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Hand
Caesar cipher
Vigenère cipher
  
k.u.k. Chiffrierscheibe
Austrian variant of the Vigenère cipher - under construction

The k.u.k. Chiffrierscheibe 1 was a simple alphabet substitution and transposition cipher, used by the Austrian k.u.k. Army 2 prior to or during World War I (WWI). The system is basically a variant of the well-known Vigenère Cipher — using a transposed extended alphabet — which in turn is based on the disc variant of the Caesar transposition cipher. The system offers limited security.

The image on the right shows one of the few surviving 3 original k.u.k. cipher discs [1]. The device consists of two concentric carton discs that can rotate around a metal clip at the centre.

The inner disc has a diameter of 103 mm and is marked SCHEIBE I (disc 1). It has the full German alphabet plus the numbers 0-9 printed in blue around its outer rim (40 characters in total). This disc is used for the plaintext. The outer disc has a diameter of 163 mm and is marked SCHEIBE II (disc 2). The outer rim is printed in green with the same alphabet in random (scrambled) order.
  
KuK variant of the Caesar Disc

The outer disc also holds a ring with the numbers 1-40 printed in red in ascending (clockwise) order. The number is probably used to set the KEY (i.e. the transposition or shift of the alphabet). Depending on the operational procedure, the k.u.k. Chiffrierscheibe can be described as a mono-alphabetic substitution cipher, or a poly-alphabetic substitution cipher. In operation, it is similar to the Dutch Army's Caesar Wheel, that was used during the Cold War for training purposes.

  1. Chiffrierscheibe = Cipher Disc (German).
  2. k.u.k. = Kaiserlich und Köninglich (Imperial and Royal). Refers to the Dual Monarchy of Austria-Hungary from 1967 to 1918. Also written as k. und k. and as k. & k..  Wikipedia
  3. At present, the disc shown here is the only one known to have surviced [1].

KuK variant of the Caesar Disc Front side Rear side Detail Detail Scheibe II (disc 2) Text written at the rear side Pivoting point seen from the rear of the disc
A
×
A
1 / 8
KuK variant of the Caesar Disc
A
2 / 8
Front side
A
3 / 8
Rear side
A
4 / 8
Detail
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5 / 8
Detail
A
6 / 8
Scheibe II (disc 2)
A
7 / 8
Text written at the rear side
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8 / 8
Pivoting point seen from the rear of the disc

Plain   Code Cipher
a   1 a
b   2 h
c   3 p
d   4 w
e   5 ch
f   6 6
g   7 1
h   8 e
i   9 v
j   10 q
k   11 l
l   12 f
m   13 8
n   14 ö
o   15 r
p   16 2
q   17 z
r   18 u
s   19 k
t   20 9
u   21 m
v   22 0
w   23 n
x   24 j
y   25 y
z   26 s
ä   27 3
ö   28 ü
ü   29 x
ch   30 d
1   31 4
2   32 i
3   33 o
4   34 5
5   35 t
6   36 c
7   37 g
8   38 b
9   39 ä
0   40 7
Help wanted
The exact purpose and era of the k.u.k. cipher disc is still unknown. Although it is likely that the cipher was used for tactical (low-grade) traffic, it is unknown which regiment or battalion used it. If you have any additional information please contact us.


References
  1. Günter Hütter, K.u.K Chiffrierscheibe
    Retrieved October 2017.
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© Crypto Museum. Created: Sunday 12 November 2017. Last changed: Saturday, 24 February 2018 - 10:55 CET.
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