Cold Open
The following presentation is not suitable for young children, listener discretion is advised…
SFX: ship engine.
Captain Lachlan MacKinnon, 58, pulled his greatcoat tight to keep out the cold October night, then peered through his binoculars and scanned the North Atlantic Ocean.
To call him a captain was almost amusing. He retired from the Royal Navy one year earlier at the rank of Vice Admiral, in 1939. But when Nazi Germany declared war on his homeland Great Britain a few months later, Captain MacKinnon volunteered for the Royal Navy Reserve. He was put in command of merchant convoys, which brought the UK the vital resources needed to avoid starvation and capitulation—food, iron ore, chemicals, vehicles, and more.
But actually making the trip was easier said than done.
This convoy, his 11th, was codenamed SC 07. It originated from Nova Scotia, Canada, and consisted of 35 merchant ships, many old and slow. Captain MacKinnon’s ship, the Assyrian, was a cargo freighter carrying grain. For most of the trip, they’d only had one military escort.
By now, about ¾ of the way through the journey, SC 07 was already a few vessels short. That was thanks to the U-Boats, which were the submarines used by the Nazis that prowled the Atlantic.
Having fought in World War I, the captain was no stranger to Germany’s submarine fleet. But these days, there seemed to be more of them than ever. Worse, the U-Boats seemed to always know where they were. Meanwhile, the British were constantly in the dark as to the whereabouts of the Nazi subs.
The captain tried to put these thoughts out of his mind and focus on the horizon.
And then, he saw it. A periscope. The tell-tale sign of a U-Boat. Just 100 yards ahead.
The military escorts were too far away to be of assistance. And MacKinnon had no command over them anyway. He had one choice.
Battle stations. Full steam ahead.
They were going to ram the U-Boat.
The Assyrian shuddered as it increased speed to 10 knots. The U-Boat quickly turned around and fled.
Don’t lose her!
There was no way the Assyrian could catch the U-Boat, but MacKinnon had no other options. The Assyrian’s main gun was mounted on the stern, rendering it useless. They had to hope the U-Boat would slow down enough to overtake it—a slim hope indeed.
After 40 minutes, the U-Boat was slipping away. Worse, the Assyrian was now separated from the convoy
And then, the submarine slipped beneath the waves. MacKinnon felt a knot in his stomach. They were sitting ducks.
SFX: three torpedoes launch
Torpedoes in the water!
MacKinnon looked through his binoculars. Three, headed right for them.
Evasive maneuvers!
The Assyrian dodged the first two torpedoes, but the third struck the starboard side.
SFX: torpedo hitting ship.
It destroyed the ship’s lifeboats.
Abandon ship!
Sailors fled the sinking Assyrian. The ship broke apart, separating MacKinnon and a few others from the rest, and forcing them to improvise a life raft out of whatever they could find. MacKinnon and his comrades heaved their raft to the water. It immediately broke apart. With no other choice, they jumped into the freezing water and grabbed whatever floating wreckage they could find.
As MacKinnon watched his ship go under, he could only guess how many men he’d lost, or how the other ships in the convoy were faring.
He tried to remain conscious. Hours went by. Finally, another convoy ship appeared on the horizon. MacKinnon was too weak to call out, or even to accept a rope to pull himself aboard. He felt himself being pulled into a net and hauled out of the water as he passed out.
He woke in a Liverpool hospital. He’d barely survived pneumonia, but all he cared about was the fate of the convoy.
When he finally learned the truth, it was worse than he could have imagined.
20 ships sunk, 141 dead, nearly 80,000 tons of resources lost.
The captain would never quite recover.
News of the convoy massacre devastated the Royal Navy and the British Government, as well—but these stories were becoming all too common.
The British had to find a way to stop these U-Boats from ravaging their ships, or else lose the war.
Their biggest challenge? The Nazis were using a sophisticated encryption machine that made their communications incomprehensible to outsiders, allowing their U-boats to stay several steps ahead.
Britain’s best hope was an unlikely war hero, a young, gay, socially awkward mathematician named Alan Turing. Turing had to find a way to crack these seemingly unbreakable Nazi messages, and fast, or all would be lost.
On this episode: British mathematicians, Nazi code breaking, the birth of computer science, and the high-stakes game to win World War II. I’m Keith Korneluk and you’re listening to Modem Mischief
You're listening to Modem Mischief. In this series we explore the darkest reaches of the internet. We'll take you into the minds of the world's most notorious hackers and the lives affected by them. We'll also show you places you won't find on Google and what goes on down there. This is part one of our two-part series on Alan Turing.
