Multiparty controlled quantum secure direct communication using Greenberger–Horne–Zeilinger state

Based on the idea of dense coding of three-photon entangled state and qubit transmission in blocks, we present a multiparty controlled quantum secret direct communication scheme by using Greenberger–Horne–Zeilinger state. In the present scheme, the sender transmits three bits of secret message to the receiver directly and the secret message can only be recovered by the receiver under the permission of all the controllers. All three-photon entangled states are used to transmit the secret message except those chosen for eavesdropping check and the present scheme has a high source capacity because Greenberger–Horne–Zeilinger state forms a large Hilbert space.