TheCodeBreakers
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
subjected to a transposition. On this basis he began to work.
Nothing happened. The traffic was too light for him even to determine
by frequency counts whether the checkerboard key changed each day,
and without this basic information he did not dare to amalgamate the
annaabi.ee 
