Data integrity verifies that the data has not been altered on the trip between the sender and the receiver. A field calculated by the sender is recalculated and verified to be the same by the receiver. Passwords and authorization maintain control over who has access to personal data. Redundant devices and links attempt to provide 99.999% availability to users. Integrity is made possible by requiring validation of the sender, not the destination. VPNs are not the only secure method by which data can be transferred confidentially.