Atbash Cipher Encoder/Decoder
Type or paste your text to encode or decode using the classic Atbash monoalphabetic substitution cipher. The tool works both ways because Atbash is its own inverse.
1. Input
We support A–Z and a–z. Non-letters (numbers, spaces, punctuation) are kept unchanged.
2. Output
Result:
3. Examples
Plain:
HELLO
Atbash:
SVOOL
Plain:
Atbash
Atbash:
Zgyzhs
How the Atbash cipher works
The Atbash cipher is one of the oldest known substitution ciphers. It simply reverses the alphabet:
Cipher: ZYXWVUTSRQPONMLKJIHGFEDCBA
So:
- A ↔ Z
- B ↔ Y
- C ↔ X
- ...
- M ↔ N
This mapping is involutive, meaning that applying it twice gets you back the original message. That’s why the same tool can be used for both encoding and decoding.
Is Atbash secure today?
No. Atbash offers zero real cryptographic security by modern standards. Anyone who knows the method or even just suspects a simple substitution can reverse it immediately. Use it for fun, puzzles, ARGs, or educational demonstrations.
Formula (LaTeX) + variables + units
','\
- No variables provided in audit spec.
- NIST — Weights and measures — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/weights-and-measures - FTC — Consumer advice — consumer.ftc.gov · Accessed 2026-01-19
https://consumer.ftc.gov/
Last code update: 2026-01-19
- Initial audit spec draft generated from HTML extraction (review required).
- Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
- Confirm sources are authoritative and relevant to the calculator methodology.