Efficient and Composable Masked AES S-Box Designs Using Optimized Inverters

Hardware implementations of cryptographic algorithms are susceptible to power analysis attacks, allowing attackers to break the otherwise strong security guarantees. A theoretically sound countermeasure against such attacks is masking, where all key- and data-dependent intermediate values in the co...

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Main Authors: Vedad Hadžic, Roderick Bloem
Format: Article
Language:English
Published: Ruhr-Universität Bochum 2024-12-01
Series:Transactions on Cryptographic Hardware and Embedded Systems
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Online Access:https://tosc.iacr.org/index.php/TCHES/article/view/11942
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author Vedad Hadžic
Roderick Bloem
author_facet Vedad Hadžic
Roderick Bloem
author_sort Vedad Hadžic
collection DOAJ
description Hardware implementations of cryptographic algorithms are susceptible to power analysis attacks, allowing attackers to break the otherwise strong security guarantees. A theoretically sound countermeasure against such attacks is masking, where all key- and data-dependent intermediate values in the computation are split into so-called shares, requiring an attacker to learn all of them before recovering the secret key. Masking a cryptographic hardware design against power analysis attacks incurs large area and latency overheads due to their nonlinear components, especially when implemented using composable masking schemes. These overheads disproportionately affect ciphers with highly nonlinear monolithic S-Boxes like the Advanced Encryption Standard (AES). The masking of the AES S-Box is well studied, and most implementations use Canright’s F28 inverter design that decomposes operations in a larger field into a combination of multiplications, additions and inversions in a smaller field. While remarkable, Canright’s inverter design has a sub-optimal multiplicative depth, and can thus not take full advantage of recent developments in low-latency composable masking schemes. In this paper, we present a F28 inverter that achieves the optimal multiplicative depth of three, and use it to construct a more efficient trivially composable masked implementation of the AES S-Box. Moreover, we present HPC3.1, a better low-latency multiplication gadget that works in all finite fields Fpn, and a randomness reuse strategy for both HPC1 and HPC3.1 gadgets that preserves side-channel security. Orthogonally, we also propose an improved bit-level implementation of the F24 inverter for more efficient masked S-Box designs based on Canright’s original F28 inverter. We develop, functionally test, and formally verify the trivially composable side-channel security of all masked AES S-Box designs. Our evaluation shows that the designs outperform or match the state-of-the-art in terms of latency, randomness use and area cost.
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spelling doaj-art-7f9ec9d69797431d98d0d83fd56664142025-08-20T02:38:33ZengRuhr-Universität BochumTransactions on Cryptographic Hardware and Embedded Systems2569-29252024-12-012025110.46586/tches.v2025.i1.656-683Efficient and Composable Masked AES S-Box Designs Using Optimized InvertersVedad Hadžic0Roderick Bloem1Graz University of Technology, Graz, AustriaGraz University of Technology, Graz, Austria Hardware implementations of cryptographic algorithms are susceptible to power analysis attacks, allowing attackers to break the otherwise strong security guarantees. A theoretically sound countermeasure against such attacks is masking, where all key- and data-dependent intermediate values in the computation are split into so-called shares, requiring an attacker to learn all of them before recovering the secret key. Masking a cryptographic hardware design against power analysis attacks incurs large area and latency overheads due to their nonlinear components, especially when implemented using composable masking schemes. These overheads disproportionately affect ciphers with highly nonlinear monolithic S-Boxes like the Advanced Encryption Standard (AES). The masking of the AES S-Box is well studied, and most implementations use Canright’s F28 inverter design that decomposes operations in a larger field into a combination of multiplications, additions and inversions in a smaller field. While remarkable, Canright’s inverter design has a sub-optimal multiplicative depth, and can thus not take full advantage of recent developments in low-latency composable masking schemes. In this paper, we present a F28 inverter that achieves the optimal multiplicative depth of three, and use it to construct a more efficient trivially composable masked implementation of the AES S-Box. Moreover, we present HPC3.1, a better low-latency multiplication gadget that works in all finite fields Fpn, and a randomness reuse strategy for both HPC1 and HPC3.1 gadgets that preserves side-channel security. Orthogonally, we also propose an improved bit-level implementation of the F24 inverter for more efficient masked S-Box designs based on Canright’s original F28 inverter. We develop, functionally test, and formally verify the trivially composable side-channel security of all masked AES S-Box designs. Our evaluation shows that the designs outperform or match the state-of-the-art in terms of latency, randomness use and area cost. https://tosc.iacr.org/index.php/TCHES/article/view/11942AESMaskingPINILow-latencyMask Reuse
spellingShingle Vedad Hadžic
Roderick Bloem
Efficient and Composable Masked AES S-Box Designs Using Optimized Inverters
Transactions on Cryptographic Hardware and Embedded Systems
AES
Masking
PINI
Low-latency
Mask Reuse
title Efficient and Composable Masked AES S-Box Designs Using Optimized Inverters
title_full Efficient and Composable Masked AES S-Box Designs Using Optimized Inverters
title_fullStr Efficient and Composable Masked AES S-Box Designs Using Optimized Inverters
title_full_unstemmed Efficient and Composable Masked AES S-Box Designs Using Optimized Inverters
title_short Efficient and Composable Masked AES S-Box Designs Using Optimized Inverters
title_sort efficient and composable masked aes s box designs using optimized inverters
topic AES
Masking
PINI
Low-latency
Mask Reuse
url https://tosc.iacr.org/index.php/TCHES/article/view/11942
work_keys_str_mv AT vedadhadzic efficientandcomposablemaskedaessboxdesignsusingoptimizedinverters
AT roderickbloem efficientandcomposablemaskedaessboxdesignsusingoptimizedinverters