Cryptology ePrint Archive: Report 2020/910

A Power Side-Channel Attack on the CCA2-Secure HQC KEM

Thomas Schamberger and Julian Renner and Georg Sigl and Antonia Wachter-Zeh

Abstract: The Hamming Quasi-Cyclic (HQC) proposal is a promising candidate in the second round of the NIST Post-Quantum cryptography Standardization project. It features small public key sizes, precise estimation of its decryption failure rates and contrary to most of the code-based systems, its security does not rely on hiding the structure of an error-correcting code. In this paper, we propose the first power side-channel attack on the Key Encapsulation Mechanism (KEM) version of HQC. Our attack utilizes a power side-channel to build an oracle that outputs whether the BCH decoder in HQC's decryption algorithm corrects an error for a chosen ciphertext. Based on the decoding algorithm applied in HQC, it is shown how to design queries such that the output of the oracle allows to retrieve a large part of the secret key. The remaining part of the key can then be determined by an algorithm based on linear algebra. It is shown in experiments that less than 10000 measurements are sufficient to successfully mount the attack on the HQC reference implementation running on an ARM Cortex-M4 microcontroller.

Category / Keywords: public-key cryptography / Error Correction, HQC, Post-Quantum Cryptography, Power Analysis, Side-Channel Analysis

Date: received 20 Jul 2020

Contact author: t schamberger at tum de, julian renner@tum de

Available format(s): PDF | BibTeX Citation

Version: 20200723:005948 (All versions of this report)

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