Door Anoniem: Door Anoniem: Even ter intentie: er bestaat geen onkraakbare versleuteling. De Duitsers dachten ook dat ENIGMA onkraakbaar was, maar verloren daarmee juist de oorlog.
Als de Duitsers het woord 'heil hitler' niet hadden gebruikt was deze misschien ook niet gekraakt.
Het spreekwoord 'de ketting wordt bepaald door de zwakste schakel' geld ook bij beveiliging.
https://www.pi4zwn.nl/verslag-lezing-enigma-operatie-bletchley-park/ Dat verslag is net wat te populair . Uit wat serieuzere bronnen heb ik nooit gelezen dat juist 'heil hitler' de meest nuttige 'crib' was (of uberhaupt voorkwam) .
crib = stukje known plaintext .
https://en.wikipedia.org/wiki/Cryptanalysis_of_the_EnigmaDe typische cribs waren juist het soort tekst dat je verwacht in routine verslagen met een standaard structuur.
'wetter vorhersage' (weersverwachting) - verzonden op vaste tijd.
"nothing to report" .
Soms werden cribs gemaakt - een bericht via een dubbel-agent verstuurd, dan dan doorgestuurd werd door de Duitsers met Enigma codering. Mijnen plaatsen op locaties die in het Duitse kaartenraster 'nuttige' coordinaten hebben.
Het is te kort door de bocht en te popi-jopi om nu juist het decoderen op te hangen aan 'hadden ze maar geen heil hitler moeten schrijven' .
Met de natte vinger - ik denk dat de Enigma niet veilig te gebruiken was voor enig volume aan berichten met onvermijdelijk lekkende of chosen plaintext en berichtstructuur zoals in een leger organisatie gebruikelijk is.
Self-followup .
Omdat de wiki URL een erg uitgebreide pagina is, hieronder de quote omtrent 'cribs' .
Dit hele verhaal is dan versimpeld tot ' ze schreven altijd heil hitler en daarom was het te kraken' .
Cribs were fundamental to the British approach to solving Enigma keys, but guessing the plaintext for a message was a highly skilled business. So in 1940 Stuart Milner-Barry set up a special Crib Room in Hut 8.[108][109]
Foremost among the knowledge needed for identifying cribs was the text of previous decrypts. Bletchley Park maintained detailed indexes[110] of message preambles, of every person, of every ship, of every unit, of every weapon, of every technical term, and of repeated phrases such as forms of address and other German military jargon.[111] For each message the traffic analysis recorded the radio frequency, the date and time of intercept, and the preamble—which contained the network-identifying discriminant, the time of origin of the message, the callsign of the originating and receiving stations, and the indicator setting. This allowed cross referencing of a new message with a previous one.[112] Thus, as Derek Taunt, another Cambridge mathematician-cryptanalyst wrote, the truism that "nothing succeeds like success" is particularly apposite here.[99]
Stereotypical messages included Keine besonderen Ereignisse (literally, "no special occurrences"—perhaps better translated as "nothing to report"),[113] An die Gruppe ("to the group")[114] and a number that came from weather stations such as weub null seqs null null ("weather survey 0600"). This was actually rendered as WEUBYYNULLSEQSNULLNULL. The word WEUB being short for Wetterübersicht, YY was used as a separator, and SEQS was common abbreviation of sechs (German for "six").[115] As another example, Field Marshal Erwin Rommel's Quartermaster started all of his messages to his commander with the same formal introduction.[116]
With a combination of probable plaintext fragment and the fact that no letter could be enciphered as itself, a corresponding ciphertext fragment could often be tested by trying every possible alignment of the crib against the ciphertext, a procedure known as crib-dragging. This, however, was only one aspect of the processes of solving a key. Derek Taunt has written that the three cardinal personal qualities that were in demand for cryptanalysis were (1) a creative imagination, (2) a well-developed critical faculty, and (3) a habit of meticulousness.[117] Skill at solving crossword puzzles was famously tested in recruiting some cryptanalysts. This was useful in working out plugboard settings when a possible solution was being examined. For example, if the crib was the word WETTER (German for "weather") and a possible decrypt before the plugboard settings had been discovered, was TEWWER, it is easy to see that T with W are stecker partners.[118] These examples, although illustrative of the principles, greatly over-simplify the cryptanalysts' tasks.
A fruitful source of cribs was re-encipherments of messages that had previously been decrypted either from a lower-level manual cipher or from another Enigma network.[119] This was called a kiss and happened particularly with German naval messages being sent in the dockyard cipher and repeated verbatim in an Enigma cipher. One German agent in Britain, Nathalie Sergueiew, code named Treasure, who had been 'turned' to work for the Allies, was very verbose in her messages back to Germany, which were then re-transmitted on the Abwehr Enigma network. She was kept going by MI5 because this provided long cribs, not because of her usefulness as an agent to feed incorrect information to the Abwehr.[120]
Occasionally, when there was a particularly urgent need to solve German naval Enigma keys, such as when an Arctic convoy was about to depart, mines would be laid by the RAF in a defined position, whose grid reference in the German naval system did not contain any of the words (such as sechs or sieben) for which abbreviations or alternatives were sometimes used.[121] The warning message about the mines and then the "all clear" message, would be transmitted both using the dockyard cipher and the U-boat Enigma network. This process of planting a crib was called gardening.[122]
Although cillies were not actually cribs, the chit-chat in clear that Enigma operators indulged in among themselves often gave a clue as to the cillies that they might generate.[123]
When captured German Enigma operators revealed that they had been instructed to encipher numbers by spelling them out rather than using the top row of the keyboard, Alan Turing reviewed decrypted messages and determined that the word eins ("one") appeared in 90% of messages.[citation needed] Turing automated the crib process, creating the Eins Catalogue, which assumed that eins was encoded at all positions in the plaintext. The catalogue included every possible rotor position for EINS with that day's wheel order and plugboard connections.[124]