Beaufort Cipher
Use a repeating keyword with the reciprocal Beaufort rule C = K - P mod 26.
Input
Output
Using This Tool: Guide & Notes Show guide
The Beaufort cipher is a reciprocal keyword cipher. It uses the keyword letter minus the plaintext letter, modulo 26.
How to use it
- Enter a keyword, then paste the message into the input box.
- Use Encrypt or Decrypt for the task you are doing. Beaufort is reciprocal, so the core operation is the same in both directions.
- Check the output as you change the keyword or formatting settings.
- Use Load example to compare against a known Beaufort result.
Options and settings
- Keyword supplies the repeated key stream. A different keyword completely changes the output.
- Preserve case keeps the readable case style of the original message.
- Keep punctuation and numbers leaves unsupported characters in place.
- Group letters creates fixed-size blocks for classical ciphertext formatting.
Notes
- Beaufort is not the same formula as Vigenere, even though both use repeating keywords.
- Wrong keyword alignment usually makes the whole decrypted text unreadable.
Related Article
Beaufort Cipher guide coming soon
The matching article is not published yet. This tool is ready now, and the guide can be added through the shared article template when it is written.