Security of Plug-and-Play QKD Arrangements with Finite Resources

TL;DR

This paper analyzes the security of passive plug-and-play quantum key distribution (QKD) systems with finite resources, considering an untrusted source and optimizing parameters to maximize secure key rate under collective attacks.

Contribution

It provides a comprehensive security analysis for plug-and-play QKD with finite keys, including optimization strategies for decoy states and detailed numerical simulations.

Findings

Secure key rate equations for finite resources are derived.

Optimization of signal-to-decoy ratio enhances key rate.

Security analysis accounts for full channel eavesdropper access.

Abstract

The security of a passive plug-and-play QKD arrangement in the case of finite (resources) key lengths is analysed. It is assumed that the eavesdropper has full access to the channel so an unknown and untrusted source is assumed. To take into account the security of the BB84 protocol under collective attacks within the framework of quantum adversaries, a full treatment provides the well-known equations for the secure key rate. A numerical simulation keeping a minimum number of initial parameters constant as the total error sought and the number of pulses is carried out. The remaining parameters are optimized to produce the maximum secure key rate. Two main strategies are addressed: with and without two-decoy-states including the optimization of signal to decoy relationship.