EncodeLab

Atbash Cipher

Encode and decode the reverse-alphabet Atbash cipher.

Atbash
UTF-8 Reverse alphabet

Ready

How the Atbash cipher works

Example The quick brown fox Gsv jfrxp yildm ulc
  1. Atbash replaces each letter with its alphabet opposite: A becomes Z, B becomes Y.
  2. The substitution reverses the alphabet, so the cipher is its own decoder.
  3. Numbers, punctuation, and spacing pass through unchanged.

Where Atbash comes from

Atbash appears in the Hebrew Bible, where it was used in the book of Jeremiah. The name itself describes the rule: the first letter of the Hebrew alphabet is swapped with the last, the second with the second-to-last, and so on.

Atbash is not secure

Like all substitution ciphers, Atbash preserves letter patterns and has no key at all. It is a historical curiosity and a teaching tool, never a real protection.

Related tools

Caesar Cipher Encode and decode Caesar-shifted text with an adjustable key. Caesar Cipher Decoder Decode Caesar-shifted text and compare all 25 possible keys. ROT13 Encode and decode ROT13 text in one step. Vigenère Cipher Encode and decode Vigenère text with a keyword. Morse Code Translator Translate text to Morse code and decode Morse back to text.

Frequently asked questions

How does Atbash work?

Each letter is replaced by its opposite in the alphabet: A becomes Z, B becomes Y, C becomes X, and so on through M ↔ N.

Is my input uploaded?

No. EncodeLab performs this conversion locally in your browser. Your input is not sent to an EncodeLab server or stored by us.

Is Atbash its own decoder?

Yes. Reversing the alphabet twice returns the original text, so encoding and decoding use the same operation.

Is Atbash secure?

No. It has no key, and its letter patterns can be broken with simple frequency analysis.