Resource requirements and speed versus geometry of unconditionally secure physical key exchanges

TL;DR

This paper analyzes the resource requirements, speed, and reliability of different network geometries for unconditionally secure key exchange, focusing on practical star networks and comparing them with other configurations.

Contribution

It introduces a protocol and equation for secure bit exchange in star networks and explores trade-offs in network geometry for secure key distribution.

Findings

Star networks can be cost-effective for secure key exchange

Trade-offs exist between resource use and speed in different geometries

Reliability varies across network configurations

Abstract

The imperative need for unconditional secure key exchange is expounded by the increasing connectivity of networks and by the increasing number and level of sophistication of cyberattacks. Two concepts that are information theoretically secure are quantum key distribution (QKD) and Kirchoff-law-Johnson-noise (KLJN). However, these concepts require a dedicated connection between hosts in peer-to-peer (P2P) networks which can be impractical and or cost prohibitive. A practical and cost effective method is to have each host share their respective cable(s) with other hosts such that two remote hosts can realize a secure key exchange without the need of an additional cable or key exchanger. In this article we analyze the cost complexities of cable, key exchangers, and time required in the star network. We mentioned the reliability of the star network and compare it with other network geometries. We also conceived a protocol and equation for the number of secure bit exchange periods needed in a star network. We then outline other network geometries and trade-off possibilities that seem interesting to explore.