Controlled Secure Quantum Dialogue Using a Pure Entangled GHZ States

Abstract

We present a controlled secure quantum dialogue protocol using a non-maximally (pure) entangled Greenberger–Horne–Zeibinger (GHZ) states at first, and then discuss the requirements for a real quantum dialogue. We show that the authorized two users can exchange their secret messages after purifying the non-maximally entangled GHZ states quantum channel unconditionally securely and simultaneously under the control of a third party.