Quantum key distribution (QKD) protocols fall into two main categories: entanglement‐based and non‐entanglement‐based. Although entanglement‐based QKD offers strong security, it theoretically generates fewer keys with the same number of logical qubits. In contrast, the non‐entanglement‐based method produces more keys but with reduced security. To address these concerns, in this article, we present a novel hybrid QKD protocol that combines both approaches to optimize security and key generation. We introduce a dynamic system that integrates a three‐particle entangled Greenberger–Horne–Zeilinger (GHZ)‐state method with the two‐particle BB84 QKD protocol, using a quantum superposition state to probabilistically switch between them. The GHZ state component leverages strong three‐particle entanglement correlations for enhanced security, while the BB84 component offers simplicity and potentially a higher number of key generation. This protocol was implemented and simulated using IBM’s Qiskit and IBM Quantum Platform; our approach demonstrates 63.48% higher number of key generation compared to the E91 protocol, although 37. 33% lower than the standalone BB84 protocol while maintaining robust security and being less prone to quantum bit error rate (QBER). The results and security discussion show that this combined method effectively balances the trade‐offs inherent in QKD systems, offering a flexible framework adaptable to varying channel conditions and security requirements.
Quantum key distribution (QKD) protocols fall into two main categories: entanglement‐based and non‐entanglement‐based. Although entanglement‐based QKD offers strong security, it theoretically generates fewer keys with the same number of logical qubits. In contrast, the non‐entanglement‐based method produces more keys but with reduced security. To address these concerns, in this article, we present a novel hybrid QKD protocol that combines both approaches to optimize security and key generation. We introduce a dynamic system that integrates a three‐particle entangled Greenberger–Horne–Zeilinger (GHZ)‐state method with the two‐particle BB84 QKD protocol, using a quantum superposition state to probabilistically switch between them. The GHZ state component leverages strong three‐particle entanglement correlations for enhanced security, while the BB84 component offers simplicity and potentially a higher number of key generation. This protocol was implemented and simulated using IBM’s Qiskit and IBM Quantum Platform; our approach demonstrates 63.48% higher number of key generation compared to the E91 protocol, although 37. 33% lower than the standalone BB84 protocol while maintaining robust security and being less prone to quantum bit error rate (QBER). The results and security discussion show that this combined method effectively balances the trade‐offs inherent in QKD systems, offering a flexible framework adaptable to varying channel conditions and security requirements.
This paper presents a novel hybrid Quantum Key Distribution ,QKD, protocol that combines entanglement based and non entanglement based approaches to optimize security and the number of generated keys. We introduce a dynamic system that integrates a three particle GHZ state method with the two state B92 protocol, using a quantum superposition state to probabilistically switch between them. The GHZ state component leverages strong three particle entanglement correlations for enhanced security, while the B92 component offers simplicity and potentially higher key generation rates. Implemented and simulated using Qiskit, our approach demonstrates higher number of generated keys compared to standalone protocols while maintaining robust security. We present a comprehensive analysis of the security properties and performance characteristics of the proposed protocol. The results show that this combined method effectively balances the trade offs inherent in QKD systems, offering a flexible framework adaptable to varying channel conditions and security requirements.This research contributes to ongoing efforts to make QKD more practical and efficient, potentially advancing the development of large scale, secured quantum networks.
ABSTRACT The rapid evolution of quantum computing poses a significant threat to classical cryptographic systems like Rivest‐Shamir‐Adleman (RSA) and Elliptic Curve Cryptography (ECC), which rely on the computational hardness of problems such as integer factorization and discrete logarithms. Quantum algorithms such as Shor's algorithm can solve these problems quickly, which undermines the foundations on which classical cryptography relies. Quantum Key Distribution (QKD) is an alternative to the classical methods, which promises information‐theoretic security based on quantum mechanics. Currently, there are existing QKD protocols, including BB84, B92, E91, and GHZ, all of which exhibit various real‐world limitations. For example, these QKD protocols can be vulnerable to a variety of side‐channel attacks (e.g., detector blinding, photon‐number‐splitting) and neglect to consider fluctuating network conditions. Current QKD protocols also fail to accommodate scalability for many‐to‐many or noise‐limited scenarios. Many implementations of the existing QKD protocols and other common forms of networks remain static, relying on arbitrary decisions of fixed values that yield simple linear conclusions that can be predicted and targeted in the real‐world environment. To address these omissions, we propose a new framework for dynamic or adaptive hybrid QKD in which we incorporate BB84, B92, E91, and GHZ into one common approach with all protocols selected based on a probability‐weighted distribution of (0.3, 0.2, 0.3, 0.2). In the hybrid QKD implementation, the probability weights of protocol selection are assigned with partiality toward BB84, E91, B92, and GHZ, respectively. This may also introduce a higher variety of protocols and diversity in approaches that will further limit cross‐protocol possibilities of attack vectors, while increasing the possible flexibility of adaptability in attacked situations. In addition, we incorporate an artificial intelligence (AI)‐based optimization module using a neural network to evaluate local environmental noise and quantum bit error rate (QBER) in real time. It adjusts protocol selection probabilities dynamically based on both historical and live operational data to optimize throughput while maintaining low error rates. The system architecture supports modular and parallel operation and has been mapped out and designed to be scalable and compatible with future quantum networks. We test our system using IBM's Qiskit AerSimulator utilizing a 14‐qubit register with 100 rounds of a 1% depolarization noise model, which significantly outperformed static hybrids such as Chen et al. in terms of both key rate and QBER. Our system consistently produced an average QBER of 0.02 and a key generation rate of 12 bits per round. E91 consistently produced CHSH violating confirming the fidelity of the entanglement, while BB84 displayed no QBER on all rounds. This work demonstrates the first fully integrated, AI‐assisted, dynamic hybrid QKD system. It includes all advantageous features of a QKD protocol: the dynamic adaptability of the protocol allows for a performance driven environment, the use of entangled states provides increased security, and a bottom‐up approach to real‐time optimization creating a robust, scalable, and agnostic system to any hardware used by post‐quantum cryptographic infrastructures.
