An Efficient Controlled Quantum Secure Direct Communication Protocol via GHZ-like States

Based on the GHZ-like state, we proposed a new efficient three-party controlled quantum secure direct communication protocol for the sender to send secret information to the receiver with the permission and assistance of the controller. In this scheme, the controller prepares GHZ-like state and performs random unitary operation on the particles, and the sender encodes secret information onto his particles using dense coding and then transmits them though the quantum channel. The receiver can recover the secret information based on the controller's information and the results of the Bell basis measurement. The operations performed by the controller ensure that the receiver cannot obtain any part of the secret information without the permission of the controller. In addition, it is proved that the efficiency of the proposed scheme is higher than the existing protocols by comparison.