Smart and Vercauteren proposed a homomorphic encryption scheme (PKC 2010) following Gentry's principles. Though their scheme can achieve fully homomorphism theoretically, they admitted that "for practical values of n our scheme cannot be made fully homomorphic" (p. 16).
However, perhaps the
only (see update 1 below) public fully (not somewhat) homomorphic encryption implementation libScarab, is claimed to be using the SV scheme. The authors of that library also have a paper "POSTER: An Implementation of the Fully Homomorphic Smart-Vercauteren Crypto-System" (CCS'11) about their implementation.
There are several parameters chosen differently in the latter paper from the original paper, maybe for achieving full homomorphism. But they did not explain the security of their choices, and I cannot figure out it by myself.
So my question is, can libScarab be viewed as a serious secure FHE implementation?
Update 1 (18 Nov 2015)
I've found there are two other public fully homomorphic encryption (including bootstrapping) libraries (HELib and FHEW) released by illustrious cryptologists Shai Halevi / Victor Shoup and Leo Ducas / Daniele Micciancio. Both are slower than libScarab, but I think they supply more security.