Abstract : Quantum Key Distribution (QKD) is an innovative technology which exploits the laws of quantum mechanics to generate and distribute shared secret keying material. QKD systems generate and distribute key by progressing through a number of distinct phases, typically in a serial manner. The purpose of this research is to identify these phases, their relationships to each other, as well as their relationship to time, memory space, computational requirements, and hardware resources. A mathematical model is developed which enables the study of critical system parameters, identifies and demonstrates potential bottlenecks that affect the overall key generation rate of serial implementations, and facilitates the analysis of design trade-offs in terms of parameters associated with specific implementations. Existing models of throughput performance make use of secure key rate equations which do not account for detailed system parameters and performance characteristics, particularly in the post-processing phases. In this research we build a model that is abstract enough to be applied to a wide range of QKD system configurations. The results of the model form an accurate prediction of throughput. The analysis contained herein provides QKD practitioners guidance in system analysis and design.
Abstract : Quantum Key Distribution (QKD) is an innovative technology which exploits the laws of quantum mechanics to generate and distribute shared secret keying material. QKD systems generate and distribute key by progressing through a number of distinct phases, typically in a serial manner. The purpose of this research is to identify these phases, their relationships to each other, as well as their relationship to time, memory space, computational requirements, and hardware resources. A mathematical model is developed which enables the study of critical system parameters, identifies and demonstrates potential bottlenecks that affect the overall key generation rate of serial implementations, and facilitates the analysis of design trade-offs in terms of parameters associated with specific implementations. Existing models of throughput performance make use of secure key rate equations which do not account for detailed system parameters and performance characteristics, particularly in the post-processing phases. In this research we build a model that is abstract enough to be applied to a wide range of QKD system configurations. The results of the model form an accurate prediction of throughput. The analysis contained herein provides QKD practitioners guidance in system analysis and design.
Quantum key distribution (QKD) exploits the laws of quantum physics to generate shared secret cryptographic keys and can detect eavesdroppers during the key generation process. However, previous QKD research has focused more on theory than practice. QKD is the most mature application of the quantum information field, offering the means for two parties to generate secure cryptographic keying material. Employing the laws of quantum physics, QKD can detect eavesdroppers during the key generation process, in which unauthorized observation of quantum communication induces discernible errors. However, QKD is a nascent technology where real-world systems are constructed from nonideal components and deployed in uncertain operational environments, which can adversely impact system security and performance. In this article, we study the performance impact of QKD implementation nonidealities and practical engineering limitations, evaluating three system examples using a modularized simulation framework. We also explore the QKD security–performance trade space to gain additional understanding of critical design tradeoffs associated with interactions between physical components and system-level considerations such as hardware, software, and protocols. Such evaluations provide insight and inform designers, researchers, and users when selecting among competing solutions; decision makers can also use them to guide future investments and developmental efforts. Our research team focuses on bridging the gap between QKD theory and practice. Theoretical and experimental physicists are working to advance QKD technology, but few are strongly focused on evaluating and improving the implementation of realized systems. For a general introduction to QKD, see Chip Elliot’s “Quantum Cryptography.”
Quantum Key Distribution (QKD) systems exploit the laws of quantum mechanics to generate secure keying material for cryptographic purposes. To date, several commercially viable decoy state enabled QKD systems have been successfully demonstrated and show promise for high-security applications such as banking, government, and military environments. In this work, a detailed performance analysis of decoy state enabled QKD systems is conducted through model and simulation of several common decoy state configurations. The results of this study uniquely demonstrate that the decoy state protocol can ensure Photon Number Splitting (PNS) attacks are detected with high confidence, while maximizing the system’s quantum throughput at no additional cost. Additionally, implementation security guidance is provided for QKD system developers and users.
