All tools › Shifting the alphabet
Vigenère cipher
Encipher with a keyword, or hand it a ciphertext and let it work out the key length and the key.
It runs entirely in this browser tab: the text you paste is never uploaded, and the tool makes no network request while it works. Open your browser's network panel and try it — nothing leaves the page. There is no sign-up and no limit beyond what your own browser can hold.
Settings
- What to do
- Choices: Encipher, Decipher, Break it.
- Variant
- Choices: Vigenère, Beaufort, Autokey.
- Key
- Text you supply.
- Alphabet
- Choices: Latin A–Z, Slovak, with accents, Greek α–ω, Own.
- Your own alphabet
- The letters in order, each one once
- Keep spaces and punctuation
- Off, the result is letters only — which is how a cipher was actually sent.
- Key length
- Zero lets the tool find it from the index of coincidence. A number from 0 to 20.
- Compare with
- The published letter frequencies of ordinary prose in that language. Choices: English, Deutsch, Español, Français, Italiano.
- Show the working
- Replaces the result with the cipher's own workings: the grid or key it is using, or what it did to each letter.
How to use it
- Paste your text into the box above, or open a file.
- Adjust the settings beside it until the result is what you wanted.
- Copy the result, or save it as a file. The result updates as you type.
Questions
- Is my text uploaded anywhere?
- No. This page carries the whole tool as WebAssembly and runs it on your own device. Nothing you paste is sent anywhere.
- Is this secure?
- No. Every cipher on this site is a puzzle cipher, and the tool says so on each result. They are for escape rooms, cryptograms, coursework and historical curiosity.
- Can I get this result again later?
- The settings travel in the page's address, after the #, so a link reproduces them exactly — key included — and the fragment of an address is never sent to a server. Your last settings are also remembered on this device, which is worth knowing before you type a key you care about.
- Is there a version that is not a web page?
- Yes. The same ciphers are built as a desktop application from the same code, with a save dialog instead of a download and no network code at all.
Other tools for shifting the alphabet
ROT13
Move every letter thirteen places, which both hides and reveals. ROT5 and ROT47 too.
Caesar cipher
Shift the alphabet by any amount, or see all twenty-six shifts at once and pick the readable one.
Affine cipher
Multiply and then add, with the tool checking that the key can be undone and saying why when it cannot.
All twenty ciphers