Data sending/receiving device and digital certificate issuing method

摘要

A management unit ( 110 ) which issues a digital certificate to a new transmission unit ( 410 ) includes a wireless communication section for performing communication in a network ( 300 ) and a wire communication section to which the new transmission unit ( 410 ) can be connected; when the new transmission unit ( 410 ) is wire-connected to the management unit ( 110 ), it is judged in accordance with the received device type information of the new transmission unit ( 410 ), whether or not the new transmission unit ( 410 ) is a device having a communication means that can communicate in the network ( 300 ); and if the new transmission unit is judged as a device having that type of means, the management unit creates a digital certificate by using a device identifier specific to the new transmission unit ( 410 ), and sends the digital certificate to the new transmission unit ( 410 ).