Optimizing fully homomorphic encryption

Abstract

Fully homomorphic encryption (FHE) presents the possibility of removing the need to trust cloud providers with plaintext data. We present two new FHE scheme variants of BGV'12, both of which remove the need for key switching after a ciphertext multiplication, overall halving the runtime of bootstrapping. We also present multiple implementations of 32-bit integer addition evaluation, the fastest of which spends 16 seconds computing the addition circuit and 278 seconds bootstrapping. We nd that bootstrapping consumes approximately 90% of the computation time for integer addition and secure parameter settings are currently bottlenecked by the memory size of commodity hardware.