The History of Hut Eight

the remaining unused numbers in a stated order; the final settings are obtained from these numbers taken out vertically.

"The effect of this procedure is that for the duration of an inner setting the same new wheel order is obtained, but the daily change in the printed 'Stecker' brings with it the daily change in the 'Ringstellungen' which was first observed on 3/4/45."

The other forms of emergency procedure were those which came into force when there was a danger of a station falling into enemy hands and when it had proved impossible to distribute the new month's keys. In the case of imminent danger K book, bigram tables, and keys were destroyed but a key was to be made up from the inner settings of one day and the outers of another and these settings were to remain in force until the station was captured. We had a number of keys of this type at odd times, traffic usually being distinguished by having the first 2 letters of the place name in the preamble. In the other case where keys had not been distributed it was usual to reuse old keys in some sort of hatted order: a lot of this type of thing went on in late 1944.

One other event of importance occurred during 1941 - the breaking of Offizier in late October.


1. Offizier

The idea of Offizier keys was that there should be some method of communicating highly confidential or operational information to captains of ships or senior shore authorities without the W/T ratings' knowledge. The system was that the officer encyphered his message on a private key and then handed it to the cypher operator who recyphered it with a preamble to the effect that it was an Offizier message the end of which would be decoded on Offizier keys. The recipient discovered this after decoding the first time and handed the machine over to an officer for final decoding.

The Offizier keys varied somewhat in form but they have in common that the wheel order remains the same as that of the ordinary key and that lists of 26 settings are used. The officer did not use any Grundstellung procedure but chose his letter and encyphered his message at the set up equivalent to it. Thus an Offizier message will always state that it is an Offizier Bruno or Paula or such like. These 26 settings remained valid for a whole month. Some keys - Barnacle, Conch, Cowrie - were content to keep simply this private list of settings for officers and to recypher the messages on the ordinary Stecker but the normal procedure was to have a private Stecker as well; this usually changed every two days, but in the case of U Boats after August 1943 it only changed once every 10 days.


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