Ryoma Ito
Senior Researcher,
Security Fundamentals Laboratory,
Cybersecurity Research Institute,
National Institute of Information and Communications Technology.
4-2-1, Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan
Contact: itorym (at) nict.go.jp
News
February 2023: I was invited to the Program Committee member for ACISP 2024, ISC 2024, and FSE 2025 and the Editorial Board member for ToSC 2024/2025.
January 2024: I attended the Dagstuhl Seminar - 24041: symmetric cryptography.
November 2023: A journal paper was accepted to ToSC 2023.
Key Committing Security of AEZ and More
November 2023: I was invited to the Publication Chair for IWSEC 2024.
October 2023: I was invited to the Program Committee member for ADSC 2024.
October 2023: A workshop paper was presented at The Third NIST Workshop on Block Cipher Modes of Operation 2023.
Key Committing Security of AEZ
September 2023: A journal paper was granted a Specially Seleceted Paper certificate in Journal of Information Processing.
A Deeper Look into Deep Learning-based Output Prediction Attacks Using Weak SPN Block Ciphers
July 2023: A conference paper was accepted to SAC 2023.
Parallel SAT Framework to Find Clustering of Differential Characteristics and Its Applications
June 2023: Two journal paper were accepted to Journal of Information Processing.
Cryptanalysis on End-to-End Encryption Schemes of Communication Tools and Its Research Trend [Invited Paper]
A Deeper Look into Deep Learning-based Output Prediction Attacks Using Weak SPN Block Ciphers
Education
2017-2019: Ph.D. in Engineering, Osaka University, Japan (Supervisor: Prof. Atsuko Miyaji).
A Study on Statistical Cryptanalysis of Stream Ciphers [Doctoral Dissertation] [Ph.D. Defense]
2013-2015: Master's Degree in Information Science, Japan Advanced Institute of Science and Technology, Japan (Supervisor: Prof. Atsuko Miyaji).
2005-2009: Bachelor's Degree in Science and Technology, National Defense Academy, Japan.
Work Experiences
2020-: Senior Researcher, Security Fundamentals Laboratory, Cybersecurity Research Institute, National Institute of Information and Communications Technology, Japan.
2009-2020: Information and Communications Officer, Kokujieitai (Japan Air Self-Defense Force), Ministry of Defense, Japan.
Research Interests
Cryptanalysis of Symmetric Key Ciphers
Analysis on block ciphers: AES, PRESENT, TWINE, PRINCE, QARMA
Deep learning-based output prediction attacks on AES, PRESENT, and TWINE [conference paper] [journal paper] [ePrint]
SAT-based differential attacks on PRINCE and QARMA [conference paper] [ePrint]
Analysis on stream ciphers: RC4, Salsa, ChaCha, SNOW-V, SNOW-Vi, ZUC-256
Statistical cryptanalysis on RC4 [journal paper]
Rotational attacks on Salsa [conference paper]
Differential attacks on Salsa and ChaCha [journal paper] [ePrint]
Differential and integral attacks on SNOW-V and SNOW-Vi [journal paper]
Differential attacks on ZUC-256 [journal paper]
Analysis on AEADs: Rocca, AEZ, Adiantum, and HCTR2
Analysis on the initial version of Rocca [journal paper]
Analysis on key committing security of AEZ, Adiantum, and HCTR2 [journal paper] [NIST workshop]
Analysis on cryptographic permutations: Friet-PC
Rotational, differential, and integral attacks on Friet-PC [journal paper]
Design of Symmetric Key Ciphers
Areion: ultra low-latency permutation and its applications to hash functions and AEADs [journal paper] [ePrint] [Internet Draft]
Security Analysis of Real-world Systems
Statistical analysis and plaintext recovery attacks on RC4 under WPA-TKIP [journal paper 1] [journal paper 2] [journal paper 3]
Analysis of end-to-end encryption (E2EE): Zoom, Google Duo, Cisco Webex, Jitsi Meet
Analysis of E2EE for Zoom meetings [journal paper] [invited paper]
Analysis of E2EE framework: SFrame [conference paper] [ePrint]
Development of an encrypted system with keyword search (ESKS) [conference paper] [ePrint]
Publications
Peer-reviewed Journal Papers
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.
Peer-reviewed International Conference Papers
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.
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]
Other International Conference Papers
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.
Preprint Papers
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.
Others
Awards
2023: CSS Student Paper Award, IPSJ, Japan.
2023: JIP Specially Seleceted Paper certificate, IPSJ, Japan.
2023: IPSJ Yamashita SIG Research Award, IPSJ, Japan.
2022: SCIS Innovation Paper Award, SCIS 2021, ISEC group of IEICE, Japan.
2021: CSS Encouragement Research Award, CSS 2021, CSEC group of IPSJ, Japan.
2016: SCIS Paper Award, SCIS 2015, ISEC group of IEICE, Japan.
2015: Best Student Award, Japan Advanced Institute of Science and Technology, Japan.
2009: Best Student Award, National Defense Academy, Japan.
Professional Activities
Editorial Board: ToSC 2022/2023, ToSC 2023/2024, ToSC 2024/2025
Program Committee: FSE 2023, ADSC 2023, FSE 2024, ADSC 2024, ACISP 2024, ISC 2024, FSE 2025
Publication Chair: IWSEC 2024
Publicity Chair: ISPEC 2022