Performance Analysis of Different Quantum Key Distribution Protocols for Optimised Security and Efficiency

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.