Security of direct communication quantum channel with feedback

TL;DR

This paper proposes a secure direct quantum communication protocol where feedback and basis masking prevent eavesdroppers from reconstructing the coding basis, ensuring unconditional security.

Contribution

It introduces a novel quantum communication protocol utilizing feedback and basis masking to achieve unconditional security against eavesdropping.

Findings

The protocol prevents Eve from reconstructing the coding basis.

Feedback from the recipient enhances verification capabilities.

The method guarantees unconditional security of the quantum channel.

Abstract

In the direct communication quantum channels the authorized recipient (Bob) and the non-authorized recipient (Eve) have different abilities for verification of received information. Bob can apply the feedback to commit the sender (Alice) to perform verification. Eve has to use for verification an indirect method based on the measurement of a set of incompatible observables enough for determination of the coding basis used by Alice. In the protocol of direct communication regular modification of coding basis and masking it with an equilibrium in average information carrier density matrix prevents reconstruction of coding basis by the results of Eve's measurements of an arbitrary set of observables. This provides unconditional security of the channel.