Mitsugu Iwamoto
| Department of Informatics | Professor |
| Cluster II (Emerging Multi-interdisciplinary Engineering) | Professor |
- Profile:
2001-present: Information Security, Cryptography, Information theory
1999-2001: High-performance computing
Researcher Information
Degree
Research Keyword
Field Of Study
Career
- 01 Apr. 2021
Graduate School of Information and Engineering, The University of Electro-Communications, Department of Informatics, Professor - 01 Apr. 2016 - 31 Mar. 2021
Graduate School of Information and Engineering, The University of Electro-Communications, Department of Informatics, Associate Professor - 01 Apr. 2015 - 31 Mar. 2016
Graduate School of Information and Engineering, The University of Electro-Communications, Department of Informatics, Associate Professor - 01 Dec. 2012 - 31 Mar. 2015
Cernter for Frontier Science and Engineering, The University of Electro-Communications, Tenure Track Associate Professor - 01 Jun. 2010 - 30 Nov. 2012
Cernter for Frontier Science and Engineering, The University of Electro-Communications, Tenure Track Assistant Professor - 01 Apr. 2007 - 31 May 2010
Graduate School of Information Systems, the University of Electro-Communications, Department of Information Network System, Assistant Professor - 01 Apr. 2004 - 31 Mar. 2007
Graduate School of Information Sysytems, University of Electro-communications, Department of Information System Science, Research Associate
Educational Background
- Mar. 2004
The University of Tokyo, Graduate School of Infoemarion Science and Technology, Department of Mathematical Informatics - Mar. 2001
The University of Tokyo, Graduate School, Division of Engineering, 計数工学 - Mar. 1999
The University of Tokyo, Faculty of Engineering, Mathmatical Engineering and Information Physics - 01 Apr. 1992 - 31 Mar. 1995
Sugamo High School, Japan
Member History
- Mar. 2025 - Apr. 2026
編集委員, 2026年 電子情報通信学会論文誌 情報理論とその応用小特集 編集委員会, Society - Apr. 2025 - Mar. 2026
編集委員, 2026年 電子情報通信学会論文誌 暗号と情報セキュリティ小特集 編集委員会, Society - Apr. 2024 - Mar. 2025
編集委員, 2025年 電子情報通信学会論文誌 情報理論とその応用小特集 編集委員会, Society - Apr. 2024 - Mar. 2025
編集委員, 2025年 電子情報通信学会論文誌 暗号と情報セキュリティ小特集 編集委員会, Society - Jan. 2024 - Sep. 2024
Program Committee Member, 2024 IWSEC (International Workshop on Security), Society - Jun. 2023 - May 2024
Editor-in-Chief, IEICE Trans. Fundamentals, Society - Jun. 2022 - May 2024
Editor-in-Chief, IEICE Trans. Fundamentals (Japanese Edition), Society - Apr. 2023 - Mar. 2024
編集委員, 2024年 電子情報通信学会論文誌暗号と情報セキュリティ小特集号編集委員, Society - Aug. 2023
Program Committee Member, IWSEC2023, Society - Jun. 2017 - May 2023
専門委員, 電子情報通信学会 情報理論研究専門委員会, Society - Apr. 2022 - Mar. 2023
編集委員, 2023年 電子情報通信学会論文誌暗号と情報セキュリティ小特集号, Society - Apr. 2022 - Mar. 2023
暗号技術調査ワーキンググループ（高機能暗号）委員, CRYPTREC, Government, 暗号に関するガイドラインの策定，執筆 - Jan. 2022 - Dec. 2022
実行委員（アドバイザ）, 情報理論とその応用シンポジウム (SITA2022), Society - Aug. 2019 - Oct. 2021
Program co-chair, IEEE Information Theory Workshop, IEEE Information Theory Society, Society - 05 Jun. 2014 - 03 Jun. 2020
専門委員, 電子情報通信学会 情報セキュリティ研究会 - 02 Jun. 2016 - 31 May 2017
幹事補佐, 電子情報通信学会 情報理論研究会 - 05 Jun. 2014 - 01 Jun. 2016
幹事, 電子情報通信学会 情報理論研究専門委員会 - 25 May 2013 - 03 Jun. 2015
電子広報担当幹事, 電子情報通信学会 基礎・境界ソサイエティ 運営委員会, Society - 25 May 2007 - 24 May 2013
専門委員, 電子情報通信学会 情報理論研究会研究専門委員会, Society - May 2010 - Apr. 2013
委員（広報担当）, 電子情報通信学会 情報理論とその応用サブソサイエティ運営委員会, Society - Apr. 2009 - Mar. 2011
編集幹事, 情報理論とその応用学会, Society - Apr. 2007 - Mar. 2009
WEB担当幹事, 情報理論とその応用学会, Society
Research Activity Information
Award
- Oct. 2024
検索可能暗号に対するより効果的なクエリ復元攻撃
CSS奨励賞, 並木拓海;岩本貢;渡邉洋平 - Oct. 2024
コンピュータセキュリティシンポジウム
TFHEを用いた高速な否認可能完全準同型暗号
CSS奨励賞, 豊岡叶望;渡邉洋平;岩本貢 - Jan. 2023
電子情報通信学会 情報セキュリティ研究会
（指導学生の受賞）
SCIS論文賞, 安部芳紀 - Oct. 2022
情報誌処理学会, CSS2022全論文（２００件以上）の中から５編以内．最優秀論文賞（２編）に次ぐ賞． https://www.iwsec.org/css/2022/award.html#css
カードを用いた秘匿和集合プロトコル
CSS優秀論文賞, 土井 アナスタシヤ;小野 知樹;安部 芳紀;産業技術総;渡邉 洋平;産業技術総;岩本 貢
Japan society, Japan - Jan. 2021
IEICE情報セキュリティ研究会
（指導学生の受賞）
SCIS論文賞, 中井雄士
Japan society - Oct. 2020
コンピュータセキュリティシンポジウム
より少ない漏洩の下で安全な動的検索可能暗号への変換手法
CSS2020 奨励賞, 渡邉洋平;大原一真;岩本貢;太田和夫
Japan society, Japan - Sep. 2020
IEICE, IEICE和文論文誌の幹事と２年勤めたため
Japan
電子情報通信学会貢献賞
Others, Japan - Jun. 2020
電子情報通信学会ISEC研究専門委員会
長年にわたる専門委員としての研究会運営に対する協力
ISEC研究活動貢献感謝状, 岩本貢
Official journal - Jan. 2020
電子情報通信学会情報セキュリティ研究会 (ISEC)
（指導学生の受賞）初期文字列が29文字の4入力多数決Private PEZプロトコル
情報セキュリティ研究奨励賞, 安部芳紀;太田;岩本;渡邉研究室
Japan society - Oct. 2019
このピュータセキュリティシンポジウム
(強)フォワード安全な動的検索可能暗号の効率的な構成
CSS2019 奨励賞, 渡邉洋平;大原一真;岩本貢;太田和夫
Japan society, Japan - Sep. 2019
IEICE, 電子情報通信学会論文誌・情報理論とその応用小特集号．幹事としての貢献
Japan
電子情報通信学会貢献賞
Official journal, Japan - Aug. 2019
International Workshop on Information Security (IWSEC)
IWSEC best poster award, Yoshiki Abe;Mitsugu Iwamoto;Kazuo Ohta
International society - Sep. 2018
IEICE, IEICE和文・英文論文誌の編集委員を２期４年勤めたため
Japan
電子情報通信学会貢献賞
Others, Japan - Mar. 2018
サイバーセキュリティシンポジウム道後
サイバーセキュリティシンポジウム道後2018学生研究賞, 庄司奈津;菅原健;岩本貢;崎山一男
Japan society - Sep. 2017
IEICE, 基礎・境界ソサイエティ，情報理論研究会の幹事および幹事補佐を計３年務めたため
Japan
電子情報通信学会貢献賞
Others, Japan - Feb. 2017
サイバーセキュリティシンポジウム道後
サイバーセキュリティシンポジウム道後2017学生研究賞, 八代理紗;町田卓謙;岩本貢;崎山一男
Japan society - Sep. 2015
IEICE, 基礎・境界ソサイエティの電子広報担当幹事を２年務めたため
Japan
電子情報通信学会貢献賞
Others, Japan - Sep. 2014
IEICE, 査読委員として，査読本数が多いことによる
Japan
電子情報通信学会感謝状
Others, Japan - Sep. 2012
IEICE, 査読委員として，査読本数が多いことによる
Japan
電子情報通信学会感謝状
Others, Japan - Nov. 2005
情報理論とその応用学会
SITA奨励賞, 岩本貢
Paper
- Dynamic Collateral Management in Decentralized Sealed-Bid Auctions
Kholiq Abdullah; Mitsugu Iwamoto; Yohei Watanabe
ICIMCIS 2024, to appear, Nov. 2024, Peer-reviwed
International conference proceedings, English - On the Attack Detection Performance of Information-theoretic Method in Industrial Control System
T. Nishiuchi; Y. Abe; Y. Watanabe; M. Iwamoto; K. Sawada; S. Shin
IECON 2024, to appear, Nov. 2024, Peer-reviwed
International conference proceedings, English - 時間ドロボー問題に対する健全性誤りのない物理的ゼロ知識証明
初貝 恭祐; 安部 芳紀; 中井 雄士; 品川 和雅; 渡邉; 洋平; 岩本 貢
Last, 電子情報通信学会論文誌 A, to appear, Nov. 2024, Peer-reviwed
Scientific journal, Japanese - Double-Sided Multimodal Attack Sensing and Partial Re-Keying in Shared Group Key System
R. Ikemoto; S. Fujii; K. Naruse; J. Shiomiand; Y. Midoh; Y. Yamashita; M. Taguchi; T. Miki; M. Nagata; Y. Komano; M. Iwamoto; K. Sakiyama; N. Miura
ESSERC2024, to appear, Sep. 2024, Peer-reviwed
International conference proceedings, English - Card-based Cryptography with a Standard Deck of Cards, Revisited: Efficient Protocols in the Private Model.
Takeshi Nakai; Keita Iwanari; Tomoki Ono; Yoshiki Abe; Yohei Watanabe 0001; Mitsugu Iwamoto
Last, New Gener. Comput., Springer Science and Business Media LLC, 42, 3, 345-358, Sep. 2024, Peer-reviwed, Abstract
Card-based cryptography is a secure computation protocol realized by using physical cards. There are two models on card-based cryptography: public and private models. We adopt private one that allows players to handle cards privately. While much of the existing works for card-based cryptography use two-colored cards, it is also a vital task to construct an efficient protocol with playing cards. In the public model, 2n cards are necessary for any n-bit input protocol since at least two cards are required to express a Boolean value. It holds true for both two-colored and playing-card settings. On the other hand, the private model enables us to construct a protocol with fewer than 2n cards. However, all existing protocols that achieve such properties are only in the two-colored setting. This paper shows that the private model enables us to construct a protocol with fewer than 2n cards using the playing cards. We first show two-bit input protocols with fewer than four cards for logical operations, AND, OR, and XOR. Furthermore, we show a three-input majority voting protocol using only three cards, which is constructed by combining our AND and OR protocols. Notably, our proposed protocols require no randomness. All operations are deterministic and depend only on players’ private inputs.
Scientific journal - Multi-User Dynamic Searchable Encryption for Prefix-Fixing Predicates from Symmetric-Key Primitives
T. Hirano; Y. Kawai; Y. Koseki; S. Yasuda; Y. Watanabe; T. Amada; M. Iwamoto; K. Ohta
SAC2024, to appear, Aug. 2024, Peer-reviwed
International conference proceedings, English - 高機能暗号の社会展開を促進する物理・視覚暗号
花岡悟一郎; 岩本貢; 渡邉洋平; 水木敬明; 安部芳紀; 品川和雅; 新井美音; 矢内直人
電子情報通信学会和文論文誌A, J106, A, Aug. 2023, Peer-reviwed, Invited
Scientific journal, Japanese - A Computationally Efficient Card-Based Majority Voting Protocol with Fewer Cards in the Private Model.
Yoshiki Abe; Takeshi Nakai; Yohei Watanabe 0001; Mitsugu Iwamoto; Kazuo Ohta
Last, IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Institute of Electronics, Information and Communications Engineers (IEICE), 106, 3, 315-324, Mar. 2023, Peer-reviwed
Scientific journal - Secure Computation for Threshold Functions with Physical Cards: Power of Private Permutations.
Takeshi Nakai; Satoshi Shirouchi; Yuuki Tokushige; Mitsugu Iwamoto; Kazuo Ohta
Last, New Generation Computing, Springer Science and Business Media LLC, 40, 1, 95-113, 08 Feb. 2022, Peer-reviwed, Abstract
Card-based cryptography is a variant of multi-party computation using physical cards like playing cards. There are two models on card-based cryptography, called public and private models. The public model assumes that all operations are executed publicly, while the private model allows the players private operations called private permutations (PP, for short). Much of the existing card-based protocols were developed under the public model. Under the public model, 2n cards are necessary for every protocol with n-bit input since at least two cards are required to express a bit. In this paper, we propose n-bit input protocols with fewer than 2n cards by utilizing PP, which shows the power of PP. In particular, we show that a protocol for (n-bit input) threshold function can be realized with only $$n+1$$ cards by reducing the threshold function to the majority voting. Toward this end, we first offer that two-bit input protocols for logic gates can be realized with fewer than four cards. Furthermore, we construct a new protocol for three-input majority voting with only four cards by observing the relationship between AND/OR operations. This protocol can be easily extended to more participants, and to the protocol for threshold functions.
Scientific journal - Lightweight Authentication Using Noisy Key Derived from Physically Unclonable Function.
Yuichi Komano; Mitsugu Iwamoto; Kazuo Ohta; Kazuo Sakiyama
Innovative Security Solutions for Information Technology and Communications - 15th International Conference(SecITC), Springer, 203-221, 2022, Peer-reviwed
International conference proceedings - Efficient Dynamic Searchable Encryption with Forward Privacy under the Decent Leakage.
Yohei Watanabe 0001; Kazuma Ohara; Mitsugu Iwamoto; Kazuo Ohta
CODASPY '22: Twelveth ACM Conference on Data and Application Security and Privacy(CODASPY), ACM, -, -, 312-323, 24 Apr. 2022, Peer-reviwed
International conference proceedings, English - Efficient Card-Based Majority Voting Protocols.
Yoshiki Abe; Takeshi Nakai; Yoshihisa Kuroki; Shinnosuke Suzuki; Yuta Koga; Yohei Watanabe 0001; Mitsugu Iwamoto; Kazuo Ohta
Last, New Generation Computing, Springer Science and Business Media LLC, 40, 1, 173-198, 23 Mar. 2022, Peer-reviwed, Abstract
Card-based cryptography is a variety of secure multiparty computation (MPC). Recently, a new technique called private operations was introduced because the protocol can be implemented with fewer cards than that by using the conventional technique called the shuffle. For example, Nakai et al. showed that if the private operations are available, secure computations of AND and OR operations for two inputs can be realized simultaneously by using four cards, and the protocol is applied to a four-card majority voting protocol with three inputs. This paper shows that only three cards are sufficient to construct a majority voting protocol with three inputs. Specifically, we propose two constructions of three-input majority voting protocols. One is a protocol assuming that players can announce their output, and the other is not allowed. Compared to Nakai et al.’s protocol, the protocol with the announcement is realized without any additional private operations and communications. On the other hand, the second construction requires two more private operations and communications because it removes the assumption on the announcement from the first construction. More importantly, the idea of the second protocol can be extended to an n-input majority voting protocol with n cards, which is the main result of this paper.
Scientific journal - How to Make a Secure Index for Searchable Symmetric Encryption, Revisited.
Yohei Watanabe 0001; Takeshi Nakai; Kazuma Ohara; Takuya Nojima; Yexuan Liu; Mitsugu Iwamoto; Kazuo Ohta
IACR Cryptology ePrint Archive, Institute of Electronics, Information and Communications Engineers (IEICE), 2021, 12, 948-948, 2021, Peer-reviwed
Scientific journal - A Key Recovery Algorithm Using Random Key Leakage from AES Key Schedule.
Tomoki Uemura; Yohei Watanabe 0001; Yang Li 0001; Noriyuki Miura; Mitsugu Iwamoto; Kazuo Sakiyama; Kazuo Ohta
Last, International Symposium on Information Theory and Its Applications(ISITA), IEEE, -, -, 382-386, 24 Oct. 2020, Peer-reviwed
International conference proceedings, English - An IC-level countermeasure against laser fault injection attack by information leakage sensing based on laser-induced opto-electric bulk current density
Kohei Matsuda; Sho Tada; Makoto Nagata; Yuichi Komano; Yang Li; Takeshi Sugawara; Mitsugu Iwamoto; Kazuo Ohta; Kazuo Sakiyama; Noriyuki Miura
Japanese Journal of Applied Physics, IOP Publishing, 59, SG, SGGL02-SGGL02, 01 Apr. 2020, Peer-reviwed, Abstract
Laser fault injection (LFI) attacks on cryptographic processor ICs are a critical threat to information systems. This paper proposes an IC-level integrated countermeasure employing an information leakage sensor against an LFI attack. Distributed bulk current sensors monitor abnormal bulk current density caused by laser irradiation for LFI. Time-interleaved sensor operation and sensitivity tuning can obtain partial secret key leakage bit information with small layout area penalty. Based on the leakage information, the secret key can be securely updated to realize high-availability resilient systems. The test chip was designed and fabricated in a 0.18 μm standard CMOS, integrating a 128-bit advanced encryption standard cryptographic processor with the proposed information leakage sensor. This evaluation successfully demonstrated bulk current density and leakage bit monitoring.
