The Vigenère cipher already gets its own tool on this site, but there’s a lesser-known sibling worth exploring: the Beaufort cipher, named for Sir Francis Beaufort of wind-scale fame. It swaps the order of subtraction in the Vigenère formula — a tiny change that makes the whole cipher reciprocal.
What Is the Beaufort Cipher Tool?
Enter text and a repeating key, and the tool computes C = (K − P) mod 26 for every letter. Because this formula is its own mathematical inverse, there’s no separate decrypt mode — running the exact same operation on the ciphertext with the same key recovers the original plaintext.
How to Use It
- Open the tool at /tools/beaufort-cipher.
- Type your text.
- Type a key (letters only — it repeats cyclically to match your text’s length).
- Click “Encrypt / Decrypt” — the same button does both, since the operation is reciprocal.
Key Features
- One reciprocal operation for both encryption and decryption — verified to recover the exact original text when run twice with the same key.
- Repeating-key support, just like Vigenère.
- Non-letter characters pass through unchanged, preserving spacing and punctuation.
When to Use This Tool
- Learning the difference between Vigenère and its reciprocal Beaufort variant.
- Understanding what makes a cipher “self-inverse.”
- Solving or building cryptography puzzles that use the Beaufort cipher specifically.
Try It Now
Open Beaufort Cipher directly, or press ⌘K and type the tool name from anywhere on the site.
Part of the Security & Crypto collection on WebdevToolbox — free, browser-based developer tools with no login required.