Bifid Cipher
Encrypt and decrypt with the Bifid cipheral, a complex substitution cipher that combines a Polybius square with fractionation. Instead of replacing one letter with another, it converts letters into coordinates, stacks them, and then reads them as a new sequence of coordinates to find the resulting letters. This process breaks the relationship between the plaintext and ciphertext, making it significantly harder to crack than simple substitution. Everything runs locally in your browser.
Encrypt (plaintext → cipher)
Decrypt (cipher → plaintext)
The math. The Bifid cipher uses a 5×5 Polybius square (merging I/J). Each letter is converted to a coordinate pair (row, col). For a message of length $L$, we write the row coordinates of all $L$ letters, followed by the column coordinates of all $L$ letters. This sequence of $2L$ numbers is then split into pairs, and each pair is converted back into a letter using the same square. Decryption reverses this by splitting the ciphertext into rows and columns based on the message length. Pairs with the Polybius Square and Vigenère cipher tools. Everything runs locally — nothing leaves your browser.