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A Side-Channel Assisted Cryptanalytic Attack Against QcBits

Abstract : QcBits is a code-based public key algorithm based on a problem thought to be resistant to quantum computer attacks. It is a constant-time implementation for a quasi-cyclic moderate density parity check (QC-MDPC) Niederreiter encryption scheme, and has excellent performance and small key sizes. In this paper, we present a key recovery attack against QcBits. We first used differential power analysis (DPA) against the syndrome computation of the decoding algorithm to recover partial information about one half of the private key. We then used the recovered information to set up a system of noisy binary linear equations. Solving this system of equations gave us the entire key. Finally, we propose a simple but effective countermeasure against the power analysis used during the syndrome calculation.
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Contributor : Mélissa Rossi <>
Submitted on : Wednesday, October 11, 2017 - 11:06:39 AM
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Mélissa Rossi, Mike Hamburg, Michael Hutter, Mark Marson. A Side-Channel Assisted Cryptanalytic Attack Against QcBits. CHES 2017 - Conference on Cryptographic Hardware and Embedded Systems, Sep 2017, Taipei, Taiwan. pp.22, ⟨10.1007/978-3-319-66787-4_1⟩. ⟨hal-01614569⟩



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