589:
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
401:
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.
418:
467:
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.
709:
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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,
471:
359:
42:
1292:, 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."
374:, 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.
588:
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|
466:
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
1277:
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
567:
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
482:
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
404:
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
543:
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
703:
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
400:
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
651:
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
620:
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
827:
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,
604:", 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.
449:
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
544:
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,
1381:"... 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.
607:
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
787:
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
405:
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
1912:
746:
600:
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 "
691:
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
1917:
1907:
1581:
683:
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.
1857:
597:
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.
350:
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.
1887:
1862:
802:
1892:
524:. (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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1053:
478:
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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213:
366:
At the time that Herivel started work at Bletchley Park, Hut 6 was having only limited success with Enigma-enciphered messages, mostly from the
1877:
474:
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
335:
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1513:
303:
417:
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Two Enigma rotors showing electrical contacts, stepping ratchet (on the left) and notch (on the right-hand rotor opposite letter
327:
1264:
1872:
1867:
1608:
287:
1882:
1317:
625:
536:). A receiving Enigma operator could use the information to recover the message setting and then decrypt the message.
445:. It was not needed at the time because the Luftwaffe was doubly-enciphering their message keys so techniques such as
429:
Herivel had an insight in February 1940 that some lazy German code clerks might give away the Enigma's ring settings (
276:
248:
206:
69:
1305:... explanation of the 'Herivel tip' is incomplete." F. H. Hinsley, E. E. Thomas, C. A. G. Simkins, C. F. G. Ransom,
1732:
This contains an account of the pre-war work on Enigma in Poland, written with the care of a professional historian.
1118:
462:
The rotors and the positioning of the ring containing the notch were changed daily. The settings were defined in a
371:
1826:"Mind of a Codebreaker", companion web site to "Decoding Nazi Secrets", originally broadcast on 9 November 1999.
982:
323:
1902:
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The Herivel tip suggested that there would be a cluster of entries close together, such as the cluster around
1677:
1610:
Simon Callow's Codebreaker Surprise: Thespian's university tutor was influential Codebreaker, John Herivel.
528:
and encrypt the actual message. Thus, the preamble to the message would be the unencrypted ground setting (
692:
409:
to tell the receiving operator the letters that should appear in the windows for this particular message.
199:
131:
79:
612:, and on 22 May a Luftwaffe message sent on 20 May was decoded, the first since the change in procedure.
1757:
393:
1301:
Hinsley et al. 1988 says the first British bombe arrived 18 March 1940. Hinsley states that "Welchman's
672:", the section responsible for solving German teleprinter ciphers by using machine methods such as the
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1852:
1847:
1367:
Enignma: How the German Machine Cipher was Broken, and How it was Read by the Allies in World War Two
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755:
744:(April 1955), "The derivation of the equations of motion of an ideal fluid by Hamilton's principle",
397:
186:
104:
94:
84:
59:
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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
1583:
Bletchley Revisited: Modest War Hero Returns to the Scene of his Greatest Code-Cracking Triumph
1246:
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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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306:. In retirement, he wrote an autobiographical account of his work at Bletchley Park entitled
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763:
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386:
1799:
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Newman, William (2006), "Max Newman—Mathematician, Codebreaker, and Computer Pioneer", in
790:
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The Herivel tip was used in combination with another class of operator mistake, known as "
446:
433:) in their first message of the day. If there were several lazy clerks, the first message
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326:
from 1924 to 1936. In 1937 he was awarded a Kitchener Scholarship to study mathematics at
109:
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Because of the importance of his contribution, Herivel was singled out and introduced to
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275:. For a brief but critical period after May 1940, the Herivel tip in conjunction with "
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49:
1307:
British Intelligence in the Second World War: Its Influence on Strategy and Operations
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841:
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302:. In 1956, he took a brief leave of absence from Queen's to work as a scholar at the
237:
1831:
1552:
1030:"John Herivel obituary: One of Bletchley Park's most brilliant wartime codebreakers"
800:(December 1966), "Aspects of French Theoretical Physics in the Nineteenth Century",
358:
1827:
725:
696:
491:
291:
234:
279:" (another class of operator error) was the main technique used to solve Enigma.
