A cryptographic machine for the sake of secrecy – in Hitler’s war. Of all those who tried to crack the machine there was only one who succeeded – alone, with pen and paper. G for Secret Oslo, April 1940. Nazi Germany has struck against Denmark and Norway. German commands echo over Karl Johan street. Copenhagen and Oslo have been taken by surprise. More capitals are next in line – the only question is which ones. Sweden on alert. It is Norway on the other side of the bridge. Is this the way the Germans will come? Or won’t they? Nobody knows. What if you could read the messages from Oslo, those we agreed to let the Germans send via Swedish lines. But they look like this when the Telecommunications Authority and the Defence Headquarters succeeded in tapping them. I answered a small ad in the newspaper Svenska Dagbladet, the fall of 1940. – They advertised for you?
– “Young lady, skilled in languages, shorthand and typing wanted.” I was called to a job interview at an insurance company. I was later told that the Defence Headquarters had rented a room there for security reasons. – You did not know what it was about?
– No. Eventually the Defence Headquarters phoned me and I was called to an interview. Me and another girl were picked out of 28 applicants. – Unemployment was high.
– Did you know what you would do? -No. It was very secret everything.
-What did you get to do? You didn’t know what encryption was? -No I did not know that. A colleague thought she would start working at the Gunpowder Department. It was called the Cryptology Department. (gunpowder – krut, crypto – krypto) It was a condemned building that the state rented for 300 SEK a month. You weren’t allowed to slam the doors because it caused the plaster to fall off. And there was a strange smell in the rooms. The former tenant had put rotten fish behind the stoves. I suppose it was reprisals or something. – How many worked there?
– It swarmed. The back building was condemned – but there we sat. It was crowded and it was cold by the window, and warm by the stove. But it didn’t do anything. You had no pretensions. We sat in a small one window room with two masonite table facing each other. We sat there seven or eight of us, then there was no more room. It didn’t matter either. All kinds of people were recruited to the Defence Headquarters Cryptology Department. As long as they were talented. Åke Lundqvist, born deaf, was one of them. This is one of the species that had its own chronology here on Öland. In earlier years it was seen mostly on central Öland. It has retreated northward and have disappeared in the southernmost part of the island. Throughout his professional life Åke Lundqvist had cryptanalysis and codebreaking as his profession. But he was also a professional botanist and expert on the flora of Öland. And member of the national team in correspondence chess, with a fourth place in the World Cup. Nowadays he is mostly engaged in translating German 1800-century poets. Like Friedrich Rückert, and others. I have met many highly talented people but only one genius. Who that was, I don’t have to say. “The only genius” – Arne Beurling. Professor of mathematics at Uppsala and employed by the Defence Headquarters crypto department during the war. Those who worked close to Beurling tell the same kind of story about a man that God did not make any copies of. He was a very complicated man. It is precisely the empathy and emotional involvement that strikes one the most. He had an intense gaze as if coal fires burned in his face. He had a relationship with mathematics which was mysterious. It was as if he had a direct line to God with knowledge that we had not. The war drags on, it will be Brussels, Amsterdam and Paris for Hitler’s troops. Not Stockholm – yet. In the summer of 1940, Sweden is one of the few Western European countries that haven’t been invaded. All the time the stream of encrypted messages between Oslo and Berlin grows. There are German signalmen at Akershus and other German headquarters in Norway. They tap out telegrams on machines designed to ensure that the encrypted remain encrypted and unreadable until it reaches the addressee. Those who used these devices typed in plain text on the keyboard and the receiver used a similar apparatus and immediately received the message as plain text. On the line between it was encrypted. For the old cryptomachines a telegraph operator had to transmit the encrypted telegram and another one receive it before it was decoded. In the telegraph station in Gothenburg, Sweden taps the German traffic. From here it goes to Stockholm, where the material comes out on thin paper strips from a set of teleprinters. – It came out on a strip of paper from a teleprinter on Karlaplan 4?
– It came out on a strip of paper from a teleprinter on Karlaplan 4, yes. – What did they look like?
