The Enigma Code

How It Works & What It Was Used For

The Enigma Code played a massive part in World War Two. The Germans invented the Enigma Machine which could create codes using the letters of the alphabet and changing them into a different letter of the alpabet. By using Enigma an army could make decisions in secret without the enemy finding out. In WW2 the Enigma Machines were very useful because when they decrypted the enemy codes the British could find out enemy positions and major decisions made.

The machine has several variable settings that affect the operation of the machine. The user must select three rotors from a set of rotors to be used in the machine. A rotor contains one-to-one mappings of all the letters. The other variable element in the machine is the plug board. The plug board allowed for pairs of letters to be remapped before the encryption process started and after it ended.


As the current passes through each component in the Enigma machine, the letter gets remapped to another letter. The plug board performed the first remapping. If there is a connection between two letters, the letters are remapped to each other. After the plug board, the letters are remapped through the rotors. Each rotor contains one-to-one mappings of letters but since the rotors rotate on each key press, the mappings of the rotors change on every key press.


In order to decrypt a message, the receiver must have the encrypted message, and know which rotors were used, the connections on the plug board and the initial settings of the rotors. To decrypt a message, the receiver would set up the machine identically to the way the sender initially had it and would type in the encrypted message. The output of typing in the encrypted message would be the original message. Without the knowledge of the state of the machine when the original message was typed in, it is extremely difficult to decode a message.


The Enigma cypher was the backbone of German military and intelligence communications. The German military, were quick to see its potential.

They thought it to be unbreakable, and not without good reason. Enigma's complexity was bewildering. The odds against anyone who did not know the settings being able to break Enigma were a staggering 150 million million million to one.


During World War Two, Bletchley Park, in Buckinghamshire, played a big part in decrypting the Engima Codes. Without Bletchley Park the course of the war would have been uncertian and could have possibly lasted for another two years. Most of the code breaking and decryptingin Bletchley Park took place in Huts 3, 6, 4 and 8 where the highly effective Enigma decrypt teams worked. The huts operated in pairs and, for security reasons, were known only by their numbers. They recieved the information from the 'Y' Stations many wireless intercept stations based around Britain and in a number of other countries. These stations listened in to the enemy's radio messages and sent them to Bletchley Park to be decoded and analysed.