[ISN] Key to breaking Nazi code was in the patent office

From: InfoSec News (isnat_private)
Date: Thu Apr 19 2001 - 23:51:50 PDT

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    By Michael Smith
    Friday 20 April 2001
    BRITAIN'S wartime codebreakers could have cracked the German Enigma
    cipher machine much earlier if they had followed a diagram for the
    commercial version lodged with the British Patent Office in the
    mid-1920s, documents released to the Public Record Office show.
    But the codebreakers did not believe that the German army would have
    been so stupid as to use the same simple wiring system as the widely
    available commercial machine for their military equivalents. The Code
    and Cypher School, commonly known by its wartime home at Bletchley
    Park, was fully aware of how the commercial machine worked in the
    Chiffriermaschinen Aktiengesellschaft, the German company that
    manufactured it, had offered the British Government commercial Enigma
    machines at a price of $190 each in June 1924. Britain declined to
    take up the offer, waiting for the Germans to register it with the
    British Patent Office.
    Then they obtained the description of how it worked from the patent
    officials, including detailed plans of the make-up of the commercial
    machine.The files show that, contrary to what had previously been
    thought, British codebreakers were working on the Enigma machine
    during the 1920s and 1930s.
    But they did not manage to break the military variant until early 1940
    after gaining vital help from the Poles. The Enigma machine looked
    like a typewriter. Pressing the keys sent an electrical impulse
    through a series of circuits wired through rotors that moved with each
    tap of the key, constantly varying the cipher.
    British codebreakers had made a good deal of progress in breaking the
    military version but were held up because they could not work out the
    order in which the typewriter keys were wired into the internal
    circuits. "The Germans weren't idiots," said Peter Twinn, one of those
    who broke Enigma. "When they had a perfect opportunity to introduce a
    safeguard to their machine by jumbling it up, that would be a sensible
    thing to do."
    It was not until July 1939, when they met their Polish equivalents who
    had broken early versions of the machine, that they found out that it
    was wired alphabetically, A to the first contact, B to the second
    contact and so on. This was the same as in the diagram attached to the
    patent application but was so obvious that the codebreakers never even
    considered it as a possibility.
    Six months later, codebreakers made their first break into Enigma,
    something they could have done far earlier if they had only tried the
    alphabetical system in the patent application."It was such an obvious
    thing to do, really a silly thing to do, that nobody ever thought it
    worthwhile trying it," said Mr Twinn.
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