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    "story_id": "mp-2026-10-01-015",
    "source_story_id": "tmp-sidebar-quantum-secure-two-round-cipher",
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    "headline": "Two Rounds Were the Minimum for This Quantum-Secure Cipher",
    "slug": "two-rounds-were-the-minimum-for-this-quantum-secure-cipher",
    "dek": "The Even-Mansour construction survived adaptive forward and inverse quantum queries in the ideal-permutation model.",
    "summary": "The Even-Mansour construction survived adaptive forward and inverse quantum queries in the ideal-permutation model.",
    "body_text": "The authors prove information-theoretic security for the two-round Even-Mansour cipher against polynomially many adaptive quantum queries to all available oracles. They also show that essentially any construction with only one public-permutation call is quantumly insecure, making two rounds minimal within the stated model.",
    "why_it_matters": "The Even-Mansour construction survived adaptive forward and inverse quantum queries in the ideal-permutation model.",
    "limitations": [
      "They also show that essentially any construction with only one public-permutation call is quantumly insecure, making two rounds minimal within the stated model."
    ],
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    "first_published_at": "2026-10-01T09:00:00.000-04:00",
    "modified_at": "2026-10-01T09:00:00.000-04:00",
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        "text": "The Even-Mansour construction survived adaptive forward and inverse quantum queries in the ideal-permutation model.",
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        "qualification": "They also show that essentially any construction with only one public-permutation call is quantumly insecure, making two rounds minimal within the stated model."
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    "source_ids": [
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    "tags": [
      "post-quantum cryptography",
      "block ciphers",
      "quantum queries"
    ],
    "image_url": null,
    "corrections": []
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  "sources": [
    {
      "source_id": "source-2026-10-01-017",
      "title": "arXiv preprint 2609.40350",
      "publisher": "arXiv",
      "url": "https://arxiv.org/abs/2609.40350",
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      "published_at": "2026-09-30T13:59:10.000-04:00",
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  "publisher": {
    "name": "The Machine Press",
    "url": "https://themachinepress.com",
    "description": "A daily newspaper for the age of artificial intelligence."
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    "title": "Two Rounds Were the Minimum for This Quantum-Secure Cipher",
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