Polybius

The Polybius Square cipher is a substitution cipher that uses a 5x5 grid to encode letters from the plaintext into 2 digits, represented by row and column numbers.

Preserve Symbols

Preserve Whitespace

Encode

Keyword

Input Message

Output Message

Explanation

The Polybius Square cipher, also known as the Polybius checkerboard, is a method of encryption that replaces pairs of letters with coordinates from a grid.

The cipher typically uses a 5x5 grid, with the letters of the alphabet (usually excluding 'J') arranged within it. Each letter is represented by its row and column coordinates in the grid. For example, if 'A' is in the first row and first column, it could be represented as '11', and if 'B' is in the first row and second column, it could be represented as '12'.

In this grid, each letter is represented by its row and column coordinates. For instance, 'A' is at coordinates (1,1), so it's encoded as '11', 'B' is at (1,2), so it's encoded as '12', and so on.

To encrypt a message using the Polybius Square cipher, each letter is first located in the grid, and then its coordinates are noted down. These coordinates form the encrypted message. To decrypt the message, the process is reversed: each pair of coordinates is converted back into the corresponding letter from the grid.

It's a relatively simple cipher, but it provides a method of encryption that can be implemented by hand without requiring complex mathematical operations. However, it's also relatively easy to break using frequency analysis or other cryptographic techniques.

Facts

It was named after the ancient Greek historian Polybius who first described it in the 2nd century B.C.