Scientific journal - How to Detect Malicious Behaviors in a Card-Based Majority Voting Protocol with Three Inputs.
Yoshiki Abe; Mitsugu Iwamoto; Kazuo Ohta
International Symposium on Information Theory and Its Applications(ISITA), IEEE, -, -, 377-381, 24 Oct. 2020, Peer-reviwed
International conference proceedings, English - Multi-Party Computation for Modular Exponentiation Based on Replicated Secret Sharing.
Kazuma Ohara; Yohei Watanabe 0001; Mitsugu Iwamoto; Kazuo Ohta
Last, IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, IEICE, 102-A, 9, 1079-1090, 01 Sep. 2019, Peer-reviwed
Scientific journal, English - How to improve the private PEZ protocol for general functions,
Yoshiki Abe; Mitsugu Iwamoto; Kazuo Ohta
Advances in Information and Computer Security - The 14th International Workshop on Security (IWSEC2019), poster session, Aug. 2019, Peer-reviwed
International conference proceedings, English - Proceedings of the 11th Asia-Europe Workshop on Concepts in Information Theory.
A. J. Han Vinck; Kees A. Schouhamer Immink; Tadashi Wadayama; Van Khu Vu; Akiko Manada; Kui Cai 0001; Shunsuke Horii; Yoshiki Abe; Mitsugu Iwamoto; Kazuo Ohta; Xingwei Zhong; Zhen Mei; Renfei Bu; Jos H. Weber; Vitaly Skachek; Hiroyoshi Morita; N. Hovhannisyan; Hiroshi Kamabe; Shan Lu 0003; Hirosuke Yamamoto; Kengo Hashimoto; Øyvind Ytrehus; Shigeaki Kuzuoka; Mikihiko Nishiara; Han Mao Kiah; Jun Muramatsu; Shigeki Miyake
CoRR, abs/1907.02944, 2019
Scientific journal - 効率的でフォワード安全な動的検索可能暗号
渡邉洋平; 岩本貢; 太田和夫
SCIS 2019 予稿集, 2019
Symposium, Japanese - (強)フォワード安全な動的検索可能暗号の効率的な構成
渡邉 洋平; 大原一真; 岩本貢; 太田和夫
CSS 2019 予稿集, 2019
Symposium, Japanese - An Abstraction Model for 1-bit Probing Attack on Block Ciphers.
Natsu Shoji; Takeshi Sugawara 0001; Mitsugu Iwamoto; Kazuo Sakiyama
IEEE 4th International Conference on Computer and Communication Systems(ICCCS), IEEE, -, -, 502-506, 2019, Peer-reviwed
International conference proceedings, English - ダミーエントリの作成方法に着目した共通鍵検索可能暗号CGKO方式の改良
野島拓也; 渡邉洋平; 岩本貢; 太田和夫
SCIS 2018 予稿集, 2018
Symposium, Japanese - ロバスト秘密分散法CFOR方式における精密な安全性解析
鈴木慎之介; 渡邉洋平; 岩本貢; 太田和夫
SCIS 2018 予稿集, 2018
Symposium, Japanese - カードを用いた複数人でのマッチングプロトコル
古賀優太; 鈴木慎之介; 渡邉洋平; 岩本貢; 太田和夫
SCIS 2018 予稿集, 2018
Symposium, Japanese - 3枚のカードで実現可能な3入力多数決プロトコル
黒木慶久; 古賀優太; 渡邉洋平; 岩本貢; 太田和夫
SCIS 2018 予稿集, 2018
Symposium, Japanese - 現実的な結託者のもとで最もシェア長の短いロバスト秘密分散法
渡邉洋平; 大原一真; 岩本貢; 太田和夫
ISEC研究会予稿集, 2018
Symposium, Japanese - Card-Based Majority Voting Protocols with Three Inputs Using Three Cards.
Yohei Watanabe 0001; Yoshihisa Kuroki; Shinnosuke Suzuki; Yuta Koga; Mitsugu Iwamoto; Kazuo Ohta
International Symposium on Information Theory and Its Applications(ISITA), IEEE, 218-222, 20 Oct. 2018, Peer-reviwed
International conference proceedings, English - Security Formalizations and Their Relationships for Encryption and Key Agreement in Information-Theoretic Cryptography.
Mitsugu Iwamoto; Kazuo Ohta; Junji Shikata
IEEE Transactions on Information Theory, Institute of Electrical and Electronics Engineers Inc., 64, 1, 654-685, 01 Jan. 2018, Peer-reviwed, This paper analyzes the formalizations of information-theoretic security for the fundamental primitives in cryptography: symmetric-key encryption and key agreement. Revisiting the previous results, we can formalize information-theoretic security using different methods, by extending Shannon’s perfect secrecy, by information-theoretic analogues of indistinguishability and semantic security, and by the frameworks for composability of protocols. We show the relationships among the security formalizations and obtain the following results. First, in the case of encryption, there are significant gaps among the formalizations, and a certain type of relaxed perfect secrecy or a variant of information-theoretic indistinguishability is the strongest notion. Second, in the case of key agreement, there are significant gaps among the formalizations, and a certain type of relaxed perfect secrecy is the strongest notion. In particular, in both encryption and key agreement, the formalization of composable security is not stronger than any other formalizations. Furthermore, as an application of the relationships in encryption and key agreement, we simultaneously derive a family of lower bounds on the size of secret keys and security quantities required under the above formalizations, which also implies the importance and usefulness of the relationships.
Scientific journal, English - Q-Class Authentication System for Double Arbiter PUF.
Risa Yashiro; Takeshi Sugawara 0001; Mitsugu Iwamoto; Kazuo Sakiyama
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Institute of Electronics, Information and Communication, Engineers, IEICE, 101-A, 1, 129-137, 01 Jan. 2018, Peer-reviwed, Physically Unclonable Function (PUF) is a cryptographic primitive that is based on physical property of each entity or Integrated Circuit (IC) chip. It is expected that PUF be used in security applications such as ID generation and authentication. Some responses from PUF are unreliable, and they are usually discarded. In this paper, we propose a new PUF-based authentication system that exploits information of unreliable responses. In the proposed method, each response is categorized into multiple classes by its unreliability evaluated by feeding the same challenges several times. This authentication system is named Q-class authentication, where Q is the number of classes. We perform experiments assuming a challenge-response authentication system with a certain threshold of errors. Considering 4-class separation for 4-1 Double Arbiter PUF, it is figured out that the advantage of a legitimate prover against a clone is improved form 24% to 36% in terms of success rate. In other words, it is possible to improve the tolerance of machine-learning attack by using unreliable information that was previously regarded disadvantageous to authentication systems.
Scientific journal, English - A proactive secret image sharing scheme with resistance to machine learning based steganalysis.
Angelina Espejel Trujillo; Mitsugu Iwamoto; Mariko Nakano-Miyatake
Multimedia Tools and Applications, Springer New York LLC, 77, 12, 15161-15179, 01 Jun. 2018, Peer-reviwed, In secret image sharing (SIS) schemes, a secret image is shared among a set of n images called stego-images. Each stego-image is preserved by a participant. In the recovery stage, at least k out of n stego-images are required to obtain the secret image, while k − 1 cannot reveal the secret in the sense of perfect secrecy. Hence, SIS guarantees long-term security. However, as the longer the stego-images remain stored, the higher is the probability of being vulnerable against steganalysis. To resolve this issue, this paper proposes the use of proactive secret sharing in an SIS scheme (P-SIS). P-SIS allows the stego-images to be renewed frequently while these are stored, without changing both cover and secret images. However, direct implementation of a proactive SIS requires more embedding rate (ER), causing high steganalysis accuracy detection and loss of quality in the stego-images. Our proposal addresses this issue and presents the combination of a (k, L, n)-threshold ramp secret sharing scheme and least significant bit matching (LSBM) steganography to reduce the steganalysis accuracy detection. The results of the evaluation show effectiveness of the proposal in terms of good quality of the stego-images, accurate recovery of the secret, and reduce the ER. Note that, despite the extensive research of SIS presented until now, only a few previous work is found on steganalysis in SIS. Not only constructing P-SIS scheme, but we also experimented the tolerance of the proposed P-SIS scheme against stganalysis in this paper. As a result, it is shown that the proposed scheme can withstand steganalysis based on machine learning (i.e., based on subtractive pixel adjacency matrix, SPAM).
Scientific journal, English - Worst-case guessing secrecy is meaningful in secret sharing schemes
M. Iwamoto
ICITS2017, workshop track, Dec. 2017, Peer-reviwed
International conference proceedings, English - Proceedings of Workshop AEW10: Concepts in Information Theory and Communications.
Kees A. Schouhamer Immink; Stan Baggen; Ferdaous Chaabane; Yanling Chen; Peter H. N. de With; Héla Gassara; Hamed Gharbi; Adel Ghazel; Khaled Grati; Naira M. Grigoryan; Ashot N. Harutyunyan; Masayuki Imanishi; Mitsugu Iwamoto; Ken-ichi Iwata; Hiroshi Kamabe; Brian M. Kurkoski; Shigeaki Kuzuoka; Patrick Langenhuizen; Jan Lewandowsky; Akiko Manada; Shigeki Miyake; Hiroyoshi Morita; Jun Muramatsu; Safa Najjar; Arnak V. Poghosyan; Fatma Rouissi; Yuta Sakai; Ulrich Tamm; Joost van der Putten; Fons van der Sommen; A. J. Han Vinck; Tadashi Wadayama; Dirk Wübben; Hirosuke Yamamoto
CoRR, abs/1707.08567, 2017, Peer-reviwed
Scientific journal - 秘密分散型放送暗号
岩本貢; 渡邉洋平
SCIS 2017 予稿集, 2017
Symposium, Japanese - Four Cards Are Sufficient for a Card-Based Three-Input Voting Protocol Utilizing Private Permutations.
Takeshi Nakai; Satoshi Shirouchi; Mitsugu Iwamoto; Kazuo Ohta
Information Theoretic Security - 10th International Conference(ICITS), Springer, 10681, 153-165, 2017, Peer-reviwed, The card-based cryptographic protocol is a variant of multi-party computation that enables us to compute a certain function securely by using playing cards. In existing card-based cryptographic protocols, a special operation of cards called a shuffle is used to achieve the information-theoretic security. Recently, card-based cryptographic protocols have been reconsidered from the viewpoint of multi-party computations. In this direction, a new model of card-based cryptographic protocol including a new assumption called Private Permutations (PP, for short) is introduced and succeeds in constructing efficient protocols for the millionaires’ protocol. In this paper, we construct efficient card-based cryptographic OR and XOR protocols based on the existing AND protocol. Furthermore, by unifying AND and OR protocols, it is shown that a majority voting protocol with three inputs is efficiently obtained. Our construction requires only four cards thanks to PPs, whereas the previous work requires eight cards.
International conference proceedings, English - Probabilistic Generation of Trapdoors: Reducing Information Leakage of Searchable Symmetric Encryption
K. Hayasaka; Y. Kawai; Y. Koseki; T. Hirano; K. Ohta; M. Iwamoto
CANS2016, Springer-Verlag, 500-517, Nov. 2016, Peer-reviwed
International conference proceedings, English - Application of Joux-Lucks Search Algorithm for Multi-Collisions to MicroMint
Y. Kamoshida; M. Iwamoto
IWSEC2016, poster session, Sep. 2016, Peer-reviwed
International conference proceedings, English - Probabilistic Generation of Trapdoors: Reducing Information Leakage of Searchable Symmetric Encryption.
Kenichiro Hayasaka; Yutaka Kawai; Yoshihiro Koseki; Takato Hirano; Kazuo Ohta; Mitsugu Iwamoto
Cryptology and Network Security - 15th International Conference(CANS), LNCS 10052, Springer-Verlag, 350-364, 14 Nov. 2016, Peer-reviwed
International conference proceedings, English - Efficient Card-Based Cryptographic Protocols for Millionaires' Problem Utilizing Private Permutations.
Takeshi Nakai; Yuuki Tokushige; Yuto Misawa; Mitsugu Iwamoto; Kazuo Ohta
Cryptology and Network Security - 15th International Conference(CANS), LNCS 10052, Springer-Verlag, 500-517, 14 Nov. 2016, Peer-reviwed
International conference proceedings, English - Deep-Learning-Based Security Evaluation on Authentication Systems Using Arbiter PUF and Its Variants.
Risa Yashiro; Takanori Machida; Mitsugu Iwamoto; Kazuo Sakiyama
Advances in Information and Computer Security - 11th International Workshop on Security(IWSEC), Springer, 9836, 267-285, 2016, Peer-reviwed, Fake integrated circuit (IC) chips are in circulation on the market, which is considered a serious threat in the era of the Internet of Things (IoTs). A physically unclonable function (PUF) is expected to be a fundamental technique to separate the fake IC chips from genuine ones. Recently, the arbiter PUF (APUF) and its variants are intensively researched aiming at using for a secure authentication system. However, vulnerability of APUFs against machine-learning attacks was reported. Upon the situation, the double arbiter PUF (DAPUF), which has a tolerance against support vector machine (SVM)-based machine-learning attacks, was proposed as another variant of APUF in 2014. In this paper, we perform a security evaluation for authentication systems using APUF and its variants against Deep-learning (DL)-based attacks. DL has attracted attention as a machine-learning method that produces better results than SVM in various research fields. Based on the experimental results, we show that these DAPUFs could be used as a core primitive in a secure authentication system if setting an appropriate threshold to distinguish a legitimate IC tags from fake ones.
International conference proceedings, English - Simple, Secure, and Efficient Searchable Symmetric Encryption with Multiple Encrypted Indexes.
Takato Hirano; Mitsuhiro Hattori; Yutaka Kawai; Nori Matsuda; Mitsugu Iwamoto; Kazuo Ohta; Yusuke Sakai 0001; Tatsuji Munaka
Advances in Information and Computer Security - 11th International Workshop on Security(IWSEC), Springer, 9836, 91-110, 2016, Peer-reviwed, In searchable symmetric encryption (SSE), adding documents to a database is an indispensable functionality in real situations, and there are two approaches for executing the process: One approach is to update the encrypted index, and the other is to generate a new encrypted index. The former approach is called dynamic SSE, which has been extensively studied recently due to its importance. The latter approach has an advantage such that it can be directly applied to any existing SSE scheme without degrading its original functionalities, but previous methods are not satisfactory from a viewpoint of security, storage size, or efficiency. In this paper, we propose a simple document adding method that resolve the problem occurred in the latter approach. Our method is quite generic, and therefore can be applied to any existing SSE scheme (e.g. non-dynamic one with useful functionalities). Our key idea is to utilize publicly available information and hash chains in construction of encrypted indexes. In order to exhibit the ability of our method, we present a concrete scheme which is led by applying our method to the well-known and influential scheme SSE-2 ( ACM CCS 2006). Thanks to the simplicity of our method, the scheme can be easily proved secure under a naturally generalized setting of the most widely used security model.
International conference proceedings, English - Efficient Card-Based Cryptographic Protocols for Millionaires' Problem Utilizing Private Permutations.
Takeshi Nakai; Yuuki Tokushige; Yuto Misawa; Mitsugu Iwamoto; Kazuo Ohta
Cryptology and Network Security - 15th International Conference(CANS), Springer-Verlag, 500-517, Nov. 2016, Peer-reviwed
International conference proceedings, English - Toward Reducing Shuffling in Card-based Cryptographic Protocol for Millionaire Problem
T. Nakai; Y. Tokushige; M. Iwamoto; K. Ohta
International Workshop on Information Security and Crytptograohy, poster session, Aug. 2015, Peer-reviwed
International conference proceedings, English - Comparison of Security on Coded Signs with Public/Private Code Book
Y. Misawa; Y. Tokushige; M. Iwamoto; K. Ohta
International Workshop on Information Security and Crytptograohy, poster session, Aug. 2015, Peer-reviwed
International conference proceedings, English - 推測確率に基づいた安全性基準をみたす暗号化方式の構成法
岩本貢; 四方順司
暗号と情報セキュリティシンポジウム 2015 (SCIS 2015), 2D1-5, Jan. 2015
Japanese - Constructions of symmetric-key encryption with guessing secrecy.
Mitsugu Iwamoto; Junji Shikata
IEEE International Symposium on Information Theory(ISIT), IEEE, 725-729, 2015, Peer-reviwed, Constructions of symmetric-key encryption with guessing secrecy are discussed. In the previous works, only a construction of symmetric-key encryption with average guessing secrecy is proposed for one-bit plaintexts. In this paper, we analyze a symmetric-key encryption with average guessing secrecy through OTP (one-time pad) constructions for a wide class of probability distributions of plaintexts and keys. As a result, we show a necessary and sufficient condition that such class of distributions satisfies average guessing secrecy in OTP constructions. On the other hand, we prove that optimal guessing secrecy is essentially equivalent to perfect secrecy under several natural restrictions. Therefore, only average guessing secrecy is meaningful for considering guessing secrecy other than perfect secrecy.
International conference proceedings, English - Implementation of double arbiter PUF and its performance evaluation on FPGA.
