機械学習への応用を目指した安全かつ高効率な高機能暗号の研究

• Project/Area Number: 17J05603
• Research Category: Grant-in-Aid for JSPS Fellows
• Allocation Type: Single-year Grants
• Section: 国内
• Research Field: Information security
• Research Institution: The University of Tokyo
• Principal Investigator: 勝又 秀一 東京大学, 新領域創成科学研究科, 特別研究員(DC2)
• Project Period (FY): 2017-04-26 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥1,900,000 (Direct Cost: ¥1,900,000); Fiscal Year 2018: ¥900,000 (Direct Cost: ¥900,000); Fiscal Year 2017: ¥1,000,000 (Direct Cost: ¥1,000,000)
• Keywords: 高機能暗号 / 機械学習 / プライバシーリスク

Outline of Annual Research Achievements

本研究の目的は，機械学習アルゴリズムに潜在するプライバシーリスクの解明，および，機械学習への応用が期待される高機能暗号方式の十分に安全でかつ効率的な構成である．本年度の成果は，六本の査読付き国際会議と一本の論文誌採録である．以下，特筆すべき二件の成果を説明する．
一つ目は，高効率な耐量子性を備えたIDベース暗号の提案である．IDベース暗号とは，高機能暗号の中で最もシンプルかつ基礎的で，より高機能な暗号方式への出発地点となるため，活発に研究が行われている．また，近年は量子計算機の台頭を危惧し，量子計算機をもってしても安全性が破られない耐量子性を備えた暗号方式が注目を浴びている．本研究で提案するIDベース暗号は，STOC'08にGentry-Peikert-Vaikuntanathanが提案した格子に基づく現在もっとも効率的な耐量子IDベース暗号をベースにしており，量子ランダムオラクルモデルにおいて新しい証明を与えたことが最大の貢献である．本成果は，暗号理論分野の三大国際会議の一つであるASIACRYPTに採録された．
二つ目は，ゼロ知識証明を活用しない，初めての耐量子性を備えたグループ署名の提案である．グループ署名とは，自身の匿名性を守りながらグループに参加しているユーザを代表して署名を打てる高機能な署名方式である．それに加え，特別な管理者は署名を非匿化することができるため，不正検知機構も備わっている．従来，グループ署名はゼロ知識証明を経由する構成方法しか知られていなかったが，ゼロ知識証明は耐量子性を持つ数学的道具からの構成方法が知られていなかった．本研究では，ゼロ知識証明を経由しない新しい証明手法を提案し，初めての耐量子性を備えたグループ署名を提案したことが最大の貢献である．本成果は，暗号理論分野の三大国際会議の一つであるEUROCRYPTに採録された．

