一般化Feistel型ブロック暗号における差分特性確率のtruncatedパス探索について

カテゴリ: 部門大会

論文No: GS20-5

グループ名: 【C】平成22年電気学会電子・情報・システム部門大会講演論文集

発行日: 2010/09/02

タイトル(英語): On the truncated path search for differential characteristic probability on a generalized Feistel-type block cipher

著者名: 五十嵐 保隆(東京理科大学),金子 敏信(東京理科大学)

著者名(英語): Igarashi Yasutaka(Tokyo University of Science),Toshinobu Kaneko(Tokyo University of Science)

キーワード: 暗号|ビタビアルゴリズム|差分確率|トランケーション|Feistel|cryptography|Viterbi algorithm|differential probability|truncation|Feistel

要約(日本語): We study a Viterbi search for differential characteristic probability (DCP) of a block cipher with a generalized Feistel
structure, referred to as a generalized Feistel-type cipher (GFC). DCP is a security index of differential cryptanalysis. The upper bound of DCP is given by a truncated-path search with Viterbi algorithm. We show that the truncated-path search gives an imaginary path as the resultant optimum path in GFC, which cannot be connected as a real path. We also propose a new search algorithm to avoid such imaginary paths. Our algorithm can give the upper bound of DCP tighter than conventional one.

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