The US used "code talkers" in both world wars. Code talkers were Native Americans recruited to pass messages in their ancestral languages. The Germans became aware of code talkers during WWI and afterwards sent people to the US to learn the native languages. This proved to be difficult as there too many dialects to learn them all. During WWII, code talkers were used much more against the Japanese and less in Europe.

https://en.wikipedia.org/wiki/Code_talker