Quantum Key Distribution (QKD) enables two parties to securely share encryption keys by leveraging the principles of quantum mechanics, offering protection against eavesdropping. In practical implementations, QKD systems often rely on a layered architecture where a key manager stores secret key material in a buffer and delivers it to higher communication layers as needed. However, this buffer can be depleted under high demand, requiring efficient replenishment strategies that minimize resource waste. Given the importance of optimizing time and resources in quantum cryptography protocols, we introduce a variable-length adaptation of the BB84 protocol designed to meet user-defined output key length constraints in non-ideal scenarios. We present a method for dynamically configuring the protocol’s initial parameters to generate secret keys of a desired length. To validate our approach, we developed simulation tools to model general QKD networks and discrete-variable protocols. These tools were used to implement and evaluate our strategies, which were developed within the BB84 framework but can be extended to other QKD protocols under reasonable assumptions. The results highlight their usefulness in optimizing quantum resource usage and supporting key management, contributing to the long-term goal of scaling and strengthening secure quantum networks.
Quantum Key Distribution (QKD) enables two parties to securely share encryption keys by leveraging the principles of quantum mechanics, offering protection against eavesdropping. In practical implementations, QKD systems often rely on a layered architecture where a key manager stores secret key material in a buffer and delivers it to higher communication layers as needed. However, this buffer can be depleted under high demand, requiring efficient replenishment strategies that minimize resource waste. Given the importance of optimizing time and resources in quantum cryptography protocols, we introduce a variable-length adaptation of the BB84 protocol designed to meet user-defined output key length constraints in non-ideal scenarios. We present a method for dynamically configuring the protocol’s initial parameters to generate secret keys of a desired length. To validate our approach, we developed simulation tools to model general QKD networks and discrete-variable protocols. These tools were used to implement and evaluate our strategies, which were developed within the BB84 framework but can be extended to other QKD protocols under reasonable assumptions. The results highlight their usefulness in optimizing quantum resource usage and supporting key management, contributing to the long-term goal of scaling and strengthening secure quantum networks.
Quantum technologies promise to boost ICT further by extending its limits, even by promising more effective and secure communications due to the benefits of quantum physics. This leads to Quantum Key Distribution (QKD), a cryptographic primitive for securely exchanging a secret key between distant endpoints, leveraging an insecure communication channel due to potential eavesdroppers. The literature on QKD started with the BB84 protocol proposed in 1984 and continued with other protocols, each with its pros and cons. Still, they have been chiefly designed for static scenarios and do not consider the needs of dynamic networks. This paper presents a QKD solution for dynamic networks combining adaptive key management techniques and fault-tolerant routing, ensuring high security and efficiency even in variable network topologies. Using MDI-QKD (Measurement Device Independent QKD) and simulations with NetSquid, we provide a preliminary assessment of this solution's robustness against dynamic attacks and the improvement in quantum resource management. The work also compares the protocol's effectiveness with existing solutions, highlighting the advantages and potential practical applications.
Quantum Key Distribution (QKD) is a foundational method for the secure generation and distribution of cryptographic keys between network nodes, relying on quantum mechanical principles to provide information-theoretic security. As quantum computing continues to advance, the development of quantum communication networks requires the implementation of complex and secure architectures. However, the deployment of such networks demands considerable financial, technical, and human resources. In this context, simulation tools are essential, as they enable researchers to validate theoretical models, optimize network design, and identify potential vulnerabilities without the need for costly physical infrastructure. The goal of the research was to evaluate the efficiency and accuracy of QNET simulation tool by comparing the outcomes of developed simulation models with empirical data from real QKD networks. While the results in some cases closely aligned indicating a high level of accuracy in modeling QKD networks noticeable discrepancies were observed in certain scenarios. Such an approach not only facilitates more accurate modeling and planning but also promotes the development of scalable, cost effective, and secure quantum communication systems.
