As depicted in Fig. 4, the handshaking phase is divided into three steps. In the first handshaking step, the master node sends the messages that are prepared in the last phase to the slave node. The slave node tries to authenticate the master node with the proxy credential and the authentication information MN_Rand from the master node. It first decrypts the proxy credential with the public key of the CA server for the digital signature. If the proxy credential is the real one that was signed by the CA server, the slave node should have all the information that is encapsulated in the proxy credential.