In post-World War I Europe, secrecy
between paranoid nations becomes paramount. The growth of international commerce
creates a need for companies to keep their information secret from
competitors. Germany’s Arthur Scherbius develops the
Enigma machine as a means of keeping those business transactions secure. It
works by generating an electric current when a letter key is pressed. A number of
moving mechanical parts then scramble the path of the current, producing a
different letter each time the key is pressed. The Enigma machine is about to become
the German Army’s most powerful code making weapon in World War II, a weapon they’re
confident can keep their secret military codes secret. Arthur Scherbius had invented a machine
which, if you gave the machine to the enemy, even if you gave the machine to
the enemy, there would be so many complications, so many possibilities, that
you could not in reasonable time decipher the message. Just like Alberti’s
code wheel, the Enigma machine creates multiple poly alphabetic substitution
ciphers. It’s fast, it’s mechanized, and it produces codes that seemed unbreakable. It’s a device for turning readable
messages into unreadable messages. Given an enigma machine with an unknown set of
wheels, the enemy has to consider that that machine can be set up in one
hundred and eighty six million million million ways. The millions of
permutations are achieved by the number of variables involved when setting up the
machine. At the height of the war, German operators changed these settings every
day. They placed the rotors in a specified order from left to right. The rings that
allow the rotors to turn are repositioned daily, as is the patch panel of cables
electrically linking one letter to another. These variables made the Enigma encryption virtually immune to frequency analysis.
The germans think their Enigma code uncrackable. They believe no one has
enough time, or the mathematical ability, to work through the millions of
combinations. A coded message is created by typing the German plain text into the
machine, and then having the encrypted message transmitted via Morse code. In September 1939, Nazi coded messages
flood the radio airwaves at the same time British military intelligence is in
the process of setting up the secret place in wartime Britain, a place tn hopes can
crack the Enigma code. Bletchley Park, 50 miles north of London, becomes
known as Station X. It’s staffed by a handpicked team of
mathematicians and graduate scholars, including Alan Turing, one of the
founding fathers of modern computing. Turing and his team are under extreme pressure
to come up with some way, either mathematical or mechanical, to crack the Enigma code. By 1945 German u-boats are sinking
thousands of tons of Allied supply ships in the North Atlantic. The U-boats are
receiving their orders by Enigma-coded radio messages.
Historian: The u-boats in the North
Atlantic we’re in constant coded communication with Germany, saying where
these convoys were and arranging for groups of u-boats to come together to
attack them, and all of those messages were encoded using Enigma machines. So
cracking Enigma was the key to finding the u-boats and protecting the convoys.
Narrator: Turing begins by exploiting the mathematical and human weaknesses of
Enigma. Because the machine cannot encrypt the letter as itself, Turing eliminates
thousands of letter permutations. Combine this inherent flaw with the fact that
lazy, tired operators sometimes forget to change their personal settings each
day, and this lowers the odds further. But it’s the daily weather forecast that gives the
British their first major breakthrough. Every day, the Atlantic weather is broadcast
from the u-boats, and every day it follows the same format: wind speed, atmospheric pressure,
and temperature. Seeing the same message format each day gives Turing the idea of
using what he calls cribs — educated guesses as to what at least part of the message
might say. This is a crib in German of a weather
forecast from the Bay of Biscay region. The received encrypted messag is placed
against the German plain text. If any letters match up with themselves — s’s with s’s, v’s with v’s, then the crib is wrong. as Enigma cannot encrypt any letter as
itself. So they slide the message along until they find no matches. The British now have clues as to what
might be in the messages, but it’s still too many man hours to work through all
the permutations and decipher the many thousands of daily intercepts. So they develop a machine of their own
to rival the Enigma, a device that attempts to reverse the encryption process of an
Enigma machine known as the Bombe. It operates like a search engine, number-
crunching possible solutions to fragments of encrypted text. But can the Bletchley Bombe crack the Enigma code before the
German Navy wins the war of the Atlantic? British codebreakers of Bletchley Park
now have a weapon to defeat the Nazi Enigma machine: the Bombe. It’s not designed to break coded messages, but
to crunch to the millions of letter permutations contained in the so-called
cribs, the clues obtained by the repeated use of weather reports, greetings and
test signals sent by the Nazis. The operator sets each drum into position
according to the enciphered crib text they’re testing. As the machine operates
it generates intermittent electrical circuits that run through every possible
Enigma setting. The goal is to find an open circuit,
which means the Bombe has found a setting that converts all of the cipher
characters into plain text without any errors. It’s a hugely complicated device with
nearly 12 miles of wiring and 97,000 carefully machined parts. This Bombe has been reconstructed from plans and
drawings over the past 16 years. Back in 1943, Jean
Valentine was one of the Bombe operators at Bletchley Park, working under the
strictest security.
Valentine: Here in Bletchley, we had five Bombes and there were two people to each Bombe, so
there were 10 of us on a watch, and apart from them, you did not talk to anybody about your job. The minute you walked out of the Bombe room, got in a vehicle to go back to wherever you lived, you didn’t talk about it. Bletchley Park is one of the best examples
of complete security in history. The Nazis had no idea the British were
decoding their messages. They also had no idea that their codebooks and Enigma machines are being
retrieved from captured U-boats. Turing and his team are working around the clock,
cracking Enigma messages from u-boat positions, to the location of
reinforcements, and feeding this information to the Allies. By 1945 there are over 300 Bombes in
operation on both sides of the Atlantic. The days of the .Nazi Enigma are numbered The cracking of Enigma, and the intercepting and
decoding of Nazi messages shapes the outcome of many campaigns and battles of
World War II including D-day, Alamein, and Anzio. But it’s perhaps the vital role of
decoding the u-boat messages in the North Atlantic that saves the most lives.
Prime Minister Winston Churchill famously states that the Bletchley Park
codebreakers were the geese that laid the golden eggs and never cackled. Man: The war wasn’t won by the code-breakers; the war was won by boots on the
ground. Without it the war would not have been lost. But on the other hand with it
it was certainly shortened by a significant amount.

Cracking the NAZI Enigma Code Machine
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