# High-efficiency three-party quantum key agreement protocol with quantum dense coding and Bell states

## TL;DR

This paper introduces a secure and efficient three-party quantum key agreement protocol that leverages Bell states and quantum dense coding to enhance security and efficiency in quantum communication.

## Contribution

It presents a novel three-party protocol combining Bell states and dense coding, improving efficiency and security over existing methods.

## Key findings

- High efficiency demonstrated through protocol design
- Resistant to both outside and inside attacks
- All participants can derive the same shared key simultaneously

## Abstract

We propose a high-efficiency three-party quantum key agreement protocol, by utilizing two-photon polarization-entangled Bell states and a few single-photon polarization states as the information carriers, and we use the quantum dense coding method to improve its efficiency. In this protocol, each participant performs one of four unitary operations to encode their sub-secret key on the passing photons which contain two parts, the first quantum qubits of Bell states and a small number of single-photon states. At the end of this protocol, based on very little information announced by other, all participants involved can deduce the same final shared key simultaneously. We analyze the security and the efficiency of this protocol, showing that it has a high efficiency and can resist both outside attacks and inside attacks. As a consequence, our protocol is a secure and efficient three-party quantum key agreement protocol.