  Fully homomorphic encryption is a promising crypto primitive to encrypt your
data while allowing others to compute on the encrypted data. But there are many
well-known problems with fully homomorphic encryption such as CCA security and
circuit privacy problem. Despite these problems, there are still many companies
are currently using or preparing to use fully homomorphic encryption to build
data security applications. It seems that the full homomorphic encryption is
very close to practicality and these problems can be easily mitigated in
implementation. Although the those problems are well known in theory, there is
no public discussion of their actual impact on real application. Our research
shows that there are many security pitfalls in fully homomorphic encryption
from the perspective of practical application. The security problems of a fully
homomorphic encryption in a real application is more severe than imagined. In
this paper, we will take Microsoft SEAL as an examples to introduce the
security pitfalls of fully homomorphic encryption from the perspective of
implementation and practical application
