Importance

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Abstract

A copyright protection system includes a recording device and a reproduction device. The recording device writes encrypted content, an encrypted content key for decrypting the encrypted content, and license information on a recording medium on which a unique media number has been recorded in an unrewritable state. The license information is generated using both the media number and the encrypted content key, and therefore reflects both values. The reproduction device reads the media number, the encrypted content key, and the license information from the recording medium, and judges whether the license information reflects both the media number and the encrypted content key. The reproduction device decrypts the encrypted content key, and decrypts the encrypted content using the content key only if the license information reflects both values. Thus, the copyright protection system allows only original recording media to be reproduced, and prohibits reproduction of copy recording media.

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First Claim