Enigma machine

The Enigma machine is a special device made to hide messages in the early to mid-1900s. It was used by Nazi Germany during World War II to keep secret messages safe for the German military. People thought it was very hard to read these hidden messages.

Military Model Enigma I, in use from 1930

The Enigma machine works with parts called rotors that mix up letters. When someone types a letter on the keyboard, a different letter lights up, making it look like a secret code. Each press of a key changes the mixing, so every letter is hidden in its own special way.

Even though it seemed very safe, experts in Poland figured out how to read these messages as early as 1932. This helped the Allies learn important secrets during the war. Even when Germany changed the machine, people kept finding ways to read the messages, which helped shorten the war.

History

The Enigma machine was invented by a German engineer named Arthur Scherbius after World War I. His company started selling these machines in 1923, mostly for businesses. Later, several countries, including Nazi Germany, used Enigma to keep their military and government messages secret during World War II.

A memorial in Bydgoszcz, Poland, to Marian Rejewski, the mathematician who, in 1932, first broke Enigma and, in July 1939, helped educate the French and British about Polish methods of Enigma decryption

Germany needed safe ways to send messages during the war. The Enigma machine was small and easy to carry, which helped protect these messages. Allies worked to understand how Enigma worked. Polish experts were the first to learn some of Enigma’s secrets. They shared this knowledge with British and French intelligence before the war. This early work helped British codebreakers at Bletchley Park as they continued to study Enigma messages.

Main article: Cryptanalysis of the Enigma

Design

The Enigma machine was a clever device used to hide messages during World War II. It looked like a keyboard with lamps underneath and used spinning parts called rotors to change each letter into a secret code. When someone pressed a key, the rotors turned and changed the letter into a different one, making it very hard to guess.

The machine worked by sending an electric current from the keyboard through the rotors. Each rotor had wires inside that mixed up the letters, creating a complex code. There was also a part called a plugboard that let people swap pairs of letters before the signal went through the rotors. This made the code even harder to break. The Enigma was used by parts of the German military to keep their messages safe.

Position of turnover notches
Rotor	Turnover position(s)	BP mnemonic
I	R	Royal
II	F	Flags
III	W	Wave
IV	K	Kings
V	A	Above
VI, VII and VIII	A and N

Operation

German Kenngruppenheft (a U-boat codebook with grouped key codes)

The Enigma machine was a special tool used to send secret messages during World War II. It worked by changing each letter someone typed into a different letter. This made the message hard to read for anyone who didn’t have the same machine.

When someone used the Enigma, they pressed keys on the keyboard. Lights would show different letters, which another person would write down. Each time a key was pressed, the machine’s parts moved. This made the next letter change to a new letter. This made the message very hard to understand unless someone had the exact same machine settings.

Models

Scherbius Enigma patent, U.S. patent 1,657,411, granted in 1928

The Enigma machine was a special tool used to send secret messages. It changed ordinary letters into a secret code. It was created in the early 1920s and used by many countries for important messages. About 40,000 of these machines were made.

Early versions were used for business. Later, the German military used it for secret messages during World War II. The machine had parts called rotors that moved to change the letters. This made it very hard to read the messages without the right machine. Different models were made over time, each with small changes to improve how it worked. Some models were used by armies, while others were used by navy or air force groups.

Surviving machines

People became very interested in the Enigma machine after learning how its secret code was broken in 1973. Today, you can see Enigma machines in museums and private collections all around the world.

The Deutsches Museum in Munich and the Deutsches Spionagemuseum in Berlin both show examples. You can also find them at the National Codes Centre at Bletchley Park, the Science Museum in London, the Australian War Memorial in Canberra, and the Computer History Museum in Mountain View, California. At many of these places, visitors can try encoding and decoding messages themselves.

Enigma machines have turned up in unexpected spots. In 2020, a damaged machine was found in the Baltic Sea near Flensburg Firth and is being fixed up. In 2025, an Enigma used by a well-known World War II leader sold for over 480,000 euros at an auction in Paris.

Derivatives

The Enigma machine inspired many other cipher machines. After learning how Enigma worked, the British made a similar machine called the Typex.

In the United States, William Friedman created a machine called the M-325 that worked in a similar way.

Other machines like the SIGABA and NEMA were different enough that they are not considered true Enigma copies.

In 2002, a person in the Netherlands named Tatjana van Vark built a special machine that could handle letters, numbers, and some symbols. There were also copies made in Japan and electronic versions sold as souvenirs.

Simulators

Main article: List of Enigma machine simulators

There are many tools and programs that let you try out how the Enigma machine worked. These simulators help us learn about old secret codes and how people tried to keep messages safe. You can use these tools to see how hard it was to break the Enigma machine's codes.