Copyright protection system, digital information processing apparatus and copyright protection method

A copyright protection apparatus, comprising:

• first encrypting means for encrypting digital information of a work with a first encrypting function,
• encrypted information receiving means for receiving digital information encrypted by the first encrypting function,
• second encrypting means for encrypting the digital information received by the encrypted information receiving means with a second encrypting function,
• a copyright managing server that manages a copyright of the digital information,
• encrypted information transmitting means for transmitting decrypting information to decrypt the digital information encrypted by the second encrypting function to the copyright managing server, and
• receiving means for receiving a decrypting function that decrypts the digital information encrypted by the first encrypting function and second encrypting function from the copyright managing server in response to the decrypting information transmitted from the encrypted information transmitting means.

A copyright protection method, comprising:

• receiving digital information of a work encrypted by a first encrypting function,
• encrypting the digital information with a second encrypting function,
• transmitting decrypting information for decrypting the digital information encrypted by the second encrypting function to a copyright managing server for managing a copyright of the digital information, and
• transmitting from the copyright managing server a decrypting function for decrypting the digital information encrypted by the first encrypting function and the second encrypting function according to the decrypting information.