Methods of confidential data sharing and mutual authentication between a sensor node and a router are established, and data in the sensor node is protected from a physical attack. Sensor node issuing processing is performed on a sensor node having a tamper resistant device. The sensor node issuing processing is processing in which data and a function that are deactivated are loaded in the tamper resistant device of the sensor node from the time of manufacture of the sensor node to the time the sensor node reaches a system that runs the sensor node. Activation data is used to activate the deactivated data and function. The activation data is shared between stages of the issuing processing with the use of a data management system.