| 摘要 |
PROBLEM TO BE SOLVED: To provide encryption management technology which safely manages an encryption key used for encryption and a decoding key which decodes encrypted data. SOLUTION: An encryption terminal Cc extracts an operation log based on a predetermined extraction condition from own operation log, and generates the encryption key. A file is encrypted by the created encryption key, and the encrypted file is transmitted to a decoding terminal Cd together with an encryption specification information. The decoding terminal Cd requests generation of the decoding key based on the encryption specification information to an encryption management server S in order to decode the encrypted file. While the encryption management server requests the generation of the decoding key, specifies the encryption terminal Cc based on the encryption specification information, and extracts the operation log of the encryption terminal Cc based on the predetermined extraction condition; it generates the decoding key from the extracted operation log, and transmits it to the decoding terminal Cd. The decoding terminal Cd which obtains the decoding key, decodes the encrypted file by the obtained decoding key. COPYRIGHT: (C)2009,JPO&INPIT
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