Enigma Machines, Alan Turing, The Imitation Game

Back in February 2013, I was assigned to work as contractor for an IC design project in European Semiconductor Company. IC which we planned to prototype is related with security protocols. Project Architect planned to give us introduction on the technical aspects of the project on a particular day. Architect was a security expert, worked on many security projects for many long years in European market. He was of Dutch origin. Particular day arrived and he started the presentation initially by throwing few questions among us. “How many of you have idea on cryptography?” “Do you have any idea on Engima Machines”? Though I know something on cryptography, I was very curious to know the enigma machines’. I researched for few months on same topic, but put back forth my plans to write on it. Today after nearly two years, my inspiration got rejuvenated again to write back on the same topic, after watching the film “The Imitation Game”.

The Imitation Game is a biographical film portraying, legendary British mathematician, computer scientist, war time code breaker “Alan Turing”. He is widely seen as the father of computer science and artificial intelligence. Film depicts life of Alan Turing, explores how his genius mind played a pivotal role in cracking enigma cipher codes, bringing the victory for allied forces in WW2 and shortening the course of WW2.Film also touches the controversial topic of homosexuality as Alan himself was a homosexual. Despite his achievements, he was prosecuted for homosexuality which was illegal crime then.

What are Enigma Machines? How they were important for Germans?

During World War 2 Nazi Hitler introduced a new kind of warfare known as Blitzkrieg. Blitzkrieg means lighting speed. Enemy defense lines were attacked through lighting speed of massive military forces mainly armored tanks along close infantry and air support. Based upon his four year stint as commander during WW1, Hitler believed tactical victories in war field can be achieved in quick time with blitzkrieg, avoiding any battlefield status quo situation. Speed of attack needs speedy communication among troops operating in battlefield. World war 2 was also known as wireless war as everyday sky was flooded with hundreds of radio messages. Nazi government trained thousands of wireless operators during preparation of WWII; Main motto behind their training was to interpret Morse code under any bad conditions. Sending any unencrypted secret messages in open sky is a risky choice; So Germans built an invincible cipher machine known as Engima machine. Enigma machine turns every input message into unintelligent gibberish, letter by letter. When the enemy intercepts this secret message, enemy will see only meaningless string of letters. In this way vital German war plans during initial years of WW2 remained complete secret.

Engima machine was initially built in 1920’s by Germans for commercial purposes. The German Navy began to use it in 1926, but it was the German Army who in 1928 created a version distinctly different from the commercial machine. They added a few modifications which vastly increased the encipherment permutations. Engima machine looks like an ordinary typewriter. But instead of printing letters in a paper, enigma machine outputs with an illuminated encrypted letter. Inside the enigma machine, system is built with few rotors. Pressing a key caused an electric current to run through a complex system of wires and gears, resulting in a ciphered letter illuminating. For instance, you might press the key for the letter "A" in the Keyboard and see "X" light up in lightboard.

Major components associated with Enigma machine are indicated in the above diagram

•  Keyboard
•  Plugboard
•  Rotors
• Lampboard

When the first rotor has turned through all 26 positions, the second rotor clicks round, and when that’s made it round all the way, the third does the same, leading to more than 17,000 different combinations before the encryption process repeats itself. Adding to the scrambling was a plugboard, sitting between the main rotors and the input and output, which swapped pairs of letters. In the earliest machines, up to six pairs could be swapped in that way; later models pushed it to 10, and added a fourth rotor.

Below videos will give better undertstanding of relation beteween encryption process and rotors

https://www.youtube.com/watch?v=mcX7iO_XCFA

     Complexity of the enigma machine is enormous. A standard three rotor Enigma with plug board could be set up 158,962555,217826,360000 different ways, that’s almost 159 million million million. If a normal human being start decoding the letter, it will take 20 Million years to complete it? Even with this colossal complexity, all the operators needed was information about the starting position, and order, of the three rotors, plus the positions of the plugs in the board. From there, decoding is as simple as typing the cyphertext back into the machine.

      With blitzkrieg and cipher machines, Hitler’s Nazi regime brought European countries to kneel in the early stage of the WW2.  Britain and other allied countries were clueless in cracking the Enigma machines.

  How Enigma machine was cracked?