Research Progress Status

平成30年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

平成30年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] University of Oxford(英国)
• [Int'l Joint Research] University of Oxford(英国)
• [Journal Article] Non-Zero Inner Product Encryption Schemes from Various Assumptions: LWE, DDH and DCR (2019)
  • Author(s): Shuichi Katsumata, Shota Yamada
  • Journal Title: Public Key Cryptography (PKC), Lecture Notes in Computer Science Volume: 11443
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Lattice-based Revocable (Hierarchical) IBE with Decryption Key Exposure Resistance (2019)
  • Author(s): Shuichi Katsumata, Takahiro Matsuda, Atsushi Takayasu
  • Journal Title: Public Key Cryptography (PKC), Lecture Notes in Computer Science Volume: 11443
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Group Signatures Without NIZK: From Lattices in the Standard Model (2019)
  • Author(s): Shuichi Katsumata, Shota Yamada
  • Journal Title: EUROCRYPT, Lecture Notes in Computer Science Volume: 11478
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Designated Verifier/Prover and Preprocessing NIZKs from Diffie-Hellman Assumptions (2019)
  • Author(s): Shuichi Katsumata, Nishimaki Ryo, Shota Yamada, Takashi Yamakawa
  • Journal Title: EUROCRYPT, Lecture Notes in Computer Science Volume: 11477
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Model Inversion Attacks for Online Prediction Systems: Without Knowledge of Non-Sensitive Attributes (2018)
  • Author(s): Hidano Seira、Murakami Takao、Katsumata Shuichi、Kiyomoto Shinsaku、Hanaoka Goichiro
  • Journal Title: IEICE Transactions on Information and Systems Volume: E101.D Issue: 11 Pages: 2665-2676
  • DOI: 10.1587/transinf.2017ICP0013
  • ISSN: 0916-8532, 1745-1361
  • Year and Date: 2018-11-01
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Tighter Security Proofs for GPV-IBE in the Quantum Random Oracle Model. (2018)
  • Author(s): Shuichi Katsumata, Takashi Yamakawa, Shota Yamada
  • Journal Title: Advances in Cryptology - ASIACRYPT 2018 Volume: 11273 Pages: 252-282
  • DOI: 10.1007/978-3-030-03329-3_9
  • ISBN: 9783030033286, 9783030033293
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Attribute-Based Signatures for Unbounded Languages from Standard Assumptions (2018)
  • Author(s): Sakai Yusuke、Katsumata Shuichi、Attrapadung Nuttapong、Hanaoka Goichiro
  • Journal Title: ASIACRYPT, Lecture Notes in Computer Science Volume: 11273 Pages: 493-522
  • DOI: 10.1007/978-3-030-03329-3_17
  • ISBN: 9783030033286, 9783030033293
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Attribute-Based Signatures for Unbounded Circuits in the ROM and Efficient Instantiations from Lattices (2018)
  • Author(s): Ali El Kaafarani and Shuichi Katsumata
  • Journal Title: Public Key Cryptography (PKC), Lecture Notes in Computer Science Volume: 10770 Pages: 89-119
  • DOI: 10.1007/978-3-319-76581-5_4
  • ISBN: 9783319765808, 9783319765815
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Constructing Subspace Membership Encryption through Inner Product Encryption (2017)
  • Author(s): Shuichi Katsumata and Noboru Kunihiro
  • Journal Title: IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences Volume: E100.A Issue: 9 Pages: 1804-1815
  • DOI: 10.1587/transfun.E100.A.1804
  • NAID: 130006038283
  • ISSN: 0916-8508, 1745-1337
  • Peer Reviewed
• [Journal Article] On the Untapped Potential of Encoding Predicates by Arithmetic Circuits and Their Applications (2017)
  • Author(s): Shuichi Katsumata
  • Journal Title: ASIACRYPT, Lecture Notes in Computer Science Volume: 10626 Pages: 95-125
  • DOI: 10.1007/978-3-319-70700-6_4
  • ISBN: 9783319706993, 9783319707006
  • Peer Reviewed / Open Access
• [Presentation] Tighter Security Proofs for GPV-IBE in the Quantum Random Oracle Model (2018)
  • Author(s): Katsumata Shuichi、Yamada Shota、Yamakawa Takashi
  • Organizer: 24th International Conference on the Theory and Applications of Cryptology and Information Security ASIACRYPT 2018
  • Int'l Joint Research
• [Presentation] Attribute-Based Signatures for Unbounded Languages from Standard Assumptions (2018)
  • Author(s): Sakai Yusuke、Katsumata Shuichi、Attrapadung Nuttapong、Hanaoka Goichiro
  • Organizer: 24th International Conference on the Theory and Applications of Cryptology and Information Security ASIACRYPT 2018
  • Int'l Joint Research
• [Presentation] 鍵生成センタに対して安全なIDべース暗号 (2018)
  • Author(s): 江村恵太、勝又秀一、渡邉洋平
  • Organizer: 2019年暗号と情報セキュリティシンポジウム (SCIS2019)、滋賀
• [Presentation] 準同型署名の弱安全性から強安全性への効率的な変換 (2018)
  • Author(s): 伊藤宗一郎、勝又秀一、國廣昇
  • Organizer: 2019年暗号と情報セキュリティシンポジウム (SCIS2019)、滋賀
• [Presentation] Attribute-based Signatures for Unbounded Circuits in the ROM and Efficient Instantiations from Lattices (2018)
  • Author(s): Ali El Kaafarani and Shuichi Katsumata
  • Organizer: 21st International Conference on Practice and Theory of Public-Key Cryptography (PKC) 2018
  • Int'l Joint Research
• [Presentation] Anonymous Reputation Systems Achieving Full Dynamicity from Lattices (2018)
  • Author(s): Ali El Kaafarani, Shuichi Katsumata and Ravital Solomon
  • Organizer: 21st International Conference of Financial Cryptography and Data Security (FC) 2018
  • Int'l Joint Research
• [Presentation] On the Untapped Potential of Encoding Predicates by Arithmetic Circuits and Their Applications (2017)
  • Author(s): Shuichi Katsumata
  • Organizer: 23rd International Conference on the Theory and Applications of Cryptology and Information Security ASIACRYPT 2017
  • Int'l Joint Research
• [Presentation] Model Inversion Attacks for Prediction Systems: Without Knowledge of Non-Sensitive Attributes (2017)
  • Author(s): Seira Hidano, Takao Murakami, Shuichi Katsumata, Shinsaku Kiyomoto and Goichiro Hanaoka
  • Organizer: Privacy, Security and Trust (PST)
  • Int'l Joint Research
• [Presentation] 述語の効率的な回路への埋込によるコンパクトな検証可能擬似乱数可能関数 (2017)
  • Author(s): 勝又秀一
  • Organizer: 2017年コンピュータセキュリティシンポジウム(CSS2017)，山形
• [Presentation] 協調フィルタリングに対するModel Inversion1攻撃の提案 (2017)
  • Author(s): 披田野清良，村上隆夫，勝又秀一，清本晋作，花岡悟一郎
  • Organizer: 2017年コンピュータセキュリティシンポジウム(CSS2017)，山形
• [Presentation] 復号鍵漏洩耐性を持つ鍵失効機能付きIDベース暗号の一般的な構成 (2017)
  • Author(s): 高安敦，勝又秀一，松田隆宏
  • Organizer: 2017年コンピュータセキュリティシンポジウム(CSS2017)，山形
• [Presentation] 標準的仮定に基づくMulti-key IDベース完全準同型暗号の構成 (2017)
  • Author(s): 近藤佑樹，勝又秀一，國廣昇
  • Organizer: 2018年暗号と情報セキュリティシンポジウム (SCIS2018)，秋田