| 摘要 |
There is provided a content use management method capable of preventing unauthorized distribution of a content and improving user-friendliness. In this method, the same group key is stored in a secure device ( 400 ) and a playback terminal ( 500 ). Moreover, a license issuing application is received from a license distribution server ( 200 ) and stored in the secure device ( 400 ). After this, a license encrypted by the group key is sent to the playback terminal ( 500 ) and the license encrypted by the group key is stored in the playback terminal ( 500 ). Upon playback of the encrypted content, the playback terminal ( 500 ) decrypts the license by using the group key and acquires the content decryption key, thereby decrypting the encrypted content. Even when the encrypted license flows into the network, it cannot be decrypted by a playback terminal not having the same group key and the copyright is protected. Moreover, the playback terminal ( 500 ) which already holds the group key and the license encrypted by the group key does not need the secure device when reproducing the encrypted content.
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