Atbash Cipher — Reverse Alphabet Decoder & Encoder

The Atbash cipher is one of the oldest known ciphers — a reverse alphabet substitution that maps A↔Z, B↔Y, C↔X, and so on. Originally used in ancient Hebrew texts including the Bible, this monoalphabetic mirror cipher is self-inverse: the same operation encrypts and decrypts your text. Use this free Atbash cipher decoder and translator to convert any message instantly.

"HELLO"→"SVOOL"(Mirror)
Bidirectional- Same process for encrypt & decrypt
Result
0 characters
Character Sets:
LettersNumbersSpecial

Character Mapping

Letter Mapping (A ↔ Z)

A
↓
Z
B
↓
Y
C
↓
X
D
↓
W
E
↓
V
F
↓
U
G
↓
T
H
↓
S
I
↓
R
J
↓
Q
K
↓
P
L
↓
O
M
↓
N
N
↓
M
O
↓
L
P
↓
K
Q
↓
J
R
↓
I
S
↓
H
T
↓
G
U
↓
F
V
↓
E
W
↓
D
X
↓
C
Y
↓
B
Z
↓
A

Advanced Atbash Cipher Tools

Advanced Decoder

Break Atbash encryption with confidence scoring and step-by-step analysis

  • • Automatic Atbash detection
  • • Confidence level analysis
  • • Batch processing support

Examples & Code

Interactive examples with Python and JavaScript implementations

  • • Hebrew examples analysis
  • • Code implementation guides
  • • Interactive practice exercises

Hebrew Atbash

Original Hebrew alphabet cipher with historical context and analysis

  • • Hebrew alphabet support
  • • Biblical references (Jeremiah)
  • • Historical cryptography

Frequently Asked Questions About Atbash Cipher

What is the atbash formula?

The Atbash formula reverses the alphabet: position = alphabet_length - 1 - original_position. For English, A (position 0) becomes Z (position 25), B becomes Y, etc.

What is atbash used for?

Originally used in Hebrew texts and biblical manuscripts, Atbash is now used for educational purposes, puzzles, and understanding classical cryptography principles.

How to use atbash code?

Simply replace each letter with its mirror position in the alphabet. A↔Z, B↔Y, C↔X, etc. Our online tool automates this process with real-time conversion.

What is the Atbash cipher technique?

Atbash is a monoalphabetic substitution cipher that maps each letter to its mirror position. It's self-inverse, meaning applying it twice returns the original text.

Where is Atbash found in the Bible?

Atbash appears in Jeremiah 25:26 where "Sheshach" (ששך) encodes "Babel" (בבל), and in Jeremiah 51:1 where "Leb Kamai" encodes "Kasdim" (Chaldeans).

Is Atbash secure for modern use?

No, Atbash offers no security against modern cryptanalysis. It has no key and can be easily broken through pattern recognition. It's valuable only for educational and historical purposes.

What is the Atbash cipher?

The Atbash cipher is a monoalphabetic substitution cipher that reverses the alphabet — A becomes Z, B becomes Y, C becomes X, and so on. It originated in ancient Hebrew cryptography and appears in the Bible (Book of Jeremiah). The name 'Atbash' comes from the Hebrew letters Aleph-Tav-Beth-Shin, representing the first-last-second-penultimate letter pairs. It requires no key and is self-inverse, meaning applying it twice returns the original text.

How do you decode an Atbash cipher?

To decode Atbash, replace each letter with its reverse-alphabet counterpart: A↔Z, B↔Y, C↔X, D↔W, and so on. Since Atbash is self-inverse, the decoding process is identical to encoding — just run the same substitution. For example, 'SVOOL' decodes to 'HELLO' because S→H, V→E, O→L, O→L, L→O. Our free online Atbash decoder does this conversion instantly for any length of text.

What is a reverse alphabet cipher?

A reverse alphabet cipher — also known as Atbash or mirror cipher — is an encryption method that maps each letter to its opposite position in the alphabet. The first letter (A) swaps with the last (Z), the second (B) with the second-to-last (Y), and so on through the entire alphabet. It is one of the simplest classical ciphers and serves as a foundation for understanding more complex substitution ciphers.

How is Atbash cipher different from Caesar cipher?

Atbash and Caesar are both monoalphabetic substitution ciphers, but they work differently. Atbash reverses the entire alphabet (A↔Z, B↔Y) and requires no key — there is only one possible Atbash alphabet. The Caesar cipher shifts each letter by a fixed number (e.g., shift 3: A→D, B→E), offering 25 possible keys. Caesar cipher is slightly more flexible due to the variable shift, while Atbash is always the same fixed substitution.

Cipher Identifier →Caesar Cipher →Keyword Cipher →Vigenère Cipher →Affine Cipher →Compare Ciphers →

Related Ciphers

Caesar Cipher

Shifts each letter by a fixed number of positions in the alphabet

Affine Cipher

Mathematical cipher using linear function E(x) = (ax + b) mod 26

Keyword Cipher

Rearranges the cipher alphabet using a secret keyword

Pigpen Cipher

Masonic cipher that replaces letters with geometric symbols from a grid pattern

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Atbash Cipher: Ancient Hebrew Mirror Encryption - Free Online Tool

The Atbash cipher (Hebrew: אתבש) is one of the oldest known encryption methods in human history, dating back to at least 500-600 BCE. This ancient Hebrew cipher was originally used by Hebrew scribes to encode sensitive information in biblical texts and other important documents, making it a cornerstone of classical cryptography and ancient encryption techniques.