717:
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in an intensive two-week course. Herivel later worked in administration in the "
632:
343:
121:
496:, followed by the message key that had been enciphered at that setting. If the
267:. It was based on Herivel's insight into the habits of German operators of the
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767:
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251:, Herivel is remembered chiefly for the discovery of what was soon dubbed the
99:
1126:
925:(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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17:
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163:
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41:
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884:(December 1960), "Newton's Discovery of the Law of Centrifugal Force",
319:
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1309:, Vol 3 Part 2, Cambridge University Press, British Crown Copyright,
978:
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27:
British science historian and World War II codebreaker (1918–2011)
1834:. (Contains similar material on the Herivel Tip to Smith, 1998).
1506:
Colossus: The Secrets of Bletchley Park's Codebreaking Computers
747:
Mathematical Proceedings of the Cambridge Philosophical Society
271:
that allowed Bletchley Park to easily deduce part of the daily
1641:
839:(November 1975), "Joseph Fourier: the man and the physicist",
508:
for example, he would then use Enigma with the rotors set to
437:
s would not be random but would have a clustering around the
1632:"WW2 Bletchley Park codebreaker John Herivel awarded plaque"
263:
and the method of establishing whether it applied using the
1265:"Bletchley Park – Remembering Herivel and the Herivel Tip"
1365:
Kozaczuk, Władysław (1984), Kasparek, Christopher (ed.),
704:
life. That was his generation; they didn't kiss and tell.
676:, as assistant to the head of the section, mathematician
660:
during a visit to Bletchley Park. He also taught Enigma
370:
Enigma network known as "Red". He was working alongside
282:
After the war, Herivel became an academic, studying the
1913:
Academics of the Dublin Institute for Advanced Studies
1369:, University Publications of America, pp. 83–84,
1508:, Oxford: Oxford University Press, pp. 176–188,
1806:, Cleobury Mortimer, Shropshire: M & M Baldwin,
1721:, Cleobury Mortimer, Shropshire: M & M Baldwin,
720:
commemorates him as 'mathematician and codebreaker'.
628:", to solve the settings and decipher the messages.
1278:the 1st of August, while the Bomb was being built.
966:The Annus Mirabilis of Sir Isaac Newton: 1666-1966
229:(29 August 1918 – 18 January 2011) was a British
1741:Codebreakers: The inside story of Bletchley Park
1404:
1352:
1289:
1232:
1151:
701:
649:
1918:20th-century biographers from Northern Ireland
1908:Male non-fiction writers from Northern Ireland
1539:, vol. 29, no. 3, pp. 193–232,
927:The British Journal for the History of Science
803:The British Journal for the History of Science
532:), followed by the encrypted message setting (
1783:Station X: The Codebreakers of Bletchley Park
1707:
1162:
1160:
381:messages had been enciphered by the Germans'
336:Government Code and Cypher School (GC&CS)
207:
8:
1858:People educated at Methodist College Belfast
1804:The Hut Six story: Breaking the Enigma codes
964:(1970), "Newton's achievement in dynamics",
1719:Herivelismus and the German Military Enigma
995:Herivelismus and the German Military Enigma
548:would be the ring setting or close to it).
308:Herivelismus and the German Military Enigma
1863:Alumni of Sidney Sussex College, Cambridge
1678:"John Herivel: Bletchley Park codebreaker"
1348:
1346:
1344:
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396:. The main model in use in 1940 had three
259:. Herivelismus consisted of the idea, the
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31:
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1109:
1054:"Special Forces Obituaries: John Herivel"
874:Joseph Fourier: the man and the physicist
1528:Sullivan, Geoff; Weierud, Frode (2005),
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1392:
1195:
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1888:Academics of Queen's University Belfast
1613:, Bletchley Park Trust, 5 November 2013
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551:Polish cryptographers used the idea at
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34:
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304:Dublin Institute for Advanced Studies
7:
1893:Fellows of All Souls College, Oxford
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664:to a party of Americans assigned to
334:. Welchman recruited Herivel to the
1743:, Oxford: Oxford University Press,
724:He published books and articles on
985:. In his retirement he published:
441:. The insight became known as the
25:
1125:, 28 January 2011, archived from
284:history and philosophy of science
1898:Historians from Northern Ireland
1245:Stripp, Alan (9 November 1999).
