TCP/IP connections between clients and servers — especially when
they use the internet — are vulnerable to attack by malicious parties. Protection
is provided in a number of different ways.
Message protection
Message protection is a term that describes the techniques
used to ensure that a confidential message cannot be observed in transit,
and cannot be illicitly changed.
Identification and authentication
Identification is the process by which the identity
of a user is established, and authentication is the process by
which a service confirms the claim of a user to use a specific identity by
the use of credentials (usually a password or a certificate).