I am also working on the same system (and having a similar problem). From my experience, I advise you to check followings:
Does your parameter set allow you to recover result of a homomorphic multiplication? As you know, if noise growth in multiplication operation is not low enough, your decryption operation may fail (so you got a polynomial with randomly ...
Does the problem of noise growth exist in the Paillier homomorphic scheme ?
No, it does not. Unlike Lattice-based schemes, you can do as many homomorphic additions as you want in Paillier (without doing anything like a "reboot"), and it's never a problem.
I am simplifying greatly, maybe someone else can provide a
more formal answer.
I see that homomorphic encryption works with only numeric data.
There are many ways to encode strings into integers,
you can encode a string into bytes and then translate these bytes to an integer.
I have read that homomorphic has scalability issues as it creates a 100x ...