Quantum Key Distribution (QKD) is an innovative technology which exploits the laws of quantum physics to generate and distribute shared secret key for use in cryptographic devices. Quantum Key Distribution offers the advantage of ‘unconditionally secure’ key generation with the unique ability to detect eavesdropping on the key distribution channel and shows promise for high-security applications such as those found in banking, government, and military environments. However, Quantum Key Distribution is a nascent technology where realized systems suffer from implementation non-idealities, which may significantly impact system performance and security. In this article, we discuss the modeling of a decoy state enabled Quantum Key Distribution system built to study the impact of these practical limitations. Specifically, we present a thorough background on the decoy state protocol, detailed discussion of the modeled decoy state enabled Quantum Key Distribution system, and evidence for component and sub-system verification, as well as, multiple examples of system-level validation. Additionally, we bring attention to practical considerations associated with implementing the decoy state protocol security condition gained from these research activities.
Quantum Key Distribution (QKD) systems are a novel technology that exploits the laws of quantum mechanics to generate and distribute unconditionally secure cryptographic keys between two geographically separated parties. They are suitable for use in applications where high levels of secrecy are required, such as banking, government, and military environments. In this paper, we describe the development of a module-based QKD simulation framework that facilitates the modeling of QKD post-processing functionalities. We highlight design choices made to improve upon an initial design, which included the segmentation of functionalities associated with various phases of QKD post-processing into discrete modules implementing abstract interfaces. In addition, communication between modules was improved by implementing observers to share data, and a specific strategy for dealing with post-processing synchronization and configuration activities was designed. Collectively, these improvements resulted in a significantly enhanced analysis capability to model and study the security and performance characteristics associated with specific QKD system designs.
The use of quantum key distribution (QKD) to improve security may impact the quality of service (Qos) of high rate classical data links. The key generation process with an empty buffer can be modeled as a queuing system, and data throughput limits can be determined using queueing theory to assess the impact on the QoS. The proposed key generation model is based on an on-demand paradigm. Based on the results of this study, a discrete variable (DV)-QKD-secured link could be designed using the data rate bounds to guarantee a given QoS. Furthermore, we validate the derived bounds by comparing the theoretical derivations with simulations. We show that in a one-time-pad system, the achievable throughput approaches 0.59 times the secret key rate as the key length increases. In the case of a key scheme with key reuse, the throughput is asymptotically linear with the number of key reuses, and the slope of the curve corresponds to the secret key rate multiplied by a function of the protocol and channel characteristics. The analysis is carried out on optical fiber and free-space links.
Quantum computing advances pose a serious threat to conventional public-key cryptographic systems such as RSA and elliptic curve cryptography as quantum algorithms may undermine the computational assumptions that guaranty their security. This challenge has driven the development of quantumsafe security approaches among which Quantum Key Distribution (QKD) represents a fundamentally different paradigm based on quantum mechanical principles rather than mathematical complexity. This paper presents a structured review of recent progress in QKD based on a systematic analysis of literature between 2020 and 2025, we examine core protocols including discrete-variable, continuous-variable, measurement-deviceindependent, and twin-field approaches, while also discussing their relationship with post-quantum cryptography as a complementary strategy for future secure communication systems. We provide a unified comparison framework to support practical design and policy decisions by organizing protocols and implementations along deployment dimensions. The study analyze theoretical foundations, implementation technologies across fiber, free-space, satellite, and integrated photonic platforms, and key performance trade-offs involving scalability, security robustness, and deployment feasibility. Findings indicate substantial progress in transitioning QKD from laboratory research toward practical implementations, supported by advances in network architectures, integrated hardware and hybrid cryptographic designs. The comparative analysis will highlight distinct strengths and limitations among protocol families and emphasize the potential of combining QKD with post-quantum cryptographic methods to enhance resilience. Remaining challenges including scalability constraints, implementation-level vulnerabilities, performance limitations over long distances, and integration with existing communication infrastructures are critically discussed. Finally, emerging research directions such as quantum repeaters, hybrid quantum-classical security models, and exploratory directions such as artificial intelligence-assisted optimizations are identified as key factors in enabling the evolution of QKD toward largescale quantum-secure networking.