Fully encrypted high-speed microprocessor architecture: the secret computer in simulation

摘要

The architecture of an encrypted high-performance microprocessor designed on the principle that a nonstandard arithmetic generates encrypted processor states is described here. Data in registers, in memory and on buses exists in encrypted form. Any block encryption is feasible, in principle. The processor is (initially) intended for cloud-based remote computation. An encrypted version of the standard OpenRISC instruction set is understood by the processor. It is proved here, for programs written in a minimal subset of instructions, that the platform is secure against 'Iago' attacks by the privileged operator or a subverted operating system, which cannot decrypt the program output, nor change the program's output to a particular value of their choosing. Performance measures from cycle-accurate behavioural simulation of the platform are given for 64-bit RC2 (symmetric, keyed) and 72-bit Paillier (asymmetric, additively homomorphic, no key in-processor) encryptions. Measurements are centred on a nominal 1 GHz clock with 3 ns cache and 15 ns memory latency, which is conservative with respect to available technology.