Phase II: Applying and issuing a proxy credential. To apply and issue a proxy credential, the first step, Phase II(a) in Fig. 3, is to set up a secure connection between the master node and the CA server. The SSL protocol is applied in this phase to provide the secure connection. During the setup of an SSL connection, the master node acts as the client of SSL and the CA server as the server side. According to the flow of the SSL protocol with client authentication, the master node and the CA server are authenticated by each other before any data transmission. After the authentication via the handshaking process of SSL, a secure connection with encryption between them is established.