Hiroyuki Katsura (桂 宏行)

I’m Hiroyuki Katsura, 3rd-year PhD student, supervised by Naoki Kobayashi in 3-year PhD course at Dept. of Computer Science, Graduate School of Information Science and Technology of The University of Tokyo.

Contacts

• Email:
  • University: katsura[at]kb.is.s.u-tokyo.ac.jp
  • Gmail: moratorium08[at]gmail.com
• GitHub: moratorium08
• Linkedin

Research Interests

My main research interest is to propose analyses to enhance software reliability. This includes:

• (Automated) Software verification
  • Logic-based automated software verification (c.f. CHC solving)
  • Refinement types
• Software security
  • Fuzzing

Publications

• Hiroyuki Katsura, Naoki Kobayashi, Ken Sakayori, and Ryosuke Sato. Mode-based Reduction from Validity Checking of Fixpoint Logic Formulas to Test-Friendly Reachability Problem. APLAS 2024.
• Hiroyuki Katsura, Naoki Kobayashi, Ken Sakayori, and Ryosuke Sato. Mode-based Transformation from Satisfiability of Constrained Horn Clauses to Test-friendly Reachability Problem. HCVS 2024.
• Hiroyuki Katsura, Naoki Kobayashi, and Ryosuke Sato. Higher-Order Property-Directed Reachability. ICFP 2023. [video]
• Yuki Koike, Hiroyuki Katsura, Hiromu Yakura, and Yuma Kurogome: SLOPT: Bandit Optimization Framework for Mutation-Based Fuzzing, ACSAC 2022.
• Kazuyuki Asada, Hiroyuki Katsura, and Naoki Kobayashi. On Higher-Order Reachability Games Vs May Reachability. RP 2022.
• Hiroyuki Katsura, Naoki Iwayama, Naoki Kobayashi, and Takeshi Tsukada. A New Refinement Type System for Automated νHFLZ Validity Checking. APLAS 2020.

Education

• Apr 2022 - Now: Doctor of Information Science Kobayashi Lab
• Apr 2020 - Mar 2022: Master of Information Science Kobayashi Lab, Dept. of Computer Science, Grad School of IST, UTokyo
• Apr 2016 - Mar 2020: Bachelor of Science, Dept. of Information Science, School of Science, UTokyo

Experience

Grants

• JSPS (学振) Research Fellowship for Young Scientists DC2, Apr 2023 - Mar 2025 高階プログラム自動検証のさらなる発展と自動テストへの融合 (Developing Automated Higher-order Program Verification and Combination with Automated Testing): project detail(ja)

Internships

• Feb 2021 - Aug 2022: Ricerca Security, Tokyo
  • Studied fuzzing with reinforcement learning
• Aug - Sep 2020: LINE corp, Tokyo
  • Developed an automated update for hypervisors on OpenStack using Kubernetes Operator Pattern (blog post[ja]).
• Aug 2017 - Jul 2018: Flatt Inc, Tokyo
  • Developed a backend infrastructure for a live commerce app
  • Designed a scalable live streaming infrastructure using GCP
• Sep 2016 - Oct 2017: Unipro Inc, Tokyo
  • Researched translation systems from natural language to “datastore representation” for knowledge.

Teaching Assistants

I have been a teaching assistant three times at Dept. of Information Science, School of Science, The University of Tokyo.

• Sep 2022 - Feb 2023: Processor and Compiler Lab
• Apr 2023 - Aug 2023: Functional and Logic Programming Lab
• Sep 2020 - Feb 2021: Processor and Compiler Lab

Projects

• Google Summer of Code, Libvirt organization as a Participant Mar - Aug 2019
  • Developed Rust bindings for libguestfs, which provides a set of tools for manipulating and communicating with virtual machine disk images (archive).
• osmium: an operating system written in Rust which runs on RISC-V
  • Developed an operating system on RISC-V from scratch using Rust (article(ja), translated one by cb372).
  • Repo: https://github.com/moratorium08/osmium (Stars +190)

CTF (Capture The Flag; Software Security Competition)

I have been playing CTFs as a member of an university team TSG whose team members are all from The University of Tokyo. Sometimes, I join in larger teams to compete large contests like DEFCON. I mainly play pwnable (binary exploit) and reversing.

Here are some of my achievements in CTF contests. Note that due to the collaborative nature of CTFs, my individual contribution varied from one CTF to another :)

• As a member of TSG
  • SECCON 2022: International Finalists
  • CTFZone 2020: Finalists
  • TokyoWesterns CTF 2020: 9th
  • Codeblue CTF 2018: Finalists
  • SECCON 2018 International Finals: Winner
• As a member of other teams
  • DEFCON CTF 2024 Qualifier 11th as a member of undef1ned
  • SECCON CTF Domestic Finals 2023: winner as a member of :)
  • DEFCON CTF 2023: finalists as a member of undef1ned
  • DEFCON CTF 2022: finalists as a member of ./V /home/r/.bin/tw
  • Google CTF 2020(hackceler8): finalists as a member of I use bing

My CTF Challenges

I have created a lot of CTF challenges so far from easy one to harder one: please refer to this page　(TBD).

My favorite ones are

• chat (pwnable) TSG CTF 2021
• Catastrophe (pwnable) TSG CTF 2021
• seccon tree (pwnable) SECCON CTF 2021

Random collection of my writeups of my challenges:

• bypy @ TSG CTF 2023
• sloader @TSG CTF 2023
• 👻 @TSG CTF 2023
• Conduit @TSG CTF 2023
• seccon_tree @SECCON CTF 2021
• dis-me @SECCON CTF 2021
• cHeap @TSG CTF 2021
• Catastrophe @TSG CTF 2021
• chat @TSG CTF 2021, co-authored with azaika
• Cling @TSG CTF 2021
• Coffee @TSG CTF 2021
• Yet Another PySandbox @SECCON CTF 2020
• Yet^2 Another PySandbox @SECCON CTF 2020
• mlml@SECCON CTF 2020
• Fixer@SECCON CTF 2020

Other Activities

ISUCON

ISUCON is a Japanese contest held by LINE corp, where participants aim to fine-tune a given web service within set regulations. I have played ISUCON six times as a member of FetchDecodeExecWrite.

• ISUCON 13 5th
• ISUCON 12 5th
• ISUCON 11 3rd
• ISUCON 10 6th
• ISUCON 9 finalists
• ISUCON 8 finalists

Security Camp

• Global Cybersecurity Camp 2021
• Security Camp 2013

Hobbies

Apart from researching, I’m a big fan of

• Capture The Flag (security competition), especially pwnable
• Low-level programming
• Brewing drip coffee “nicely”
• Bouldering / Climbing
• Board games