Enigma cipher machine

Made by Chiffriermaschinen AG in Germany, 1919-1945.

This is an encryption device commonly referred to as an Enigma. The Enigma was a rotor-based code machine used by various branches of the German military before, during and after World War II. It was used to encipher messages and decipher messages. Enciphering means converting messages from plain text to code by substituting letters in such a way that only a person with the solution or key to the code could read them. Deciphering or decoding messages means converting them from code to plain text...

Summary

Object No.

94/90/1

Physical Description

Wehrmacht (German army) type cipher machine in oak carry case. The top of the machine consists of three rotors, a Bakelite switch with two options, a lettered lamp board, and a keyboard in the following configuration: QWERTZUIO on the top row, ASDFGHJK on the middle, and PYXCVBNML on the bottom. The keys are made of metal and black Bakelite with white letters.

A lettered lamp board is positioned above the keyboard. It is encased in a beige metal casing, which can be lifted by unscrewing two round nuts located to either side of the device. Pulling the casing up reveals three rows of lamps to light the letters, the three numbered rotors, and switching gear.

The front panel of the carrying case opens forward to display a plug board. The plug board consists of twenty-six sockets, each representing a letter, and ten cables to plug into the sockets and make the connections.

The carry case has a hinged lid and fall front. It is secured by way of two small metal hooks on the sides of the case, and a metal fold-in handle. Inside the lid is a white Bakelite label with German text printed in black, two spare plug cables, three spare bulbs for the lamp board, and a strip of black Bakelite screwed onto the lid.

Dimensions

Height

155 mm

Width

280 mm

Weight

9 kg

Production

Notes

The Enigma machine was originally designed by German engineer Arthur Scherbius. He developed Enigma in 1915, about the same time others were developing similar rotor-based code machines around the world. For example, two Dutch naval officers, Theo A van Hengel and PRC Sprengler, had devised a rotor-based machine that was similar to Enigma. Scherbius applied for his patent on 23 February 1918.

Scherbius, after initially failing to convince the German military of Enigma’s ciphering potential, established the Chiffriermaschinen Aktiengesellschaft (Cipher Machine Stock Company) in 1923. The company produced commercial versions of the machine that were sold to businesses. During this time Enigma, originally over 100 pounds (about 45kg), was streamlined into a device that was no bigger than a portable typewriter.

Enigma cannot transmit or receive messages on its own. It may only be used to encipher and decipher messages, or convert plain text to and from code. The most basic type of code substitutes a word, letter or symbol for another word. Enigma was different in that the code it produced was much more complex, as each letter was substituted for another letter. Depressing the key for a given letter causes a signal for that letter to pass through the three rotors and the plug board. This operation causes a cascade of substitutions for the original letter. In this manner, a message can be encoded so that it can only be decoded by playing back through the same sequence of substitutions. The operator doing the decryption would have to know the specific key settings to decipher any incoming messages.

A team of two was used to code and decode messages. The operator would type the message, limited to 250 words, into the machine. The machine would substitute letters and relay the code, one letter at a time, on its lamp board. The operator’s assistant would record the code for the radio operator to transmit. The keys, which dictated the configuration and placement settings of the rotors and the plug board, could be changed daily. The key for a given day was relayed in the code book; there were up to 159 million million million (159,000,000,000,000,000,000) possible keys.

The device was intended to prevent the repetition of a sequence of letters, even if the same letter is struck multiple times. Each rotor is covered with 26 electrical contact points that connect randomly to similar contacts on the other side of the rotor. Each contact point represented a letter. The rotor turned 1/26th rotation with each keystroke to the keyboard, so that each subsequent letter would always be different. Once the first rotor had gone through an entire cycle, the second rotor would be engaged; it would turn 1/26th with each complete rotation of the first rotor. The third rotor would likewise only move when the second had completed a rotation.

The German Navy (Kriegsmarine) adopted the Enigma machine to encrypt their communications in 1925 and implemented a number of modifications. In 1928, the German Army (Wehrmacht) followed in the Navy’s footsteps and adopted the Enigma machine. The Wehrmacht also modified its machines, adding a plug board (Steckerbrett) to the base of the device. The plug board consisted of 26 sockets, representing letters, which were connected to both the keyboard and the lamp board. This plug board swapped letters before they entered the rotors and again after they exited them, effectively increasing the size of the mathematical variables for the encoded letter.

