{
  "abstract": "With the rapid advancement of quantum computing, the security of traditional cryptographic systems is facing significant challenges. As a fundamental component of symmetric cryptography, block ciphers have attracted increasing attention regarding their quantum security in recent years. In this paper, we propose new quantum attacks on two Feistel-type constructions, i.e., New Structure IV and the lightweight block cipher LBlock, under the quantum chosen-plaintext attack (qCPA) model. First, we construct an 8-round quantum distinguisher for New Structure IV and perform an $r(r>12)$-round quantum key-recovery attack. Compared with Li et al.'s qCPA-based result presented at INSCRYPT 2024, our attack reduces the time complexity by a factor of $2^{n/2}$, where $n$ denotes the subkey length. Second, we design a 9-round quantum distinguisher for LBlock and extend it to an $r(r>15)$-round quantum key-recovery attack. The proposed quantum distinguisher covers one more round than Liu et al.'s automated-search distinguisher at ASIACRYPT 2025, which results in a $2^{16}$ reduction in the time complexity of our $r$-round quantum key-recovery attack on LBlock. Furthermore, by analyzing the structure of the round function and the key scheduling of LBlock, we reduce the subkey guess space for the 15-round attack from 76 bits to 52 bits, lowering the time complexity from \\(O(2^{38})\\) to \\(O(2^{26})\\) by a factor of \\(2^{12}\\).",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.27506",
  "author_total": 4,
  "authors": [
    {
      "name": "Yan-Ying Zhu"
    },
    {
      "name": "Bin-Bin Cai"
    },
    {
      "name": "Fei Gao"
    },
    {
      "name": "Song Lin"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/736w2bnkz2wn3.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.27506",
  "fulltext_url": null,
  "id": "736w2bnkz2wn3",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.27506",
  "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",
      "quant-ph"
    ],
    [
      "openalex",
      "1702|Cryptographic Implementations and Security"
    ]
  ],
  "openalex": "W7223144914",
  "pdf_url": "https://arxiv.org/pdf/2610.27506",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-20",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/736w2bnkz2wn3.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:04Z",
      "native_id": "2610.27506",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.27506"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Quantum Cryptanalysis on Two Feistel-Type Constructions",
  "title_text": "Quantum Cryptanalysis on Two Feistel-Type Constructions",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:04Z",
  "url": "https://research.draconitic.com/paper/736w2bnkz2wn3",
  "venue": "arXiv",
  "versions": []
}