  In this paper, a three party controlled quantum secure direct communication
protocol based on GHZ like state is proposed. In this scheme, the receiver can
obtain the sender s two secret bits under the permission of the controller. By
using entanglement swapping, no qubits carrying secret messages are
transmitted. Therefore, if the perfect quantum channel is used, the protocol is
completely secure. The motivation behind utilizing GHZ like state as a quantum
channel is that if a qubit is lost in the GHZ like state the other two qubits
are still entangled. The proposed protocol improves the efficiency of the
previous ones.
