Takanori Isobe

I am a Professor at The University of Osaka. Prior to this, I worked at Sony Corporation from 2008 to 2017 (nine years) as a researcher in information security and cryptography. I was a Visiting Researcher at the Technical University of Denmark from 2014 to 2015. From 2017 to 2024, I served as an (Associate) Professor at the University of Hyogo.

Recruiting: We are looking for PhD candidates and Post-doc researchers in the field of Symmetric Cryptography and Applied Cryptography. Please contact me if you are interested.

News

April 2025, I joined The University of Osaka as Professor and PI of the Cryptography Engineering Lab.
February 2025, our paper is accepted to IEEE Euro S&P 2025,
- Not in The Prophecies: Practical Attacks on Nostr
December 2024, our paper is accepted to IACR CIC 2025
- On the Key-Commitment Properties of Forkcipher-based AEADs
December 2024, our paper is accepted to TCHES 2025
- AETHER: An Ultra-High Throughput and Low Energy Authenticated Encryption Scheme
August 2024, our paper is accepted to ASIACRYPT 2024
- Key Collisions on AES and Its Applications
January 2024, our paper is accepted to ToSC 2024
- "Key Committing Attacks against AES-based AEAD Schemes"
January 2024, our paper is accepted to TCHES 2024
- "Gleeok: A Family of Low-Latency PRFs and its Applications to Authenticated Encryption"

My research interest is

Whitebox Cryptography
Design of Lightweight/Low Energy/Low-Latency Ciphers
Cryptanalysis of Symmetric-Key Cryptography
Security Analysis of Real-world Products and System
End-to-End Encryption

I am a designer of

Lightweight block cipher: Piccolo, WARP
Lightweight stream cipher: LILLE, Atom
Low energy block cipher: Midori
Low Latency PRF: Orthros, Gleeok
Whitebox-secure block ciphers: SPACE, SPNbox, Galaxy, Yoroi
High throughput cipher for 6G: Rocca [Article (English)][Article (Chinese)], Areion, Rocca-S, AETHER
Wide block cipher: Ghidle, Asura

Program Committee : ASIACRYPT 2025, IWSEC 2025, EUROCRYPT 2025, IWSEC2024, ASIACRYPT 2024, SAC 2024, INDOCRYPT 2024, FSE2025/ToSC2024, INDOCRYPT 2023, SAC 2023, FSE2023/ToSC2022, ASIACRYPT2022, INDOCRYPTO2022 (Program Co-Chair), IWSEC2022, FSE2022/ToSC2021, CT-RSA2021, ASIACRYPT 2020, FSE2021/ToSC2020, ASIACRYPT 2019, INDOCRYPT 2019, FSE2020/ToSC2019, SAC2019, INDOCRYPTO2018, ASIACRYPT 2018, FSE2019/ToSC2018, FSE 2016, INDOCRYPT 2016

Reviewer: CRYPTO, EUROCRYPT, ASIACRYPT, FSE, CHES, SAC, CT-RSA, ACISP, INDOCRYPT , etc.

DBLP, Google Scholar, Research Map

[Selected Publication (IACR Publication and CCS )]

