Deterministic Secure Direct Communication Using Ping-pong protocol without public channel

TL;DR

This paper introduces a deterministic secure direct communication protocol using EPR pairs that does not require a public channel, ensuring security against eavesdropping through Bell basis measurements.

Contribution

It presents a novel protocol utilizing EPR pairs for secure direct communication without the need for a public channel, enhancing security and simplicity.

Findings

Eavesdropping attempts disturb the EPR pairs, revealing Eve's presence.

The protocol allows secure message transmission with asymptotic security.

No public channel is required for the communication process.

Abstract

Based on an EPR pair of qubits and allowing asymptotically secure key distribution, a secure communication protocol is presented. Bob sends either of the EPR pair qubits to Alice. Alice receives the travel qubit. Then she can encode classical information by local unitary operations on this travel qubit. Alice send the qubit back to Bob. Bob can get Alice's information by measurement on the two photons in Bell operator basis. If Eve in line, she has no access to Bob's home qubit. All her operations are restricted to the travel qubit. In order to find out which opeartion Alice performs, Eve's operation must include measurements. The EPR pair qubits are destroyed. Bob's measurement on the two photons in Bell operator basis can help him to judge whether Eve exist in line or not. In this protocal, a public channel is not necessary.