– They looked like this example. It was pasted strips on a Quarto format, which was the standard at the time. The strips were pasted like this. At the hight there came 10 km strip per day. Note per day, it’s quite a lot. This is what they looked like, the strips with encrypted German text pasted on sheets and placed in bundles – day by day. The bundles were labeled with date and stored in a closet at Karlaplan 4. Here they lay when Arne Beurling arrived. He had been brought from Uppsala to Stockholm to crack the German machine. The first thing he did was seek out a material that was registered as correctly as possible – but at the same time limited. In the end he chose to concentrate on the German crypto texts of 25 may 1940. I asked Beurling once: How did you actually deal with the German G-printer? “Well,” said Beurling, “you knew it was a five point alphabet.” “As such it can can’t be manipulated in so very many different ways.” “You try, you assume an exchange of characters.” “You think you are a bit on the way, but it’s not enough.” “Then there is the next possible step that this exchange of characters is combined with a displacement relative to them.” And so it was. I said, “That I understand enough.” “But shouldn’t you write down in detail how you worked?” “Well,” said Beurling. “A magician does not show how he works.” And that was that. It was like this Beurling sat and worked to find a way into the German cipher. He wrote all the messages from May 25 by hand on large sheets of paper and tried to imagine how the German machine was designed and how the signalmen worked. He assumed that each character corresponded to signals of five pulses according to the teleprinter alphabet and that pulses had been scrambled in some way in the machine. He discovered pretty soon that the German signalmen were inexperienced and had poor crypto discipline. They sent several telegrams on the same key. It gave him the first ways into the material. The characters the German signalmen typed on the G-printer were as predicted converted to teleprinter signals with five electric pulses, positive and negative. If you wrote an A the signal was two positive and three negative pulses. It can be written like this at the top: with two ones and three zeros. This is the teleprinter alphabet, letter by letter – 32 different combinations. Between each word the signalmen made a double space. It was these characters Beurling began searching for. The G-printer used a method for initial encryption that long had been known to Beurling and other cryptanalysts. It added, superimposed, two-character combinations using binary addition. This is how you use binary addition. Zero plus zero is zero. Zero plus one is one. One plus zero is one. One plus one is zero. Only ones and zeros. If you take the letter A (11000) and overlay it with the five pulses for R (01010) … … you get 10010 that correspond to the letter D. D is thus the crypto sign for A. You have written A, but for an unauthorized person it reads as D. So far, it was pretty basic by Beurlings standards. But the G-printer was much more complicated. Beurling saw that the machine changed the cryptographic characters yet again, probably by scrambling the five pulses. It would turn out that the G-printer had ten “key wheels” of different circumference. On the smallest pinwheel were 47 pins, which were positive or negative, one or zero, in irregular sequence. The second pinwheel had 53 pins and the tenth 73. The wheels were set to the initial position with different code keys and connected with the rest of the machine by patch cables. The connections could be varied at will and the Germans used to replace the wiring diagram at least weekly. Of these ten ones and zeros, the five on the left were used for overlay. This is the starting position, writing haven’t started yet. Now if you press a letter on the keyboard, an A for example, it is added with the numbers above and you get the first crypto character. But it is only half way. Now comes the new and cunning about the G-printer. The five zeros and ones of the remaining wheels are used for “permutation”. The five pulses will open and close relays, a kind of switches. A switch becomes active if it is affected by a one, but passive by a zero. Now the zeros and ones we got in the first cryptographic version pass these relays on the way to a new location. The one in the first position hits an active switch that takes it to track 2 that it follows to the next switch that is active. The one goes up to track 3 and the third position in the final cipher. The zero in the second position is switched down to track 1, then to position 5 via the next active switch. The zero in the third position passes a passive relay, but is then switched down to track 2. And then the next two, one and zero, fall into place. The final crypto, 00110, gives the letter N. The A that was typed becomes an N until the message becomes plain text in the recipients G-printer. This is what happens when the signalman type a character on his G-printers. As soon as he has done that, each of the ten wheels move to the next position. The ten wheels in the G-printer delivers numbers in an almost infinite variety. It is a eighteen digits long number, the steps G-printer can go before a certain wheel alignment will return. Arne Beurling had never seen a machine like the G-printer. The only thing he had to start from where the encrypted strips. He had no computers available. He had no staff that calculated for him. It took him 14 days to crack the G-printer crypto. Alone, with a graph paper and pencil. So the information began to flow. Suddenly the ones at Karlaplan 4 knows what the Germans are doing in Norway. Details of weaponry and transports, transfers and troop movements. Thousands of cracked telegram provide invaluable information. While the cryptography department is counting German bombs the code-cracking is expanded. We used large sheets of gridded paper where we wrote the German telegram traffic. After receiving today’s key we decrypted the telegrams, letter by letter. You must still have had some kind of training, it was five-digit numbers … – Did you know anything about encryption?
– No, I had never heard of it. It was new to me. But it was a very easy work really to fill in after the key. – Did you get the plaintext then?
– Yes, it became plaintext. – You were the first person in Sweden who found out what the telegram said?
– Yes, we were a bunch of girls who wrote … – Was it exciting?
