The History of Hut Eight

shown as ordered and was a very excellent crib.

To spot cribs of this type it was necessary to read through large quantities of traffic, covering perhaps a week or two, and to have a good short term memory which would react to seeing two similar messages. Work of this type was naturally more difficult and, as the years went by, the finding of possible cribs (as distinct from their exploitation) began to require more and more high grade labour. For a long time junior members of the Crib Room were relied upon for discovering new cribs by reading traffic in Naval Section but, as cribs became scarcer, it became obvious that this system was inadequate and we started having traffic redecoded on the carbon copies of messages so that they were available for scrutiny by senior cribsters. The desirability of this system was further stressed by the increasing numbers of reencodements which had to be recognized and preserved so that by 1945 nearly all the traffic was being decoded twice. In some respects this was an extravagant system as it required a large decoding staff but it meant that Naval Section received their decodes more quickly as all available typists set to work first of all on their copies and subsequently typed those for the Crib Room. The alternative scheme would have been to have an increased number of high grade cribsters so that someone was always available to examine decodes before they went to Naval Section.

The crib chosen as an example in the paragraph before last is interesting also for being a crib for a complete message. Cribs on the whole were only "beginners" but we had much success with very short messages for in these we got additional confirmation that our crib was right in that it finished up exactly in the last group of the message. An interesting example of this type was a little harbour report from the Mediterranean, it said:
HANSMAXVVVLECHXXAAAYYDDDFEHLANZEIGE. This was a 13 group message, if the message was 14 groups VVV had been changed to VONVON, one of the normal alternatives for which the cribster had to allow - others were FUNF or FUENF, SIBEN or SIEBEN, VIR or VIER, etc.. Most of these little messages that could be cribbed in toto were situation reports which said, in some form or other, "Nothing to report"; some of them were security conscious and filled up the message with dummy words which had the effect of degrading them to the level of a normal crib.

We shall meet one or two other rather curious straight cribs in the course of our historical survey, but one further crib must be mentioned here for fear it be forgotten altogether as, though often useful, it was never one of the cribs which formed our daily bread and butter. This was the POPTI crib, so christened by the decoders who were amused by the curious selection of letters it contained. We have seen that the German navy had


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