  Recently, Lu et al. have proposed two image search schemes based on additive
homomorphic encryption [IEEE Access, 2 (2014), 125-141]. We remark that both
two schemes are flawed because: (1) the first scheme does not make use of the
additive homomorphic property at all; (2) the additive homomorphic encryption
in the second scheme is unnecessary and can be replaced by a more efficient
symmetric key encryption.
