Nihilist Cipher Encoder

How to Use the Nihilist Cipher Encoder

1. Enter your plaintext message in the "Message" field (letters A-Z only)
2. Enter a keyword for the Polybius square (optional, default is standard alphabet)
3. Enter a second keyword for the encryption key
4. Click "Encrypt" to encode your message
5. View the encrypted result as numbers in the output section

About the Nihilist Cipher

The Nihilist cipher is a symmetric encryption cipher that uses a Polybius square and a keyword. It was used by Russian Nihilists in the 19th century. The encryption process involves:

1. Creating a 5x5 Polybius square (I and J share a cell) using a keyword or standard alphabet
2. Converting each letter of the plaintext to its row/column numbers in the square
3. Converting the encryption keyword to numbers using the same square
4. Adding the plaintext numbers to the keyword numbers to produce the ciphertext

For decryption, the recipient needs both keywords to reverse the process.