selected from a set of 244 trigrams.
The E’ indicating system was also used for a method of "cyphered conversation" which was developed -- but not extensively -- after 1943. The cyphered text was sent over the air letter by letter so that the receiver could decode each letter on his enigma machine as he picked it up and record only the clear text. This was normally in conversational German and of no cryptographic value.
iii. B-Bars, etc. (kurzsignale)
B-Bars, Rossaries, and Short E's were designed to enable U-Boats and surface craft to send a limited number of standard messages without having to risk being D/Fed through surfacing or transmitting for more than a few seconds.
In 1940-1 different code books and indicator tables were used by surface craft and U-Boats, but in January 1942 an all embracing system was introduced. The various systems are described below.
a) Rossaries (Flottenkurzsignale) up to January 1942.
The Flottenkurzsignalheft (C, I) was used by Fleet units down to destroyers, raiders, and associated auxiliaries, and later by U-boats (though the book was not designed for them).
Nothing is known of the first edition but the second edition (German name Feodor) was introduced on December 12th 1940. It was a systematically arranged phrase book with equivalent 4-letter groups with each group (say abcd) obeying the rule a+d=b=c mod 26. Groups were arranged alphabetically (with omissions) e.g.
KCKC My position is Grid square BE51.
KCME ----------------------------------- BE52.
or DHAE am starting return passage on.........
The indicator tables issued with the book consisted of 2 tables of 26 message settings, each corresponding to a letter of the alphabet. The tables were to be used in odd and even months respectively.
A cyphered signal consisted of:
Indicator letter repeated twice.
Time of Origin.
1 - 6 cyphered 4 letter groups.
Cyphered 2 letter signature.