Heroes of the Internet Part Two: Alan Turing.

Heroes of the Internet Part Two: Alan Turing.

In the first half of the twentieth century, back when doctors still precribed cigarettes, is really when the fundamental ideas of modern day computing first began to emerge. It was during this time that a computer model was described that wasn’t limited to specific mathematical tasks, it could also simulate the operation of any computer or algorithm, becoming a universal model of computation that laid the theoretical foundation for modern computers. The person that invented this model was, of course, Alan Turing.

Alan Turing: The Really Sad Part.

I’m going to start at the end of this story for a reason. Remember this part when you read the rest of this story.

If I write this story in chronological order, the end becomes an eplically sad footnote to what’s arguably one of the greatest acheivements by a single person. Not only did the acheivements of Alan Turing pave the way to you having that smartphone in your hand and being able to post on social media at whim, but they also saved thousands of lives.

The sad part?

Homosexuality was decriminalised in England and Wales in 1967 with the passage of the Sexual Offenses Act of 1967. Alan Turing (23 June 1912 – 7 June 1954) was gay.

Alan Turing was persecuted for his homosexuality, which (as you can probably imagine) had a significant impact on his life.

Turing was convicted of “gross indecency” in 1952 due to his homosexual relationship, as homosexuality was illegal in the United Kingdom at the time. As a result of his conviction, he was subjected to chemical castration through hormone treatments as an alternative to imprisonment (yep, that was what we did back then). This treatment had severe physical and emotional effects on him.

Tragically, Alan Turing died on June 7, 1954, at the age of 41, from cyanide poisoning. His death was officially ruled as suicide, although there has been debate and speculation about the exact circumstances. His death had a profound impact on the world of science and computing.

While you read the rest of this story, bear this in mind: That you can be one of the greatest inventors of your time, that you can gift the world with ideas that would develop in to humanity changing technologies, that you can do work that saves thousands of lives and aguably helps to win a world war, yet you can still be persecuted to death by an establishment that felt they had the right to dictate who people should love.

Heroes of the Internet Part Two: Alan Turing

Alan Turing and the Turing Machine.

Alan Turing was an English mathematician, computer scientist, logician, cryptanalyst, philosopher and theoretical biologist. He graduated at King’s College, Cambridge, with a degree in mathematics. In 1938, he obtained his PhD from the Department of Mathematics at Princeton University. I daresay his CV took some reading (and probably a lot of supplemental reading).

Turing was highly influential in the development of theoretical computer science. He is widely considered to be the father of theoretical computer science and artificial intelligence.

Alan Turing provided a formalisation of the concepts of algorithm and computation with his Turing machine, which was really the first “idea” of a general-purpose computer (what we consider as computers today). While the Turing machine wasn’t a physical machine, it laid the theoretical foundation for the concept of a computer.

Yep, Alan Turing came up with a theory that would become the prologue to the computers that we have today.

The Turing machine is essentially a simple imaginary computer. This consists of a tape with symbols, a read/write head, a finite set of states, and a set of transition rules.

  • Tape: Used to record data and to store written data.
  • Symbols: The data stored on the tape.
  • A read/write head: What reads data from and writes data to the tape.
  • A finite set of states: The limited number of internal conditions or situations it can be in. These might be “start,” “read,” “write,” “halt,”. These states help control the machine’s behavior.
  • Set of Transition Rules: These rules dictate what the machine should do when it is in a particular state and reads a certain symbol on the tape. The rules determine how the machine switches between states, reads or writes symbols on the tape, and moves the tape’s read/write head. They define the machine’s step-by-step instructions for performing tasks.

It can simulate the operation of any algorithm, making it a universal model of computation. In essence, the Turing machine is a theoretical device that can perform the tasks and calculations that a modern computer can, given enough time and tape.

Although the Turing Machine would have been a lot slower, in principle, it’s no different from the computers that we have today, as they all work in this manner. It would be a bit of a stretch to say that Alan Turing invented computers, or even that he invented the first computer, because at the time, this was just a theory.

