Paper 2024/533

HyCaMi: High-Level Synthesis for Cache Side-Channel Mitigation

Abstract

Cache side-channels are a major threat to cryptographic implementations, particularly block ciphers. Traditional manual hardening methods transform block ciphers into Boolean circuits, a practice refined since the late 90s. The only existing automatic approach based on Boolean circuits achieves security but suffers from performance issues. This paper examines the use of Lookup Tables (LUTs) for automatic hardening of block ciphers against cache side-channel attacks. We present a novel method combining LUT-based synthesis with quantitative static analysis in our HyCaMi framework. Applied to seven block cipher implementations, HyCaMi shows significant improvement in efficiency, being 9.5$\times$ more efficient than previous methods, while effectively protecting against cache side-channel attacks. Additionally, for the first time, we explore balancing speed with security by adjusting LUT sizes, providing faster performance with slightly reduced leakage guarantees, suitable for scenarios where absolute security and speed must be balanced.

Note: Are programs automatically hardened using LUTs more efficient in performance compared to those automatically hardened with Boolean circuits, while retaining the same cache side-channel security? To address this question, we introduce HyCaMi, an innovative approach that merges LUT synthesis with quantitative side-channel analysis.