The three objectives of encryption are:
(1) Assuring privacy/confidentiality of information during transmission.
(2) Assure that messages and digital sig- natures have not been tampered with.
(3) Verifying the authenticity of the source of the message*.
* While this is an objective of encryption, this is only possible with private
key cryptography, where a secret key is shared between the parties. Public
key encryption does not, automatically, provide authenticity because the key
used for encryption is publicly available. More on this later.
Introduction to Encryption