Integer arithmetic over ciphertext and homomorphic data aggregation

Typical encryptions cannot allow computations on the ciphertext-a conflict between exploiting the power of cloud computing and protecting user privacy. One candidate solution to this problem is fully homomorphic encryption (FHE), which will enable cloud servers to perform complicated computation on behalf of clients without clients´ private information being revealed. But FHE is generally considered very computationintensive. We implement integer arithmetic, which is the basis of many data aggregation functionalities, over FHE for the first time and evaluate the performance from a practical perspective. Our work will provide some reference on the application of FHE to the cloud.