| 摘要 |
In a client terminal of a communication system, a cipher session establishing section establishes a cipher session use connection between the client terminal as a source client terminal and a relay server by transmitting/receiving a cipher session establishment message between the source client terminal and the relay server, and notifies header information contained in a cipher session header to the relay server. A shared key managing section holds a client shared key with a destination client terminal, A data enciphering section performs encipherment of a data and/or MAC (Message Authentication Code) calculation of the data by using the client shared key and to output the performing result as a client cipher data. A message producing section produces a data communication message including a cipher data field in which the client cipher data is inserted and a non-cipher data field in which the cipher session header containing the header information is inserted. A transmitting section transmits the data communication messages destined to the destination client terminal to the relay server by using the cipher session use connection. |
