Affine cipher and shift cipher I have the following question: > An affine cipher with key $K(0,b)$ is equivalent to a shift cipher explain why I don't think this is true, and assume it is a typo, $K(1,b)$ I would agree, since this is the same as a shift cipher since: $$X=1x+b\Leftrightarrow X=x+b$$ is just a shift cipher with shift $b$.

This is definitely a typo.

The affine cipher key:$K(1,b)$ is exactly the shift cipher.