Takanori Machida; Dai Yamamoto; Mitsugu Iwamoto; Kazuo Sakiyama
The 20th Asia and South Pacific Design Automation Conference(ASP-DAC), IEEE, 6-7, 2015, Peer-reviwed, Low uniqueness and vulnerability to machine-learning attacks are known as two major problems of Arbiter-Based Physically Unclonable Function (APUF) implemented on FPGAs. In this paper, we implement Double APUF (DAPUF) that duplicates the original APUF in order to overcome the problems. From the experimental results on Xilinx Virtex-5, we show that the uniqueness of DAPUF becomes almost ideal, and the prediction rate of the machine-learning attack decreases from 86% to 57%.
International conference proceedings, English - A New Arbiter PUF for Enhancing Unpredictability on FPGA
Takanori Machida; Dai Yamamoto; Mitsugu Iwamoto; Kazuo Sakiyama
Scientific World Journal, Hindawi Publishing Corporation, 2015, 864812, 2015, Peer-reviwed, In general, conventional Arbiter-based Physically Unclonable Functions (PUFs) generate responses with low unpredictability. The N-XOR Arbiter PUF, proposed in 2007, is a well-known technique for improving this unpredictability. In this paper, we propose a novel design for Arbiter PUF, called Double Arbiter PUF, to enhance the unpredictability on field programmable gate arrays (FPGAs), and we compare our design to conventional N-XOR Arbiter PUFs. One metric for judging the unpredictability of responses is to measure their tolerance to machine-learning attacks. Although our previous work showed the superiority of Double Arbiter PUFs regarding unpredictability, its details were not clarified. We evaluate the dependency on the number of training samples for machine learning, and we discuss the reason why Double Arbiter PUFs are more tolerant than the N-XOR Arbiter PUFs by evaluating intrachip variation. Further, the conventional Arbiter PUFs and proposed Double Arbiter PUFs are evaluated according to other metrics, namely, their uniqueness, randomness, and steadiness. We demonstrate that 3-1 Double Arbiter PUF archives the best performance overall.
Scientific journal, English - A new method for enhancing variety and maintaining reliability of PUF responses and its evaluation on ASICs.
Dai Yamamoto; Kazuo Sakiyama; Mitsugu Iwamoto; Kazuo Ohta; Masahiko Takenaka; Kouichi Itoh; Naoya Torii
Journal of Cryptographic Engineering, 5, 3, 187-199, 2015, Peer-reviwed
Scientific journal, English - A New Model of Client--Server Communications under Information Theoretic Security
M. Iwamoto; T. Omino; Y. Komano; K. Ohta
IEEE Information Thoery Workshop 2014, IEEE, 512-516, Nov. 2014, Peer-reviwed
International conference proceedings, English - クロック間衝突を漏洩モデルとする新たなサイドチャネル解析と並列実装AES暗号ハードウェアにおける弱い鍵
Toshiki Nakasone; Yang Li; Mitsugu Iwamoto; Kazuo Ohta; Kazuo Sakiyama
IEICE Trans. JA, J97-A, 11, 695-703, Nov. 2014, Peer-reviwed
Scientific journal, Japanese - A New Mode of Operation for Arbiter PUF to Improve Uniqueness on FPGA
T.Machida; D.Yamamoto; M.Iwamoto; K.Sakiyama
1st Workshop on Emerging Aspects in Information Security (EAIS'14), 877-884, Sep. 2014, Peer-reviwed
International conference proceedings, English - Optimal Constructions for Information Theoretically Secure Encryptions Based on Renyi Entropies
M. Iwamoto; J. Shikata
Proc. of The 31th Symposium on Cryptography and Information Security (SCIS 2014), 1E2-3, 21 Jan. 2014
English - A new model of Client-Server Communications under information theoretic security.
Mitsugu Iwamoto; Tsukasa Omino; Yuichi Komano; Kazuo Ohta
2014 IEEE Information Theory Workshop(ITW), IEEE, 511-515, 2014, Peer-reviwed, A new model for a Client-Server Communication (CSC) system satisfying information theoretic security is proposed, and its fundamental properties are discussed. Our CSC allows n users to upload their respective messages to a server securely by using symmetric key encryptions with their own keys, and all ciphertexts are decrypted by the server.
If we require all messages to be perfectly secure in CSC against the corrupted clients and adversaries without any keys, it is proved that a one time pad or more inefficient encryption must be used for each communication link between a client and the server. This means that, in order to realize more efficient CSC, it is necessary to leak out some information of each message. Based on these observations, we introduce a new model for such a secure CSC formally, and discuss its fundamental properties. In addition, we propose the optimal construction of CSC under several constraints on security parameters called security rates.
International conference proceedings, English - A New Mode of Operation for Arbiter PUF to Improve Uniqueness on FPGA.
Takanori Machida; Dai Yamamoto; Mitsugu Iwamoto; Kazuo Sakiyama
Proceedings of the 2014 Federated Conference on Computer Science and Information Systems(FedCSIS), IEEE, 2, 871-878, 2014, Peer-reviwed, Arbiter-based Physically Unclonable Function (PUF) is one kind of the delay-based PUFs that use the time difference of two delay-line signals. One of the previous work suggests that Arbiter PUFs implemented on Xilinx Virtex-5 FPGAs generate responses with almost no difference, i.e. with low uniqueness. In order to overcome this problem, Double Arbiter PUF was proposed, which is based on a novel technique for generating responses with high uniqueness from duplicated Arbiter PUFs on FPGAs. It needs the same costs as 2-XOR Arbiter PUF that XORs outputs of two Arbiter PUFs. Double Arbiter PUF is different from 2-XOR Arbiter PUF in terms of mode of operation for Arbiter PUF: the wire assignment between an arbiter and output signals from the final selectors located just before the arbiter. In this paper, we evaluate these PUFs as for uniqueness, randomness, and steadiness. We consider finding a new mode of operation for Arbiter PUF that can be realized on FPGA. In order to improve the uniqueness of responses, we propose 3-1 Double Arbiter PUF that has another duplicated Arbiter PUF, i.e. having 3 Arbiter PUFs and output 1-bit response. We compare 3-1 Double Arbiter PUF to 3-XOR Arbiter PUF according to the uniqueness, randomness, and steadiness, and show the difference between these PUFs by considering the mode of operation for Arbiter PUF. From our experimental results, the uniqueness of responses from 3-1 Double Arbiter PUF is approximately 50%, which is better than that from 3-XOR Arbiter PUF. We show that we can improve the uniqueness by using a new mode of operation for Arbiter PUF.
International conference proceedings, English - Secure (M+1) st-Price Auction with Automatic Tie-Break.
Takashi Nishide; Mitsugu Iwamoto; Atsushi Iwasaki; Kazuo Ohta
Trusted Systems - 6th International Conference(INTRUST), Springer, 9473, 422-437, 2014, Peer-reviwed, In auction theory, little attention has been paid to a situation where the tie-break occurs because most of auction properties are not affected by the way the tie-break is processed. Meanwhile, in secure auctions where private information should remain hidden, the information of the tie can unnecessarily reveal something that should remain hidden. Nevertheless, in most of existing secure auctions, ties are handled outside the auctions, and all the winning candidates or only the non-tied partial bidders are identified in the case of ties, assuming that a subsequent additional selection (or auction) to finalize the winners is held publicly. However, for instance, in the case of the (M + 1) st-price auction, the tied bidders in the (M + 1) st-price need to be identified for such a selection, which implies that their bids (unnecessary private information) are revealed. Hence it is desirable that secure auctions reveal neither the existence of ties nor the losing tied bidders.
To overcome these shortcomings, we propose a secure (M + 1) st-price auction protocol with automatic tie-breaks and no leakage of the tie information by improving the bit-slice auction circuit without increasing much overhead.
International conference proceedings, English - Cheating on a visual secret sharing scheme under a realistic scenario.
Pichanee Lumyong; Mitsugu Iwamoto; Kazuo Ohta
International Symposium on Information Theory and its Applications(ISITA), IEEE, 575-579, 2014, Peer-reviwed, Cheating on a (2, n)-threshold visual secret sharing (VSS) schemes is discussed under a realistic scenario. Horng et al. pointed out an ordinary VSS scheme is vulnerable against a certain kind of cheating, and they proposed a countermeasure against it. In their work, so-called Kerckhoffs's principle and availability of computing power are implicitly assumed in cheating detection. Namely, this work follows a scenario where a victim knows basis matrices and can use computational ability in cheating detection. Under this scenario, Horng et al. showed that their countermeasure attains negligible success probability of generating the victim's share. However, recalling the fact that the decryption of VSS schemes does not depend on computations but depends on human visual system, we can naturally assume a realistic scenario where the victim does not know the basis matrices and has no computing power. Under this scenario, we show that the cheaters can make the victim recover an arbitrary forged secret image in Horng et al.'s countermeasure with probability 1.
International conference proceedings, English - Secret Sharing Schemes Based on Min-Entropies.
Mitsugu Iwamoto; Junji Shikata
CoRR, IEEE, abs/1401.5896, 401-405, 2014, Peer-reviwed, Fundamental results on secret sharing schemes (SSSs) are discussed in the setting where security and share size are measured by (conditional) min-entropies.
We first formalize a unified framework of SSSs based on (conditional) Renyi entropies, which includes SSSs based on Shannon and min entropies etc. as special cases. By deriving the lower bound of share sizes in terms of Renyi entropies based on the technique introduced by Iwamoto-Shikata, we obtain the lower bounds of share sizes measured by min entropies as well as by Shannon entropies in a unified manner.
As the main contributions of this paper, we show two existential results of non-perfect SSSs based on min-entropies under several important settings. We first show that there exists a non-perfect SSS for arbitrary binary secret information and arbitrary monotone access structure. In addition, for every integers k and n (k <= n), we prove that the ideal non-perfect (k; n)-threshold scheme exists even if the distribution of the secret is not uniformly distributed.
Scientific journal, English - Privacy-preserving smart metering with verifiability for both billing and energy management.
Kazuma Ohara; Yusuke Sakai 0001; Fumiaki Yoshida; Mitsugu Iwamoto; Kazuo Ohta
ASIAPKC'14(AsiaPKC@AsiaCCS), ACM, 23-32, 2014, Peer-reviwed, In smart grid systems, security and privacy prevention is great concerns. The suppliers of the power in smart grid systems demand to know the consumption of each customer for correctly calculating billing price and the total amount of consumption in a certain region for managing energy supply adopted real-time needs. On the other hand, the customer of the power desires to hide his/her own consumption profile, since it contains privacy information of the customer. However, hiding the consumption allows customers to reduce billing price. Previous privacy-preserving smart metering schemes provide only one of billing or energy management functionality, or even if both of them are achieved, these schemes cannot verify the integrity of the consumption issued by the smart meter. We propose a novel smart metering scheme that provides both of billing and energy management functionality, as well as verifiability of the integrity of total amount of the consumption or billing price. © 2014 ACM.
International conference proceedings, English - An Automated Evaluation Tool for Improved Rebound Attack: New Distinguishers and Proposals of ShiftBytes Parameters for Grøstl.
Yu Sasaki; Yuuki Tokushige; Lei Wang 0031; Mitsugu Iwamoto; Kazuo Ohta
Topics in Cryptology - CT-RSA 2014 - The Cryptographer's Track at the RSA Conference 2014(CT-RSA), Springer, 8366, 424-443, 2014, Peer-reviwed, In this paper, we study the security of AES-like permutations against the improved rebound attack proposed by Jean et al. at FSE 2012 which covers three full-active rounds in the inbound phase. The attack is very complicated and hard to verify its optimality when the state size is large and rectangle, namely the numbers of rows and columns are different. In the inbound phase of the improved rebound attack, several SuperSBoxes are generated for each of forward analysis and backward analysis. The attack searches for paired values that are consistent with all SuperSBoxes. The attack complexity depends on the order of the SuperSBoxes to be analyzed, and detecting the best order is hard. In this paper, we develop an automated complexity evaluation tool with several fast implementation techniques. The tool enables us to examine all the possible orders of the SuperSBoxes, and provides the best analysis order and complexity. We apply the tool to large block Rijndael in the known-key setting and the Grøstl-512 permutation. As a result, we obtain the first 9-round distinguisher for Rijndael-192 and Rijndael-224. It also shows the impossibility of the improved rebound attack against 9-round Rijndael-160 and 10-round Rijndael-256, and the optimality of the previous distinguisher against the 10-round Grøstl-512 permutation. Moreover, the efficiency of the improved rebound attack depends on the parameter of the ShiftRows operation. Our tool can exhaustively examine all the possible ShiftRows parameters to search for the ones that can resist the attack. We show new parameters for the Grøstl-512 permutation obtained by our tool, which can resist a 10-round improved rebound attack while the specification parameter cannot resist it. © 2014 Springer International Publishing.
International conference proceedings, English - Practical DFA Strategy for AES Under Limited-access Conditions.
Kazuo Sakiyama; Yang Li 0001; Shigeto Gomisawa; Yu-ichi Hayashi; Mitsugu Iwamoto; Naofumi Homma; Takafumi Aoki; Kazuo Ohta
Journal of Information Processing, Information Processing Society of Japan, 22, 2, 142-151, 2014, Peer-reviwed, Secret data in embedded devices can be revealed by injecting computational faults using the fault analysis attacks. The fault analysis researches on a cryptographic implementation by far first assumed a certain fault model, and then discussed the key recovery method under some assumptions. We note that a new remote-fault injection method has emerged, which is threatening in practice. Due to its limited accessibility to cryptographic devices, the remotefault injection, however, can only inject uncertain faults. In this surroundings, this paper gives a general strategy of the remote-fault attack on the AES block cipher with a data set of faulty ciphertexts generated by uncertain faults. Our method effectively utilizes all the information from various kinds of faults, which is more realistic than previous researches. As a result, we show that it can provide a decent success probability of key identification even when only a few intended faults are available among 32 millions fault injections. © 2014 Information Processing Society of Japan.
Scientific journal, English - Revisiting Conditional Renyi Entropy and its Application to Encryption: Part I --Properties of Conditional Renyi Entropy--
M. Iwamoto; J. Shikata
Proc. of The 30th Symposium on Cryptography and Information Security (SCIS 2013), 22 Jan. 2013
English - Revisiting Conditional Renyi Entropy and its Application to Encryption: Part II --Fano's Inequality and Shannon's Bound--
J. Shikata; M. Iwamoto
Proc. of The 30th Symposium on Cryptography and Information Security (SCIS 2013), 22 Jan. 2013
English - Limited-Birthday Distinguishers for Hash Functions - Collisions beyond the Birthday Bound Can Be Meaningful.
Mitsugu Iwamoto; Thomas Peyrin; Yu Sasaki
Advances in Cryptology - ASIACRYPT 2013 - 19th International Conference on the Theory and Application of Cryptology and Information Security, Springer, 8270, 504-523, 2013, Peer-reviwed, In this article, we investigate the use of limited-birthday distinguishers to the context of hash functions. We first provide a proper understanding of the limited-birthday problem and demonstrate its soundness by using a new security notion Differential Target Collision Resistance (dTCR) that is related to the classical Target Collision Resistance (TCR) notion. We then solve an open problem and close the existing security gap by proving that the best known generic attack proposed at FSE 2010 for the limited-birthday problem is indeed the best possible method.
Moreover, we show that almost all known collision attacks are in fact more than just a collision finding algorithm, since the difference mask for the message input is usually fixed. A direct and surprising corollary is that these collision attacks are interesting for cryptanalysis even when their complexity goes beyond the 2(n/2) birthday bound and up to the 2(n) preimage bound, and can be used to derive distinguishers using the limited-birthday problem. Interestingly, cryptanalysts can now search for collision attacks beyond the 2(n/2) birthday bound. Finally, we describe a generic algorithm that turns a semi-free-start collision attack on a compression function (even if its complexity is beyond the birthday bound) into a distinguisher on the whole hash function when its internal state is not too wide. To the best of our knowledge, this is the first result that exploits classical semi-free-start collisions on the compression function to exhibit a weakness on the whole hash function. As an application of our findings, we provide distinguishers on reduced or full version of several hash functions, such as RIPEMD-128, SHA-256, Whirlpool, etc.(I)n this article, we investigate the use of limited-birthday distinguishers to the context of hash functions. We first provide a proper understanding of the limited-birthday problem and demonstrate its soundness by using a new security notion Differential Target Collision Resistance (dTCR) that is related to the classical Target Collision Resistance (TCR) notion. We then solve an open problem and close the existing security gap by proving that the best known generic attack proposed at FSE 2010 for the limited-birthday problem is indeed the best possible method. Moreover, we show that almost all known collision attacks are in fact more than just a collision finding algorithm, since the difference mask for the message input is usually fixed. A direct and surprising corollary is that these collision attacks are interesting for cryptanalysis even when their complexity goes beyond the 2(n/2) birthday bound and up to the 2(n) preimage bound, and can be used to derive distinguishers using the limited-birthday problem. Interestingly, cryptanalysts can now search for collision attacks beyond the 2(n/2) birthday bound.
Finally, we describe a generic algorithm that turns a semi-free-start collision attack on a compression function (even if its complexity is beyond the birthday bound) into a distinguisher on the whole hash function when its internal state is not too wide. To the best of our knowledge, this is the first result that exploits classical semi-free-start collisions on the compression function to exhibit a weakness on the whole hash function. As an application of our findings, we provide distinguishers on reduced or full version of several hash functions, such as RIPEMD-128, SHA-256, Whirlpool, etc.
International conference proceedings, English - Information Theoretic Security for Encryption Based on Conditional Rényi Entropies.
