A method allowing communication to be performed in an open environment, the method being performed by an electronic communication system that includes an initiating client , an initiating server , a responding client and a responding server , wherein the initiating client is a local communication device and is used by an initiating user that has an initiating account administrated by the initiating server as a server computer, the responding client is another local communication device and is used by a responding user that has a responding account administrated by the responding server as a server computer, the initiating server , the responding server , the initiating client and the responding client are connected to communication networks, each of the initiating server , the responding server , the initiating client and the responding client has a private-public key pair, the initiating server has a unique name assigned and registred with authorities for making connection to the initiating server , and the responding server has a unique name assigned and registered with the authorities for making connection to the responding server ; wherein, the method comprises the steps of: the initiating client providing an initiating client's public key of the initiating client's private-public key pair to the initiating server by making connection to the initiating server using the initiating server's unique name; the responding client providing a responding client's public key of the responding client's private-public key pair to the responding server by making connection to the responding server using the responding server's unique name; upon communication request by the responding server , the initiating server providing the initiating client's public key to the responding server ; the responding server authenticating the initiating client with the initiating client's public key, and if authentication succeeds, the responding server continuing communication between the responding server and the initiating client ; upon communication request by the initiating client , the responding server providing the responding client's public key to the initiating client ; and the initiating client authenticating the responding client with the responding client's public key, and if authentication succeeds, the initiating client continuing communication between the initiating client and the responding client . the initiating client providing an initiating client's public key of the initiating client's private-public key pair to the initiating server by making connection to the initiating server using the initiating server's unique name; the responding client providing a responding client's public key of the responding client's private-public key pair to the responding server by making connection to the responding server using the responding server's unique name; upon communication request by the responding server , the initiating server providing the initiating client's public key to the responding server ; the responding server authenticating the initiating client with the initiating client's public key, and if authentication succeeds, the responding server continuing communication between the responding server and the initiating client ; upon communication request by the initiating client , the responding server providing the responding client's public key to the initiating client ; and the initiating client authenticating the responding client with the responding client's public key, and if authentication succeeds, the initiating client continuing communication between the initiating client and the responding client . <EOS>