578:
L |W V| |V U| E |U T| |T S| |S R| K |R Q| S |Q P| |P O| |O N| N |N M| X |M L| W T |L K| X Y |K J| W X |J I| |I H| Q |H G| |G F| |F E| A |E D| |D C| V |C B| J |B A| P |A ---------------------------------------------------------- A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
390:
positions, a notch on the right-most rotor engaged with the middle rotor so that the two rotors advanced together, and similarly the middle rotor would engage with the left-most rotor, giving a very long period before the sequence repeated (26 × 26 × 26 = 17,576). The ring on the rotor that contained the notch and so caused the next rotor to advance, could be set to any one of the 26 positions. The three rotors were selected from a set of five, giving 60 different ways of mounting rotors in the machine. However, because the
Germans laid down the rule that no rotor should be in the same position on successive days, if the previous days's rotors and their positions were known, this number was reduced to 32.
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mounted on their axle or after they had been inserted into the machine. It was possible to adjust the ring settings of the loaded rotors by moving the spring-loaded retaining pin to the right and turning the rotor to display the specified letter. Herivel thought it likely that at least some of the operators would adjust the rings after they had mounted the rotors in the machine. Having set the alphabet rings and closed the lid, the operator should then have moved the rotors well away from the positions that displayed the three letters of the ring setting in the windows, but some operators did not.
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557:
in a grid termed a "Herivel square", an example of which is shown below. The rows and columns of the grid are labelled with the alphabet. The first indicator of the first message of the day received from each station on the network, was entered into the grid. It was done by finding the column corresponding to the first letter, the row corresponding to the second letter, and entering the third letter into the cell where the row and column intersected. For example,
460:
348:
31:
1281:, p. 81 states that Bletchley looked for the clusters but did not find any until May 1940. "After the Germans altered their indicator system on 1 May 1940, which meant that no Enigma messages, other than those in Norway, were being read, Herivel's idea became even more important, since it was one of the few leads that the codebreakers had."
363:, another Cambridge mathematician recruited by Welchman, in nearby Elmers School, testing candidate solutions and working out plugboard settings. The process was slow, however, Herivel was determined to find a method to improve their attack, and he would spend his evenings trying to think up ways to do so.
577:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z ---------------------------------------------------------- Z| |Z Y| S |Y X| |X W|
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that was common to all operators on that network. At the start of each day, before any messages were sent or received, Enigma operators implemented the day's rotor selection and ring settings. Having selected the three rotors, they adjusted the ring settings. That could be done before the rotors were
1266:
However, on the 1st of May, the
Germans changed their methods, rendering the existing techniques inoperable. Alan Turing and his team had already anticipated this change, and were building a machine (the Bombe – in effect a computer) to decode the messages. That left a people from the 1st of May to
556:
The day after his insight, Herivel's colleagues agreed that his idea was a possible way into Enigma. Hut 6 began looking for the effect predicted by the
Herivel tip and arranged to have the first messages of the day from each transmitting station to be sent to them early. They plotted the indicators
471:
Herivel's great insight came to him one evening in
February 1940 while he was relaxing in front of his landlady's fire. Stressed or lazy operators who had set the rings when the rotors were in the machine might then have left ring setting at or near the top and used those three letters for the first
393:
The Enigma machine worked reciprocally so that an identical machine with identical settings would, if fed the enciphered letters, show the deciphered letters on the lampboard. Hut 6 had Enigma replica machines that were logically identical to the machines that the
Germans were using. To decipher the
532:
in the above example) should have been chosen at random, but
Herivel reasoned that if operators were lazy, in a hurry or otherwise under pressure, they might simply use whatever rotor setting was currently showing on the machine. If that was the first message of the day and the operator had set the
692:
