| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication controller that can properly select an object of certificate by a digital signature and exchange information with an external party with security, while each client needs not manage data for encryption and decoding, the digital signature and its authentication and a terminal of an operation object need not to be specified. SOLUTION: When client machines 3a-3d transmit a mail expression or the like to a transmission server 1, the transmission server 1 uses a destination public key to encrypt the mail and applies a digital signature to the mail by using a private key decided on the basis of a transmission rule parameter. Then the transmission server 1 transmits the encrypted mail expression and the digital signature or the like to a reception server 2. After authenticating the digital signature of the received mail, the reception server 2 transmits the mail to client machines 3a-3d. However, the mail is aborted in agreement with conditions of a delivery rule parameter. Furthermore, by using the private key of a recipient and/or a department to which the recipient belongs, the encrypted expression in the mail is decoded. |