– Yes, a very exciting job. This is what it looked like, the big squared sheets where Birgit Asp extracted the plaintext. Letter by letter. Dort, Krieg, Kiel … After only a few weeks Beurling had sketched a machine that did this work. A Swedish copy of the G-printer. An “app” as it was called. Built, maintained and rebuilt by engineering genius Vigo Lindstein. The first app he had constructed malfunctioned quite often, then we summoned engineer Lindstein. He looked very worried when he arrived but he had the patience of an angel. One evening we called him. And he came in, wearing a tuxedo, from a celebration dinner and fixed the machine. This is what it looked like, Vigo Lindsteins app. A small marvel of engineering. The wheels were set each morning, then you just entered the crypto text and out came plaintext. Though the plaintext was not always so obvious and easily interpreted as one could wish. – You must tell me what “trimming” is.
– You got the strips as they looked when they came out of the machine. They were passably readable. You would take them up to scatch. You would remove errors that were obvious and simply edit, insert new paragraph, capitalization, punctuation and such. Then you would also in some cases interpret, or rather reproduce what the station signals meant. – You must be good at German to be able to have that job?
– Yes you have to have a proper knowledge. It wasn’t possible only with grammar and a dictionary. In the early morning hours of June 22 the German army attacked on a broad front to repel the Bolshevik traitors threat to the Reich and Europe. June 22, 1941 Germany attacks to the east, towards the Soviet Union. The most violent outbreak of war ever seems to come as a surprise in Sweden But Operation Barbarossa is no surprise for the government and the military leadership in Stockholm. Reports from the Cryptology Department has told about German troop movements towards the northeast, about a marked interest in northern Finland and the roads towards Murmansk. An immense suffering faced by the Soviet Union. Russia is on fire. It is not far from Sweden. But the cracked telegrams give us at least a few weeks of security. In June 1941, when I was writing my strip produced German plaintext. It was saying that the Germans would get double pay when they entered Russia. And I was the first person in Sweden who knew. It was very nerve-racking to know about such a great historic event in advance. It was here on Blasieholmen in Stockholm the Germans had their legation during the war. To here came the political instructions from Berlin. Here the diplomats and the military met. Here resided the German Minister, Prince of Wied. He also used the G-printer that sent and recieved poltically sensitive information. It was important to examine the reports Wied sent to Berlin and clarify oneself, the times when the minister misunderstood what the Swedes said, which was quite common. Hitler’s plans for Sweden, however, never found its way into the G-printers’ telegrams. That uncertainty you had to live with. Here is a funny thing, in the middle of everything. The complaint. The watch officer has written there. “Complaint”. “Pasted wrongly 6/3, about 15 pages, Miss Bengtsson”. “According to information she have in a fortnight not yet learned to paste.” “Information on these pages have been lost.” “Make sure that she is not allowed to paste in the morning when she arrives at 10.” “B. should immediately be terminated!” He must have been angry… It was not only miss Bengtsson who got in trouble. One evening there was a falling out between the heads of then Cryptology Department. Beurling who mostly were in Uppsala happened to come down to Karlaplan 4 the evening Yves Gyldén appeared there, the 30’s big crypto expert in Sweden. Gyldén was a fanatical rugby fan, but it did not help against Beurling. The next afternoon when I came up after eating Gyldén sat and worked … with plasters and generally looking gloomy. He did not look up, but greeted kindly: “Hello, hello, sit down.” It lasted a while. We sat at the table across from each other and I said jokingly: “Have you shaved a bit hastily?” I knew it was not so, but I didn’t understand. “No,” said Gyldén.
“I’ll tell it like it is.” “I and Beurling made up last night.” It was just like school boys: They had had a fight. There were not many more evenings for Arne Beurling in Stockholm, it was mostly Uppsala henceforth. It had not so much with Gylldén to do as with the leadership of the Cryptology Department. Beurling was not of the kind the military bureaucrats liked. To put it gently. He took a little too much liberties. His private life had perhaps not as much to do with it. But Beurling was also careless with all the secrecy surrounding the operations. Yes, he was not averse from certain aspects of life. As…? – Is that off the record?
– No nothing is off the record. – Then I’ll be careful … It has its great importance when it comes to assessing him as a person from the Defence Radio Establishments point of view. – There was a falling out between him and the Defence Radio Establishment.
