Enigma Machines & Encryption Devices That Hid the Secrets of WWII

WWII was full of secrets that the Axis and Allies desperately wanted to keep. Discover the mechanical encryption machines that kept them.

Published August 12, 2023
3-rotor Wehrmacht Enigma machine in wooden box used during World War Two

What could Germany's famed Enigma machine and the Zodiac Killer possibly have in common? Everyone thought their codes couldn't be cracked—until they were. World War II's secret battlefield wasn't some Central European location. It was fought on tiny typewriter-like machines. Intelligence was the name of the game, and whichever country had the better encryption was sure to win the war.

Thanks to The Imitation Game, Enigma machines have been dusted off and thrust into the spotlight. And while their history is fascinating, there are so many other cipher machines from WWII to explore.

How Germany's Enigma Machine Almost Cost the Allies the War

During war, the last thing you want is for your enemy to get access to troop movements, armament locations, and battle plans. But, like keeping gossip a secret in middle school, juicy information draws people in like vultures.

Instead of writing about their crush in their diaries, both Allied and Axis powers used more mechanical ways of protecting their secrets during WWII. Encryption machines took written documents and encoded them so that only people with those specific devices could decipher the code.

Germany's Enigma machine is the most famous of these from the period, due in large part to the monumental efforts of intellectuals at Bletchley Park to crack the supposed 'unbreakable' code. What's more memorable is the fact that the world didn't discover the British had decrypted Germany's machine until a 1974 book, The Ultra Secret by RAF Intelligence Officer Frederick Winterbotham, was published.

How Did the Enigma Machine Work?

Being complicated seems like a prerequisite for any encryption machine, and Enigma is no exception. While there are definitely a lot of mathematics involved, the basic premise of Enigma is that there was a typewriter-like box that you could press a key down representing a letter of the alphabet, and a different letter would light up, giving you a code for each letter in your message.

To read one of these encrypted messages, you'd need a codebook that gave you the machine's unique settings for each day of the year and an Enigma machine. Given the internal mechanisms that could be reset into different configurations, there are approximately 150 quintillion possible combinations. You can see why unbreakable was the word of choice.

Can You Buy an Enigma Machine Today?

Since Enigma machines were a field device that military personnel needed to communicate with one another across vast spaces, the Germans made a great deal of these machines before the war ended. However, they're pretty hard to come by. If you're lucky enough to find one, you're looking at prices in the $150,000-$500,000 range or more.

For example, a four-rotor Enigma machine from 1944 sold in a Christie's auction for $547,500 in 2017. Enigma machines are by far the most popular encryption device from the war, making them super collectible and worth a ton of money.

4 WWII Encryption Machines You've Never Heard Of

The Enigma machine wasn't the only encryption device used in WWII. Practically every large-scale operation in the war had their own version of the Enigma, some of which you can still find today.

Typex Machine

In 1934, the  British invented the Typex machine. Just like Enigma, Typex (or Type X as it's sometimes written) used a rotary system to help encode their messages. Naturally, they made adjustments throughout the war and ended up with at least nine different variant designs.


The SIGABA was the American response to Enigma, and reportedly the only encryption system that wasn't cracked during the war. It, too, worked on a rotary-based system, though the possible combinations were much higher. Because of its bulky, heavy design, it wasn't as effective of a field unit as other encryption machines and largely stayed out of the front lines.

Japanese Purple Cipher Machine

Japan also had their own encryption machine, 97-shiki O-bun In-ji-ki, nicknamed Purple by the United States. Much like Enigma, Purple used a typewriter-like rotary-based system to create its encryptions. But, instead of spitting out codes from the same device, it was hooked up to a typewriter that would type out the encoded text for you. And while it was an impressive advancement to Enigma—which needed two people to operate—it wasn't unbreakable, with the U.S. breaking it only a few years after its creation.


K-37 was the Soviet encryption machine that popped up a little later than the others, circa 1940. Just based on looks alone, you might think a K-37 was actually an Enigma, but the encryption method was slightly different. Yet, in 1946, the United States cracked its code, leading the Soviets to abandon the project.

Can You Keep a Secret?

Let's face it, humans love gadgets, and World War II was chock-full of 'em. The Enigma machine and other encryption devices scratch that itch for espionage and intrigue, so of course any remaining machines that haven't already been snatched up by museums and archives would be super valuable.

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Enigma Machines & Encryption Devices That Hid the Secrets of WWII