RTC Pair Socket

RtcPairSocket is a lightweight TypeScript class for establishing encrypted peer-to-peer communication between two parties (Alice and Bob) using PeerJS and an encryption layer. This library facilitates encrypted message exchange over WebRTC, with events to handle connection, data, and errors.

Features

• Secure peer-to-peer communication using WebRTC and PeerJS.
• Symmetric encryption using a pairing code.
• Event-based architecture for handling connection, messages, and errors.
• Minimal dependencies.

Installation

To install the dependencies, run:

npm install

Usage

import RtcPairSocket from "./RtcPairSocket";

const pairingCode = "your-secret-code";
const party = "alice"; // or 'bob'

const socket = new RtcPairSocket(pairingCode, party);

socket.on("open", () => {
  console.log("Connection opened!");
});

socket.on("message", (data) => {
  console.log("Received message:", data);
});

socket.on("error", (err) => {
  console.error("Error:", err);
});

socket.on("close", () => {
  console.log("Connection closed.");
});

// To send a message
socket.send("Hello, Bob!");

// You can also send structures and they'll be reconstructed on the other side
// (not classes though, basically json plus undefined and Uint8Array)
socket.send([1, 2, "three"]);

Turn Servers / Reliability

Out of the box, you might experience reliability issues when users are behind NAT networks. Ideally WebRTC enables direct communication between clients, but this isn't always successful. In this case, a TURN server can provide a reliable fallback option which is basically a relay.

To use it, run a turn server or use a service like ExpressTURN and provide a third parameter like this to RtcPairSocket:

new RtcPairSocket(pairingCode, party, {
  config: {
    iceServers: [
      // Google's free stun server. It's important to include this one.
      { urls: "stun:stun.l.google.com:19302" },

      // Your turn server. Replace each field with values specific to your setup.
      {
        urls: "turn:your-turn-server.com:3478",
        username: "your-username",
        credential: "your-password",
      },
    ],
  },
  // optional: other PeerOptions (see PeerJS)
});

In many cases, RtcPairSocket will work without this extra step.

Events

• open: Emitted when the connection is successfully established.
• message: Emitted when an encrypted message is received.
• error: Emitted when an error occurs.
• close: Emitted when the connection is closed.

Methods

• send(data: unknown): Sends encrypted data to the connected peer.
• close(): Closes the connection.
• isClosed(): Returns true if the connection is closed.

How it Works

• Pairing Code: A shared secret is used as the seed for generating a symmetric encryption key. This ensures that only Alice and Bob can decrypt each other's messages.
• Peer Connection: Depending on the party (alice or bob), the socket establishes a WebRTC connection to the other party.
• Encryption: All messages sent over the connection are encrypted using the Cipher class, which encrypts and decrypts data using the shared key.

License

This project is licensed under the MIT License.