Unbreakable--The Spies Who Cracked the Nazis' Secret Code Read online

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  TO MOM, WHO TAUGHT ME TO READ, AND DAD, WHO TAUGHT ME TO SPEAK

  AUTHOR’S NOTE

  DECIPHERING IS THE CORRECT TERM BUT WE INVARIABLY SPOKE OF DECODING.

  —HUGH ALEXANDER

  A CODE IS a substitution: replacing one word, letter, number, or symbol with a different word, letter, number, or symbol in order to hide the original’s meaning. When spies give each other secret names to hide their true identities, this is a code. A cipher, on the other hand, is a more complex equation of variables and manipulations. This would be like when you and a friend decide to write a note to each other and agree to change all your a’s to b’s, b’s to c’s, c’s to d’s and so on, so that none of the words make sense to anyone but you two.

  Most of this story is about ciphers and the ways in which the ciphers were broken, or deciphered. Yet, as Hugh Alexander said above, we often slip from the correct to the common.

  The terms code and cipher, decode and decipher, as well as codebreaker, cryptologist, cryptographer, and cryptanalyst are used interchangeably throughout this story.

  ONE

  TRAITOR

  1929—Warsaw, Poland

  THE BOX ARRIVED on the last Saturday in January.

  Business in the Polish customs office went on as usual, the rhythm of sorting and inspecting undisturbed by the heavy package with a German postmark. In fact, the officer in charge had nearly finished when the urgent request came in.

  Return it immediately, the German embassy demanded. There had been a mistake. It was a German package, intended for a German recipient. It should never have been sent to Poland. Cease operations and give it back.

  Now, that made the customs officer pause.

  He did not return the box. He opened it.

  A polished surface gleamed in the light. Along a hinge in the back, a wood cover opened to reveal something almost like a typewriter. Elevated keys were arranged in three rows along the bottom, each labeled with a letter of the German alphabet.

  But that was where the similarity to a typewriter ended.

  There was no inked ribbon, no carriage in which to hold paper to type a letter. Instead, the top of the box was filled with small circular windows arranged in three rows identical to the keyboard below; each window contained a single letter printed on translucent material.

  If the customs officer pressed a key, instantly, in the top rows, one letter began to glow. As soon as he released the key, the light went out. If he pressed the same letter key again, an entirely different light and letter shone back.

  Quickly, the Polish customs officer made a call. Across town, two men secretly working for the Polish cipher agency understood immediately and rushed to the customs office.

  Over the next two days and through the next two nights, the men disassembled, examined, and reassembled the machine.

  By Monday morning, they had meticulously put every part back into place. They repackaged the machine in the same box and wrapped it in the same brown paper in which it had arrived.

  Poland would return German property to Germany, as requested. The delay, inevitable, due simply to the weekend.

  No one in Germany suspected a thing.

  Enigma in use.

  [Bundesarchiv, Bild 183–2007–0705–502 / Walther / CC-BY-SA 3.0]

  Two years later, Sunday, November 1, 1931—the German-Belgian border

  Hans-Thilo Schmidt rushed through the doors of the Grand Hotel in Verviers, Belgium, two hours late. He never saw the man sitting in the lobby waiting for him.

  To this man, Schmidt was an ordinary German of average build, wearing a dark hat and dark coat. Schmidt was red in the face and puffy around the eyes, both traits the man watching him had been expecting. He knew that Schmidt’s train was late, and Schmidt sweated and grew flushed as he hurried to make up lost time. Schmidt’s puffy eyes had been expected as well. The people this man watched often suffered from sleepless nights. Treason was never an easy decision.

  Not that Schmidt would have noticed the man even if he’d been relaxed and alert. Hans-Thilo Schmidt was far from experienced in spy craft. Last June, when he had first decided to trade secrets for money, he simply walked into the French embassy in Berlin. Incredibly, he plainly announced his intent to sell information to the French government. Without cover and without any personal security, he asked whom he should contact in Paris to do so. Somehow, he had neither been arrested by the Germans nor ignored by the French.

  Now, five months later, the German Schmidt was about to meet face-to-face with a French intelligence officer. Hans-Thilo was nervous, and he was late.

  At the front desk, the receptionist checked Schmidt into a room already reserved for him and handed him an envelope along with his key. He entered the elevator, and as the doors closed in front of him, the man watching him from the lobby saw him rip into the letter, which read “You are expected in suite 31, first floor, at 12 noon.”

  At precisely noon, as the letter instructed, Schmidt knocked at suite 31.

  The door opened into another world where time seemed to slow as an older woman with elegantly styled white hair greeted him and asked him to wait in the comfortable, richly furnished room. Soft music played gently over the radio. An inviting arrangement of liquor and crystal glasses was set out next to a display of fine cigars. Gratefully, Schmidt eased himself into a plush chair.

  “Guten Morgen, Herr Schmidt! Hatten sie eine gute Reise?”

