{
  "abstract": "Existing side-channel theories treat leakage as a holistic quantity $I(X;Y)$, without characterizing its internal structure. This paper studies the \\emph{structural decomposability} of encrypted-traffic side-channel leakage. Via the structural causal model $X\\!\\to\\!Y_{\\mathrm{size}}\\!\\to\\!Y_{\\mathrm{dir}}\\!\\to\\!Y_{\\mathrm{time}}$ and the mutual-information chain rule, total leakage is decomposed into three sequential increments for packet size, direction, and timing. Defenses are formalized as mechanism replacement by a strategy variable~$D$; coupling information $C_{\\mathrm{size,dir}}=I(Y_{\\mathrm{size}};Y_{\\mathrm{dir}}\\!\\mid\\!X)$ measures inter-dimensional dependence, and the Markov residual gives a testable condition for a single-dimension defense to sever downstream leakage. Causal efficacy~$η_d$ quantifies per-unit-cost suppression, and a Fisher-geometric approximation $I(X;Y)\\approx\\frac{1}{2\\ln 2}\\mathrm{Tr}(GΣ_θ)$ holds under small perturbations. On the Wang dataset (95 websites), $Y_{\\mathrm{dir}}$ dominates undefended leakage (0.637\\,bits), while Tor's fixed 512-byte cells make $Y_{\\mathrm{size}}$ degenerate; FRONT suppresses the direction term by 63\\%, yet its Markov residual of 0.021\\,bits (95\\% CI $[0.016,0.027]$) shows it cannot sever timing leakage; $η_{\\mathrm{dir}}=0.97$ vs. $η_{\\mathrm{time}}\\approx 0$ confirms FRONT's design intent. This yields a computable, structured leakage-accounting method for multi-dimensional joint defense design.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.19036",
  "author_total": 3,
  "authors": [
    {
      "name": "Guangjie Liu"
    },
    {
      "name": "Guang Cheng"
    },
    {
      "name": "Weiwei Liu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/0fwcn721xe541.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.19036",
  "fulltext_url": null,
  "id": "0fwcn721xe541",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.19036",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cs.CR"
    ],
    [
      "arxiv",
      "cs.IT"
    ],
    [
      "arxiv",
      "math.IT"
    ],
    [
      "openalex",
      "1702|Internet Traffic Analysis and Secure E-voting"
    ]
  ],
  "openalex": "W7213506714",
  "pdf_url": "https://arxiv.org/pdf/2609.19036",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/0fwcn721xe541.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:04Z",
      "native_id": "2609.19036",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.19036"
    }
  ],
  "subjects": [
    {
      "field": "mathematics",
      "origin": "arxiv:math.IT",
      "subfield": "general"
    }
  ],
  "title": "Structural Decomposability of Encrypted Traffic Side-Channel Leakage",
  "title_text": "Structural Decomposability of Encrypted Traffic Side-Channel Leakage",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:04Z",
  "url": "https://research.draconitic.com/paper/0fwcn721xe541",
  "venue": "arXiv",
  "versions": []
}