Patent ID: 8370627

Claim:
In a confidential communication method of messages transmitted and received between a transmission source client that is a subordinate of one communication server of a plurality of communication servers, and a transmission destination client that is a subordinate of another communication server of the plurality of communication servers, wherein the transmission source client and the transmission destination client are connected to a loop network which forwards a message on a basis of a predetermined rule, and in the confidential communication method of the messages, the transmission source client creates first confidential address information including a hash value of a generated random bit string, and a code string obtained by encrypting the random bit string using a public key of the transmission destination client, and second confidential address information including a code string obtained by encrypting the random bit string using a public key of the another communication server to which the transmission destination client connects, and the hash value, and forwards a message including at least the first confidential address information, the second confidential address information, and a message body, to the loop network via the one communication server.