[Issue] In the cloud server, data is distributed to multiple devices such as data storage devices, data processing devices, and communication devices. Therefore, in order to protect data from unauthorized access, security measures are applied to all of them, which need to be constantly updated. Moreover, this security management depends on the operators of the respective devices, and even if each operator completely performs, it is not possible to predict when a new attack method will be devised, leaving users with a constant data-leakage-related anxiety.
[Methods to solve the Issue] The present invention moves confidential data stored in a cloud server on the Internet to a data storage device of an intranet connected via a firewall, and links the ID of the confidential data and the confidential data. It is thus characterized by not placing confidential data on the internet. As a result, it is possible to narrow the measures for preventing unauthorized access to the firewall, the management becomes easy and the user can take the lead in management, so the user can use the cloud server with peace of mind.