716:, Oxford, where Herivel died. A
572:would be recorded by entering a
328:Sidney Sussex College, Cambridge
260:
247:As a codebreaker concerned with
40:
1762:Enigma: The Battle for the Code
1005:He is survived by his daughter
1739:; Stripp, Alan, eds. (1993) ,
1530:"Breaking German Army Ciphers"
1467:American 6813 Division History
1214:Cipher Machines and Cryptology
516:, which he might choose to be
454:was delivered in August 1940.
1:
1878:British historians of science
1580:Jones, Daniel (27 May 2001),
314:Recruitment to Bletchley Park
227:John William Jamieson Herivel
736:. His publications include:
458:Enigma enciphering procedure
1210:"Enigma Message Procedures"
1002:He died in Oxford in 2011.
330:, where his supervisor was
249:Cryptanalysis of the Enigma
1934:
288:Queen's University Belfast
1708:Hinsley & Stripp 1993
1545:10.1080/01611190508951299
1123:Methodist College Belfast
1119:"Obituary – John Herivel"
939:10.1017/s0007087400002508
816:10.1017/S0007087400003794
768:10.1017/S0305004100030267
616:Additional key components
520:; which might encrypt to
324:Methodist College Belfast
318:John Herivel was born in
35:The Enigma cipher machine
362:Military Enigma machine.
639:", were ready for use.
342:. Welchman worked with
1758:Sebag-Montefiore, Hugh
1247:"How the Enigma Works"
973:In 1978 he retired to
721:
706:
654:
576:in the cell in column
501:
479:
426:
363:
1873:Cryptographic attacks
1868:Bletchley Park people
1405:Sebag-Montefiore 2000
1353:Sebag-Montefiore 2000
1290:Sebag-Montefiore 2000
1233:Sebag-Montefiore 2000
1152:Sebag-Montefiore 2000
711:
473:
420:
394:polyalphabetic cipher
361:
269:Enigma cipher machine
1028:(13 February 2011),
977:, where he became a
539:The ground setting (
483:message of the day.
390:rotor cipher machine
346:in the newly formed
80:Polish Cipher Bureau
1883:British biographers
1785:, Channel 4 Books,
1590:on 24 December 2012
997:, M & M Baldwin
855:1975PhT....28k..65H
837:Williams, L. Pearce
760:1955PCPS...51..344H
699:, who said of him:
392:that implemented a
1710:, pp. 149–166
1684:, 17 February 2011
1490:, pp. 160–161
1419:, pp. 104–110
1208:Rijmenants, Dirk,
734:Christiaan Huygens
722:
687:After World War II
674:Colossus computers
480:
427:
387:electro-mechanical
364:
300:Christiaan Huygens
1750:978-0-19-280132-6
1663:Plaque #31149 on
1562:on 24 August 2006
1515:978-0-19-284055-4
1502:Copeland, B. Jack
1267:. 23 January 2011
1007:Josephine Herivel
983:All Souls College
876:, Clarendon Press
863:10.1063/1.3069206
658:Winston Churchill
635:, the so-called "
602:perforated sheets
231:science historian
224:
223:
16:(Redirected from
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1800:Welchman, Gordon
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962:Herivel, John W.
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1703:Enigma and Fish
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1129:on 27 July 2011
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791:Clarendon Press
781:
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689:
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618:
591:
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565:
514:message setting
512:to encrypt the
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490:and send it in
460:
447:Zygalski sheets
415:
356:
332:Gordon Welchman
322:, and attended
316:
290:, particularly
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191:
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110:Zygalski sheets
70:Breaking Enigma
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28:
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11:
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1779:Smith, Michael
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1728:978-0947712464
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894:(4): 546–553,
882:Herivel, J. W.
878:
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810:(2): 109–132,
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742:Herivel, J. W.
