Commit df866964 authored by Florent Chehab's avatar Florent Chehab
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......@@ -292,75 +292,72 @@ Les États-Unis purent alors concentrer leurs forces aéronavales sur cet atol.
David Kahn \cite{kahn1996codebreakers} attribue les paroles suivantes à l'amiral américain Chester W. Nimitz :
Midway fut essentiellement une victoire des services de renseignements.
Midway fut essentiellement une victoire des renseignements.
L'histoire du manque de robustesse des cryptosystèmes japonais pendant la Deuxième Guerre Mondiale ne s'arrête pas ici.
Yamamoto was known to be almost compulsively punctual. He
adhered to his schedules virtually to the split second. And Lasswell was now reading almost a minute-by-minute listing of his activities on a day during which the admiral would come closer to the combat zone than he had probably ever done before! The cryptanalyzed intercept amounted to a death warrant for the highest enemy commander.
\subsubsection{the rapid cutting of Japan's lifeline}
Their failure sharpens the contrast with Allied successes. For Allied cryptanalysts—which in the Pacific meant mostly Americans—galloped like Tartars through the phalanxed ranks of a legion of Japanese cryptosystems. They ravaged and plundered with a prodigality that did not trifle with petty matters. One system, when solved, proved to be used by direction-finding teams; though this might have afforded some indirect clues to Japanese attacks, it was cast aside for richer treasure. Commander Dyer estimated that American cryptanalysts demolished 75 Japanese naval codes during the war. Among them was the four-digit code used by the marus, or Japanese merchant vessels—the s code. Presumably this was attacked after the more important combat codes had been resolved. From about 1943, it yielded information of the greatest value: the routes, timetables, and destinations of Japanese convoys. Japan's conquests consisted almost entirely of islands which could be supplied and reinforced only by sea, and Nippon itself was an island empire. American submarines therefore undertook in the Pacific what U-boats were attempting in the Atlantic, and, as with the U-boats, cryptanalysis helped them achieve their greatest successes. il A direct line led from FRUPAC to the office of Captain R. G. Voge, operations officer of the Commander, Submarines Pacific Fleet. The Japanese convoys radioed the positions where they estimated they would be as of noon on the next few days. This was to inform their own forces of their locations, but FRUPAC solved the messages, and Jasper Holmes, an ex-submariner himself, relayed them to Voge, who broadcast them to the American submarines. This fattened their kill. Vice Admiral Charles A. Lockwood, Jr., who was COMSUBPAC during most of the war, estimated that cryptanalytic information stepped up American sinkings by about one third on the trade routes to the Philippines and the Marianas. Eventually the submarine commanders received it so regularly that they complained if a convoy reached its noon position half an hour late! The pigboats accounted for nearly two thirds of Japanese merchant tonnage sunk during the war. Their torpedoing of 110 tankers from the East Indies resulted in oil shortages in the homeland that prevented the training of badly needed pilots and forced a split-up of Japan's Navy, with serious tactical results. Starvation at home caused Japan to make surrender overtures even before the islands were invaded, before the atom bombs exploded. After the war, Tojo said that the destruction of the merchant marine was one of the three factors that defeated Japan, the others being leapfrog strategy and fast carrier operations. This is why Dyer, looking back, regarded FRUPAC ' S solution of the maru code as one of its primary contributions to victory.
\subsubsection{The success of U-boats}
Lecture des codes convois
\subsubsection{La mort de Isoroku Yamamoto}
In 1941, for example, the B-Dienst read messages to convoys from the Commander in Chief, Western Approaches, that directed those convoys from the danger zones just west of the British Isles. With this intelligence, the U-boat command had no difficulty in deploying its submarines to the maximum effectiveness. Allied losses mounted steeply. In March, April, and May, U-boats sank 142 vessels, or more than one every 16 hours. In January and February of 1943, the B-Dienst mastered British naval cryptosystems so fully that it was even reading the British "U-Boat Situation Report," which was regularly broadcast to the commanders of convoys at sea, telling them the known and presumed locations of U-boats! "These 'Situation Reports' were of the greatest value to us in our efforts to determine how the enemy was able to find out about our U-boat dispositions and with what degree of accuracy he did so," wrote Admiral Donitz. The following month, March of 1943, saw the climax of the Battle of the Atlantic. And the climactic action, the greatest triumph of the U- boats, in which they very nearly severed Britain's lifeline, stemmed directly from a series of B-Dienst solutions.
