Client apparatus and content processing method in client apparatus, and content provision system

摘要

A client apparatus can protect a content key, which is required for decrypting encrypted content, from a malicious third party. In the client apparatus, an authority managing unit and a content using unit share a session key (distribution key) provided in common to all apparatuses before shipment. Therefore, when the authority managing unit sends a content key to the content using unit, the authority managing unit encrypts the content key with the session key that the authority managing unit itself has. Then, the authority managing unit sends the encrypted content key to the content using unit via a common bus. The content using unit, having received the encrypted content key, decrypts the encrypted content key with the session key, which the content using unit itself also has, to obtain the content key.