Signature Placement in Post-Quantum TLS Certificate Hierarchies: An Experimental Study of ML-DSA and SLH-DSA in TLS 1.3 Authentication

Computer Science > Cryptography and Security [Submitted on 7 Apr 2026] Signature Placement in Post-Quantum TLS Certificate Hierarchies: An Experimental Study of ML-DSA and SLH-DSA in TLS 1.3 Authentication José Luis Delgado Jiménez Post-quantum migration in TLS 1.3 should not be understood as a flat substitution problem in which one signature algorithm is replaced by another and deployment cost is inferred directly from primitive-level benchmarks. In certificate-based authentication, the practical effect of a signature family depends on where it appears in the certification hierarchy, how much of that hierarchy is exposed during the handshake, and how cryptographic burden is distributed across client and server roles. This paper presents a local experimental study of TLS 1.3 authentication strategies built on OpenSSL 3 and oqsprovider. Using a reproducible laboratory, it compares ML-DSA and SLH-DSA across multiple certificate placements, hierarchy depths, and key-exchange modes, including classical, hybrid, and pure post-quantum configurations. The clearest discontinuity appears when SLH-DSA is placed in the server leaf certificate. In that configuration, handshake latency and server-side compute cost increase by orders of magnitude, while strategies that confine SLH-DSA to upper trust layers and preserve ML-DSA in the interactive leaf remain within a substantially more plausible operational range. The results further show that transport size alone does not explain the heavy regime: once SLH-DSA reaches the leaf, server-side cryptographic cost becomes dominant. The paper argues that post-quantum TLS migration is best evaluated as a problem of certificate-hierarchy design, chain exposure, and cryptographic cost concentration during live authentication. Comments: 42 pages, 20 figures, 14 tables. Experimental study of post-quantum TLS 1.3 authentication with ML-DSA and SLH-DSA certificate hierarchies Subjects: Cryptography and Security (cs.CR) MSC classes: 94A60, 68M10, 68P25 ACM classes: C.2.2; E.3; K.6.5 Cite as: arXiv:2604.06100 [cs.CR]   (or arXiv:2604.06100v1 [cs.CR] for this version)   https://doi.org/10.48550/arXiv.2604.06100 Focus to learn more Submission history From: José Luis Delgado [view email] [v1] Tue, 7 Apr 2026 17:13:10 UTC (138 KB) Access Paper: HTML (experimental) 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?)