HOW THE ENIGMA MACHINE WORKS:

The enigma machine had one of the most complicated encrypting systems
of that time. This encrypting system used a number of rotors to scramble
the electrical signals (representing letters) that were passed through the
machine. It has places for three different rotors. Early on there were five
to choose from, but later in the war, the Germans added a sixth one making
it even harder to crack. Each of these rotors had 26 electrical contacts on
each side. Each of the electrical contacts on the first side of the rotor
was connected to a single contact on the other side, such that this second
contact stood for a different letter (eg “W” to “A”). Typing of each letter
in the signal to be encrypted or decrypted caused an electrical current to
pass through all the rotors. While signals were being typed, the current
also turned the rotors at different speeds, one fast one slow and one in
the middle. This was all part of the scrambling process.


The operator would put the letter ‘A” into the machine for example, on
the very same rotor it would be changed to “H” the connected contact on
rotor 1. Then going to the second rotor it would be changed to “F” which at
the time would be alined to “H”. The “F” would then be changed to the
connected contact on rotor 2 and then be passed on to the aliened letter on
rotor 3 eg “P”. The “P” would be changed to the connected contact so it may
come out as “G”.

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Now comes the ultimate bit – the German Enigma machine had a reflector
on it which sent the encrypted letter back through the machine further
encrypting it. The reflector worked with 13 pairs of letters. “G” would be
changed to its paired number for example “X”, the whole thing would work
again, and the letter would be changed all over again. The moving Rotors
also meant that if a word contained two of the same letter’s for Attack the
two T’s could turn out to be A and V making the message even harder to
crack. The Germans changed the Rotor numbers and starting positions
everyday.


The machine had two sets key boards one to type the message and one
which had light’s under it. The light’s showed the letter which the
original letter had been encrypted to. The operator had to write these down
so he would know what to send with Morse code.


THE STEPS INVOLVED IN CRACKING THE CODE AND A GENERAL OVERVIEW OF HOW ALL
BEGAN:
After its defeat in the First World War, the German defence force
wanted to improve the security of communication in the German armed forces.

The answer came when Dr Arthur Scherbius developed an enigma machine. He
set up a company in 1923 in Berlin and called it the Chiffriermaschinen
Aktiengesellschaft (cipher machines corporation) in the hope large;
companies would be interested in them for secure communication. The German
saw the enigma machine and three years later, the German navy was making
their own enigma machines and the army and air force soon followed. The
machine was improved over the years.


The allied code breakers got there first look at what they were up
against when a German spy allowed his French spy masters to photograph
stolen enigma manuals. The Polish cipher bureau made the first big step
they managed to reconstruct an enigma machine. They were reading German
messages between 1933 and 1938.


In 1939, the Polish cipher bureau shared its work with the British code
breakers at Bletchley Park in Buckinghamshire. Bletchley Park was one of
the best-kept secrets of the war and it was not revealed what part it had
played until 1974 nearly 30 years after the war had finished. Many
mathematicians and problem solvers were recruited and huge computers called
“bombs” were built to work out the many different enigma settings. Any
information gained on the enigma was known as Ultra and was top secret.

Only very, few knew about what was being done at Betchley Park. It was hope
that the Germans would not know that any of their ciphers had been broken.


It was a while before the work had any impact on the war effort often
better information was gathered by integrating prisoners, aerial
reconnaissance and captured documents. In 1941, a breakthrough was made.

Evidence from reading parts of messages told them of the German in build up
prior to the invasion of Greece. However, the British did not have the
forces to exploit this. Later that year Bletchly Park cracked an Italian
enigma message, this helped Admiral Cunningham’s Mediterranean fleet defeat
the Italians at the battle of Matapan. Later the ciphers used by Rommels
Afrika Korps, were broken now they would know his next move and every
nearly every course his supply ships would take. This was a huge advantage
and turned the battle for Africa in favour of the British.

Bletchley Park now turned its attention onto breaking the U-boat codes.

The U-boats were stoping many supplies from reaching England and it was
hoped that if the code could be broken that supply ships could be kept away
from the danger areas. To do this they had to capture an enigma machine and
its codebooks. In April 1941, the German Trawler “Krebs” was captured.

Along with two enigma machines and a list of the rotor settings rotor
numbers for the next month. For one month the British could read the enigma
messages but with some delay. In May, the Mnchen was captured along with
the setting’s for the month of June. Then the settings for the month of
July were captured now the code breakers at Bletchley Park were reading the
messages almost without any delay.


All these events lead the Germans to try to tighten the security of the
code but all it did was to increase the funding of Bletchley Park. The
Germans then installed a forth Rotor multiplying the number of settings
another 26 times. The resulting game was known to the Germans as “Triton”
and to the British as “Shark” for over a year the British could not
penetrate any further into the enigma. Better computers from the USA helped
the British once again in being able to read the German navel messages
regularly.


The cracking of the enigma played a large part in the outcome of the
war it helped stop Rommel in Africa, the U-boats and many other operations.

The cracking of the Enigma took them the best part of 7 years and even
then, they could not read every message that was sent. The figures shows
that of over 5 million messages intercepted during the war only about 50,00
were ever read that’s less then 1% of messages intercepted.

pic An enigma machine
THE COMPUTER PROGRAM:
This is a Enigma simulator I got off the internet it works exactly the
same way as the real version. It shows the rotors moving and the lights
that come up under the encrypted letter.

First you choose the Rotor numbers I have chosen “6”, “3”, “5” and “4” my
starting positions will be “K”, “S”, “L” and “U”. I then type my message
in.

THE ENIGMA CODE
It comes back scrambled as
APNOY UTAPS FVX

I then set the rotors back to their original position, and type the
encrypted message in
APNOY UTAPS FVX
And I get the message back
THEEN IGMAC ODE
Which comes to
THE ENIGMA CODE.


|Geheim! Secret indeed! This is an example of the setting sheets used. It|
|has the day Rotor number and starting position on it. |
|pic |

pic
Bletchley Park

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