Cryptography Stack Exchange is a question and answer site for software developers, mathematicians and others interested in cryptography. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I've got an academic curiosity regarding some of the old Japanese naval codes used during World War II specifically. I'm wondering if any of the codebooks from this era have been made available, or if they are still protected materials?

share|improve this question
Most WW2-era material has been made public. I doubt they're still classified. Have you tried contacting a museum? Keith Lockstone's website has a scan of a British codebook (Cypher No. 5) – rath Apr 21 '14 at 18:52
Perhaps the NSA has some? – mikeazo Apr 21 '14 at 18:59
up vote 2 down vote accepted

Yes, a good bunch of Japanese naval codebooks and related documents from WWII are available.

You might want to contact the National Archives and Records Administration (NARA) for that, as they hold the related NSA documents which have been declassified.

The “Declassified Documents Released to NARA” list at the NSA website points (among other things) to ample Japanese naval codebooks (random example: “NR 4037, ZEMA150, 45441A, 19440218, CODES AND CIPHERS: JAPAN JN-155 CODEBOOK”) as well as dozens of similar documents containing Japanese naval codebooks, naval call-signs, naval communications indicators, brevity codes, etc.

Looking at The Freedom of Information Act, it shouldn’t pose a big problem to get a copy of those documents to satisfy your academic curiosity.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.