US Army Field Manual: Basic Cryptanalysis (1990)

Got &#x27;Authentication Required&#x27;<p>Google found me this. Least seedy looking source I could find.<p><a href="http:&#x2F;&#x2F;www.globalsecurity.org&#x2F;intell&#x2F;library&#x2F;policy&#x2F;army&#x2F;fm&#x2F;34-40-2&#x2F;index.html" rel="nofollow">http:&#x2F;&#x2F;www.globalsecurity.org&#x2F;intell&#x2F;library&#x2F;policy&#x2F;army&#x2F;fm&#x2F;...</a>

<a href="http:&#x2F;&#x2F;www.und.nodak.edu&#x2F;org&#x2F;crypto&#x2F;crypto&#x2F;army.field.manual&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.und.nodak.edu&#x2F;org&#x2F;crypto&#x2F;crypto&#x2F;army.field.manual...</a> contains zipped pdfs for each chapter.

I really like that this includes frequency tables for tetragraphs.<p>I had to laugh a little at the fact that &quot;STOP&quot; is the 5th most frequently used tetragraph though.