The History of Hut Eight

With an increased knowledge of the operational use of B-bars (albeit in a different area), an effort was made to crib Shark B-bars in September when traffic was heavy. On Sept. 26th a level start of 5 Shark B-bars was solved in depth with such plausibility that a menu from the crib was run for all Wheel Orders as a 4 wheel job on the assumption that the Ringstellung on the Zusatzwalze had been moved. It went down.


Between the introduction of the WW book on January 20 and February 1st there were 9 WWs consisting of a trigram followed by 3 4-letter groups. At first it was thought that a trigram indicator system (similar to that used for B-bars) had been introduced, though the trigrams obeyed no simple addition law, but it was always borne in mind that the 1st letter of the 1st 4-letter group might still be the indicator, and that the trigram might fulfill some other purpose.

Among the 9 WWs available in January were two which D/Fd in the same area, whose cypher texts read


the signature WF was rodded against both and 26 possible decodes for each obtained. Two of these were identical; decode of (a) at MDG = decode of (b) at FBQ, in every place including the first letter. This was the first certain decode, which had no Archery and produced contradictory evidence on the indicator problem.

The second decode (for which there was no WW but for which there was Archery) came from a long enigma message saying.

"LP from Westgruppe, Kurzwetter 0230/20: VTRWMNEEO".

This could be shown not to include the signature and implied only 9 letters of decode text.

The third decode came from a WW on 28th. The crib consisted of an alternative signature WG or OB and Archery was available, giving the same latitude as the Archery of the 2nd decode.

The cribs(-) V.. .... ..WG
(-) V.. .... ..OB

were rodded and a latter gave a solution with decode: (B) VKB JONB GOOB, in which the difference between the letter following V in the second and third decodes equalled the difference of the longitude in their Archeries.

A second WW on the 28th was rodded out using as crib the signature which had previously failed (WG) and position calcu-


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