The user session U_Session and the life cycle of the public key MN_Pub are stored on the slave node. U_Session will be used later as authentication information of the current user instance for task assignment and execution on the slave node. The proxy credential is stored on the slave node as well to protect the slave node from replay attacks. All information is maintained on the slave node, until a job-finished message is received from the master node. In this case, the slave node deletes the information.
The first handshaking aims to authenticate the master node by the slave node. In the second handshaking step, the slave node is authenticated by the master node. In addition, the encryption scheme and the corresponding key for later communication are also determined in this step.