Wonseok Choi

Wonseok Choi

Assistant Professor, Cryptographer

Wonseok’s Homepage

I am Wonseok Choi (최원석, 崔元碩), an assistant professor in the EECS department at DGIST, Korea.

My research interests include cryptography (e.g., symmetric-key, public-key, MPC, quantum, and post-quantum) and related topics in cryptology and mathematics. I aim to establish precise security models or requirements for each problem, define appropriate notions, and conduct thorough analyses.

I was a postdoc at Purdue University and Georgia Tech, working with Vassilis Zikas. My postdoctoral research focused on Byzantine fault-tolerant protocols and on applications of cryptography, such as digital signatures for e-voting and blockchain. I also worked (and am still working) on optimizing/improving messaging protocols using symmetric-key encryption and on definitional issues in anamorphic encryption. Before that, I was a research fellow at KIAS, where I worked on symmetric-key cryptography and provable security methodologies, mentored by Changmin Lee.

I received my Ph.D. from KAIST, where I was advised by Jooyoung Lee. During my Ph.D., I focused on provable security in symmetric-key cryptography. My thesis was titled “Study on Building Pseudorandom Functions from Cryptographic Primitives.”

I am currently running the Cryptology and Information Security Lab at DGIST. Our research focuses on:

  1. Security analysis and proofs of cryptographic algorithms and protocols; and

  2. Designing algorithms and protocols for multi-party computation, blockchain, and related areas.

We were recently awarded the Outstanding Young Scientist Grant from the NRF (Korean government)! See the latest news!

Updated: I sincerely apologize to the applicants who have sent phd/postdoc position inquiries; due to the volume of emails, I couldn’t reply to all of them.

Latest News

(Mar. 2026) I will give an invited talk at ASK 2026 and attend FSE 2026. Updated: We, GAPS organizers, were awarded the most chewing gum-ish talk prize during the FSE 2026 rump session!

(Mar. 2026) I was awarded the Outstanding Young Scientist Grant to develop a unified framework for the concrete security of MPC.

(Jul. 2025) Our paper on sharp anonymous multisignatures, co-authored with Xiangyu and Vassilis, was accepted at AFT 2025.

(Jul. 2025) I am visiting Ruhr-University of Bochum for a month, hosted by Ashwin Jha and Gregor Leander.

(May 2025) I became an assistant professor at DGIST and started running the Cryptology and Information Security Lab.

(Apr. 2025) Our paper on designing new AEADs dedicated to short input lengths was accepted at TCHES2025(3)/CHES2025.

Professional Activities

Organizer

Program Committee

  • FSE 2024-2027
  • ISC 2024-2025
  • ASIACRYPT 2024

Talks

  • “On Reduced Key Spaces of Even-Mansour Ciphers”
    Invited Talk at ASK 2026, Singapore, Mar. 2026.

  • “Cymric: Short-tailed but Mighty”
    CHES 2025, Malaysia (Kuala Lumpur), Sep. 2025.
    Invited Talk at 2025 GAPS Workshop, Singapore, Sep. 2025.

  • “On Overidealizing Ideal Worlds: Xor of Two Permutations and its Applications”
    Invited Talk at Radbound University, Nijmegen (the Netherlands), Mar. 2024.
    Invited Talk at DESILO, Seoul (Korea), Dec. 2023.
    Invited Talk at ASK 2023, Guangzhou (China), Dec. 2023.

  • “Improved Multi-User Security Using the Squared-Ratio Method”
    CRYPTO 2023, Santa Barbara (CA), Aug. 2023.
    Athecrypt 2023, Athens (Greece), May. 2023.
    Invited Talk at NEC Core Technology Forum, Kanagawa (Japan), Dec. 2022.

  • “Multi-User Security of the Sum of Truncated Random Permutations”
    ASIACRYPT 2022, Taipei (Taiwan), Dec. 2022.
    2022 Global KMS International Conference, Seoul (Korea), Oct. 2022.

