QWERTY

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The roller set of the Enigma consists of three rotating rollers, the non-rotating reversing roller B (left) and the stationary entry roller ( stator ) on the far right.

QWERTZU is a special term used by the British code breakers in Bletchley Park (BP) before and during World War II when they were deciphering the German Enigma key machine . It describes the information of the exact wiring of the entry roller, which is important for the cryptanalysis , i.e. the link between the keyboard and the roller set of the machine.

background

During the Second World War, the backbone of German cryptography was formed by the Enigma, which was used by all three parts of the Wehrmacht, the army , the air force and the navy , to encrypt their secret communications. Long before the war, in 1932, Polish cryptanalysts working with the young Marian Rejewski succeeded in breaking into the Enigma system while working in the Polish decryption center, the Biuro Szyfrów (German: "Chiffrenbüro") . After the Poles had passed all their knowledge on to their allies at the legendary secret meeting in Pyry in July 1939 , British codebreakers succeeded in encrypting German radio messages with the Enigma I from January 1940 in Bletchley Park, England, about 70 km northwest of London , initially from the Air Force and shortly afterwards also by the army, to be deciphered. Contrary to the German hopes and assumptions, the radio messages encrypted by the German Navy using the Enigma M3 and - especially important for the war effort - the radio messages encrypted with the Enigma M4 machine used by the German submarines remained no secret for the British. Rather, they succeeded in breaking the Wehrmacht's encrypted communications with the aid of special cryptanalytic devices such as the Turing bomb for almost the entire duration of World War II and using the information obtained from it profitably under the code name " Ultra ".

technology

Sketch: Basic structure of the Enigma from
battery (1),
keyboard (2),
connector board (3, 7) with
plug-in cable (8),
roller set (5) with
entry roller (4) and reversing roller (6) as well as
the lamp field (9)

The principle and basic structure of the Enigma is described in the overview article. To the right of the three rotating rollers (5) of the roller set (see numbers highlighted in yellow in the schematic diagram) is the entry roller (4) ( stator ), which does not rotate and its contacts via 26 wires (only four of them are shown here) with the Letter keys (2) are connected. To the left of the roller set is the reversing roller (6) (VHF), which is also fixed. It is an invention (patented on March 21, 1926) by Willi Korn , an employee of Scherbius. It only has 26 contacts on its right-hand side (again only four of them are shown in the sketch), which are connected to one another in pairs. The reversing roller has the effect that the current, which initially passes through the roller set from right to left, is deflected and flows through it again, now from left to right. The current leaves the roller set as it came, again via the entry roller.

The entry roller (4) is the important link between the input element, i.e. the keyboard (2), and the cryptographic heart of the Enigma, namely the roller set, and also forms the connection between the roller set and the output element, namely the lamp field (9). In addition to the knowledge of the wiring of the three rotatable rollers used in the Enigma and the VHF (see also: Enigma rollers ), knowledge of the wiring of the entry roller is essential for the cryptanalysis of the machine, because the machine would remain "unbreakable" without clarifying the wiring .

history

Long before the Second World War, at the beginning of the 1930s, the cryptanalysts were already familiar with the basic structure and mode of operation of an Enigma machine, because at that time predecessor models of the Enigma I, which were later used for military purposes, were commercially available, which in principle differed little from one another . The code breakers already had a lot of basic information that was absolutely necessary for a successful “break” of the Enigma. What they still lacked was “the all-important internal wiring of the wheels” (German: “the crucial internal wiring of the rollers”). And an important element of that was the wiring of the entry roller.

The entry roller connects the 26 capital letters of the Latin alphabet given via the keyboard of the Enigma via 26 electrically insulated wires with 26 contacts which are located on the left side of the entry roller and which form the connection points to the set of rollers (rotating during the encryption process). There is an almost unmanageable number of possibilities for connecting the letter keys to the output contacts of the entry roller, which can be calculated with the help of the faculty . There are 26! possible wiring configurations are conceivable, i.e. 26 · 25 · 24 ··· 3 · 2 · 1 cases. That is exactly 403,291,461,126,605,635,584,000,000 possibilities for the wiring, of which the German cryptographers could choose any one for the military Enigma.