Mitsugu Iwamoto; Junji Shikata
Information Theoretic Security - 7th International Conference(ICITS), Springer, 8317, 103-121, 2013, Peer-reviwed, In this paper, information theoretic cryptography is discussed based on conditional Renyi entropies. Our discussion focuses not only on cryptography but also on the definitions of conditional Renyi entropies and the related information theoretic inequalities. First, we revisit conditional Renyi entropies, and clarify what kind of properties are required and actually satisfied. Then, we propose security criteria based on Renyi entropies, which suggests us deep relations between (conditional) Renyi entropies and error probabilities by using several guessing strategies. Based on these results, unified proof of impossibility, namely, the lower bounds on key sizes are derived based on conditional Renyi entropies. Our model and lower bounds include the Shannon's perfect secrecy, and the min-entropy based encryption presented by Dodis, and Alimomeni and Safavi-Naini at ICIT52012. Finally, a new optimal symmetric key encryption protocol achieving the lower bounds is proposed.
International conference proceedings, English - A New Model of Modeling Attacks against Arbiter PUF on FPGA
T. Machida; T. Nakasone; M. Iwamoto; K. Sakiyama
International Workshop on Information Security and Crytptograohy, poster session, 2013, Peer-reviwed
International conference proceedings, English - Meet-in-the-Middle Preimage Attacks Revisited - New Results on MD5 and HAVAL.
Yu Sasaki; Wataru Komatsubara; Yasuhide Sakai; Lei Wang 0031; Mitsugu Iwamoto; Kazuo Sakiyama; Kazuo Ohta
SECRYPT 2013 - Proceedings of the 10th International Conference on Security and Cryptography(SECRYPT), SciTePress, 111-122, Jul. 2013, Peer-reviwed
International conference proceedings, English - Variety enhancement of PUF responses using the locations of random outputting RS latches.
Dai Yamamoto; Kazuo Sakiyama; Mitsugu Iwamoto; Kazuo Ohta; Masahiko Takenaka; Kouichi Itoh
Journal of Cryptographic Engineering, 3, 4, 197-211, Nov. 2013, Peer-reviwed, Physical Unclonable Functions (PUFs) are expected to represent an important solution for secure ID generation and authentication etc. In general, manufactured PUFs are considered to be more secure when the pattern of outputs (the variety of responses) is larger, i.e., the response bit length is longer (e.g., 192-bit response is more secure than 128-bit one). However, the actual bit length is reduced because some response bits are inconsistent (random) for repeated measurements, which are regarded as unnecessary for ID generation and discarded. Latch-based PUFs with N RS latches, for example, generate ideally 2N responses depending on binary values output from RS latches (0/1). However, some RS latches output random responses which are inconsistent and cannot be used for reliable ID generation, so the variety of responses becomes smaller than 2N. In this paper, we propose a novel Latch-based PUF structure, which outputs larger variety of responses by utilizing location information of the RS latches outputting the random responses. Differently from random responses themselves, this location information is determined during a manufacturing process, so almost fixed once PUFs are manufactured. The proposed PUF generates 3N ≈ 21.58N responses by considering random responses as the third stable value: using ternary values (0/1/random). We estimate the variety of responses generated by the proposed PUFs. According to our experiment with 40 FPGAs, a Latch-based PUF with 128 RS latches can improve it from 2116 to 2192.7, this being maximized when the 128 latches outputs 0s, 1s, or random outputs with equal probability. We also show the appropriate RS latch structure for satisfying this condition, and validate it using two kinds of different Xilinx FPGAs: Spartan-3E and Spartan-6. The average error rate of responses is only 5.3 % when the core voltage is changed within the rated voltage range of the FPGAs. Our proposed PUF using ternary values enhances dramatically the variety of responses while keeping the reliability. © 2012 The Author(s).
Scientific journal, English - A t-resilient Unconditionally Secure First-Price Auction Protocol
K.Ohara; Y.Sakai; M.Iwamoto; K.Ohta
International Workshop on Information Security and Crytptograohy, poster session, Nov. 2012, Peer-reviwed
International conference proceedings, English - Coding Theorems for a (2, 2)-Threshold Scheme With Detectability of Impersonation Attacks.
Mitsugu Iwamoto; Hiroki Koga; Hirosuke Yamamoto
IEEE Transactions on Information Theory, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 58, 9, 6194-6206, Sep. 2012, Peer-reviwed, Coding theorems on a (2, 2) -threshold scheme with an opponent are discussed in an asymptotic setup, where the opponent tries to impersonate one of the two participants. A situation is considered where n secrets S-n from a memoryless source is blockwisely encoded to two shares and the two shares are decoded to S-n with permitting negligible decoding error. We introduce correlation level of the two shares and characterize the minimum attainable rates of the shares and a uniform random number for realizing a -threshold scheme that is secure against the impersonation attack by the opponent. It is shown that if the correlation level between the two shares equals to l >= 0, the minimum attainable rates coincide with H(S) + l, where H(S) denotes the entropy of the source, and the maximum attainable exponent of the success probability of the impersonation attack equals to l. It is also shown that a simple scheme using an ordinary (2, 2)-threshold scheme attains all the bounds as well.
Scientific journal, English - A cheating prevention EVC scheme using watermarking techniques
Angelina Espejel Trujillo; Mariko Nakano Miyatake; Mitsugu Iwamoto; Hector Perez Meana
REVISTA FACULTAD DE INGENIERIA-UNIVERSIDAD DE ANTIOQUIA, IMPRENTA UNIV ANTIOQUIA, 63, 63, 30-42, Jun. 2012, Peer-reviwed, Visual Cryptography (VC), proposed by Naor and Shamir in 1994, is a variation of the conventional secret sharing scheme. In VC, instead of a numerical secret key, a secret image is shared among participants in the form of images called shares. Each participant possesses his own share which cannot reveal the secret image being alone, making it necessary to stack more than one share of a qualified participant in order to reveal the secret image. Thus in VC the stacking of shares is equivalent to the decryption process, where neither extra computations nor previous knowledge are required to reveal the secret image. Until now some important VC schemes, such as the (k,n)-VC scheme, the general access structure for VC and the extended VC (EVC), have been proposed. Unfortunately all schemes can be cheated, if one or more participants try to generate their fake shares to force the revealed secret image to be a faked one. In this paper, we propose a cheating prevention VC scheme, in which the shares can be identified and authenticated using the EVC scheme and watermarking techniques. In the proposed VC scheme, the share of each participant can be identified by its meaningful appearance instead of noise-like image used in the conventional VC scheme. For the purpose of authentication of each share two binary watermark images are encrypted using shift operation. Before the secret image is revealed, the validation of the shares must be carried out, extracting two watermark images. If they can be extracted correctly, the revealed secret image is considered as authentic; otherwise it is determined as a faked one. The simulation results show the desirable performance of the proposed EVC scheme.
Scientific journal, English - Key-Dependent Weakness of AES-Based Ciphers under Clockwise Collision Distinguisher.
Toshiki Nakasone; Yang Li 0001; Yu Sasaki; Mitsugu Iwamoto; Kazuo Ohta; Kazuo Sakiyama
Information Security and Cryptology - ICISC 2012 - 15th International Conference(ICISC), Springer, 7839, 395-409, 2012, Peer-reviwed, In 2011, Li et al. proposed a series of side-channel attacks that are related to a fundamental side-channel leakage source called clockwise collision. This paper discloses the fact that hardware implementations of AES-based ciphers could have weak keys assuming that the leakage of clockwise collision is distinguishable. In order to explain this, we firstly set up an evaluation method by introducing a threshold-based distinguisher that takes an advantage of the locality of ElectroMagnetic (EM) measurements. Secondly, we discuss that the probability of clockwise collision depends on the key values and the byte positions in the AES states. Thirdly, based on practical EM measurements and mathematical analysis, we quantitatively evaluate the relationship between the probability of clockwise collision and the vulnerability to the side-channel attack. Finally, the discussion is extended to the design methodology of AES-based ciphers, i.e., the parameter selection for S-box and ShiftRows. © 2013 Springer-Verlag.
International conference proceedings, English - Variations of Information Theoretic Security Notions
M. Iwamoto; K. Ohta
Asian-Europian Workshop on Information Theory (AEW), 73-77, Jul. 2011, Peer-reviwed
International conference proceedings, English - Uniqueness Enhancement of PUF Responses Based on the Locations of Random Outputting RS Latches.
Dai Yamamoto; Kazuo Sakiyama; Mitsugu Iwamoto; Kazuo Ohta; Takao Ochiai; Masahiko Takenaka; Kouichi Itoh
Cryptographic Hardware and Embedded Systems - CHES 2011 - 13th International Workshop(CHES), Springer, 6917, 390-406, 2011, Peer-reviwed, Physical Unclonable Functions (PUFs) are expected to represent an important solution for secure ID generation and authentication etc. In general, PUFs are considered to be more secure the larger their output entropy. However, the entropy of conventional PUFs is lower than the output bit length, because some output bits are random numbers, which are regarded as unnecessary for ID generation and discarded. We propose a novel PUF structure based on a Butterfly PUF with multiple RS latches, which generates larger entropy by utilizing location information of the RS latches generating random numbers. More specifically, while conventional PUFs generate binary values (0/1), the proposed PUF generates ternary values (0/1/random) in order to increase entropy. We estimate the entropy of the proposed PUF. According to our experiment with 40 FPGAs, a Butterfly PUF with 128 RS latches can improve entropy from 116 bits to 192.7 bits, this being maximized when the frequency of each ternary value is equal. We also show the appropriate RS latch structure for satisfying this condition, and validate it through an FPGA experiment.
International conference proceedings, English - Security notions for information theoretically secure encryptions.
Mitsugu Iwamoto; Kazuo Ohta
2011 IEEE International Symposium on Information Theory Proceedings(ISIT), IEEE, abs/1106.1731, 1777-1781, 2011, Peer-reviwed, This paper is concerned with several security notions for information theoretically secure encryptions defined by the variational (statistical) distance. To ensure the perfect secrecy (PS), the mutual information is often used to evaluate the statistical independence between a message and a cryptogram. On the other hand, in order to recognize the information theoretically secure encryptions and computationally secure ones comprehensively, it is necessary to reconsider the notion of PS in terms of the variational distance. However, based on the variational distance, three kinds of definitions for PS are naturally introduced, but their relations are not known. In this paper, we clarify that one of three definitions for PS with the variational distance, which is a straightforward extension of Shannon's perfect secrecy, is stronger than the others, and the weaker two definitions of PS are essentially equivalent to the statistical versions of indistinguishability and semantic security.
International conference proceedings, English - Security Notions for Information Theoretically Secure Encryptions
Mitsugu Iwamoto; Kazuo Ohta
CoRR, IEEE, abs/1106.1731, 1777-1781, 2011, Peer-reviwed, This paper is concerned with several security notions for information theoretically secure encryptions defined by the variational (statistical) distance. To ensure the perfect secrecy (PS), the mutual information is often used to evaluate the statistical independence between a message and a cryptogram. On the other hand, in order to recognize the information theoretically secure encryptions and computationally secure ones comprehensively, it is necessary to reconsider the notion of PS in terms of the variational distance. However, based on the variational distance, three kinds of definitions for PS are naturally introduced, but their relations are not known. In this paper, we clarify that one of three definitions for PS with the variational distance, which is a straightforward extension of Shannon's perfect secrecy, is stronger than the others, and the weaker two definitions of PS are essentially equivalent to the statistical versions of indistinguishability and semantic security. © 2011 IEEE.
Scientific journal, English - Uniqueness Enhancement of PUF Responses Based on the Locations of Random Outputting RS Latches.
Dai Yamamoto; Kazuo Sakiyama; Mitsugu Iwamoto; Kazuo Ohta; Takao Ochiai; Masahiko Takenaka; Kouichi Itoh
Cryptographic Hardware and Embedded Systems - CHES 2011 - 13th International Workshop(CHES), Springer, 6917, 390-406, 2011, Peer-reviwed, Physical Unclonable Functions (PUFs) are expected to represent an important solution for secure ID generation and authentication etc. In general, PUFs are considered to be more secure the larger their output entropy. However, the entropy of conventional PUFs is lower than the output bit length, because some output bits are random numbers, which are regarded as unnecessary for ID generation and discarded. We propose a novel PUF structure based on a Butterfly PUF with multiple RS latches, which generates larger entropy by utilizing location information of the RS latches generating random numbers. More specifically, while conventional PUFs generate binary values (0/1), the proposed PUF generates ternary values (0/1/random) in order to increase entropy. We estimate the entropy of the proposed PUF. According to our experiment with 40 FPGAs, a Butterfly PUF with 128 RS latches can improve entropy from 116 bits to 192.7 bits, this being maximized when the frequency of each ternary value is equal. We also show the appropriate RS latch structure for satisfying this condition, and validate it through an FPGA experiment.
International conference proceedings, English - Visual Secret Sharing Schemes for Multiple Secret Images Including Shifting Operation of Shares
A. Espejel-Trujillo; M. Nakano-Miyatake; M. Iwamoto
Proc. of 6th International Conference on Electrical Engineering, Computing Science and Automatic Control, IEEE, 443-438, Nov. 2009, Peer-reviwed
International conference proceedings, English - Visual secret sharing schemes allowing arbitrary rotation angles of shares
Yang Li; Mitsugu Iwamoto; Kazuo Ohta; Kazuo Sakiyama
TriSAI 2009 - Proceedings of Triangle Symposium on Advanced ICT 2009, 33-38, 2009, In 2006, Iwamoto et al. introduced a visual secret sharing (VSS) scheme that allows rotation operation for shares in decryption. However, their construction is complicated and it only deals with 180-degree rotation. In this paper, based on the change of the expression of subpixels, the rotation angle for shares is extended into degrees besides 180-degree. Specifically, this paper proposed a new VSS scheme, in which two shares can decrypt multiple secret images with appropriate rotation angles. Our construction approach also overcomes the shortcomings of the one proposed by Li et al. It satisfies the information theoretical security and is simpler than previous works. Besides, it is also possible to extend the proposed schemes into n shares.
International conference proceedings, English - A coding theorem for cheating-detectable (2, 2)-threshold blockwise secret sharing schemes.
Mitsugu Iwamoto; Hirosuke Yamamoto; Hiroki Koga
IEEE International Symposium on Information Theory(ISIT), IEEE, 1308-1312, 2009, Peer-reviwed, It is known that a secret sharing scheme (SSS) with perfect cheating detection cannot be realized because such a SSS requires infinite share rates. However, this impossibility comes from the fact that block coding is not used and any decoding error is not allowed in the SSS. Hence, in this paper, we consider a SSS constructed by block coding with an arbitrarily small decoding error probability. It is shown that the perfect cheating detection with finite rates is possible for the 2-out-of-2 SSS in a certain asymptotic sense. Furthermore, the supremum of the achievable exponent in the maximum success probability of impersonation attack turns out to be the mutual information between the two shares.
International conference proceedings, English - Coding Theorems for a (2,2)-Threshold Scheme Secure against Impersonation by an Opponent
Hiroki Koga; Mitsugu Iwamoto; Hirosuke Yamamoto
2009 IEEE INFORMATION THEORY WORKSHOP (ITW 2009), IEEE, 188-192, 2009, Peer-reviwed, In this paper, we focus on a (2,2)-threshold scheme in the presence of an opponent who impersonates one of the two participants. We consider an asymptotic setting where two shares are generated by an encoder blockwisely from an n-tuple of secrets generated from a stationary memoryless source and a uniform random number available only to the encoder. We introduce a notion of correlation level of the two shares and give coding theorems on the rates of the shares and the uniform random number. It is shown that, for any (2,2)-threshold scheme with correlation level r, none of the rates can be less than H (S)+r, where H (S) denotes the entropy of the source. We also show that the impersonation by the opponent is successful with probability at least 2(-nr+o(n)). In addition, we prove the existence of an encoder and a decoder of the (2,2)-threshold scheme that asymptotically achieve all the bounds on the rates and the success probability of the impersonation.
International conference proceedings, English - Weakly Secure Visual Secret Sharing Schemes
Mitsugu Iwamoto
2008 INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY AND ITS APPLICATIONS, VOLS 1-3, IEEE, 41-46, 2008, Peer-reviwed, We introduce a visual secret sharing (VSS) scheme with a new security condition, called a weakly secure VSS scheme, which is not unconditionally secure in general, but is designed to be secure for human eyesight. It is shown in this paper that the weakly secure VSS scheme is equivalent to the unconditional one for black-white binary secret images although they are different for color secret images. This fact implies that, at the sacrifice of security, the cleaxer color images can be reproduced by the weakly secure VSS schemes compared with the unconditional ones. Furthermore, some constructions of weakly secure VSS schemes axe presented.
International conference proceedings, English - A Remark on Visual Secret Sharing Schemes Allowing the Rotation of Shares
M. Iwamoto; L. Wang; K. Yoneyama; N. Kunihiro; K. Ohta
5th Asia-Europe workshop on information theory, SITA, 37-42, Oct. 2006
International conference proceedings, English - Visual Secret Sharing Schemes for Multiple Secret Images Allowing the Rotation of Shares
Mitsugu Iwamoto; Lei Wang; Kazuki Yoneyama; Noboru Kunihiro; Kazuo Ohta
IEICE Transactons, E89-A, 5, 1382-1395, May 2006, Peer-reviwed
Scientific journal, English - Visual Secret Sharing Schemes for Multiple Secret Images Allowing the Rotation of Shares.
