Cryptanalysis of the Enigma by the letters on the top row of the Enigma keyboard. So, "continuation of message sent at 2330" was represented as "FORTYWEEPYYWEEPY". "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. Foremost amongst the knowledge needed for identifying cribs was the text of previous decrypts. Bletchley Park maintained detailed indexes of message preambles, of every person, of every ship, of every unit, of every weapon, of every technical term and of repeated
Enigma machine keyboard and lampboard contained 29 letters—A-Z, Ä, Ö and Ü—which were arranged alphabetically, as opposed to the QWERTZUI ordering. The rotors had 28 contacts, with the letter "X" wired to bypass the rotors unencrypted. Three rotors were chosen from a set of five and the reflector could be inserted in one of four different positions, denoted α, β, γ and δ. The machine was revised slightly in July 1933. By 15 July 1928, the German Army ("Reichswehr") had introduced their own exclusive version of the Enigma machine; the "Enigma G". The "Abwehr" used the "Enigma G" (the "Abwehr" Enigma). This