A Serverless WebRTC Signaling Protocol Using QR Codes(magarcia.io)
magarcia.io
A Serverless WebRTC Signaling Protocol Using QR Codes
https://magarcia.io/air-gapped-webrtc-breaking-the-qr-limit
3 comments
Love the creativity and that you took the time to explain every step of the discovery.
Thanks! The write-up took longer than the actual protocol design.
WebRTC signaling SDPs are ~2.5KB. Too large for practical QR scanning. When you control both endpoints, most of that is unnecessary ceremony.
Key insights: derive ICE credentials from DTLS fingerprint via HKDF, use binary encoding (IP as 4 bytes not ASCII), skip compression (DEFLATE increases size on high-entropy data), skip base64 (QR supports raw binary).