A effective key management method for secure scada communication

PURPOSE: It can be created the root key to the tree structure and by storing the root key shared key to the root node the key managing method can communicate to the remote terminal or the node in which the word comes under to oneself through the shared key. CONSTITUTION: It is created a plurality of secret keys and the master terminal respectively assigns to the remote terminal(23). The master terminal(21) is created the root key to the tree structure. The leaf node of the tree structure is corresponded to each remote terminal. It hashes the shared keys of all child nodes and the shared key of each node of the root key becomes. The shared key to the root node is a message received from the node corresponding to the remote terminal or the word(22) is oneself and it stores.