Cryptographic History of Work on the German Naval Enigma

10. This problem was put up to Squadrom Leader Jones, the head of the "Bombe Hut" To whom we were already heavily indebted for the magnificent work he and his staff had put in on the maintenance and repair of the bombes. In amazingly quick time he produced the answer, Fillibuster. Fillibuster (why so named I cannot imagine) was a glorified "Jones Dudbuster"; where the latter tested 9 cribs at a time (or one crib on nine messages) the new machine would simultaneously test 4 cribs on each of 80 messages. A large number of messages in the traffic were always urgent and these usually began with an encyphered priority word, KRKR, BINE, HUKE and WESPE being the commonest. Fillibuster would get all these messages out reasonably quickly and this would have solved the problem.

11. In fact (a slight anticlimax) the end of the war arrived just before the change of bigram tables, but a somewhat analogous problem, which would otherwise probably have defeated us, arose in April 1945 (the Plaice multigrundstellung problem) and was solved by Fillibuster.

12. I have inserted this rather long semitechnical digression because it is interesting to see how a fundamentally very subsidiary problem (breaking out a message when everything but its starting position is known) can (a) present serious practical difficulties (b) be tackled in a large number of totally different ways. It is also a problem coming up in more than one connection; besides the bigram table change there are the problems (1) of finding Offizier settings (2) of getting out a "dud" message, one with missing or corrupt indicator groups.

13. During November, Bonito revived - re-encoding from Dolphin - and in turn revived Porpoise, a Bonito/Porpoise R.E. being discovered. Bonito celebrated its revival by giving birth to Bounce, an eccentric offspring in that it was - and remained - a 3 wheel key, besides having various other peculiar and rather old fashioned characteristics. It carried North Italian traffic generally similar to that on Bonito.


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