The History of Hut Eight

i. Reencodements from Hand Cyphers:

The two main sources of reencodements from hand cyphers were Werftschuessel and R.H.V. Werftschussel was used by small ships in the German Home Waters area, mostly in the Baltic: it was read continuously from early 1941 to February 1945 when it was abandoned as of being of little further value. R.H.V., the reserve hand cypher of the German Navy, was being used, apart from its function as an emergency cypher, by a number of small ships in the Norwegian area when it was first captured in December 1941. Presumably owing to the completion of the distribution of the machine, its use gradually declined and there has been little traffic since the end of 1943.

Reencodements from these cyphers were of the type one would expect - messages of significance to great and small alike: weather messages, gale warnings, aircraft reports, mine warnings, wreck warnings etc. Given the R.H.V. or Werft version of the signal, it was not normally difficult to find its enigma pair. Habits about relative time of origin varied somewhat from area to area but were fairly consistent in any one area while length and the frequencies the enigma version was likely to be passed on were normally fairly accurately predictable.

The most famous of all these reencodements was Bereich 7 which broke Dolphin consistently from late 1942 to late 1943. This was a twice daily reencodement of weather from Trondjhem and it was normally possible to produce a right crib from it. The contents were rarely hatted and the only hazard was an addition at the end of the Dolphin message giving the information that a certain R.H.V. message need not be decoded as it had identical content. Another famous weather crib was Bereich 5 which broke most of the first 6 months of Plaice but which subsequently became security conscious and hatted the Werft version to such an extent that we could do nothing with it. By early 1945 it was so bad that we did not feel justified in asking that Werft should continue to be broken to assist us with Plaice. It was generally true of all reencodements that, if much hatting took place, we could make little use of them.

The other most prolific source of reencodements of this type was the mine laying, especially in the Baltic. Mine warnings and ‘all clears’ were sent out in Werft and then repeated for the Baltic U Boats. So good were these cribs that, if we were under pressure to obtain an early break, mines were laid deliberately with a view to producing cribs and most profitable results were obtained. We even put up suggestions as to the best places to lay mines: obviously Weg FUNF (or FUENF) ZIFFER (or ZIFFX or ZIFF) SIEBEN (or SIBEN) was a rotten place but


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