The Navajo Code Talkers, Part 1

Return to Course Outline

Previous Lecture

Anything You Want to Talk About?

(No.)

Navajo (and other Native American) Code-Talkers

The broad idea is to communicate secretly by using words from an obscure language as codes (i.e., replacements, but not literal translations) for words in a more widely understood language.

Motivation in U.S. Military Use

Many Native American languages are almost impossible for anyone not raised in them to understand.

This was used to good effect in World War 1, when the U.S. army used Native American languages to keep the Germans from understanding radio communication; this seems to have mostly involved radio operators speaking Choctaw (as a well-known example) rather than English, with limited actual code-talking (i.e., little use of Choctaw words or phrases to stand for anything other than their surface meaning to a Choctaw speaker).

Navajo in World War 2

When America entered World War 2, one Philip Johnston (White, but raised as a missionary’s son on the Navajo reservation) developed a much more sophisticated code-talking scheme based on the Navajo language.

Johnston proposed the general idea to the Marine Corps. When it was accepted, he worked with Navajo recruits to develop the actual code.

Key features of the code:

• A lexicon of common military words was encoded as Navajo words or phrases. For example, “bomber” was encoded as the Navajo word for “buzzard.” Originally around 200 words, growing by the end of the war to around 500.
• Words not in that lexicon were spelled out, using Navajo words to encrypt letters of the English alphabet. For example, “A” was encrypted as the Navajo word for “ant.” Originally one encryption for each letter, later up to 3 to reduce opportunities for frequency analysis.

It’s worth noting that this system is neither as unique as it might seem, nor as secure because of its uniqueness. While the United States has an advantage over many other countries of having a large number of indigenous languages it could use in such a system, it’s not the only place with lots of obscure (at least to the majors powers in World War 2) languages that are hard for non-native speakers to understand; for example many African languages would probably have been good starting points for such a scheme too. And obscurity of a language doesn’t mean you can rely on your enemies not knowing it. For example, one of the arguments for Navajo as the basis for Johnston’s code-talkers was that the Navajo were less studied by German anthropologists than many other American tribes, and the Japanese actually did know they were hearing Navajo on American radios, although they still couldn’t break the code.

This system was adopted by the Marines throughout the Pacific, and was wildly successful. It was faster than alternative mechanical/electronic coding devices. It was never broken by the Japanese, despite them knowing that they were hearing Navajo, and trying to use captured Navajo soldiers to decipher it.

Like most successful cryptography projects, the Navajo code was classified for years after the war; it started to become public in the late 1960s, and the surviving code-talkers were recognized for their work in the 1990s.

Try It

A declassified Navajo code-talker dictionary is available online at

https://www.history.navy.mil/research/library/online-reading-room/title-list-alphabetically/n/navajo-code-talker-dictionary.html

Try using it to encrypt and decrypt short messages (use the Navajo words, not their English translations, in your ciphertext). Then try deciphering someone else’s encrypted message(s).

Use a Google document to share ciphertexts:

Next

Discussion of experiences using the Navajo code, and analysis of it.

You’re welcome to keep experimenting with it in the Google doc. Also think about how easy or hard you find it to use and why, as well as how good a cryptosystem you think it is and why.

Next Lecture