  Schmidt jumped as an unfamiliar voice boomed at him in German. An immense man with a shaved head came through a doorway, entering the living area through another room in the suite. Round, dark spectacles framed icy blue eyes that pierced Schmidt with an unwavering stare.

  “Sit down, please,” the man continued. “How are Madame Schmidt and your two children?”

  Schmidt, already on edge, tensed more. He was currently living alone, and his wife, son, and daughter were living with his wife’s parents.

  “I know,” the man said, cutting Schmidt off before he had a chance to answer. “You will want to bring your family back together soon and resume a pleasant life. That, of course, depends on you. We will assist you if your cooperation proves fruitful to us.”

  Taking an offered glass of whiskey, Schmidt sat back down.

  The man confronting him became even more serious. “Your resourcefulness last June in Berlin was quite exceptional and effective, Mr. Schmidt. Quite fortunately you happened upon an official of the French embassy who … was inconspicuous. What would you have done if he had thought you were an agent provocateur and called the police?”

  This pushed Hans-Thilo Schmidt to his limit. “I thought you would understand!” he snapped, defiant. “If you feel this way, my only option is to withdraw. Others will know how to interpret my motivations and the r
ationale of my propositions.”

  “Easy now, Mr. Schmidt,” the man responded. “We appreciate your initiative and the benefit we can gain from it.

  “Let me be frank,” the man continued, “my name is Lemoine, and I represent the French Intelligence Bureau.”

  Rodolphe Lemoine was the top recruiter and handler for the Deuxième Bureau, the branch of French military intelligence charged with keeping an eye on hostile countries. He was an expert at bringing “assets,” people with information and secrets that France needed, into agreement.

  One of Lemoine’s colleagues had described him as “an amazing person who knows as much about how to compromise a minister as he does recruiting a general. He’s as much able to get his hands on a safe as acquire a Yugoslavian passport for you in twenty-four hours.”

  “That is to say,” the same colleague had continued, “you must keep your eyes open and ensure you are not ensnared by the undeniable charm of the man.” To Lemoine, another person’s weakness was a benefit to be exploited, and he used every advantage, both those that were legal and those that were perhaps not.

  This world of secrets and spies was, Lemoine felt, a line of work that benefited from a display of opulence. Money spoke of confidence. And confidence made people comfortable. Comfortable enough, Lemoine knew, to betray their country.

  Today’s meeting was typical of Lemoine’s style: the largest suite, in the most expensive hotel, stocked with fine liquor and large cigars.

  “You must have undoubtedly understood,” Lemoine continued to Hans-Thilo Schmidt, “that we would have already performed a background check on you. Tell me in detail who you are, what you do, and why you are turning to us.… But first, would you like another glass of whiskey?”

  With a topped-off glass and now a cigar, Schmidt pulled out his identity cards in silence.

  SCHMIDT, HANS-THILO

  BORN MAY 13, 1888

  Occupation: Beamter im höheren Dienst, Chiffrierstelle [senior civil servant at the German cipher office]

  Whiskey before lunch loosened Schmidt’s tongue, and he began to speak.

  He had not always been poor. His mother had been born a baroness. He had married a wealthy woman, and his in-laws gave him a house and some land just outside of Berlin as a wedding present. But then Germany’s economy declined, and the money went with it. Even with a university degree, finding a career as a chemist was impossible as Germans throughout the country all scrambled for jobs and money. His injuries from the First World War eliminated any possibility of a position as a soldier, too.

  Hans-Thilo’s brother, on the other hand, was quickly rising through the military ranks, and he managed to use his influence to find Hans-Thilo a job as the assistant to the head of the German cipher office. Mostly, Hans-Thilo arranged appointments and kept track of paperwork. Yet he freely came and went through his commander’s office. An office that contained a safe.

  It was widely known that the Germans had developed a new type of cipher. Not that anyone in Germany had said as much; they didn’t need to. It had become obvious the moment the rest of the world had stopped being able to read their transmissions.

  For years, nothing had worked to break the new code; they had never seen a cipher like it before. The Germans were using a mechanical device—the Enigma machine—to rearrange letters of a message into an untraceable pattern. The result was a cipher more complex than any before it. No one could break the German Enigma.

  Decoding the cipher and accessing all of the political and military intelligence within its messages would give an enormous advantage to anyone opposing Germany. And though there was currently a fragile peace in Europe—it had been over a decade since the end of WWI—signs of war were once again on the horizon.

  As a German, Schmidt knew that other countries, France chief among them, were greedy for help from someone on the inside. Someone like him.

  The safe in his commander’s office held all the information needed to crack the Enigma cipher: manuals, schematics, codebooks, updates, and plans. Hans-Thilo had access to it all, and he was prepared to deliver it to France. For the right price, of course.

  Schmidt’s salary could never cover anything more than living expenses. And Schmidt had many debts.

  “I’ve been desperate,” he said, finally answering Lemoine’s question. “Believe me, Mr. Lemoine, the reliability of our Enigma is total, absolute.”

  Lemoine knew enough to agree.

  “Return here next Sunday with as much intelligence as you’re able to provide,” said Lemoine. “How much do you earn now?”

