One of the oldest known substitution ciphers: it reverses the alphabet, so A becomes Z, B becomes Y, and so on. It's self-inverse — apply it twice and you get your original text back.
⚠️ Educational/puzzle tool only — do not use this for real security purposes.
Atbash originated as a substitution cipher for the Hebrew alphabet. The name itself comes from combining Aleph and Taw (the first and last Hebrew letters) with Bet and Shin (the second and second-to-last letters) — Atbash is among the oldest known ciphers on record. The same reversal technique was later applied to the Latin alphabet.
Atbash works through a fixed correspondence that mirrors the alphabet front-to-back: A↔Z, B↔Y, and so on. There's no shift amount or keyword involved at all. That means applying the operation twice returns the original text — it's self-inverse — which sets it apart from ciphers like Caesar or Vigenère that need a shift or keyword to decrypt.
Because there's no key whatsoever, Atbash isn't really "encryption" so much as a fixed obfuscation or puzzle transform. Anyone who knows the rule can recognize and reverse it instantly, which makes it entirely unsuitable for protecting anything real. Use this tool strictly for education and puzzles.