That aside, Turing was still very “ahead of his time”. I mean, an idea of something has come about and then be developed before that thing can be invented. That’s what Alan Turing came up with; the first idea of a computer.

At this point you might ask “Didn’t Charles Babbage come up with that idea first?”

Whilst Charles Babbage’s Difference Engine was really the first idea for a “thinking machine” his was limited to mathematical functions, where as the Turing Machine can simulate the operation of any computer or algorithm. A Turing machine can be programmed to perform a wide range of tasks and operations, not just mathematical computations.

War! Huh! What is it Good for?

Putting theory in to practice, apparently. I’ll come to that later.

World War II started on September 1, 1939, when Germany lead by Adolf Hitler invaded Poland. This prompted Britain and France to declare war on Germany on September 3, 1939, marking the official beginning of World War II.

At this time we had radar, spy planes (with propellors), radio communications (which could be intercepted) and cryptography. World War II had a much higher level of military intelligence than any previous war. A lot more communciation to a greater number of troops over a much larger area would give either side an advantage, but that could all be undermined if communications could be intercepted by an enemy to find out what their opponent was doing.

Although the interception of communications couldn’t be completely eliminated, they could be encrypted.

Encryption is a method that we still use today (see the padlock in the browser’s address bar, that’s showing that you’re using encryption when visitig this website) to make intercepted communications useless to anyone other than the intended parties. These intended parties had “keys”. On the transmistting end a “key” would be used to encrypt data, and on the receiving the “key” would be used to unencrypt the data. Anyone intercepting the encrypted communication would see it in it’s encrypted form, which was pretty much useless (as it would look like gibberish), unless you had the key to decrypt the data.

If you’re at war and your enemy is using ecnryption, being able to intercept your enemy’s communications isn’t of any value unless you can decrypt the communications.

The Enigma Machine.

Although it does sound like something from a 1960’s Adam West Batman episode, the Enigma Machine did exist.

The Enigma Machine was what Germany used to encrypt it’s communcations. This was a powerful tool in Germany’s machine of war, as it meant that it didn’t matter if their communications were intercepted because what was intercepted was useless unless it could be decrypted.

The Enigma Machines (yes there were more than one) provided the “keys” to encrypt and decrypt data. The transmitter would use an Enigma Machine to encrypt the communication, and the receiver would use another Enigma Maching to decrypt the communication. Any party intercepting the communication would only obtain encrypted data, which they couldn’t do anything with, as they didn’t have the key that the Enigma Machine provided.

Enigma Machine

The Enigma Machine worked through a complex and changing set of encryption settings, making it challenging for Allied codebreakers to decipher the messages. Here’s how it worked:

  • Rotors: The core of the Enigma machine was a set of rotors. These were wheels with electrical contacts on both sides. Each rotor had 26 contact points corresponding to the letters of the alphabet.
  • Plugboard: In addition to the rotors, the Enigma machine had a plugboard. This was an external panel where operators could plug and unplug cables to create connections between pairs of letters. The plugboard further scrambled the input and output of the machine.
  • Typewriter-Like Keyboard: The operator would type the plaintext message letter by letter on a keyboard.
  • Electric Current Path: When a key was pressed, an electric current passed through the machine, engaging the plugboard and the rotor system. The current would travel through a series of contacts, passing through the plugboard, the rotors, and then back through the plugboard.
  • Rotor Movement: With each keypress, the rightmost rotor would advance by one position. Once it completed a full rotation, the next rotor to the left would move one position. The position of the rotors determined the substitution of letters, making the encryption dynamic.
  • Output: The electric current would then illuminate a letter on a display, indicating the encrypted letter for that input. The letter was sent as part of the encoded message.

The key to decoding Enigma Machine encrypted messages was knowing the initial rotor settings (“key”) and the plugboard connections. The Germans changed these settings daily, making it extremely difficult for Allied codebreakers to decipher messages.