Isoroku Yamamoto est le chef des armés japonaises en 1943 et c'était aussi lui le stratège derrière l'attaque de Pearl Harbor et des Midway, faisant de lui l'un des principaux ennemis public des États-Unis.
On the morning of March 16, they sighted a convoy which turned out to be HX 229, and in the next two days, 38 U-boats sent 13 ships to the bottom. Meanwhile, HX 229 overtook the slow-moving sc 122, forming a large mass of shipping in a small space of ocean. The wolf pack nipped at its edges and sank eight more vessels, making a total of 141,000 tons sunk in the three-day battle, at a cost of only a single U-boat. Donitzexulted: "It was the greatest success that we had so far scored against a convoy."
Le 13 avril un radio télégramme est transmis au front par un commandant Japonais annonçant la prochaine visite de Yamamoto. Ce message fut chiffrer dns une nouvelle version du code \texttt{JN25} que les alliés avaient cassés aussi. L'itinéraire précis de Yamamoto était alors connu et le président Rossevelt donna son accord pour abattre son avion en plein vol.
Le 18 avril 1943 au matin, un escadron américain abattu l'avion et son escorte au dessus de la Papouasie-Nouvelle-Guinée. Sa mort ne fut confirmer par les japonais que le 23 mai pour retarder la démoralisation de leurs troupes. Mais le Japon perdit un stratège exceptionnel, n'améliorant pas sa situation dans la guerre.
\subsubsection{the rapid cutting of Japan's lifeline}
\subsubsection{the defeat of the U-boats.}
Pour finir concernant les succès des cryptanalistes alliés contre le Japon, nous pouvons noter qu'ils avaient une connaissance étendus de leur cryptosystèmes et armée de télémètres pour améliorer leurs informations.
. And while Donitz' B-Dienst had its successes, the Allied
communications intelligence agencies enjoyed the advantage of access to the extremely heavy traffic of the U-boat fleet. In part, this stemmed from Donitz' insistence on maintaining tactical control of his submarines so as to concentrate them in wolf packs on the richest prizes. He was aware of the danger in all the talk, but, he contended, "The signals from the U-boats contained the information upon which was based the planning and control of those combined attacks which alone held the promise of really great success against the concentrated shipping of any enemy convoy." His encouragement of communication led to an almost complete relaxation of radio discipline. U-boats went on the air to report a toothache on board or to congratulate a friend at headquarters on a birthday. U-boat command became "the most gabby military organization in all the history of war."
Les américains avaient notamment cassés le code des navire marchands japonais servant à ravitaller les avant-postes dans le Pacifique : les trajets, destinations, horaires, etc. étaient connus. Grâce à ces informations précises, les sous-marins américains coulèrent des centaines de bateaux provoquant notamment des pénuries d'essence.
Notons cette phrase de David Kahn dans \cite{kahn1996codebreakers} :
**Chasse au U-BOAT**
Finalement, les commandants des sous-marins [américains] recevaient des informations si régulièrement qu'ils se plaignaient si un convoi arrivait à son point de rencontre avec une demi-heure de retard!
"Reduced to the simplest terms," wrote one author in a study of the Battle of the Atlantic, "the Allies won the U-boat war and Germany lost it because Donitz talked too much."
\subsubsection{La bataille de l'Atlantique}
Les succès cryptanalitiques n'étaient évidemment pas que du côté des alliés. Le \textit{B-Dienst}, le service de décryptage du haut commandement de la marine Allemande, c'est avéré très efficace dans le déchiffrement des informations sur les convois alliés chargés de ravitailler l'Angleterre. Après avoir reconstitué en grande partie les tables de chiffrements utilisés par les convois marchands alliés, le \textit{B-Dienst} fournissait les informations directement aux U-boat allemands dans l'Atlantique. Par exemple, en entre mars et mai 1941 se sont 142 navires qui ont été coulés.
