Atbash & Affine Cipher Decoder
Reciprocal alphabet substitution and modular arithmetic Affine cipher encoder/decoder.
Execution runs 100% locally inside the browser sandbox using HTML5 Canvas, Web Cryptography Subtle API, and Web Workers. No data is ever transmitted across the network.
Zero network latency. Operates completely offline with zero dependencies on third-party backend servers or cloud services.
Built according to official RFC specifications, cryptographic test vectors, and enterprise-grade data transformation standards.
How to Use Atbash & Affine Cipher Decoder
Choose Atbash (A ↔ Z), Affine Encrypt, or Affine Decrypt.
For Affine ciphers, select coprime slope key (a) and shift value (b).
Copy the transformed cipher text or plain text.
Frequently Asked Questions
What is an Atbash cipher?
The Atbash cipher is a monoalphabetic substitution cipher originally developed for the Hebrew alphabet where the first letter maps to the last (A ↔ Z, B ↔ Y).
Why must key 'a' be coprime to 26 in an Affine cipher?
Key 'a' must share no common factors with 26 so that a unique modular multiplicative inverse exists for unambiguous decryption.
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