The British knew the appropriate wiring for the commercial machines. It was simply the identity, i.e. the connection of the keys, starting at the top left, with the output contacts of the entry roller (on its left side) in the order of the 26 letters on the Enigma's keyboard. 

 Q   W   E   R   T   Z   U   I   O 
   A   S   D   F   G   H   J   K 
 P   Y   X   C   V   B   N   M   L
The then 27-year-old Polish code breaker Marian Rejewski succeeded in uncovering the QWERTZU as early as 1932
In the Polish Enigma replica, of which at least 15 were made in the mid-1930s, buttons (1), lamps (2) and sockets (7), like the German Enigma-C , were simply arranged alphabetically.

For the military Enigma, however, as they quickly recognized, this wiring did not apply and the Germans had obviously decided on a different wiring sequence. The big question was for which one? Since this problem was of paramount importance for the desired deciphering of the Enigma, the British code breaker Dillwyn "Dilly" Knox , who was known to his colleagues in Bletchley Park for creating strange but concise terms , coined as an abbreviation for the unknown wiring sequence of the Entry roller of the Enigma I used by the military was named "QWERTZU".

As a synonym for QWERTZU, the term “diagonal” (English for “diagonal”) was also used in BP . This also meant the sequence of letters in which the individual letter keys of the Enigma I were connected to the entry roller.

Dilly Knox herself worked on this problem for many years, though not exclusively, until 1939 without finding a solution. Nor did his BP colleagues Tony Kendrick , Peter Twinn and even the great Alan Turing come up with the wiring chosen by the Germans, which in view of the immense number of possibilities for the QWERTZU did not surprise anyone. None of the cryptanalysts mentioned was even remotely suspected of being an “unimaginative dullard” . On the contrary, they were all valued at BP as extremely intelligent and creative minds. Still, none of them found the right QWERTZU.

The British did not obtain this important information until July 26th and 27th, 1939, when there was a legendary meeting of French, British and Polish code breakers in the Kabaty Forest of Pyry, about 20 km south of Warsaw, at which they stunned the British and French handed over their Enigma replicas and revealed their collected knowledge and developed cryptanalytic methodologies. The first question that Dilly Knox asked at this meeting (according to Mavis Batey in French) was: “Quel est le QWERTZU?” (German: “What is the QWERTZU?”; In other words: “What is the wiring order of the entry roller ? "). This had tormented him for so long. Rejewski's answer was ingeniously simple: "ABCDEFG ..."

The code breaker Peter Twinn, who also worked at BP, reports that Dilly Knox, after he and the Frenchman Gustave Bertrand returned from the Pyry meeting to the Hotel Bristol in Warsaw , where he and his boss "Alastair" Denniston during their Poland- Stayed, sang enthusiastically in French in the taxi: “Nous avons le QWERTZU, nous marchons ensemble” (German: “We have the QWERTZU, we will march together.”).

In retrospect, of course, the solution seems ridiculously simple, but from the point of view of the British specialists it was also the stupidest of all the options the Germans had chosen. With an astronomically large number of more than 400 quadrillion possibilities, the German cryptographers actually simply selected the usual alphabetical order as QWERTZU. From the British point of view, this was so absurd and so stupid, and therefore so unlikely, that they had never seriously considered this case. Marian Rejewski, on the other hand, had already guessed this sequence intuitively and correctly in 1932, thus creating the basis for the historically important Allied Enigma decipherments (code name: "Ultra") during the Second World War.

literature

  • Kris Gaj, Arkadiusz Orłowski: Facts and myths of Enigma: breaking stereotypes. Eurocrypt, 2003, p. 121ff. Accessed: February 6, 2012. PDF; 0.1 MB
  • Francis Harry Hinsley, Alan Stripp: Codebreakers - The inside story of Bletchley Park . Oxford University Press, Reading, Berkshire 1993. ISBN 0-19-280132-5
  • Tony Sale: The Bletchley Park 1944 Cryptographic Dictionary . Publication, Bletchley Park, 2001, p. 22. Accessed: Jan. 24, 2012. PDF; 0.4 MB
  • Hugh Sebag-Montefiore : Enigma - The battle for the code . Cassell Military Paperbacks, London 2004, ISBN 0-304-36662-5
  • Michael Smith: Enigma deciphered - The "Codebreakers" from Bletchley Park . Heyne, 2000. ISBN 3-453-17285-X

