| 摘要 |
PURPOSE:To attain optimum security control by determining a cipher level in accordance with the degree of secrecy of a file and data, and ciphering the file and the data in conformity to the determined cipher level. CONSTITUTION:When the file 2 is generated newly by a user, whether the file 2 is to be preserved or not is judged by a file preservation judging means 3, and at the time of preserving it, parameter information is collected by a cipher level determining means 5, and the cipher level is determined in accordance with the degree of secrecy of the file 2 on the basis of this parameter information. A ciphering means 6 classified by level ciphers the file 2 in conformity to this cipher level. Then, when the file 2 is ciphered, the ciphering means 6 classified by level preserves a file name, the cipher level and a key by writing those in the key correspondence table 9 of a list file in the same way. After that, a file preserving means 8 preserves the ciphered file 7 in a disk 10. |
