# The Enigma Machine

## What is the Enigma Machine and how does it work?

The enigma machine was invented in 1915 by two Dutch Naval officers. The enigma machine was used to encrypt messages, and decrypt them again later.

The enigma machine worked by changing each letter that was typed in on the keyboard to a random letter, based on the settings of the different rotors and plugs. The new letter would appear on the lampboard for the user to write down. Eventually they would have a completely random message, that no one would be able to understand without decoding it first.

To be abe to decode the message accurately both enigma machines, the machine that encrypted the message and the machine decoding the message, must have the same rotor and plug settings.

## How was Enigma used in World War Two

The German military used the enigma machines to encrypt messages that they would then send to the troops by morse code. Once the troops recieved the encrypted messages, they would decode them using their enigma machine.

During the war the Poles began to intercept the encrypted messages sent by the Germans. They hired mathematicians such as Marian Rejewski to try and crack the codes. Rejewski built a working model of the enigma machine to use to decode the meesages. The mathematicians would try every combination of settings until they found the one that worked.

However Rejewski later discovered that the Germans changed the enigma's rotor and plug settings daily. He, along with the other mathematicinas, would not be able to decode the intercepted messages without knowing the daily key.

## The Bombe

Marian created a machine called the Bombe, which enabled him to test six different settings for the enigma machine, at the same time. This meant he was able to work out the settings for each day much quicker than before. The message would be put into the Bombe and the different sets of drums (rotor replicas) would spin around testing every combination of settings. This would continue until one of the settings decoded the message accurately and so that it made sense. When this was found, the settings of the enigma machines were known for that day.

When the Poles seeked help from their allies, the British and French, the British smuggled replicas of the enigma machines out of Poland two weeks before Poland was invaded by the Germans. When the machines arrived in Britian they were taken to Bletchly Park. Alan Turing, a British mathematician who worked at Bletchley Park, created a new version of the Bombe. This version had 36 enigma machines connected together. This meant the new Bombe was able to work out the enigma machine's settings even faster.

## The Lorenz Cipher Machine

The Lorenz cipher machine was used by the German High Command during World War Two. It was very similar to enigma, except it consisted of 12 rotors instead of 3. This meant it would be even harder for the enimies to decipher the messages, so it was used for important messages to and from the higher ranks.

## Colossus

British engineer, Tommy Flowers, created Colossus in 1943. Colossus was the first ever electronic digital computer that was programmable. The Colossus computer was used by the British code breakers at Bletchly Park during World War Two. Colossus was able to decode the Lorenz cipher that was being used by the German High Command to send encrypted high-level telegraphic messages. Without Colossus, the Allies would not have obtained valuable intelligence information.

Colossus was able to read paper tapes, which contained binary codes, of the encrypted messages and proccess them. To decode the message accurately, and into German text, the settings on Collosus would change until they found the correct settings that matched those of the Lorenz cipher machine. The German text could then be translated into English.