Individual evidence

  1. ^ Gordon Welchman: The Hut Six Story - Breaking the Enigma Codes . Allen Lane, London 1982; Cleobury Mortimer M&M, Baldwin Shropshire 2000, p. 11. ISBN 0-947712-34-8
  2. ^ Marian Rejewski: An Application of the Theory of Permutations in Breaking the Enigma Cipher . Applicationes Mathematicae, 16 (4), 1980, pp. 543–559, cryptocellar.org (PDF; 1.6 MB), accessed on May 27, 2019.
  3. ^ Gordon Welchman: The Hut Six Story - Breaking the Enigma Codes . Allen Lane, London 1982; Cleobury Mortimer M&M, Baldwin Shropshire 2000, p. 230. ISBN 0-947712-34-8
  4. ^ Patent specification Electrical device for encryption and decryption DRP No. 452 194. Accessed: February 6, 2012. PDF; 0.5 MB
  5. ↑ Louis Kruh, Cipher Deavours: The commercial Enigma - Beginnings of machine cryptography . Cryptologia, Rose-Hulman Institute of Technology, Taylor & Francis, Philadelphia PA 26.2002.1 (January). ISSN  0161-1194 Accessed : February 6, 2012. PDF; 0.8 MB ( Memento of the original from April 13, 2006 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.dean.usma.edu
  6. ↑ a b Peter Twinn: The Defense Enigma in Francis Harry Hinsley, Alan Stripp: Codebreakers - The inside story of Bletchley Park . Oxford University Press, Reading, Berkshire 1993, p. 126. ISBN 0-19-280132-5
  7. ^ Krzysztof Gaj: Polish Cipher Machine -Lacida . Cryptologia . Rose-Hulman Institute of Technology. Taylor & Francis, Philadelphia PA 16.1992,1, ISSN  0161-1194 , p. 74.
  8. ↑ Tony Sale: The Bletchley Park 1944 Cryptographic Dictionary . Publication, Bletchley Park, 2001, p. 28. Accessed: February 6, 2012. PDF; 0.4 MB
  9. ↑ a b Peter Twinn: The Defense Enigma in Francis Harry Hinsley, Alan Stripp: Codebreakers - The inside story of Bletchley Park . Oxford University Press, Reading, Berkshire 1993, p. 127. ISBN 0-19-280132-5
  10. ↑ Ralph Erskine: The Poles Reveal their Secrets - Alastair Dennistons's Account of the July 1939 Meeting at Pyry . Cryptologia. Rose-Hulman Institute of Technology. Taylor & Francis, Philadelphia PA 30.2006,4, p. 294
  11. ^ Kris Gaj, Arkadiusz Orłowski: Facts and myths of Enigma: breaking stereotypes. Eurocrypt, 2003, p. 121ff. Accessed: February 6, 2012. PDF; 0.1 MB
  12. ^ Mavis Batey: Dilly Knox - A Reminiscence of this Pioneer Enigma Cryptanalyst. Cryptologia, Rose-Hulman Institute of Technology. Taylor & Francis, Philadelphia PA 32.2008,2, pp. 104-130.
  13. ↑ Friedrich L. Bauer : Deciphered secrets. Methods and maxims of cryptology. 3rd, revised and expanded edition. Springer, Berlin et al. 2000, ISBN 3-540-67931-6 , p. 412.
  14. ^ Hugh Sebag-Montefiore: Enigma - The battle for the code . Cassell Military Paperbacks, London 2004, p. 42. ISBN 0-304-36662-5
  15. ↑ Michael Smith: Enigma decrypted - The "Codebreakers" from Bletchley Park . Heyne, 2000, p. 40. ISBN 3-453-17285-X
  16. ↑ Michael Smith: Enigma decrypted - The "Codebreakers" from Bletchley Park . Heyne, 2000, p. 39. ISBN 3-453-17285-X