How should group chats work in decentralized systems?
4 hours ago
- #decentralized-messaging
- #group-chats
- #p2p-systems
- Central servers simplify group chats by handling membership, key distribution, message ordering, and offline messaging, which decentralized systems lack.
- Decentralized group chat models considered include using a coordinating server (centralized), MLS/TreeKEM (scalable but server-dependent), leaderless membership (prone to conflicts), and fixed membership (static groups).
- The implemented solution uses a single creator for membership management, rotated sender keys per epoch, key rotation on membership changes, an append-only log in DHT for state distribution, and per-sender sequences for ordering and offline messaging.
- Tradeoffs involve single-creator authority (single point of failure), sender keys over MLS (limited forward secrecy within epochs), and best-effort ordering without global clocks.