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.
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.
Quantum Key Distribution (QKD) is increasingly recognized as a robust solution to the vulnerabilities posed by quantum computing to classical encryption systems. This paper presents a comprehensive investigation of the BB84 protocol, the foundational QKD scheme, through simulated quantum communication using IBM’s Qiskit framework. The study models quantum key exchange under both ideal and adversarial conditions, including channel noise and intercept-resend attacks. The Quantum Bit Error Rate (QBER) was measured as a function of noise intensity and eavesdropping, confirming that QBER increases predictably in compromised channels. A threshold of 11% QBER was used to determine the viability of secure key generation. Final key retention rates were analyzed across multiple channel scenarios, revealing BB84’s sensitivity to both photon loss and adversarial interference.\n\nSecurity vulnerabilities such as photon-number-splitting and detector blinding were assessed, and countermeasures including decoy-state protocols and authenticated classical channels were proposed. Four key performance graphs were generated to visualize system behavior under realistic operational conditions. The results support BB84’s theoretical advantage in ensuring information-theoretic security while acknowledging real-world limitations in transmission range and hardware reliability. The paper concludes by addressing future improvements in QKD systems, including satellite-based distribution, quantum repeaters, and device-independent implementations. Through simulation-driven analysis, this study validates BB84 as a practical defense against quantum-enabled attacks and underscores the need for continued development and standardization in post-quantum cryptographic infrastructure.
Quantum cryptography offers possibilities to distribute keys securely by relying on the principles of quantum mechanics. This paper presents repeatable simulations of two well-known quantum key distribution protocols, BB84 and E91, and examines how eavesdropping, noise, and transmission losses affect their security. The simulations are carried out using the Qiskit framework. A theoretical analysis of the expected quantum bit error rate (QBER) under ideal conditions and during an intercept–resend attack is included. The Clauser–Horne–Shimony–Holt (CHSH) parameter is also evaluated for the entanglement-based protocol. The results show error rates close to zero without attack, an increase to about 25\% under eavesdropping, and reduced correlations in the presence of attacks or losses. For the E91 protocol, the CHSH parameter exceeds the classical bound (S >2) in the entangled scenario and drops below the classical limit (S <= 2) in the attack case.
Quantum Key Distribution (QKD) has emerged as a critical component of secure communication in the post-quantum era. This study provides a comparative security and performance analysis of leading QKD protocols—BB84, E91, and Continuous Variable QKD—using experimental and simulated data from terrestrial and satellite-based implementations. Key metrics such as secret key rate, bit error rate, and resistance to quantum attacks are analyzed. Regression and predictive modeling are used to quantify performance decay over distance and noise. The results indicate BB84's robustness and broad applicability, while CV-QKD offers throughput advantages in short-range networks. Keywords: Quantum Key Distribution, QKD, BB84, E91, Continuous Variable QKD, Cryptographic Security, Quantum Communication, Post-Quantum Security
Abstract This paper investigates practical performances of the Ekert 91 protocol (E91) for future secure quantum networks. To seek future possible improvement, we investigate the important different principles of E91 and Bennet-Brasard (BB84) protocols. We perform a series of computer simulations to evaluate the performances of them and investigate the practical parameters. Furthermore, we simulate the E91 protocol using real-world practical scenarios involving eavesdropping and quantum channel errors. We present two scenarios: (1) the performance with eavesdropper interception under a perfect channel and (2) the performances with eavesdropper interception combined with channel errors. We found that: (i) the E91 protocol produces fewer keys compared to the BB84 protocol but does not require verification between two parties, (ii) the E91 protocol enhances security due to the utilization of Clauser, Horne, Shimony, and Holt (CHSH) inequality, and (iii) both eavesdropper and channel errors can impact the less production of keys obtained during the keys production.
Abstract Quantum Key Distribution (QKD) is a cornerstone of next-generation cryptographic technologies, offering unparalleled security by utilizing the principles of quantum mechanics. However, practical implementations of QKD face significant challenges, including inefficiencies in key generation, susceptibility to noise, and vulnerabilities to eavesdropping. This work addresses these challenges by proposing a machine learning (ML)-driven approach to optimize QKD protocols, focusing on enhancing both efficiency and security. In this work it is intended to evaluate three advanced protocols Adaptive, Entanglement-Based, and Hybrid under varying conditions such as key length, noise levels, and channel stability. The ML models will include ensemble learning models namely Random Forest and XGBoost, the models will analyze the impact of key parameters on protocol performance and predict efficiency with high accuracy. The results reveal that the Adaptive protocol significantly outperforms the Entanglement-Based and Hybrid protocols, achieving an efficiency of up to 0.80 for a key length of 2500 bits, compared to 0.24 for the Entanglement-Based protocol and 0.26 for the Hybrid protocol. The Adaptive protocol also demonstrates superior detection probability (ranging from 0.84 to 0.85) and a higher probability of detecting eavesdropping (ranging from 0.43 to 0.45). Furthermore, correlation analysis shows a strong positive relationship (r = 0.9985) between key length and efficiency for the Adaptive protocol, highlighting its scalability. In contrast, the Entanglement-Based protocol shows consistent but lower performance across all metrics, while the Hybrid protocol offers a compromise but remains less efficient than the Adaptive protocol. By integrating ML with quantum cryptography, this work bridges the gap between theoretical advancements and practical implementations, providing a scalable framework for optimizing QKD systems in real-world applications. The findings underscore the importance of protocol design and optimization in achieving secure and efficient quantum communication, paving the way for the quantum internet of the future.
Quantum computing poses significant threats to conventional cryptographic techniques such as RSA and AES, motivating the need for quantum secure communication methods. Quantum Key Distribution (QKD) offers information theoretic security based on fundamental quantum principles. This paper presents a simulation-based analysis of well-known QKD protocols, namely BB84, B92, and E91, using the IBM Qiskit framework. Realistic quantum channel effects, including noise, decoherence, and eavesdropping, are modeled to evaluate protocol performance. Key metrics such as error rate, secret key generation, and security characteristics are analyzed and compared. The study highlights practical challenges in QKD implementation, including hardware limitations and channel losses, and discusses insights toward scalable and robust quantum communication systems. The results support the feasibility of QKD as a promising solution for secure communication in the quantum era.