TheCodeBreakers
had reportedly been chosen from among many candidates by a
conference of German cipher specialists, constituted an element in this
overall security, as did the new Schliis-selheft. The Allies bent every effort
and tapped every source of information to find out the time and place of
the real assault. But one of their most flowing founts—cryptanalysis —
appeared to have dried up.
When the first ADFGX messages got to Georges Painvin,
the best cryptanalyst in the Bureau du Chiffre, he stared at them, ran
a hand through his thick black hair with an air of perplexity, and then
set to work. The presence of only five letters immediately suggested a
checkerboard. Without much hope, he tried the messages as simple
monoalpha-betics; the tests were, as he had expected, negative. He
discarded a polyalphabetic checkerboard as too cumbersome, and was
left with the hypothesis that the checkerboard substitution had been
annaabi.ee 