Quantum key distribution (QKD) allows the distribution of secret keys for quantum-secure communication between two distant parties, vital in the quantum computing era in order to protect against quantum-enabled attackers. However, overcoming rate-distance limits in QKD and the establishment of quantum key distribution networks necessitate key relaying over trusted nodes. This process may be resource-intensive, consuming a substantial share of the scarce QKD key material to establish end-to-end secret keys. Hence, an efficient scheme for key relaying and the establishment of end-to-end key pools is essential for practical and extended quantum-secured networking. In this paper, we propose and compare two protocols for managing, storing, and distributing secret key material in QKD networks, addressing challenges such as the success rate of key requests, key consumption, and overhead resulting from relaying. We present an innovative, fully decentralized key distribution strategy as an alternative to the traditional hop-by-hop relaying via trusted nodes, where three experiments are considered to evaluate performance metrics under varying key demand. Our results show that the decentralized pre-flooding approach achieves higher success rates as application demands increase. This analysis highlights the strengths of each approach in enhancing QKD network performance, offering valuable insights for developing robust key distribution strategies in different scenarios.
Quantum key distribution (QKD) can provide secure key material between two parties without relying on assumptions about the computational power of an eavesdropper. QKD is performed over quantum links and quantum networks, systems which are resource-intensive to deploy and maintain. To evaluate and optimize performance prior to, during, and after deployment, accurate simulations with attention to physical realism are necessary. Quantum network simulators can simulate a variety of quantum and classical protocols and can assist in quantum network design and optimization by offering realism and flexibility beyond mathematical models which rely on simplifying assumptions and can be intractable to solve as network complexity increases. We use a versatile discrete event quantum network simulator to simulate the entanglement-based QKD protocol BBM92 and compare it to our experimental implementation and to existing theory. We find the discrete event quantum network simulator can match experimental key rates and error rates with a lower mean squared error than analytical theory. Furthermore, we simulate secure key rates in a repeater key distribution scenario for which no experimental implementations exist and find agreement between simulation and analytical theory. Hence, we demonstrate discrete event simulators can meet needs in quantum network simulations which cannot be filled solely by experiment or theory: discrete event simulators can accurately simulate QKD protocols and match experiments in regimes where theoretical models may require more simplifying assumptions, and they can match theoretical models in the opposite scenario where experiments have not yet been performed but theoretical models exist.
Quantum key distribution (QKD) enables secure communication using the principles of quantum physics. The BB84 protocol is not only effective for secure key sharing but also for detecting eavesdropping. This study simulates a computational model of QKD and analyzes error rates under varying numbers of bits. Using Python-based simulations with n = 10, n = 100, and n = 1000 bits, and a fixed noise probability of 0.02, we evaluated scenarios both with and without eavesdropping over 1000 trials. The results show an average error rate of 2% without eavesdropping and over 26% with eavesdropping. Standard deviation increases with lower n, indicating higher variability. This study validates BB84’s robustness under noise and demonstrates its sensitivity to third-party interference.
ABSTRACT Quantum key distribution (QKD) protocols are techniques that use the laws of quantum physics to safely distribute cryptographic keys. QKD protocols are able to identify attempts at eavesdropping during the distribution of keys, possibly providing a better level of security than traditional encryption. We present a comparative evaluation of the three QKD protocols, namely, BB84, E91 and an enhanced BB84 (EBB84) with the goal of identifying the best balance between security and efficiency for practical quantum communication systems. Motivated by the growing need for quantum‐resistant cryptography, extensive simulations in the Qiskit framework under both ideal and plausible noisy conditions is conducted, including depolarising, thermal relaxation, Pauli, amplitude damping and phase damping noise models. For each protocol, key lengths are varied from 200 to 3000 bits and, where relevant, simulated intercept–resend attacks to assess resilience against eavesdropping. The key performance metrics, QBER for BB84/EBB84 and the CHSH inequality parameter for E91 are computed over 50 iterations per scenario to ensure statistical robustness. The analysis reveals distinct trade‐offs: EBB84 achieves superior early eavesdropper detection at short key lengths, whereas differences between BB84 and EBB84 diminishes as key lengths increases; E91 maintains strong entanglement‐based security but is more sensitive to certain noise types. Regression analysis confirms that depolarising and amplitude damping noise most strongly influence QBER and CHSH degradation, whereas key length has a secondary effect. These findings mark the importance of adaptive key management and noise mitigation strategies and offer guidelines for integrating QKD into emerging network architectures such as SDN, 5G, and 6G.