Only the encrypted file should be transferred from the network. So, that only the cypher text can be viewed when someone is trying the access any of the packets.
Use of VPN:
A separate tunnel is made to have a communication through the internet which is called Virtual Private Network. VPN avoids the unauthorized access to the network. It ensures authentication, integrity, confidentiality, and access control.
As firewall is the first line of defense for network, it prevent intruders from gaining access to the network. It checks the incoming and outgoing traffic to and from the network and blocks on both directions as per the rules defined on it.
Use of SSL (Secure Socket Layer):
It creates a secure connection between staff’s web browser and server of national data center. By encrypting all the information which is send through web browser, it ensures data confidentiality.