Ziyang Jin

 

 

Hi there, welcome to my homepage!

I am a Ph.D. student studying theoretical computer science (TCS) at the University of Toronto (UofT), where I am very fortunate to be supervised by Akshayaram Srinivasan to work on exciting topics in cryptography. Previously, I completed my M.Sc. in computer science also at UofT, under great supervision of Mike Molloy in graph theory. Before that, I worked as a software enigneer. A few years ago, I obtained a B.Sc. in computer science at The University of British Columbia (UBC) [1], where I was inspired by Will Evans and Nick Harvey to study theoretical computer science. Feel free to drop me an email for your great research ideas, or just say hi to me.

More specifically, my research interests lie in:

• Secure Multiparty Computation (MPC): Secure multiparty computation (MPC) is about constructing protocols for $n$ parties to jointly compute a functionality $f(x_1,\; ...\; ,x_{\mathrm{n}})$ while keeping each party's input $x_i$ private. Furthermore, if a subset of parties are corrupted by an adversary, these corrupted parties jointly cannot learn anything beyond what can be inferred from their own private inputs and the function output. Two main types of adversaries are usually considered: semi-honest adversary and malicious adversary. A semi-honest adversary follows the protocol specification but tries to learn extra information from its transcript of communication. On the other hand, a malicious adversary can deviate from the protocol arbitrarily. Some well-known MPC protocols are [Yao86], [GMW87], [BGW88], [CCD88], [BMR90].
• Zero-Knowledge Proofs (ZKP): In a common setup, there are two parties, the prover and the verifier. The prover has unbounded computation power while the verifier runs in probablistic polynomial time. A zero-knowledge proof [GMR85][Babai85] allows the prover to prove a statement to the verifier such that the verifier does not learn any information (regarding how the statement is proved) other than the statement is true. This is achieved by interactions between the prover and the verifier. The verifier asks some questions about the statement and if the statement is true, the prover should be able to answer these questions correctly. If the statement is false, the prover fails to answer the questions with a noticeable probability, even if the prover has unbounded computation power. Zero-knowledge means that for true statements, if the verifier can simulate the interaction with the prover in its own head such that the view of the verifier is indistinguishable between the real interaction with the prover and the simulation by the verifier itself, then the verifier does not gain "knowledge" [2].

I also like game theory, complexity theory, and coding theory. I am also interested in applying cryptography to real-world applications.

Email: [first-name] [at] cs [dot] toronto [dot] edu | LinkedIn | GitHub

Papers

1. Non-Interactive Secure Computation with Constant Communication Overhead
   with Yuval Ishai, Naty Peter, Akshayaram Srinivasan
   to appear in the 45th Annual International Conference on the Theory and Applications of Cryptographic Techniques [Eurocrypt 2026]

Thesis

1. [Master's Thesis] Frugal Colouring of Graphs with Girth At Least Five
   • We proved that for any graph with girth at least five and maximum degree $d$, there exists a $(1+o(1))(d/\ln d)$-colouring such that for every vertex $v$, no colour appears more than polylog($d$) times in the neighbourhood of $v$. Our work employs a technique called the semi-random method (a.k.a. the Rödl Nibble) and bases on the proof in [Kim95] for bounding the chromatic number of girth five graphs. We use a non-trivial lopsided Lovász Local Lemma to complete the colouring.

Other Publications

1. Classical Verification of Quantum Computations (from Yael Kalai's talk)
   Fields Notes (Fields Institute Newsletter), 21:7 (Winter 2026), pp. 19-21. The Fields Institute for Research in Mathematical Sciences.

Selected Talks

Date	Institute	Event	Title
2026-01-14	University of Toronto	Crypto Reading Group	A New Approach to Large Party Beaver-Style MPC with Small Computational Overhead [JLS25]
2025-02-27	University of Toronto	Theory Student Seminar	Polishchuk-Spielman Bivariate Testing and An Application [PS94]
2025-01-17	University of Toronto	Crypto Reading Group	SNARGs under LWE via propositional proofs [JKLV24]
2025-01-10	University of Toronto	Crypto Reading Group	Universal SNARGs for NP from Proofs of Correctness [JKLM24]
2024-06-13	University of Toronto	Theory Reading Group	Public-Key Encryption, Local Pseudorandom Generators, and the Low-Degree Method [BKR23]
2024-01-24	University of Toronto	Theory Student Seminar	Frugal Colouring of Graphs with Girth At Least Five
2023-10-11	University of Toronto	Theory Student Seminar	Graph Colouring and the Rödl Nibble
2023-04-26	University of Toronto	Theory Student Seminar	The Probabilistic Method and Entropy Compression

