In LTV-FHE, section 3.3.2 Formal description, a ciphertext looks like this $c=hs+2e+b = (2g/f)s+2e+b$, where $h = 2g/f$ is the public key, $f$ is the secret key, $g, s$ and $e$ are chosen randomly, and $b$ is the bit to be encrypted.
Following the equation $c = (2g/f)s+2e+b$, the bit $b$ can be obtained easily performing a modulo 2 operation for a ciphertext.
What is the hardness that protects against this simple modulo reduction ?