Patreon Promo
Hello everybody and happy new year! I spent a lot of time over the holidays thinking about this show and all of you. It’s been a hell of a ride the last couple of years on Modem Mischief and that’s all thanks to your support. The reality is, this show is not cheap to produce which is why we could use your support. If you love the show, you can show us your support by becoming a patron on Patreon. For just $5 per month, you’ll receive an ad free version of Modem Mischief as well as bonus episodes exclusive to subscribers. Just go to patreon.com/modemmischief to sign up. If you listen on Apple Podcasts, you can become a member of “Modem Mischief Elite” and get the same stuff. If not, no worries. Regardless of the support, we appreciate all of you that listen. And, now...on with the show!
Act One
As you might have noticed, these episodes are going to take us way back in time, at least as far as technology is concerned. You might be wondering, why is Modem Mischief doing a story about someone who lived before modems existed?
The story of Alan Turing takes us back to the birth of computers, and computer hacking, Turing is one of the people who made computers possible, and he’s considered one of the first “hackers.” Without him, we couldn’t walk on the moon, or use our smartphones to look at furry porn.
Just me?
Aaaanyway, on with the show.
SFX: busy dining hall
Sorry, excuse me, sorry.
About four years earlier, in 1936, 24-year-old Alan Turing carried his lunch tray past crowded rows of undergrads until he reached the High Table. It was literally eight inches higher than any other table in the King’s College dining hall and reserved for university Cambridge Fellows, like Turing.
He didn’t spot any of his other colleagues from the mathematics department, and Cambridge etiquette of the 1930s dictated that you take the nearest available seat, so he plopped down next to a few folks from the classics department, plus the Vice Provost.
Ah, Turing, said the provost. I was just telling everyone about a new musical comedy I saw in London. “Careless Rapture,” by a Welshman named Novello.
I’m partial to Shaw myself.
Too political for my liking. So, how did you occupy the past weekend?
Turing thought over his response. He’d mostly worked on his PhD thesis, but it was frowned upon to talk about your work at the High Table. Turing was no stickler for convention, but he did respect rules that he found logical, and he understood the logic of academics discussing subjects other than their area of expertise—who knew where it might lead?
I’ve long held an interest in cryptography, or the process of encrypting messages in a way that no one can read them—unless you have the key, or you can break the key. Instead of creating order out of chaos, cryptography creates chaos out of order.
He looked over the Fellows’ faces. Some eyes were glazed over, but a few were paying close attention. This gave him the confidence to continue.
There are many ways to encode a message, but the simplest is substituting one letter for another—the kind any child can solve in a newspaper puzzle. The more complex the key, the more difficult the code is to crack—but it still can be cracked. What I’d like to do is devise a cipher that cannot.
And how would you achieve that?
Well, I’m working on a machine, one that can perform any mathematical equation imaginable.
And what do you call it?
Well…it doesn’t exist. It can’t exist, not in its current form. But that’s not the point. I came upon the idea in my recent studies into Hilbert’s Decision Problem, about which I am preparing a paper—
I see, the Vice Provost interrupted with a frown. Turing had made a faux pas by bringing up his work, and the conversation shifted.
But one of Turing’s fellow…Fellows, a professor named Adcock, was struck by Turing’s comments.
Turing didn’t know it, but Adcock was a consultant for Room 40, which was part of the British Government’s Code and Cypher School—its codebreaking apparatus. And Turing’s passion for cryptography made him an excellent candidate for recruitment—especially with war on the horizon.
That’s one theory for how Alan Turing caught the British government’s attention. We can’t know the truth, because so much of Turing’s wartime contributions are classified.
There are many ways the British government could have discovered Turing’s prodigious mathematical and cryptography skills. Bottom line, it needed him.
Turing was born in the right place at the right time to save his country, but the wrong place at the wrong time in nearly every other aspect of his life.
Turing was born in London in 1912, to a father who worked as an administrator in colonial India, and a mother who came from a family of railroad engineers. His parents mainly lived in India, opting to leave Turing and his older brother, John, in England with relatives. So, they saw little of their parents.
Turning loved science and performing his own experiments. His interests ranged from chemistry to biology to of course mathematics. He was usually more advanced than his schoolteachers.
It was also during his teenage years that Alan Turing first explored his sexuality. Turing was gay in a time when the UK criminalized homosexuality. Despite this, Turing found relative safety in the upper-class school system, where homosexuality was much more tolerated.
Even at an early age, Turing saw little sense in this law. A fan of Lewis Carroll’s Alice in Wonderland, Turing felt that he lived in a “Looking Glass world,” where the rules of reality were flipped upside down. To him, his sexuality was completely natural. So, he made little effort to hide who he was.
