Integrated BB84 Quantum Key Distribution for Hybrid Cryptographic Systems

The rapid progress of quantum computing threatens the long-term reliability of conventionalcryptographic algorithms, driving the urgent need for defenses that remain secure in a postquantum environment. This study introduces a unified hybrid encryption framework thatcombines the BB84-based Quantum Key Distribution (QKD) scheme with classical AES-256encryption, supported by continuous real-time security analytics. Although QKD has beenexamined extensively from a theoretical standpoint, its integration with traditional encryptionmethods for real-world communication is still uncommon. In this work, the complete BB84protocol is implemented using Google’s Cirq platform and augmented with adaptivemonitoring, quantum error diagnostics, and multi-layered security evaluation metrics.Simulation experiments verify the system’s strong performance, achieving an averageQuantum Bit Error Rate (QBER) of 4.5%, key reconciliation efficiency of 89.2%, and reliableencrypted data exchange. The platform further enables immediate detection of eavesdroppingattempts and detailed visualization of security states, thereby closing existing gaps in hybridquantum-classical encryption research and advancing the development of practical quantumsafe communication infrastructures.