Leaky McEliece: Secret Key Recovery From Highly Erroneous Side-Channel Information

The McEliece cryptosystem is a strong contender for post-quantum schemes, including key encapsulation for confidentiality of key exchanges in network protocols. A McEliece secret key is a structured parity check matrix that is transformed via Gaussian elimination into an unstructured public key. We...

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Main Authors: Marcus Brinkmann, Chitchanok Chuengsatiansup, Alexander May, Julian Nowakowski, Yuval Yarom
Format: Article
Language:English
Published: Ruhr-Universität Bochum 2025-03-01
Series:Transactions on Cryptographic Hardware and Embedded Systems
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Online Access:https://tches.iacr.org/index.php/TCHES/article/view/12043
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author Marcus Brinkmann
Chitchanok Chuengsatiansup
Alexander May
Julian Nowakowski
Yuval Yarom
author_facet Marcus Brinkmann
Chitchanok Chuengsatiansup
Alexander May
Julian Nowakowski
Yuval Yarom
author_sort Marcus Brinkmann
collection DOAJ
description The McEliece cryptosystem is a strong contender for post-quantum schemes, including key encapsulation for confidentiality of key exchanges in network protocols. A McEliece secret key is a structured parity check matrix that is transformed via Gaussian elimination into an unstructured public key. We show that this transformation is highly critical with respect to side-channel leakage. We assume leakage of the elementary row operations during Gaussian elimination, motivated by McEliece implementations in the cryptographic libraries Classic McEliece and Botan. We propose a novel decoding algorithm to reconstruct a secret key from its public key with information from a Gaussian transformation leak. Even if the obtained side-channel leakage is extremely noisy, i.e., each bit is flipped with probability as high as r ≈ 0.4, we succeed to recover the secret key in a matter of minutes for all proposed (Classic) McEliece instantiations. Remarkably, for high-security McEliece parameters, our attack is more powerful in the sense that it can tolerate even larger r . We demonstrate our attack on the constant-time reference implementation of Classic McEliece in a single-trace setting, using an STM32L592 ARM processor. Our result stresses the necessity of properly protecting highly structured code-based schemes such as McEliece against side-channel leakage.
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issn 2569-2925
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publishDate 2025-03-01
publisher Ruhr-Universität Bochum
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series Transactions on Cryptographic Hardware and Embedded Systems
spelling doaj-art-6fbb80c435a74aada91a7bece212df052025-08-20T01:57:43ZengRuhr-Universität BochumTransactions on Cryptographic Hardware and Embedded Systems2569-29252025-03-012025210.46586/tches.v2025.i2.94-125Leaky McEliece: Secret Key Recovery From Highly Erroneous Side-Channel InformationMarcus Brinkmann0https://orcid.org/0000-0001-5649-6357Chitchanok Chuengsatiansup1Alexander May2Julian Nowakowski3Yuval Yarom4Ruhr University Bochum, Bochum, GermanyThe University of Klagenfurt, Klagenfurt, AustriaRuhr University Bochum, Bochum, GermanyRuhr University Bochum, Bochum, GermanyRuhr University Bochum, Bochum, Germany The McEliece cryptosystem is a strong contender for post-quantum schemes, including key encapsulation for confidentiality of key exchanges in network protocols. A McEliece secret key is a structured parity check matrix that is transformed via Gaussian elimination into an unstructured public key. We show that this transformation is highly critical with respect to side-channel leakage. We assume leakage of the elementary row operations during Gaussian elimination, motivated by McEliece implementations in the cryptographic libraries Classic McEliece and Botan. We propose a novel decoding algorithm to reconstruct a secret key from its public key with information from a Gaussian transformation leak. Even if the obtained side-channel leakage is extremely noisy, i.e., each bit is flipped with probability as high as r ≈ 0.4, we succeed to recover the secret key in a matter of minutes for all proposed (Classic) McEliece instantiations. Remarkably, for high-security McEliece parameters, our attack is more powerful in the sense that it can tolerate even larger r . We demonstrate our attack on the constant-time reference implementation of Classic McEliece in a single-trace setting, using an STM32L592 ARM processor. Our result stresses the necessity of properly protecting highly structured code-based schemes such as McEliece against side-channel leakage. https://tches.iacr.org/index.php/TCHES/article/view/12043McElieceGaussian eliminationSide-channel leakageKey recovery with hints
spellingShingle Marcus Brinkmann
Chitchanok Chuengsatiansup
Alexander May
Julian Nowakowski
Yuval Yarom
Leaky McEliece: Secret Key Recovery From Highly Erroneous Side-Channel Information
Transactions on Cryptographic Hardware and Embedded Systems
McEliece
Gaussian elimination
Side-channel leakage
Key recovery with hints
title Leaky McEliece: Secret Key Recovery From Highly Erroneous Side-Channel Information
title_full Leaky McEliece: Secret Key Recovery From Highly Erroneous Side-Channel Information
title_fullStr Leaky McEliece: Secret Key Recovery From Highly Erroneous Side-Channel Information
title_full_unstemmed Leaky McEliece: Secret Key Recovery From Highly Erroneous Side-Channel Information
title_short Leaky McEliece: Secret Key Recovery From Highly Erroneous Side-Channel Information
title_sort leaky mceliece secret key recovery from highly erroneous side channel information
topic McEliece
Gaussian elimination
Side-channel leakage
Key recovery with hints
url https://tches.iacr.org/index.php/TCHES/article/view/12043
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AT alexandermay leakymceliecesecretkeyrecoveryfromhighlyerroneoussidechannelinformation
AT juliannowakowski leakymceliecesecretkeyrecoveryfromhighlyerroneoussidechannelinformation
AT yuvalyarom leakymceliecesecretkeyrecoveryfromhighlyerroneoussidechannelinformation