A brief history of Enigma

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A brief history of Enigma

Postby Ty N. » 15 Dec 2014 19:43


The Enigma family included multiple designs. The earliest were commercial models dating from the early 1920s. Starting in the mid-1920s, the German military began to use Enigma, making a number of security-related changes. Various nations either adopted or adapted the design for their own cipher machines.

On 23 February 1918, German engineer Arthur Scherbius applied for a patent for a cipher machine using rotors and, with E. Richard Ritter, founded the firm of Scherbius & Ritter. They approached the German Navy and Foreign Office with their design, but neither was interested. They then assigned the patent rights to Gewerkschaft Securitas, who founded the Chiffriermaschinen Aktien-Gesellschaft (Cipher Machines Stock Corporation) on 9 July 1923; Scherbius and Ritter were on the board of directors.
Chiffriermaschinen AG began advertising a rotor machine—Enigma model A—which was exhibited at the Congress of the International Postal Union in 1923–1924. The machine was heavy and bulky, incorporating a typewriter. It measured 65×45×35 cm and weighed about 50 kilograms (110 lb).

In 1925 Enigma model B was introduced, and was of a similar construction. While bearing the Enigma name, both models A and B were quite unlike later versions: they differed in physical size and shape, but also cryptographically, in that they lacked the reflector. The reflector—suggested by Scherbius's colleague Willi Korn—was introduced in Enigma C (1926). Model C was smaller and more portable than its predecessors. It lacked a typewriter, relying on the operator; hence the informal name of "glowlamp Enigma" to distinguish it from models A and B. The Enigma C quickly gave way to Enigma D (1927). This version was widely used, with shipments to Sweden, the Netherlands, United Kingdom, Japan, Italy, Spain, United States and Poland.

German military texts enciphered on the Enigma machine were first broken by the Polish Cipher Bureau, beginning in December 1932. This success was a result of efforts by three Polish cryptologists, Marian Rejewski, Jerzy Różycki and Henryk Zygalski, working for Polish military intelligence. Rejewski "reverse-engineered" the device, using theoretical mathematics and material supplied by French military intelligence. Subsequently the three mathematicians designed mechanical devices for breaking Enigma ciphers, including the cryptologic bomb. From 1938 onwards, additional complexity was repeatedly added to the Enigma machines, making decryption more difficult and necessitating larger numbers of equipment and personnel—more than the Poles could readily produce.

On 25 July 1939, in Warsaw, the Poles initiated French and British military intelligence representatives into their Enigma-decryption techniques and equipment, including Zygalski sheets and the cryptologic bomb, and promised each delegation a Polish-reconstructed Enigma. The demonstration represented a vital basis for the later British continuation and effort.

The British bombe was an electromechanical device designed by Alan Turing soon after he arrived at Bletchley Park in September 1939. Harold "Doc" Keen of the British Tabulating Machine Company (BTM) in Letchworth (35 kilometres (22 mi) from Bletchley) was the engineer who turned Turing's ideas into a working machine—under the codename CANTAB. Turing's specification developed the ideas of the Poles' bomba kryptologiczna but was designed for the much more general crib-based decryption.

Though Enigma had some cryptographic weaknesses, in practice it was German procedural flaws, operator mistakes, laziness, failure to systematically introduce changes in encipherment procedures, and Allied capture of key tables and hardware that, during the war, enabled Allied cryptologists to succeed.

The Italian Navy adopted the commercial Enigma as "Navy Cipher D". The Spanish also used commercial Enigma during their Civil War. British codebreakers succeeded in breaking these machines, which lacked a plugboard. Not only militaries used the Enigma, they were also used by diplomatic services.

The Swiss used a version of Enigma called model K or Swiss K for military and diplomatic use, which was very similar to commercial Enigma D. The machine was cracked by Poland, France, the United Kingdom and the United States (the latter codenamed it INDIGO). An Enigma T model (codenamed Tirpitz) was used by Japan.

An estimated 100,000 Enigma machines were constructed. After the end of World War II, the Allies sold captured Enigma machines, still widely considered secure, to developing countries. As these countries did not know that the machine had been broken, their supposedly secure communications were being read regularly by the major Western intelligence agencies.
Ty N.
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Re: A brief history of Enigma

Postby Monzambano » 17 Dec 2014 00:49

Great reminder.

Bletchley Park - worth a visit

The best revenge is living well
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