Turing became close friends with a classmate one year ahead named Christopher Morcom. Christopher shared Turing’s interest in mathematics and introduced him to astronomy. Turing fell in love. Christopher didn’t reciprocate but accepted his friend anyway—a pattern that would recur throughout Turing’s life.
But Christopher had a secret. The day their final term together began, Christopher never showed. Christopher passed away from bovine tuberculosis, contracted as a child.
Turing was devastated and never quite got over it. He would maintain a correspondence with Christopher’s mother for the rest of her life.
Turing first discovered an interest in cryptography during his high school years, and it continued into his university days. He earned a scholarship to King’s College, Cambridge. Here, he studied under some of the greatest mathematicians of his day, and finally found challenges that suited his intellect. His graduate dissertation earned him a Fellowship at just 22.
But while Turing was happily pursuing academics, the forces that would shape his life were in motion.
In 1933, Adolf Hitler was elected Chancellor of Germany, but Turing was mostly unconcerned about politics. In 1935, he began a graduate research project that would produce the first major achievement of his life—and one that would change humanity forever.
While attending a lecture, Turing encountered an abstract mathematical theory posed by the German mathematician David Hilbert.
Hilbert proposed that every valid mathematical formula must have a correct solution. So, there must be an algorithm that can determine whether any mathematical formula is true or false. It was called the “decision problem,” or the “Entscheidungsproblem” in German.
Turing set out to prove that no such algorithm exists. He imagined a machine that could be programmed to perform any kind of math equation. It would be fed with an infinite loop of tape, and it would have a pointer capable of writing or erasing symbols onto that tape. As the tape is fed through the machine’s electromagnetic switches, it performs its calculations. Once it arrives at a solution, it halts. So, if this machine were required to solve an unsolvable math problem, it would continue endlessly.
Turing called this a “computing machine,” but it would later come to be called a “universal Turing machine.” Today, we’d call it a computer.
But how does a hypothetical machine that’s impossible to build, and that was intended just to solve math problems, lead to today’s computers?
Turing wasn’t the first person to come up with the idea for a computing machine. In Turing’s time, he could access simple calculating machines that could add, subtract, multiply, or divide. There were hundreds of other machines created to do more sophisticated work, like engineering.
But Turing took it many, many steps further. His universal machine could be programmed to do the work of any calculating machine, creating an all-in-one device capable of computing any mathematical formula. Not only that, if given enough instructions, it could be programmed to do all sorts of human activities—like typing, photography, making telephone calls, and more. His machine could even re-program itself as it performed its calculations, to make itself more efficient.
It could think. It could learn. Turing thought of it as an “Electronic brain.” Obviously, Turing’s idea was decades ahead of its time. But it was much closer to reality than anyone had ever come before.
Turing came of age during a time of great political strife, but also great innovation. The early 20th century saw advances in physics, like Einstein’s theory of relativity or quantum mechanics. There were innovations like the light bulb, the phonograph, the radio, the television, the automobile, the airplane, and many more. In particular, advances in electronics made it possible to use switches, valves, and vacuum tubes to perform thousands of operations within a second.
This allowed machines to perform bigger and bigger calculations, which would make everything from nuclear weapons to space flight possible—and allow Turing to build, if not a literal universal machine, then something close to it.
But as theorist Lancelot Hogben observed, science doesn’t follow the inclinations of scientists; it bends to the will of politics and economics. It would be many years before Turing could pursue his dream of building an Electronic Brain.
In 1936, Turing published his ideas in a paper called Computable Numbers. That same year, Hitler ordered Germany’s first military operation since the Great War when he occupied the Rhineland. Europe was closer to war than it had been in a generation.
Today, Computable Numbers is considered the foundation of computer science, but at first it didn’t make a splash. In the meantime, Cambridge decided that Turing would be best suited to continue his research with another leading mathematician exploring Hilbert’s Decision Problem, Alonzo Church. This meant Turing would spend the next two years at Princeton’s Institute for Advanced Studies, where he would be colleagues with Church, Einstein, and the mathematician John von Neumann.
In September 1936, Turing made the six-day voyage across the Atlantic and landed in New York at Ellis Island, which was crowded with immigrants, including thousands of Jewish refugees fleeing Nazi Germany daily.
He didn’t care much for America, where he felt that most people alternated between being dull and self-absorbed. He also found that unlike at Cambridge, American scholars weren’t as collegial—and it didn’t help that Turing hated self-promotion.
