted as a means for secure communications. Although QKD has been widely implemented in many urban fiber networks, the large-scale deployment of QKD remains challenging. Today, researchers extensively conduct simulation-based evaluations for their designs and applications of large-scale QKD networks for cost efficiency. However, the existing discrete-event simulators offer models for QKD hardware and protocols based on sequential event execution, which limits the scale of the experiments. In this work, we explore parallel simulation of QKD networks to address this issue. Our contributions lay in the exploration of QKD network characteristics to be leveraged for parallel simulation as well as the development of a parallel simulation framework for QKD networks. We also investigate three techniques to improve the simulation performance including (1) a ladder queue based event list, (2) memoization for computationally intensive quantum state transformation information, and (3) optimization of the network partition scheme for workload balance. The experimental results show that our parallel simulator is 10 times faster than a sequential simulator when simulating a 128-node QKD network. Our linear-regression-based network partition scheme can further accelerate the simulation experiments up to two times over using a randomized network partition scheme. [ABSTRACT FROM AUTHOR]

Classical cryptographic system security relies on the complexity of mathematical problems and limited computational power available at the attacker's end. But with the advent of quantum computers that are assumed to have unlimited computational capability, classical cryptography is now proved to be no more unconditionally secure. It has been proved that the security of a cryptographic system depends on the key used for encryption, not the algorithm. Quantum Key Distribution (QKD) is a key sharing mechanism between two parties whose security relies on the very laws of nature (quantum mechanics), not on the computational capability of the eavesdropper. In QKD, if an eavesdropper tries to gain key information, then he will be detected immediately, and the key sharing procedure is aborted. In this paper, some of the most prominent QKD protocols proposed till now are studied and then a comparative analysis of those protocols depending on various factors is performed. [ABSTRACT FROM AUTHOR]

Quantum key distribution (QKD) protocols allow for information theoretically secure distribution of (classical) cryptographic key material. However, due to practical limitations the performance of QKD implementations is somewhat restricted. For this reason, it is crucial to find optimal protocol parameters, while guaranteeing information theoretic security. The performance of a QKD implementation is determined by the tightness of the underlying security analysis. In particular, the security analyses determines the key-rate, i.e., the amount of cryptographic key material that can be distributed per time unit. Nowadays, the security analyses of various QKD protocols are well understood. It is known that optimal protocol parameters, such as the number of decoy states and their intensities, can be found by solving a nonlinear optimization problem. The complexity of this optimization problem is typically handled by making a number of heuristic assumptions. For instance, the number of decoy states is restricted to only one or two, with one of the decoy intensities set to a fixed value, and vacuum states are ignored as they are assumed to contribute only marginally to the secure key-rate. These assumptions simplify the optimization problem and reduce the size of search space significantly. However, they also cause the security analysis to be non-tight, and thereby result in sub-optimal performance. In this work, we follow a more rigorous approach using both linear and nonlinear programs describing the optimization problem. Our approach, focusing on the decoy-state BB84 protocol, allows heuristic assumptions to be omitted, and therefore results in a tighter security analysis with better protocol parameters. We show an improved performance for the decoy-state BB84 QKD protocol, demonstrating that the heuristic assumptions typically made are too restrictive. Moreover, our improved optimization frameworks shows that the complexity of the performance optimization problem can also be handled without making heuristic assumptions, even with limited computational resources available. [ABSTRACT FROM AUTHOR]

Quantum key distribution (QKD) is a proven secured way to transmit shared secret keys using quantum particles. Any adversarial attempt to intercept and eavesdrop secret key results in generating errors alerting the legitimate users. Since QKD is constrained by quantum mechanics principles, the practical transmission of the key at a greater distance is an issue. In this paper, we discover and analyze the key factors associated with transmission media, hardware components and protocol implementation of the QKD system that causes hindrance in distance range. Practical implementation of BB84 and KMB09 protocols is discussed to determine the achievable distance given current technology. We find that by using ultra low loss fiber, short-pulse laser and superconducting nanowire single photon detector the maximum achievable distance for both of the quantum protocols is 250 km. [ABSTRACT FROM AUTHOR]

Quantum key distribution from satellites becomes particularly valuable when it can be used on a large network and on-demand to provide a symmetric encryption key to any two nodes. A constellation model is described which enables QKD-derived encryption keys to be established between any two ground stations with low latency. This is achieved through the use of low earth orbit trusted-node QKD satellites which create a buffer of keys with the ground stations they pass over, and geostationary relay satellites to transfer secure combinations of the keys to the ground stations. Regional and global network models are considered and the use of inter-satellite QKD links for balancing keys is assessed. • A Trusted-node satellite QKD network modelling architecture is described. • Different constellation topologies for delivering encryption keys are evaluated. • Inter-satellite QKD link are considered for rebalancing of keys. [ABSTRACT FROM AUTHOR]

A quantum key distribution protocol with single-particle and Bell state is proposed, in which one player Alice sends the states from some special single-particles and Bell states, the other player Bob measures these states in the single-particle basis or Bell basis, and then establish their secret key. Through combining the single-particle and Bell state novelly, the error rate of eavesdropping in our protocol can be increased up to 3 8 . Compared to BB84, our protocol can get higher secure key rate in practice. [ABSTRACT FROM AUTHOR]

This work illustrates a possible application of quantum game theory to the area of quantum information, in particular to quantum cryptography. The study proposed two quantum key‐distribution (QKD) protocols based on the quantum version of the Monty Hall game devised by Flitney and Abbott. Unlike most QKD protocols, in which the bits from which the key is going to be extracted are encoded in a basis choice (as in BB84), these are encoded in an operation choice. The first proposed protocol uses qutrits to describe the state of the system and the same game operators proposed by Flitney and Abbott. The motivation behind the second proposal is to simplify a possible physical implementation by adapting the formalism of the qutrit protocol to use qubits and simple logical quantum gates. In both protocols, the security relies on the violation of a Bell‐type inequality, for two qutrits and for six qubits in each case. Results show a higher ratio of violation than the E91 protocol. [ABSTRACT FROM AUTHOR]

Because the spectrum of services available in modern telecommunication networks is constantly expanding, security has become increasingly important. Simultaneously, in an era of constant progress in mathematics and computing, the security of existing cryptographic solutions becomes questionable. Quantum Key Distribution (QKD) is a promising secret key agreement primitive that enables long-awaited practical Information-Theoretical Secure (ITS) communications. The key generation rate, however, is one of the limitations of its widespread application to secure high throughput data flows. This paper addresses the aforementioned limitation by employing perfectly correlated bases selection defined by the output of Pseudo-Random Functions based on the keyed-Hash Message Authentication Code construction. In theory, the proposed variant of the BB84 scheme is ITS, reduces memory requirements, and reduces communication overhead during the post-processing stage. It can benefit QKD networks as a service by increasing capacity and accommodating users with varying security needs., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)