Cipher 101 Tutorials
Polybius Square Cipher Tutorial
What is a Polybius Square?
The Polybius Square is a table that allows one to translate letters into numbers. It was originally invented by the ancient Greek historian Polybius. The most common form is a 5x5 grid, where each letter of the alphabet is placed (I and J are usually combined to fit the 25 squares).
How it Works
Each letter is represented by its coordinates in the grid. For example, in the standard 5x5 grid, 'A' would be '11', 'B' would be '12', and so on.
Standard 5x5 Polybius Square:
| 1 | 2 | 3 | 4 | 5 | |
|---|---|---|---|---|---|
| 1 | A | B | C | D | E |
| 2 | F | G | H | I/J | K |
| 3 | L | M | N | O | P |
| 4 | Q | R | S | T | U |
| 5 | V | W | X | Y | Z |
To encrypt "HELLO", you would find the coordinates for each letter: H=23, E=15, L=31, L=31, O=34. So "HELLO" becomes "2315313134".