730:Joseph Fourier
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563:Herivel square
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265:Herivel square
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1665:Open Plaques
1664:
1658:
1646:. Retrieved
1635:
1626:
1615:, retrieved
1609:
1603:
1592:, retrieved
1588:the original
1582:
1575:
1564:, retrieved
1557:the original
1536:
1523:
1505:
1495:
1483:
1472:, retrieved
1466:
1460:
1455:, p. 78
1448:
1436:
1424:
1412:
1407:, p. 92
1400:
1388:
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1338:, p. 43
1315:0-521-351960
1306:
1297:
1285:
1276:
1269:. Retrieved
1259:
1250:
1240:
1235:, p. 81
1228:
1217:, retrieved
1213:
1203:
1191:
1186:, p. 42
1154:, p. 90
1131:, retrieved
1127:the original
1122:
1103:, p. 75
1101:Herivel 2008
1096:
1090:Herivel 2008
1085:
1080:, p. 10
1078:Herivel 2008
1073:
1062:, retrieved
1057:
1048:
1037:, retrieved
1034:The Guardian
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439:Ringstellung
438:
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431:Ringstellung
430:
428:
422:
403:
377:Intercepted
376:
365:
317:
307:
292:Isaac Newton
281:
257:Herivelismus
256:
252:
246:
235:World War II
226:
225:
126:
29:
1853:2011 deaths
1848:1918 births
1682:Oxford Mail
1648:29 December
1537:Cryptologia
1219:19 November
718:blue plaque
643:Recognition
633:Alan Turing
555:during the
443:Herivel tip
413:Herivel tip
379:Morse coded
344:Alan Turing
261:Herivel tip
253:Herivel tip
238:codebreaker
127:Herivel tip
122:Banburismus
18:Herivel tip
1842:Categories
1699:Good, Jack
1692:References
1617:8 February
1453:Smith 1998
1336:Smith 1998
1184:Smith 1998
849:(11): 65,
678:Max Newman
610:indicators
557:Phoney War
372:David Rees
100:Cyclometer
1802:(1997) ,
1764:, Wiley,
1488:Good 1993
968:: 120–135
955:121724711
916:143523512
824:144562116
776:122422156
500:(German:
488:indicator
407:indicator
368:Luftwaffe
1832:part two
1828:Part one
1781:(1998),
1760:(2000),
1717:(2008),
1701:(1993),
1637:BBC News
1553:23474156
1271:5 August
993:(2008),
872:(1975),
828:Belfast.
785:(1965),
670:Newmanry
580:and row
553:PC Bruno
464:codebook
164:PC Bruno
1594:20 July
1566:20 July
1504:(ed.),
1474:20 July
1133:20 July
1064:20 July
1039:20 July
947:4024891
851:Bibcode
756:Bibcode
626:cillies
320:Belfast
277:cillies
178:Related
85:Doubles
1810:
1789:
1768:
1747:
1725:
1640:. UK:
1551:
1512:
1373:
1318:p. 954
1313:
1303:
979:Fellow
975:Oxford
953:
945:
914:
908:228612
906:
822:
774:
693:reader
637:bombes
504:) was
398:rotors
383:Enigma
354:Enigma
1560:(PDF)
1549:S2CID
1533:(PDF)
1013:Notes
951:S2CID
943:JSTOR
912:S2CID
904:JSTOR
820:S2CID
772:S2CID
666:Hut 6
493:clear
452:bombe
385:, an
348:Hut 6
187:Ultra
169:Cadix
157:Hut 8
152:Hut 6
147:Hut 4
142:Hut 3
137:Bombe
105:Bomba
95:Clock
90:Grill
1830:and
1808:ISBN
1787:ISBN
1766:ISBN
1745:ISBN
1723:ISBN
1650:2015
1619:2014
1596:2011
1568:2011
1510:ISBN
1476:2011
1371:ISBN
1311:ISBN
1273:2016
1251:NOVA
1221:2009
1135:2011
1066:2011
1041:2011
887:Isis
732:and
233:and
132:Crib
1706:in
1642:BBC
1541:doi
981:of
935:doi
896:doi
859:doi
812:doi
764:doi
712:75
595:GKX
570:GKX
546:GKX
541:GKX
534:LLP
530:GKX
526:RTQ
522:LLP
518:RTQ
510:GKX
506:GKX
338:at
286:at
273:key
255:or
240:at
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