All tools › Keys from outside the message
One-time pad
The one cipher that cannot be broken — as long as the key is random, as long as the message, and never used twice.
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, Make a new pad.
- The pad
- As many random letters as the message has, used once and then destroyed.
- Alphabet
- Choices: Latin A–Z, Slovak, with accents, Greek α–ω, Own.
- Your own alphabet
- The letters in order, each one once
- Write in groups of
- Five is the convention: it makes a message countable by hand and hides the word lengths. Zero writes it in one run. A number from 0 to 10.
- Seed
- Zero gives a different result every time; any other number repeats this one exactly. A number from 0 to 1000000.
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 keys from outside the message
XOR cipher
Exclusive-or bytes against a repeating key, in hex or Base64 — and try all two hundred and fifty-six single-byte keys.
Book cipher
Write a message as numbers pointing into a text both sides already have, and read it back.
Enigma machine
Rotors, ring settings, reflector and plugboard, wired as they were — double step and all.
All twenty ciphers