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Atbash Cipher

Tool to decrypt/encrypt with Atbash (Mirror code), a substitution cipher replacing the first letter of the alphabet with the last, the second with the penultimate etc.


Atbash Cipher -

Tag(s) : Substitution Cipher

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Atbash Cipher

Atbash Decoder


Atbash Encoder


Answers to Questions (FAQ)

What is Atbash cipher? (Definition)

Atbash cipher (also called mirror cipher or backwards alphabet or reverse alphabet) is the name given to a monoalphabetical substitution cipher which owes its name and origins to the Hebrew alphabet.

Atbash replaces each letter with its symmetrical one in the alphabet, that is, A becomes Z, B becomes Y, and so on.

How to encrypt using Atbash cipher?

Atbash encryption uses a substitution alphabet and its reciprocal, a combination of the normal alphabet and its reverse alphabet (mirrored).

Example: The latin alphabet ABCDEFGHIJKLMNOPQRSTUVWXYZ and its reverse: ZYXWVUTSRQPONMLKJIHGFEDCBA are combine in the substitution table:


Encryption consists in replacing letters from the first with letters from the other one, with is equivalent to replace the first letter of the alphabet A with the last one Z, the second one B with the penultimate Y etc.

Example: MIRROR becomes NRIILI

How to decrypt Atbash cipher?

Decryption is identical to encryption because of the reversible alphabet (due to the symmetry of the backwards alphabet)

Example: ZGYZHS is decrypted ATBASH

dCode offers an encoder and a decoder, but they are actually one and the same Atbash converter.

How to recognize an Atbash ciphertext?

An Atbash ciphertext has a coincidence index similar to an unencrypted text.

If the encryption used the classical latin alphabet, letters V,G,R,L,M appear the most frequently.

Otherwise the presence of Hebrew characters or a reference to the Dead Sea can be a clue.

The notions of mirror, reflection, opposite, axis, direction, word written in reverse (hsabta) are also clues.

Why is this cipher called 'Atbash'?

In the Hebraic alphabet, aleph (first letter) was replaced by tav (last letter) and beth (second letter) with shin (second last), etc. Initials make A,T,B,SH.

How is the Atbash number used in the Hebrew Bible?

The number Atbash is mentioned in the Hebrew Bible, notably in the book of Jeremiah (chapter 25, verse 26 and chapter 51, verse 41). It is used to replace the name of certain kings and countries with their coded equivalents.

What dictionary words still exist when encrypted?

There are a small number of words that have an existing Atbash equivalent in the English dictionary.


In Hebrew, this situation is more common (notably because the alphabet has no vowels).

What are Atbash variants?

Atbash is adaptable to any alphabet, so using the Hebrew alphabet is possible.

The atbash cipher is equivalent to an affine cipher with $ a = -1 $ and $ b = -1 $

The atbash cipher is equivalent to a monoalphabetic substitution with the alphabet ZYXWVUTSRQPONMLKJIHGFEDCBA

When was Atbash invented?

The exact origin of the Atbash cipher is uncertain, but it is known to have been used in ancient Israel around the 6th or 5th century BC.

Source code

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