To provide a file system which enables it to improve tamper resistant characteristics in a case that the data with which a single value or single pattern is repeated are set as object of encryption.
A repetition partial detecting section 22 searches whether there exists a repetition portion in the file data passed from a user program 10. If there is a repetition portion, a random value generation section 23 generates a random value, and a repetition partial editorial section 24 changes a repetition portion into a random value. A meta-information storage section 25 stores the meta-information for returning the repeated portion, which has been changed into the random value, to the original value. Furthermore, a control section 21 writes file data and meta-information which are blocked by a data/block conversion section 26 via a block encryption/decryption module 30, into an external storage 3.
TOSHIBA SOLUTIONS CORP
Satoshi Kono
Makoto Nakamura
Kurata Masatoshi
Takashi Mine
Yoshihiro Fukuhara
Sadao Muramatsu
Ryo Hashimoto
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