Partial Number Theoretic Transform Masking in Post Quantum Cryptography Hardware: A Security Margin Analysis

Computer Science > Cryptography and Security [Submitted on 4 Apr 2026] Partial Number Theoretic Transform Masking in Post Quantum Cryptography Hardware: A Security Margin Analysis Ray Iskander, Khaled Kirah Adams Bridge, a hardware accelerator for ML-DSA and ML-KEM designed for the Caliptra root of trust, masks 1 of its Inverse Number Theoretic Transform (INTT) layers and relies on shuffling for the remainder, claiming per-butterfly Correlation Power Analysis (CPA) complexities of 2^46 (ML-DSA) and 2^96 (ML-KEM). We evaluate these claims against published side-channel literature across seven analysis tracks with confidence-rated evidence. Register-Transfer Level (RTL) analysis confirms that the design's Random Start Index (RSI) shuffling provides 6 bits of entropy per layer (64 orderings) rather than the 296 bits of a full random permutation assumed in its scaling argument, with effective margins below the designers' estimates. A soft-analytical attack pipeline demonstrates a 37-bit enumeration reduction, independent of Belief Propagation (BP) gains, quantifying the attack-model gap without achieving key recovery. Full-scale BP on the complete INTT factor graph achieves 100% coefficient recovery over the single-layer baseline, resolving whether BP gains scale to production-size Number Theoretic Transform (NTT) structures. A genie-aided information-theoretic bound shows observations contain sufficient mutual information for full recovery at SNRxN as low as 15. Layer-ablation analysis identifies four necessary conditions governing BP convergence. Observation topology, not count, determines recovery: 4 evenly spread layers achieve 100% while 4 consecutive layers achieve 0%, yielding a practical countermeasure design tool. Strategic masking of 3 consecutive mid-layers (43% overhead vs. full masking) creates an unrecoverable gap that defeats soft-analytical attacks. We contribute a reusable security margin audit methodology combining RTL verification, epistemic confidence tagging, sensitivity-scenario analysis, and experimental validation applicable to any partially masked NTT accelerator. Comments: 38 pages, 2 figures Subjects: Cryptography and Security (cs.CR) Cite as: arXiv:2604.03813 [cs.CR]   (or arXiv:2604.03813v1 [cs.CR] for this version)   https://doi.org/10.48550/arXiv.2604.03813 Focus to learn more Submission history From: Khaled Kirah Dr [view email] [v1] Sat, 4 Apr 2026 17:38:34 UTC (1,212 KB) Access Paper: view license Current browse context: cs.CR < prev   |   next > new | recent | 2026-04 Change to browse by: cs References & Citations NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)