A First Practical Fully Homomorphic Crypto-Processor Design: The Secret Computer is Nearly Here

TL;DR

This paper presents a prototype of a fully homomorphic crypto-processor capable of executing encrypted machine code securely, demonstrating practical performance and potential for secure remote computing applications.

Contribution

The authors develop and evaluate the first working pseudo-homomorphic crypto-processor with a dual-mode architecture supporting encrypted execution at near-acceptable speeds.

Findings

Encrypted mode runs at 60-70% of unencrypted speed

Processor executes encrypted instructions every 1.67-1.8 cycles

Prototype demonstrates practical feasibility of secure homomorphic processing

Abstract

Following a sequence of hardware designs for a fully homomorphic crypto-processor - a general purpose processor that natively runs encrypted machine code on encrypted data in registers and memory, resulting in encrypted machine states - proposed by the authors in 2014, we discuss a working prototype of the first of those, a so-called `pseudo-homomorphic' design. This processor is in principle safe against physical or software-based attacks by the owner/operator of the processor on user processes running in it. The processor is intended as a more secure option for those emerging computing paradigms that require trust to be placed in computations carried out in remote locations or overseen by untrusted operators. The prototype has a single-pipeline superscalar architecture that runs OpenRISC standard machine code in two distinct modes. The processor runs in the encrypted mode (the unprivileged, `user' mode, with a long pipeline) at 60-70% of the speed in the unencrypted mode (the privileged, `supervisor' mode, with a short pipeline), emitting a completed encrypted instruction every 1.67-1.8 cycles on average in real trials.