New answers tagged historic
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 ...
There are diagnostic programs that will tell you the cipher type from a statistical analysis. For example: http://bionsgadgets.appspot.com/gadget_forms/refscore.html tells you immediately that this cipher is a Playfair.
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