Takoro Shiraya, Subhadeep Banik, Tatsuya Ishikawa, Ryoma Ito, Mostafizar Rahman, Kosei Sakamoto, Atsushi Tanaka, Shion Utsumi, and Takanori Isobe. Exploring SHA Instructions and Its Application to AES-based Schemes. IACR Communications in Cryptology, Vol. 2, Issue 3, pp. XXX-XXX. Oct. 2025.
Kosei Sakamoto, Ryoma Ito, and Takanori Isobe. Parallel SAT Framework to Find Clustering of Differential Characteristics and Its Applications. Journal of Information Security and Applications, vol. 94, no. 104203, Sep. 2025. (IF = 3.7).
Kazuma Taka, Kosei Sakamoto, Ryoma Ito, Rentaro Shiba, Shion Utsumi, and Takanori Isobe. Divide-and-Conquer SAT for Exploring Optimal Differential and Linear Characteristics and Its Applications. IACR Transactions on Symmetric Cryptology, Vol. 2025, Issue 3, pp. 516-576, Sep. 2025.
Hayato Watanabe, Ryoma Ito, and Toshihiro Ohigashi. On the Effects of Neural Network-based Output Prediction Attacks on the Design of Symmetric-key Ciphers. Journal of Information Security and Applications, vol. 90, no. 104046, May. 2025. (IF = 3.8).
Takanori Isobe, Ryoma Ito, and Kazuhiko Minematsu. Security Analysis of SFrame. Journal of Information Security and Applications, vol. 89, no. 103958, Mar. 2025. (IF = 3.8).
Yu Long Chen, Antonio Flórez-Gutiérrez, Akiko Inoue, Ryoma Ito, Tetsu Iwata, Kazuhiko Minematsu, Nicky Mouha, Yusuke Naito, Ferdinand Sibleyras, and Yosuke Todo. Key Committing Security of AEZ and More. IACR Transactions on Symmetric Cryptology, Vol. 2023, No. 4, pp. 452-488, Dec. 2023.
Takanori Isobe, Ryoma Ito, and Kazuhiko Minematsu. Cryptanalysis on End-to-End Encryption Schemes of Communication Tools and Its Research Trend. Journal of Information Processing, vol. 31, pp. 523-536, Sep. 2023. [Invited Paper]
Hayato Kimura, Keita Emura, Takanori Isobe, Ryoma Ito, Kazuto Ogawa, and Toshihiro Ohigashi. A Deeper Look into Deep Learning-based Output Prediction Attacks Using Weak SPN Block Ciphers. Journal of Information Processing, vol. 31, pp. 550-561, Sep. 2023. [JIP Specially Selected Paper]
Nasratullah Ghafoori, Atsuko Miyaji, Ryoma Ito, and Shotaro Miyashita. PNB Based Differential Cryptanalysis of Salsa20 and ChaCha. IEICE Trans. Information and Systems, vol. E106-D, no.9, pp. 1407-1422, Sep. 2023.
Takanori Isobe, Ryoma Ito, Fukang Liu, Kazuhiko Minematsu, Motoki Nakahashi, Kosei Sakamoto, and Rentaro Shiba. Areion: Highly-Efficient Permutations and Its Applications to Hash Functions for Short Input. IACR Transactions on Cryptographic Hardware and Embedded Systems, Vol. 2023, Issue 2, pp. 115-154, Mar. 2023.
Akinori Hosoyamada, Akiko Inoue, Ryoma Ito, Tetsu Iwata, Kazuhiko Minematsu, Ferdinand Sibleyras, and Yosuke Todo. Cryptanalysis of Rocca and Feasibility of Its Security Claim. IACR Transactions on Symmetric Cryptology, Vol. 2022, Issue 3, pp. 123-151, Sep. 2022. (CiteScore = 5.7).
Fukang Liu, Willi Meier, Santanu Sarkar, Gaoli Wang, Ryoma Ito, and Takanori Isobe. New Cryptanalysis of ZUC-256 Initialization Using Modular Differences. IACR Transactions on Symmetric Cryptology, Vol. 2022, Issue 3, pp. 152-190, Sep. 2022. (CiteScore = 5.7).
