Atbash Cipher Explained
The Atbash cipher swaps each letter with its mirror in the alphabet (A↔Z, B↔Y). It is a fixed monoalphabetic substitution—encrypt and decrypt with the same map. Practice related monoalphabetic skills on substitution mode or study substitution cipher theory.
What is the Atbash cipher?
Named after the first four mapped letters in Hebrew (aleph-taw-beth-shin), Atbash reverses the alphabet. In Latin letters: position i maps to 25−i. It appears in biblical scholarship and quick puzzle obfuscation.
Because the permutation is fixed, there is no secret key beyond “use Atbash.” Security is essentially nil for modern threats.
How Atbash encryption works
Encrypt HELLO → SVOOL (H↔S, E↔V, L↔O, O↔L). Apply the same map again to decrypt—Atbash is self-inverse. Implementation is a 26-letter substitution tableau.
Compare with Caesar shifts (rotation) and custom substitution decoders.
Why teach Atbash today?
It introduces involutions, complements Hebrew studies, and foreshadows general substitution tables before students tackle keyword-generated alphabets.
Use the Atbash decoder page for translator vocabulary and Atbash examples for classroom drills.
Frequently asked questions
What is an Atbash cipher?
A fixed cipher mapping each letter to its reverse in the alphabet (A↔Z).
Is Atbash the same as ROT13?
No—ROT13 shifts by 13; Atbash mirrors ends of the alphabet (A↔Z, B↔Y).
Does Atbash need a key?
The key is implicit—the reversal rule itself.
Can I run Atbash on Cipher Portal?
Use substitution mode with the Atbash tableau or decode manually; dedicated Atbash UI may ship later.
Practice monoalphabetic skills on Cipher Portal substitution and the Frequency Lab.