Patent ID: 8060746

Claim:
An e-mail transfer method of an e-mail transfer device for transferring an e-mail by a public key encoding method between an e-mail transmission device and an e-mail reception device comprising: receiving from the e-mail transmission device a trigger message to which user authentication data and a public key are added; authenticating the user authentication data; assigning a trust assignment identifier to the public key within the trigger message to be transmitted to the e-mail reception device and triggering a response message to be transmitted by the e-mail reception device when the user authentication data within the trigger message are authenticated by the authenticating; receiving from the e-mail reception device the response message to which user authentication data and a public key are added; and assigning a trust assignment identifier to the public key within the response message to be transmitted to the e-mail transmission device and triggering the e-mail to be transmitted to the e-mail reception device by the e-mail transmission device when the user authentication data within the response message are authenticated by the authenticating, wherein the e-mail transmission device transmits the trigger message to the e-mail transfer device, acquires from the e-mail mail transfer device the response message from the e-mail reception device, verifies whether or not the trust assignment identifier is assigned to the public key within the response message, and transmits to the e-mail reception device an e-mail electronically signed with a private key of the e-mail transmission device and encoded with a public key of the e-mail reception device to which the trust assignment identifier is assigned when it is verified that the trust assignment identifier is assigned to the public key within the response message.