# Do Partially Homomorphic Encryption schemes also suffer from noise overflow?

Do PHE schemes in general also suffer from noise overflow problem?

• Very imprecisely, in FHE, the noise and the plaintext are in the same space. When evaluating a function $f$ homomorphically, you are actually computing $f(plaintext + noise)$. The noise can be eliminated from the result only if it does not exceed a certain modulus, e.g. see here crypto.stackexchange.com/questions/35150/…. In PHE, the problem does not exist. The plaintext is always being evaluated in its own space. Although PHE also uses random numbers in encryption, the random numbers don't interfere with the plaintext in the homomorphic computation. Aug 20 '19 at 12:38