We present a quantum dialogue protocol by using the Greenberger-Horne-Zeilinger (GHZ) state. In this paper, we point out that the `quantum dialogue' communication scheme recently introduced by Nguyen can be eavesdropped on under an intercept-and-resend attack. We also give a revised control mode to detect this attack. Hence, within the present version two users can exchange their secret messages securely and simultaneously, and the efficiency of information transmission can be successfully increased.
Cite
@article{arxiv.quant-ph/0601127,
title = {Quantum Dialogue by Using the GHZ State},
author = {Yan Xia and Chang-Bao Fu and Shou Zhang and Suc-Kyoung Hong and Kyu-Hwang Yeon and Chung-In Um},
journal= {arXiv preprint arXiv:quant-ph/0601127},
year = {2007}
}