Jin Hoki, Takanori Isobe, Ryoma Ito, Fukang Liu, and Kosei Sakamoto. Distinguishing and Key Recovery Attacks on the Reduced-Round SNOW-V and SNOW-Vi. Journal of Information Security and Applications, vol. 65, no. 103100, Mar. 2022. (IF = 4.960).
Takanori Isobe and Ryoma Ito. Security Analysis of End-to-End Encryption for Zoom Meetings. IEEE Access, vol. 9, pp. 90677-90689, Jun. 2021. (IF = 3.367).
Ryoma Ito, Rentaro Shiba, Kosei Sakamoto, Fukang Liu, and Takanori Isobe. Bit-wise Cryptanalysis on AND-RX Permutation Friet-PC. Journal of Information Security and Applications, vol. 59, no. 102860, Jun. 2021. (IF = 3.872).
Ryoma Ito and Atsuko Miyaji. New Iterated RC4 Key Correlations and Their Application to Plaintext Recovery on WPA-TKIP. IEICE Trans. Fundamentals, vol. E104-A, no. 1, pp. 190–202, Jan. 2021.
Ryoma Ito and Atsuko Miyaji. Refined Construction of RC4 Key Setting in WPA. IEICE Trans. Fundamentals, vol. E100-A, no. 1, pp. 138–148, Jan. 2017.
Ryoma Ito and Atsuko Miyaji. Refined RC4 Key Correlations of Internal States in WPA. IEICE Trans. Fundamentals, vol. E99-A, no. 6, pp. 1132-1144, Jun. 2016.
Ryoma Ito and Atsuko Miyaji. Refined Glimpse Correlations of RC4. IEICE Trans. Fundamentals, vol. E99-A, no. 1, pp.3-13, Jan. 2016.
Hayato Kimura, Ryoma Ito, Kazuhiko Minematsu, and Takanori Isobe. Gravity of the Situation: Security Analysis on Rocket.Chat E2EE. In 41th IEEE Annual Computer Security Applications Conference - ACSAC 2025, pages XXX-XXX. IEEE, 2025. (acceptance rate: 20.7% = 84/406)
Hayato Kimura, Ryoma Ito, Kazuhiko Minematsu, Shogo Shiraki, and Takanori Isobe. Not in The Prophecies: Practical Attacks on Nostr. In 10th IEEE European Symposium on Security and Privacy - EuroS&P 2025, pages 585-606. IEEE, 2025. (acceptance rate: 21.9% = 60/273) [Web]
Kodai Taiyama, Kosei Sakamoto, Ryoma Ito, Kazuma Taka, and Takanori Isobe. Key Collisions on AES and Its Applications. In Kai-Min Chung and Yu Sasaki, editors, Advanced in Cryptology - Asiacrypt 2024, volume 15490 of Lecture Notes in Computer Science, pages 267–300. Springer International Publishing, 2024. (acceptance rate: 29.2% = 127/435) [slide]
Hayato Watanabe, Ryoma Ito, and Toshihiro Ohigashi. On the Effects of Neural Network-based Output Prediction Attacks on the Design of Symmetric-key Ciphers. In Michael Elhadad, Mirosław Kutyłowski, and Giuseppe Persiano, editors, Cyber Security, Cryptology, and Machine Learning - CSCML 2024, volume 15349 of Lecture Notes in Computer Science, pages 201–218. Springer International Publishing, 2024. (acceptance rate: 37.2% = 16/43) [slide]
Kosei Sakamoto, Ryoma Ito, and Takanori Isobe. Parallel SAT Framework to Find Clustering of Differential Characteristics and Its Applications. In Claude Carlet, Kalikinkar Mandal, and Vincent Rijmen, editors, Selected Area in Cryptography - SAC 2023, volume 14201 of Lecture Notes in Computer Science, pages 409–428. Springer International Publishing, 2023. (acceptance rate: 43.7% = 21/48)
Hayato Kimura, Keita Emura, Takanori Isobe, Ryoma Ito, Kazuto Ogawa, and Toshihiro Ohigashi. Output Prediction Attacks on Block Ciphers using Deep Learning. In Sridhar Adepu and Cristina Alcaraz, editors, Artificial Intelligence and Industrial Internet-of-Things Security - AIoTS 2022, volume 13285 of Lecture Notes in Computer Science, pages 248–276. Springer International Publishing, 2022. (acceptance rate: 59.6% = 31/52).
