| 摘要 |
PROBLEM TO BE SOLVED: To make a new group cipher-key in common, by dividing the group without performing individual communication from a terminal to the base station in mobile communication. SOLUTION: In mobile communication, when users desire to divide the group by BD(Bermester-Desmedt) method, in the case that they hold a group key in common, the base station issues a direction for making a new group where the group constituent members are the same but only the group ID is different, to the members constituting the group which is the object of division. The base station deletes the group member from each group, according to division conditions, calculates each new group information, and sends the same information to the members. The members in the new group calculate a new group key from the new group information.
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