Marius-Florin Cristian
Marius-Florin Cristian is a computer scientist and the author of KeibiDrop, an open-source post-quantum encrypted file transfer tool. He holds a CISSP certification and a Master's degree in Computer Science from the University of Copenhagen (DIKU), where his thesis addressed the minimum spanning tree problem in the context of linear-time complexity. He served as CISO at two B2B SaaS startups in Copenhagen---Krizo.io and Omnio.net---where he built cybersecurity programs from scratch (ISO 27001 ISMS, NIST RMF/800-53, risk management) while simultaneously contributing to product development (Haskell at Krizo, Rust at Omnio), managing DevOps and Kubernetes infrastructure, and shipping features in sprints---both acquired within two years of his joining. After Omnio's acquisition by IBM, he worked briefly as a Senior Cybersecurity Specialist at IBM before moving to Romania to build KeibiSoft full-time. He works across the full stack---from cryptographic protocol design and threat modeling to systems programming and infrastructure---doing whatever it takes to ship.
Session
We present KeibiDrop, an open-source (MPL 2.0) peer-to-peer file transfer tool that provides end-to-end encryption using a hybrid post-quantum key exchange (ML-KEM-1024 + X25519) with ChaCha20-Poly1305 at the transport layer. KeibiDrop operates over direct IPv6 connections with no cloud intermediary, no STUN/TURN servers, and no persistent metadata. The relay server is treated as an untrusted blind intermediary: it sees only opaque lookup keys and encrypted blobs, and cannot correlate users or decrypt content. We discuss the cryptographic design, the privacy model, the trade-offs of an IPv6-only architecture, and the practical challenges of mounting remote files as a local FUSE filesystem with forward secrecy via automatic re-keying. A live demonstration accompanies the talk.