Introduction to Cryptography

Excerpts from ‘The Bletchley Park Training Manual’ (1939)

Since humanity learned to write, we have sought to hide the meaning of our writings from prying eyes. We have used codes and secret languages for millennia. Creating and breaking these codes is known as cryptography, a field that is partly art and partly science.

The first thing to remember in codebreaking is that you need clues. Do not simply dive in, instead search the environment for hints.

When tackling an encrypted source text, remember to look for letter patterns. For example, the most common letter in the English language is ‘E’.

With a little wit and determination, a source text may be decrypted without every part of it being known. Expert code-breakers use contextual clues to work out words and phrases.

Hello friends! It is I, Graves. I have managed to access what’s left of the facility’s mainframe and managed to find a translation record of this Dalek writing system. If you are SURE that you would like to see it, you may access it below.