Still, his time with Church was productive. Turing pursued further research into mathematical problems. He also continued his passion for cryptography. Always hoping to connect mathematical concepts with the real world, Turing began learning electrical engineering to invent his own machines. At Princeton, he invented a device he called a “binary multiplier,” which could scramble large numbers randomly.
It held obvious cryptology applications. So, it’s possible that when Turing returned to England in the spring of 1938, and English customs discovered this strange machine built by an equally strange individual, that this is how his skills came to his government’s attention. Again. We can’t know.
By then, Hitler had annexed Austria, and war was on the horizon. The UK needed codebreakers like Turing. We don’t know when or how it happened, but some time in 1938, the British government contacted Turing and invited him to London, where it gave him a cryptography test. He passed easily.
, Turing was brought to London’s Admiralty Building, headquarters of the Government Code and Cypher School. He was brought into the office of its director, Commander Alistair Deniston, a Scot.
An academic, Turing wasn’t used to the commander’s stiff military bearing. Should he salute? The commander motioned to a chair.
Dr. Turing, I’ll get right to the point. As you know, our nation is on the path to war with Germany and its allies. I believe that codebreaking will be central to winning this war. That’s what we do here–but we don’t do it correctly. For too long we’ve treated codebreaking as a linguistic problem, when in fact it’s a mathematical problem. That’s why we need you. Will you submit your name for government service?
Turing considered his options. He’d have to pause his mathematical career indefinitely. But his country needed him–a country that included his friends, his parents, and his brother. He saw no other choice.
Happily.
What Turing didn’t yet know was that the Nazis had a secret weapon, an encryption machine thought to be impossible to crack. It was called Enigma.
Act Two
SFX: bicycle
In the spring of 1941, Alan Turing pedaled his bicycle into work. The ride was pleasant, even if he was wearing a gas mask. The government-issued mask was the best protection he could find against hay fever. He didn’t care if he got strange looks, or even that one person called the police, thinking he was a spy.
Turing stopped, then reached down and re-adjusted the bike chain with a practiced ease. The old bike had a flaw in the chain that would make it come detached. Turing figured out it happened after a certain number of revolutions. Rather than get it fixed, Turing simply counted off the revolutions, stopped, and adjusted the chain, over and over.
As he fixed the chain, Turing noticed a wildflower growing on the side of the road. He studied the repeating pattern in the shape of its petals, wondering at the mathematical logic behind it. He plucked the flower, pocketed it, and hopped back on his bike, hoping to get to the office and write down his observations while they were fresh.
SFX: bicycle
Soon, he arrived at the front gate of Bletchley Park: English countryside manor, home of the top-secret program Ultra, and Turing’s new workplace.
He held out his ID badge for the guard, who looked confused. Turing remembered he was still wearing the gas mask and slipped it off.
Ah. Go ahead, Dr. Turing.
Turing pedaled to Hut 8, one of the many temporary buildings constructed to house England’s growing code breaking operation.
As he entered, he offered a distracted Good morning to his colleagues. They included chess whiz Hugh Alexander, statistics expert Jack Good, pipe-smoking former college dean and mathematician Gordon Welchman, and of course their “office girl,” but also a mathematics genius, codebreaker, and invaluable member of the team, Joan Clarke.
Joan stood and approached. Of everyone on staff, Turing was closest with her. They were friends, then more than friends.
Prof? We’ve got something.
Turing eyed the stack of papers in Joan’s hand
In here.
SFX: door opening and closing.
Inside Turing’s office, Joan eyed his teddy bear Porgy—and yes, 29-year-old Alan Turing had a teddy bear. He asked his mother for Porgy last Christmas, since he never had one as a child.
Well?
We’ve captured a U-Boat!
Turing forgot the flower in his pocket. Joan handed him the papers.
One of our corvettes hit it with a depth charge. The captain ordered them to surface and everyone abandoned ship. But get this—the captain forgot to destroy his Enigma. He tried to swim back for it and drowned! We recovered not just their Enigma, but their whole cipher book!
This was a breakthrough.
But before we go further, it helps to understand where the Enigma came from, why it was built, how it worked, and what Alan Turing and his colleagues were up against.
Before Enigma, encryption was done by hand with ciphers and code books. The more complex the cipher, the harder the code was to crack—but this also made it more likely for a human to make mistakes during encryption. Machines were needed.
Enigma was invented in Germany in 1918, originally to protect communications in the banking industry. Since it was battery-powered and portable, the German military purchased it and made several modifications to make it even harder to crack.
Enigma was essentially an electronic typewriter. Type a letter of the alphabet, and Enigme provided a different one.
Inside Enigma were eight movable rotors. Each one was carved with 26 grooves, one for each letter of the alphabet. Only three could be engaged at a time, which still gave 17,576 cipher combinations.
