1). United States Cryptologic History, Sources in Cryptologic History, Volume 4, A Collection of Writings on Traffic Analysis, Vera R. Filby, Center For Cryptologic History,National Security Agency, 1993.2). United States Cryptologic History, Special Series, Volume 6, It Wasn’t All Magic: The Early Struggle to Automate Cryptanalysis, 1930s – 1960s, Colin B. Burke, Center For Cryptologic History, National Security Agency, 2002.
The study on the use of cryptanalytic equipment has details on the use of IBM punch card machines for codebreaking work, US efforts to solve the Enigma cipher machine using statistical theory rather than the crib based approach of Bletchley Park, the Soviet cipher machines Coleridge, Longfellow and Albatross, Japanese cipher machines of WWII (Purple, Coral and Jade) etcThere is also an interesting story regarding the Japanese Navy and the US strip cipher .Apparently the Japanese were so impressed by the US strip system that they copied it and started using it in mid 1944.
In page 148 it says: ‘JN87’s device was quite like the American Navy's own strip cipher. The '87 had a plastic board holding strips that had alphabets printed on both sides. There was a stock of one hundred two-sided strips to choose from. Thirty at a time were placed in the board, with their particular vertical and horizontal arrangement set according to complex specifications given in a book of instructions.’This system became a major target of the American codebreakers and its solution required the development and introduction of special cryptanalytic equipment.
In page 149 it says: ‘Steinhardt's Gypsy was a get-the job- done machine. It was a large, 4,000-pound stepping-switch and plugboard combination that required a central control unit and five separate six-foot high bays. Each of the bays contained five large plugboards. Each board was hand-wired to represent four of the JN87 strips. Because the strips were two-sided, the Gypsy plugboards were constructed to represent eight choices.’
It would be interesting if someone knowledgeable was able to compare the US methods of solution of the strip cipher and the equipment they built with the German techniques and their ‘Tower Clock’ machine.