| 摘要 |
PROBLEM TO BE SOLVED: To designate an indication destination by means of a name, a position and a post, etc., by efficiently and appropriately ciphering personal information and shared information of plural users by the same means. SOLUTION: When specified relation is satisfied by a destination list 102 received from a terminal 202 and user identifying information 106, an IC card 230 returns a group key 103 based on the destination list 102 and a master key 107. The terminal 202 generates a cipher sentence 104 from a ordinary sentence 100 and a data key 101 and a dipher sentence key 105 from the data key 101 and the group key 103 so as to collectively store the destination list, the cipher sentence key and the cipher sentence in a storage device 211. The terminal 203 reads them from the storage device 211 and transmits only the destination list 102 to the IC card 231. The IC card 231 returns the group key 103 to the terminal 203 after this processing. The terminal restores the data key 101 from the cipher sentence key 105 and the group key 103 and decodes the cipher sentence by the data key 101. |
