United States Coast Guard Unit 387

The United States Coast Guard Unit 387 (short: USCG Unit 387 ; German  about " Group  387 of the Coast Guard of the United States " ) was the cryptanalysis unit of the American Coast Guard . One of their most important achievements is the breaking of intercepted secret radio messages , code name Green ( German  "Grün" ), with which the German Abwehr ( intelligence service of the Wehrmacht ) controlled their worldwide espionage network during the Second World War , and with the help of the rotor cipher machine Enigma-G had been encrypted .

history

Elizebeth Friedman (1892–1980)

The Enigma-G (with four rotating rollers) was the German key machine used mainly for secret service purposes

The unit had its beginnings well before the Second World War, in the 1920s, at the time of Prohibition in the United States . At that time, criminal smuggling gangs operated a wide-ranging transport network for illegal alcohol ( rum running ), which also included a whole fleet of smugglers. Mainly from Cuba , the spirits were shipped to Florida via the so-called Rum Row ( German  "Rumweg" or "Schnapsstraße" ) . In order to prevent the coast guard from picking up the ships, they were directed by the smugglers using encrypted radio messages. The US Treasury Department countered this by creating a special cryptanalysis group, the head of which was the American cryptanalyst Elizebeth Friedman (picture) . She managed to decipher more than 12,000 of the radio messages . This enabled many illegal smuggling operations to be uncovered and the people behind them identified and convicted. Even entire contraband rings, like the Consolidated Exporters Company , could be blown up in this way.  

In 1931, shortly before prohibition was lifted in 1933, the unit was officially subordinated to the Coast Guard as USCG Unit 387 and thus to the United States Department of Defense and to the Federal Bureau of Investigation (FBI) , to which it will now report directly would have. It continued to intercept and decipher suspicious radio traffic during the 1930s. Not only were all kinds of smuggling operations uncovered, but secret exchanges of messages between the Axis powers and their agents, mainly in Central and South America, were observed.

The experience and potential of the unit after the entry of the United States into World War II became of particular importance . This enabled the Coast Guard Unit 387 in 1942 American than the first group ever to break three special Enigma-G networks. This included the so-called Green Enigma Code , a special key network of the German defense. As the war progressed, more than 10,000 enemy radio messages were deciphered, making a significant contribution to the American war effort .

literature

• Philip Marks: Enigma Wiring Data - Interpreting Allied Conventions from World War II, Cryptologia , 39: 1, 2015, pp. 25–65, doi: 10.1080 / 01611194.2014.915263
• G. Stuart Smith: Elizebeth Friedman's Security and Career Concerns Prior to World War II, Cryptologia, 2017. doi: 10.1080 / 01611194.2016.1257523

Web links

• History Of Coast Guard Unit 387 , accessed December 28, 2018.

Individual evidence

1. ↑ Friedrich L. Bauer: Deciphered secrets. Methods and maxims of cryptology. 3rd, revised and expanded edition. Springer, Berlin a. a. 2000, p. 257.
2. ↑ Cyber ​​Strategy PDF 4.1 MB p. 7
3. ↑ The Cutter - The Newsletter of the Foundation for Coast Guard History, 2009. PDF 2.2 MB p. 5