Japanese Red Analog

In the era of electromechanical crypto machines, an analog is a device developed to "crack " a cipher.

William Friedman, Chief of the Army's Signal Intelligence Service, envisioned an electromechanical machine to rapidly decrypt RED messages. It would work much like the Japanese Cipher Machine Type A, however funding was not available.

For more than two years, the Army cryptoanalysts used handmade analogs that consisted of thin, plastic, sixty-point disks with the "sixes and twenties" continuously written along the periphery of each disk

In the late 1930's, the Navy Yard model shop constructed the first electromechanical RED analog.  The machine mimicked the actions of the Cipher Machine Type A with its commutators for the sixes and twenties plus the plugboard. A braking wheel controlled the stepping motion.

Various views of the electromechanical RED analog. (All photos in this table by Ralph Simpson) 

This is a hand operated RED analog. (Photo by Ralph Simpson)

Contributors and Credits:

1) Ralph Simpson <ralphenator(at)gmail.com>
2) RED analog placard in display case at NCM.

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Apr 15/12