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Museums 101: World War II cryptology (photo diary) [1]

['This Content Is Not Subject To Review Daily Kos Staff Prior To Publication.']

Date: 2023-07-17

The World War II Gallery in the National Museum of the United States Air Force in Dayton, Ohio includes an exhibit of cryptology.

According to the Museum:

Cryptology is the study of secret codes. Being able to read encoded German and Japanese military and diplomatic communications was vitally important for victory in World War II, and it helped shorten the war considerably. … In contrast to German and Japanese codes, American codes proved unbreakable due to a superior code machine known as SIGABA, the most secure cryptographic machine used by any nation in WWII.



The U.S. Army and Navy developed SIGABA before the war. "SIGABA" is not an acronym and does not stand for anything -- it is simply a code word. In 1935 Army cryptologists designed the basic machine, and they shared its design with the Navy. In 1940 the Army and Navy both adopted SIGABA, and the system became operational by August 1941. By 1943, more than 10,000 SIGABA machines were in use.



SIGABA machines linked with British machines to let Presidents Roosevelt and Truman communicate securely with British Prime Minister Winston Churchill. SIGABA was so secret, though, that British personnel were not allowed access to the machine.



The SIGABA system was used until 1959, when the speed of modern communications demanded new equipment. Most SIGABAs were destroyed to protect their design, and only a few exist today. The secret patent for SIGABA was declassified in 1996.

Shown below are the German Enigma and American SIGABA machines.

According to the Museum:

The Enigma and SIGABA machines on display have important similarities and differences. Both are "rotor machines," that is, they scrambled typed-in messages by sending electrical current through rotating wheels. Neither machine is a computer. They use electricity only to substitute letters in the alphabet with moving mechanical parts that are wired in a very complex fashion.



Neither machine can send or receive messages like a radio or computer -- they can only encipher or decipher typed-in text. Only another machine with exactly the same settings can decode a message. Both Enigma and SIGABA depended on a secret daily "keylist" of machine settings to keep enemy cryptologists from decoding messages.



The most important difference between the machines is in their complexity. Most Enigmas used three rotors and some used four; SIGABA used 15. This made SIGABA's letter scrambling much more complex, and practically unbreakable by cryptologists. Enigma is also older than SIGABA. Invented in Germany in 1918, Enigma at first was a commercial device to protect banking transactions. SIGABA was invented about 20 years later, and was exclusively military equipment.



SIGABA was easier to use than Enigma. The German machine needed two people to operate -- one typed in the message, and another copied down the resulting lighted letters. SIGABA, however, printed the letters on a paper tape, allowing a single person to operate it.



Both Axis and Allied forces had great faith in their code machines. With SIGABA, American confidence was justified. The Germans believed -- wrongly, it turned out -- that Enigma also was unbreakable.

More World War II museum exhibits

Air Force Museum: World War II flight jackets (photo diary)

Air Force Museum: World War II guns and bombs (photo diary)

Air Force Museum: World War II bomber crew protection (photo diary)

Air Force Museum: World War II memorabilia (photo diary)

Air Force Museum: World War II posters and historic photographs (photo diary)

Museum of Flight: World War II memorabilia (photo diary)

Veterans Memorial Museum: World War II (Photo Diary)

Veterans Memorial Museum: Women in World War II (Photo Diary)

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[1] Url: https://www.dailykos.com/stories/2023/7/17/2181424/-Museums-101-World-War-II-cryptology-photo-diary

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