Mitsugu Iwamoto; Lei Wang 0031; Kazuki Yoneyama; Noboru Kunihiro; Kazuo Ohta
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, 89-A, 5, 1382-1395, May 2006, Peer-reviwed, In this paper, a method is proposed to construct a visual secret sharing (VSS) scheme for multiple secret images in which each share can be rotated with 180 degrees in decryption. The proposed VSS scheme can encrypt more number of secret images compared with the normal VSS schemes. Furthermore, the proposed technique can be applied to the VSS scheme that allows to turn over some shares in decryption. From the theoretical point of view, it is interesting to note that such VSS schemes cannot be obtained from so-called basis matrices straightforwardly.
Scientific journal, English - Strongly secure ramp secret sharing schemes for general access structures.
Mitsugu Iwamoto; Hirosuke Yamamoto
Information Processing Letters, ELSEVIER SCIENCE BV, 97, 2, 52-57, 2006, Peer-reviwed, Ramp secret sharing (SS) schemes can be classified into strong ramp SS schemes and weak ramp SS schemes. The strong ramp SS schemes do not leak out any part of a secret explicitly even in the case that some information about the secret leaks out from some set of shares, and hence, they are more desirable than the weak ramp SS schemes. In this paper, it is shown that for any feasible general access structure, a strong ramp SS scheme can be constructed from a partially decryptable ramp SS scheme, which can be considered as a kind of SS scheme with plural secrets. As a byproduct, it is pointed out that threshold ramp SS schemes based on Shamir's polynomial interpolation method are not always strong. (c) 2005 Elsevier B.V. All rights reserved.
Scientific journal, English - Quantum secret sharing schemes and reversibility of quantum operations
T Ogawa; A Sasaki; M Iwamoto; H Yamamoto
PHYSICAL REVIEW A, AMERICAN PHYSICAL SOC, 72, 3, 032318, Sep. 2005, Peer-reviwed, Quantum secret sharing schemes encrypting a quantum state into a multipartite entangled state are treated. The lower bound on the dimension of each share given by Gottesman [Phys. Rev. A 61, 042311 (2000)] is revisited based on a relation between the reversibility of quantum operations and the Holevo information. We also propose a threshold ramp quantum secret sharing scheme and evaluate its coding efficiency.
Scientific journal, English - Strongly secure ramp secret sharing schemes.
Mitsugu Iwamoto; Hirosuke Yamamoto
Proceedings of the 2005 IEEE International Symposium on Information Theory(ISIT), IEEE, 1221-1225, 2005, Peer-reviwed, Ramp secret sharing (SS) schemes can be classified into strong ramp SS schemes and weak ramp SS schemes. The strong ramp SS schemes do not leak out any part of a secret explicitly even in the case where some information about the secret leaks from a non-qualified set of shares, and hence, they are more desirable than weak ramp SS schemes. However, it is not known how to construct the strong ramp SS schemes in the case of general access structures. In this paper, it is shown that a strong ramp SS scheme can always be constructed from a SS scheme with plural secrets for any feasible general access structure. As a byproduct, it is pointed out that threshold ramp SS schemes based on Shamir's polynomial interpolation method are not always strong.
International conference proceedings, English - Optimal multiple assignments based on integer programming in secret sharing schemes with general access structures
Mitsugu Iwamoto; Hirosuke Yamamoto; Hirohisa Ogawa
CoRR, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, abs/cs/0506064, 1, 101-112, 2005, Peer-reviwed, It is known that for any general access structure, a secret sharing scheme (SSS) can be constructed from an (m, m)-threshold scheme by using the so-called cumulative map or from a (t, m)-threshold SSS by a modified cumulative map. However, such constructed SSSs are not efficient generally. In this paper, a new method is proposed to construct a SSS from a (t, m)-threshold scheme for any given general access structure. In the proposed method, integer programming is used to derive the optimal (t, m)threshold scheme and the optimal distribution of the shares to minimize the average or maximum size of the distributed shares to participants. From the optimality, it can always attain lower coding rate than the cumulative maps because the cumulative maps cannot attain the optimal distribution in many cases. The same method is also applied to construct SSSs for incomplete access structures and/or ramp access structures.
Scientific journal, English - Quantum Secret Sharing Schemes and Reversibility of Quantum Operations
Tomohiro Ogawa; Akira Sasaki; Mitsugu Iwamoto; Hirosuke Yamamoto
Proceeding of international symposium on information theory and its applications, SITA, 1440-1445, Oct. 2004, Peer-reviwed
International conference proceedings, English - Optimal multiple assignments based on integer programming in secret sharing schemes.
Mitsugu Iwamoto; Hirosuke Yamamoto; Hirohisa Ogawa
Proceedings of the 2004 IEEE International Symposium on Information Theory(ISIT), IEEE, 16-16, 2004, Peer-reviwed, In this paper, it is shown how to derive the optimal secret sharing scheme (SSS) for a given access structure in the multiple assignment schemes.
International conference proceedings, English - A Construction Method of Visual Secret Sharing Schemes for Plural Secret Images.
Mitsugu Iwamoto; Hirosuke Yamamoto
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, 86-A, 10, 2577-2588, Oct. 2003, Peer-reviwed, In this paper; a new method is proposed to construct. a visual secret. sharing scheme with a general access structure for plural secret. images. Although the proposed scheme can be considered as an extension of Droste's method that can encode only black-white images, it can encode plural gray-scale and/or color secret images.
Scientific journal, English - Visual secret sharing schemes for plural secret images
M Iwamoto; H Yamamoto
2003 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY - PROCEEDINGS, IEEE, 283-283, 2003, Peer-reviwed, Visual secret sharing schemes with q plural secret images, for short VSS-q-PI schemes, are studied for general access structures and gray-scale and/or color secret images.
International conference proceedings, English - The Optimal n-out-of-n Visual Secret Sharing Scheme for Gray-Scale Images.
Mitsugu Iwamoto; Hirosuke Yamamoto
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, 85-A, 10, 2238-2247, Oct. 2002, Peer-reviwed, In this paper, a method is proposed to construct an n-out-of-n visual secret sharing scheme for gray-scale images, for short an (n, n)-VSS-GS scheme; which is optimal in the sense of contrast and pixel expansion, i.e., resolution. It is shown that any (n, n)-VSS-GS scheme can be constructed based on the so-called polynomial representation of basis matrices treated in [15], [16]. Furthermore, it is proved that such construction can attain the optimal (n,n)-VSS-GS scheme.
Scientific journal, English - Cache Line Impact on 3D PDE Solvers.
Masaaki Kondo; Mitsugu Iwamoto; Hiroshi Nakamura
High Performance Computing(ISHPC), Springer, 2327, 301-309, 2002, Peer-reviwed, Because performance disparity between processor and main memory is serious, it is necessary to reduce off-chip memory accesses by exploiting temporal locality. Loop tiling is a well-known optimization which enhances data locality. In this paper, we show a new cost model to select the best tile size in 3D partial differential equations. Our cost model carefully takes account of the effect of cache line. We present performance evaluation of our cost models. The evaluation results reveal the superiority of our cost model to other cost models proposed so far. © 2002 Springer Berlin Heidelberg.
International conference proceedings, English - An analytic construction of the visual secret sharing scheme for color images
H Koga; M Iwamoto; H Yamamoto
IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E84A, 1, 262-272, Jan. 2001, Peer-reviwed, This paper proposes a new construction of the visual secret sharing scheme for the (n, n)-threshold access structure applicable to color images. The construction uses matrices with n rows that can be identified with homogeneous polynomials of degree n. It is shown that, if we find a set of homogeneous polynomials of degree n satisfying a certain system of simultaneous partial differential equations, we can construct a visual secret sharing scheme for the (n,n)-threshold access structure by using the matrices corresponding to the homogeneous polynomials. The construction is easily extended to the cases of the (t,n)-threshold access structure and more general access structures.
Scientific journal, English
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Oral presentation, Japanese, 暗号と情報セキュリティシンポジウム (SCIS)
26 Jan. 2023 - 効率的かつ安全な更新処理を備えた結果秘匿可能な検索可能暗号
甘田 拓海; 岩本 貢; 渡邉 洋平
Oral presentation, Japanese, 暗号と情報セキュリティシンポジウム (SCIS)
26 Jan. 2023 - m値n入力関数を計算するprivate PEZプロトコルの初期文字列長の漸近評価
安部 芳紀; 岩本 貢; 太田 和夫
暗号と情報セキュリティシンポジウム (SCIS)
26 Jan. 2023 - Modbus TCP通信のパケット解析と相対エントロピーによる攻撃検知に関する検討
西内 達哉; 藤田 真太郎; 渡邉 洋平; 岩本 貢; 澤田 賢治
Oral presentation, Japanese, 暗号と情報セキュリティシンポジウム (SCIS)
25 Jan. 2023 - 認証信号付きカルマンフィルタに対するレギュレーション性能と攻撃検知率の実験的評価
関根 悠司; 安部 芳紀; 藤田 真太郎; 渡邉 洋平; 澤田 賢治; 岩本 貢
Oral presentation, Japanese, 暗号と情報セキュリティシンポジウム (SCIS)
25 Jan. 2023 - Two Sheriffs Problemの一般化と鍵共有プロトコルへの応用
杉本 航太; 渡邉 洋平; 岩本 貢
Oral presentation, Japanese, 暗号と情報セキュリティシンポジウム (SCIS)
24 Jan. 2023 - 保証金が一定なビットコインベース宝くじプロトコルの拡張
内薗 駿; 中井 雄士; 渡邉 洋平; 岩本 貢
Oral presentation, Japanese, 暗号と情報セキュリティシンポジウム (SCIS)
24 Jan. 2023 - カードを用いた秘匿和集合プロトコル
土井 アナスタシヤ; 小野 知樹; 安部 芳紀; 渡邉 洋平; 岩本 貢
Oral presentation, Japanese, Computer Security Symposium, IPSJ, オンライン, Domestic conference
28 Oct. 2022 - 効率的かつ検索結果秘匿可能な動的検索可能暗号
甘田 拓海; 岩本 貢; 渡邉 洋平
Oral presentation, Japanese, Computer Security Symposium, IPSJ, オンライン, Domestic conference
28 Oct. 2022 - 任意のブール回路に対する秘匿操作を用いたカードベースプロトコル
小野 知樹; 中井 雄士; 渡邉 洋平; 岩本 貢
Oral presentation, Japanese, Computer Security Symposium, IPSJ, オンライン, Domestic conference
28 Oct. 2022 - 攻撃成功確率からみたTwo Sheriffs Problem
杉本 航太; 中井 雄士; 渡邉 洋平; 岩本 貢
Oral presentation, Japanese, Computer Security Symposium, IPSJ, オンライン, Domestic conference
28 Oct. 2022 - 出力埋め込み可能な紛失擬似ランダム関数に基づく多者間秘匿積集合プロトコルの効率化
清水 聖也; 中井 雄士; 渡邉 洋平; 岩本 貢
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 大阪, Domestic conference
20 Jan. 2022 - 一様で閉じたシャッフルの効率的な実装
岩成 慶太; 中井 雄士; 渡邉 洋平; 栃窪 孝也; 岩本 貢
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 大阪, Domestic conference
19 Jan. 2022 - プロービング攻撃による漏洩情報を用いたAES鍵復元アルゴリズムの改良
植村 友紀; 渡邉 洋平; 李 陽; 三浦 典之; 岩本 貢; 崎山 一男; 太田 和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 大阪, Domestic conference
18 Jan. 2022 - 秘匿置換を用いた効率的なn入力多数決カードプロトコル
安部 芳紀; 中井 雄士; 渡邉 洋平; 岩本 貢; 太田 和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 大阪, Domestic conference
18 Jan. 2022 - 効率的な漏洩耐性鍵隔離暗号
淺野 京一; 岩本 貢; 渡邉 洋平
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 大阪, Domestic conference
18 Jan. 2022 - 鍵失効可能な検索可能暗号
平野 貴人; 川合 豊; 小関 義博; 渡邉 洋平; 岩本 貢; 太田 和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 大阪, Domestic conference
18 Jan. 2022 - Key-Insulated Public-Key Encryption with Secret-Key Leakage Resilience
淺野京一; 渡邉 洋平; 岩本貢
Oral presentation, Japanese, Computer Security Symposium, IPSJ, オンライン, Domestic conference
28 Oct. 2021 - Card-based Cryptographic Protocols for Private Set Intersection
土井 アナスタシヤ; 中井 雄士; 品川 和雅; 渡邉 洋平; 岩本貢
Oral presentation, Japanese, Computer Security Symposium, IPSJ, オンライン, Domestic conference
26 Oct. 2021 - 紛失通信ベース三者間秘匿積集合プロトコルにおけるラウンド数の削減
清水 聖也; 安部 芳紀; 中井 雄士; 品川 和雅; 渡邉 洋平; 岩本 貢
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, virtual, Domestic conference
22 Jan. 2021 - 検索可能暗号の鍵更新について
平野 貴人; 川合 豊; 小関 義博; 渡邉 洋平; 岩本 貢; 太田 和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, virtual, Domestic conference
21 Jan. 2021 - AES鍵スケジュールからの固定ビット数漏洩を用いた鍵復元アルゴリズムの性能評価
植村 友紀; 渡邉 洋平; 李 陽; 三浦 典之; 岩本 貢; 崎山 一男; 太田 和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, virtual, Domestic conference
20 Jan. 2021 - 秘匿置換を用いたカードベースしきい値関数プロトコル
中井 雄士; 徳重 佑樹; 岩本 貢; 太田 和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, virtual, Domestic conference
20 Jan. 2021 - 時間ドロボー問題に対する健全性誤りのない物理的ゼロ知識証明
初貝 恭祐; 安部 芳紀; 中井 雄士; 品川 和雅; 渡邉 洋平; 岩本 貢
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, virtual, Domestic conference
20 Jan. 2021 - 視覚復号型秘密分散法における任意の改ざんを検知する手法
根岸 奎人; 渡邉 洋平; 岩本 貢
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, virtual, Domestic conference
20 Jan. 2021 - より少ない漏洩の下で安全な動的検索可能暗号への変換手法
渡邉 洋平; 大原 一真; 岩本 貢; 太田 和夫
Public symposium, Japanese, Computer Security Symposium, ISEC, IEICE, 新潟, Domestic conference
24 Oct. 2020 - 任意の始集合を持つ関数を計算する private PEZ プロトコル
安部芳紀; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 高知市, Domestic conference
30 Jan. 2020 - 鍵のランダムな漏洩に対するAES鍵スケジュール復元アルゴリズム
植村友紀; 李陽; 三浦典之; 岩本貢; 崎山一男; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 高知市, Domestic conference
29 Jan. 2020 - 気泡検出器を用いたゼロ知識非破壊検査
品川和雅; 三浦典之; 岩本貢; 崎山一男; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 高知市, Domestic conference
29 Jan. 2020 - (強)フォワード安全な動的検索可能暗号の効率的な構成
渡邉洋平; 大原一真; 岩本貢; 太田和夫
Oral presentation, Japanese, コンピュータセキュリティシンポジウム, 情報処理学会, 長崎, Domestic conference
23 Oct. 2019 - How to Improve the Private PEZ Protocol for General Functions
安部芳紀; 岩本貢; 太田和夫
Oral presentation, Japanese, Computer Security Symposium, IPSJ, 長崎, Domestic conference
21 Oct. 2019 - How to Improve the Private PEZ Protocol for General Functions
Yoshiki Abe; Mitsugu Iwamoto; Kazuo Ohta
Poster presentation, English, International Workshop on Information Security (IWSEC), International conference
28 Aug. 2019 - 初期文字列が 29 文字の 4 入力多数決 Private PEZ プロトコル
安部 芳紀; 山本 翔太; 岩本 貢; 太田 和夫
Oral presentation, Japanese, Technical meeting of IEICE (ISEC)
08 Mar. 2019 - 秘密計算の安全性～プライバシーを保ちつつどこまで計算できるか
岩本貢
Invited oral presentation, Japanese, 第8回バイオメトリクスと認識・認証シンポジウム, Invited, 電子情報通信学会 バイオメトリクス研究専門委員会 (BioX), 東京都千代田区, http://www.ieice.org/~biox/sbra2018/, Domestic conference
20 Nov. 2018 - 現実的な結託者のもとで最もシェア長の短いロバスト秘密分散法
渡邉洋平; 大原一真; 岩本貢; 太田和夫
Oral presentation, Japanese, Technical meeting of IEICE (ISEC)
25 Jul. 2018 - マルチユーザで利用可能な共通鍵型秘匿検索に向けて
早坂 健一郎; 川合 豊; 小関 義博; 平野 貴人; 岩本 貢; 太田 和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 新潟, Domestic conference
25 Jan. 2018 - ダミーエントリの作成方法に着目した共通鍵検索可能暗号CGKO方式の改良
野島 拓也; 渡邉 洋平; 岩本 貢; 太田 和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 新潟, Domestic conference
25 Jan. 2018 - PUF応用に向けた新たな物理仮定と端末認証方式への応用
駒野雄一; 岩本 貢; 太田和夫; 崎山 一男
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 新潟, Domestic conference
24 Jan. 2018 - ロバスト秘密分散法CFOR方式における精密な安全性解析
鈴木慎之介; 渡邉洋平; 岩本 貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 新潟, Domestic conference
24 Jan. 2018 - 3枚のカードで実現可能な3入力多数決プロトコル
黒木慶久; 古賀優太; 渡邉洋平; 岩本 貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 新潟, Domestic conference
24 Jan. 2018 - カードを用いた複数人でのマッチングプロトコル
古賀優太; 鈴木 慎之介; 渡邉 洋平; 岩本 貢; 太田 和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 新潟, Domestic conference
24 Jan. 2018 - 情報理論的安全性 〜さまざまな視点から〜
岩本貢
Oral presentation, Japanese, 誤り訂正符号のワークショップ, Invited, 誤り訂正符号のワークショップ 実行委員会, 山口県, http://manau.jp/WS/ECCWS/index2017.html, Domestic conference
06 Sep. 2017 - PUF based Device Authentication without Error Correction