\subsubsection{Rommel et l'Afrique du nord}
Au début de l'année 1943, le \textit{B-Dienst} est même parvenu à casser un code de la marine anglaise, leur donnant accès aux rapports sur la présence des U-Boat.
Dans les faits, les U-Boats opéraient en groupes ce qui résulter en des communications denses à l'intérieure de ces groupes. Les nombreux télémètres alliés pouvaient alors facilement estimé la localisation de ces derniers.
Occasionally, a single solved message produced strikingly dramatic results. During a conference at the headquarters of the Commanding General, Southwest, in 1943, Colonel Karl-Albert Miigge, commander of Fernmeldeaufklarung 7, brought Field Marshal Kesselring a British intercept that had just been cryptanalyzed. It reported that in North Africa several troop columns were caught in a traffic jam of their own making by crowding into a wadi at—and here the cryptogram was garbled so that the exact location could not be read. Kesselring called for an immediate air search; the jammed wadi was discovered while the Germans were still in conference. Kesselring promptly ordered an air attack, which wreaked considerable destruction upon the concentrated British forces.
Ce sont ces indications qui permirent de couler un nombre important de U-boat pour finalement gagner la bataille de l'Atlantique.
The American military ATTACHÉ in Cairo had much better opportunities to observe military action than his colleague in Moscow, owing to factors of distance, language, and politics, and he took full advantage of these opportunities to do his job. He was Colonel Bonner Frank Fellers, a West Pointer with a varied peacetime experience, including two years as assistant to General Douglas MacArthur. Fellers had been posted to Cairo in October, 1940. He industriously toured the battlefronts and studied the tactics and problems of desert warfare. He asked questions. He kept his eyes open. The British let him in on some of their secrets, hoping that this would improve American equipment lend- leased to Britain's desert forces, but probably withheld some because of his anti-British predilections. Fellers soaked up this great quantity of information and poured it out to Washington in voluminous and detailed reports. He discussed the British forces at the front, their duties, capabilities, and effectiveness; he told of reinforcements that were expected and supply ships that had arrived, explained morale problems, analyzed the various tactics that the British had under consideration, even reported on plans for local military operations. He carefully encoded his messages in the BLACK code and radioed them to Washington, usually addressed to MILID WASH (Mzfitary Intelligence Division, Washington). And as his transmissions flashed through the ether, listening Axis radio stations— usually at least two, so that nothing would be missed—took down every word. The intercepts were transmitted by direct wire to cryptanalysts, where they were reduced to plaintext, translated, reenciphered in a German system, and forwarded to General Erwin Rommel, commander of the Afrika Korps. He often had the messages only a few hours after Fellers had sent them.
At about the same time he lost his telescope. The United States appears to have had some suspicion of the leak earlier in the spring, when two officers came out from Washington to check on Fellers' security measures. They cleared him, and perhaps this lulled their fears until new information reached the Allies. Apparently a prisoner of war told the British of the intercepts, and the British, who had themselves broken the BLACK code and its su-perencipherment, using it to read other traffic, now began to pick up Fellers' messages within an hour after he filed them. After ten days of studying his "long, detailed, and extremely pessimistic" reports, they notified American authorities late in June of the leak and perhaps of Fellers' attitude. Fellers himself was never told of the German solutions, but was recalled to Washington, returning in
\subsubsection{Rommel et l'Afrique du nord}
En Afrique du Nord, un autre terrain de forte activité militaire lors de la Deuxième Guerre Mondiale, les cryptanalistes ont également joué un rôle crucial.
*Later in 1942 he was awarded the Distinguished Service Medal for his work as military attach, which "contributed materially to the tactical and technical development of our Armed Forces." The citation also stated that "His reports to the War Department were models of clarity and accuracy."
Tout d'abord à l'avantage de l'Allemagne.
