CONTENT DISTRIBUTION SYSTEM, ENCRYPTION UNIT, CONTENT PROVISION UNIT, CONTENT PLAYBACK UNIT, LICENSE INFORMATION PROVISION UNIT, ENCRYPTION METHOD, CONTENT PROVISION METHOD, CONTENT PLAYBACK METHOD, LICENSE INFORMATION PROVISION METHOD, INFORMATION PROCESSING PROGRAM, AND STORAGE MEDIUM

摘要

PROBLEM TO BE SOLVED: To encrypt contents to enhance confidentiality, enabling efficient decryption processing.

SOLUTION: Objects constituting contents are encrypted using different encryption keys. The encryption keys may be modified on an object-by-object basis, or may be set for each group after grouping the objects by object type, etc. Thus, the content can be encrypted portion by portion with different encryption keys. In the above latter case, the objects are encrypted allowing duplication of the encryption keys. The change granularity of the encryption keys is settable. Each encryption key is dynamically generated from one content key Kc and a key generation data being set to the object. The content key Kc is encrypted so as to be decrypted using right information called license, and embedded into the encrypted content.

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