In-depth Correlation Power Analysis Attacks on a Hardware Implementation of CRYSTALS-Dilithium

During the standardisation process of post-quantum cryptography, NIST encourages research on side-channel analysis for candidate schemes. As the recommended lattice signature scheme, CRYSTALS-Dilithium, when implemented on hardware, has seen limited research on side-channel analysis, and current attacks are incomplete or requires a substantial quantity of traces. Therefore, we conducted a more complete analysis to investigate the leakage of an FPGA implementation of CRYSTALS-Dilithium using the Correlation Power Analysis (CPA) method, where with a minimum of 70,000 traces partial private key coefficients can be recovered. Furthermore, we optimise the attack by extracting Point-of-Interests using known information due to parallelism (named CPA-PoI) and by iteratively utilising parallel leakages (named CPA-ITR). Our experimental results show that CPA-PoI reduces the number of traces by up to 16.67%, CPA-ITR by up to 25%, and both increase the number of recovered key coefficients by up to 55.17% and 93.10% using the same number of traces. They outperfom the CPA method. As a result, it suggests that the FPGA implementation of CRYSTALS-Dilithium is more vulnerable than thought before to side-channel analysis.