Shotaro Miyashita, Ryoma Ito, and Atsuko Miyaji. PNB-focused Differential Cryptanalysis of ChaCha Stream Cipher. In Guomin Yang and Khoa Nguyen, editors, Australasian Conference on Information Security and Privacy - ACISP 2022, volume 13494 of Lecture Notes in Computer Science, pages 46–66. Springer International Publishing, 2022. (acceptance rate: 40.3% = 25/62).
Keita Emura, Ryoma Ito, Sachiko Kanamori, Ryo Nojima, and Yohei Watanabe. State-free End-to-End Encrypted Storage and Chat Systems based on Searchable Encryption. In Proceedings of the 24th International Conference on Enterprise Information Systems - Volume 2: ICEIS, SCITEPRESS, pages 106-113, 2022. (acceptance rate: 32.0% = 63/197).
Takanori Isobe, Ryoma Ito, and Kazuhiko Minematsu. Security Analysis of SFrame. In Elisa Bertino and Haya Shulman, editors, European Symposium on Research in Computer Security - ESORICS 2021, volume 12973 of Lecture Notes in Computer Science, pages 127–146. Springer International Publishing, 2021. (acceptance rate: 20.2% = 71/351). [slide]
Takanori Isobe and Ryoma Ito. Security Analysis of End-to-End Encryption for Zoom Meetings. In Joonsang Baek and Sushmita Ruj, editors, Australasian Conference on Information Security and Privacy - ACISP 2021, volume 13083 of Lecture Notes in Computer Science, pages 234–253. Springer International Publishing, 2021. (acceptance rate: 22.2% = 35/157). [slide]
Jin Hoki, Takanori Isobe, Ryoma Ito, Fukang Liu, and Kosei Sakamoto. Distinguishing and Key Recovery Attacks on the Reduced-Round SNOW-V. In Joonsang Baek and Sushmita Ruj, editors, Australasian Conference on Information Security and Privacy - ACISP 2021, volume 13083 of Lecture Notes in Computer Science, pages 171–190. Springer International Publishing, 2021. (acceptance rate: 22.2% = 35/157). [slide]
Ryoma Ito. Rotational Cryptanalysis of Salsa Core Function. In Willy Susilo and Robert H. Deng, editors, International Conference on Information Security - ISC 2020, volume 12472 of Lecture Notes in Computer Science, pages 129–145. Springer International Publishing, 2020. (acceptance rate: 26.4% = 23/87). [slide]
Ryoma Ito and Atsuko Miyaji. New Iterated RC4 Key Correlations. In Willy Susilo and Guomin Yang, editors, Australasian Conference on Information Security and Privacy - ACISP 2018, volume 10946 of Lecture Notes in Computer Science, pages 154–171. Springer International Publishing, 2018. (acceptance rate: 30.1% = 41/136). [slide]
Ryoma Ito and Atsuko Miyaji. How TKIP Induces Biases of Internal States of Generic RC4. In Ernest Foo and Douglas Stebila, editors, Australasian Conference on Information Security and Privacy - ACISP 2015, volume 9144 of Lecture Notes in Computer Science, pages 329–342. Springer International Publishing, 2015. (acceptance rate: 25.0% = 28/112). [slide]
Ryoma Ito and Atsuko Miyaji. New Linear Correlations Related to State Information of RC4 PRGA Using IV in WPA. In Gregor Leander, editors, Fast Software Encryption - FSE 2015, volume 9054 of Lecture Notes in Computer Science, pages 557–576. Springer Berlin Heidelberg, 2015. (acceptance rate: 39.4% = 28/71). [slide]
Ryoma Ito and Atsuko Miyaji. New Integrated Long-Term Glimpse of RC4. In Kyung-Hyune Rhee and Jeong Hyun Yi, editors, Information Security Application - WISA 2014, volume 8909 of Lecture Notes in Computer Science, pages 137–149. Springer International Publishing, 2015. (acceptance rate: 44.9% = 31/69). [slide]
Hayato Kimura, Ryoma Ito, Kazuhiko Minematsu, Shogo Shiraki, and Takanori Isobe, Not in The Prophecies: Practical Attacks on Nostr. Cryptology ePrint Archive: Report 2025/1459, August 2025.
