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Substitution cipher

Every letter swaps for another, all twenty-six scrambled. Shuffle an alphabet, or type your own.

The letters A to Z become, in order. All 26, once each.

Result

The link opens a page that reads it. Without the key, your friend has to crack it. The message travels after the # in the link, which a browser never sends to our server.

Substitution chart

Every letter, A to Z with the alphabet QWERTYUIOPASDFGHJKLZXCVBNM.

Where it comes from

Every letter swaps for another, all twenty-six scrambled. There are more possible keys than grains of sand on Earth, but letter frequencies give it away: E is still the commonest letter, whatever it is dressed as.

A message worth knowing: A good glass in the bishop's hostel. The opening of the hidden message in Edgar Allan Poe's story The Gold-Bug (1843). A scrap of parchment carries a substitution cipher, and Legrand breaks it by counting which symbol turns up most.

Learn it by heart

This is the cipher desk from Covert Mail, our free app for learning codes. The app teaches Substitution a few characters at a time, plans practice around the ones you miss, and keeps an archive of famous real messages to unlock. It is coming soon to the App Store and Google Play.

Coming soon to the App Store and Google Play

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