Defining Security in Quantum Key Distribution

2025/09/16 by Carla Ferradini, Martin Sandfuchs, Ferradini, Carla +5 · 1 voice · 1 citation
Computer Science · Physics and Astronomy · #Advanced Statistical Modeling Techniques #Quantum Information and Cryptography #Quantum Mechanics and Applications #cs.CR #quant-ph

paper · pdf · doi:10.48550/arxiv.2509.13405

openalex publication_date 2025/09/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

The security of quantum key distribution (QKD) is quantified by a parameter ε>0, which -- under well-defined physical assumptions -- can be bounded explicitly. This contrasts with computationally secure schemes, where security claims are only asymptotic (i.e., under standard complexity assumptions, one only knows that ε → 0 as the key size grows, but has no explicit bound). Here we explain the definition and interpretation of ε-security. Adopting an axiomatic approach, we show that ε can be understood as the maximum probability of a security failure. Finally, we review and address several criticisms of this definition that have appeared in the literature.

Citations

• The debate over QKD: A rebuttal to the NSA's objections
• Are quantum cryptographic security claims vacuous?
• Is the security of quantum cryptography guaranteed by the laws of physics?
• Quantum cryptography: Public key distribution and coin tossing
• True randomness from realistic quantum devices
• Incompleteness and Limit of Quantum Key Distribution Theory
• Unconditional Security In Quantum Key Distribution
• Security of Authentication with a Fixed Key in Quantum Key Distribution
• Device-Independent Quantum Key Distribution with Commuting Measurements
• A Proof of the Security of Quantum Key Distribution
• A method for obtaining digital signatures and public-key cryptosystems

Cited by

• Randomness from causally independent processes

Discussions

• I think this is a very misleading figure. The consensus is that RSA will be broken with proba 1 once a quantum computer is available, but I don't think anybody reasonably expects that all postquantum [bsky, 11 points, 2 comments]

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