Kodai Taiyama, Kosei Sakamoto, Ryoma Ito, Kazuma Taka, and Takanori Isobe. Key Collisions on AES and Its Applications. Cryptology ePrint Archive: Report 2024/1508, September 2024.
Hayato Watanabe, Ryoma Ito, and Toshihiro Ohigashi. On the Effects of Neural Network-based Output Prediction Attacks on the Design of Symmetric-key Ciphers. Cryptology ePrint Archive: Report 2024/1310, August 2024.
Kosei Sakamoto, Ryoma Ito, and Takanori Isobe. Parallel SAT Framework to Find Clustering of Differential Characteristics and Its Applications. Cryptology ePrint Archive: Report 2023/1227, August 2023.
Takanori Isobe, Ryoma Ito, Fukang Liu, Kazuhiko Minematsu, Motoki Nakahashi, Kosei Sakamoto, and Rentaro Shiba. Areion: Highly-Efficient Permutations and Its Applications (Extended Version). Cryptology ePrint Archive: Report 2023/794, June 2023.
Shotaro Miyashita, Ryoma Ito, and Atsuko Miyaji. PNB-focused Differential Cryptanalysis of ChaCha Stream Cipher. Cryptology ePrint Archive: Report 2021/1537, November 2021.
Fukang Liu, Willi Meier, Santanu Sarkar, Gaoli Wang, Ryoma Ito, and Takanori Isobe. New Cryptanalysis of ZUC-256 Initialization Using Modular Differences. Cryptology ePrint Archive: Report 2021/1104, August 2021.
Keita Emura, Ryoma Ito, Sachiko Kanamori, Ryo Nojima, and Yohei Watanabe. State-free End-to-End Encrypted Storage and Chat Systems based on Searchable Encryption. Cryptology ePrint Archive: Report 2021/953, July 2021.
Jin Hoki, Takanori Isobe, Ryoma Ito, Fukang Liu, and Kosei Sakamoto. Distinguishing and Key Recovery Attacks on the Reduced-Round SNOW-V and SNOW-Vi. Cryptology ePrint Archive: Report 2021/546, April 2021.
Takanori Isobe and Ryoma Ito. Security Analysis of End-to-End Encryption for Zoom Meetings. Cryptology ePrint Archive: Report 2021/486, April 2021.
Takanori Isobe, Ryoma Ito, and Kazuhiko Minematsu. Security Analysis of SFrame. Cryptology ePrint Archive: Report 2021/424, April 2021.
Hayato Kimura, Keita Emura, Takanori Isobe, Ryoma Ito, Kazuto Ogawa, and Toshihiro Ohigashi. Output Prediction Attacks on Block Ciphers using Deep Learning. Cryptology ePrint Archive: Report 2021/401, March 2021.
Ryoma Ito, Rentaro Shiba, Kosei Sakamoto, Fukang Liu, and Takanori Isobe. Bit-wise Cryptanalysis on AND-RX Permutation Friet-PC. Cryptology ePrint Archive: Report 2021/212, March 2021.
白矢琢朗, 石川達也, 伊藤竜馬, Mostafizar Rahman, 阪本光星, 田中篤, 内海潮音, 五十部孝典. SHA Extensionsを用いたAES-basedハッシュ関数の拡張. コンピュータセキュリティシンポジウム 2025 - CSS 2025, 1G2-2, 2025-10.
名古屋太一, 白矢琢朗, 高和真, 石川達也, 阪本光星, 伊藤竜馬, 五十部孝典. LeMac-0/LeMacの偽造攻撃に対する安全性評価. コンピュータセキュリティシンポジウム 2025 - CSS 2025, 1G2-3, 2025-10.
