Ziyi Guan

Ziyi Guan

I am a fifth-year Ph.D. student at the EPFL theory group, where I am advised by Alessandro Chiesa and Mika Göös. I received a B.S. in Computer Science and a B.S. in Mathematical Sciences from Carnegie Mellon University in 2020.

I am interested in theoretical computer science, particularly complexity theory, probabilistic proof systems, cryptography, and quantum computing.

Papers

14.
SNARGs for NP via Fiat–Shamir in the Plain Model
[ePrint]
Ziyi Guan, Eylon Yogev
13.
On the Fiat–Shamir Security of Succinct Arguments from Functional Commitments
[ePrint] [talk by Christian]
Alessandro Chiesa, Ziyi Guan, Christian Knabenhans, Zihan Yu
ZKProof 7, Sofia, Bulgaria
12.
All Polynomial Generators Preserve Distance with Mutual Correlated Agreement
[ePrint]
Sarah Bordage, Alessandro Chiesa, Ziyi Guan, Ignacio Manzur
CCC 2026 (41st Computational Complexity Conference)
ZKProof 8, Rome, Italy
11.
Quantum Rewinding for IOP-Based Succinct Arguments
[ePrint] [slides]
Alessandro Chiesa, Marcel Dall'Agnol, Zijing Di, Ziyi Guan, Nicholas Spooner
TCC 2025 (23rd Theory of Cryptography Conference)
10.
Relativized Succinct Arguments in the ROM Do Not Exist
[ePrint] [slides]
Annalisa Barbara, Alessandro Chiesa, Ziyi Guan
TCC 2025 (23rd Theory of Cryptography Conference)
ZKProof 7, Sofia, Bulgaria
9.
Breaking Verifiable Delay Functions in the Random Oracle Model
[ePrint] [slides] [slides by Artur]
Ziyi Guan, Artur Riazanov, Weiqiang Yuan
Crypto 2025 (45th Annual International Cryptology Conference)
8.
Generalised Linial-Nisan Conjecture is False for DNFs
[ECCC]
Yaroslav Alekseev, Mika Göös, Ziyi Guan, Gilbert Maystre, Artur Riazanov, Dmitry Sokolov, Weiqiang Yuan
CCC 2025 (40th Computational Complexity Conference)
7.
Untangling the Security of Kilian’s Protocol: Upper and Lower Bounds
[ePrint] [slides]
Alessandro Chiesa, Marcel Dall'Agnol, Ziyi Guan, Nicholas Spooner, Eylon Yogev
TCC 2024 (22nd Theory of Cryptography Conference)
6.
Security Bounds for Proof-Carrying Data from Straightline Extractors
[ePrint] [slides]
Alessandro Chiesa, Ziyi Guan, Shahar Samocha, Eylon Yogev
TCC 2024 (22nd Theory of Cryptography Conference)
ZKProof 7, Sofia, Bulgaria
5.
Quantum and Classical Communication Complexity of Permutation-Invariant Functions
[arXiv]
Ziyi Guan, Yunqi Huang, Penghui Yao, Zekun Ye
STACS 2024 (41st International Symposium on Theoretical Aspects of Computer Science)
IEEE Transactions on Information Theory
4.
On Parallel Repetition of PCPs
[ePrint] [slides]
Alessandro Chiesa, Ziyi Guan, Burcu Yıldız
ITCS 2024 (15th Innovations in Theoretical Computer Science)
3.
Depth-3 Circuits for Inner-Product
[ECCC] [slides]
Mika Göös, Ziyi Guan, Tiberiu Mosnoi
MFCS 2023 (48th International Symposium on Mathematical Foundations of Computer Science)
Information and Computation (invited to special issue on MFCS 2023)
2.
On the Security of Succinct Interactive Arguments from Vector Commitments
[ePrint] [slides]
1.
Linear-Time Probabilistic Proofs with Sublinear Verification for Algebraic Automata Over Every Field
[ePrint]

Talks

9.
On the Security of Succinct Arguments from Probabilistic Proofs
[slides] [abstract]
Vienna · Workshop on Zero-Knowledge, Succinct Proofs and Symmetric Cryptography · Feb 9, 2026
Boston University · Security Seminar · Sep 3, 2025
Carnegie Mellon University · CyLab Crypto Seminar · Aug 28, 2025 [video]
Aarhus University · June 26, 2025
ETH Zurich · May 19, 2025

Succinct arguments are fundamental cryptographic primitives with wide-ranging applications. A common approach to build succinct arguments is from probabilistic proofs, dating back to Kilian's protocol that combines a PCP and a Merkle tree.

In this talk, I will present the tightest bound on the regular security of Kilian's protocol and show how to obtain similar bounds for more general argument systems, such as those based on polynomial commitment schemes. I'll conclude with results that achieve post-quantum security and Fiat-Shamir security for general classes of arguments.

