Editing Cryptanalysis of the Enigma (section)

===The grill method===
The Poles now had the machine's wiring secrets, but they still needed to determine the daily keys for the cipher traffic. The Poles would examine the Enigma traffic and use the method of characteristics to determine the six permutations used for the indicator. The Poles would then use the [[grill (cryptology)|grill method]] to determine the rightmost rotor and its position. That search would be complicated by the plugboard permutation, but that permutation only swapped six pairs of letters{{snd}}not enough to disrupt the search. The grill method also determined the plugboard wiring. The grill method could also be used to determine the middle and left rotors and their setting (and those tasks were simpler because there was no plugboard), but the Poles eventually compiled a catalogue of the {{math|1=3×2×26×26={{#expr:3*2*26*26}}}} possible {{mvar|Q}} permutations (reflector and 2 leftmost rotor permutations), so they could just look up the answer.

The only remaining secret of the daily key would be the ring settings, and the Poles would attack that problem with [[brute-force attack|brute force]]. Most messages would start with the three letters "ANX" (''an'' is German for "to" and the "X" character was used as a space). It may take almost {{math|1=26×26×26={{#expr:26*26*26}}}} trials, but that was doable. Once the ring settings were found, the Poles could read the day's traffic.

The Germans made it easy for the Poles in the beginning. The rotor order only changed every quarter, so the Poles would not have to search for the rotor order. Later the Germans changed it every month, but that would not cause much trouble, either. Eventually, the Germans would change the rotor order every day, and late in the war (after Poland had been overrun) the rotor order might be changed during the day.

The Poles kept improving their techniques as the Germans kept improving their security measures.