Thomas Coratger is a French security and cryptography researcher at the Ethereum Foundation. He is best known for leading the foundation's "Keystone" team, a specialized unit formed in January 2026 to upgrade the Ethereum protocol with post-quantum security measures. His work focuses on applied mathematics, formal verification of protocols, and the development of advanced zero-knowledge proof systems. ^{[1] [2]}​

Education

Coratger holds a Ph.D. in applied mathematics and a Master's degree in Computer Science from the École pour l'informatique et les nouvelles technologies (EPITECH), which he attended from 2017 to 2022. ^{[3] [4]} Before transitioning to the blockchain industry, his doctoral research was applied in the automotive and aeronautic sectors. He has commented on the connection between these fields, stating, "Every day now, I'm amazed by the parallels between solving physics problems and building eth future. Blockchain draws from so many fields — an often underappreciated fact!" ^[3]​

Career

Early Career and Tezos Ecosystem

Coratger's career in the blockchain industry began with an internship at Nomadic Labs, a research and development center within the Tezos ecosystem. From February to July 2021, he worked in Paris with the cryptography team, where his focus was on BLS signatures. ^[4] Following this, he co-founded Checksum in February 2022, a company that provided professional services for both the Tezos and Ethereum blockchains. He was involved with Checksum until June 2023. ^[4]​

Ethereum Foundation

Coratger joined the Ethereum Foundation in July 2023 as an intern, a role he held until March 2024. During this nine-month internship, his work centered on advanced cryptographic topics, particularly zk-SNARKs and the sum-check protocol, which would become central to his later research. ^[4]​

In March 2024, he was promoted to a full-time position as a Security Researcher. In this capacity, he has focused on developing and optimizing proof systems and contributing to the long-term security architecture of the Ethereum network. ^{[4] [5]}​

Keystone Post-Quantum Security Team

In January 2026, the Ethereum Foundation announced the formation of a new, high-priority team named "Keystone," tasked with making the Ethereum protocol resistant to threats from future quantum computers. ^[4] Coratger was appointed to lead this team. The announcement was made public on January 23, 2026, by fellow Ethereum Foundation researcher Justin Drake, who referred to Coratger as "brilliant." ^[2]​

The Keystone team's mandate is to transition Ethereum's core infrastructure, including validator and transaction signatures, to quantum-resistant cryptographic standards. This initiative elevated post-quantum security from a background research topic to a top strategic and engineering priority for the foundation. ^[1] The team's work involves evaluating and implementing new signature schemes, developing post-quantum test networks, and advancing user-facing defenses. ^[6]​

Research and Contributions to Ethereum

Coratger's work spans several critical areas of blockchain security and scalability, including post-quantum cryptography, formal verification, and zero-knowledge proofs.

Post-Quantum (PQ) Cryptography

As the lead of the Keystone team, Coratger's primary focus is on future-proofing Ethereum against the security risks posed by quantum computing, which threatens to break the elliptic curve cryptography currently used to secure the network. ^[2]​

His technical contributions in this area include research and implementation of post-quantum signature schemes. In late January 2026, coinciding with the Keystone team's formation, he made numerous contributions to a repository for a formalized Ethereum specification related to the eXtended Merkle Signature Scheme (XMSS), a stateful hash-based signature scheme known to be resistant to quantum attacks. His work included fixing implementation details of the signature length, the verification function, and the pseudo-random function within the scheme. ^[7]​

The team's research also involves evaluating other potential quantum-resistant signature schemes, such as CRYSTALS-Dilithium, and exploring the use of STARKs (Scalable Transparent Arguments of Knowledge) as a quantum-secure alternative for signatures. In July 2025, Coratger participated in the first "lean Ethereum interop call" to analyze post-quantum devnet proposals from other teams in the ecosystem. ^{[3] [6]}​

Formal Verification and the leanEthereum Project

Coratger is a significant contributor to the leanEthereum project, an initiative dedicated to creating a formal, machine-verifiable specification of the Ethereum consensus protocol using the Lean proof assistant. The goal of formal verification is to mathematically prove the correctness of the protocol's logic, thereby increasing security assurances and eliminating potential bugs before implementation. ^[7]​

His work is concentrated in the leanSpec repository, where he has implemented and tested core components of the consensus mechanism. This includes logic for attestations, block building, state transitions, and the justification and finalization of blocks. He has also contributed to integrating cryptographic primitives, such as the Poseidon2 hash function, and ensuring compatibility with other Ethereum clients. ^[7]​

Zero-Knowledge Proofs and Proving Systems

Coratger has conducted extensive research into zero-knowledge (ZK) proofs, a technology critical for Ethereum's scalability and privacy.

WHIR Protocol

On August 18, 2025, Coratger and co-author Giacomo Fenzi published a research post titled "WHIR for Ethereum." The paper introduced WHIR, a novel hash-based protocol for proximity testing, a component used in modern zk-SNARKs. WHIR is designed to be faster, produce smaller proofs, and be post-quantum secure, aligning with his broader security work. ^[3]​

lea-n Proof System and Sum-check Protocol

He is the creator of lea-n, a proof system based on the sum-check protocol, an interactive proof that is fundamental to many modern SNARK constructions. Much of his public research is dedicated to optimizing the sum-check protocol's prover, handling specific edge cases, and designing related components like a virtual machine (leanVM) and a compiler. He has published extensive technical notes on these topics, including memory models and lookup arguments for leanVM. His work on leanVM has been cited as a "cornerstone" of Ethereum's post-quantum strategy. ^{[4] [2]}​

STARK-based Proving Systems

Coratger is also a contributor to the development of STARK-based proving systems. He has made contributions to Plonky3, an open-source, STARK-based proving system, where he has submitted optimizations for matrix operations. His personal GitHub repositories also contain explorations in Rust related to polynomial interactive oracle proofs (PIOPs) and other cryptographic components of proving systems. ^[7]​

Publications and Technical Writings

Coratger actively publishes technical research and educational material. He is a co-author of EIP-7562, an Ethereum Improvement Proposal for adding precompiles for the BLS12-381 elliptic curve to the EVM, which would support more efficient cryptographic operations on-chain. ^[5]​

He is also a contributor to the "zkEVM book," a work-in-progress publication from the Ethereum Foundation's zkEVM team aimed at educating engineers and researchers. ^[3]​

His public research notes on HackMD cover a wide range of topics, including:

• Lean Consensus: 2026 Plan (November 2025)
• Understanding Ligerito: A Fast, Recursive Polynomial Commitment Scheme (December 2025)
• Optimizing the Sum-Check Prover (October 2025)
• Memory Models & Lookup Arguments in leanVM (September 2025)

These writings, along with his open-source repositories like lea-n, univ-sumcheck-rs, and bls12-377-ark, document his deep engagement with applied cryptography. ^[4]​