Paper 2016/1193

Superscalar Encrypted RISC: Measure of a Secret Computer

Peter T. Breuer and Jonathan P. Bowen

Abstract

It suffices to change the arithmetic embedded in a processor in order to cause data to remain in encrypted form throughout. The theory has been embodied in a prototype design for a superscalar pipelined general purpose processor that `works encrypted', a new approach to encrypted computation. The prototype runs encrypted machine code on encrypted data in registers and memory and on buses. The aim is to protect user data against the operator, and so-called `Iago' attacks in general, for those computing paradigms that entail trust in data-oriented computation in remote locations, overseen by untrusted operators, or embedded unattended. The architecture is 32-bit OpenRISC, admitting any block cipher compatible with the physical word size chosen for implementation. We are reporting performance from cycle-accurate behavioural simulations of the design running AES-128 (symmetric, keyed; the US Advanced Encryption Standard) and Paillier-72 (asymmetric, additively homomorphic, no key in-processor) encryptions in a 128-bit word, and RC2-64 encryption (symmetric, keyed) in a 64-bit word.

Note: Update for resubmission.