I was absolutely astonished. He was a wonderful teacher, in the old fashioned way. During his tutorials he used to make tea and toast crumpets by the fire. (He was) a very profound thinker but very unexpected in his approaches but there was no sense that he had done anything extraordinary with his
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that set an electrical pathway from the keyboard to the lampboard. Pressing a key caused one lamp to light and the right-most rotor to advance by one letter position. This changed the electrical pathway so that pressing the same key again caused a different letter to light up. At one of the 26
640:
If
Herivel had not been recruited in January 1940, who would have thought of the Herivel tip, without which we would have been defeated in May 1940 – unable to maintain continuity until the bombes began to arrive many months later? Let there be no misconceptions about this last point. Loss of
609:
Although the
Herivel tip provided the Enigma's ring settings, it did not provide other parts of the Enigma key: the rotor order and the plugboard settings. A Luftwaffe key at the time chose from 5 rotors, so there were 60 possible rotor orders. In addition, there might be 8 to 10 plugboard
816:
The research on which this paper is based was carried out in Paris in 1964 with the aid of a Bourse de Marque awarded by the French
Government through their Embassy in London, and with a grant from the Research Committee of the Academic Council of the Queen's University,
593:", which had been passed on by Polish cryptologists. The situation changed on 1 May 1940, when the Germans changed their indicating procedure, rendering the perforated sheet method obsolete. Hut 6 was suddenly unable to decrypt Enigma.
438:
could be used. In May 1940, the
Germans stopped the doubly-enciphered keys. Other methods becoming ineffective, Bletchley Park started using the Herivel tip to break Luftwaffe traffic. It continued to be the main method until the
533:
ring settings with the rotors already inside the machine, the rotor position currently showing on the machine could well be the ring setting itself or be very close to it. (If that situation occurred in the above example,
1370:"... it was found that the German encipherers, after setting their Enigmas in the starting position and closing the metal lid, were selecting as the message key (Spuchschlüssel) the letters visible in the glass windows.
596:
Fortunately for the codebreakers, the pattern predicted by the Herivel tip began to manifest itself soon after on 10 May, when the Germans invaded the Netherlands and Belgium. David Rees spotted a cluster in the
776:
The Background to Newton's Principia: A Study of Newton's Dynamical Researches in the Years 1664–84 Based on Original Manuscripts from the Portsmouth Collection in the Library of the University of Cambridge
394:
intercepted messages required that the selection of rotors, the ring settings and the plugboard connections were known. At this time, the first three letters of the prelude to the message were used as an
1901:
735:
589:
The effect predicted by Herivel did not immediately show up in the Enigma traffic, however, and Bletchley Park had to continue to rely on a different technique to get into Enigma: the method of "
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After the end of the war, Herivel taught mathematics in a school for a year, but he found he could not handle the "rumbustious boys". He then joined Queen's University Belfast, where he became
1906:
1896:
1570:
672:
In 2005, researchers studying a set of Enigma-encrypted messages from World War II noted the occurrence of clustering, as predicted by the Herivel tip, in messages from August 1941.
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connections, which means that all but 6 of the 26 letters are permuted by the plugboard. The codebreakers had to use other methods to find the remaining portions of the Enigma key.
1846:
586:
in the above example. That would narrow the options for the ring settings down from 17,576 to a small set of possibilities, perhaps 6 to 30, which could be tested individually.
339:
section created to solve Army and Air Force Enigma. Herivel, then aged 21, arrived at Bletchley on 29 January 1940, and was briefed on Enigma by Alan Turing and Tony Kendrick.
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791:
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513:. (Before May 1940, the encrypted message setting was repeated, but that makes no difference to Herivel's insight.) The operator would then turn his rotors to
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For each transmitted message, the sending operator would follow a standard procedure. From September 1938, he would use an initial position to encrypt the
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position. To adjust the ring setting, the spring-loaded pin could be moved to the right to allow the ring to be turned until at the desired position.
