sean9892

I’m Yubin Choi(최유빈), and an undergraduate student at KAIST.

Currently I’m serving in ROK Air Force (2024.02.13-2025.11.12).

Education

  • KAIST
    • B.S. in School of Computing (2022-Current)
  • Chungbuk Science High School
    • an year early graduated (2020-2021)

Competitions and Awards

  • Security Competitions (CTFs)
    • Whitehat Contest 2024 Soldier’s Division 1st place - Team 키보드워리어플랫폼
    • 2024 공군 정보통신경연대회 2nd place
    • 2024 국방사이버보안경진대회 3rd place - Team 공CERT군
    • 2024 공군사이버전사경연대회 3rd place
    • Whitehat Contest 2024 General Division 4th place - Team KAIST GoN
    • 2022 Crypto Analysis Contest 1st place - Team KAIST GoN
    • HackTheon Sejong 2022 4th place - Team KaisTheon

Portfolio

  • Published Crypto Challenges to Dreamhack (2021-Current)
    • Elliptic Power of CRC: Revenge Challenge of Power of CRC; zeroing out CRC value over hidden finite field without solving discrete logarithm
  • Challenge Author for KAIST GoN Qual (2023-Current)
    • Verhältnis: Solving HNP-2H to recover two small integers from their 2-hole masked ratio over the given finite field
    • Hoshimachi: LFSR output prediction without solving for full states
    • Double Linear: seed recovery on LFSR which adopts AES with a linear s-box as a filter function
    • Is it CRT-RSA?: Factoring two RSA moduli with general solution for linear diophantine equation
  • Challenge Author for HSPACE Belluminar CTF (2024)
    • BabyHash: topological sort to combine inversed hash values with rainbow-table attack on small plaintext space
  • Student Instructor at KAIST (2022-2023)
    • Humanity/Leadership III <Hacking School>

Extracurricular activities

  • Member of Cryptology Wargame Website CryptoHack (2020-Current)
    • Solved 233/233 regular challenges, 41st 100%-cleared