Patent ID: 6343281
Filing Date: 2002-01-29
Classification: G11B

Abstract:
A device to be used with digital data copying apparatus for preventing fraudulent copies of a digital data;said digital data containing an encrypted data main body, encrypted copy management information for controlling permission with regard to copying the data main body and key information for decrypting said data main body; said device containing: a determining section for determining if permission be granted for copying digital data or not based on if the copy management information satisfies predetermined requirements or not; and a key altering section for altering said key information contained in said digital data when the determining section determines that permission should not be granted for copying said digital data; and wherein said key information includes a plurality of different keys that are used in common to a plurality of recording mediums, and when the determining section determines a copy-prohibited state of the digital data, the key altering section alters the key information corresponding to the copy-prohibited digital data.