Cabinet Noir
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Polybius coordinates plus a repeating numeric key, added digit by digit without carry — Vigenère on numbers.
Type
polyalphabetic substitution cipher
Breaking it
medium to break by hand
Era
Russia, 1880s
Name
Russian Nihilist prisoners smuggling numbers past the censors; a forerunner of the VIC cipher
Modes
encrypt · decrypt · cryptoanalysis
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Tool
Cryptoanalysis
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Practice
Practice
Nihilist cipher
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Seven letters from Siberia
Easy
67 68 64 26 85 68 34 58 36 27 58 86 58 32 87 48 44 30 85 48 55 95 35 55 59 65 39 63 77 66 55 59 76 45 55 67 56 27 58 66 68 63 54 67 56 38 57 35 33 58 58 33 67 66 67 25 77 56 36 59 94 35 54 87 47 27 26 64 39 45 64 45 46 49 73 48 54 66 57 27 58 85 48 55 95 35 55 59 65 39 54 58 35 55 49 75 58 32 74 48 34 38 86
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Revolutionary post
Medium
66 59 75 77 42 89 86 69 78 56 87 48 75 85 46 87 87 35 65 64 96 26 64 59 64 79 96 55 49 47 64 30 65 78 54 56 88 35 77 57 75 37 82 49 63 56 77 48 67 68 76 58 94 49 74 88 68 58 67 67 63 26 73 68 65 59 65 58 76 77 87 48 66 66 76 88 88 36 49 57 75 67 62 67 75 79 65 35 86 57 63 30
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The keyed square
Hard
66 45 83 77 48 47 25 89 65 54 73 56 48 57 65 69 82 87 56 54 79 46 34 76 53 45 83 77 60 54 58 77 65 77 45 55 79 45 64 76 73 78 57 45 79 78 45 57 82 78 64 66 48 47 25 86 86 66 73 57 76 78 34 86 65 48 73 54 80 66 25 86 55 45 73 47 59 66 65 69 64 66 73 68 68 55 37 89 86 87 53 74 58 56 37 68 74 47 53 78 59 56 58 57 86 65 56 75 79 45 55 57 54 66 77 66 47 74 58 77 62 78 53 68 70 44 37 86 62 77 56 47 79 57 34 90 65 56 56 76 86 54 48
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Created by Denys Grybov in 2021
v.0.4.0 // released on 25.10.2026