An ideal requirement in the transfer of data from one machine to another machine is that data integrity and confidentiality is maintained and both the sender and recipient can be authenticated. The integrity of the data is maintained only in benign environments in the presence of random errors on unreliable networks. These protocols cannot ensure the integrity of data in the presence of deliberate attacks. The only way to address these problems in an exposed network is to use cryptography.
Encryption is applied to both the control and data channels.