森田健斗, 石川達也, 白矢琢朗, 阪本光星, 伊藤竜馬, 五十部孝典. 低遅延暗号 Gleeok の差分攻撃に対する安全性評価. コンピュータセキュリティシンポジウム 2025 - CSS 2025, 1G2-4, 2025-10.
白木章伍, 木村隼人, 伊藤 竜馬, 峯松一彦, 五十部孝典. WhatsAppに対する不正デバイス登録攻撃. コンピュータセキュリティシンポジウム 2025 - CSS 2025, 3G3-2, 2025-10.
中川大輔, 田中篤, 木村隼人, 山下恭佑, 伊藤竜馬, 五十部孝典. なりすまし攻撃に対するThreemaハンドシェイクプロトコルの形式検証. コンピュータセキュリティシンポジウム 2025 - CSS 2025, 3G3-3, 2025-10.
松本岳大, 田中篤, 山下恭佑, 伊藤竜馬, 五十部孝典. LINE Letter Sealingに対するTamarin-Proverを用いた網羅的安全性検証. コンピュータセキュリティシンポジウム 2025 - CSS 2025, 3G3-4, 2025-10.
巽浩太, 渡部颯斗, 伊藤竜馬, 大東俊博. SIMONバリアントに対する拡散性能評価の厳密化. 信学技報, vol. 125, no. 99, ISEC2025-56, pp. 258-265, July 2025.
渡部颯斗, 伊藤竜馬, 大東俊博. 機械学習ベース出力予測攻撃のモデル比較とその解釈可能性. 信学技報, vol. 124, no. 422, ICSS2024-121, pp. 407-414, 2025-3.
木村隼人, 伊藤竜馬, 峯松一彦, 五十部孝典. ロケットチャットのエンドツーエンド暗号化に対する安全性解析. 2025年 暗号と情報セキュリティシンポジウム - SCIS 2025, 2C2-2, 2025–1. [SCIS論文賞]
木村隼人, 白木章伍, 伊藤竜馬, 峯松一彦, 五十部孝典. Link Previewを介した暗号化DMに対する平文回復攻撃. コンピュータセキュリティシンポジウム 2024 - CSS 2024, 1H6-1, 2024-10. [優秀論文賞] [エシカルプラクティス賞]
泰山幸大, 阪本光星, 伊藤竜馬, 髙和真, 五十部孝典. AESのDavies-Meyerモードに対する衝突攻撃. 信学技報, vol. 124, no. 120, ISEC2024-19, pp. 73-80, July 2024. [情報セキュリティ研究賞]
日吉敬祐, 渡部颯斗, 伊藤竜馬, 大東俊博. DNNによるRTT予測誤差に基づく乱数生成法の提案と評価. 研究報告コンピュータセキュリティ - CSEC 2024, 2024–CSEC–106, pages 413–419, 2024–7.
木村隼人, 伊藤竜馬, 峯松一彦, 五十部孝典. 分散型SNSプロトコルNostrに対する改ざん攻撃の網羅的調査. 信学技報, vol. 123, no. 448, ICSS2023-69, pp. 1-8, 2024-3.
渡部颯斗, 伊藤竜馬, 大東俊博. SIMONバリアントの脆弱な構造の特定. 信学技報, vol. 123, no. 448, ICSS2023-92, pp. 166-173, 2024-3.
髙和真, 阪本光星, 伊藤竜馬, 芝廉太朗, 内海潮音, 五十部孝典. 分割統治法SATを用いたAESとCamelliaの最大差分/線形特性確率の導出. 2024年 暗号と情報セキュリティシンポジウム - SCIS 2024, 3C4-3, 2024–1. [イノベーション論文賞]
渡部颯斗, 伊藤竜馬, 大東俊博. 深層学習ベースの出力予測攻撃が共通鍵暗号設計に及ぼす影響. 2024年 暗号と情報セキュリティシンポジウム - SCIS 2024, 1C2-2, 2024–1.
