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In reading about this topic recently, to my understanding, the encryption schemes used on top of the Navajo language were very simple and definitely could have been broken (my research shows they mapped Navajo words to various different meanings).

The Navajo language alone is obscure, had few speakers, and was not a written language - but still I'm amazed that the code was never broken. Isn't this an example of "Security through obscurity"?

No matter how obscure the language was, the sounds still mapped to English phrases at the end of the day. Through cryptanalysis, shouldn't the Japanese have broken the code? Am I missing something here, or is this an example of security through obscurity actually working?

Edit: Follow up question: Could a similar scheme work today?

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    $\begingroup$ No time for decent answer, but here’s a hint: Imagine you’re a Japanese cryptanalyst in 1944. No TV or wordwide network feeding you with knowledge et al. In that case there’s only a minimal chance you’ve ever heard or seen a Navajo. So, you’ll be wondering what Joe is talking about as it sure doesn’t sound like English. Is that a failed decryption attempt? What’s the char frequency of Navajo? And since it’s a descriptive language: how would you know what is meant by (eg) “wolf feeds bisons when eagle moon embraces cloud rock”? Think “security through obscurity”; better: “living codebooks”. $\endgroup$ – e-sushi Feb 4 '16 at 19:30
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    $\begingroup$ It's just a matter of time and resources. Think for example how researchers have "decoded" the ancient Mayan hieroglyphs. I wouldn't say that the Navajo code is an example of "security through obscurity" actually working, but rather "security through obscurity" buying some time. In the middle of the war, it's far easier to take a bunch of Navajo speakers than design a secure coding, train people, etc. But in the end, the task of breaking the code is still a matter of time and resources. $\endgroup$ – cygnusv Feb 5 '16 at 7:08
  • $\begingroup$ BTW, there are examples in the WWII of the reverse case. See for example this answer. There is no reason why the Japanese could not have followed the same approach to "break" the Navajo code $\endgroup$ – cygnusv Feb 5 '16 at 7:11
  • $\begingroup$ I think that in a completely unknown language you have to do frequency analysis on whole words and match that against English. I believe they just didn't have the word-level stats for English, in the military context, and I guess they did not have enough material to derive any significant stats from. $\endgroup$ – user31203 Feb 5 '16 at 15:09
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    $\begingroup$ @MichaelGoldstein Well, there aren’t many Navajos living today (last I heard was something in the thousands), so I’ld say that an on-point answer to your comment strongly depends on the exact scenario. But looking at the means available today, I tend to say that – in contrast to the WW2 – they indeed wouldn’t be very helpfull in terms of security in most situations. It’s like using the Klingon language from Star Trek, or Elvish from Lord of the Rings… as long as only a few know it, it might add a minimal bit of security. But nowadays, you can even take online courses to learn Klingon etc. ;) $\endgroup$ – e-sushi Feb 5 '16 at 19:20
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Wrapping up my comment as an answer:

Imagine you’re a Japanese cryptanalyst in the year 1944. There is no such thing yet called “television”, and you’re still decades away from a wordwide network feeding you with all the knowledge you could wish for.

In that case there’s only a minimal chance you’ve ever heard or seen a Navajo. So, you’ll be wondering what “Joe” is talking about as it sure doesn’t sound like English. You‘ll be asking yourself things like: Is that the plaintext in some language I don’t recognize or simply a failed decryption attempt?

Furthermore, even if you would know it is Navajo and assuming you would have some plaintexts to your availability, you would still be wondering about the more simple things of cryptanalysis, like: What’s the character frequency of Navajo anyway?

Even more, since Navajo is a descriptive language. Even having things like character frequencies and plaintexts at hand, how would you know what is meant by (eg) “wolf feeds bisons when eagle moon embraces cloud rock”?

See, Navajo indians may know “cloud rock” from stories told by their elders and they may know the exact day in the year when the “eagle moon embraces“ it… but you – sitting in your cryptanalysis room in Japan – have a rather minimal chance of even grasping half of it.

All in all, the use of Navajo boils down to a suplemental layer of “security through obscurity”. Maybe it helps if you think of the Navajo communicators as “living codebooks”. Embedding them (especially in key positions) added an additional layer of security to the already used cryptographic protection during radio communication et al.

In fact, take the actively used (radio) encryption during WW2 and add a layer of Navajo language use on top of it, and you’ll end up with something that could almost be called “double encryption”.

edit

To answer the additional question from your comment (now follow-up question added as an edit)…

I think both of these are good explanations of why this scheme worked. From your explanations it seems to me the primary reason it wasn't broken is because it happened 70 years ago. Am I correct in saying this would never work today?

Under most conditions – Yes, that’s correct.

Of course, this depends on the exact situation. The reason I’m saying that is that there aren’t many Navajos living today (last I heard was something in the thousands). Some specific scenarios might change that “yes” to a “no”. But generally, looking at the means (and resources) available today, I tend to say that – in contrast to the WW2 – they indeed wouldn’t be very helpfull in terms of security. Actually, it’s like using the Klingon language from Star Trek, or Elvish from Lord of the Rings… as long as only a few know it, it might add a minimal bit of security. But nowadays, you can even take online courses to learn Klingon, Elvish, etc. Back in 194-something, the situation was quite different.


As an aside: I used the name “Joe” on purpose, since it was a commonly used nickname for US-American soldiers during World War 2. Another example of such a naming would be “Tommy“, which was used to hint at English soldiers.

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  • $\begingroup$ The USA did not have "encrypted radio" in WW2. The Navajo code was the only layer. The signal itself could (and was) easily intercepted. $\endgroup$ – Henno Brandsma Mar 27 '18 at 7:28
  • $\begingroup$ @HennoBrandsma I didn't mean encrypted radio as in scrambled signals, but rather as in coded communications — the encryption which was used to transmit/radio valuable messages. (Think: Purple, Enigma, ECM Mark Ii, etc. Also, you should note "Navajo code" != "plain Navajo language" The Navajo "windtalkers" transmitted tactical messages over military telephone or radio communications nets using formal or informally developed codes and code-words built upon their native languages.) $\endgroup$ – e-sushi Mar 28 '18 at 3:25
  • $\begingroup$ The "code" itself was rather primitive, the fact that even plain language was totally incomprehensible to the Japanese was the largest factor in its success. $\endgroup$ – Henno Brandsma Mar 28 '18 at 4:02
  • $\begingroup$ @HennoBrandsma I definitely won't disagree with that. Btw.: Should I reword something to enhance the answer, or did my comment clarification suffice? $\endgroup$ – e-sushi Mar 28 '18 at 4:09
  • $\begingroup$ I get what you mean. Let the comments stand as clarification. $\endgroup$ – Henno Brandsma Mar 28 '18 at 4:11
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The "descriptive" language aspects certainly adds ambiguity in the word-symbols used, and thus entropy. If a rocket is one time described as "a spear that giants appreciate as a marital aid", the next time as "an opaque bottle filled with what decisively gives things direction", yet another time as "wisps smoke and fire chasing a wisp of steel" or "what lives by an orange fart, and dies by an orange fart" (none of these are Navajo, they are my own twisted ad-hoc inventions) - there is very little similarity in multiple plaintexts that describe the same thing, while descriptions for completely different things would appear very similar when trying to establish a pattern - "a transparent bottle filled with what decisively frees men of direction" is more likely to describe supplies for the officer's mess...

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There were only 400 code talkers. In the wider context of a war spanning the pacific with millions of participants, there were bigger fish to fry.

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