  • “Building PRFs from TPRPs: Beyond the Block and the Tweak Length Bounds”
    FSE 2024, Leuven (Belgium), Mar. 2024.
    2022 KMS Spring Meeting, Online, Apr. 2022.
    Security@KAIST Student Research Presentation, Online, Nov. 2021.
    National Cryptography Contest Awards, Seoul (Korea), Oct. 2021.

  • “Indifferentiability of Truncated Random Permutations”
    ASIACRYPT 2019, Kobe (Japan), Dec. 2019.
    Invited Talk at Korea Cryptography Forum Workshop, Gyeonggi (Korea), May. 2019.
    National Cryptography Contest Awards, Seoul (Korea), Nov. 2018.

Teaching and Advising

Courses

  • DGIST CSE405 Computer Security (2026 Spring)
  • DGIST CSE301 Computer Algorithms (2025 Fall)

PhD Students

  • Wookjin Choi (Starting in Fall 2026)

Publication List

  • Wonseok Choi, Xiangyu Liu, and Vassilis Zikas, “Blockchain Governance via Sharp Anonymous Multisignatures”, AFT 2025.

  • Alexandre Adomnicăi, Wonseok Choi, Yeongmin Lee, Yusuke Naito, and Kazuhiko Minematsu, “Cymric: Short-tailed but Mighty”, TCHES 2025(3)/CHES 2025.

  • Wonseok Choi, Jooyoung Lee, and Yeongmin Lee, “Tight Security of Double-Block Nonce-Based MACs”, ASIACRYPT 2024.

  • Ritam Bhaumik, Wonseok Choi, Avijit Dutta, Cuauhtemoc Mancillas Lopez, Hrithik Nandi, and Yaobin Shen, “Efficient Variants of TNT with BBB Security”, ProvSec 2024.

  • Wonseok Choi, Seongha Hwang, Byeonghak Lee, and Jooyoung Lee, “ZLR: A Fast Online Authenticated Encryption Achieving Full Security”, DCC 2024.

  • Ritam Bhaumik, Bishwajit Chakraborty, Wonseok Choi, Avijit Dutta, Jérôme Govinden, and Yaobin Shen, “The Committing Security of MACs with Applications to Generic Composition”, CRYPTO 2024.

  • Wonseok Choi, Jooyoung Lee, and Yeongmin Lee, “Building PRFs from TPRPs: Beyond the Block and the Tweak Length Bounds”, ToSC 2024(1) / FSE 2024.

  • Yu Long Chen, Wonseok Choi, and Changmin Lee, “Improved Multi-User Security Using the Squared-Ratio Method”, CRYPTO 2023.

  • Wonseok Choi, Hwigyeom Kim, Jooyoung Lee, and Yeongmin Lee, “Multi-User Security of the Sum of Truncated Random Permutations”, ASIACRYPT 2022.

  • Wonseok Choi, Byeonghak Lee, Jooyoung Lee, and Yeongmin Lee, “Toward a Fully Secure Authenticated Encryption Scheme From a Pseudorandom Permutation”, ASIACRYPT 2021.

  • Wonseok Choi, Akiko Inoue, Byeonghak Lee, Jooyoung Lee, Eik List, Kazuhiko Minematsu, and Yusuke Naito, “Highly Secure Nonce-based Macs from the Sum of Tweakable Block Ciphers”, ToSC 2020(4) / FSE 2022.

  • Wonseok Choi, Byeonghak Lee, Yeongmin Lee, and Jooyoung Lee, “Improved Security Analysis for Nonce-based Enhanced Hash-then-Mask MACs”, ASIACRYPT 2020.

  • Jincheol Ha, Seongkwang Kim, Wonseok Choi, Jooyoung Lee, Dukjae Moon, Hyojin Yoon, and Jihoon Cho, “Masta: An HE-friendly Cipher Using Modular Arithmetic”, IEEE Access 2020.

  • Wonseok Choi, Byeonghak Lee, and Jooyoung Lee, “Indifferentiability of Truncated Random Permutations”, ASIACRYPT 2019.

Last Update: 26/MAR/2026