Data communication system

A data communication system comprising:

• an IoT device;
• an information processing device capable of performing communication with the IoT device;
• a service server capable of performing communication with the IoT device and the information processing device;
• and
• a common key management server capable of performing communication with the service server,
• wherein when a coupling request from the IoT device is received, the information processing device requests the common key management server for a tentative common key which is temporarily valid,
• wherein when a request for a tentative common key from the information processing device is received, the common key management server generates a tentative common key and transmits the tentative common key to the information processing device,
• wherein the information processing device transmits the received tentative common key to the IoT device,
• wherein the IoT device and the common key management server perform authentication by using the tentative common key, and
• wherein the service server provides communication service to an IoT device which is authenticated.