bitchat Technical Whitepaper

bitchat Protocol Whitepaper v2.0, dated July 6, 2026, describes a decentralized messaging app that uses an ad-hoc Bluetooth Low Energy mesh for nearby devices and the Nostr protocol for distant peers. Messages reach peers who are out of range at send time through a store-and-forward stack, including a sender outbox, couriers using a spray-and-wait copy budget, gossip-synced public history, and Nostr relay mailboxes. Live sessions use Noise XX, while courier envelopes use Noise X, which provides no forward secrecy. The document states that media such as images and voice notes is written to disk unsealed, and that unlinkable presence is not currently provided.