Authentication is the process of proving on'e identity to someone else. As humans, we authenticate
each other in many ways: we recognize each other's faces when we meet, we recognize each other's voices on the telephone,
we are authenticated by the customs official who checks us against the picture on our passport.
Consider how one party can authenticate another party when the two are communicating over a network.
When performing authentication over the network, the communicating parties cannot rely on biometric information, such
as visual apperance or a voiceprint.
Authentication must be done solely on the basis of messages and data excahanged as part of an authentication
protocol.