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202:
355:
At the time that Herivel started work at Bletchley Park, Hut 6 was having only limited success with Enigma-enciphered messages, mostly from the
1866:
463:
Three rotors inside an Enigma machine. In the middle rotor, the ring setting pin can be seen with a small red indicating arrow adjacent to the
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Two Enigma rotors showing electrical contacts, stepping ratchet (on the left) and notch (on the right-hand rotor opposite letter
316:
1253:
1861:
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1597:
276:
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1306:
614:
525:). A receiving Enigma operator could use the information to recover the message setting and then decrypt the message.
434:. It was not needed at the time because the Luftwaffe was doubly-enciphering their message keys so techniques such as
418:
Herivel had an insight in February 1940 that some lazy German code clerks might give away the Enigma's ring settings (
265:
237:
195:
58:
1294:... explanation of the 'Herivel tip' is incomplete." F. H. Hinsley, E. E. Thomas, C. A. G. Simkins, C. F. G. Ransom,
1721:
This contains an account of the pre-war work on Enigma in Poland, written with the care of a professional historian.
1107:
451:
The rotors and the positioning of the ring containing the notch were changed daily. The settings were defined in a
360:
1815:"Mind of a Codebreaker", companion web site to "Decoding Nazi Secrets", originally broadcast on 9 November 1999.
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312:
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The Herivel tip suggested that there would be a cluster of entries close together, such as the cluster around
1666:
1599:
Simon Callow's Codebreaker Surprise: Thespian's university tutor was influential Codebreaker, John Herivel.
517:
and encrypt the actual message. Thus, the preamble to the message would be the unencrypted ground setting (
681:
398:
to tell the receiving operator the letters that should appear in the windows for this particular message.
188:
120:
68:
601:, and on 22 May a Luftwaffe message sent on 20 May was decoded, the first since the change in procedure.
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382:
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Hinsley et al. 1988 says the first British bombe arrived 18 March 1940. Hinsley states that "Welchman's
661:", the section responsible for solving German teleprinter ciphers by using machine methods such as the
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1841:
1836:
1356:
Enignma: How the German Machine Cipher was Broken, and How it was Read by the Allies in World War Two
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733:(April 1955), "The derivation of the equations of motion of an ideal fluid by Hamilton's principle",
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Gordon Welchman wrote that the Herivel tip was a vital part of breaking Enigma at Bletchley Park.
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The Herivel tip was used for several months until specialised codebreaking machines designed by
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Bletchley Revisited: Modest War Hero Returns to the Scene of his Greatest Code-Cracking Triumph
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in the History and Philosophy of Science. One of the students that he supervised was the actor
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295:. In retirement, he wrote an autobiographical account of his work at Bletchley Park entitled
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Newman, William (2006), "Max Newman—Mathematician, Codebreaker, and Computer Pioneer", in
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The Herivel tip was used in combination with another class of operator mistake, known as "
435:
422:) in their first message of the day. If there were several lazy clerks, the first message
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from 1924 to 1936. In 1937 he was awarded a Kitchener Scholarship to study mathematics at
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Because of the importance of his contribution, Herivel was singled out and introduced to
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264:. For a brief but critical period after May 1940, the Herivel tip in conjunction with "
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1296:
British Intelligence in the Second World War: Its Influence on Strategy and Operations
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291:. In 1956, he took a brief leave of absence from Queen's to work as a scholar at the
226:
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1019:"John Herivel obituary: One of Bletchley Park's most brilliant wartime codebreakers"
789:(December 1966), "Aspects of French Theoretical Physics in the Nineteenth Century",
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1816:
714:
685:
480:
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268:" (another class of operator error) was the main technique used to solve Enigma.
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in an intensive two-week course. Herivel later worked in administration in the "
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110:
485:, followed by the message key that had been enciphered at that setting. If the
256:. It was based on Herivel's insight into the habits of German operators of the
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240:, Herivel is remembered chiefly for the discovery of what was soon dubbed the
88:
1115:
914:(December 1965), "Newton's First Solution to the Problem of Kepler Motion",
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continuity would, at all stages, have been very serious, if not disastrous."
