Portrait of Stefanos Chaliasos

Stefanos Chaliasos

Senior Security Researcher, zkSecurity
Marie Skłodowska-Curie Fellow, University of Athens

I am a Senior Security Researcher at zkSecurity, where I audit protocols built on zero-knowledge proofs and other advanced cryptography and do research on protocol security and vulnerability detection, including AI-based vulnerability detection, and a Marie Skłodowska-Curie Fellow at the National and Kapodistrian University of Athens. Previously, I was an Assistant Professor in Computational Economics and Finance at UCL.

I work at the intersection of security, programming languages and software engineering, and applied cryptography. My goal is to make advanced cryptographic systems, such as zero-knowledge proofs, secure in practice when instantiated as software, compilers, and protocols. To that end, I develop program analysis, testing, and formal verification techniques, combined with LLMs, to find and prevent vulnerabilities, and use mechanism design to reason about the incentives of decentralized systems built on them.

I completed my PhD at Imperial College London in 2025, advised by Benjamin Livshits and Alastair Donaldson, with a thesis on the practical analysis of zero-knowledge proof implementations. Before that I held research and engineering roles at Matter Labs, Veridise, the Athens University of Economics and Business, and GRNET.

I have built LLM-enhanced security pipelines that detected vulnerabilities in cryptographic libraries from Cloudflare, Bron, and other state-of-the-art projects. I am also an active white-hat hacker: I have discovered zero-day vulnerabilities in live systems securing billions of USD and received bug bounties from Tools for Humanity, Optimism, Linea, zkSync Era, OpenVM, and Cosmos.

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