Unpublished Write-ups

2024	Non-Interactive Zero-Knowledge Proof of 3-Colouring	Notes
2024	Doubly Efficient Proof Systems [GKR08]	Notes and Slides
2023	Entropy Compression and Frugal Colouring	Notes
2022	The Puzzle Toad No. 39	Our solution

• Reviewer: ICALP 2024, Crypto 2025, TCC 2025

University of Toronto
Term	Role	Course Code	Title	Notes
2026 Winter	TA	CSC 310	Information Theory	Tutorial 1 Tutorial 2 Tutorial 4 Tutorial 5 Tutorial 6
2026 Winter	TA	CSC 373	Algorithm Design, Analysis, and Complexity
2025 Fall	TA	CSC 463	Computational Complexity and Computability
2025 Fall	Lead TA	CSC 364	Foundations of Computer Security
2025 Winter	Lead TA	CSC 165	Mathematical Expression and Reasoning for Computer Science
2025 Winter	TA/mentor	PRISM	Preparation for Research through Immersion, Skills, and Mentorship
2024 Fall	TA	CSC WDI (UTM)	Writing Development Initiative for CSC207, CSC258, CSC236, CSC373
2024 Fall	TA	CSC 263	Data Structures and Analysis
2024 Winter	TA	CSC 310	Information Theory
2024 Winter	Lead TA	CSC 373	Algorithm Design, Analysis, and Complexity
2023 Fall	Instructor [3]	CSC 236	Introduction to the Theory of Computation
2023 Summer	Prep TA [4]	CSC 240	Enriched Introduction to the Theory of Computation
2023 Winter	Instructor [3]	CSC 373	Algorithm Design, Analysis, and Complexity
The University of British Columbia
Term	Role	Course Code	Title
2019 Winter	UTA	CPSC 320	Intermediate Algorithm Design and Analysis
2018 Fall	UTA	CPSC 311	Definition of Programming Languages
2018 Winter	UTA	CPSC 313	Computer Hardware and Operating Systems
2016 Summer & Fall	UTA	CPSC 221	Basic Algorithms and Data Structures
2015 Summer & Fall, 2016 Winter	UTA	CPSC 121	Models of Computation

• I am a volunteer for the Undergraduate Student Research Program (USRP) organized by UofT's Computer Science Student Union (CSSU) on Feb 2, 2026.
• I am a volunteer for the 2nd Ontario Cryptography Day on Nov 28, 2025.
• I am a volunteer for the MSc/PhD booth in the 2025 DCS Graduate School Open House on Oct 25, 2025.
• I am a student ambassador for 2025 Grad Visit Day and a current student panel speaker on Mar 18, 2025.
• [GAAP 2024] The Toronto Graduate Application Assistance Program is a student-run, volunteer-led program to help students prepare applications to MSc and PhD program in computer science at UofT. I was a mentor in year 2024-2025, mainly for applicants who are interested in theoretical computer science.

If you are an undergrad at UofT and interested in cryptography, especially secure multi-party computation (MPC), I am happy to supervise a reading project on MPC. A reading projects is where many theory students start their research, by first learning the fundamentals and classical results. I will give you a series of textbook chapters/papers about MPC to read, and we will meet for 30 minutes every week where you explain the paper in your own words. If by chance we happen to find some interesting problem to work on together, then we can extend it to a full research project.

If you are interested, feel free to send me an email with your transcript and explain your motivation to do research in cryptography, or TCS in general.

• If you are applying for a CS PhD, especially for a theory group, then I recommend Roei Tell's suggestion on how to write the Statement of Purpose
• [Theory Website Contribution] You are welcome to contribute to the theory group's official website. Having a modern, up-to-date website is crucial for us to attract students and researchers to our group.
• [Theory Student Seminar] We are looking for speakers. If you are a researcher in theoretical computer science and would like to give a talk, feel free to email tssadmin@cs.toronto.edu
• [Life in Toronto] My personal recommendations for living in Toronto.

• Access ACM Ditigal Library as UofT student: Login to UofT library, and search for "ACM Digital Library" from DATABASE SEARCH, and then follow the link.
• View final exam schedule as a TA: log in to LSM Final Exam Couse Schedule - Power BI.

• [1] Not a typo. The word "The" is part of the official name of The University of British Columbia.
• [2] A YouTube video that explains the concept of zero-knowledge proofs by Amit Sahai: Computer Scientist Explains One Concept in 5 Levels of Difficulty | WIRED.
• [3] If you need one last recommendation letter for gradudate school applications, I am happy to write a letter for you. Note that I can only write about your course performance; I am unable to comment on your research abilities if you have never worked with me on research projects.
• [4] I draft assignment questions and solutions under the supervision of Faith Ellen to prepare for CSC 240 in 2024 Winter.