Atbash cipher
The Atbash cipher replaces each letter with its mirror image in the alphabet, so the first letter becomes the last. Type or paste text and the result appears at once. The same step encodes and decodes.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Type or paste your text into the first box.
- Read the result below it and press Copy to take it.
- To decode, paste the coded text in the same box. It is the same operation.
How it works
Number the letters 0 to 25. A letter at position p is replaced by the letter at position 25 − p. So A (0) becomes Z (25), and M (12) becomes N (13). Because the pairs are symmetric, applying the cipher a second time restores the text.
Worked example
“Hello” becomes “Svool”: H pairs with S, e with v, l with o, and o with l. The text “wizard” becomes “draziw”.
Tips
Atbash is a good first cipher for a puzzle hunt because it needs no key. If you want something with a setting, try the Caesar cipher, where you choose the shift, or the Vigenère cipher, which uses a keyword.
Frequently asked questions
What is the Atbash cipher?
It is a simple substitution cipher in which the alphabet is reversed. A becomes Z, B becomes Y, C becomes X, and so on. It was first used with the Hebrew alphabet; this tool applies the same idea to the 26 Latin letters.
How do I decode an Atbash message?
Paste it in the same box. Mirroring the alphabet twice gives back the original, so encoding and decoding are the same operation and there is no mode or key to choose.
Which characters are changed?
Only the Latin letters A to Z and a to z, and their case is kept. Digits, spaces, punctuation, accented letters and other alphabets pass through unchanged.
Is Atbash secure?
No. There is no key, so anyone who knows the method can read the message. Use it for puzzles, games and learning about ciphers, never to protect anything private.