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B-211 →
K-37   Crystal
Russian copy of Hagelin B-211 - wanted item

K-37 was a mechanical cipher machine, designed and build by the Russians in the USSR, shortly before the start of WWII. The machine was a functional copy of the Hagelin B-211, but was missing the input/output matrix wires (plugboard). The K-37 was used by the Russians throughout WWII and even for a few years after the war. The machine is also known as Crystal.

The K-37 is in fact a copy of the Hagelin B-211, which in turn was a further development of the B-21. The machine printed directly onto a paper strip and had a built-in wheel-based encryption mechanism that was based on a matrix.

The original Hagelin machine featured a 5 x 5 matrix in order to accomodate 25 letters of the Latin alphabet. The Russians modified it and used a 5 x 6 matrix, so that 30 (of the 33) characters of the Cyrillic alphabet could be used. Strangely, the Russians omitted the input and output plugboard of the original design, so that the machine became cryptographically weaker.

The image above shows a top view of the K-37 after the top cover has been removed. Immedately at the front is the keyboard with its 30 keys. The rear part contains the cipher wheels (left), a printer (center) and a set of relays (right) that prevented the electric current from flowing in the wrong direction. When typing, the entire mechanism is driven by a motor that is mounted at the rear right. Paper is fed past the print head through a metal gutter behind the keyboard.

  1. Boris Hagelin, 100 Jahre Boris Hagelin 1892-1992
    Memoires of Boris Hagelin (German).
    Crypto A.G., Crypto Hauszeitung Nr. 11, September 1992.

  2. Boris Hagelin, The Story of Hagelin-Cryptos
    Crypto A.G., Zug, Spring 1981. Based on [6].

  3. Christos Triantafyllopoulos, The Soviet K-37 'Crystal' cipher machine
    Christos military and intelligence corner. 14 June 2012. Retrieved November 2012.

  4. VV Babievsky, LS Butyrsky, DA Larin; Soviet cryptographic service 1920-1940
    Website (Russian). Retrieved June 2012.

  5. Crypto Museum, Hagelin B-21 and B-211

  6. TICOM I-58, Interrogation of Dr. Otto Buggisch of OKW.CHI
    8 August 1945. Declassified. p. 5.
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Crypto Museum. Created: Thursday 06 November 2121. Last changed: Saturday, 24 February 2018 - 07:24 CET.
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