| 摘要 |
PROBLEM TO BE SOLVED: To surely update encryption key of encryption data without increasing burden of treatment in a magnetic disc device which records encryption data. SOLUTION: In a magnetic disc device having a magnetic disc for recording encryption data, a magnetic head for carrying out read or write of data to the magnetic disc and a record reproduction circuit connected to the magnetic head for carrying out read treatment of data or write treatment of data, the record reproduction circuit has a data refresh function for reading data of the magnetic disc and writing it back in the same place, decodes data read by data refresh operation, encrypts it again by changing encryption key and writes back the encryption data. COPYRIGHT: (C)2010,JPO&INPIT
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