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152:
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30:
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873:(December 1960), "Newton's Discovery of the Law of Centrifugal Force",
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1298:, Vol 3 Part 2, Cambridge University Press, British Crown Copyright,
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16:
British science historian and World War II codebreaker (1918–2011)
1823:. (Contains similar material on the Herivel Tip to Smith, 1998).
1495:
Colossus: The Secrets of Bletchley Park's Codebreaking Computers
736:
Mathematical Proceedings of the Cambridge Philosophical Society
260:
that allowed Bletchley Park to easily deduce part of the daily
1630:
828:(November 1975), "Joseph Fourier: the man and the physicist",
497:
for example, he would then use Enigma with the rotors set to
426:
s would not be random but would have a clustering around the
1621:"WW2 Bletchley Park codebreaker John Herivel awarded plaque"
252:
and the method of establishing whether it applied using the
1254:"Bletchley Park – Remembering Herivel and the Herivel Tip"
1354:
Kozaczuk, Władysław (1984), Kasparek, Christopher (ed.),
693:
life. That was his generation; they didn't kiss and tell.
665:, as assistant to the head of the section, mathematician
649:
during a visit to Bletchley Park. He also taught Enigma
359:
Enigma network known as "Red". He was working alongside
271:
After the war, Herivel became an academic, studying the
1902:
Academics of the Dublin Institute for Advanced Studies
1358:, University Publications of America, pp. 83–84,
1497:, Oxford: Oxford University Press, pp. 176–188,
1795:, Cleobury Mortimer, Shropshire: M & M Baldwin,
1710:, Cleobury Mortimer, Shropshire: M & M Baldwin,
709:
commemorates him as 'mathematician and codebreaker'.
617:", to solve the settings and decipher the messages.
1267:the 1st of August, while the Bomb was being built.
955:The Annus Mirabilis of Sir Isaac Newton: 1666-1966
218:(29 August 1918 – 18 January 2011) was a British
1730:Codebreakers: The inside story of Bletchley Park
1393:
1341:
1278:
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690:
638:
1907:20th-century biographers from Northern Ireland
1897:Male non-fiction writers from Northern Ireland
1528:, vol. 29, no. 3, pp. 193–232,
916:The British Journal for the History of Science
792:The British Journal for the History of Science
521:), followed by the encrypted message setting (
1772:Station X: The Codebreakers of Bletchley Park
1696:
1151:
1149:
370:messages had been enciphered by the Germans'
325:Government Code and Cypher School (GC&CS)
196:
8:
1847:People educated at Methodist College Belfast
1793:The Hut Six story: Breaking the Enigma codes
953:(1970), "Newton's achievement in dynamics",
1708:Herivelismus and the German Military Enigma
984:Herivelismus and the German Military Enigma
537:would be the ring setting or close to it).
297:Herivelismus and the German Military Enigma
1852:Alumni of Sidney Sussex College, Cambridge
1667:"John Herivel: Bletchley Park codebreaker"
1337:
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385:. The main model in use in 1940 had three
248:. Herivelismus consisted of the idea, the
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1043:"Special Forces Obituaries: John Herivel"
863:Joseph Fourier: the man and the physicist
1517:Sullivan, Geoff; Weierud, Frode (2005),
1429:
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1877:Academics of Queen's University Belfast
1602:, Bletchley Park Trust, 5 November 2013
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540:Polish cryptographers used the idea at
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293:Dublin Institute for Advanced Studies
7:
1882:Fellows of All Souls College, Oxford
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653:to a party of Americans assigned to
323:. Welchman recruited Herivel to the
1732:, Oxford: Oxford University Press,
713:He published books and articles on
974:. In his retirement he published:
430:. The insight became known as the
14:
1114:, 28 January 2011, archived from
273:history and philosophy of science
1887:Historians from Northern Ireland
1234:Stripp, Alan (9 November 1999).
