There have always been secrets. And people have been trying to protect their intellectual property from prying eyes for almost as long. For example, the Roman general Julius Caesar used a code for his military correspondence by substituting each letter for the letter three places after it in the alphabet. That turned the word Caesar into Fdhvdu. This simple and – from today’s perspective – insecure form of encryption is a good way of illustrating the basic principles of cryptology.
The point of encryption is to convert plain text, which is easily readable, into a secret text comprising an indecipherable character string. It always includes one or more keys to facilitate encryption and decryption. In the example above, it was the number three representing the number of places the characters shifted.
Since then, this basic form of encryption has been replaced by highly complex technologies and algorithms. But all the different types can usually be divided into two categories: symmetrical encryption and asymmetrical encryption. In practice, companies also often use hybrid encryption.