Security analysis of the decoy method with the Bennett-Brassard 1984 protocol for finite key lengths

TL;DR

This paper derives a formula for the sacrifice bit-length in the BB84 quantum key distribution protocol using the decoy method for finite keys, enhancing security guarantees and key rates.

Contribution

It introduces a new formula for sacrifice bit-length in finite-key BB84 QKD with decoy states, improving security and key generation rates.

Findings

The formula guarantees security parameters for practical QKD systems.

Numerical evaluations show improved key rates over previous methods.

The method is effective even in asymptotic regimes.

Abstract

This paper provides a formula for the sacrifice bit-length for privacy amplification with the Bennett-Brassard 1984 protocol for finite key lengths when we employ the decoy method. Using the formula, we can guarantee the security parameter for realizable quantum key distribution system. The key generation rates with finite key lengths are numerically evaluated. The proposed method improves the existing key generation rate even in the asymptotic setting.