     As the military strength of the Germany increased progressively after 1920’s, Poland which is at doorstep of Germany believed they are highly vulnerable. To gather intentions of potential enemy, Polish started intelligence gathering. Polish intelligence started intercepting the German radio transmissions which was using new cipher system (Enigma machine) and they didn’t find any considerable success in breaking it initially. In 1932 Polish Intelligence assembled a team of young mathematicians. It included Jerzy Rozycki, Henryk Zygalski and Marian Rejewski. With support of few stolen German documents and Engima daily keys, Polish team was able to crack the code. Rejewski built a first code breaking machine, which was later modeled exclusively as bombe by Alan Turing. Though Polish Team made good progress  in breaking the enigma, Germans added further 2 rotors in their Enigma machine, which made decrypting the message an impossible task. In 1939 When Germany invaded Poland, Polish intelligence has no options, as they met the British and French intelligence in outskirts of the Warsaw to handover the technology of code breaking to them.

Marian Rejewski

      

     Predicting the role of Enigma cipher messages in any future wars, British intelligence setup a secret workplace, 50 miles north of London known as Bletchley Park. Mathematicians, Chess champions were recruited to work in this secret place, to only crack the enigma codes. When UK announced the war on Germany in 1939, Alan Turing a young bright mathematician was summoned to work in Bletchley Park.  As Alan Turing always believed the concept that “A Machine can only break another Machine “, he made further modifications to the Polish code breaking machine,inventing a more powerful code breaking machine known as “Bombe”. German naval messages were still more secure that time, but with Alan Turing complex analytical bombe machines, the deciphering of the secret naval messages was made possible. Turing designed a machine that greatly reduced the tedious work of decoding. This development of breaking the enigma secret massages changed the course of war towards the Allied forces. Though Bletchley park team played a big role in the war, few brave soldiers who stole the secret enigma code documents from sinking submarines also needed to be mentioned here. As the Germans became more suspicious, security-conscious of the enigma machines, they changed the number of rotors and formats. At this stage U.S too entered this crypto analysis building bigger and faster machines for breaking the code. A number of faster versions were produced and were in almost constant use in the final months of the war.

Alan Turing

    Alan Turing Legacy 

• Turing broke the German Navy, Airforce and Army Enigma codes and handed the allies an advantage in the Second World War Historians estimate that breaking Enigma shortened the war by more than two years, saving over 14 million lives. It remained a government-held secret for more than 50 years

• Turing's work inspired generations of research into what scientists called "Turing machines", now known as computers. With his invention of Bombe, which was later modelled as the World’s first computer with enhanced capabilities. Turing also proposed the concept of “Turing Machines” a machine which could perform any algorithmic functions. For these contributions, He was called as “Father of Modern computers and Artifical Intelligence”

      Some of his legacy associated with fields like Speech encryption, Morphogenesis, Chemistry and physics and Chess computer models were explained in below article.

              http://www.wired.com/2012/06/alan-turing-legacy/

     Conclusion:

     Just like great scientist(Nikola Tesla), Alan turing death was sad one. He was casualty of the end of hostilities. In 1952 he was arrested for homosexuality and lost his security clearance. He was convicted of what was then criminal activity and chose to undergo a program of oestrogen treatment rather than go to prison. In 1954, he committed suicide by taking cyanide. He died at very less age of 41. Between 1885 and 1967, approximately 49,000 homosexual men in the UK were convicted and imprisoned of gross indecency under British law. In 2013, Queen Elizabeth II granted a posthumous royal pardon, honoring Alan Turing for his achievements during the war.

      The movie “Imitation game” was based on book “Alan Turing: The Enigma”. Few inaccuracies from book to film related to character and story are listed below

•     Alan Turing had more sense of humor, the movie makes him look like that he is on the other side of the spectrum.
• ·     He did know German, in fact he have traveled before and after the War to Germany.
• ·     He did not call the first machine "Christopher", that is just too much right in the film
• ·     Hugh Alexander was not competing with Alan, he joined the team after a while when he was already working on creating the machine.
• ·    The majestic Joan Clarke was not recruited by Alan through a word puzzle. She was recruited by one of her academic advisors. In the movie it makes it a bit awkward to show their relation. But they actually did love each other according to conversations they had.

         Java Source code for Engima cryptography is available in below link

             https://code.google.com/p/startpad/source/browse/labs/js/enigma/enigma.js

      Sources: Wikipedia, Quora, Other science and history websites