But the Enigma’s real innovation was its plugboard, or the nest of wires connecting the rotors to electrical circuits, like a telephone switching board. These further scrambled the message, giving Enigma 159 million million million possible cypher combinations.
We could go into the math, but we’d rather help you kill time than kill you with boredom.
Also…we couldn’t go into the math if our lives depended on it.
Bottom line, it would take a single person working by hand many lifetimes to decode just one Enigma message. Thousands were being sent per day.
But how did the Allies even know about this?
The Nazis used Enigma to encrypt their radio messages, which anyone could intercept, but nobody could understand. The only way for two Enigmas to communicate was if their operators were using the same rotor and plugboard settings. For security, the Nazis changed these settings every night at midnight. Every month, Enigma clerks received a list of that month’s Enigma settings.
So, even if you captured a working Enigma, unless you had that month’s encryption settings, it was useless.
In the 1920’s and 30’s, neighboring European countries watched with concern as the German military began using Enigma to conceal its communications.
One was Germany’s eastern neighbor, Poland. Led by mathematician Marian Rejewski, the Poles invented a machine that could crack Enigma—the Bomba. It likely got its name from the ticking sound it made, which resembled a bomb.
It took six Bombas working to crack one Enigma, via brute force. By 1938, Rejeweski and his team were able to decrypt certain messages from the Nazi military. But then the Nazis changed their Enigma settings—suddenly, instead of six, it would require 60. Well beyond Poland’s capabilities.
With a Nazi invasion on the horizon, the Poles decided to share their research with their allies. In the summer of 1939, the Poles smuggled a working Bomba to England, right around the time Alan Turing reported for duty. This would save Turing and his colleagues years of work.
With the Bomba, the Government Code & Cipher School set up its own project to break Enigma, called Ultra, and put Commander Alistair Denniston in charge. Ultra was based in an English country manor called Bletchley Park, equidistant from Cambridge and Oxford Universities, which would supply the mathematicians needed for the effort.
They had to move fast. On September 1st, Hitler invaded Poland, forcing the UK into the war. Three days later, Turing reported to Bletchley Park.
The sprawling compound was filling up with temporary buildings nicknamed “Huts.” Turing was assigned to Hut 8, which among other things was tasked with breaking the Nazi Naval Enigma.
Like we said, the Nazis didn’t use just one Enigma setting for all their communications. As Turing and the others at Bletchley discovered, there were different Enigma settings for the navy, army, air force, railroads, and other branches of the military and government—and this would only increase during the war.
The Nazi Navy, the Kriegsmarine, had the most secure Enigma with the most modifications, making it the hardest to crack. And the Kriegsmarine was the most dangerous threat to England and its allies.
The British nicknamed the Nazi Navy Enigma “Dolphin.” It was so difficult to crack that few other Bletchley codebreakers bothered. But Turing and another mathematician named Gordon Welchman made it their problem to solve.
Turing already had a head start thanks to the Polish Bomba, but the Bomba could only decipher simplistic Enigma messages weeks after they were broadcast. Too slow to help.
Enigma was essentially a primitive computer. It would take another machine, an improvement on the Bomba, to defeat it.
And if Enigma was a computer, that made Turing a hacker.
As we’ve seen on Modem Mischief, computer hacking is the process of probing a target computer for weaknesses and then exploiting them. This is essentially what Turing, Welchman, the Poles, and other cryptanalysts were doing—looking for Enigma’s weaknesses, then figuring out a way around them. Just like hackers generations later.
When Turing and Welchman began work on their new machine in the fall of 1939, no Enigma messages had been broken since 1938. But they saw a way to make the Bomba more efficient.
In cryptography, a “crib” is a word or phrase that’s known or assumed to occur in an encrypted message, which can be used to decode the rest. Turing and Welchman assumed that certain words were likely to appear in certain Enigma messages—a weather report probably includes the word “Weather.” A report on troop movements might include “General,” and so on.
These are called “probable words.” Turing and Welchman designed a new version of the Bomba that could guess probably words in encrypted messages. Once discovered, these words could be used to break the rest of the text.
They called their machine the “Bombe.”
But the first Bombe wouldn’t be operational for months. In the meantime, the Nazi war machine marched on–and the UK was in its sights. In April 1940, the Nazis launched an invasion of Norway, one of the UK’s key allies. During the battle, two Nazi battleships sank a British aircraft carrier—meanwhile the British didn’t even know their own carrier’s location.
The fall of Norway led to a series of parliamentary debates. Winston Churchill replaced Chamberlain as prime minister.
