"The Navajo code is the only spoken military code never to have been deciphered."
First, damn. Second, never let it be forgotten this achievement was the product of the code talkers' own ingenuity and cooperation--they created the initial code, and they met to update it in response to the demands of field use. Navajo creativity and resourcefulness, based on their heritage that settlers attempted to annihilate, beat the difficult problem of tactical speed cryptography, decoding in 20 seconds messages the machines at the time took 30 minutes to process. The Navajo code books were never taken into the field (that was how the Nazis' Enigma code books were captured, during battle); the code talkers kept everything in memory, and they beat the latest computing technology and the advances of the Japanese Empire's cryptography. If that's not punk as fuck idk what is.
Edit: It seems that other Native spoken codes such as the Comanche one were also never cracked, see The Comanche Code Talkers of World War II by William C. Meadows.