705:, Oxford, where Herivel died. A
561:would be recorded by entering a
317:Sidney Sussex College, Cambridge
249:
236:As a codebreaker concerned with
29:
1751:Enigma: The Battle for the Code
994:He is survived by his daughter
1728:; Stripp, Alan, eds. (1993) ,
1519:"Breaking German Army Ciphers"
1456:American 6813 Division History
1203:Cipher Machines and Cryptology
505:, which he might choose to be
443:was delivered in August 1940.
1:
1867:British historians of science
1569:Jones, Daniel (27 May 2001),
303:Recruitment to Bletchley Park
216:John William Jamieson Herivel
725:. His publications include:
447:Enigma enciphering procedure
1199:"Enigma Message Procedures"
991:He died in Oxford in 2011.
319:, where his supervisor was
238:Cryptanalysis of the Enigma
1923:
277:Queen's University Belfast
1697:Hinsley & Stripp 1993
1534:10.1080/01611190508951299
1112:Methodist College Belfast
1108:"Obituary – John Herivel"
928:10.1017/s0007087400002508
805:10.1017/S0007087400003794
757:10.1017/S0305004100030267
605:Additional key components
509:; which might encrypt to
313:Methodist College Belfast
307:John Herivel was born in
24:The Enigma cipher machine
351:Military Enigma machine.
628:", were ready for use.
331:. Welchman worked with
1747:Sebag-Montefiore, Hugh
1236:"How the Enigma Works"
962:In 1978 he retired to
710:
695:
643:
565:in the cell in column
490:
468:
415:
352:
1862:Cryptographic attacks
1857:Bletchley Park people
1394:Sebag-Montefiore 2000
1342:Sebag-Montefiore 2000
1279:Sebag-Montefiore 2000
1222:Sebag-Montefiore 2000
1141:Sebag-Montefiore 2000
700:
462:
409:
383:polyalphabetic cipher
350:
258:Enigma cipher machine
1017:(13 February 2011),
966:, where he became a
528:The ground setting (
472:message of the day.
379:rotor cipher machine
335:in the newly formed
69:Polish Cipher Bureau
1872:British biographers
1774:, Channel 4 Books,
1579:on 24 December 2012
986:, M & M Baldwin
844:1975PhT....28k..65H
826:Williams, L. Pearce
749:1955PCPS...51..344H
688:, who said of him:
381:that implemented a
1699:, pp. 149–166
1673:, 17 February 2011
1479:, pp. 160–161
1408:, pp. 104–110
1197:Rijmenants, Dirk,
723:Christiaan Huygens
711:
676:After World War II
663:Colossus computers
469:
416:
376:electro-mechanical
353:
289:Christiaan Huygens
1739:978-0-19-280132-6
1652:Plaque #31149 on
1551:on 24 August 2006
1504:978-0-19-284055-4
1491:Copeland, B. Jack
1256:. 23 January 2011
996:Josephine Herivel
972:All Souls College
865:, Clarendon Press
852:10.1063/1.3069206
647:Winston Churchill
624:, the so-called "
591:perforated sheets
220:science historian
213:
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1789:Welchman, Gordon
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951:Herivel, John W.
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1692:Enigma and Fish
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1118:on 27 July 2011
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780:Clarendon Press
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503:message setting
501:to encrypt the
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479:and send it in
449:
436:Zygalski sheets
404:
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321:Gordon Welchman
311:, and attended
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279:, particularly
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99:Zygalski sheets
59:Breaking Enigma
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1768:Smith, Michael
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1717:978-0947712464
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912:Herivel, J. W.
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883:(4): 546–553,
871:Herivel, J. W.
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787:Herivel, J. W.
