| 摘要 |
PROBLEM TO BE SOLVED: To prevent illegal use of music data by allowing an encryption device side to generate an encryption key from an extraction key specific to the music data and a secret key used in common independently of a genre of the music data so as to make decryption of encrypted data difficult in the case of encrypting the music data by the encryption key. SOLUTION: Based on original music data (x0, x1-xn), f(x0-xi) is extracted first by unidirectional conversion (f), and an encryption key h=e f(x0-xi), g} is generated by a unidirectional conversion (e) based on the extracted key f(x0-xi) and a secret key (g). Then the original music data (x0, x1-xn) are encrypted by the encryption key (h) to generate encrypted music data D3. Moreover, one karaoke swing along music data D is generated by formatting the encrypted music data D3, the extracted key f(x0-xi)=D2 and music information data D1, and the data D are transmitted to the user via a communication medium such as the Internet and a storage medium such as an optical disk. |
