To facilitate management of the rights to utilize content, thereby improving safety.
A key generation device 831 generates a set of keys: an encryption key 731 necessary to generate plural encrypted contents by encrypting plural contents for sell by a function type encryption method on the basis of attributes set in the respective contents and a master key necessary to generate a decryption key to decrypt the contents encrypted by using the encryption key 731. A user management device 832 stores in memory the information regarding one or more contents which users have purchased. A decryption key generation device 833 generates a decryption key 733 using the master key generated by the key generation device 831 on the basis of the information stored in memory by the user management device 832, the decryption key 733 having the conditions set therein which enable the users to decrypt with one decryption key the plural encrypted contents generated using the encryption key generated by the key generation device 831, thereby restoring one or more contents the users have purchased.
SAKAGAMI TSUTOMU
YAMANAKA TADAKAZU
NAKAMURA DAISUKE
| JP2009194860A | 2009-08-27 | |||
| JP2006080658A | 2006-03-23 |
| WO2010123122A1 | 2010-10-28 |
CSNG201000981011; 曽我部 靖志: '最近の新聞等で報道された技術情報を深める ニュース解説' 電子情報通信学会誌 第９３巻，第１２号, 20101201, ｐｐ．１０７０-１０７１, 社団法人電子情報通信学会
Yoshihisa Yamazaki