TheCodeBreakers
Quiet possibly the finest feat of cryptanalysis performed by the
Swedes, and the most far-reaching, was Arne Beurl-ing's solution of the
German Siemens machine. Since German messages passed over Swedish
wires just as German soldiers passed over Swedish rails, both the
Wehrmacht in Norway and the German embassy in Stockholm took
advantage of the machine's on-line capabilities to wire messages directly
to Berlin. The German Foreign Office called the machine the
Geheimschreiber ("secret writer"). The teleprinters in the Swedish
cryptanalytic bureau rapped out the German correspondence, and it was
given to Beurling for an attempt at solution.
He observed at once that the ciphertext consisted of the 26 letters and
six digits, a total of 32 characters, or 2B. This suggested a cipher based
on a teletypewriter to him, since he knew that teletypewriters used a five-
hole punched tape. That was about all he knew, though, and he had to
annaabi.ee 