Even if the Allies managed to obtain the rotor settings and plugboard connections, this information would only be valid for one day, and the communications made in that day. Not only were the Germans encrypting data, but they were also changing their encryption “key” on a daily basis. This effectively meant that any unencryption effort would have been a daily task for the Allies.

Breaking the Encryption

Bletchley Park.

The codebreaking, or decrypting, effort at Bletchley Park started as early as the 1930s.

In the years leading up to World War II, there was growing concern about the rise of Nazi Germany and the potential for conflict. British authorities recognised the need to prepare for any future conflict, and this included planning for the interception and decryption of enemy communications.

Britain had a tradition of expertise in cryptanalysis dating back to World War I and even earlier. During World War I, the British had successfully intercepted and decoded German communications. This experience and knowledge laid the groundwork for the codebreaking efforts during Wold War II.

The Enigma Machine had been invented before the beginning of World War II, and the effort to decrypt the Enigma Machine had also started before Wordl War II had begun.

British codebreakers were struggling to decrypt the Enigma machine’s messages. While they had some successes and made progress, breaking the Enigma code was an extremely challenging and complex task. The codebreakers were working on the problem but had not achieved consistent and complete success.

In early 1939 (still before the outbreak of World War II) Alan Turing joined the Government Code and Cypher School (GC&CS) at Bletchley Park. Not only was Turing a mathematical genius, but he had also studied the workings of the Enigma while it was still in use in Germany, making him one of the few people who could contribute significantly to breaking the German code.

The Capture of an Enigma Machine and Code Books.

One of the most critical breakthroughs was the capture of Enigma machines and associated codebooks by the Allies. The British, in particular, obtained an Enigma machine from a German submarine in 1941.

This event provided crucial insights into the specific machine settings and wiring used by the Germans, which significantly aided the codebreaking efforts at Bletchley Park.

The capture of the Enigma machine occurred in the spring of 1941 when the British Royal Navy intercepted a German U-boat (submarine) known as U-110. The U-boat was forced to the surface after being damaged during an attack by British warships and aircraft.

As the crew abandoned the sinking submarine, they left behind sensitive equipment, including an Enigma machine and codebooks.

The British authorities took great care to keep the capture of the Enigma machine and codebooks a closely guarded secret. They didn’t want the Germans to know that their codes had been compromised.

The Bombe (1940).

The Bombe was an electromechanical device made and used by British codebreakers at Bletchley Park during World War II to decrypt German Enigma-encrypted messages.

The primary credit for the Bombe’s design goes to Alan Turing, Gordon Welchman, and others involved in the project. Alan Turing’s contributions were particularly significant, as he played a key role in the development of the machine’s design and operation.

The Bombe was developed to automate the process of checking possible rotor settings for the Enigma machine, and it played a crucial role in the decryption of German Enigma Machine encrypted messages, particularly those used by the German military during World War II.

This is how the Bombe worked:

  • Rotor Settings: The Enigma machine used a set of rotors to scramble the letters in a message. To decrypt a message, the key challenge was to determine the rotor settings used by the Germans for a particular message. The Bombe’s primary function was to discover these rotor settings.
  • Known Plaintext: To operate the Bombe effectively, codebreakers needed to have some “known plaintext” from the message they wanted to decrypt. Known plaintext was a part of the message that was known to the codebreakers, such as a weather report or specific phrases commonly found in German military communications.
  • Multiple Simulations: The Bombe consisted of multiple sets of rotors (simulating the Enigma’s rotors) and a system of electrical connections to replicate the Enigma machine. Each set of simulated rotors corresponded to a possible rotor setting in the Enigma.
  • Testing Possible Settings: The Bombe would simultaneously test a large number of possible rotor settings, using the known plaintext as a starting point. It would go through the simulated rotor permutations and check the output against the known plaintext.
  • Checking for Plausibility: As the Bombe cycled through the rotor settings, it looked for “cribs” or portions of the message that matched the known plaintext. If it found a plausible match between the simulated output and the known plaintext, it indicated a potential correct rotor setting.
  • Verification: A successful setting was not taken as conclusive evidence on its own. Instead, the machine generated a “menu” of possible rotor settings. The codebreakers then conducted a more thorough examination to confirm the correct rotor settings.
  • Iterative Process: The codebreakers would run the Bombe repeatedly, often cycling through different sections of the message to find additional rotor settings. The process was highly iterative, and multiple runs were required to recover the complete message.
  • Expedited Decryption: The Bombe significantly expedited the decryption process by automating the trial-and-error testing of possible rotor settings. Without the Bombe, this process would have been much more time-consuming and labor-intensive.
The British Typex (early 1940’s).