Hayato Kimura, Ryoma Ito, Kazuhiko Minematsu, Shogo Shiraki and Takanori Isobe, "Not in The Prophecies: Practical Attacks on Nostr" IEEE Euro S&P 2025.
Mostafizar Rahman,Samir Kundu and Takanori Isobe, "On the Key-Commitment Properties of Forkcipher-based AEADs", IACR Communications in Cryptology, 2025 (to appear).
Subhadeep Banik, Andrea Caforio, Tatsuya Ishikawa,Takanori Isobe, Mostafizar Rahman and Kosei Sakamoto "AETHER: An Ultra-High Throughput and Low Energy Authenticated Encryption Scheme", IACR Transactions on Cryptographic Hardware and Embedded Systems (TCHES 2025), 2025.
Kodai Taiyama, Kosei Sakamoto, Ryoma Ito, Kazuma Taka and Takanori Isobe, "Key Collisions on AES and Its Applications", ASIACRYPT 2024.
Patrick Derbez, Pierre-Alain Fouque, Takanori Isobe, Mostafizar Rahman, André Schrottenloher, "Key Committing Attacks against AES-based AEAD Schemes", IACR Trans. Symmetric Cryptol (ToSC/FSE), 2024.
Ravi Anand, Subhadeep Banik, Andrea Caforio, Tatsuya Ishikawa,Takanori Isobe, Fukang Liu, Kazuhiko Minematsu, Mostafizar Rahman,Kosei Sakamoto "Gleeok: A Family of Low-Latency PRFs and its Applications to Authenticated Encryption"IACR Transactions on Cryptographic Hardware and Embedded Systems(TCHES 2023), 2024.
Ravi Anand, Subhadeep Banik, Andrea Caforio, Kazuhide Fukushima, Takanori Isobe, Shisaku Kiyomoto, Fukang Liu, Yuto Nakano, Kosei Sakamoto and Nobuyuki Takeuchi. "An Ultra-High Throughput AES-based Authenticated Encryption Scheme for 6G: Design and Implementation", ESORICS 2023.
Fukang Liu, Lorenzo Grassi, Clémence Bouvier, Willi Meier, Takanori Isobe, "Coefficient Grouping for Complex Affine Layers", CRYPTO 2023
Fukang Liu, Ravi Anand, Libo Wang, Willi Meier, Takanori Isobe, "Coefficient Grouping: Breaking Chaghri and More", EUROCRYPT 2023.
Fukang Liu, Gaoli Wang, Santanu Sarkar, Ravi Anand, Willi Meier, Yingxin Li, Takanori Isobe, "Analysis of RIPEMD-160: New Collision Attacks and Finding Characteristics with MILP", EUROCRYPT 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", TCHES 2023.
Akinori Hosoyamada, Takanori Isobe, Kan Yasuda, Yosuke Todo, “A Modular Approach to the Incompressibility of Block-Cipher-Based AEADs”, ASIACRYPT 2022.
Fukang Liu, Santanu Sarkar, Gaoli Wang, Willi Meier and Takanori Isobe, “Algebraic Meet-in-the-Middle Attack on LowMC ”, ASIACRYPT 2022.
Fukang Liu, Santanu Sarkar, Willi Meier and Takanori Isobe, "New Low-Memory Algebraic Attacks on LowMC in the Picnic Setting", IACR Trans. Symmetric Cryptol (ToSC/FSE), 2022, issue 3, pages xx-xx, 2022.
Yosuke Todo and Takanori Isobe, "Hybrid Code Lifting on Space-Hard Block Ciphers" IACR Trans. Symmetric Cryptol (ToSC/FSE), 2022, issue 3, pages xx-xx, 2022.
Fukang Liu, Willi Meier, Santanu Sarkar, Gaoli Wang, Ryoma Ito, Takanori Isobe, "New Cryptanalysis of ZUC-256 Initialization Using Modular Differences" ,IACR Trans. Symmetric Cryptol (ToSC/FSE), 2022, issue 3, pages xx-xx, 2022.
Fukang Liu, Santanu Sarkar, Willi Meier and Takanori Isobe, "The Inverse of χ and Its Applications to Rasta-like Ciphers", Journal of Cryptology, 2022.
Andrea Caforio, Subhadeep Banik, Yosuke Todo, Willi Meier, Takanori Isobe, Fukang Liu and Bin Zhang, "Perfect Trees: Designing Energy-Optimal Symmetric Encryption Primitives", IACR Trans. Symmetric Cryptol (ToSC/FSE), 2021, issue 4, 2021.
Fukang Liu, Santanu Sarkar, Willi Meier and Takanori Isobe, "Algebraic Attacks on Rasta and Dasta Using Low-Degree Equations", ASIACRYPT 2021.
Takanori Isobe, Ryoma Ito and Kazuhiko Minematsu, "Security Analysis of SFrame", ESORICS 2021.
Yuji Koike and Takanori Isobe, "Yoroi: Updatable Whitebox Cryptography", IACR Transactions on Cryptographic Hardware and Embedded Sytems (TCHES), 2021.
Fukang Liu, Takanori Isobe, Willi Meier, "Cryptanalysis of Full LowMC and LowMC-M with Algebraic Techniques" CRYPTO 2021.
Kosei Sakamoto, Fukang Liu, Yuto Nakano, Shinsaku Kiyomoto and Takanori Isobe, "Rocca: An Efficient AES-based Encryption Scheme for Beyond 5G", IACR Trans. Symmetric Cryptol (ToSC/FSE), 2021, issue 2, 2021.
Fukang Liu, Takanori Isobe, Willi Meier and Kosei Sakamoto, "Weak Keys in Reduced AEGIS and Tiaoxin", IACR Trans. Symmetric Cryptol (ToSC/FSE), 2021, issue 2, 2021(Best Paper Award).
Subhadeep Banik, Andrea Caforio, Takanori Isobe, Fukang Liu, Willi Meier, Kosei Sakamoto and Santanu Sarkar, "Atom: A Stream Cipher with Double Key Filter", IACR Trans. Symmetric Cryptol (ToSC/FSE), 2021, issue 1, 2021.
