2. About encryption Convert data according to the rule that was the same when I exchange the digital data such as a document or the image through a network.

4. About Firewall I control a particular computer network and communication with the outside, and the fire wall is hardware equipped with software aimed at maintaining the security of the internal computer network or the software.

5. About VPN The service that can use a public line with VPN as if it is a dedicated line. The use with the low cost is possible, but, in a characteristic of the Internet, security and the security of the communication quality become difficult than I use the communications network of the carrier.