Margaret Alice Rock ( July 7, 1903 in Hammersmith , † August 26, 1983 in Worcester ) was a British cryptanalyst and one of the women in Bletchley Park . During the Second World War , she contributed to the Government Code and Cypher School in the English Bletchley Park , the military service that successfully deciphered German communications, essential to breaking the German rotor key machine Enigma .
Margaret was the daughter of Dr. Frank Ernest Rock and his wife Alice Maud Fanny Rock, b. Simmonds, and was born two years before her brother, the future paratrooper for the British Royal Airborne Engineers , Lt. Col. (German: Lieutenant Colonel ) John Frank Rock, born in England . As a girl, she attended North Middlesex School in Enfield and then Portsmouth High School in the southern English seaside resort of Southsea near Portsmouth . She then studied mathematics with a focus on statistics and languages with a focus on French and German at Bedford College .
After the outbreak of World War II, she joined the Government Code and Cypher School (GC & CS) in Bletchley Park (BP), 70 km north-west of London on April 15, 1940 . From her new boss, the renowned codebreaker Dillwyn Knox , who was called “Dilly” by everyone, she received the usual brief greeting, which also had to serve as an introduction to the new task: “Hello, we're breaking machines. Have you got a pencil? Here, have a go. ”(German:“ Hello, we're breaking machines. Do you have a pencil? Here, try it out. ”) Together with Mavis Lever , who started at“ Dilly ”the same month, and with the she quickly became friends and remained friends her entire life, she now worked on deciphering German radio messages encrypted with the Enigma . Like her colleague Mavis and Alan Turing's colleague Joan Clarke , she was one of the very few female code breakers in BP
Your boss very much appreciated the collaboration of his two capable employees, who were highly respected in BP as "Dilly's girls", and praised them with the words "Give me a lever and a rock and I will move the universe." Give me a lever and a rock and I'll move the universe ”as a play on words with the surnames of his two co-workers ( Lever German lever and Rock German rock) to read as“ Give me a lever and a rock and I will create the universe move ”with unquestionable reference to the quote attributed to Archimedes on his law of leverage “ Give me a fixed point and I will turn the world off its hinges ”).
On December 8, 1941, Margaret Rock achieved an important cryptanalytic breakthrough when she and Mavis “cracked” a message encrypted by the German Abwehr (secret service) using a special Enigma model (G) for the first time . In doing so, she made an important contribution to the fact that German agents could be “received” as soon as they entered the country. These were not simply eliminated afterwards, but the British domestic secret service MI5 succeeded in "turning around" many of them and using them as double agents within the framework of the Double Cross system (German: "Doppelkreuz") . Together with the information deciphered from Enigma-G sayings, the MI5 received such a detailed and accurate picture of the plans and the level of knowledge of the defense that every single German agent still operating in Great Britain was precisely known and could be specifically controlled and manipulated. This was also used to disinformation for the German leadership ( Operation Fortitude ) and, among other things, contributed significantly to the Allied success on D-Day , i.e. the successful landing of the Allies in Normandy ( Operation Overlord ).
In May 1943 Margaret achieved another important success when she succeeded in breaking into a radio line used by the Germans from weather ships near the Canary Islands to transmit weather reports that were encrypted with a special Enigma.
Margaret was awarded the Order of the British Empire (MBE) in 1945 for her services . She stayed with the GC & CS and the successor organization, the GCHQ (Government Communications Headquarters) , until she retired in July 1963. She was unmarried and later lived with her long-time friend, Norah Sheward, who she was from the North Middlesex School knew. Margaret Rock died at the age of 80.
- 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.
- Mavis Batey: Dilly - The Man Who Broke Enigmas . Dialogue, 2011. ISBN 1-906-44715-2 .
- 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 .
- Francis Harry Hinsley , Alan Stripp: Codebreakers - The inside story of Bletchley Park . Oxford University Press, Reading, Berkshire 1993. ISBN 0-19-280132-5
- Kerry Howard: Dear Code Breaker - The Letters of Margaret Rock (Bletchley Park Code Breaker) & John Rock (Parachute & Glider Forces Pioneer) . BookTower Publishing, Redditch 2013. ISBN 0-955-71645-4
- Gordon Welchman : The Hut Six Story - Breaking the Enigma Codes . Allen Lane, London 1982; Cleobury Mortimer M&M, Baldwin Shropshire 2000. ISBN 0-947712-34-8
- Portrait photo of Margaret
- Another shot with a quote from Dilly Knox.
- Margaret rock in the honor roll (Roll of Honor) of Bletchley Park
- Photo of Margaret after the war (around 1955).
- Women Codebreakers (English). With posters of Margaret, Mavis and Joan.
- Curriculum vitae with youth portrait photo ( Memento from June 10, 2015 in the Internet Archive ) (English).
- Information on Margaret from BP .
- Website from Kerry Howard with video about Margaret.
- CV of her brother Lt. Col. John Frank Rock (English).
- ^ BP Roll of Honor (English). Retrieved June 11, 2015.
- ↑ a b Women Codebreakers Information from BP Retrieved June 10, 2015.
- ^ The University of Manchester ( Memento June 10, 2015 in the Internet Archive ) Margaret's CV. Retrieved June 10, 2015.
- ^ 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
- ↑ Women Code Breakers - Forgotten by History.Retrieved June 11, 2015.
- ^ Mavis Batey: Dilly Knox - A Reminiscence of this Pioneer Enigma Cryptanalyst. Cryptologia , Rose-Hulman Institute of Technology. Taylor & Francis, Philadelphia PA 32.2008,2, p. 124.
- ^ Hugh Sebag-Montefiore: Enigma - The battle for the code . Cassell Military Paperbacks, London 2004, p. 129. ISBN 0-304-36662-5
- ↑ Michael Smith: Enigma decrypted - The "Codebreakers" from Bletchley Park . Heyne, 2000, pp. 190ff. ISBN 3-453-17285-X
- ↑ Mavis Batey: Dilly - The Man Who Broke Enigmas . Dialogue, 2011, p. 211. ISBN 1-906-44715-2
|ALTERNATIVE NAMES||Rock, Margaret Alice (full name)|
|BRIEF DESCRIPTION||British cryptanalyst|
|DATE OF BIRTH||July 7, 1903|
|PLACE OF BIRTH||Hammersmith|
|DATE OF DEATH||August 26, 1983|
|Place of death||Worcester|