{
  "abstract": "Networking defenses against traffic analysis fill idle slots with cover traffic, yet the physical layer carrying it still hands upper layers the erasure-only model of a silent-idle link, leaving the cover content unexploited. We shape that content: the idle-slot waveform is drawn from the codebook complement under a design distribution, the \\emph{litter distribution}, chosen to defeat a public-design passive observer while the upper layer keeps its block z-channel model. The maximum a posteriori (MAP) receiver reduces to a single threshold on the log-likelihood ratio between the best codeword and the prior-weighted litter aggregate; its errors are silent corruptions the upper layer cannot detect and erasures that retransmission absorbs. Receiver design is thus one-dimensional, minimizing erasure under a cap on silent corruption, and the joint design a Stackelberg game against a Kullback-Leibler (KL) indistinguishability metric, solved by an alternating convex relaxation and corroborated by an independent reinforcement-learning policy. On a rate-$3/4$ $(16,12)$ parity-check (LDPC) code against an observer who knows her own channel but whose channel the transmitter knows only statistically, shaped litter cuts the observer's Stein detection exponent by $41$ to $48\\%$ relative to uniform cover, flat over a $10$~dB span and in the activity rate. Below the point where the legitimate link turns reliable, no cover distribution admits an operating point; at that point shaping costs about one percent of throughput, and nothing measurable $2$~dB above it.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.31767",
  "author_total": 6,
  "authors": [
    {
      "name": "Bin Han"
    },
    {
      "name": "Wenwen Chen"
    },
    {
      "name": "Yao Zhu"
    },
    {
      "name": "Rafael F. Schaefer"
    },
    {
      "name": "Giuseppe Caire"
    },
    {
      "name": "Hans D. Schotten"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/crecy834qxa48.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.31767",
  "fulltext_url": null,
  "id": "crecy834qxa48",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.31767",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cs.IT"
    ],
    [
      "arxiv",
      "eess.SP"
    ],
    [
      "arxiv",
      "math.IT"
    ],
    [
      "openalex",
      "2208|Wireless Communication Security Techniques"
    ]
  ],
  "openalex": "W7214764665",
  "pdf_url": "https://arxiv.org/pdf/2609.31767",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-24",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/crecy834qxa48.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:17Z",
      "native_id": "2609.31767",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.31767"
    }
  ],
  "subjects": [
    {
      "field": "mathematics",
      "origin": "arxiv:math.IT",
      "subfield": "general"
    }
  ],
  "title": "Litter-Masked Block z-Channel: Designing Cover Distributions Against Public-Design Observers",
  "title_text": "Litter-Masked Block z-Channel: Designing Cover Distributions Against Public-Design Observers",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:17Z",
  "url": "https://research.draconitic.com/paper/crecy834qxa48",
  "venue": "arXiv",
  "versions": []
}