Networking on Bitsy Wiki

WebRTC

Mon, 01 Jan 0001 00:00:00 +0000

WebRTC is the browser’s built-in facility for sending audio, video and arbitrary data directly to another browser, or to a server that speaks the same protocols, with encryption that cannot be switched off. It has two halves. The W3C defines the JavaScript API, whose central object is RTCPeerConnection. The IETF defines the protocols underneath: ICE to find a network path, Datagram Transport Layer Security (DTLS) to authenticate the two ends and agree keys, Secure Real-time Transport Protocol (SRTP) for media, and Stream Control Transmission Protocol (SCTP) for data channels. RFC 8825 is the overview.

Nostr

Mon, 01 Jan 0001 00:00:00 +0000

Nostr is a protocol for publishing signed messages through relays. Each user is a key pair on secp256k1, the elliptic curve Bitcoin uses, and each message is an event: a small JSON object carrying the author’s public key, a timestamp, a numeric kind, a list of tags, a text body, and a signature over all of them. A client signs events with the user’s private key and sends them over WebSockets to relays, servers that store events and forward them to clients whose subscriptions match. The base protocol defines no messages between relays. Clients check signatures themselves, so a relay can refuse, drop or withhold an event but cannot alter one or forge one under another key.

Trystero

Mon, 01 Jan 0001 00:00:00 +0000

Trystero is a JavaScript library that connects browsers directly over WebRTC without a signalling server of the application’s own. Before two browsers can open a WebRTC connection they have to swap session descriptions, written in the Session Description Protocol (SDP), and the candidate addresses that ICE finds for each of them. WebRTC leaves the channel for that swap to the application. Trystero sends it through services that other people already run in public: by default Nostr relays, servers that forward signed messages between any clients that ask, and in other packages BitTorrent trackers, public brokers for MQTT (a publish–subscribe protocol for small devices) or a hosted database. Browsers that join the same room find each other there, exchange encrypted offers and answers, and end up with a direct WebRTC connection. After that, application data no longer passes through the relays.