The British Typex cipher machine was developed during the early 1940s, specifically during World War II. Its design and production began in response to the need for a cipher machine that resembled the German Enigma machine, which was being used for the encryption of military communications.

The British Typex was created at Bletchley Park, the central site for British codebreakers and intelligence operations during the war. Its development and use were part of the broader British efforts to understand and simulate the Enigma machine, which was crucial for decrypting German military communications.

The British Typex was an important tool for training and experimentation in the context of understanding and breaking the Enigma code, and it contributed to the success of the British codebreakers in deciphering German messages.

Bletchley Park FTW!

With a combination of the intercepted messages, the captured Enigma Machine, a Typex to experiment with, a Bombe to work out rotor settings and a lot of brain power from Turing and the rest of the team at Beltchley park, the Enigma Encrypted messages could be decrypted.

Due to the changing and subsequent working out of rotor settings, intercepted messages couldn’t be worked out in real time, but they could ultimately be worked out. The Allies were now able to decrypt messages that the Germans were sending using the Enigma Machines.

All of this was kept top secret. If the Germans had known that the Allies were now able to effectively eavesdrop on their communications, they wouldn’t have carried on communicating in this way. Not only was there the need to keep the success of the Bletchley Park decryption effort secret, there was also the need to not act in a way that would suggest that the allies could now intercept and decrypt German communistions.

You might wonder what good all this did what with the need for secrecy to the degree where intelligence couldn’t be acted upon.

The Effect of Being Able to Decrypt.

The information gained from deciphering Enigma-encrypted messages, especially during World War II, was a critical factor in the Allied victory. It provided valuable intelligence that was used in various ways to shape military operations, make strategic decisions, and protect against enemy threats.

Some examples of these are:

Battle of the Atlantic.

The decryption of German naval Enigma messages played a vital role in the Battle of the Atlantic, where German U-boats posed a significant threat to Allied shipping. By intercepting and decoding U-boat messages, the Allies could track U-boat movements, protect convoys, and target enemy submarines. The decryption effort was so successful that by 1943, the Allies were sinking U-boats faster than the Germans could build them. This contributed to a significant turning point in the Battle of the Atlantic.

D-Day Landings.

Decrypted intelligence from Enigma-encrypted messages was instrumental in planning the D-Day landings in Normandy in 1944. It provided information about German troop deployments, fortifications, and potential countermeasures. The Allies conducted deception operations to mislead the Germans, and the accuracy of their intelligence was a crucial factor in the success of the operation.

North African Campaign.

Enigma intelligence was used in the North African campaign, providing insights into the plans and movements of German and Italian forces. This intelligence allowed the Allies to outmanoeuver the Axis powers and achieve significant victories.

Air Campaigns.

Deciphered messages from the German Luftwaffe (air force) were used to anticipate enemy air raids and strategic objectives. This information helped in planning air raids and protecting key targets.

Scientific and Technological Insights.

The intelligence from Enigma-encrypted messages sometimes provided insights into German scientific and technological developments, including weapons and radar systems. This helped the Allies adapt and develop countermeasures.

