The History of Hut Eight

There were no other differences between B's and Short E's, and B's also were used for obtaining Augsburg settings.

d) B-Bars (Kurzsignale) January 1942 onwards.

On 1.1.42 the Flottenkurzsignalheft and U Bootskurzsignalheft were withdrawn and replaced by Kurzsignalheft 1941 (C) which was issued to U-Boats and Fleet units alike. This code book was an enlargement of Feodor with new 4 letter groups to cover (a) the complete Naval Grid and (b) all special U-Boat requirements. No other Short Signal book was necessary. In practice the book was used almost exclusively by U-Boats, the most frequently used parts of the 120 page book being:

Part 3 Enemy Reports Groups beginning with C.
9 Rendezvous      "              "           " F.
14 Grid Squares      "              "           " J, K, P.
16 Numbers      "              "           " M, N.
18 Dates      "              "           " P.
19 Time of day      "              "           " P.
20 Course Indication      "              "           " Q.
21 Speed Indications      "              "           " Q.
24 Homing Reports, Beacons      "              "           " U.
27 Groups for Dummy Signals      "              "           " W.

In spite of the length of the book, the alphabetical arrangement of groups and the orderly arrangement of phrases made an inverse book unnecessary.

With Kurzsignalheft 1941 was issued Kenngruppenheft Nr. 1 zum Kurzsignalheft 1941 (I) -- an indicator book containing 310 numbered indicator trigrams with the equivalent message settings e.g.

161 EWB gives setting DOV
162 RAS     "        "       ZBS

The numbers acted as discriminants, different blocks of numbers being allotted to particular keys (according to the day of the month). All indicator trigrams in Kenngruppenheft Nr. 1 obeyed the rule a+b = c (mod 25). The letter I never occurred and was left out of the alphabet.

Kenngruppenhefts 1, 2, 5 and 6 were brought into force successively, number 6 having 400 instead of 310 indicators.

The following example shows a typical B' of the period.



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