World War II Hackers

Stalin's best men, armed with paper and pen

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The use of encryption to secure sensitive data from unauthorized eyes is as old as human communication itself. Before the relatively new method of computerized encryption software converting data into a format unintelligible to anyone lacking the necessary key for its decryption, for a long time there was pen and paper and the human brain doing quite a bit of work. Up until the 20th century encryption had to be done literally by hand, to then be transmitted in paper form, via telegraphy or radio. In this context, encryption of data has always been of special importance during times of political conflict and war; subsequently, it saw its major developments during those times in history. This talk will examine and explain common hand encryption methods still employed today using the example of one very successful Soviet espionage group operating in Japan in the 1930s and 1940s: the spy ring centered around Richard Sorge, codenamed “Ramsay”.

In the summer of 1938, the Japanese Secret Police started to notice mysterious radio transmissions emanating from somewhere in the Tokyo area. These transmissions, consisting of seemingly meaningless groups of digits, seemed to be directed towards the Asian mainland; neither the Secret Police nor the Japanese Communications Ministry and the Communications Bureau of the Governor General of Korea were able to pinpoint the where and from more precisely. It wasn't until 1941 that Japanese authorities uncovered the full scope and meaning of these messages – by accident and at first disbelieving what they had unearthed.

The seemingly gibberish radio transmissions did indeed emanate from the heart of Tokyo and, as it turned out, were received in Vladivostok and passed on to Moscow, to be presented to Stalin himself. Decrypted, they contained vital information about secret German and Japanese plans, even the date of the German invasion of the Soviet Union. This information had been gathered by Richard Sorge, a German citizen with a colorful personality who had infiltrated the small German community in Japan under the guise of a journalist and even gained the friendship and trust of the German ambassador, giving him access to any information available inside the embassy of Japan's ally.

In Japan since 1933, Sorge had built a spy ring around a small group of confidantes: a Japanese journalist with connections to powerful Japanese political circles, a French-Yugoslav communist, and a German radio technician, Max Clausen.

Clausen's technical knowledge proved vital for the group's success: he was able to build a transmitter and receiver capable of reaching up to 4,000 km from scratch, using parts available in Tokyo shops without raising suspicion. His radio station was fully portable in a large briefcase and assembled in under 10 minutes.

The dispatches transmitted to the Soviet Union by Sorge's group were written in English and then converted into digits using a straddling checkerboard and, to scramble the content even more, a book cipher, using pages from a statistical yearbook as the key. The Japanese authorities were not able to decipher the messages, Sorge's encryption method remained unbroken until Max Clausen explained it himself after his arrest in 1941.

The historical importance of Sorge's espionage material remains a controversial issue among historians; some call him the greatest spy of all times, some argue that since Stalin did not trust his information, Sorge had little influence on the outcome of World War II. Instead of trying to settle this argument, my talk will examine the technical aspects of Sorge's work in Japan: I will describe the DIY radio station used to wirelessly transmit his dispatches over thousands of kilometers and show how these dispatches were manually encrypted using nothing but a pen, paper, and a book – suggesting that this method is still valid today, offering low-tech ways of concealing information, be it private or politically delicate material.

Talk ID
Saal G
9:45 p.m.
Ethics, Society & Politics
Type of
Anja Drephal
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