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Germany Hand Caesar Beaufort →
Polyalphabetic cipher disc
This cipher wheel was made by Linge in Pleidelsheim (Germany).
It is a variant of the well-known caesar cipher
of which the order of the alphabet on the inner disc is reversed.
This type of manual cipher system
is also known as the Reverse Caesar Cipher
and is a form of the Beaufort Cipher.
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The image on the right shows the cipher disc which is milled out of a solid
piece of brass. It consists of a fixed outer ring in which the 26 letters
of the Latin alphabet (A-Z) are impressed in clockwise order. The outer
ring has a milled-out area that holds the movable inner ring.
The inner ring is held in place by a bolt at the center and has the 26
letters of the Latin alphabet impressed in counter-clockwise order.
Also mounted to the bolt at the centre, is a
movable ruler that can be fixed
in any of 26 positions by means of a
knurled steel screw.
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The only indication that the cipher disc is manufactured in Germany,
is the name of the maker (Linge) and the city name (Pleidelsheim),
which are impressed at the bottom. The disc does not have a serial number.
A similar disc
[3] is shown on the German Wikipedia page about the Caesar Cipher
[1], but that one appears to be incomplete. It has an improvised bolt at
the centre and the ruler is missing. Furthermore is has a hole at the
top of the letter 'A' of the inner disc.
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A
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B
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C
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D
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E
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F
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G
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H
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I
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J
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K
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L
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M
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N
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O
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P
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Q
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R
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S
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T
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U
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V
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W
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X
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Y
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Z
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Z
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Y
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X
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W
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V
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U
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T
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S
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R
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Q
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P
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O
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N
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M
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L
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K
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J
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I
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H
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G
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F
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E
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D
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C
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B
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A
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The disc shown here is a variant of the Caesar Cipher,
of which one alphabet is in reverse order. When applied to the Hebrew
alphabet in a static manner, the reverse caesar cipher is known as Atbash [2].
In its basic form it is a simple substitution cipher (or: monoalphabetic
substitution), but as the inner disc is movable, it could be used as a polyalphabetic substitution as well.
If we align the letter 'P' of the inner disc with the 'A' of the outer disc,
the substitution is as follows:
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A
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B
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C
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D
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E
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F
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G
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H
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I
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J
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K
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L
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M
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N
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O
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P
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Q
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R
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S
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T
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U
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V
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W
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X
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Y
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Z
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P
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O
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N
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M
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L
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K
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J
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I
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H
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G
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F
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E
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D
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C
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B
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A
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Z
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Y
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X
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W
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V
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U
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T
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S
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R
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Q
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The advantage of the Reverse Caesar Cipher is that it is reciproke (reversible),
even when the inner alphabet is shifted. As a result, the same procedure can
be used for coding and decoding.
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At present we have no further information about this cipher disc, its
manufacturer or its age. If you have any additional information, please
contact us.
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Any links shown in red are currently unavailable.
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© Crypto Museum. Created: Thursday 11 September 2014. Last changed: Thursday, 18 February 2021 - 18:29 CET.
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