| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To restore encrypted contents when a device gets a trouble even if a master key encrypting a content key is used for a peculiar one for the device. <P>SOLUTION: In an encryption/decoding processing section 110 having a reading preventive function from the outside, the content key Kc used for encrypting contents is encrypted by using the master key Km used for a decoding in the encryption/decoding processing section 110 when contents are reproduced and a restoring key Kr not used for the decoding. In the encryption/decoding processing section 110, an encryption content key Kcm encrypted by the master key Km and an encryption content key Kcr encrypted by the restoring key Kr are stored together with encryption contents Dc, and the encryption content key Kcr is transmitted to a content-key restoring device 200 when the decoding of the encryption content key Kcm is brought into an impossible state. The content-key restoring device 200 decodes the received encryption content key Kcr and restores the content key Kc. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
