Affine Cipher
Encrypt and decrypt with E(x) = (a·x + b) mod 26.
Encoded
Rclla oaplx
Affine cipher: E(x) = (a·x + b) mod 26. The multiplier a must be coprime with 26, leaving 12 valid values. Decryption uses the modular inverse of a. Caesar is a special case where a = 1.
About
The Affine cipher generalizes Caesar by adding a multiplier. Pick a (must be coprime to 26, leaving 12 valid values) and b (any shift 0–25). Decryption uses the modular inverse of a.
How to use
- Pick a and b.
- Type your text.
- Toggle encode/decode.
FAQ
How is this different from Caesar?+
Caesar is the special case a = 1. Affine adds a multiplier, giving 312 possible keys (12 × 26) instead of 26. Still trivially breakable by frequency analysis.