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arXiv · 2601.18035

A rigorous and complete security proof of decoy-state BB84 quantum key distribution

Devashish Tupkary·Shlok Nahar·Amir Arqand·Ernest Y. -Z. Tan·Norbert Lütkenhaus
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Abstract

We present a rigorous and complete security proof of the decoy-state BB84 quantum key distribution (QKD) protocol. Our analysis aims to achieve a high standard of mathematical rigour and completeness, thereby providing the necessary foundation for certification and standardization efforts. Beyond establishing the security of a specific protocol, this work develops a general and modular framework that can be readily adapted to a broad class of QKD protocols, including both prepare-and-measure and entanglement-based variants. Our framework unifies all major ingredients required for the analysis of realistic QKD protocols, including the analysis of classical authentication and classical processing, source-replacement schemes, finite-size analysis, source maps, squashing maps, and decoy-state techniques. In doing so, this work consolidates a diverse range of techniques scattered across the QKD literature into a unified formalism, representing a general and rigorous treatment of QKD security. Finally, it outlines a clear path towards incorporating practical imperfections within the same framework, thereby laying the groundwork for addressing implementation security in future analysis.

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Devashish Tupkary, Shlok Nahar, Amir Arqand, Ernest Y. -Z. Tan, Norbert Lütkenhaus. 2026-01-25. A rigorous and complete security proof of decoy-state BB84 quantum key distribution. https://arxiv.org/abs/2601.18035

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