Cabinet Noir
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Every letter of the message becomes the row and column numbers of its cell in a 5×5 grid.
Type
substitution cipher
Breaking it
trivial to break
Era
Classical Greece, 2nd century BC
Name
Polybius' torch-signalling scheme, later the basis of tap code and fractionation
Modes
encrypt · decrypt
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Polybius square cipher
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Numbers in the night
Easy
43 34 43 52 15 23 11 51 15 43 44 42 45 13 25 11 33 24 13 15 12 15 42 22
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A truth, in coordinates
Medium
24 44 24 43 11 44 42 45 44 23 45 33 24 51 15 42 43 11 31 31 54 11 13 25 33 34 52 31 15 14 22 15 14 44 23 11 44 11 43 24 33 22 31 15 32 11 33 24 33 35 34 43 43 15 43 43 24 34 33 34 21 11 22 34 34 14 21 34 42 44 45 33 15 32 45 43 44 12 15 24 33 52 11 33 44 34 21 11 52 24 21 15
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The Spartan square
Hard
31 43 45 14 11 23 43 14 25 13 21 24 11 25 51 25 21 54 25 13 14 11 13 32 43 43 45 14 31 13 15 33 25 14 11 22 14 43 45 32 33 15 31 43 14 15 33 43 21 15 33 34 11 23 43 21 15 34 21 25 21 15 13 21 25 52 21 13 15 34 43 21 23 43 21 23 25 34 51 25 24 34 21 41 34 22 25 14 15 54 13 21 24 24 25 24 34 23 13 15 25 24 15 43 15 33 25 12 14 43 12 43 11 34 15 34 43 21 15 33 13 15 13 41 41 42 25 21 13 14 25 23 14 25 13 15 25 24 25 44 45 13 41
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Created by Denys Grybov in 2021
v.0.4.0 // released on 25.10.2026