Polybius Square Cipher

Use Polybius Square Cipher for its specific task

The focused purpose of Polybius Square Cipher is learning a classical fractionation cipher or preparing a pencil-and-paper puzzle. A five-by-five alphabet grid merges I and J, then represents each letter by its one-based row and column. Spaces separate encoded pairs; decoding maps each valid pair back to its grid letter. By pairing this method with a visible result, Polybius Square Cipher exposes how it encodes letters as row-column digit pairs and decodes them instead of hiding the task behind a generic shell.

HELLO encodes as 23 15 31 31 34 with the standard alphabet arrangement. Because I and J share one cell, decoded text cannot recover which of those two letters was originally used. The visible default provides a reproducible verification case for Polybius Square Cipher, while its labeled controls let another value be checked without changing the underlying method.

Method limits and local processing

The fixed square is a historical teaching cipher and offers no modern confidentiality. Polybius Square Cipher performs its work locally in your browser and does not send the entered text, values, credentials, or selected file to a server. Keep that stated boundary with the result because this page intentionally handles only encodes letters as row-column digit pairs and decodes them.