駒野 雄一; 岩本 貢; 太田 和夫
Japanese, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 電子情報通信学会, http://id.ndl.go.jp/bib/028443592
14 Jul. 2017
14 Jul. 2017- 14 Jul. 2017 - 誤り補正を不要とするPUF ベース端末認証方式
駒野雄一; 岩本貢; 太田和夫
Oral presentation, Japanese, Technical meeting of IEICE (ISEC)
14 Jul. 2017 - Secret sharing schemes under guessing secrecy
Mitsugu Iwamoto
Invited oral presentation, English, Cryptographic Technologies for Securing Network Storage and Their Mathematical Modeling, Invited, Math for Industry, Kyushu University, Fukuoka, Japan, http://www.imi.kyushu-u.ac.jp/eng/events/view/1240, International conference
12 Jun. 2017 - 検索可能暗号における最小漏洩情報に関する考察
中井雄士; 野島拓也; 岩本貢; 太田和夫
Oral presentation, Japanese, 電子情報通信学会 情報理論研究会 (IT/ISEC/WBS)
10 Mar. 2017 - A Note on Acceptable Information Leakage of Searchable Symmetric Encryption
中井 雄士; 野島 拓也; 岩本 貢; 太田 和夫
Japanese, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 電子情報通信学会, http://id.ndl.go.jp/bib/028102830
09 Mar. 2017
09 Mar. 2017- 09 Mar. 2017 - A Note on Acceptable Information Leakage of Searchable Symmetric Encryption
中井 雄士; 野島 拓也; 岩本 貢; 太田 和夫
Japanese, 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 電子情報通信学会, http://id.ndl.go.jp/bib/028101582
09 Mar. 2017
09 Mar. 2017- 09 Mar. 2017 - 秘密分散型放送暗号
岩本貢; 渡邉 洋平
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 沖縄, Domestic conference
27 Jan. 2017 - マルチパーティ計算に関する安全性概念の定式化について
岩本貢
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 沖縄, Domestic conference
25 Jan. 2017 - リクエストベース比較可能暗号におけるシミュレー ションベースの安全性
平野貴人; 小関義博; 川合豊; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 沖縄, Domestic conference
24 Jan. 2017 - 電子決済方式MicroMintの潜在的な偽造脅威に対する安全性評価
鴨志田優一; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 沖縄, Domestic conference
24 Jan. 2017 - 秘匿操作を用いた効率的なカードベース論理演算プロトコル
城内聡志; 中井雄士; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 沖縄, Domestic conference
24 Jan. 2017 - カードを用いた複数人での金持ち比べプロトコル
徳重佑樹; 中井雄士; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 沖縄, Domestic conference
24 Jan. 2017 - Steganalysis of Bit Replacement Steganography for a Proactive Secret Image Sharing
A. Espejel-Trujillo; M. Iwamoto
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 沖縄, Domestic conference
24 Jan. 2017 - 最悪推測秘匿性を満たす秘密分散法に関する基本的性質
岩本貢; 四方順司
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 沖縄, Domestic conference
24 Jan. 2017 - 検索クエリからの漏洩情報を削減 した効率的な共通鍵型検索可能暗号
早坂健一郎; 川合 豊; 小関 義博; 平野 貴人; 岩本貢; 太田 和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 沖縄, Domestic conference
24 Jan. 2017 - 複数の暗号化索引を持つ共通鍵ベース秘匿検索の効率的なトラップドア生成
平野貴人; 岩本貢; 太田和夫
Public symposium, Japanese, Computer Security Symposium, CSEC, IPSJ, 秋田, Domestic conference
12 Oct. 2016 - 長期間にわたって安全な地域医療連携システムの構築 を目指して
小美濃つかさ; 駒野雄一; 岩本貢; 太田和夫
Oral presentation, Japanese, 第 36 回医療情報学連合大会
21 Sep. 2016 - Deep Learning を用いたRSAに対する単純電磁波解析
八代理紗; 藤井達哉; 岩本貢; 崎山一男
Oral presentation, Japanese, 電子情報通信学会ソサイエティ大会
21 Sep. 2016 - A-7-13 Security Evaluation of Double Arbiter PUF Using Deep Learning
Yashiro Risa; Machida Takanori; Iwamoto Mitsugu; Sakiyama Kazuo
Japanese, Proceedings of the IEICE Engineering Sciences Society/NOLTA Society Conference, The Institute of Electronics, Information and Communication Engineers
01 Mar. 2016
01 Mar. 2016- 01 Mar. 2016 - Deep Learning を用いたDouble Arbiter PUF の安全性評価
八代理紗; 町田卓謙; 岩本貢; 崎山一男
Oral presentation, Japanese, 電子情報通信学会総合大会
Mar. 2016 - カード操作の分類とカードベース暗号プロトコル
中井雄士; 三澤裕人; 徳重佑樹; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 熊本, Domestic conference
Jan. 2016 - 人間向け暗号/認証プロトコルの統一的安全性評価
三澤裕人; 徳重佑樹; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 熊本, Domestic conference
Jan. 2016 - Joux-Lucks のマルチコリジョン探索アルゴリズムのMicroMint への応用
鴨志田優一; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 熊本, Domestic conference
Jan. 2016 - Proactive Secret Image Sharing with Quality and Payload Trade-off in Stego-images
A. E. Trujillo; M. Iwamoto
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 熊本, Domestic conference
Jan. 2016 - 共通鍵暗号型の秘匿部分一致検索（その2）
早坂健一郎; 川合豊; 平野貴人; 太田和夫; 岩本貢
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 熊本, Domestic conference
Jan. 2016 - 共通鍵暗号型の秘匿部分一致検索（その１）
平野貴人; 川合豊; 太田和夫; 岩本貢
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 熊本, Domestic conference
Jan. 2016 - グループ認証付鍵交換プロトコルのweak-SK-secure 性の形式検証
徳重佑樹; 花谷嘉一; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 熊本, Domestic conference
Jan. 2016 - Impact of Code Book on Security of Coded Sign
Yuto Misawa; Yuuki Tokushige; Mitsugu Iwamoto; Kazuo Ohta
Public symposium, Japanese, Computer Security Symposium, CSEC, IPSJ, 長崎, Domestic conference
23 Oct. 2015 - 正規言語を用いた鍵更新可能暗号の安全性解析
大宮翔児; 徳重佑樹; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2015 - 推測成功確率に基づいた安全性基準をみたす秘密分散法
岩本貢; 四方順司
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2015 - 推測確率に基づいた安全性基準をみたす暗号化方式の構成法
岩本貢; 四方順司
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2015 - あるCKA2 安全な検索可能暗号方式のトラップドアサイズを削減するための安全な分割手法
平野貴人; 川合豊; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2015 - Joux-Lucks の3-collisions 探索アルゴリズムに対する改良および計算量の詳細な検討
鴨志田優一; 徳重佑樹; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2015 - Corrupt 耐性を持つセッションキー安全な秘密鍵失効機能付きSecret Handshake 方式
土屋喬文; 花谷嘉一; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2015 - カードを用いた効率的な金持ち比べプロトコル
中井雄士; 徳重佑樹; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2015 - カードベース暗号プロトコルにおける安全な選択処理
徳重佑樹; 中井雄士; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2015 - 簡易なブロックサインに対する暗号理論的安全性解析
三澤裕人; 徳重佑樹; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2015 - 秘密分散法と視覚復号型秘密分散法 - 共通点と相違点 —共通点と相違点
Mitsugu Iwamoto
Public discourse, Japanese, EMM研究会, Invited, 電子情報通信学会EMM研究会, 東京理科大学葛飾キャンパス
16 May 2014 - ハッシュ関数に対する制限付き誕生日識別攻撃−誕生日下界を上回る衝突攻撃の識別攻撃に対する有効性
岩本貢; 佐々木悠
Invited oral presentation, Japanese, 電子情報通信学会 情報セキュリティ研究会, Invited, 電子情報通信学会情報セキュリティ専門委員会, 機械振興会館, Domestic conference
09 May 2014 - 最小エントロピーに基づく秘密分散法
岩本貢; 四方順司
Invited oral presentation, Japanese, 暗号理論ワークショップ, Invited, 東京大学柏キャンパス, Domestic conference
Mar. 2014 - Practical DFA Strategy for AES Under Limited-access Conditions
Kazuo Sakiyama; Yang Li; Shigeto Gomisawa; Yu-ichiHayashi; Mitsugu Iwamoto; Naofumi Homma; Takafumi Aoki; Kazuo Ohta
English, 情報処理学会論文誌, http://id.nii.ac.jp/1001/00098502/, Secret data in embedded devices can be revealed by injecting computational faults using the fault analysis attacks. The fault analysis researches on a cryptographic implementation by far first assumed a certain fault model, and then discussed the key recovery method under some assumptions. We note that a new remote-fault injection method has emerged, which is threatening in practice. Due to its limited accessibility to cryptographic devices, the remote-fault injection, however, can only inject uncertain faults. In this surroundings, this paper gives a general strategy of the remote-fault attack on the AES block cipher with a data set of faulty ciphertexts generated by uncertain faults. Our method effectively utilizes all the information from various kinds of faults, which is more realistic than previous researches. As a result, we show that it can provide a decent success probability of key identification even when only a few intended faults are available among 32 millions fault injections.------------------------------This is a preprint of an article intended for publication Journal ofInformation Processing(JIP). This preprint should not be cited. Thisarticle should be cited as: Journal of Information Processing Vol.22(2014) No.2 (online)DOI http://dx.doi.org/10.2197/ipsjjip.22.142------------------------------Secret data in embedded devices can be revealed by injecting computational faults using the fault analysis attacks. The fault analysis researches on a cryptographic implementation by far first assumed a certain fault model, and then discussed the key recovery method under some assumptions. We note that a new remote-fault injection method has emerged, which is threatening in practice. Due to its limited accessibility to cryptographic devices, the remote-fault injection, however, can only inject uncertain faults. In this surroundings, this paper gives a general strategy of the remote-fault attack on the AES block cipher with a data set of faulty ciphertexts generated by uncertain faults. Our method effectively utilizes all the information from various kinds of faults, which is more realistic than previous researches. As a result, we show that it can provide a decent success probability of key identification even when only a few intended faults are available among 32 millions fault injections.------------------------------This is a preprint of an article intended for publication Journal ofInformation Processing(JIP). This preprint should not be cited. Thisarticle should be cited as: Journal of Information Processing Vol.22(2014) No.2 (online)DOI http://dx.doi.org/10.2197/ipsjjip.22.142------------------------------
15 Feb. 2014
15 Feb. 2014- 15 Feb. 2014 - FPGA 実装されたArbiter-based PUF のユニーク性向上に向けた実装法の検討
町田卓謙; 山本大; 岩本貢; 崎山一男
Public symposium, Japanese, Hot Channel Workshop, Domestic conference
2014 - Cheating on Visual Secret Sharing Schemes in Practical Setting
P. Lumyong; M. Iwamoto; K. Ohta
Public symposium, English, Symposium on Cryptography and Information Security, ISEC, IEICE, 鹿児島, Domestic conference
Jan. 2014 - “Optimal Non-Perfectly Secure Client-Server Communications in a Symmetric Key Setting,
M. Iwamoto; T. Omino; Y. Komano; K. Ohta
Public symposium, English, Symposium on Cryptography and Information Security, ISEC, IEICE, 鹿児島, Domestic conference
Jan. 2014 - 情報理論的に安全なクライアント・サーバ暗号通信方式の応用に関する考察
小美濃つかさ; 岩本貢; 駒野雄一; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 鹿児島, Domestic conference
Jan. 2014 - FPGA 実装されたArbiter PUF のユニーク性向上に向けた一考察
町田卓謙; 山本大; 岩本貢; 崎山一男
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 鹿児島, Domestic conference
Jan. 2014 - 自動タイブレークの仕組みを持つ第M+1 価格暗号オークション方式
西出隆志; 岩本貢; 岩崎敦; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 鹿児島, Domestic conference
Jan. 2014 - 同時実行攻撃に耐性を持つシンプルなSecret Handshake
土屋喬文; 徳重佑樹; 坂井祐介; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 鹿児島, Domestic conference
Jan. 2014 - Improved Rebound Attack 手順の自動探索手法の提案と評価
徳重佑樹; 佐々木悠; 王磊; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 鹿児島, Domestic conference
Jan. 2014 - Information Theoretic Cryptography based on Conditional Rényi Entropies
Mitsugu Iwamoto; Junji Shikata
Invited oral presentation, Japanese, 暗号理論ワークショップ, Invited, 東京工業大学大岡山キャンパス, Domestic conference
Feb. 2013 - Security notions of visual secret sharing schemes
M. Iwamoto
Invited oral presentation, English, International Workshop on Advanced Image Technology, Invited, Nagoya, International conference
06 Jan. 2013 - Information Theoretic Analysis of a t-resilient First-Price Auction Protocol
M. Iwamoto; K. Ohara; Y. Sakai; K. Ohta
Public symposium, English, Symposium on Cryptography and Information Security, ISEC, IEICE, 京都, Domestic conference
Jan. 2013 - CC-EMA とCEMA の攻撃性能の比較
中曽根俊貴; 李陽; 佐々木悠; 岩本貢; 太田和夫; 崎山一男
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 京都, Domestic conference
Jan. 2013 - レスポンス数の向上手法を適用したラッチPUFのASIC 実装評価
山本大; 崎山一男; 岩本貢; 太田和夫; 武仲正彦; 伊藤孝一; 鳥居直哉
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 京都, Domestic conference
Jan. 2013 - PUF 出力の一部を用いるパターン照合鍵生成システムの安全性
駒野雄一; 太田和夫; 崎山一男; 岩本貢
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 京都, Domestic conference
Jan. 2013 - Revisiting Conditional Renyi Entropy and its Application to Encryption: Part I ―Properties of Conditional Renyi Entropy
M. Iwamoto; J. Shikata
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 京都, Domestic conference
Jan. 2013 - PUF を用いる鍵生成方法とその安全性
駒野雄一; 太田和夫; 崎山一男; 岩本貢
Public symposium, Japanese, Hot Channel Workshop, Domestic conference
2013 - FPGA 上のArbiter PUF に対する機械学習攻撃の新たなモデル作成に向けて
町田卓謙; 中曽根俊貴; 岩本貢; 崎山一男
Public symposium, Japanese, Hot Channel Workshop, Domestic conference
2013 - Revisiting Conditional Renyi Entropy and its Application to Encryption: Part II ―Fano’s Inequality and Shannon's Bound
J. Shikata; M. Iwamoto
Public symposium, English, Symposium on Cryptography and Information Security, ISEC, IEICE, 京都, Domestic conference
Jan. 2013 - 巡回シフトを用いたPUF に基づくパターン照合鍵生成システムの実装評価
岩井祐樹; 福島崇文; 森山大輔; 松尾真一郎; 駒野雄一; 岩本貢; 太田和夫; 崎山一男
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 京都, Domestic conference
Jan. 2013 - A-7-9 IMPROVED PATTERN MATCHING KEY GENERATION USING PUF
Komano Yuichi; Ohta Kazuo; Sakiyama Kazuo; Iwamoto Mitsugu
Japanese, Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers
06 Mar. 2012
06 Mar. 2012- 06 Mar. 2012 - Entropic Security for Predicates and Functions
M.Iwamoto; A.Russell
Invited oral presentation, Japanese, 統計数理研究所共同利用研究集会（エルゴード理論，情報理論，計算機科学とその周辺, Invited, 東京工業大学大岡山キャンパス, http://ura3.c.ism.ac.jp/stats/msg01569.html, Domestic conference
05 Mar. 2012 - しきい値法の一般化とその構成法
岩本貢
Oral presentation, Japanese, 電子情報通信学会総合大会
Mar. 2012 - PUF を用いるパターン照合鍵生成方法の改良
駒野雄一; 太田和夫; 崎山一男; 岩本貢
Oral presentation, Japanese, 電子情報通信学会総合大会
Mar. 2012 - 関数に対するentropic securityの安全性
M.Iwamoto; A.Russell
Invited oral presentation, Japanese, CompView暗号理論ワークショップ, Invited, 東工大GCOE「計算世界観の深化と展開」, 東京工業大学大岡山キャンパス, Domestic conference
Feb. 2012 - 二つの情報理論的安全なオークションプロトコル
大原一真; 坂井祐介; 岩本貢; 太田和夫
Invited oral presentation, Japanese, CompView暗号理論ワークショップ, Invited, 東工大GCOE「計算世界観の深化と展開」, 東工大蔵前会館, Domestic conference
Feb. 2012 - PUF を用いる証明可能安全なパターン照合鍵生成方法
駒野雄一; 太田和夫; 崎山一男; 岩本貢
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 金沢, Domestic conference
Jan. 2012 - 情報理論的に安全な First-Price オークションプロトコル
大原一真; 坂井祐介; 岩本貢; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 金沢, Domestic conference
Jan. 2012 - Uniqueness Enhancement of PUF Responses based on the locations of random outputting latches PUF Responses Based on the Locations of Random Outputting RS Latches
山本大; 崎山一男; 岩本貢; 太田和夫; 落合隆夫; 武仲正彦; 伊藤孝一
Invited oral presentation, Japanese, 電子情報通信学会 情報セキュリティ研究会, Invited, 電子情報通信学会情報セキュリティ専門委員会, 機械振興会館
Dec. 2011 - A Coding Theorem for Cheating-Detectable (2,2)-Threshold Schemes
岩本貢; 太田和夫
Oral presentation, Japanese, Technical meeting of IEICE (IT)
May 2011 - Trivium のセットアップタイム違反に基づく新しい故 障差分解析
李奇; 五味澤重友; 岩本貢; 太田和夫; 崎山一男
Oral presentation, Japanese, Technical meeting of IEICE (ISEC)
Mar. 2011 - New Differential Fault Analysis on Trivium Based on Setup-Time Violations
LI Qi; GOMISAWA Shigeto; IWAMOTO Mitsugu; OHTA Kazuo; SAKIYAMA Kazuo
English, IEICE technical report, The Institute of Electronics, Information and Communication Engineers, http://id.ndl.go.jp/bib/11048486, This paper presents new differential fault analysis (DFA) on a stream cipher Trivium based on setup-time violations. Trivium is a hardware-oriented synchronous stream cipher, designed by De Canniere and Preneel in 2005. In 2008, Hojsik and Rudolf first presented differential fault analysis of Trivium and proposed two types of DFA on Trivium. Setup-time violations are common fault injection methods for hardware implementations. We show that we have succeeded in injecting faults into FPGA on SASEBO-GII in which Trivium is implemented, and in obtaining 147 out of 288 secret bits with 93 fault injections at different rounds. According to our experiments, we found it is difficult to inject 1-bit errors into random positions of the registers of Trivium at a specific round that was proposed in the previous work of Hojsik and Rudolf.
