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Akinori Hosoyamada(細山田 光倫)

I am a researcher of cryptography at NTT Social Informatics Laboratories, NTT Corporation, Japan.

Contact e-mail address: akinori dot hosoyamada at protonmail dot com

Last update: September 30, 2021

Research Interests and Highlights

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 collision attacks on concrete hash functions [HS20,HS21].
  • Quantum multicollision-finding algorithms for cryptographic hash functions [HSX17,HSTX19,HSTX20].
  • Quantum attack that takes advantage of Simon’s algorithm without quantum superposed queries to keyed oracles [BHNSS19].
  • (Post-)quantum security proofs of symmetric-key schemes, e.g., a qPRP security proof of the 4-round Luby-Rackoff (Feistel) construction [HY18,HI19,HI21a,HI21c].

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.)


Job Experience

2016.04 – present

Researcher, NTT Corporation. (NTT Secure Platform Laboratories -> NTT Social Informatics Laboratories)


2018.10 – 2021.09

Doctor of Engineering from Nagoya University. (Supervisor: Tetsu Iwata / Doctoral Thesis: “Post-Quantum Provable Security in Symmetric-Key Cryptography”)

2014.04 – 2016.03

Master of Science from Kyoto University. (Major: Algebraic/Differential Topology)

2010.04 – 2014.03

Bachelor of Science from Kyoto University. (Major: 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].


  • [HI21b] Hosoyamada, A., Iwata, T.: Indifferentiability of SKINNY-HASH Internal Functions. Accepted to IEICE Trans. Fundam. Electron. Commun. Comput. Sci. ([ePrint])
  • [HI21c] Hosoyamada, A., Iwata, T.: Provably Quantum-Secure Tweakable Block Ciphers. IACR Trans. Symmetric Cryptol. 2021(1): 337-377 (2021) [Link] ([ePrint])
  • [HNS20] Hosoyamada, A., Naya-Plasencia, M., Sasaki, Y.: Improved Attacks on sLiSCP Permutation and Tight Bound of Limited Birthday Distinguishers. IACR Trans. Symmetric Cryptol. 2020(4): 81-118 (2019) [Link]([ePrint])
  • [HSTX20] Hosoyamada, A., Sasaki, Y., Tani, S., Xagawa, K.: Quantum algorithm for the multicollision problem. Theor. Comput. Sci. 842: 100-117 (2020) [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 Trans. Fundam. Electron. Commun. Comput. Sci. 102-A(1), 27-34 (2019) [Link] (Note: A preliminary version of this paper appeared at IWSEC 2017 [HA17].)


Other Activities

Program Committee Member

  • Asiacrypt 2021, December 5-9, 2021, Singapore
  • IWSEC 2021, September 8-10, 2021, Virtual

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)



Asiacrypt 2020 Best Paper Award.


SCIS 2018 Paper Award.


IWSEC 2017 Best Paper Award.