Cryptographic History of Work on the German Naval Enigma


Chapter VIII


How the Hut worked.

1. This section contains a brief outline of the organization of the hut and of the work done by the various rooms. A very great deal of all this was perfectly straightforward and elaborate description and discussion would be a waste of time. I shall try to confine myself as far as possible to those things which are either of some technical interest or from which lessons for the future can be drawn. This will mean that some sections of the hut will be dealt with very cursorily - this does not in any way imply that their work was correspondingly unimportant.

2. The work of the hut was fairly sharply divided into two types (1) cryptography (to avoid misunderstanding I should perhaps say that I mean by this cryptanalysis) (2) Servicing and exploitation - the preparation of material for the cryptographers, the completion of the solution of a key from information supplied by the cryptographers and the decoding of traffic when this solution was complete.

3. Originally this division was represented by the separation of the hut into two corresponding subsections, the cryptographers constituting one of these and doing all the cryptographic work (Banburizing, building up bigram tables, and such cribbing as was not done by Naval Section) and the "Big Room" being the other. The Big Room was responsible for preparing material for the Banburists, keeping the traffic of days being worked on, testing results from the bombe, and for all routine clerical work. Later, as the work grew, it was found necessary to subdivide a good deal more. Instead of a single cryptographic section there was first a "Banburists' room" and a crib room; then we had in addition a research section and finally (when cribbing dwarfed all other technical


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