For being able of handling concurrent multiple requests from the master node the CA server adopts the technique of multitasking. After setting up the SSL connection with the master node, the CA server creates a new thread to deal with the further requests from the master node. By finishing the reading of the information in the request message, the CA server generates a random message and species the life period for the public key of the master node as well as the expiration time of the SSON certificate in GMT. After that the CA server calls the signature method of Proxy Credential in the Security Module to create and digitally sign the key.