A secure communications scheme should accomplish some or all of the following objectives:
Protect data in transit from eavesdropping by unauthorized parties. This is usually accomplished by encryption by the sender, and decryption by the recipient.
Allow the recipient to detect if the data has been tampered with in transit.
Allow each party to verify the identity of the other.
Prevent the sender later denying that the data was sent, or claiming it had different content.
SSL (secure sockets layer) and its derivative IETF-TLS (transport layer security) provide these facilities by means of public-key encryption. These schemes work at the ‘transport’ layer of communication—that is, they work on raw data and are not concerned what ...