Fukang Liu, Takanori Isobe and Willi Meier, "Exploiting Weak Diffusion of Gimli: Improved Distinguishers and Preimage Attacks", IACR Trans. Symmetric Cryptol (ToSC/FSE), 2021, issue 1, 2021.
Subhadeep Banik, Takanori Isobe, Fukang Liu, Kazuhiko Minematsu and Kosei Sakamoto, "Orthros: A Low-Latency PRF", IACR Trans. Symmetric Cryptol (ToSC/FSE), 2021, issue 1, 2021.
Fukang Liu, Takanori Isobe and Willi Meier, "Automatic Verification of Differential Characteristics:Application to Reduced Gimli", CRYPTO 2020.
Fukang Liu, Takanori Isobe and Willi Meier, "Cube-based Cryptanalysis of Subterranean-SAE" , IACR Trans. Symmetric Cryptol (ToSC/FSE) 2020.
Subhadeep Banik, Khashayar Barooti and Takanori Isobe, "Cryptanalysis of Plantlet ", IACR Trans. Symmetric Cryptol (ToSC/FSE) 2020.
Fukang Liu, Christoph Dobraunig, Florian Mendel, Takanori Isobe , Gaoli Wang and Zhenfu Cao, "New Semi-Free-Start Collision Attack Framework for Reduced RIPEMD-160 ", IACR Trans. Symmetric Cryptol (ToSC/FSE) 2020.
Fukang Liu, Christoph Dobraunig, Florian Mendel, Takanori Isobe, Gaoli Wang and Zhenfu Cao, "Efficient Collision Attack Frameworks for RIPEMD-160", CRYPTO 2019.
Takanori Isobe and Kazuhiko Minematsu, "Breaking the Message Integrity of End-to-End Encryption Schemes of LINE", ESORICS 2018.
Yosuke Todo, Takanori Isobe, Willi Meier, Kazumaro Aoki, and Bin Zhang, "Fast Correlation Attack Revisited --Cryptanalysis on Full Grain-128a, Grain-128, and Grain-v1", CRYPTO 2018.
Qingju Wang, Yonglin Hao, Yosuke Todo, Chaoyun Li, Takanori Isobe, Willi Meier, "Improved Division Property Based Cube Attacks Exploiting Algebraic Properties of Superpoly", CRYPTO 2018.
Gianira N. Alfarano,Christof Beierle, Takanori Isobe, Stefan Kölbl, Gregor Leander, "ShiftRows Alternatives for AES-like Ciphers and Optimal Cell Permutations for Midori and Skinny", ToSC/FSE 2019.
Subhapeep, Banik, Vasily Mikhalev, Frederik Armknecht, Takanori Isobe, Willi Meier, Andrey Bogdanov, Yuhei Watanabe, Francesco Regazzoni, "Toward Low Energy Stream Ciphers", ToSC/FSE 2019.
Subhadeep Banik, Takanori Isobe, Tingting Cui and Jian Guo , “Some cryptanalytic results on Lizard ”, ToSC/FSE 2018.
Takanori Isobe and Kyoji Shibutani, "New Key Recovery Attacks on Minimal Two-Round Even-Mansour Ciphers", ASIACRYPT 2017.
Yosuke Todo, Takanori Isobe, Yonglin Hao, and Willi Meier, "Cube Attacks on Non-Blackbox Polynomials Based on Division Property", CRYPTO 2017.
Subhadeep Banik, Andrey Bogdanov, Takanori Isobe and Martin Bjerregard jepsen. “Analysis of Software Countermeasures for Whitebox Encryption.” ToSC/FSE 2017.
Andrey Bogdanov , Takanori Isobe and Elmar Tischhauser, “Towards Practical Whitebox Cryptography: Optimizing Efficiency and Space Hardness”, ASIACRYPT 2016.
Subhadeep Banik and Takanori Isobe, " Cryptanalysis of the Full Spritz Stream Cipher”, FSE 2016.
Andrey Bogdanov and Takanori Isobe, “White-Box Cryptography Revisited: Space-Hard Ciphers”, ACM Conference on Computer and Communications Security (CCS) 2015.
Subhadeep Banik, Andrey Bogdanov, Takanori Isobe, Kyoji Shibutani, Harunaga Hiwatari, Toru Akishita, Francesco Regazzoni, “Midori: A Block Cipher for Low Energy”, ASIACRYPT 2015.
Andrey Bogdanov and Takanori Isobe, “How Secure is AES Under Leakage”, ASIACRYPT 2015..
Takanori Isobe and Kyoji Shibutani, " Improved All-Subkeys Recovery Attacks on FOX, KATAN and SHACAL-2 Block cipher”, FSE 2014.
Takanori Isobe, "A Single Key Attack on the Full GOST Block Cipher", Journal of Cryptology, 2013.
Takanori Isobe and Kyoji Shibutani, "Generic Key Recovery Attack on Feistel Scheme”, ASIACRYPT 2013.
Takanori Isobe, Toshihiro Ohigashi, Yuhei, Watanabe and Masakatu Morii, "Full Plaintext Recovery Attack on Broadcast RC4”, FSE 2013.
Li Ji, Takanori Isobe and Kyoji Shibutani, "Converting Meet-in-the-Middle Preimage Attack into Pseudo Collision Attack: Application to SHA-2”, FSE 2012.
Kyoji Shibutani, Takanori Isobe, Harunaga Hiwatari, Atsushi Mitsuda, Toru Akishita and Taizo Shirai, "Piccolo : A Ultra-Lightweight Blockcipher" CHES 2011.
Takanori Isobe, "A Single Key Attack on the Full GOST Block Cipher", FSE 2011 (Best Paper Award).
Takanori Isobe and Kyoji Shibutani, "Preimage Attack on Reduced Tiger and SHA-2”, FSE 2009 .

Contact: takanori.isobe(at)ist(dot)osaka-u(dot)ac(dot)jp