Paper 2025/1358

Domain-Oriented Masking Revisited: More Efficient AES Implementations with Arbitrary Protection Order

Abstract

Recent years have witnessed significant progress in composable masked AES designs based on Hardware Private Circuits (HPCs) under the Probe-Isolating Non-Interference (PINI) framework. However, these designs still suffer from substantial randomness requirements and area overhead at higher protection orders. In this work, we revisit Domain-Oriented Masking (DOM), originally proposed by Gross et. al. in 2016, and leverage the DOM-$dep$ and DOM-$indep$ multipliers to construct efficient AES implementations based on the Strong Non-Interference (SNI) framework. Our contributions include: 1. a comprehensive security analysis of DOM-$dep$ and DOM-$indep$, including their compositional security under the SNI framework; 2. more efficient masked AES implementations for arbitrary protection orders, reducing randomness and area overhead while maintaining latency comparable to state-of-the-art HPC3-based designs. Specifically, our masked AES implementations maintain a latency of 41 clock cycles by using the Hadzic's decomposition for $F_2^8$ inverter. When $d <= 4$, they save at least 13% in area (RNG included) and reduce latency by 19.6% compared to the smallest $d$-PINI round-based masked AES implementations provided by Cassiers et.al. (The current version focuses on the core construction and its initial evaluation. Source code has been made publicly available to facilitate verification. Further performance optimizations and theoretical generalizations are underway and will appear in an upcoming revision.)