Affine cipher tool
An affine cipher is a type of monoalphabetic substitution cipher. It converts each letter to a number (A=0, Z=25), applies the formula E(x) = (ax + b) (mod 26), and changes the result back to a letter. The key uses two numbers, a and b.
Enter the encrypted text into the first box, then select your two keys and click ‘Decrypt’ to see the resulting change.