Ryo Ohashi

dblp:129/6141 · DBLP profile ↗

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5ranked-venue papers

3as first author

5since 2021 · last 2026

0000-0001-6809-7767ORCID · corroborated

Security and privacy · 3 · 2 first-author · 3 since 2021Theory of computation · 2 · 1 first-author · 2 since 2021

Year	Publication	Venue	Position
2026	A Collision Attack on the LTZ Hash Function Based on a Conjecture on Supersingular Non-superspecial Isogeny Graphs of Dimension 2 Ryo Ohashi, Hiroshi Onuki	PQCrypto (2)	1
2026	Superspecial genus-4 double covers of elliptic curves abstract In this paper we study genus-4 curves obtained as double covers of elliptic curves. Firstly we shall give explicit defining equations of such curves with explicit criterion for whether it is nonsingular, and show the irreducibility of the long polynomial determining whether the genus-4 curve is nonsingular or not, in any characteristic ≠ 2 , 3 . Secondly, as an application, we enumerate superspecial genus-4 double covers of elliptic curves in small characteristic. Takumi Ogasawara, Ryo Ohashi, Kosuke Sakata, Shushi Harashita	J. Symb. Comput.	2
2025	An Efficient Collision Attack on Castryck-Decru-Smith's Hash Function Ryo Ohashi, Hiroshi Onuki	PQCrypto (2)	1
2025	Efficient Theta-Based Algorithms for Computing (ℓ , ℓ )-Isogenies on Kummer Surfaces for Arbitrary Odd ℓ Ryo Yoshizumi, Hiroshi Onuki, Ryo Ohashi, Momonari Kudo, Koji Nuida	PQCrypto (2)	3
2022	Fast Enumeration of Superspecial Hyperelliptic Curves of Genus 4 with Automorphism Group V4 Ryo Ohashi, Momonari Kudo, Shushi Harashita	WAIFI	1