Quantum Key Distribution (QKD) protocols involve a practical trade-off between key-generation throughput, hardware resources, and verification capability. Prepare-and-measure schemes such as BB84 are efficient for key generation, whereas entanglement-based schemes using Greenberger–Horne–Zeilinger (GHZ) states provide multipartite correlation checks but require more qubits and are more sensitive to current hardware noise. This work presents an implementation-oriented enhancement of a previously proposed GHZ–BB84 hybrid QKD architecture. Instead of using a fixed 50/50 protocol-selection schedule, we introduce an incrementally biased Ry-based selection circuit that increases the probability of selecting BB84 rounds after successful selection measurements while retaining a nonzero fraction of GHZ rounds for periodic correlation verification and key generation. We derive the selection probabilities for the accepted rounds and evaluate the resulting biased hybrid implementation using Qiskit and an IBM Quantum Device. In the 1000-state experiment, the enhanced combined protocol generated 477 final key bits, achieving ∼96.75% of the pure BB84 key count of 493 bits while retaining 10 GHZ-selected rounds out of 125 accepted rounds. Compared with the previous 50/50 hybrid baseline, the proposed selection schedule improves the final key-generation rate by 43.67%, increases qubit-use efficiency to 31.38%, and reduces the observed Quantum Bit Error Rate from ∼4% to about 1%. These results show that the biased selection schedule provides a practical rate–resource operating point for hybrid QKD implementations. The GHZ rounds are used for intermittent verification and key generation and are not assumed to transfer entanglement-based security guarantees to BB84 rounds; BB84-selected rounds retain the standard BB84 security requirements.
Secure communication has become essential due to the rapid increase in cyber-attacks and data security threats in modern networks. Traditional communication systems mainly rely on classical security methods, which may become vulnerable to advanced attacks. Quantum Key Distribution (QKD) improves secure communication by generating cryptographic keys using quantum principles, making key interception extremely difficult. In this work, a Quantum Random Number Generator (QRNG) is integrated with classical communication to develop a hybrid quantum-classical communication framework. The QRNG generates highly random bits that improve authentication, randomness, and key security. The proposed system compares three QKD protocols: BB84, B92, and E91 using different bit sizes of 8000, 10000, and 13000 bits. The protocols are evaluated using important metrics such as QBER, key rate, entropy, erasure rate, throughput, and correlation. Experimental results show that all protocols achieved entropy values close to 1 and correlation values near zero, indicating strong randomness and secure key generation. Among the evaluated protocols, E91 achieved lower QBER values and higher key rates, while BB84 showed stable and reliable performance. B92 produced comparatively higher error rates under similar conditions. The throughput remained nearly 278–281 bits/sec across all experiments. A ranking-based analysis confirmed that E91 provides the best balance between security, efficiency, and communication performance, making it suitable for future quantum-secure communication systems.
Conventional Quantum Key Distribution (QKD) requires the transmission of qubits proportional to or exceeding the length of the key, as protocols such as BB84 transmit more qubits than the final key size due to basis sifting and privacy amplification. Since quantum networks are still in their infancy and have limited capacity, this overhead puts significant pressure on network resources. To address this issue, we propose a Multi-Qubit Greenberger--Horne--Zeilinger (GHZ) State-based QKD scheme that reduces the number of qubits transmitted over the quantum channel. The proposed method transmits one GHZ qubit between endpoints and reuses the resulting entanglement to convey multiple classical key bits with the help of Quantum Non-Demolition (QND) measurements. Under the stated assumptions on authenticated classical communication, local reset verification, and bounded-error QND discrimination, one can transfer L classical bits by generating an (L+1)-qubit GHZ state and transferring one qubit to the remote party. We verify correctness using the NetSquid quantum network simulator: the protocol achieves 100\% raw-key fidelity for keys of length up to 12 bits under both ideal conditions and depolarizing noise up to p = 0.005 per round. We further show that the proposed QKD algorithm can be extended to multi-party QKD and server-client deployment. The proposed scheme offers a transmitted-qubit-efficient, noise-tolerant alternative for bandwidth-limited quantum networks.
Quantum Key Distribution (QKD) represents a revolutionary advancement in secure communication. It leverages principles of quantum mechanics to establish cryptographic keys between parties with theoretically unbreakable security. Among the various QKD protocols, BB84 (Bennett and Brassard, 1984) and Twin-Field QKD are prominent due to their foundational simplicity and advanced key generation efficiency, respectively. The BB84 protocol, as the first QKD protocol, uses quantum bits (qubits) in different bases to securely generate shared keys, while Twin-Field QKD enhances the key generation rate by exploiting quantum interference between distant entangled states, making it more suitable for long-distance communication. This work explores the integration of BB84 and Twin-Field QKD into a hybrid algorithm, aiming at combining the robustness of BB84 with the high key generation rate and entropy of Twin-Field QKD. The hybrid algorithm alternates between the two protocols, leveraging their individual strengths to optimize key generation performance. Simulation results indicate that the hybrid algorithm can effectively balance the robustness and simplicity of BB84 with the high efficiency and entropy of Twin-Field QKD. Specifically, the hybrid algorithm demonstrated an error rate of 8.9%, a key generation rate of 50%, and an entropy of 0.999 bits, which outperforms the compared algorithms.