Kostas Chalkias
Software Engineer at Facebook
Menlo Park, California, United States
Summary
🤩
RockstarKostas Chalkias is a software engineer and applied cryptographer with nine years of experience building and hardening cryptographic systems for high-profile blockchain projects. Based in Menlo Park, he has contributed core crypto work to Corda, Diem, Sui and Mysten Labs—implementing deterministic key generation, Ed25519 batch and threshold signature verification, and improving key encoding and signature metadata handling. He blends backend engineering and security rigor to deliver maintainable, high-performance crypto libraries, adding benchmarks, tests and refactors that reduce technical debt. Notably, his contributions span both protocol-level signature verification optimizations and developer-facing improvements that preserve backward compatibility across ecosystems.
9 years of coding experience
Stackoverflow
4,111reputation
3.2mreached
174answers
3questions
java
top-5%
algorithm
top-5%
Github Skills (33)
testing10
distributed-ledger-technology10
signature-verification10
key-management10
digital-signature10
java10
ecdsa10
distributed-ledger10
javas10
secp256k110
eddsa10
cryptography10
blockchain10
ed2551910
smart-contracts10
Programming languages (11)
Github contributions (5)
corda/corda
Feb 2017 - Nov 2018
Corda is an open source blockchain project, designed for business from the start. Only Corda allows you to build interoperable blockchain networks that transact in strict privacy. Corda's smart contract technology allows businesses to transact directly, with value.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:3 releases, 127 commits, 245 PRs in 1 year 9 months
Contributions summary:Kostas contributed to the core cryptographic libraries within the Corda project, focusing on digital signatures and key management. They implemented deterministic key generation for various signature schemes, improving the framework's cryptographic agility. They also introduced enhancements for handling transaction signatures, including metadata and support for composite keys. Furthermore, they refactored code for key encoding and decoding, enhancing overall maintainability.
interoperabledltsmart-contractprivacytransact
diem/diem
Jul 2019 - Jun 2021
Diem’s mission is to build a trusted and innovative financial network that empowers people and businesses around the world.
Role in this project:Back-end Developer & Security Engineer
Back-end Developer & Security EngineerContributions:49 reviews, 37 commits, 43 PRs in 1 year 11 months
Contributions summary:Kostas made significant contributions to the cryptographic aspects of the Diem blockchain project. Their work included implementing and optimizing Ed25519 batch signature verification and fixing linker errors related to native signature verification. Further contributions involved updating and refactoring cryptographic components with a focus on improved security and efficiency, and the implementation of threshold signature verification.
diemfinancialtrustedethereumblockchain
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