Continuous Variable Quantum Key Distribution: Finite-Key Analysis of Composable Security against Coherent Attacks

TL;DR

This paper analyzes the security of continuous variable quantum key distribution protocols with finite data, providing bounds on secret key rates under coherent attacks using entropic uncertainty relations, ensuring composable security.

Contribution

It introduces a finite-key security analysis for CV-QKD protocols against coherent attacks using smooth entropies, extending previous results to more general attack models.

Findings

Positive key rates achievable with current experimental parameters.

Security bounds valid under general coherent attacks.

Comparison with bounds under collective attack assumptions.

Abstract

We provide a security analysis for continuous variable quantum key distribution protocols based on the transmission of squeezed vacuum states measured via homodyne detection. We employ a version of the entropic uncertainty relation for smooth entropies to give a lower bound on the number of secret bits which can be extracted from a finite number of runs of the protocol. This bound is valid under general coherent attacks, and gives rise to keys which are composably secure. For comparison, we also give a lower bound valid under the assumption of collective attacks. For both scenarios, we find positive key rates using experimental parameters reachable today.