  “Five hundred Reichsmarks a month.”

  “Here is triple that amount to compensate you for this first assignment, and to assist you with getting back here on Sunday.”

  The value of the intelligence Schmidt brought next weekend would determine how much he would be paid then.

  * * *

  Rodolphe Lemoine arrived back in Verviers the next Saturday, one day ahead of Schmidt, and he did not come alone. If Schmidt really did bring information as substantial as he had claimed, Lemoine needed to be prepared. This time, the Deuxième Bureau had also sent a photographer as well as a senior officer, Captain Gustave Bertrand.

  Bertrand had spent his life around codebreaking, though he couldn’t untangle a cipher to save his life. He preferred to learn secrets a more discreet way. By enabling agents and spies, forging alliances, and purchasing foreign codebooks outright, Bertrand helped to break codes without sitting behind a desk. Lemoine had promised him a windfall.

  The next morning, they waited. While Lemoine was downstairs, “settled in like a prince, as usual, in suite 31,” Bertrand and the photographer stayed in the two other, much smaller and simpler, rooms.

  Schmidt was due at nine o’clock.

  Finally, at ten, the phone in Bertrand’s room rang.

  “We apologize for the delay,” Lemoine said. “Can you come down?”

  Bertrand rushed out, anxious and impatient, while the photographer stayed with the equipment.

  Cigar smoke filled the room, and Schmidt again held a glass of whiskey. When Lemoine made introductions, Schmidt bowed to Bertrand. Though Schmidt wore old, worn-out clothes and dingy shoes, Bertrand remembered that “his blue eyes were beautiful, they shone with intelligence.”

  “Mr. Barsac,” Lemoine began, calling Bertrand by his alias, “you are, I believe, going to be satisfied. Mr. Schmidt did not hesitate to entrust us with a few documents.”

  Schmidt insisted that he had meant to bring more, too. The list of daily settings for the Enigma, called keys, was usually in his commander’s safe, “but my chief left it with one of my colleagues for binding, and I dare not ask for it.” He promised to bring it next time.

  Lemoine handed Bertrand a folder, thick with hundreds of documents. “He will need them back by no later than 3 P.M. in order to catch the train back to Berlin.”

  Bertrand took the stairs up to his room three at a time. While the photographer recorded every page, Bertrand read the material. Each sheet was marked GEHEIM—SECRET—and for good reason; Schmidt’s documents explained exactly how to set up and operate the German army’s Enigma machine.

  Before he had left the room, Bertrand had pulled Lemoine aside to discuss payment for their newest spy. At first, Bertrand suggested 5,000 Reichsmarks (about $63,000 in 2022), nearly a full year’s salary at Schmidt’s regular job. Lemoine, sensing just how excited and impressed Bertrand was, immediately doubled the amount, with the same to be paid again if Schmidt continued to bring information. It was an expensive exchange, but everyone walked away from the meeting satisfied.

  Lemoine had his spy. Bertrand had his information.

  And Schmidt now had a code name: Asché.

  * * *

  Hundreds of stolen documents! More to come! Bertrand returned to the Deuxième Bureau triumphant. Later, he wrote that Schmidt had just provided him with “the thread that would permit us to get to the heart of the Enigma mystery.”

&n
bsp; But Bertrand had not fully grasped the complexity of Enigma.

  Codebreakers at the Deuxième Bureau had already worked for years to translate Enigma messages. Their efforts had met with so little success that one of Bertrand’s colleagues summed it up: “Mechanical encryption is impenetrable. Why waste any time on it?”

  When Bertrand returned to Paris and handed over the photographs of the manuals, the material did not change the codebreakers’ minds. It was secret information, sure, but it wasn’t enough to decipher Enigma messages. Schmidt’s manuals explained how to encode messages, not how to read anything that had been intercepted. There wasn’t even enough information to explain how to re-create the Enigma from scratch. Without an Enigma machine in hand, this new information was useless.

  Crushed but not defeated, Bertrand decided to see if the information could help his colleagues in England. He gave the secret documents to the French station of the British intelligence service. The codebreakers there read the assembled set and even sent the photographs to other codebreakers back home in England.

  The verdict stood: Schmidt’s information was not enough to break Enigma. The English and the French had given up.

  But Bertrand knew there was one more country, one more cipher bureau, that was particularly interested in Enigma.

  Bertrand began packing for Poland.

  TWO

  THE STARTING LINE

  December 1931—Warsaw, Poland

  POLAND HAD TROUBLE brewing on either side. Sandwiched between Germany to the west and the communist threat of the Soviet Union (USSR) to the east, it was imperative that Poland understand what its enemies were thinking and planning.

  “The only ones who are truly passionate about these [cryptography] problems are the Poles,” Captain Gustave Bertrand later said.

  Now, standing in front of the Saxon Palace in Warsaw, holding his diplomatic bag filled with Asché’s documents firmly in hand, Bertrand put his last hope in his friends at the Polish cipher office.