Cryptographic Terminology – A Glossary

Introduction

When reading or hearing about cryptography and cryptology, unless you are a specialist in that field, you probably often encounter words and phrases that are somewhat foreign. With this post I am going to start a lose series of posts trying to explain one term at a time. Starting a series about cryptographic terminology, this post had to be about one cryptographic expression as well and I decided to take a look at the term Cryptography itself.

This post will also act as an anchor point, listing all the other posts in this series as they are written. With that, it will provide a form of Glossary that I am going to reference in later articles.

What is Cryptography?

Cryptography has its origins in the Greek language. It is a compound word with these two parts:

• krupto: I conceal
• grapho: I write

That means cryptography is the art of writing concealed messages.

Nowadays, cryptography is a lot more than just hiding content. Cryptography has evolved into its own field of mathematics with a heavy influx into computer science and for the last few years even physics. The focus of cryptography is to find methods of transformation that are easy to execute but extremely hard to reverse unless you are holding or have access to some kind of secret, commonly referred to as a key.

A method of transformation in this context really is an algorithm that takes some form of input, a text document for example, and produces some form of indecipherable output - an encrypted document. That the output is illegible is certainly not the only requirement. In most cases, there needs to be another algorithm that can turn this document back into its readable form. An algorithm (pair) that can turn a document into a scrambled form and then back is called a cryptographic algorithm or sometimes encryption algorithm. An algorithm is a good cryptographic algorithm, if it is more expensive for an attacker (not knowing the key) to reverse the scrambling than the knowledge of the unscrambled material is worth to the attacker.

Summary

Cryptography is the art of hiding information. It is a field of mathematics and tries to develop algorithms that can scramble information in a way that it is easy for the intended audience to unscramble the message, but very hard for bystanders.

The Glossary

Below is the list of cryptographic terms that I have already covered. I will update it with every new post, starting with this one.