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  • Open Access

Incorporating Device Characterization into Security Proofs

Ernest Y.-Z. Tan and Shlok Nahar*

  • Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada

  • *Contact author: sanahar@uwaterloo.ca
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PRX Quantum 7, 020342 – Published 29 May, 2026

DOI: https://doi.org/10.1103/f42p-524t

Abstract

Typical security proofs for quantum key distribution (QKD) rely on having some model for the devices, with the security guarantees implicitly relying on the values of various parameters of the model, such as dark count rates or detector efficiencies. Hence to deploy QKD in practice, we must establish how to certify or characterize the model parameters of a manufacturer’s QKD devices. We present a rigorous framework for analyzing such procedures, laying out concrete requirements for both the security proofs and the certification or characterization procedures. In doing so, we describe various forms of conclusions that can and cannot be validly drawn from such procedures, addressing some potential misconceptions. We also discuss connections to composable security frameworks and some technical aspects that remain to be resolved in that direction.

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Popular Summary

Quantum cryptography is a potential near-term application of quantum technology. However, cryptographic security proofs rely on modeling the devices used in the protocol, in terms of assorted parameters that must lie within specified ranges for the security proofs to be valid. It is hence necessary to develop procedures for certifying the values of such parameters in these devices, before they are deployed in practice. In this work, we present a rigorous framework for analyzing such certification procedures, laying out requirements for both the practical and the theoretical aspects. We also clarify some boundaries regarding what statements are and are not achievable under such procedures. These results should establish the groundwork for further developments on the topic of certifying devices for implementations of quantum cryptography.

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References (39)

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PRX Quantum 7, 020342– Published 29 May, 2026
  • Received 25 November 2025
  • Revised 22 February 2026
  • Accepted 25 March 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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