The Poles and Enigma

LINKS to other pages in the Bletchley Park site and to the Colin Day Travelling Days series:

1 : Bletchley Park Estate to 1939
2 : Enigma and GC&CS.
3 : The Poles and Enigma
4 : Turing and the Bombes
5 : The Huts: An overview
6 : German Naval Codes
7 : Huts 3,4,6 and 8
8 : Blocks A,B,C,D,E and F
9 : Views of the Estate (1)
10 : Views of the Estate (2)
11 : Lorenz and Colossus
12 : Finale, Links, Bibliography
Bletchley Park Guest Book:

BletchleyextPoleMema.jpg - 55803 Bytes MEANWHILE, in 1929 a commercial model of the Enigma machine had fallen into the hands of the Poles while it was en route from Berlin to Warsaw. After inspecting it the Poles realised Enigma’s potential for military use.

   When the German Army started using the machine a few years later, the Poles were able to determine the wiring of the rotors then in use by the German Army and, with the help of reconstructed models of the machine, were later able to decrypt a large portion of German Army traffic.

   The picture on the right shows the sculpture in the stable-yard commemorating the part played by the Poles in the Enigma story.

   Polish mathematician Marian Rejewski and co-workers Henryk Zigalski and Jerzy Rozycki had managed to build up a table of relationships involving chains of letters from studying these message-keys, Bletchleyenig16aa.jpg - 52599 Bytesbut was still faced with the problem of identifying the correct day-setting. Finding the proper chains from the 105456 possiblilities had been a difficult task.

   The Poles (particularly Rozycki and Zygalski), developed a technique using perforated sheets for each rotor showing which letters could be chained. Users would stack the sheets and determine where the three letters were clear all the way through. But they were still faced with the problem of identifying the correct day-key with its several thousand possibilites. To help with this, the Poles eventually designed a machine called a bomba that resembled three pairs of Enigma machines linked together. AVA Radio Manufacturing Company (Wytwornia Radiotechniczna AVA) - the same company that built the Polish copies of the Enigma - went on to build a number of the new machines

   In 1939 the German Army increased the complexity of their Enigmas. Previously it had used just three rotors and simply moved them from slot to slot., enigmaplan.jpg - 44558 BytesWith the introduction of an additional two rotors each day the army could now select three rotors from a choice of five. Rajewski now had to work out the wiring of the two new wheels and to build ten times as many Bomby, each representing a different rotor arrangement.

   The following month the situation worsened when the Germans increased the number of plugboard cables from six to ten. The total number of possible keys increased to 159,000,000,000,000,000,000. It was more than the Polish system was capable of handling.

   The diagram of the Enigma machine on the right shows how the path from the keyboard to the lamp board may convert the letter 'Q' into the letter 'U'. The added dimension of the plugboard is not shown.

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   The Poles decided, in mid-1939, to share their work, and in July they met with French and British cryptographers (including Denniston) in the Pyry Forest in Poland and passed to them some of their home built 'Enigmas' and information on the team’s breakthrough, and on the other techniques they had developed. One of the Enigma copies eventually arrived at Bletchley Park.

   Most of the Polish cryptographers left Poland during the invasion and many went to France where they worked with French cryptographers on German transmissions until the fall of France. Some of the French and Polish teams escaped to England but none were employed at Bletchley Park.

   Rozycki died as a result of an accident in 1942; Zygalski died in England in 1978.........................

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