Enhance WebRTC Pvt-to-Pvt example by WebRTC Direct SDP Exchange via QR Code

[Nkovaturient]

Description [Discussed here- #208 ]

This proposal aims to enable browser-to-browser WebRTC connections without a relay server, allowing users to establish private, offline, peer-to-peer communication. The SDP exchange happens via QR codes instead of a centralized signaling server, making it ideal for censorship-heavy regions, offline scenarios, or restricted networks (e.g., Bluetooth-based networks). The proposal can enhance libp2p and IPFS use cases by enabling peer discovery and direct communication when traditional internet-based methods fail.

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How It Works

1. Browser A (Initiator)

   • Generates an SDP offer using WebRTC APIs.
   • Optionally gathers ICE candidates (STUN helps but is not mandatory).
   • Encodes the SDP offer as a QR Code (or a sharable text file).

2. Browser B (Receiver)

   • Scans the QR code (or manually imports the SDP file).
   • Creates an SDP answer based on the received offer.
   • Encodes its SDP answer as another QR Code (or shares it manually).
   • Both browsers exchange ICE candidates manually if needed.

3. Establishing Connection

   • Once both browsers have exchanged SDP offers/answers & ICE candidates, WebRTC establishes a direct P2P connection.
   • The connection is now independent of the initial exchange method.

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Features

• Decentralized WebRTC Connection: No signaling server or relay node required.
• Offline Communication: Works without WiFi, internet, or public relays.
• QR Code-based SDP Exchange: Secure and simple method for peer-to-peer connection setup.
• Manual ICE Candidate Exchange: Enables direct connections even in NAT-restricted environments.
• Bluetooth/NFC Support (Future Scope): Enhance SDP exchange for truly offline networking.
• Improved Privacy: No third-party server involvement.
• libp2p/IPFS Compatibility: Can be integrated with libp2p for ad-hoc network formation.

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Challenges

• NAT Traversal Issues: If both peers are behind a strict NAT, connection may fail without a TURN server.
• Manual ICE Candidate Exchange: Some setups may require multiple QR code scans.
• QR Code Size Limitations: Long SDPs may require text-based exchange instead.
• Limited Browser Bluetooth API: Current Web Bluetooth APIs may not support large SDP exchanges.
• User Experience Considerations: Multiple scans or manual text pasting may affect usability.

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Advantages

✅ No relay servers → Works in censorship-heavy areas.
✅ Offline-first → Works in areas with no internet.
✅ No central authority → Ensures privacy & security.
✅ Supports Bluetooth/NFC → Expands connectivity options.
✅ Can integrate with libp2p → Enables decentralized peer discovery.

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Next Steps

• Implementing a proof-of-concept WebRTC QR Code exchange demo.
• Exploring Bluetooth API/NFC for local SDP transfer.
• Investigating libp2p integration for identity & multi-hop networking.

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Relevant Links:

• WebRTC.org Examples
• libp2p WebRTC Direct Transport
• Web Bluetooth API

[NiKrause]

I think it is not necessary that browser B needs to generate another QR Code.
Based on the offer of A, B can already create a DataChannel to A and send his answer to A via A's channel, then A can communicate with B too!