| 摘要 |
<P>PROBLEM TO BE SOLVED: To decrypt an attached file of encrypted electronic mail by tracking decryption key notification mail on an electronic mail transmission system in order to audit electronic mails transmitted to the outside of an organization. <P>SOLUTION: A mail hold server which holds electronic mail transmitted from an internal client to an external client determines whether or not the electronic mail is encrypted electronic mail having an encrypted attached file. If it is encrypted electronic mail, a decryption key wait hold state is set and the electronic mail is registered in a held mail database. It is then determined whether or not the received electronic mail is decryption key notification mail containing a decryption key in the text of the mail. If it is decryption key notification mail, a decryption key in the decryption key notification mail is used as a decryption key candidate to attempt the decryption of the encrypted attached file of the encrypted electronic mail in the decryption key wait hold state. If rightly decrypted, the setting of the decryption key wait hold state is canceled, a state of holding transmission to the external client is set and thereafter, the electronic mail is transmitted. <P>COPYRIGHT: (C)2013,JPO&INPIT |
