Quantum key distribution: Bridging theoretical security proofs, practical attacks, and error correction for quantum-augmented networks

Quantum Key Distribution (QKD) is revolutionizing cryptography by promising information-theoretic security through the laws of quantum mechanics. Yet, the challenge of transforming these idealized security models into practical systems remains a pressing issue, especially as quantum computing evolves. In this review, we critically examine the latest advancements in QKD protocols and their security vulnerabilities, with an emphasis on rigorous security proofs. We actively categorize contemporary QKD schemes into three key classes: uncertainty principle-based protocols (e.g., BB84), hybrid architectures that enable secure direct communication (e.g., three-stage protocol), and continuous-variable frameworks. We further include two modern classes of QKD protocols, Twin-field and Device-Independent QKD, both of which were developed to have practical implementations over the last decade. Moreover, we highlight experimental breakthroughs and innovative mitigation strategies, including the deployment of advanced Quantum Error Correction Codes, that significantly enhance channel fidelity and system robustness. By mapping the current landscape, from sophisticated quantum attacks to state-of-the-art error-correction methods, this review fills an important gap in the literature. To bring everything together, the relevance of this review concerning quantum augmented networks (QuANets) is also presented. This allows the readers to gain a comprehensive understanding of the security promises of quantum key distribution from theoretical-proofs to experimental-validations.