Cracking the Uncrackable: How Did Alan Turing and His Team Crack The Enigma Code?

‘If everybody is thinking alike, then somebody is not thinking.’

George S Patton, a former senior officer of the US Army, hit the bull’s-eye with his legendary quote about intelligence. The reality is that there are times when nothing works according to plan. Your actions beget catastrophe, you miraculously manage to thoroughly bungle every opportunity that comes your way, and all your plans seem to go south. At times when you are completely at the end of your wits, a tiny clue often appears, something so conspicuous that it can easily escape the attention of everyone. The key to success is identifying the clue that “changes everything” and use it to your advantage.

Bletchley Park, London (Image Credit: standardissuemagazine.com)

This is precisely what happened during World War II in a place called Bletchley Park in Great Britain, where a team of scientists, mathematicians and cryptographers were attempting to break the Enigma Code.

What is the Enigma Code?

The Enigma Code is a cipher generated by something called the Enigma Machine. The Enigma Machine played a crucial part in communication among the Nazi forces during World War II. It was used to encrypt highly classified messages, which were then transmitted over thousands of miles to the Nazi forces at the front using Morse code.

How Did the Enigma Machine Work?

Credit: Everett Historical/Shutterstock

In order to understand how to crack the Enigma Code, one must comprehensively understand how the Enigma machine worked. You can read about its important components and function by clicking here.

What’s So Special About the Enigma Code?

What made the Enigma code, or any code, for that matter, so special?

The quality of any code is measured in terms of the number of possibilities one has to go through to arrive at the correct answer (this is one quantifiable entity, which is why we’ll only consider this).

In the case of the Enigma Machine, you have to get a number of settings of the machine absolutely perfect, or else the code cannot be cracked. What made the Enigma Code seemingly ‘uncrackable’ was the fact that you would have to go through more than almost 15 million million million possibilities to arrive at the correctly deciphered code!

How Did Turing’s Team Crack the Enigma Code?

Now, for the question that we posed in the title of this article… How did they actually crack the Enigma Code, which was considered one of the most ironclad, impossible-to-crack codes in history?

Alan Turing

A team of scientists, mathematicians and cryptographers are credited with cracking the Enigma code. Alan Turing was the head of this historic team. He, along with his colleague Gordon Welchman, made his own version of the Bombe Machine (the Bombe Machine was originally invented by the Poles, but it was unable to effectively decipher the codes as quickly as was required). The machine was better than the Polish version of the Bombe machine, but it also required a very, very long time to decipher any code, which was bad news for Britain and the other Allied nations. Turing had to come up with an idea that could allow the Bombe Machine to crack the code much faster than that.

The Bombe machine (Image Source: http://www.cryptomuseum.com)

One memorable day, Turing had an epiphany. He identified a weak spot in the Nazi encrypted messages – a chink in that ironclad armor! This flaw was something that could finally help to decipher every single encrypted Enigma message!

What Was the Flaw in the Enigma Code?

Let’s try to understand this important flaw with an example.

Suppose you wanted to encrypt a message that contained a total of 3 words. The first word of the message was, let’s say, ‘SCIENCE’. Now, the first letter that you would want to encrypt is ‘S’, so when you press the ‘S’ key on the keyboard of the Enigma Machine, an electric signal was generated that traveled through a lot of wires and rotors and ultimately lit up a different letter (say, ‘M’). So the ‘S’ in ‘SCIENCE’ would be encrypted as ‘M’.

Similarly, the other words would be encrypted as different letters than they actually were. On one end of the Enigma Machine, you typed ‘SCIENCE IS AWESOME’, but the encrypted output might have looked something like ‘MKSQER PO QAPEKRQ’, or something entirely different.

Did you notice anything about the above encryption?

Every letter was encrypted as a letter that was different than itself. Never once did it happen that a letter was encrypted as itself.

Quite simply, when you type ‘S’, it could be encrypted as any one letter of A,B,C….X,Y,Z. Any letter out of the 26 letters could be the, but not S. Therefore, an ‘S’ would never be encrypted as an ‘S’. Now, read the encryption of ‘SCIENCE IS AWESOME’ again and see if that holds true.

This was the single flaw in the Enigma code.

How Did this Flaw Help Crack the Enigma Code?

Now that you know that a letter can be encrypted as any letter other than itself, the total number of possible settings decreased exponentially.

To aid this process, all Turing needed was a word (or a group of words) that he was positive the Germans would use in each of their Enigma-encrypted messages. What was that word, or rather, that phrase?

‘Heil Hitler’

Germans put the phrase ‘Heil Hitler’ at the end of every encrypted message. This seemingly small mistake eventually contributed to their ultimate defeat.

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This is one of the many examples that proves that mathematics is not just a meaningless collection of numbers (which is what math-haters believe!). It’s something far greater… something that can save countless human lives.

This historical event proves another vital thing; perseverance and belief in your ideas eventually leads to success, no matter how insurmountable the problem may initially appear.