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Switzerland Hand
The device measures 208 × 30 × 5 mm and weights 92 grams. It consist of three
1 cm-wide metal rules, of which the outer two act as a frame in which the middle
one is movable.
The fixed (outer) rules hold the numbers 00-99, with the odd number on the
left and the even ones on the right. The movable centre piece, holds
the 26 letters of the Latin alphabet, the numbers 0-9 and some punctuation
characters. Also present on the slider are the most common bigrams for the
German language, such as 'de', 'ch' and 'st', plus a swap character;
50 in total.
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A second slider (identical to the one at the centre) is
stowed at the rear.
It should be chained to the existing slider, to allow wrapping of
the alphabet.
The device was in used until 1939, after which it was deemed insecure
by Dr. Hadwiger [2].
A simplified version of Réglette – for training purposes – was introduced
in 1949, under the name
Chiffrierschieber Cäsar (cipher slide Caesar).
To avoid confusion with other Caesar-based hand ciphers, we have named that one
Swiss Caesar.
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Réglette – sometimes written as Reglette – is the French word for
Ruler. In this context it means Slide Rule.
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For encryption of messages, a cryptographic KEY is needed – consisting
of a Keyword and a two-digit Key Number – that has to be known by the
recipient. In case of (war) mobilisation, suitable KEYs would be
issued by the General Staff Department of the Army [2].
An example of a KEY is:
DREHZAHL 37
Shift the slider, so that the first letter of the Keyword (D) lines up with the
Key Number (37). Now find the first character of the plain text on the slider,
and write down the number next to it. Now move the slider so the the second
letter of the Keyword lines up with the Key Number. Find the second letter of
the plain text and write down the number next to it. As soon as all letters of
the Keyword are used, continue with the first letter of the Keyword,
until the message is complete.
For long messages – consisting of more than 15 to 20 words – it is
recommended to split it into several parts, using the swap character
( i.e. the hatched field) to indicate the start of the next part. For each part,
a new Key Number should be used (subject to the issued KEY instructions).
DREHZAHL 37 51 00 92 78
Once the message is complete, the cipher text – consisting of 2-digit
numbers – must be written out in groups of 5 digits each. If the last group
is partly unused, it should be padded with random digits. The message
is now ready for transmission via radio
(morse-code), letter or telegram.
At the receiving end, the message can be decrypted by using the above
procedure in reverse order.
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© Crypto Museum. Created: Sunday 03 September 2017. Last changed: Monday, 09 August 2021 - 06:46 CET.
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