Private Function Evaluation Using Intel's SGX

Abstract

Private Function Evaluation (PFE) is the problem of evalu- ating one party's private data using a private function owned by another party. Several techniques were presented to tackle PFE by running universal circuits in secure multi-party computation and more recently by hiding the circuit's topology and the gate's functionalities. These solutions however, are not efficient enough for practical use, hence there remains a need for more efficient techniques. This work looks at utilizing the Intel Software Guard Extensions platform (SGX) to provide a more practical solution for PFE while the privacy of the data and the function are both kept protected. Our solution carefully avoids the pitfalls of side channel attacks on SGX. We present solutions for two different scenarios: the first is with the function's owner having SGX enabled and the other is with a third party (other than data owner and function owner) having SGX. Our results show a clear expected advantage in term of time consumption for the first case over the second. Investigating the slowdown in the second case lead to the garbling time which constitutes more than 60% of the consumed time. Both solutions clearly outperform FairplayPF in our tests.