Unlike Chamberlain, Churchill was a former First Lord of the Admiralty and understood the importance of encryption and communications—especially naval ones. A year after taking office, Churchill personally visited Bletchley Park and met a (very nervous) Turing, encouraging him to continue his work. During Churchill’s ensuing pep talk to Bletchley employees, he would call them “the geese that laid the golden eggs and never cackled.”
Privately, however, Churchill was worried. Could Bletchley crack the most dangerous threat—the Nazi U-Boat fleet?
Turing and Welchman’s Bombe became operational in August 1940, but it still took painstaking weeks for the Bombe to cycle through the millions and millions of possible ciphers to unscramble a single message. Whatever intelligence could be gleaned from this was weeks out of date. They were back to where they were in 1938.
This…was a problem.
In early 1941, U-Boats sank an average of 200,000 tons of Allied shipping per month. If this continued, it would cripple England’s ability to wage war—unless they could break the U-Boats’ Enigma messages and avoid the U-Boats entirely.
In February 1941, around the time the Nazis invaded the Soviet Union, the Allies got a break. The Royal Navy captured a Nazi surface ship with an intact Enigma machine and a book of ciphers. This allowed Bletchley to decode the past month’s Enigma messages, which gave them actual recent locations of the U-Boats. Still out of date, but progress.
Turing needed more Bombes, but GC & CS and the Royal Navy were slow to build them. He came to dislike Denniston, whom he viewed as a functionary without the mathematical prowess to understand the job.
In his spare time, Turing continued mathematics research. He began plans to build a machine that could play chess.
He also met Joan Clarke. She was a brilliant mathematician who was nevertheless assigned to clerical work at Hut 8. Nevertheless, she quickly grasped Turing’s work on the Bombe and became an invaluable colleague.
They became close friends, even affectionate for each other. Turing told Joan about his sexuality, but she was unfazed. Soon, in the summer of 1941, Turing proposed marriage. Theirs wouldn’t be a romantic one, but that was hardly unusual for British couples in the 1940’s, who often married for duty. She accepted.
But after an unpleasant vacation to Wales, Turing broke things off. They remained friends. But with the war on, romantic love would have to wait.
By the summer of 1941, Bletchley finally built enough Turing Bombes to decrypt the Naval Enigma messages within a day of transmission—finally providing them with actionable intelligence. British shipping losses declined.
But this was still just one piece of Enigma’s puzzle. The Nazis were building hundreds of Enigmas with different settings all around Europe, and the same was true of Italy and Japan.
Bletchley Park had…sixteen Bombes.
Fed up, Turing, Gordon Welchman, and Hugh Alexander wrote a letter to Churchill, complaining about their government’s lack of support. When the letter arrived, Churchill immediately ordered his chief of staff to give Bletchley everything it needed.
In reality, it probably wasn’t enough. But two months later, everything changed.
SFX: Japanese airplanes.
Early on the morning of December 7th, 1941, Japanese fighter planes launched a surprise attack on Pearl Harbor, pushing the United States into the war—along with its military and industrial might.
Churchill knew they would win the war.
But Bletchley Park’s work wasn’t finished. Soon, the Nazis would introduce an even more sophisticated encryption machine that would come to be nicknamed Tunny.
As for Turing, the war would take him in increasingly unpredictable directions.
Act Three
Will someone tell me how in hell the Nazis added a fourth rotor to Enigma without us bloody noticing?
In early 1942, Bletchley Park cryptanalyst Hugh Alexander stood next to a chalkboard drawing of their next great threat: the Enigma M4.
Like we said earlier, the first Enigmas had eight rotors, of which three could be engaged at a time. But recently, the Nazis added another thin rotor, allowing four of the now nine rotors to scramble a message.
Alexander glared at the group, which included Gordon Welchman, Jack Good, Joan Clarke, and a few other members of the Hut 8 team—but not Alan Turing, for reasons we’ll get to.
Seriously? We’ve been cracking their messages for months and they never once mentioned it?
Finally, Jack Good spoke up
Actually…we’ve been reviewing the intercepted traffic from late 1941, and…we did find talk of a fourth rotor. But there were so many messages. We missed it.
Not good enough! We’re losing more shipping than we have at any other point in the war!
This was true. The Nazis had steadily increased their U-Boat fleet, and now that the fourth rotor made them invisible, the wolfpacks hunted with near impunity.
It would take Hut 8 a full year to crack the new four-rotor Naval Enigma, during which time the Nazis would sink 2 million more tons of shipping.
But big picture, things weren’t quite as bleak.
