Quantum secure direct communication network with Einstein-Podolsky-Rosen   pairs
  We discuss the four requirements for a real point-to-point quantum secure direct communication (QSDC) first, and then present two efficient QSDC network schemes with an N ordered Einstein-Podolsky-Rosen pairs. Any one of the authorized users can communicate another one on the network securely and directly. 
Fu-Guo Deng, Xi-Han Li, Chun-Yan Li, Ping Zhou, and Hong-Yu Zhou