Kostas Chalkias

Research Scientist

I hold a PhD in identity-based encryption, and am a cryptographer at Novi, focusing on privacy-preserving protocols and contributing to the Diem (formerly Libra) project’s crypto API. Before joining Novi, I was the lead cryptographer at R3, one of the biggest blockchain banking consortia, mainly dealing with secure smart contracts for finance. Prior to that, I was the CTO of two security and machine learning startups (Erybo and Safemarket), where I built a platform for fair and secure national exams and quiz platforms using time-lapse cryptography. My fields of expertise include timed-release encryption, auditing protocols, secure enclaves, graphical passwords, and post-quantum cryptography. I also implemented and found critical bugs in a number of smart contracts in the past, such as atomic swaps and multi-party apps on blockchain, including decentralized lotteries, lightning chess, and card games.


Cryptograpic schemes and attacks: zero knowledge proofs, post-quantum, SGX, timed-release encryption, graphical passwords, biometrics, distributed randomness

Latest Publications

SSR - October 22, 2020

Taming the many EdDSAs

Kostas Chalkias, François Garillot, Valeria Nikolaenko

ZKProof - April 22, 2020

Distributed Auditing Proofs of Liabilities

Kostas Chalkias, Kevin Lewi, Payman Mohassel, Valeria Nikolaenko