Akinori Hosoyamada(細山田 光倫)

I am a researcher of cryptography at NTT Secure Platform Laboratories, NTT Corporation, Japan. I am also a doctoral course student at Nagoya University, supervised by Prof. Tetsu Iwata.

Contact e-mail adress: hosoyamada dot akinori at nagoya-u dot jp

Last update: September 25th, 2020

Research Interests and Hilights

Currently I am interested in symmetric-key cryptography, especially in post-quantum security of symmetric-key schemes, e.g., cryptanalysis of block ciphers and hash functions using quantum algorithms, and post-quantum security proofs for mode of operations. The following list is the highlight of my recent results with co-researchers.

  • Impossibility of quantum fully-black-box reductions from collision-resistant hash functions to one-way permutations [HY20] (Best Paper Award @ Asiacrypt 2020).
  • Dedicated quantum colilsion attacks on concrete hash functions [HS20].
  • Quantum multicollision-finding algorithms for cryptgraphic hash functions [HSX17,HSTX19,HSTX20].
  • Proof that the 4-round Luby-Rackoff construction (Feistel construction) is a quantum pseudo-random permutation [HI19].
  • Quantum attack that takes advantage of Simon’s algorithm without quantum superposed queries to keyed oracles [BHNSS19].
  • Proof for one-wayness of the combination of the Merkle-Damgaard construction with the Davies-Meyer construction against quantum adversaries [HY18].

So far most of my published results are related to post-quantum security of symmetric-key schemes, but I am also interested in other topics on cryptography both in the quantum and classical settings. (Basically I like pure/applied mathematics.)

Papers (in English)

See also dblp

Peer-Reviewed International Conference (with proceedings)

Peer-Reviewed International Conference (without proceedings)

  • [BHNSS20] Bonnetain, X., Hosoyamada, A., Naya-Plasencia, M., Sasaki, Y., Schrottenloher, A.: Quantum Attacks without Superposition Queries: the Offline Simon’s Algorithm. (QIP 2020, single-session talk) See also [BHNSS19].


  • [HSTX20] Hosoyamada, A., Sasaki, Y., Tani, S., Xagawa, K.: Quantum algorithm for the multicollision problem. To appear on Theoretical Computer Science. [Link] (Note: Preliminary versions of this paper appeared at ASIACRYPT 2017 [HSX17] and PQCrypto 2019 [HSTX20].)
  • [HA19] Hosoyamada, A., Aoki, K.: On Quantum Related-Key Attacks on Iterated Even-Mansour Ciphers. IEICE Transactions 102-A(1), 27-34 (2019) [Link] (Note: A preliminary version of this paper appeared at IWSEC 2017 [HA17].)


  • [HNS20] Hosoyamada, A., Naya-Plasencia, M., Sasaki, Y.: Improved Attacks on sLiSCP Permutation and Tight Bound of Limited Birthday Distinguishers IACR Cryptology ePrint Archive 2020/1089 (2020) [Link]
  • [CHLS20] Cid, C., Hosoyamada, A., Liu, Y., Sim, S.: Quantum Cryptanalysis on Contracting Feistel Structures and Observation on Related-key settings. IACR Cryptology ePrint Archive 2020/959 (2020) [Link] (Note: This paper’s results are obtained in a discussion group of ASK 2019.)

Other Activities

Invited Seminar


Dagstuhl Seminar 19421, Quantum Cryptanalysis, October 13 – 18, 2019, Schloss Dagstuhl, Wadern, Germany [Link]

Invited Talk (International)


The 9th Asian-workshop on symmetric key cryptography, December 13 – 15, 2019, University of Hyogo, Kobe, Japan [Link]



[H20] Hosoyamada, A.: Review and Evaluation of the Effect of Quantum Computers on the Security of Symmetric-Key Cryptographic Schemes. CRYPTREC Investigation Reports on Cryptographic Techniques in FY 2019. [Link] (in Japanese)


2020.12 (planned)

Asiacrypt 2020 Best Paper Award.


SCIS 2018 Paper Award.


IWSEC 2017 Best Paper Award.


Job Experience

2016.04 – present

Researcher, NTT Secure Platform Laboratories, NTT Corporation.


2018.10 – present

Doctoral course student in the Department of Information and Communication Engineering, Nagoya University.

2014.04 – 2016.03

M. Sc. from Kyoto University. (Major: Algebraic/Differential Topology)

2010.04 – 2014.03

B. Sc. from Kyoto University. (Major: Mathematics)

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