24 Feb. 2011
24 Feb. 2011- 24 Feb. 2011 - New Differential Fault Analysis on Trivium Based on Setup-Time Violations
LI Qi; GOMISAWA Shigeto; IWAMOTO Mitsugu; OHTA Kazuo; SAKIYAMA Kazuo
English, IEICE technical report, The Institute of Electronics, Information and Communication Engineers, http://id.ndl.go.jp/bib/11047284, This paper presents new differential fault analysis (DFA) on a stream cipher Trivium based on setup-time violations. Trivium is a hardware-oriented synchronous stream cipher, designed by De Canniere and Preneel in 2005. In 2008, Hojsik and Rudolf first presented differential fault analysis of Trivium and proposed two types of DFA on Trivium. Setup-time violations are common fault injection methods for hardware implementations. We show that we have succeeded in injecting faults into FPGA on SASEBO-GII in which Trivium is implemented, and in obtaining 147 out of 288 secret bits with 93 fault injections at different rounds. According to our experiments, we found it is difficult to inject 1-bit errors into random positions of the registers of Trivium at a specific round that was proposed in the previous work of Hojsik and Rudolf.
24 Feb. 2011
24 Feb. 2011- 24 Feb. 2011 - Threshold based visual cryptography: A tutorial review
Mariko Nakano; Enrique Escamilla; Héctor Pérez; Mitsugu Iwamoto
Spanish, Castilian, Informacion Tecnologica, In this paper, a review for threshold-based visual cryptography (VC), a visual representation of the secret sharing scheme is presented. The VC has potential applications in the electronic banking system, as well as in personal identification systems. En la VC a binary image such as letters, logotypes or halftone images are shared among a group of participants using a set of images, so called shares. Until now several VC schemes, such as threshold-based VC, the general access VC and the extended VC, have been proposed. The conditions that must be satisfied for a correct recovery of the secret message, as well as the most relevant security issues of this scheme are also analyzed.
2011
2011 2011 - Joux-Lucks の 3-collisions 探索アルゴリズムに関する計算量 の詳細な検討
名渕大樹; 岩本貢; 崎山一男; 太田 和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2011 - FDH 署名の安全性証明の再考
坂井 祐介; 岩本 貢; 駒野 雄一; 太田 和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2011 - ラッチの乱数出力位置を利用した PUF による ID 生成/認証システムの信頼性向上手法
山本大; 崎山一男; 岩本貢; 太田和夫; 落合 隆夫; 武仲 正彦; 伊藤 孝一
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2011 - 電磁波解析における局所性と放射磁界方向について
落合隆夫; 山本大; 伊藤 孝一; 武仲正彦; 鳥居直哉; 内田大輔; 永井利明; 若菜伸一; 岩本貢; 太田和夫; 崎山一男; 山 一男
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 小倉, Domestic conference
Jan. 2011 - 情報理論的に安全な暗号化のための安全性概念
Mitsugu Iwamoto; Kazuo Ohta
Public symposium, Japanese, Symposium on Information Theory and Its Applications (SITA), 情報理論とその応用学会, Domestic conference
Dec. 2010 - A general construction method of visual secret sharing scheme with share rotations
IWMAOTO Mitsugu; LI Yang; SAKIYAMA Kazuo; OHTA Kazuo
English, Technical report of IEICE. ISEC, The Institute of Electronics, Information and Communication Engineers, http://id.ndl.go.jp/bib/10846085, In this paper, we discuss a visual secret sharing scheme with multiple secret images including share rotation operations with arbitrary degrees, as an extension of the S-extended (n,n) visual secret sharing scheme proposed by Droste. As a result, it is pointed out that the proposed visual secret sharing scheme can be naturally derived from the S-extended (n,n) visual secret sharing scheme.
03 Sep. 2010
03 Sep. 2010- 03 Sep. 2010 - A general construction method of visual secret sharing schemes with share rotations
M. Iwamoto; Y. Li; K. Sakiyama; K. Ohta
Oral presentation, English, Technical meeting of IEICE (ISEC)
May 2010 - PUF-HB認証プロトコルに対する能動的な攻撃
長井大地; 塙知剛; 岩本貢; 崎山一男; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 香川, Domestic conference
Jan. 2010 - A Novel Construction Method for Visual Secret Sharing Schemes Allowing Rotation of Shares
Yang Li; Mitsugu Iwamoto; Kazuo Ohta; Kazuo Sakiyama
Oral presentation, Japanese, Technical meeting of IEICE (ISEC)
May 2009 - A Coding Theorem for Cheating-Detectable (2,2)-Threshold Schemes
Hiroki Koga; Hirosuke Yamamoto
Oral presentation, Japanese, Technical meeting of IEICE (IT)
Mar. 2009 - Weakly Secure Visual Secret Sharing Schemes
Mitsugu Iwamoto
Public symposium, English, Symposium on Cryptography and Information Security, ISEC, IEICE, 大津, Domestic conference
Jan. 2009 - Secret Sharing Schemes with Asymptotically Almost Sure Cheating Detection
Mitsugu Iwamoto; Hirosuke Yamamoto; Hiroki Koga
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 大津, Domestic conference
Jan. 2009 - Secret Sharing Schemes with Asymptotically Almost Sure Cheating Detection
Mitsugu Iwamoto; Hirosuke Yamamoto
Public symposium, Japanese, Symposium on Information Theory and Its Applications (SITA), 情報理論とその応用学会, Domestic conference
Oct. 2008 - A Dynamic Key Predistribution Scheme Taking Users' Behavior into Consideration
Masyuki Taguchi; Mitsugu Iwamoto
Public symposium, Japanese, Symposium on Information Theory and Its Applications (SITA), 情報理論とその応用学会, Domestic conference
Dec. 2006 - Coding theorems for secret sharing schemes
Mitsugu Iwamoto
Invited oral presentation, Japanese, 電子情報通信学会ソサイエティ大会, Invited, IEICE, 金沢大学
Sep. 2006 - Visual Secret Sharing Schemes for Plural Secret Images with General Access Structures Allowing the Rotation of Shares
IWAMOTO Mitsugu; WANG Lei; YONEYAMA Kazuki; KUNIHIRO Noboru; OHTA Kazuo
Japanese, 情報理論とその応用シンポジウム予稿集 = The proceedings of the Symposium on Information Theory and Its Applications
20 Nov. 2005
20 Nov. 2005- 20 Nov. 2005 - 回転を許す一般アクセス構造に対して複数の画像を隠す視覚復号型秘密分散法
Mitsugu Iwamoto; Lei Wang; Kazuki Yoneyama; Noboru Kunihiro; Kazuo Ohta
Public symposium, Japanese, Symposium on Information Theory and Its Applications (SITA), 情報理論とその応用学会, Domestic conference
Nov. 2005 - 画像の回転に関して複数の画像が復号可能な視覚復号型秘密分散法
清田耕一郎; 王磊; 岩本貢; 米山一樹; 國廣昇; 太田和夫
Public symposium, Japanese, Symposium on Cryptography and Information Security, ISEC, IEICE, 舞子, Domestic conference
Jan. 2005 - Strongly Secure Ramp Secret Sharing Schemes for General Access Structures
IWAMOTO Mitsugu; YAMAMOTO Hirosuke
Japanese, 情報理論とその応用シンポジウム予稿集 = The proceedings of the Symposium on Information Theory and Its Applications
14 Dec. 2004
14 Dec. 2004- 14 Dec. 2004 - 強い秘密保護特性をもつランプ型秘密分散法
Mitsugu Iwamoto; Hirosuke Yamamoto
Public symposium, Japanese, Symposium on Information Theory and Its Applications (SITA), 情報理論とその応用学会, Domestic conference
Dec. 2004 - 量子秘密分散法の符号化効率評価と構成法
Tomohiro Ogawa; Akira Sasaki; Mitsugu Iwamoto; Hirosuke Yamamoto
Public symposium, Japanese, Symposium on Information Theory and Its Applications (SITA), 情報理論とその応用学会, Domestic conference
Dec. 2003 - A General Construction Method of Secret Sharing Schemes Based on (k, n)-threshold Schemes and Integer Programming
IWAMOTO Mitsugu; YAMAMOTO Hirosuke; OGAWA Hirohisa
Japanese, Technical report of IEICE. ISEC, The Institute of Electronics, Information and Communication Engineers, http://id.ndl.go.jp/bib/6619768, It is known that secret sharing schemes (SSSs) for general access structures can be constructed from the (k,n)-threshold schemes by using the so-called cumulative map. However, the original cumulative map can treat only the case of k = n. Furthermore, a known modified cumulative map that can deal with general (k,n)-threshold schemes is not always more efficient than the cumulative map. In this paper, we propose a new method to construct the SSSs for general access structures from the (k,n)-threshold schemes. In the proposed method, integer programming is used to derive the optimal distribution of shares to each participant, and as results, it can attain lower coding rate than the cumulative maps generally.
14 May 2003
14 May 2003- 14 May 2003 - (k,n)しきい値法と整数計画法による秘密分散法の一般的構成法（共著）
岩本貢; 山本博資; 小川博久
Oral presentation, Japanese, Technical meeting of IEICE (ISEC)
May 2003 - The Security Condition of Visual Secret Sharing Schemes for Plural Images
IWAMOTO Mitsugu; YAMAMOTO Hirosuke
Japanese, Technical report of IEICE. SST, The Institute of Electronics, Information and Communication Engineers, http://id.ndl.go.jp/bib/6145104, The security condition of visual secret sharing schemes for q plural images (VSSS-q-PI) is considered in [9]. However, the condition is insufficient because some informations of the other secret images leak out from decrypted images even if the definition of VSSS-q-PI shown in [9] is satisfied. Hence, we give the new perfect definition of the security condition, and we propose a construction method which satisfies the new definition of the VSSS-q-PI. The proposed method is an extension of the known methods shown in [3] [8] [9].
19 Mar. 2002
19 Mar. 2002- 19 Mar. 2002 - 複数の秘密画像をもつ視覚復号型秘密分散法の安全性条件
岩本貢; 山本博資
Oral presentation, Japanese, 電子情報通信学会 情報セキュリティ研究会 (ISEC)
Mar. 2002 - 一般アクセス構造に対する非理想的ランプ型秘密分散法
Mitsugu Iwamoto; Hirosuke Yamamoto
Public symposium, Japanese, Symposium on Information Theory and Its Applications (SITA), 情報理論とその応用学会, Domestic conference
2002 - A visual secret sharing scheme for plural images
IWAMOTO Mitsugu; YAMAMOTO Hirosuke
Japanese, 情報理論とその応用シンポジウム予稿集 = The proceedings of the Symposium on Information Theory and Its Applications
04 Dec. 2001
04 Dec. 2001- 04 Dec. 2001 - 複数のカラー画像を秘密画像とする視覚復号型秘密分散法
Mitsugu Iwamoto; Hirosuke Yamamoto
Public symposium, Japanese, Symposium on Information Theory and Its Applications (SITA), 情報理論とその応用学会, Domestic conference
Dec. 2001 - 濃淡画像に対する最適な(n,n)視覚復号型秘密分散法
Mitsugu Iwamoto; Hirosuke Yamamoto
Public symposium, Japanese, Computer Security Symposium, CSEC, IPSJ, 盛岡, Domestic conference
Oct. 2001 - キャッシュラインを考慮した３次元PDE Solverの最適化手法（共著）
近藤正章; 岩本貢; 中村宏
Oral presentation, Japanese, 情報処理学会研究報告
Mar. 2001 - NAS PB CG, FTにおけるSCIMAの性能評価(共著)
岩本貢; 渡辺亮介; 近藤正章; 中村宏; 朴泰祐
Oral presentation, Japanese, 情報処理学会研究報告
Oct. 2000 - An analytic construction of the visual secret sharing scheme for color images
Hiroki Koga; Mitsugu Iwamoto; Hirosuke Yamamaoto
Public symposium, English, Symposium on Cryptography and Information Security, ISEC, IEICE, 沖縄, Domestic conference
Jan. 2000 - カラー画像に対する一般のアクセス構造をもつ視覚復号型秘密分散法の一構成法
Mitsugu Iwamoto; Hiroki Koga; Hirosuke Yamamoto
Public symposium, Japanese, Symposium on Information Theory and Its Applications (SITA), 情報理論とその応用学会, 越後湯沢, Domestic conference
Nov. 1999
Affiliated academic society
Research Themes
- Trustworthy IoTシステム設計基盤の構築
岩本貢
科学技術振興機構, 戦略的な研究開発の推進 戦略的創造研究推進事業 CREST, 東京工業大学, Coinvestigator, 近年、IC製造工程に外部企業が関わることで、IC設計技術(IP)盗用や非正規品流通の問題が深刻化しています。本研究は、ICサプライチェーン全体の安全性要件を抽出・モデル化し、その要件を満たす新たな仕組みを高機能暗号を基盤として構築することで、ICのIP保護と真正性確認の一括した実現を目指します。この仕組みをIC設計時にby-Designで設計情報に組み込むための設計手法とその設計環境を開発します。, JPMJCR23M2
2023 - 2028 - 情報・計算・暗号の融合によるセキュリティ定量化基盤の構築
安永 憲司,渡辺峻,河内 亮周,岩本貢,山下 恭佑,齋藤 翔太
日本学術振興会, 科学研究費助成事業 基盤研究(A), 東京工業大学, 基盤研究(A), 23H00468
Apr. 2023 - Mar. 2027 - New theory for security analysis: from information inequality to computational inequality
渡辺 峻; 河内 亮周; 岩本 貢; 安永 憲司
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Tokyo University of Agriculture and Technology, Grant-in-Aid for Challenging Research (Pioneering), 23K17455
30 Jun. 2023 - 31 Mar. 2026 - 公開鍵暗号の識別不可能性に対する総合的評価技術の開発
四方順司
日本学術振興会, 科学研究費助成事業 基盤研究(B), 横浜国立大学, 基盤研究(B), 22H03590
01 Apr. 2022 - 31 Mar. 2026 - 真に高機能暗号の社会展開に資する物理・視覚暗号
花岡 悟一郎; Attrapadung Nuttapong; 松田隆宏; 品川和雅; 宮本賢伍; 岩本貢; 渡邉洋平; 宮原大輝; 水木敬明; 矢内直人; 山下恭佑
日本学術振興会, 科学研究費助成事業 基盤研究(A), 国立研究開発法人産業技術総合研究所, 基盤研究(A), 23H00479
Apr. 2023 - Mar. 2026 - 十分統計量に基づくシミュレーションベース安全性の深化
Mitsugu Iwamoto
日本学術振興会, 科学研究費助成事業 基盤研究(B), 電気通信大学, 基盤研究(B), 本年度は研究初年度であるため，基盤となる理論の検討を行いつつ，シミュレーションベース安全性に基づくいくつかの暗号方式を提案し，安全性証明を行った．具体的には秘密計算(Multi-Party Computation: MPC)，カードベース暗号，高機能暗号技術などが挙げられる． MPCについては，近年盛んに研究されている秘匿集合積プロトコルを扱った．Kolesnikovら(CCS2017)秘匿集合積計算の安全性証明を見直すことで，プロトコルの部品として用いられているOPPRF (Oblivious Programmable Pseudorandom Function) がプロトコルのある箇所では不必要な安全性を保証していることを見いだし，そこを削ったプロトコルに変更することでプロトコルの効率化に成功した． カードベース暗号では，秘匿積集合計算プロトコル，ｎ入力多数決プロトコルなどを扱った．我々が進めているカードベース暗号における秘匿置換の概念は，MPCやシミュレーションベース安全性と相性が良いことが分かっている．トランプのような物理的なカードを用いることで，安全性の直観もききやすく，本研究を進める上での重要な具体例になると考えている． 高機能暗号技術としては，鍵漏洩耐性暗号と検索可能暗号がある．どちらもシミュレーションベースで安全性を証明するが，鍵漏洩耐性暗号では「鍵が漏洩しても安全」であることを，検索可能暗号では「あまり重要でないと考えられる情報が漏洩しても安全」であることを数学的に保証する必要がある．どちらも情報が何らかの形で漏洩する場合が扱われており，その様な場合のシミュレーションベース安全性と十分統計量を考察するための重要な具体例になると考えて研究を進めている．また，どちらも計算量的に安全な方式であり，計算量的な統計量を考えるためにも重要である．, 21H03395
01 Apr. 2021 - 31 Mar. 2025 - Resilience Enhancement of IoT Ecosystem by Cryptographic Technologies
崎山一男
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S), The University of Electro-Communications, Grant-in-Aid for Scientific Research (S), リーク耐性暗号、リーク鍵の蒸留、及びリーク検知技術の3つの研究テーマの実績は以下の通りである。得られた成果は国内会議、国際会議、及び論文誌で発表した。 1)リーク耐性暗号： IDベース暗号について、マスター鍵が漏洩する場合でも安全となる構成法を提案した。また、復号鍵の漏洩に耐性のある鍵失効機能付きIDベース暗号の効率化に成功した。さらに、秘密鍵の盗難や紛失時の鍵漏洩耐性や秘密鍵自体の分散管理について検討した。カードベース暗号について、新しい物理道具を用いる秘密計算プロトコルを提案した。暗号利用モードについては、Lesamnta-LWの性能向上と応用について提案した。情報漏洩の形式的モデルへのフィードバックについては、演算器やマイクロアーキテクチャを精査し、新たな漏洩源を発見するとともに対策法を提案した。 2)リーク鍵の蒸留：AES暗号の秘密鍵復元において、検査フェイズを新たに導入し、従来0%の復元成功確率であった解析を約40%に向上することができた。プロービング攻撃への対策であるマスク実装について、あるブール関数を用いることで効率化できることを発見した。また、SHA-256圧縮関数の代数的故障利用解析やMAC関数chop-MDの偽造攻撃について、効率的な解析手法を考案した。チーム三浦／岩本との連携では、リキー方式の安全性と実装性を再考し、攻撃検知後に漏洩リスク下にある部分鍵を更新する新たな方式を構築した。この方式を搭載したAES暗号処理回路を設計した。 3)リーク検知技術：KU Leuven大と共同で作製したM&M技術により対策されたAES暗号ハードウェアの安全性評価を完了した。さらに連携を深めることで、リーケージセンサとアルゴリズムレベルでの対策技術の協調設計手法に着手できた。リーケージセンサについては、物理的なダイレクトプロービング攻撃の検知感度を高めた新たな回路を開発した。, 18H05289
