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A Critical Analysis of Deployed Use Cases for Quantum Key Distribution and Comparison with Post-Quantum Cryptography

Nick Aquina, Bruno Cimoli, Soumya Das, Kathrin Hövelmanns, Fiona Johanna Weber, Chigo Okonkwo, Simon Rommel, Boris Škorić, Idelfonso Tafur Monroy, Sebastian Verschoor

TL;DR

This work surveys deployed QKD use cases and compares them to Post-Quantum Cryptography (PQC) to assess where quantum-secure solutions add real value. It systematically analyzes real-world deployments, focusing on how keys are used, network topology, and the concrete security guarantees achieved, then contrasts these with PQC-based alternatives. The findings indicate that, in most cases, QKD offers limited advantages over PQC or pre-shared keys, with notable exceptions where QKD is paired with one-time pads for short-distance transport. The study emphasizes that decision-makers should weigh implementation complexity, scalability, and long-term security when choosing between QKD and PQC, identifying niche scenarios where QKD with OTP could provide everlasting confidentiality.

Abstract

Quantum Key Distribution (QKD) is currently being discussed as a technology to safeguard communication in a future where quantum computers compromise traditional public-key cryptosystems. In this paper, we conduct a comprehensive security evaluation of QKD-based solutions, focusing on real-world use cases sourced from academic literature and industry reports. We analyze these use cases, assess their security and identify the possible advantages of deploying QKD-based solutions. We further compare QKD-based solutions with Post-Quantum Cryptography (PQC), the alternative approach to achieving security when quantum computers compromise traditional public-key cryptosystems, evaluating their respective suitability for each scenario. Based on this comparative analysis, we critically discuss and comment on which use cases QKD is suited for, considering factors such as implementation complexity, scalability, and long-term security. Our findings contribute to a better understanding of the role QKD could play in future cryptographic infrastructures and offer guidance to decision-makers considering the deployment of QKD.

A Critical Analysis of Deployed Use Cases for Quantum Key Distribution and Comparison with Post-Quantum Cryptography

TL;DR

This work surveys deployed QKD use cases and compares them to Post-Quantum Cryptography (PQC) to assess where quantum-secure solutions add real value. It systematically analyzes real-world deployments, focusing on how keys are used, network topology, and the concrete security guarantees achieved, then contrasts these with PQC-based alternatives. The findings indicate that, in most cases, QKD offers limited advantages over PQC or pre-shared keys, with notable exceptions where QKD is paired with one-time pads for short-distance transport. The study emphasizes that decision-makers should weigh implementation complexity, scalability, and long-term security when choosing between QKD and PQC, identifying niche scenarios where QKD with OTP could provide everlasting confidentiality.

Abstract

Quantum Key Distribution (QKD) is currently being discussed as a technology to safeguard communication in a future where quantum computers compromise traditional public-key cryptosystems. In this paper, we conduct a comprehensive security evaluation of QKD-based solutions, focusing on real-world use cases sourced from academic literature and industry reports. We analyze these use cases, assess their security and identify the possible advantages of deploying QKD-based solutions. We further compare QKD-based solutions with Post-Quantum Cryptography (PQC), the alternative approach to achieving security when quantum computers compromise traditional public-key cryptosystems, evaluating their respective suitability for each scenario. Based on this comparative analysis, we critically discuss and comment on which use cases QKD is suited for, considering factors such as implementation complexity, scalability, and long-term security. Our findings contribute to a better understanding of the role QKD could play in future cryptographic infrastructures and offer guidance to decision-makers considering the deployment of QKD.

Paper Structure

This paper contains 63 sections, 2 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Background
  3. Security properties
  4. Confidentiality
  5. Authenticity
  6. Computational and information-theoretical security
  7. One-Time Pads and Message Authentication Codes
  8. Encryption with pre-shared keys
  9. Asymmetric cryptography, PQC
  10. Strengths
  11. Challenges
  12. Assumptions of classical cryptography (including PQC)
  13. Quantum Key Distribution
  14. Assumptions about QKD
  15. Types of QKD service
  16. ...and 48 more sections

Figures (2)

  • Figure 1: Overview of systems involved in the encryption of data using QKD keys. Different types of service provide different functionality and determines which systems the user is required to operate.
  • Figure 2: General architecture of an optical network supporting QKD. Protocol stacks of classic optical network (top-left) and QKD network (bottom-left).