International Association
for Cryptologic Research

Post-Quantum Cryptography (PQC) was proposed due to the potential threats quantum computer attacks against conventional public key cryptosystems, and four PQC algorithms besides CRYSTALS-Dilithium (Dilithium for short) have so far been selected for NIST standardization. However, the selected algorithms are still vulnerable to side-channel attacks in practice, and their physical security need to be further evaluated. This study introduces two efficient power analysis attacks, the optimized fast two-stage approach and the single-bit approach, aimed at reducing the key guess space in NTT polynomial multiplication on an STM32F405 device (ARM Cortex-M4 core). Our findings reveal that the optimized approach outperforms the conservative approach and the fast two-stage approach proposed in ICCD 2021 by factors of 519 and 88, respectively. Similarly, the single-bit approach demonstrates speedups of 365 and 62 times compared to these two approaches, respectively.