Key update method and apparatus thereof

摘要

A key update method and a key update apparatus are provided. The method includes storing data in a database of an update server, the data having an encoded updated node key in response to a node key update for a group; selecting necessary data, from among the data having the encoded updated node key, to calculate a key immediately prior to when the member is switched to the online mode, and generating member update data; and performing a key update with respect to the member using the member update data in a device corresponding to the member which has switched from the offline mode to the online mode.