| 摘要 |
PROBLEM TO BE SOLVED: To provide a group key updating method capable of reducing the number of group key update messages to be transmitted and received when updating a group key in a network forming a non-closed path oriented graph topology by plural nodes including a node to be one root node and having a parental relation between nodes in adjacent hierarchies.SOLUTION: In a network forming a non-closed path oriented graph topology by plural nodes including a node to be one root node and having a parental relation between nodes in adjacent hierarchies, the root node creates a list indicating a group key and a first node that is an object for which delivery of the group key is prohibited, and a first child node other than the first node among child nodes of the root node encrypts a decodable group key, so as to transmit a first message including an encryption group key that is a group key encrypted to the first child node and the list. |
