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: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Ruhr-Universität Bochum
2025-03-01
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| Series: | Transactions on Cryptographic Hardware and Embedded Systems |
| Subjects: | |
| Online Access: | https://tches.iacr.org/index.php/TCHES/article/view/12043 |
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| Summary: | 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 |