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719:Joseph Fourier
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1654:Open Plaques
1653:
1647:
1635:. Retrieved
1624:
1615:
1604:, retrieved
1598:
1592:
1581:, retrieved
1577:the original
1571:
1564:
1553:, retrieved
1546:the original
1525:
1512:
1494:
1484:
1472:
1461:, retrieved
1455:
1449:
1444:, p. 78
1437:
1425:
1413:
1401:
1396:, p. 92
1389:
1377:
1369:
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1327:, p. 43
1304:0-521-351960
1295:
1286:
1274:
1265:
1258:. Retrieved
1248:
1239:
1229:
1224:, p. 81
1217:
1206:, retrieved
1202:
1192:
1180:
1175:, p. 42
1143:, p. 90
1120:, retrieved
1116:the original
1111:
1092:, p. 75
1090:Herivel 2008
1085:
1079:Herivel 2008
1074:
1069:, p. 10
1067:Herivel 2008
1062:
1051:, retrieved
1046:
1037:
1026:, retrieved
1023:The Guardian
1022:
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715:Isaac Newton
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686:Simon Callow
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428:Ringstellung
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420:Ringstellung
419:
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366:Intercepted
365:
354:
306:
296:
281:Isaac Newton
270:
246:Herivelismus
245:
241:
235:
224:World War II
215:
214:
115:
18:
1842:2011 deaths
1837:1918 births
1671:Oxford Mail
1637:29 December
1526:Cryptologia
1208:19 November
707:blue plaque
632:Recognition
622:Alan Turing
544:during the
432:Herivel tip
402:Herivel tip
368:Morse coded
333:Alan Turing
250:Herivel tip
242:Herivel tip
227:codebreaker
116:Herivel tip
111:Banburismus
1831:Categories
1688:Good, Jack
1681:References
1606:8 February
1442:Smith 1998
1325:Smith 1998
1173:Smith 1998
838:(11): 65,
667:Max Newman
599:indicators
546:Phoney War
361:David Rees
89:Cyclometer
1791:(1997) ,
1753:, Wiley,
1477:Good 1993
957:: 120–135
944:121724711
905:143523512
813:144562116
765:122422156
489:(German:
477:indicator
396:indicator
357:Luftwaffe
1821:part two
1817:Part one
1770:(1998),
1749:(2000),
1706:(2008),
1690:(1993),
1626:BBC News
1542:23474156
1260:5 August
982:(2008),
861:(1975),
817:Belfast.
774:(1965),
659:Newmanry
569:and row
542:PC Bruno
453:codebook
153:PC Bruno
1583:20 July
1555:20 July
1493:(ed.),
1463:20 July
1122:20 July
1053:20 July
1028:20 July
936:4024891
840:Bibcode
745:Bibcode
615:cillies
309:Belfast
266:cillies
167:Related
74:Doubles
1799:
1778:
1757:
1736:
1714:
1629:. UK:
1540:
1501:
1362:
1307:p. 954
1302:
1292:
968:Fellow
964:Oxford
942:
934:
903:
897:228612
895:
811:
763:
682:reader
626:bombes
493:) was
387:rotors
372:Enigma
343:Enigma
1549:(PDF)
1538:S2CID
1522:(PDF)
1002:Notes
940:S2CID
932:JSTOR
901:S2CID
893:JSTOR
809:S2CID
761:S2CID
655:Hut 6
482:clear
441:bombe
374:, an
337:Hut 6
176:Ultra
158:Cadix
146:Hut 8
141:Hut 6
136:Hut 4
131:Hut 3
126:Bombe
94:Bomba
84:Clock
79:Grill
1819:and
1797:ISBN
1776:ISBN
1755:ISBN
1734:ISBN
1712:ISBN
1639:2015
1608:2014
1585:2011
1557:2011
1499:ISBN
1465:2011
1360:ISBN
1300:ISBN
1262:2016
1240:NOVA
1210:2009
1124:2011
1055:2011
1030:2011
876:Isis
721:and
222:and
121:Crib
1695:in
1631:BBC
1530:doi
970:of
924:doi
885:doi
848:doi
801:doi
753:doi
701:75
584:GKX
559:GKX
535:GKX
530:GKX
523:LLP
519:GKX
515:RTQ
511:LLP
507:RTQ
499:GKX
495:GKX
327:at
275:at
262:key
244:or
229:at
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571:K
567:G
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190:v
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