System-Level Non-interference of Constant-Time Cryptography. Part I: Model

Abstract

This work focuses on the study of constant-time implementations; giving formal guarantees that such implementations are protected against cache-based timing attacks in virtualized platforms where their supporting operating system executes concurrently with other, potentially malicious, operating systems. We develop a model of virtualization that accounts for virtual addresses, physical and machine addresses, memory mappings, page tables, translation lookaside buffer, and cache; and provides an operational semantics for a representative set of actions, including reads and writes, allocation and deallocation, context switching, and hypercalls. We prove a non-interference result on the model that shows that an adversary cannot discover secret information using cache side-channels, from a constant-time victim.