| 摘要 |
PROBLEM TO BE SOLVED: To make data illegally copied not reproducible by a normal reproducer and to make even normal data not reproducible by an illegal reproducer by ciphering data and overwriting key information on data as a normal mark for releasing the ciphering. SOLUTION: Data to be recorded is ciphered by a ciphering section 2, an error correction code is added by an ECC encoder 3, to make a data block (ECC block). A performing key generating section 8 generates a performing key for ciphering based on common information for certifying license and a session key using random numbers and the like. A disk ID is detected from a pickup, a function value for this ID and ID equipment 11, and ciphering/ decoding are generated by a function value generator 15, a session key is ciphered based on this function value, and key parity is added by an ECC 2 encoder 13. This key data and key parity are overwritten additionally on the ECC block. |