As we mentioned, Hut 8 was just one building at Bletchley and mainly specialized in the Naval Enigma. But many other huts at Bletchley were focusing on other Nazi Enigma settings, with much more success.
For example, Bletchley cracked all of the Enigma settings used in the African theater. With the intelligence gleaned from these messages, Bernard Montgomery defeated Erwin Rommel at the Battle of El Alamein in July 1942, keeping the Nazis out of Egypt and beginning the push to remove them from Africa entirely.
Churchill called the moment “the end of the beginning” of the war.”
There was also the American factor. When it came to codebreaking, the Americans were even farther behind where the British were when the Polish Bomba arrived in 1939. But thanks to British cooperation and American industrial might, that quickly changed.
Churchill shared many of Bletchley’s secrets with the Yankees, including the Turing Bombe. Soon, the Americans had plans to build 100 Bombes of their own.
Altogether, by the end of 1942, the Americans and Bletchley Park were able to crack 66 different Enigma key systems, which produced fifty thousand decrypted messages a month – one every minute.
The Nazis knew their Enigmas were being cracked, but they assumed this was the work of spies. Their precious Enigma was infallible, they thought.
This is just one of many mistakes the Nazis made while using Enigma throughout the war. For example, while Enigma settings were changed daily, individual operators would accidentally broadcast a message with the last day’s settings instead. They would then immediately rebroadcast it in the correct settings, giving the British two versions of the same text.
Or, when they added the fourth rotor in early 1942, many Enigma operators simply…didn’t bother using it, allowing Bletchley to continue breaking messages the old way.
As Commander Denniston later put it, the Nazi Enigma operators were “simple souls with childish habits.”
All of this—the turning tides in the war, the construction of many more Bombe machines, and Bletchley Park’s increasing ability to crack Enigma messages, meant that Enigma work was now beneath Alan Turing.
Partly this was personality. Commander Denniston was replaced by Edward Travis, a more effective administrator who recognized that Turing was more valuable as a researcher than a manager. Hugh Alexander took over management of Hut 8, and Turing was moved to a consulting role.
Turing didn’t mind. He didn’t care much for office politics, and this would allow him to pursue new challenges.
In late 1942, Turing was chosen for a special mission to the United States, liaison for the Government Code & Cypher School to the US Navy. He was to share all his knowledge about Enigma, the Bombe, and codebreaking—in reality, MI6 ordered Turing to lie about nearly everything.
Turing was a mathematician, certainly not a diplomat or a spy, but he did as he was told. Besides, the mission had another purpose, one which he was much better suited for.
In November 1942, Turing boarded the passenger ship the Queen Elizabeth for another voyage across the Atlantic.
Yes, the wolfpacks still hunted—more than 100 U-Boats now prowled the North Atlantic—and many remained invisible to Bletchley Park’s codebreakers. But the Elizabeth was faster and able to zigzag past them.
Turing arrived in New York City and took a train down to Washington DC for the diplomatic portion of his job. That finished, he returned to New York for the second purpose of his trip.
He reported to a 13-story industrial research facility with its own railroad line overlooking the Hudson River: the Bell Laboratories building.
Bell was founded by telephone pioneer Alexander Graham Bell, and the NYC headquarters developed everything from television to radar to even early video phones. These days Bell was working on projects with military applications, including work for the Manhattan Project.
Turing got a tour of the facility. On it, he came across a math problem on a chalkboard that stumped Bell scientists for months and quickly solved it. This was going to be a good fit.
Turing was there to consult on a project code named “SIGSALY,” a nonsense acronym. Bell called it “Project X.” And it was the closest anyone had come to an encrypted telephone.
It’s one thing to encrypt written communication, like an Enigma message. But encrypting speech is much more difficult. When people speak, we often use many more redundancies in words and phrases than we do when we write—which gives a codebreaker an advantage.
Think of an audio message like a series of spikes on a graph. Bell devised a way to use a voice encode, or vocoder, to essentially reduce the amount of information in an audio message from a continuous stream to a sampling, thus limiting the redundancies that were transmitted.
Turing tried to crack Project X’s encryption. After two months, he was satisfied it couldn’t be cracked. But Turing also spent this valuable time learning how Project X worked, which would prove invaluable later.
In March, Project X was finished. It was installed at the highest levels of the US government, including the White House and the Pentagon. It was also installed at the US embassy in London, but only a select few top English officials could use it.
Now, the most sensitive telephone calls could be secure. However, it wasn’t quite the triumph for Turing that it seemed. England still needed its own encrypted telephone.
In March 1943, Turing boarded a ship to return home and continue his fight. The speedy Queen Elizabeth was unavailable, so this time it would be an ordinary troop transport, the Empress of Scotland.
