PREFHE, PREFHE-AES and PREFHE-SGX: Secure Multiparty Computation Protocols from Fully Homomorphic Encryption and Proxy ReEncryption with AES and Intel SGX

We build our secure multiparty computation (MPC) protocols on top of the fully homomorphic encryption (FHE) scheme, BFVrns, and augment it with Proxy Re-Encryption (PRE). We offer three distinct secure MPC protocols that make use of the Advanced Encryption Standard (AES) and Intel Software Guardian Extension (SGX). The PREFHE protocol is based on FHE and PRE that offers a reasonable computational time of milliseconds or seconds, depending on the function computed jointly on the parties’ encrypted data. It offers 4 rounds and a communication cost that only depends on the parties’ ciphertext size. PREFHE-AES employs AES-128 encryption, which reduces the cost of communication to bits rather than kilobytes or megabytes while maintaining the same number of rounds as PREFHE. PREFHE-SGX is another novel approach that reduces the number of rounds from 4 to 3 by utilizing only one untrusted server. Additionally, it delivers a reasonable level of performance that is applicable to real-world use cases. We pioneer the use of SGX and FHE in secure MPC protocols, resulting in reduced number of rounds. In the protocols, after parties send their encrypted data to the server, they are not required to be online that improves practicality in the protocols. Additionally, the parties are not required to collaborate on any computations during the encryption and decryption phases that makes our protocols more efficient than other proposed protocols.