8.
Relativized Succinct Arguments in the ROM Do Not Exist
[slides]
Aarhus · TCC 2025 · Dec 2, 2025
EPFL · Swiss Crypto Day · Oct 31, 2025
Sofia · ZKProof 7 · Mar 24, 2025 [video]
7.
Breaking Verifiable Delay Functions in the Random Oracle Model
[slides]
New York University · Crypto & Sec Seminar· Sep 9, 2025
MIT · Cryptography and Information Security Seminar · Sep 5, 2025
Cornell University · Theory Seminar · Aug 27, 2025
UCSB · Crypto 2025 · Aug 18, 2025
Aarhus University · NordiCrypt Summer · June 30, 2025
6.
Quantum Rewinding for IOP-Based Succinct Arguments
[slides]
ENS · Paris ZK Day · June 9, 2025
University of Zurich · Workshop on post-quantum cryptography · June 3, 2025
Bocconi University · May 29, 2025
5.
Security Bounds for Proof-Carrying Data from Straightline Extractors
[slides]
Sofia · ZKProof 7 · Mar 24, 2025 [video]
Bocconi University · TCC 2024 · Dec 4, 2024
University of St.Gallen · Swiss Crypto Day · Sep 2, 2024
ETH Zurich · CrossFyre · May 25, 2024
Carnegie Mellon University · Crypto Seminar · Mar 21, 2024 [video]
4.
Untangling the Security of Kilian’s Protocol: Upper and Lower Bounds
[slides]
Bocconi University · TCC 2024 · Dec 3, 2024
3.
On the Security of Succinct Interactive Arguments from Vector Commitments
[slides]
New York University · Crypto Reading Group · February 21, 2024
King’s College London · CYS Research Seminar · February 7, 2024
Bar-Ilan University · Crypto Seminar · January 25, 2024
2.
On Parallel Repetition of PCPs
[slides]
University of Cambridge · Algorithms and Complexity Seminar · February 5, 2024
Bocconi University · Bocconi Seminar · January 24, 2024
Nanjing University · Theory Seminar · November 22, 2023
1.
Depth-3 Circuits for Inner-Product
[slides]
Bordeaux INP · MFCS 2023 · August 31, 2023

Supervising

Yuetian Wu
Peking University Undergrad
Jun 2025 – present · Summer @ EPFL
Parsa Tasbihgou
EPFL Master's
Sep 2024 – Feb 2025 · Semester Project
Sebastian Simon
Princeton University Master's
Jul 2024 – Feb 2025 · Summer @ EPFL
Mathias Marty
EPFL Master's
Nov 2023 – Jun 2024 · EPFL Master’s Thesis
› On State-Restoration Knowledge Soundness from Special Soundness
Bocconi Master's → ETHz Ph.D.
Jun 2023 – Jun 2024 · Summer @ EPFL
Keming Ouyang
UMich Undergrad
Jun 2023 – Sep 2023 · Summer @ EPFL
EPFL Master’s → EPFL Ph.D.
Mar 2023 – Feb 2025 · EPFL Master’s Thesis
› On Parallel Repetition of MIPs
Nikolaos Efthymiou
EPFL Master's
Jan 2023 – Jun 2023 · Semester Project
Zihan Yu
EPFL Master’s → Yale Ph.D.
Jan 2022 – Feb 2025 · EPFL Master’s Thesis
› On the Fiat-Shamir Security of FIOP-Based Succinct Arguments
Andrea Byku
ETHz Master's
Jan 2022 – Jun 2022 · Semester Project

Teaching

Spring 2026
Co-instructor·Theory of Computation·EPFL
Spring 2025
Head Teaching Assistant·Theory of Computation·EPFL
Spring 2024
Head Teaching Assistant·Theory of Computation·EPFL
Fall 2023
Teaching Assistant·Foundation of Probabilistic Proofs·EPFL
Summer 2023
Teaching Assistant·Foundations and Frontiers of Probabilistic Proofs·Zurich, Switzerland
Spring 2023
Teaching Assistant·Theory of Computation·EPFL
Fall 2022
Teaching Assistant·Foundation of Probabilistic Proofs·EPFL
Spring 2022
Teaching Assistant·Foundation of Probabilistic Proofs·EPFL
Fall 2020
Teaching Assistant·Great Ideas in Theoretical Computer Science·Carnegie Mellon University
Spring 2020
Teaching Assistant·Continuous Time Finance·Carnegie Mellon University
Spring 2020
Tutor·Great Ideas in Theoretical Computer Science·Carnegie Mellon University
Fall 2019
Teaching Assistant·Discrete Time Finance·Carnegie Mellon University
Spring 2019
Teaching Assistant·Integration and Approximation·Carnegie Mellon University

Service

Program Committee
Asiacrypt 2026
External Reviewer
Crypto 2026 Eurocrypt 2026 STOC 2026 LATINCRYPT 2025 TCC 2025 Crypto 2025 ICALP 2025 Eurocrypt 2025 QIP 2025 Eurocrypt 2024 TCC 2023 CCC 2023