Un espion Italien obtient la clef pour un code diplomatique américain dénommé \texttt{BLACK}, ce qui permis aux agences de l'Axe de déchiffrer les communications diplomatiques américaines mais aussi celles d'attachés militaires américains très proches des terrains militaires.
Ainsi l'attaché militaire au caire, le colonel Bonner Frank Fellers devint une source d'information détaillée sur les intentions anglaises sur ce front. Les informations interceptées par les cryptanalistes allemands étaient directement transféré au général Rommel, commandant des Afrika Korps. Ce qui lui permis d'avoir systématiquement une longueur d'avance sur les anglais jusqu'en juillet 1942, lorsqu'un nouvel attaché militaire arriva au Cair et qu'un nouveau chiffre américain entra en opération.
Privée d'une source d'une riche source d'information, Rommel perdit l'avantage, et les anglais reprirent le chemin des victoires.
Blabla sur Enigma sont on n'a pas su qu'elle avait été cryptanlysée.
Almost up to the moment of the Axis invasion, the Italian armies that had occupied Albania had exposed what Churchill picturesquely called their "naked rear" to Yugoslavia in the north. Yugoslavia had no chance against the Wehrmacht, but both Axis and Allies realized that if she struck forcefully against the rather disorganized Italians, she could win a major victory, embarrass Mussolini, delay the Axis conquest, and acquire the munitions and supplies for a large-scale guerrilla harassment of the Nazi occupiers. Thus, when two Yugoslav divisions drove southward on April 7—one from Cetinje toward Shkoder, the other from Kosowska Mitrovica toward Kukes—it was regarded as a serious business. Especially when, by April 12, the Cetinje division had shoved the Italians back to the gates of Shkoder and was pummeling them with attacks of increasing
intensity. At this juncture the Servizio Informazione Militare got an idea. It drafted two telegrams in Yugoslav military style and affixed the signature of General Dusan Simovic, head of the new government. One read: To the Cetinje divisional headquarters: Subordinate troops will suspend all offensive action and retire in the direction of Podgorica, organizing for defense. And the other: To the Kosowska Mitrovica divisional headquarters: Withdraw immediately with all subordinate troops back towards Kosowska Mitrovica. Simovic Both messages were enciphered in the Yugoslav Army system, and at 10 a.m. on April 13, an S.I.M. station, observing all Yugoslav radio regulations as to wavelength, transmission times, and subordinate stations, contacted the two divisional stations and passed the messages, both of which were receipted for. The drive toward Kukes slackened immediately. The Cetinje division, however, requested confirmation. None came.
Les faits relatés dans ce document ne sont pas les seuls connus, il y a eu d'autres comme la cryptanalise de la machine à rotor Allemande \texttt{Enigma}par les services Polonais, Anglais et Français.
En tout état de cause, la Deuxième Guerre Mondiale a été marquée par une utilisations croissantes des chiffres, par une mécanisations des procédés de chiffrement, déchiffrement et de transmission. Notons que de très nombreux cryptogrammes ont été déchiffrés par des ennemis, avec un impact crucial sur le cours de la guerre.
Only such mechanization enabled Army cryptographers to keep up with the ever- rising flood of traffic: the 23,000 codegroups a day that the 5th Army headquarters processed during its Sicily campaign strained even the machines to their limit—and by the time that army was marching on Rome, its headquarters was handling 40,000 groups a day. Traffic volume passed belief: in Hollandia, a million groups a day in November, 1944; at the Army's European Theater of Operations headquarters even before OVERLORD, 1,500,000 to 2,000,000 groups a day, or the equivalent of a shelf of 20 average books. The biggest message center of all, the War Department's in Washington, handled its peak load on August 8, 1945: nearly 9,500,000 words, the equivalent of almost one-tenth the total of French intercepts in all of World War I.
Ainsi, d'après \cite{kahn1996codebreakers}, il y eu un pic de messages transféré dans département de la Guerre à Washington le 9 août 1945, où des messages totalisants 9 500 000 mots ont transféré en un seul jour. Soit l'équivalent de un dixième de toutes les interceptions françaises pendant la première guerre mondiale.
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