# Quantum cryptography as a retrodiction problem

## TL;DR

This paper introduces a quantum key distribution protocol based on the Mean King retrodiction problem, demonstrating security against advanced attacks and linking retrodiction concepts with quantum cryptography.

## Contribution

It presents a novel QKD protocol leveraging retrodiction, specifically the Mean King problem, and proves its security in ideal conditions against coherent attacks.

## Key findings

- Secure against coherent attacks in error-free transmission
- Utilizes a two-way quantum channel for key distribution
- Establishes a link between retrodiction and quantum cryptography

## Abstract

We propose a quantum key distribution protocol based on a quantum retrodiction protocol, known as the Mean King problem. The protocol uses a two way quantum channel. We show security against coherent attacks in a transmission error free scenario, even if Eve is allowed to attack both transmissions. This establishes a connection between retrodiction and key distribution.