In the context of computing, it's interesting to note that codebreaking was actually one of the major purposes of supercomputers initially, to break DES and other weak encryptions (decades after World War II concluded).
Enigma machines however, were not computers. There is electricity, a keyboard (German QWERTZ layout), lamps that illuminate to communicate information, and it is a machine that automates a useful task, but the similarities end there. There is no binary encoding nor even a single relay.
It is more accurate to depict Enigma machines as a complicated series of switches than to consider it a type of computer. The physical act of pressing a key bridges an electrical connection through a complicated route (and automatically advances its rotors), eventually illuminating an output lamp corresponding to a single letter.
See the diagram of its operation to the right, which is one of the many plaques in the Enigma Machine miniature-museum nook.
Various models of (incompatible) Enigma machines were used in various branches of Nazi Germany's armed forces. You may read an overview of the various models at Wikipedia. Because these models are incompatible for enciphering and deciphering messages from each other, it is important to note which Enigma machine is displayed at the Computer Museum of America.
The Enigma machine at Computer Museum of America is a three-rotor M3 model delivered to the Wehrmacht Heer (Army of Nazi Germany) in Berlin, on 7 March 1936.Per September 9 2020 CMoA News Release We know the date of delivery because the machine notably still retains its original delivery papers.
To its right, there are two additional rotors placed on top of their rotor box. These were generally supplied as an update to the Army's Enigma machine in December 1938.Kruh, L.; Deavours, C. (2002). "The Commercial Enigma: Beginnings of Machine Cryptography". Cryptologia. 26: 1–16. doi:10.1080/0161-110291890731. S2CID 41446859. Three of the five total rotors could be chosen at a time to encipher and decipher messages, adding to the complexity of code cracking. Read more at Wikipedia - Enigma rotor details.
To the left of the Enigma machine is a WWII era "Baumuster T1" Morse Key, with the text "vor dem Öffnen Stecker herausziehen" embossed, which translates to "unplug before opening". This would not have been used as an input device with the Enigma machine (despite the plug looking similar and being placed next to it), but instead is included in the display apparently to highlight that messages enciphered with the Enigma machine were typically transmitted via morse code.
Morse code is a prominent secondary theme of the exhibit. There is a worksheet for children on field trips to decode Morse and decipher a brief Enigma encoded message. Additionally, the plaques on the very left of the exhibit discuss a history of the emergence of morse code, relate it to the earlier Zimmermann telegram, and conclude that "Morse Code + Radio Transmission + Enigma" "gave the Axis powers a seemingly unbeatable advantage: centralized battle planning combined with instant—and secret—communication with field commanders."
Since we are on the topic, Morse code is not considered a binary method of data transmission, since time gaps are part of the protocol. It is trinary: dits, dahs, and gaps. One of the first usages of computers in the hobbyist community was to automatically send and decode morse code in HAM radio, as advertised for the 1974 SCELBI-8H.
Breaking Enigma
Main article: Wikipedia - Cryptanalysis of the Enigma
This is a very large topic, leading from the fact that it was a very large effort conducted by many separate teams of dozens (sometimes hundreds) of people, across multiple years, in multiple countries. Also complicated by the fact that "The Enigma Machine" was not a single machine, but at least 7 different models which were (in some cases) separately cracked.
Computer Museum of America gave this short summary in their September 2020 News Release:
Early during World War I, the Allies broke coded messages with increasing regularity, so it was paramount to the Germans to drastically improve their encryption capabilities. As World War I was concluding, German engineer Arthur Scherbius invented the Enigma, the world’s first electromechanical encryption device. It was used to encode and decode secret messages for commercial and governmental bodies of several nations, including Germany's Nazi party during World War II. It was believed to be unbreakable at the time, until Turing and his team at Bletchley Park cracked the code. Some experts believe this incredible feat shortened World War II by as much as two years.
