PhotonLink

Offline peer-to-peer file transfer using optical communication.

PhotonLink enables file transfer between devices using only screens and cameras — no network, no servers, no Bluetooth.

Status: Phase 5 — Color Matrix + Phase 4 Stack

This release merges Phase 4 (efficiency & security) with Phase 5 (Color Matrix transport):

• QR Transfer — reliable bidirectional transfer with ACK/NAK recovery
• Color Matrix Transfer — RGB grid encoding with live camera decode
• Compression — GZip (active); LZ4 placeholder
• Encryption — optional ChaCha20-Poly1305 (setup QR for QR; key embedded in metadata for Color Matrix)
• Payload pipeline — compress → encrypt → chunk (send); reverse on receive
• Transport registry — pluggable encoders/decoders per method
• Settings — compression, encryption, transfer mode, Color Matrix grid size & frame rate
• History — per-method records with compression/encryption metadata

Supported file types: txt, pdf, jpg, png, zip (QR max 512 KB; Color Matrix up to 2 MB).

Quick Start

cd photonlink_app
flutter pub get
flutter run

QR transfer: Device A → QR Transfer → Send → pick file. Device B → QR Transfer → Receive → scan setup (if encrypted), metadata, and data frames.

Color Matrix: Device A → Color Matrix → Send → pick file. Device B → Color Matrix → Receive → align matrix in camera frame.

Enable Compression and/or Encryption in Settings before transferring.

See docs/SETUP.md for platform setup.

Tech Stack

Layer	Technology
Frontend	Flutter 3.22+, Dart 3.3+
State	Riverpod 2
Navigation	go_router
QR	qr_flutter, mobile_scanner
Color Matrix	camera, image
Encryption	cryptography (ChaCha20-Poly1305)
Integrity	crypto (SHA-256)

Tests

cd photonlink_app
flutter test
flutter analyze

Documentation

• Phase 1–5 Audit
• Architecture
• Color Matrix Format
• Security review
• Phase 4 benchmarks
• Performance Summary
• Phase 6 Readiness
• Setup

License

See LICENSE.