# 1. Introduction

**Encryption** is the process of scrambling data in such a way that only legitimate users can read it.

This is what *plaintext* i.e. unencrypted data looks like

**Humpty Dumpty sat on a wall.**

and this is what *ciphertext *i.e. the encrypted version might look like

**jkd2f*hkdfh7$171kjfh7d1h4d**

Encryption works by scrambling the original data using an algorithm and a very large digital number (key). These algorithms involve advanced mathematics and make it difficult or impossible to reconstruct the original data without the correct key.

Encryption can also be applied to 'real-time' streaming data for copy protection purposes. For example only paid-up subscribers are able to access encrypted commercial entertainment streams or satellite broadcast channels.

This section will describe two types of technologies

- Symmetric key encryption
- Assymetric key encryption