Armstrong, Westerman, Hattori, McLeland & Naughton
Data copyright management method
 The present invention provides a process for managing data copyright in the case when a primary user produces new data by editing a plurality of original data which have been supplied from data broadcasting, a recording medium or a database, and supplies the new data to a secondary user. A public-key and a private-key of the primary user, and a first secret-key and a second secret-key of the original data, each of which is controlled by a copyright management center, and an edit program are used. The primary user, who is supplied a plurality of original data encrypted by each first secret-key thereof, decrypts the plurality of original data by each of the secret-keys and produces new data using the edit program. The primary user re-encrypts the new data by the second secret-key of each original data, respectively. The re-encrypted data is supplied to the secondary-user, together with editing process data which includes a digital signature generated using the private-key. The secondary user presents the editing process data with the digital signature to a copyright management center. The copyright management center confirms that the digital signature is of the primary user, and then, transmits the second secret-key for the respective original data. In the present data copyright management process, it is possible that the secondary user edits again the data which has been edited, by using the second secret-key in place of the first secret-key and using a third secret-key in place of the second secret-key. 
Mitsubishi Corporation
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Makoto
Saito