This reverse alphabet cipher is also known as the mirror cipher because it works by substituting each letter with its mirror position in the alphabet. As a monoalphabetic substitution cipher, Atbash represents humanity's earliest attempts at secure communication and information hiding.

What is the Atbash Cipher? - Ancient Encryption Explained

Atbash is a monoalphabetic substitution cipher that works by simply reversing the alphabet. The first letter becomes the last letter, the second becomes the second-to-last, and so on. This ancient encryption technique is elegantly simple yet historically significant, making it perfect for cryptography education and beginners learning encryption.

The Name's Origin

The word "Atbash" itself demonstrates the cipher's principle. It combines:

  • Aleph (א) - first letter of Hebrew alphabet
  • Tav (ת) - last letter of Hebrew alphabet
  • Beth (ב) - second letter of Hebrew alphabet
  • Shin (ש) - second-to-last letter of Hebrew alphabet

Taking the first letters: A-T-B-SH = Atbash

How the Atbash Cipher Works

Basic Algorithm

The transformation is straightforward:

Original:  A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Atbash:    Z Y X W V U T S R Q P O N M L K J I H G F E D C B A

Each letter maps to its mirror position:

  • Position formula: For letter at position i, encrypted position = alphabet_length - 1 - i
  • English: A (position 0) → Z (position 25), B (position 1) → Y (position 24)

Free Online Atbash Cipher Tool - Encrypt & Decrypt Text

How to Use Our Atbash Encoder/Decoder

Our free online Atbash cipher tool preserves the traditional algorithm while adding modern conveniences for easy text encryption and message decoding:

  1. Bidirectional Text Processing: Since Atbash is self-inverse cipher, the same process encrypts and decrypts messages
  2. Real-time Encryption: See instant results as you type - perfect for quick encoding
  3. Multiple Character Sets: Extend beyond letters to include numbers and symbols encryption
  4. Educational Tool: Perfect for learning cryptography and understanding ancient codes
Character Set Support
Letters (Always Active)
Plaintext:  HELLO WORLD
Ciphertext: SVOOL DLIOW
Numbers (Optional)

When enabled, numbers reverse too:

Original: 0 1 2 3 4 5 6 7 8 9
Atbash:   9 8 7 6 5 4 3 2 1 0

Example:
Plaintext:  SECRET123
Ciphertext: HVXIVG876
Special Characters (Optional)

Punctuation marks also get the mirror treatment:

Original: ! @ # $ % ^ & * ( )
Atbash:   ) ( * & ^ % $ # @ !

Example:
Plaintext:  HELLO, WORLD!
Ciphertext: SVOOL, DLIOW)
Character Mapping Display

Our tool shows you exactly how each character transforms, making the cipher's logic transparent and educational.

Atbash Cipher Examples and Practice - Learn to Encrypt Messages

Simple Word Encryption Examples
CAT → XZG          (Pet animals)
DOG → WLT          (Common pets)
LOVE → OLEZ        (Emotions)
PEACE → KVZXV      (Abstract concepts)
HELLO → SVOOL      (Greetings)
SECRET → HVXIVG    (Hidden messages)
Complete Sentence Encoding
Plaintext:  THE QUICK BROWN FOX JUMPS
Ciphertext: GSV JFRXP YILDM ULC QFNKH

Plaintext:  MEET AT DAWN FOR SECRET
Ciphertext: NVVG ZG WZME ULI HVXIVG

Plaintext:  ANCIENT HEBREW CIPHER CODE
Ciphertext: ZMXRVMG SVYIVD XRKSVI XLWV

Why Learn Atbash? - Educational and Cultural Value

Despite its cryptographic weaknesses, Atbash remains valuable for:

  • Cryptography Education: Teaching basic encryption principles to beginners
  • Historical Understanding: Connecting to ancient encryption history
  • Puzzle and Game Applications: Recreational cryptography and cipher puzzles
  • Cultural and Religious Studies: Understanding biblical codes and historical texts
  • Academic Research: Studying early cryptographic methods and ancient communication

Interesting Facts

  • Age: Over 2,500 years old, making it one of humanity's oldest ciphers
  • Self-inverse: Encrypting an already encrypted message decrypts it
  • Zero key: No secret information needed beyond knowing the method
  • Universal: Works with any alphabet that has a defined order
  • Speed: Can be done entirely by hand with no tools

If you're interested in Atbash encryption, explore these related cipher techniques:

  • Caesar Cipher: Simple shift-based substitution cipher - perfect for beginners learning cryptography
  • Caesar Cipher Auto Decoder: Automatically decode encrypted messages with all possible shifts
  • ROT13: Modern 13-position rotation cipher - popular in online forums and a special case of Caesar cipher
  • Simple Substitution Cipher: Keyword-based alphabet scrambling - more secure variation of monoalphabetic ciphers
  • Affine Cipher: Mathematical substitution formulas - combines multiplication and addition, includes Atbash as special case
  • Vigenère Cipher: Polyalphabetic encryption - multiple alphabet substitution for enhanced security
  • Playfair Cipher: Digraph substitution - encrypts letter pairs instead of single letters

Further Reading

Explore the Atbash cipher's fascinating origins and deeper cryptanalysis: