Hardware Assisted Homomorphic Encryption in a Real Time VOIP Conference Application

In this paper, a new scheme to perform a secure Voice over IP (VoIP) teleconferencing between a number of VOIP Clients is proposed. The Teleconference is done between clients regarderless of their "based on" working environment (OS (Windows, Linux, Android,..), HW (Mobile, Desktop, IP Phone, ..), ...etc). It is assumed that the SIP Server lies in an untrusted area or administered by untrusted persons. Therefore, it is highly required to prevent those persons from observing all the communications between participants and obtain unencrypted data when they have access to teleconferencing servers. An end-to-end Homomorphic Encryption (HE) is applied with the assistance of a special external Hardware appliance based on an Altera Cyclone IV 4CE115 FPGA to support the somewhat homomorphic encryption scheme. Further, this external appliance is used to boost the performance of the Homomorphic operations. Two different approaches for mixing the VOIP data streams required for the teleconference are proposed. In the first approach, the Mixing function for the encrypted VOIP data streams is performed in the SIP Server and the hardware appliance will do only the HE operations. In the second approach both the mixing function for the VOIP data streams and the HE operations are performed in the external appliance.