The History of Hut Eight

(Feind in Sicht), and several paired days were broken by hand using these cribs. Naval Section were sometimes asked to confirm that a sighting had in fact taken place, and often they suggested other cribs, such as possible signatures to the messages, and these also had successes.

The first efforts to tie up WWs with the relevant Archery were made on the traffic of April 16-21 1941, and WW cribs were used successfully for getting out paired days by hand after August. A ship synoptic could carry much more detailed observation than a WW coded on WW Book, 1st Edition and as a result:

(a) It was possible to select suitable ship synoptics from the crudity of their observations: e.g. synoptics from WWs must have their wind direction divisible by 4 and their latitude and longitude in full degrees.

(b) Each letter of the seven letters of unciphered WW could be uniquely determined. The association of each Archery message with the correct ciphered WW was done by considering

Archery time and T.O.O. of possible WWs
Archery position and D/F position of possible WWs, as supplied by Naval Section 1V.
Signatures could also be cribbed if the message instructing boats to send WWs had been decoded; and if the positions of these boats were known, a given boat could usually be certainly associated with a unique piece of Archery or a unique cypher WW or both. About 2 boats sent WWs each day.

From work on WWs a new technique of getting out paired days by hand was evolved, its aim being to get over the difficulty that almost every link in the menu had an independent chance of being wrong. Routine testing of possible Stecker round a fixed menu was replaced by an attempt to find a consistent group of Stecker which would pick up suitable letters of crib and help to establish or confirm more dubious cribs in other places. If the complete Stecker could not be obtained, the partial Stecker could be used to rod out a long enigma message and the Stecker could then be completed.

Using this technique a paired day or two were broken on Rossaries on which several dummies were sent in November and December, all decode groups of which started with Y or Z.

B-bars and short E-bars were not used much (except occasionally for getting the Ringstellung). When Augsburg was introduced on October 5th efforts were made to rod out as many settings as possible using the acknowledgement cribs which were available when the day was broken.


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