Solving Enigma's Secrets: The Official History of Bletchley Park's Hut 6 by John Jackson

Author:John Jackson
Language: eng
Format: mobi
Tags: Biography, History
ISBN: 9780955716430
Published: 2014-08-29T22:00:00+00:00

Army keys

Wheel orders: From a general point of view there is little to report in this line except that, as time went on, clashing wheel orders became rare until, in March 1945, it became reasonable to give a preference for the 32 non-clashing wheel orders on nearly all Army keys. There were, however, a few oddities. One such was that the railway key, Culverin, only used wheels 1, 2 and 3 like Tricycle of old. Another peculiarity was found on Ibis of December. Out of 15 days broken, 14 had a 3 in the wheelorder, clearly not a fortuitous occurrence. There were also a number of wheelorder repeats, namely, days 1 and 12; 5 and 15; 7 and 19; 8, 20 and 30. This suggested that the compiler of the key had split the month into three sections and used roughly the same wheelorders in each period, but we were unable to test this hypothesis further. In no other month did Ibis show any comparable peculiarity.

Ringstellung: The old Army ringstellung rule was not seen after January 1944 and no new rule took its place. The increase in stuttering ringstellung has been noted elsewhere. Apart from this, we have to note only a few oddities – for instance, from February to April Wagtail, the practice key of Wehrkreis VIII had a ringstellung which only differed from that of Falcon I by being two less on the first wheel. (The rest of the key was the same as Falcon.) Again, July 1944 Nightjar repeated its ringstellung in a peculiar way. Days 11-19 repeated the ringstellung of 1, 3-10 (with an alteration of a letter in a few cases) and most of the days 20-31 had for ringstellung some permutation of a ringstellung previously used.

Stecker: Here we have to record a few cases of partial repeats within the same month and also a new form of stecker pattern. The partial repeats occurred on Nightjar of July 1944 (already mentioned under ringstellung) and Falcon I of January 1945. On Nightjar there was a repeat of sets of self-stecker at irregular intervals – out of 29 days broken only 14 self-stecker sets were used, some as often as three times, e.g.,

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