11 Jun. 2018 - 31 Mar. 2023 - Searchable Symmetric Encryption for a Long Term Use
Kazuo Ohta
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), The University of Electro-Communications, Grant-in-Aid for Scientific Research (C), 検索可能暗号(Searchable Symmetric Encryption:SSE) はクラウドに暗号化したデータを預託して、キーワードによってデータを暗号化したまま検索を実行することを可能にする技術である。本研究では、共通鍵暗号ベースの検索方式が高速で暗号化と検索が可能なので早期に普及すると想定し、当該技術を用いて長期間にわたってサービスを継続することを目的として、暗号化データベースの維持管理として文書の集まりとキーワードの集まりの世代更新機能と、複数ユーザへの拡張性を保証できるデータベース蓄積・検索機能の実現方法について検討する。併せて、機能拡張に伴う安全性を再定義して、提案方式の効率向上と安全性証明を行う。 1年目は、単一ユーザ型で任意のタイミングでファイル・キーワードをサーバに登録可能な動的検索可能暗号(Dynamic SSE: DSSE) について特許出願した。単一ユーザに限定した場合の DSSE を実現できたので、世代更新機能の問題は解決した。 2年目は理論的には、既存の (D)SSE では扱いが不明確だった漏洩情報について「強フォワード安全性」と呼ぶ安全性概念を定式化する学術的な貢献があった。 3年目は研究方針を変更して基本に返り、SSEの安全性を初めて定式化して安全性証明を与えた代表的論文(Curtmola et al. 2003年)を理論面および実装面の問題がないか精査し、SSE-1では予期しない条件で検索を行った場合に無限ループが発生する場合があり、SSE-2では安全性定義では許容されない情報が漏洩することを見つけた。また DSSE の安全性について研究動向を調査した。 4年目は、これらの問題を解決する方式を1年目に得られたDSSE方式と統合して本プロジェクトの成果として取りまとめて論文を作成して投稿した(査読結果待ち)。DSSEの調査を通じて提案されている有力な方式について安全性証明の欠陥を指摘し、その方式を基にDSSE方式を提案して国際会議（CODASPY2022）で発表した。, 18K11293
01 Apr. 2018 - 31 Mar. 2023 - A new look at security proofs of cryptographic primitives from logic
Iwamoto Mitsugu
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory), The University of Electro-Communications, Grant-in-Aid for Challenging Research (Exploratory), Principal investigator, In this study, we revisited the security proofs of cryptographic protocols from the viewpoint of logic and tried to understand them easily. As the tools for this purpose, we used so-called physical cryptography such as card-based protocols and private PEZ protocols, which have been studied extensively in recent years. Since the card-based protocols are based on the technique called a private permutation, the proposed protocols have a similar structure to ordinary (algebraic) multi-party computations. The security of private PEZ protocols is easier to understand compared to algebraic multi-party computations because it is free from simulation-based security. We proposed several new card-based and private PEZ protocols with higher efficiency, which contributed to understanding the security of cryptographic protocols simply. Some of these results have been published in international journals and major international conferences., 18K19780
29 Jun. 2018 - 31 Mar. 2022 - Developing a Paradigm for Constructions in Information Theoretic Cryptography and Its Applications
Shikata Junji
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Yokohama National University, Grant-in-Aid for Scientific Research (B), In order to develop information-theoretic cryptography, the purpose of this research is to construct complicated and advanced cryptographic protocols with information-theoretic security by a broad and systematic paradigm from both information theory and modern cryptography, and to apply resulting techniques to other research topics including construction of protocols with complexity-based security. The contribution of this research includes new constrictions of information-theoretically secure advanced protocols including fully homomorphic encryption and MPC including card-based protocols. In addition, from viewpoints of applications, our contribution includes new constructions of various advanced protocols with complexity-based security, and implementation analysis of randomness extractors and fully homomorphic encryption in resource-constrained devices., 18H03238
01 Apr. 2018 - 31 Mar. 2021 - Development of Information-Theoretic Security Based on Guessing Secrecy
Iwamoto Mitsugu
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), The University of Electro-Communications, Grant-in-Aid for Scientific Research (B), Principal investigator, In this study, we investigated the recently proposed information-theoretic security notion called guessing secrecy for developing information-theoretic security. First, we proposed several definitions of guessing secrecy and investigated their relationship. Then, by proposing several cryptographic protocols satisfying guessing secrecy, we found that the existence of the security gap depends on the protocols. We also measured the computation time required to guess a key of AES under a probing attack and clarified the relationship between guessing and computation time. Besides the study of guessing secrecy, we proposed several cryptographic protocols that satisfy perfect secrecy, especially secret sharing and multi-party computation., 17H01752
01 Apr. 2017 - 31 Mar. 2021 - A Unified Paradigm in Information Theoretic Cryptography and Its Applications
SHIKATA Junji
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Yokohama National University, Grant-in-Aid for Scientific Research (B), In this research project, we studied a unified paradigm in information theoretic cryptography which can deal with various security notions in cryptography and information theory from systematic and bird’s-eye viewpoints. By overlooking security notions of computational security and information-theoretic security from various aspects, we showed new formalizations of security, construction of cryptographic systems, and their relationships. In particular, we formalized various security notions of encryption and key agreement which have meaningful operations, and showed relationships among security formalizations including the existing ones. We also showed (im)possibility of information theoretic security for encryption, authentication and secret sharing only from biased randomness. Furthermore, as applications of this paradigm, we showed new security formalizations and/or new construction methodology for advanced cryptographic systems., 15H02710
01 Apr. 2015 - 31 Mar. 2018 - Construction and Analysis of Information Theoretically Secure Multicast Communication
Iwamoto Mitsugu
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), The University of Electro-Communications, Grant-in-Aid for Scientific Research (C), Principal investigator, We discussed how to unify broadcast encryption (BE) and secure network coding (SNC), and clarified that it is possible when the network is (t,d)-combinatorial network where a source node is connected to t intermediate nodes, and each sink node is connected to t intermediate nodes. Furthermore, the proposed scheme is highly practical compared to the original BE. For instance, 834TB and 809TB are necessary for encryption and decryption keys, respectively, to implement (≦100, ≦3)-BE by traditional method. On the other hand, in the case of (5,3)-combinatorial network, 2.6TB and 75GB are enough for encryption and decryption keys, respectively, by the proposed scheme. Key lengths of proposed scheme are not short, but are more practical compared to the traditional BE., 26420345
01 Apr. 2014 - 31 Mar. 2017 - Information Theoretic Cryptography with Statistical Cheating Detection and Its Applications
IWAMOTO Mitsugu
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B), The University of Electro-Communications, Grant-in-Aid for Young Scientists (B), In this research, we investigated the way of detecting cheating in information theoretic cryptography. In particular, we clarified that the trade-off between share size and the exponent of the success probability in impersonation attack on (2,2)-threshold secret sharing schemes. This result implies how we can easily detect the impersonation by making each share redundant. In addition, we proposed a method of preventing the cheating in visual secret sharing schemes (VSSS). We also discussed how to cheat the visual secret sharing schemes in a practical setting by focusing on the situation where VSSS is decrypted without computers. Other than the above, we clarified several fundamental results on information theoretic cryptography., 23760330
2011 - 2013 - Research on Attack Limits of Side-Channel Analysis and Clarification of Information Leakage Mechanism
SAKIYAMA Kazuo; OHTA Kazuo; IWAMOTO Mitsugu
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), The University of Electro-Communications, Grant-in-Aid for Scientific Research (C), Side-channel attacks are methods, where attackers retrieve secret information by using physical phenomena leaked from cryptographic hardware such as power consumption and electromagnetic radiation. Exploring the attack limits of side-channel analysis, this research focused on the clarification of information leakage. We succeeded in deriving the theoretical bound for the amount of information leakage, and extended the understanding of the relationship between secret and random information handled in cryptology., 22500008
2010 - 2012 - Development of a randomness test method based on T-complexity for cryptography
YAMAMOTO Hirosuke; KUNIHIRO Noboru; IWAMOTO Mitsugu
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research, The University of Tokyo, Grant-in-Aid for Challenging Exploratory Research, T-randomness test is proposed based on T-complexity and the performance of the test is evaluated by theoretical analyses and simulation. LZ-randomness test based on LZ-complexity has a defect such that its probability is discrete. But, it is shown that T-complexity has the ideal normal distribution and T-randomness test works well. RP-complexity, which has an intermediate characteristic between LZ-complexity and T-complexity, is also defined and evaluated., 22656085
2010 - 2011 - Theoretical Study for Practical Applications of Information Theoretically Secure Cryptosystems
IWAMOTO Mitsugu
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B), The University of Electro-Communications, Grant-in-Aid for Young Scientists (B), We studied information theoretically secure cryptosystems in order to make them more practical. As a result, we obtained three results along with this research direction. Three main results are : (1) coding theorems for (2,2)-threshold secret sharing schemes secure against cheaters, (2) a proposal of efficient visual secret sharing schemes by relaxing information theoretical security notion, and (3) a new look at relations among information theoretically secure and computationally secure symmetric key encryptions. Furthermore, we obtained several results in cryptography and information security in which information theoretic methods are effectively utilized., 20760236
2008 - 2010 - 逐次検定と乱数生成の情報スペクトル理論
韓 太舜; 岩本 貢
日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 本研究では、情報理論的諸問題へ適用されて成功をおさめている情報スペクトル的方法を大偏差問題に適用してその理論体系を再構築した。, 19560372
2007 - 2009 - 情報理論的に安全な多重符号化に関する符号化定理とその応用
山本 博資
日本学術振興会, 科学研究費助成事業 萌芽研究, 東京大学, 萌芽研究, 安全な多重符号化法に関して,本年度は下記の成果を得た. 1.盗聴通信路(盗聴者がいる雑音のある通信路)では,符号化法を工夫することにより,秘密鍵を一切使用しなくても秘密情報を安全に伝送可能なことが知られている.昨年度は,複数の秘密情報を一度に多重符号化することにより,盗聴通信路を通して個々の情報を完全に安全に保ちながら,全体の情報伝送レートを通信路容量まで大きくできることを理論的に明らかにした.本年度は,無記憶通信路および情報スペクトル理論の意味での一般通信路の場合に対して,その証明を洗練したものに改良した. 2.通信ネットワーク上で互いに情報を交換するとき,後出しなどの不正が問題となる.そのような不正を防止する基礎技術としてビットコミットメントがあるが,盗聴通信路の符号化法を利用してビットコミットメントを実現できる.昨年度は,上記1で示した盗聴通信路に対する多重符号化法をビットコミットメントに適用できることを示したが,本年度はその符号化定理の証明法についても改良を行った. 3.インターネットのような複雑なネットワークを通して情報を効率よく伝送するための符号化をネットワーク符号化という.ネットワーク符号化で,盗聴者が盗聴できる通信路数に制限がある場合に,安全な符号化が可能なことが知られているが,それらは単一の情報に対する符号化法であった.本年度の研究において,複数の受信者に対する共通情報とそれぞれの受信者への個別情報を同時に安全に符号化できる可能性があることを明らかにした., 18656110
2006 - 2007 - 高い符号化効率を実現するランプ型秘密分散法の構成とその安全性評価
岩本 貢
日本学術振興会, 科学研究費助成事業 若手研究(B), 電気通信大学, 若手研究(B), 本年度は,partial broadcast channelを用いた秘密分散法に関して研究を行う予定であったが,残念ながら,まとまった結果を得ることが出来なかった.そのため途中から,不正者に対する耐性を持つ秘密分散法を情報理論的に構成する方法を研究した.従来の設定では,完全に不正を防ぐ(不正者の不正成功確率を0にするということ)は不可能であるという結果があるが(Ogata, et. al.),設定をShannon理論的な設定に(わずかに)変更するだけでこの問題が回避できるのではないかというのが,本研究の重要な点である.この問題については平成19年度中に解決を見ることが出来こなかったが最近,認証に関するShannon理論的暗号システムの扱いに関する論文(Koga, et. al.)においても似たような議論が成立していることに気がついた.引き続き研究していく予定である. 続いて,ランプ型のVSSSに関しては,理論的な研究が完成せず,論文として発表するにはもう一工夫が必要である.しかし,情報漏洩と秘密画像のサイズに関して現在までに得られている新しい知見については平成20年度中に開催される国際会議に投稿の予定である. 昨年度にある程度論文が出版されたこともあって,研究期間最終年としては来年度以降に引き続き行うべき点が多く残ったことが残念ではあるが,平成20年度以降も研究としては続けていき,成果を発表していく予定である.また,研究課題に関しては昨年度までの結果も含め,一定の成果があったと感じている., 17760298
2005 - 2007 - 秘密分散法に対する情報理論的性能解析とその一般的構成法に関する研究
山本 博資
日本学術振興会, 科学研究費助成事業 特定領域研究, 東京大学, 特定領域研究, 秘密分散法(SSS)は,秘密情報Sをn個の分散情報に分散符号化し,有資格集合に属する分散情報が全て集まるとSが復号できるが,禁止集合に属する分散情報が集まってもSに関して全く情報が漏れない符号化方式である. 分散情報の任意の部会集合が,有資格集合または禁止集合のどちらかである場合,そのSSSのアクセス構造は完全であるという.また,有資格集合でも禁止集合でもない中間的な特性を持つ分散情報の集合が存在するとき,そのSSSのアクセス構造はランプ型であるという.有資格集合と禁止集合が,分散情報の部分集合のサイズにより決まるとき,アクセス構造はしきい値型であるという.特に,分散情報の部分集合のサイズがk以上で有資格集合,サイズがk-L以下で禁止集合,サイズがk-t(1≦t≦L)で秘密情報Sに対して(t/L)H(S)の曖昧さが残るランプ型SSSを,(k,L,n)しきい値ランプ型SSSといい,L=1の場合を(k,n)しきい値SSSという.また,しきい値型に限らないアクセス構造を,一般アクセス構造という. 通常のSSSでは,秘密情報は数値情報であるが,将来,量子計算機や量子通信が実現し,量子状態を長期に記憶できるようになると,量子状態そのものを秘密情報として保管したい場合がある.そのような量子状態を符号化するSSSを,量子秘密分散法という. 本年度は本特定領域研究の最終年であり,今までの研究成果の取りまとめを行うとともに,本研究を通じて得られた「量子秘密分散法」および「一般アクセス構造に対する強いランプ型秘密法」に関する研究成果を論文誌に発表した.さらに,本年度新たにネットワーク符号化(Network Coding)へのしきい値ランプ型秘密分散法の応用に関して研究を行い,その成果をシンポジウムにおいて発表した., 16016224
2004 - 2005
Industrial Property Rights
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