The actual exhibit goes into more details (this is by-far the most detailed exhibit at CMoA), additionally crediting:
- Initial Polish codebreakers Marion Rejewski, Jerzy Rozycki, and Henryk Zygalski
- British Bletchley Park collaborators:
- Alfred Dillwyn Knox, major organizer, helped negotiate transfer of Polish work to British team
- Women of Bletchly Park, and the Colossus Mark 2 computer (which was inspired by Turing's Banburismus)
- Joan Murray, "close friend" of Alan Turing, cryptanalyst at Bletchley Park
- Mavis Lilian Batey, broke the Enigma model G at Bletchley Park
- Stuart Milner‑Barry, "one of four leading code breakers at Bletchley Park to petition Churchill directly for more resources"
- Gordon Welchman, "one of the most important contributors" at Bletchley Park
- Hugh Alexander, "considerably improved" Turing's Banburismus
- Margaret Alice Rock, "4th or 5th best of the whole Enigma staff" per Alfred Dillwyn Knox
- Jane Fawcett, decoded a message that helped sink a battleship
- More than 100 veterans who reunited at Bletchley Park in 2017.
- British sailors involved in recovering the naval Enigma machine from German submarine U-110 in May 1941
- David Balme
- William Stewart Pollock
- Bill Roper
- American contributions:
- Signal Intelligence Service, precursor of the National Security Agency (NSA)
- William Friedman, director of SIS
- Elizebeth Smith Friedman, "America's first female cryptanalyst"
- Joseph Desch, who was contracted by the National Defense Research Committee to build the US Navy Bombe, while working at NCR.
Undoubtedly, if there is just one name to remember, it's Alan Turing. He led the team at Bletchley Park, developed the primary method of breaking Enigma codes (Turingery), and generally is recognised as a massive contributor to the fields of mathematics and early computing. It is his picture on the wall seen immediately upon entering the museum. See also Wikipedia - Legacy of Alan Turing and Wikipedia - List of things named after Alan Turing.
Important Media
Please view the above 5 minute video (local mirror, 198MiB) of Lonnie Mimms talking about the Enigma Machine on September 19th, 2020. Lonnie tells interesting stories of design flaws that contributed to the cipher being cracked, as well as the story of how CMoA came into possession of their Enigma machine.
This video was filmed by David Larsen: major donor of artifacts in the CMoA collection, founder of the previous Bugbook Historical Microcomputer Museum, and board member of CMoA.
Larsen wrote in the video description on YouTube:
This video was made during the first showing of the Enigma Machine 9/19/2020. Lonnie Mimms founder of the museum is the story teller for the video and he really knows his computer history. The Enigma machine at CMoA is a 3 rotor model in near perfect condition. It was purchased on March 7, 1936 by the German army according to the original papers from the company which produced the Enigma. [...] I visited the "Computer Museum of America" in Roswell, Georgia for the first showing of the Enigma Machine 9/19/2020. The Machine was acquired by the museum's founder Lonnie Mimms earlier this year and is a very special addition to the historical items in the archives.
Warning: Loud clipping audio. Forgive the 2008 video quality.
Another informative video,(local mirror, 6MiB) the NSA did a live demonstration of the use of a three-rotor Enigma machine (like the one at CMoA) in 2008. The demonstration shows that from a beginning position, the cipher is a 1-to-1 mapping between letters (like a more primitive Caesar cipher, but changing on each successive letter).
The NSA has several Enigma machines of all different models on display at the National Cryptologic Museum in Maryland.
Image Gallery
See this open directory for a gallery of Enigma images.
Instructions and their English Translation
Instructions on how to operate and maintain the machine are printed on a plaque screwed to the top lid. On the bottom flap (towards the front of the machine), it says "Klappe schliessen", which means "Close Flap" in English. It is explained in the instructions that this is to keep the plugs from falling out.
I produced the following transcription and translation using 2024 Google Translate (too polite, but good reference), ChatGPT 4o (Large Language Models are quite good at translation, but sometimes reword and substitute nonfaithfully, especially in long texts), and my own knowledge of German (three years study of modern German, quite a while ago).