CX-52 cipher machine from Crypto AG.
Swiss National Museum

The CX-52 cipher machine and an espionage scandal

The CX-52 is one of the first cipher machines produced in Switzerland by the company Crypto AG. It is a much sought-after collector’s item and symbolises the greatest espionage scandal since World War II.

The device has a harmless appearance, rather like a cash register: you set the letter you want to encrypt by means of a dial, operate a lever on the right-hand side and then read off the encrypted letter from the outer edge of the disk. The encryption is regulated with the six wheels visible on the front of the device. The CX-52 was one of the first devices that the Swede Boris Hagelin and his Swiss company Crypto AG put on the market in 1952. When operated correctly, it was completely secure. Hagelin later produced other versions of the device that were easy to crack.

Today, the story of Boris Hagelin and his company Crypto AG reads like a spy thriller:  Boris Hagelin (1892-1983), born in Russia, was an electrical engineer, who in 1922 joined the Swedish company AB Cryptograph, which at that time belonged to the Nobel family. He was soon in a position to take over the company, running it under the name AB Cryptoteknik. He developed a range of cipher machines, one of which he sold to the US Army in World War II. The US Army produced more than 140,000 of them under the name M-209. After the war, Sweden placed restrictions on the export of cipher machines because they were viewed as armaments. Boris Hagelin therefore moved to Switzerland and founded Crypto AG in 1952.

Boris Hagelin’s business had brought him very good contacts in the United States, in particular with the legendary cryptologist William F. Friedman (1891-1969), who also originally came from Russia and who later headed the cryptography department of the American secret service, the National Security Agency (NSA). In 2015, the NSA released thousands of Friedman’s papers, 400 of which relate to Boris Hagelin and Crypto AG. Today we know that: Friedman and Hagelin agreed on extensive cooperation as far back as the early 1950s and exchanged information regularly.

Boris Hagelin ca. 1940.
Wikimedia

The CX-52 at the National Museum Zurich

The Swiss National Museum collects cultural assets of importance for the history of Switzerland. Among these is a Crypto AG cipher machine from 1952 that we acquired recently. The device symbolises the scandal surrounding the Zug-based company, which created an uproar in mid-February 2020 under the hashtag #Cryptoleaks. The cipher machine will be on display in the National Museum foyer from 29 February.

At first, the NSA did not reap many rewards from the CX-52: it was difficult to crack. However, they soon found a way around the problem: if the CX-52 was not operated properly, it was easy prey for the secret service. This is why the NSA produced ‘alternative’ manuals for Crypto AG. In later production series, Crypto AG made different versions of the machine, secure and less secure. The secure ones went to the NATO countries and Switzerland, while all other countries received less secure machines. From then on, the American secret service had a say in all developments at Crypto AG.

CX-52 cipher machine from Crypto AG.
Swiss National Museum

Boris Hagelin sold his company in 1970. The German Federal Intelligence Service and the CIA took over Crypto AG through a cover company. As early as the 1970s, some Crypto employees became suspicious. In one case, the Swiss federal prosecutor even conducted an investigation – although no conclusion was reached. In 1992, sales engineer Hans Bühler was arrested in Tehran on charges of spying. He was in prison for nine months. On his return, Crypto AG dismissed him. Bühler then revealed through the media the real reason for his arrest: the Iranians suspected that the Crypto devices had a back door for US intelligence. Although the suspicion could not be proved, it was never completely quashed. In February 2020, a secret service document came to light that described in detail the events surrounding Crypto AG and confirmed what had been suspected: the German Federal Intelligence Service and the CIA had been involved in a joint operation which enabled them to read encrypted messages from over 130 countries.

SRF DOK on the #Cryptoleaks revelations (in German).
YouTube/SRF

Many questions still need answers: What did the Swiss authorities know? How will the scandal affect Switzerland’s neutrality? Who leaked the secret papers to the media and why? What was the historical importance of this operation?

The company Crypto AG was sold in 2018 and has since been run as two independent companies that have no links with the old Crypto AG.

Declassified NSA documents concerning Boris Hagelin’s correspondence are available on the NSA website.

Simulation of the CX-52 by the Belgian cryptologist Dirk Rijmenants. It can be downloaded as software and also contains a detailed description of how the device works.

Dominik Landwehr
Dominik Landwehr is a cultural and media scientist and lives in Winterthur.

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