These modifications lulled the German authorities into thinking that the Enigma was unbreakable, and they used it until the end of the war. Various versions of Enigma were also adopted by the German Air Force (Luftwaffe), the railway service, the Abwehr and the SS. It was continually modified and updated throughout the war, usually with the addition of more rotors to increase encryption.

Made

Chiffriermaschinen AG 1919-1945

Designed

Scherbius, Arthur 1915

History

Notes

German high command had faith until the end of the war that Enigma was untouchable. However, the basic code had been broken by the Polish Biuro Szyfrow in 1932, with the help of a commercial Enigma machine and code books and manuals provided by the French. The French bought the documents from Hans Thilo Schmidt, who worked in the German Defence Ministry. Three Polish mathematics students, Jerzy Rozycki, Henryk Zygalski and Marian Rejewski, invented a machine they called a Bomba (different from Bletchley Park’s Bombe) to identify repetitive letters.

In the 1930s, each encrypted message began with three letters that relayed the message setting; to reduce mistakes, the Germans repeated the three letters so there was a six letter cipher at the beginning of each message. The Poles analysed the message-settings with the Bomba and compared the first set of letters against the second, which let them break the code. As a result, the Poles could read about 75% of Enigma-encrypted messages by the early 1930s.

The Germans continually modified Enigma, however, and the addition of two more rotors in 1938 ended the ability of the Poles to decipher messages. In July 1939, just before the invasion of Poland by Germany, the Polish code breakers met with the British and French and passed on all the information they had amassed on Enigma, including clones of an Enigma machine with plug boards.

With this information, the British began working on the code at the Government Code and Cipher School at Bletchley Park. In April 1940, a team including Dilly Knox, John Jeffreys, Peter Twinn and Alan Turing broke the Luftwaffe and Wehrmacht operational ciphers for the first time. It would be an ongoing effort throughout the war, as the code had to be broken anew each day.

Aided by a captured Enigma machine and code books, Bletchley Park was decoding and reading over 4,000 Enigma-encrypted messages per day by 1942. The Y Service, a chain of radio intercept stations around the UK and Europe, intercepted German messages, which would then be sent to Bletchley Park. There, the cryptographers used the Bombes to identify pieces of text called cribs to break the ciphers. Cribs were words the cryptanalysts guessed to be in the message because German military communications often included specific phrases. For example, many messages included the words "Heil, Hitler" or a weather report, which was the crib used to break the code on D-Day. The crib would help analysts and the Bombes preclude certain rotor settings.

The Bombes would cycle through the potential rotor settings to reduce the number of settings that could be possibly used. What remained would then be deciphered by hand. Others at Bletchley Park would decipher the actual messages once the settings were discovered. The decrypted messages were then passed on to special liaison units to decide what intelligence (code named ULTRA) was useful and could be used. The Allies could not use everything gathered from the broken codes, as they risked alerting the Germans to the fact that the Enigma code had been broken. Nevertheless, decoded Enigma messages provided crucial tactical information in Europe and the North African campaigns.

After the end of the war in 1945, most Enigma machines were believed to have been destroyed. Still others were taken by the Allies, though several countries continued to use it as their principal cipher machine, including Norway, Germany and Austria. Versions of Enigma were refined and modified by the Americans and Russians, which provided the basis for the more sophisticated Cold War-era rotor-based cipher machines M-125 (Fialka) and KL-7 (ADONIS and POLLUX).

Enigma machines were quite rare until the end of the Cold War, when the fall of the Berlin Wall revealed that many had survived in Eastern Europe.

References:
Colossus: The Secrets of Bletchley Park's Code-breaking Computers, ed. B. Jack Copeland
Code-breakers: the inside story of Bletchley Park, ed. F.H Hinsley and Alan Stripp
Alan Turing, Andrew Hodges
Enigma: The Battle for the Code, Hugh Sebag-Montefiore
www.bletchleypark.org.uk
http://www.iwm.org.uk/history/how-alan-turing-cracked-the-enigma-code
http://enigmaco.de/enigma/enigma.html

Source

Credit Line

Purchased 1994

Acquisition Date

29 April, 1994

Cite this Object

Harvard

Enigma cipher machine 2017, Museum of Applied Arts & Sciences, accessed 21 January 2018, <https://ma.as/141921>

Wikipedia

{{cite web |url=https://ma.as/141921 |title=Enigma cipher machine |author=Museum of Applied Arts & Sciences |access-date=21 January 2018 |publisher=Museum of Applied Arts & Sciences, Australia}}
This object is currently on display in Icons: From the MAAS Collection at the Powerhouse Museum.

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