木村隼人, 伊藤竜馬, 峯松一彦, 五十部孝典. 分散型SNSプロトコルNostrに対する改ざん攻撃. コンピュータセキュリティシンポジウム 2023 - CSS 2023, 2E4-3, 2023-11. [学生論文賞]
中橋元輝, 芝廉太郎, 阪本光星, Fukang Liu, 伊藤竜馬, 峯松一彦, 五十部孝典. AES instructionを用いたラージブロック置換の改良とその応用. 信学技報, vol. 121, no. 429, ISEC2022-80, pp. 188-195, March 2022.
五十部孝典, 伊藤竜馬, 峯松一彦. エンドツーエンド暗号化SFrameに対する安全性評価. コンピュータセキュリティシンポジウム 2021 - CSS 2021, 2E3-3, 2021-10. [slide] [奨励賞] [山下記念研究賞]
宮下翔太郎, 伊藤竜馬, 宮地充子. PNB解析に基づくストリーム暗号Salsa20への差分攻撃. 2021年電子情報通信学会総合大会, A-7-4, 2021-3.
五十部孝典, 伊藤竜馬. Zoomのエンドツーエンド暗号化に対する安全性評価. 2021年 暗号と情報セキュリティシンポジウム - SCIS 2021, 3B3–1, 2021–1. [slide] [イノベーション論文賞]
木村隼人, 江村恵太, 五十部孝典, 伊藤竜馬, 小川一人, 大東俊博. 深層学習を用いたSPNブロック暗号への出力予測攻撃. 2021年 暗号と情報セキュリティシンポジウム - SCIS 2021, 1B1–1, 2021–1.
宮下翔太郎, 伊藤竜馬, 宮地充子. ストリーム暗号Salsa20におけるProbabilistic Neutral Bitsの解析. コンピュータセキュリティシンポジウム 2020 - CSS 2020, 2E1-3, 2020-10.
伊藤竜馬, 宮地充子. 反復性のある鍵相関を用いた WPA-TKIP に対する平文回復攻撃. 信学技報, vol. 118, no. 151, ISEC2018-48, pp. 379-386, July 2018. [slide]
伊藤竜馬, 宮地充子. ストリーム暗号 RC4 における反復性のある新しい鍵相関. 2018年 暗号と情報セキュリティシンポジウム - SCIS 2018, 2B3–1, 2018–1. [slide]
道廣大喜, 宮地充子, 伊藤竜馬. WPA における RC4 の鍵回復攻撃に向けた新しい線形相関と解析手法. 信学技報, vol. 114, no. 489, ICSS2014-85, pp. 133-138, March 2015.
伊藤竜馬, 宮地充子. WPA における RC4 の内部状態に関する新しい線形相関. 2015年 暗号と情報セキュリティシンポジウム - SCIS 2015, 2E2–3, 2015–1. [slide] [SCIS論文賞]
伊藤竜馬, 宮地充子. RC4 の Long-term Glimpse における新しい Negative Biases. 信学技報, vol. 114, no. 24, ISEC2014-3, pp. 13-19, May 2014. [slide]
伊藤竜馬, 岩切宗利. 非線形変換を含む単純化ストリーム暗号 KCipher-2 への GD 攻撃. 研究報告コンピュータセキュリティ - CSEC 2013, 2013–CSEC–7, pages 1–7, 2013–3.
伊藤竜馬, 岩切宗利. 単純化ストリーム暗号 K2 のクロック制御を無効化した GD 攻撃. 研究報告コンピュータセキュリティ - CSEC 2013, 2013–CSEC–6, pages 1–6, 2013–3.
CRYPTREC暗号技術評価委員会, CRYPTREC 暗号技術ガイドライン（軽量暗号）2023年度版, 2024年4月（CRYPTREC事務局の主担当として執筆・編集を担当）.
Yu Long Chen, Antonio Flórez-Gutiérrez, Akiko Inoue, Ryoma Ito, Tetsu Iwata, Kazuhiko Minematsu, Nicky Mouha, Yusuke Naito, Ferdinand Sibleyras, and Yosuke Todo. Key Committing Security of AEZ. The Third NIST Workshop on Block Cipher Modes of Operation 2023, Oct. 2023.
伊藤竜馬, 「CRYPTREC 暗号技術ガイドライン（軽量暗号）」掲載の暗号方式に関する安全性評価の動向調査. CRYPTREC, 2022.4.13.