Weeks earlier, a U-boat sunk another transport, the Empress of Canada, and hundreds died. Turing would have known about this, but he made the voyage anyway.
To keep his mind off the danger, Turing studied Bell Labs’ handbook for its RCA Radio Tube. this would lay the groundwork for his next great invention—and obsession.
But even though Turing and Bletchley Park’s work to crack Nazi codes had begun to turn the tide of the war, the war was far from over. Thousands of combatants were dying daily on land and at sea around the world. Thousand more civilians were dying in their homes or Nazi concentration camps.
And just when Bletchley Park would make progress on cracking the four-rotor Enigma, the Nazis introduced another encryption system that was even harder to crack. It was nicknamed “Tunny,” and it protected the Nazi’s most secret communication.
The Allies would have to break Tunny just like they’d broken Enigma—before it was too late.
Act Four
SFX: Christmas carols
December 1951. Manchester, England.
Alan Turing walked along Oxford Street, just where it became Oxford Road. He looked through the shop windows at the items on display, thinking of what to buy his friends and family for Christmas.
He felt a bit depressed. Britain’s post-war austerity measures meant a meager display was on offer. But Christmas always depressed him anyway.
Turing wasn’t just here to shop. As he meandered, he noticed a young man with fair hair and blue eyes. Turing guessed he was about twenty. The man noticed him, too, and didn’t look away.
Oxford Street was what passed for the center of gay life in Manchester 1951, where homosexuality was illegal. It was a place where gay men could meet other gay men for clandestine hookups, often paid for.
Turing crossed the street and approached the young man.
Where are you going?
Nowhere special.
I’m Alan.
I’m Arnold.
Want some lunch?
Turing motioned over his shoulder at a nearby restaurant.
I’m famished.
Over lunch, Turing got to know young Arnold Murray, age 19. His father was a concrete layer who abused his mother. Arnold was thin, owing to his wartime malnourishment. During the war, he was sent to a boys’ camp in the countryside to avoid the bombing, but when he returned home after Victory Day, his father declared he was old enough to fend for himself and cast him out
He’d worked a series of odd jobs, including making eyeglasses frames, but now he was unemployed and crashing with a relative.
Turing told Arnold about his work, including his involvement in what he called the construction of an “Electronic Brain.” Arnold did once have an interest in science, and he was fascinated with Turing’s work, even if he didn’t quite get it.
I do have to be getting back to the office. But perhaps we could continue this conversation at my house this weekend?
Arnold knew what Turing was really asking.
I’d love to.
Turing was elated. But Saturday arrived, and Arnold never showed. Ah well.
A few weeks later, Turing was again strolling along Oxford Street when he again saw Arnold. Arnold looked embarrassed.
Apologies for not turning up. Something came up.
Not a problem. The invitation still stands.
This time, Arnold agreed with no hesitation, and the two headed back to Turing’s place.
The two men spent an enjoyable afternoon together, and promised to see each other again.
A few days later, Arnold was hanging out with another boy who frequented Oxford Street, Harry. He told him all about this mysterious college professor and scientist.
Harry was interested. It sounded like this Alan fellow had money. Harry casually asked where Alan lived, and got his answer.
A few days after that, Alan Turing cycled home from work to find his home broken into. He was horrified. Was this random—or was Arnold involved?
He picked up the phone and dialed.
Police? I’d like to report a burglary.
Little did Turing know, this phone call would doom him.
Next time on Modem Mischief:
-Alan Turing and Bletchley Park continue their fight to defeat the Nazis–unaware that spies are in their midst;
-Turing then plays an instrumental role in the birth of computers;
-But Turing’s personal life in bigoted Britain brings it all crashing down.
CREDITS
Thanks for listening to Modem Mischief. Don’t forget to hit the subscribe or follow button in your favorite podcast app so you don’t miss an episode. This show is an independent production and is wholly supported by you, our listeners and the best way to support the show is to share it. And another way to support us is on Patreon. Just go to patreon.com/modemmischief or click the link in the show notes. You can also support us through a paid subscription on Apple Podcasts. For as little as $5 a month you’ll receive an ad-free version of the show plus bonus episodes exclusive to subscribers. Modem Mischief is brought to you by Mad Dragon Productions and is created, produced and hosted by me: Keith Korneluk. This episode is written and researched by Jim Rowley. Edited, mixed and mastered by Greg Bernhard aka Or-Greg-Ano. The theme song “You Are Digital” is composed by Computerbandit. Sources for this episode are available on our website at modemmischief.com. And don’t forget to follow us on social media at @modemmischief. Thanks for listening!