Beaufort Cipher
Enter an ASCII-letter key. Beaufort uses the same operation for encryption and decryption: key minus text, modulo 26.
A QUICK WALKTHROUGH
How to use this tool
- Enter text and a nonempty key made of ASCII letters A–Z.
- Choose Encrypt or Decrypt.
- Review and copy the result; processing happens locally in your browser.
Beaufort formula
Letters use A=0 through Z=25. Both encryption and decryption calculate (key − text) mod 26, so the same operation reverses itself. Case is preserved.
Text and key boundaries
The key must contain only ASCII letters A–Z or a–z. Only ASCII letters in the text consume key positions; spaces, punctuation, digits, accented letters, CJK text, and emoji remain unchanged.
A local learning tool
This is a classical cipher for learning and compatibility. It is not suitable for protecting passwords, secrets, or sensitive data. Text and keys stay in this browser.
GOOD TO KNOW
Common questions
Is Beaufort encryption the same as decryption?
Yes. Beaufort is reciprocal: key minus text is used in both directions.
Which characters change?
Only ASCII letters A–Z and a–z. Case is preserved and all other characters remain unchanged.
Can the key contain non-Latin letters?
No. The key must be nonempty and contain ASCII letters only; non-ASCII text remains unchanged.
Is Beaufort secure?
No. It is a classical cipher and should not protect secrets.