| 摘要 |
A cipher processing system is provided for allowing file access while maintaining the integrity without a user being conscious of the difference between files when the user accesses a file in a folder containing both a ciphertext file and a plaintext file. Thus, according to the present invention, if a folder stores both a ciphertext file and a plaintext file, the ciphertext file is attached with identification information (preferably, footer information) indicating that the file is a ciphertext file, so that the plaintext file and the ciphertext file can be differentiated from each other when the files are read. A deciphered file gained by removing identification information from a ciphertext file and deciphering the file is delivered to an upper-level application. If the read file is a plaintext file, decipher processing is not executed on the plaintext file but the plaintext file is passed to the upper-level application program.
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