Rolf Noskwith

Rolf Noskwith (93) on August 4, 2012 as a speaker at a conference in Halifax, Canada

Rolf Noskwith (born  June 19, 1919 in Chemnitz ; † January 3, 2017 in London ) was a British cryptanalyst . During the Second World War he contributed to the breakage of the Enigma-M4 rotor key machine used by the German submarines in the Government Code and Cypher School (GC&CS) (German: "Staatliche Code- und Chiffrenschule") in Bletchley Park, England .

Life

youth

Rolf was born in Chemnitz to a Jewish family who emigrated to England in 1932. There he attended Nottingham High School and then Trinity College , Cambridge .

Bletchley Park

During the Second World War, the site of the Bletchley Park (BP) country estate in Buckinghamshire was the location of the military service that successfully deciphered German communications. It was housed in different "hats" (German: "barracks"). The Codebreaker in Hut Eight (German: "Baracke 8") dealt under the direction of Alan Turing and his deputy Hugh Alexander with the breaking of radio messages of the German Navy , which used the Enigma-M3 and the Enigma-M4 for encryption.

In the war year 1941, Rolf Noskwith was recruited by Hugh Alexander to serve in BP. He entered the site for the first time on his 22nd birthday and was assigned to the "Crib Room" , the department of Hut 8 , which, under the direction of Shaun Wylie , searched for suspected clear text fragments (English: " Cribs " ) in German radio messages. The encrypted German weather reports were particularly suitable for this due to their stereotypical structure. Usually, the German radio stations broadcast a weather report every day from the same place and at the same time, which often began with the same words.

The German regulation “General key rules for the Wehrmacht” ( H.Dv. g. 7) expressly forbade “regularities in the structure, identical expressions and repetitions in the text” and warned urgently “It must be avoided in any case that by fleetingly trained Personnel key mistakes are made that [...] enable enemy intelligence to decipher, ” but precisely these mistakes happened that the code breakers could perceive and exploit. Noskwith remembers that the Enigma key from " D-Day " , the day the Allies landed in Normandy ( Operation Overlord ) , was saved by the crib "WEATHER FORECAST ISKAYA", which the British cryptanalysts were able to guess correctly, in less than was broken two hours after midnight. This meant that they could decode and read the German radio messages all day just as easily as the authorized German receivers.

In order to induce the Germans to send radio messages with known content, the British used a special method that they called “ gardening ” ( German  literally: “gardening” ) and which Rolf Noskwith described as follows: “The RAF threw at certain Put mines in the North Sea so that the German mine warning served as a crib. The digits were carefully selected in order to avoid certain digits, such as 0 and 5 in particular, for which the Germans used different letters. ”The British were able to avoid the distinction between“ ZERO ”and“ NUL ”and“ FUENF ”. and "FUNF", which make cryptanalysis a little easier, because apart from the "ZWEI" and "ZWO" cases, there was only one notation for the other digits.

The German rear admiral Ludwig Stummel, who was responsible for the security of radio communications in the Kriegsmarine, tried to improve this by assigning each submarine its own independent key network from mid-1944. Rolf Noskwith said: "The following division of the main keys [networks] was really helpful, because the same message often appeared in different keys [etzen], sometimes on different days." (In the original: The subsequent proliferation of main keys [ ...] was actually helpful, because the same message would often appear in several keys, sometimes on different days. )

So-called “officer radio messages” turned out to be particularly difficult to “crack” because the Germans encrypted them twice using their encryption machine. Here too, the "Hut 8 cribster" Rolf Noskwith dealt with success. During a special radio message, he suspected that instructions for the use of light signals were being transmitted and tried the crib "EEESSSPATRONE" (then the usual abbreviated notation for "detection signal cartridge"; see also ES slider ). His assumption turned out to be absolutely correct and led to the breakage of this and subsequent officer radio messages.

The British code breakers from Bletchley Park succeeded in maintaining the Enigma's ability to decipher, with the exception of a few interruptions, for the entire period of the war and thus contributed significantly to the rapid victory of the Allies.

Noskwith stayed at Hut 8 until the end of the war in 1945 .

After the war

From 1946 until around 2000 he worked, most recently in a managerial position, in the Charnos textile factory , which his father Charles Noskwith had founded. In contrast to almost all of his colleagues, who, due to the strict secrecy of their military achievements, no longer received any public recognition during their lifetime, Rolf Noskwith died as one of the last BP codebreakers at the age of 97.

Works

• Hut 8 and naval Enigma, Part II . In Francis Harry Hinsley , Alan Stripp: Codebreakers - The inside story of Bletchley Park . Oxford University Press, Reading, Berkshire 1993, pp. 119-122. ISBN 0-19-280132-5

literature

• 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. 400.
• Francis Harry Hinsley, Alan Stripp: Codebreakers - The inside story of Bletchley Park . Oxford University Press, Reading, Berkshire 1993, pp. 119-122. ISBN 0-19-280132-5
• Hugh Sebag-Montefiore : Enigma - The battle for the code . Cassell Military Paperbacks, London 2004, pp. 174-176. ISBN 0-304-36662-5

Web links

• Photo accessed on May 22, 2015.

Individual evidence

1. ^ ^{A b} Francis Harry Hinsley, Alan Stripp: Codebreakers - The inside story of Bletchley Park . Oxford University Press, Reading, Berkshire 1993, p. 119. ISBN 0-19-280132-5
2. ↑ website Special Forces Roll of Honor, . Retrieved January 4, 2017.
3. ^ Jewish Bletchley Park code-breaker dies aged 97 . The Times of Israel of January 3, 2017 (English). Retrieved January 4, 2017.
4. ↑ Obituary: Rolf Noskwith, Bletchley codebreaker and hosiery manufacturer ( Memento of the original from January 10, 2017 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Nottingham Post, January 9, 2017. Retrieved February 1, 2017.  
5. ^ Hugh Sebag-Montefiore: Enigma - The battle for the code . Cassell Military Paperbacks, London 2004, p. 174. ISBN 0-304-36662-5
6. ^ 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
7. ↑ High Command of the Wehrmacht: General key rules for the Wehrmacht . H.Dv.g. 7, Reichsdruckerei , Berlin 1944, p. 10. Accessed on August 26, 2010. PDF; 0.9 MB
8. ↑ High Command of the Wehrmacht: General key rules for the Wehrmacht . H.Dv.g. 7, Reichsdruckerei , Berlin 1944, p. 6. Accessed August 26, 2010. PDF; 0.9 MB
9. ^ ^{A b} Francis Harry Hinsley, Alan Stripp: Codebreakers - The inside story of Bletchley Park . Oxford University Press, Reading, Berkshire 1993, p. 121. ISBN 0-19-280132-5
10. ↑ ^{a b} Friedrich L. Bauer: Deciphered secrets. Methods and maxims of cryptology. 3rd, revised and expanded edition. Springer, Berlin et al. 2000, p. 400.
11. ↑ Michael Smith: Enigma decrypted - The "Codebreakers" from Bletchley Park . Heyne, 2000, p. 107. ISBN 3-453-17285-X
12. ^ Hugh Sebag-Montefiore: Enigma - The battle for the code . Cassell Military Paperbacks, London 2004, p. 295. ISBN 0-304-36662-5
13. ^ Francis Harry Hinsley, Alan Stripp: Codebreakers - The inside story of Bletchley Park . Oxford University Press, Reading, Berkshire 1993, p. 120. ISBN 0-19-280132-5
14. ^ Hugh Sebag-Montefiore: Enigma - The battle for the code . Cassell Military Paperbacks, London 2004, p. 175. ISBN 0-304-36662-5