209m

In cryptography, the M-209, designated CSP-1500 by the United States Navy (C-38 by the manufacturer) is a portable, mechanical cipher machine used by the US military primarily in World War II, though it remained in active use through the Korean War. The M-209 was designed by Swedish cryptographer Boris Hagelin in response to a request for such a portable cipher machine, and was an improvement of an earlier machine, the C-36.
The M-209 is about the size of a lunchbox, in its final form measuring 3 1⁄4 by 5 1⁄2 by 7 inches (83 mm × 140 mm × 178 mm) and weighing 6 pounds (2.7 kg) (plus 1 pound (0.45 kg) for the case). It represented a brilliant achievement for pre-electronic technology. It used a wheel scheme similar to that of a telecipher machine, such as the Lorenz cipher and the Geheimfernschreiber.

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