Homomorphic encryption is malleable. But once noise is added, there is no way to exploit malleability. The big challenge in creation of a fully homomorphic enc

Homomorphic encryption is malleable. But once noise is added, there is no way to exploit malleability. The big challenge in creation of a fully homomorphic encryption scheme was to make it able to cope with added randomness. This problem remained unsolved starting from 1978 when Rivest, Shamir and Adleman noted probable possibility of such scheme up until 2008 when Craig Gentry came up with solution in his PhD thesis. Gentry's work is a fascinating read by they way. In other words, homomorphic encryption has the same security guarantees as a conventional crypto.