Statistical Significance.

At the height of its success, Bletchley Park was decrypting up to 84,000 intercepted messages per month. It’s estimated that the codebreaking efforts shortened the war in Europe by two years, saving countless lives.

Strategic Decisions.

Information from Enigma decrypts influenced broader strategic decisions, including the allocation of resources and the prioritisation of military campaigns.

The impact of Enigma intelligence extended beyond specific battles and campaigns, as it allowed the Allies to anticipate and counter German actions throughout the war. It significantly contributed to the overall success of the Allied forces during World War II. The use of this intelligence is often cited as one of the most successful and impactful aspects of the wartime codebreaking efforts.

Although it’s very hard to say for sure, some estimates suggest that the decryption of Enigma Machine messgaes is likely to have saved hundreds of thousands of lives.

It Wasn’t all Alan Turing.

The decryption of Enigma machine messages, particularly the military Enigma used by the Germans during World War II, benefited significantly from the contributions of many individuals and teams. While Alan Turing made invaluable contributions, it was a collective effort that involved many skilled codebreakers, mathematicians, engineers, and cryptanalysts. It would be inaccurate to attribute the decryption solely to Alan Turing.

That said, Alan Turing’s work was of extraordinary importance to the codebreaking efforts at Bletchley Park, and he played a critical role in developing innovative methods and machines that significantly contributed to the decryption of Enigma-encrypted messages.

The design of the Bombe, his understanding of mathematics, logic, statistical analysis, his cribs and codebreaking techniques were all absolutely invaluable to to acheivements of the Enigma codebreaking effort at Bletchley Park.

Alan Turing’s Other Acheivements.

Although the work, and it’s effect, that was carried out at Blethchley park had an enormous positive humanitrian impact, this (and the Turing Machine) weren’t the only things that Alan Turing achieved in his lifetime. Whilst these two things are what he’s renowned for, other examples of his acheivements are:

Computability and Complexity Theory.

Turing’s groundbreaking paper, “On Computable Numbers,” introduced the concept of computability and the Church-Turing thesis, which established that any effectively calculable function can be computed by a Turing machine. This work played a fundamental role in the theory of computation.


Turing made contributions to various areas of mathematics, including mathematical logic, algebra, and number theory.


In his later years, Turing explored mathematical biology, particularly morphogenesis, the process by which patterns and structures form in biological organisms. His work in this field contributed to the understanding of biological growth and development.

Computing Machinery and Intelligence / Artificial Intelligence.

Turing is considered one of the pioneers of artificial intelligence (AI).

Turing’s 1950 paper, “Computing Machinery and Intelligence,” discussed the possibility of machine intelligence and the idea of artificial intelligence. He proposed the Turing Test as a way to measure of a machine’s ability to exhibit intelligent behaviour indistinguishable from that of a human.

His ideas continue to influence AI research.

The Turing Award.

The Association for Computing Machinery (ACM) established the Turing Award in 1966, considered one of the highest honors in computer science. It is awarded to individuals who have made significant contributions to the field.

In the End.

As I’ve already told you, the end to Alan Turing’s story isn’t a happy one. I won’t repeat myself given how sad it is.

Needless to say, even though his later years, and ultimately his death were shrouded in sadness, he did leave a legacy on this planet.

He’d theoritically invented the first computer, he’d made a machine (not technically a computer) designed to decrypt messages, he’d put his mathematical theory and logic in to pratice, perhaps saving hundreds of thousands of lives in the process.

There’s not a lot of people that can say that.

There’s also not a lot of people that can have the first idea of something that never existed before.

Almost all of us use computers everyday to do things. We even use computers without realising we’re using them. Those tasks being “computed” rather than manually carried out, or operated in clockwork were what Alan Turing gave us.

And it’s for that reason that Alan Turing gets in to the Heroes of The Internet.

Alan Turing 23 June 1912 – 7 June 1954

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