Many ciphers are automated and rely on a mathematical encryption algorithm.
One common class of letter shift ciphers is known as the affine shift cipher. It
uses the form x -> 3x + 5 where the numbers can vary. The aim is that by
knowing the letter substitutions for 2 letters then we can solve the 2
simultaneous equations. However, this means division in modulus maths - which
may not be possible if a multiplicative inverse cannot be found. So you may need
to try a few characters before this works.

The box below contains example encrypted text. You can paste the text that
you want to decipher over this example text. Then fill in your replacement
letters.