Brief Introduction to Provable Security

The primary goal of cryptography is to enable parties to communicate securely over an insecure channel, which may be under the control of an adversary. Though originally used mainly for the purpose of protecting the privacy of messages, cryptography now encompasses many other goals, such as guaranteeing the integrity of messages being exchanged or the authenticity of the sender. For most of its history, cryptography was essentially a game played between designers and attackers in which one side would try to outsmart the other by conceiving ad hoc attack and defense mechanisms for their particular goals [Bel11]. Although this ad hoc aspect may always be present in the field, cryptography has since become a well established science, with clear security definitions and objectives. The exact security objectives in which one might be interested will be determined by the application one has in mind and may depend on many factors, such as how powerful adversaries may be or the type of information that needs to be protected. The two most common goals usually considered are data privacy and authenticity. While the goal of data privacy is to keep unintended parties from learning the contents of the message being sent over the channel, data authenticity aims at guaranteeing that the contents of the message have not been tampered with during the course of transmission.