| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To reduce the number of pieces of transmission of trap doors from an information processing apparatus to a server device, and to perform data retrieval to a retrieval request from a user within a range permitted to the user. <P>SOLUTION: A group management device 401 issues a key in which permission generation ranges are set for every user of the information processing apparatus 301 while updating the key, the information processing apparatus registers a generation value and encrypted data of the key issued to the user in the server device 201, generates an integrated trap door which integrates trap doors for n (n≥1) generations on which a permission generation range of the user is reflected using the key issued to the user to be transmitted to the server device, the server device derives n trap doors from the integrated trap door, analyzes the respective trap doors, and limits a retrieval range of the encrypted data to the permission generation range of the user to retrieve the encrypted data. The information processing apparatus transmits the integrated trap door in which the trap doors for n generations are integrated, thereby a communication amount with the server device is reduced. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
