This document describes the Polybius square cipher which was a manual cipher system used to encrypt messages by substituting each letter with a number pair. The system works on a 5x5 square grid with letters assigned to the horizontal and vertical columns, allowing a two-digit code to represent each letter for encryption by mapping it to the number pair at the intersection.

1. O Código de polibio
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2. A
B
C
D
E
F
G
H
I
J
K/Q
L
M
N
O
P
R
S
T
U
V
W
X
Y
Z

3. 11
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4. 12
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5. 13
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6. 14
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7. 15
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8. 21
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9. 22
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10. 23
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11. 24
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12. 25
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13. 31
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14. 32
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15. 33
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16. 34
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17. 35
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18. 41
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19. 42
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20. 43
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21. 44
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22. 45
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23. 51
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24. 52
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25. 53
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26. 54
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27. 55
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