Editing Cryptanalysis of the Enigma (section)

===Polish ''bomba''===
{{Main|Bomba (cryptography)}}
After [[Marian Rejewski|Rejewski's]] characteristics method became useless, he invented an electro-mechanical device that was dubbed the [[bomba (cryptography)|''bomba kryptologiczna'']], 'cryptologic bomb'. Each machine contained six sets of Enigma rotors for the six positions of the repeated three-letter key. Like the Zygalski sheet method, the ''bomba'' relied on the occurrence of ''females'', but required only three instead of about ten for the sheet method. Six ''bomby''<ref>''Bomby'' is the plural of ''bomba''.</ref> were constructed, one for each of the then possible ''wheel orders''. Each ''bomba'' conducted an exhaustive (brute-force) analysis of the 17,576<ref>17,576=26<sup>3</sup>, since Enigma used 26 letters on each of 3 rotors.</ref> possible message keys.

Rejewski has written about the device: {{blockquote|The bomb method, invented in the autumn of 1938, consisted largely in the automation and acceleration of the process of reconstructing daily keys. Each cryptologic bomb (six were built in Warsaw for the Biuro Szyfrów Cipher Bureau before September 1939) essentially constituted an electrically powered aggregate of six Enigmas. It took the place of about one hundred workers and shortened the time for obtaining a key to about two hours.<ref>{{Harvnb|Rejewski|1984e|p=290}}</ref>}}

The cipher message transmitted the ''Grundstellung'' in the clear, so when a ''bomba'' found a match, it revealed the rotor order, the rotor positions, and the ring settings. The only remaining secret was the plugboard permutation.<!-- apparently easy to solve, but who said so? Alexander? -->