Three-party quantum secure direct communication based on GHZ states

We present a three-party simultaneous quantum secure direct communication (QSDC) scheme by using Greenberger–Horne–Zeilinger (GHZ) states. This scheme can be directly generalized to N-party QSDC by using n-particle GHZ states. We show that the many-party simultaneous QSDC scheme is secure not only against the intercept-and-resend attack but also against the disturbance attack.