– Why? There were three or four reasons. The first, I have already answered that it must be off the record, and because it is not approved… The second was… that the Defence Radio Establishment’s management or Crypto department management… It was Thoren, Rossby and Kempe. A rather unfortunate combination that put their stamp on the Swedish codecracking organization the first five or six years. They thought Beurling should work by the clock. Not at the Defence Radio Establishment, but at home. So that didn’t work. German troops in Russia, not far from Leningrad. The German telegrams in late autumn 1941 gave intimate details. Not least, about the war in the north, about bombing target and German attack plans. The information was forwarded to the Foreign Ministry and the Defence Headquarters. This is how secret cracked telegrams looked when they left Karlaplan 4. They were of tremendous importance for Sweden. However, knowledge of them reached both the Soviet Union and Germany, and that long before the war was over. It was the Russians who got wind of them first. They got photocopies of them, even. The despatch-rider at Karlaplan 4, Allan Nyblad, provided the Russians with them. He was a Communist, and had discovered what he was delivering, and thought; There is a nation that can really benefit from this material, and it is the Soviet Union. So he made contact with the Russians. And they were obviously delighted because it was an incredible material, and they got it for a long time. But then Allan Nyblad became involved in a abortion scandal. He was sentenced to two years’ hard work and disappeared. It caused many gray hairs in the Sovjet legation – KGB or GRU – probably GRU. They tried to get hold of someone who could resume the tours with the material. They told the brother, Knut Nyblad, to apply, but he failed the personnel control. He had no chance. Then they sought contact with the person who got the job to recruit him. But that man talked with his managers. What was said I do not know. He came to Police Superintendent Thulin and talked about it. He received orders, probably in consultation with the Defence Headquarters, to continue to distribute messages. But now they started to make special messages, which were not true. He was distributing game content to the Russians. They did not get the real ones. But it looked exactly like the real ones, the same forms and everything. The texts went into the air from the Russians transmitter, and they were intercepted. That is what made it possible to eventually crack the Russian code. The Nyblad affair ended with the two brothers receiving long prison sentences. Fortunately nothing was leaked about what was in the despatch-rider portfolio, the Russians kept quiet for obvious reasons. But the Germans would eventually find out from elsewhere. It burst in June -42 when the Germans were informed from the Finnish side. How did the Finns find out? The story goes, that one of the Finnish military in Stockholm had seen one of these telegrams on a table in the Defence Headquarters. The Finnish military enjoyed great freedom of movement in the Defence Headquarters building… I think one may say. So perhaps the most important war secret in Sweden was left so a Finnish attache could see it? Yes there has been talk about a military attache. That it was laying on the table when he made a visit. And then they informed the Germans. They would have felt compelled thereto. The Germans knew that the Swedes were strangely well informed about their troops in Finland. They went to the Finns, and they said: “We have not said anything, the Swedes are reading this right out of your telegrams.” -Have Finns said anything about this?
-No. The leak from Finland was the beginning of the end for cracking the German cipher. One of the Germans’ first steps was to move as much as possible of the traffic to lines going around Sweden. At the same time they began to construct new, even more complex machines. They put in a new crypto machine of G-printer type in July, and it was cracked in about a month. Sweden had now built up the entire interception apparatus and apps. It was well equipped, and solved… For example, one day in October there were sent 678 telegrams in one day. That was a lot. But it was stopped at some time? Yes. In early 1943, it quickly turned out that the Germans’ counter-measures had started to take effect. It was more than a year of war and devastation left when the information from the German G-printers began to dry up to finally cease. But those days were over, when Nazi Germany was a threat to Sweden. The German cipher was not as important anymore. It was time to turn the interest elsewhere. It’s been 50 years, half a century, since Åke Lundqvist and Arne Beurling worked together with one reluctant cipher after the other. It is a long time. But until now the classified stamp has kept its bright red frames over wartime archives binders at the Defence Radio Establishment. And yet no one has written the story of the code-breakers, the military and Arne Beurling. Is there really any institution in this nation that has yielded as many professors as the Defence Radio Establishment? I don’t know. Are they many? At least every other of the better boys who were in brought in during the Second World War has continued on that path. Must be well over thirty. Arne Beurling was one of them – the only one of the thirty who was a genius, according to Åke Lundqvist. It took Arne Beurling a fortnight with pen and paper, to crack the encryption machine … … that German Siemens used a good bit of the thirties and its best engineering and cryptography experts to construct. A few years after the war Arne Beurling left Uppsala and became a professor at the Institute for Advanced Study at Princeton, USA. There, he later took over the office Albert Einstein once had. It was just wrong in some way for him to live in the United States. He was the most Swedish person I have ever met. The Swedish nature lived in him. The Neck (water spirit) was his cousin in some way. Arne Beurling portraied by Christer Olsson.