Whitepaper - LumaChat

Executive Summary

"Server LumaChat tidak dapat membaca pesan Anda. Data terenkripsi hanya bisa dibuka oleh Anda dan penerima."

LumaChat adalah platform perpesanan generasi berikutnya yang menggabungkan enkripsi tingkat enterprise, komunikasi real-time, dan estetika budaya yang terinspirasi dari batik Indonesia.

Key Highlights

Signal Protocol (X3DH + Double Ratchet) LINK ID System Zero-Knowledge Server 100MB+ File Upload Per-Chat Privacy WebRTC Calls Flutter Cross-Platform

Visi & Misi

Visi

LumaChat membayangkan dunia di mana komunikasi yang aman dapat diakses oleh semua orang tanpa mengorbankan privasi, kegunaan, atau identitas budaya.

Misi

Menyediakan platform perpesanan yang:

Mengimplementasikan enkripsi end-to-end standar industri
Tidak memerlukan nomor telepon (LINK ID)
Memberikan kontrol privasi penuh kepada pengguna
Menggabungkan desain budaya Indonesia

Core Values

Value	Deskripsi
Privacy First	Privasi bukan fitur, tapi fondasi
Zero Knowledge	Server tidak bisa membaca pesan
User Control	Pengguna memiliki kontrol penuh
Transparency	Arsitektur terdokumentasi

Technology Stack

Frontend (Mobile)

Technology	Version	Purpose
Flutter	3.x	Cross-platform framework
Riverpod	2.6.1	State management
Isar	3.1.0	Local database
cryptography	2.7.0	Signal Protocol
flutter_webrtc	0.12.4	Voice/Video calls

Backend

Technology	Version	Purpose
Node.js	18+	Runtime
Express	4.18.2	REST API
WebSocket (ws)	8.16.0	Real-time messaging
SQLite	better-sqlite3	Metadata storage
MinIO	7.1.3	Encrypted media storage

Security & Encryption

Signal Protocol

LumaChat mengimplementasikan Signal Protocol dengan komponen:

X3DH (Extended Triple Diffie-Hellman) - Key exchange
Double Ratchet - Forward secrecy per message
AES-256-GCM - Symmetric encryption
X25519 - Elliptic curve key pairs

E2EE Scope

Data Type	E2EE	Notes
Text Messages	✅ Yes	Encrypted on device
Media Files	✅ Yes	AES-GCM before upload
Voice/Video Calls	✅ Yes	WebRTC DTLS-SRTP
Metadata	TLS only	Sender/recipient IDs

Key Management

Key Type	Rotation	Storage
Identity Key	Never (unless compromised)	Secure storage
Signed PreKey	Every 7 days	Server (public only)
One-Time PreKey	Single use	Server (public only)
Session Key	Per message (ratchet)	Device memory

Feature Set

Core Features

LINK ID System - Unique identifier (LX-XXXX-XXXX), no phone required
E2E Encrypted Messaging - Text, media, documents
Voice & Video Calls - WebRTC with LiveKit SFU
Group Chat - Multi-participant conversations
Diary (Stories) - 24-hour ephemeral content

Privacy Features (v2.8.7+)

Per-Chat Privacy Controls - Disappearing messages, media cache per chat
Encryption Transparency - Privacy Badge, session fingerprint
Privacy Presets - Default, High Privacy, Maximum Privacy
Email Recovery - Optional account recovery

Technical Features

Chunked Media Upload - 100MB+ files with 256KB chunks
Data-Only FCM - Privacy-preserving push notifications
WebSocket Real-time - Sub-second message delivery
Offline-First - Local database with sync

Architecture Overview

┌─────────────────────────────────────────────────────────────┐
│                     CLIENT (Flutter)                         │
│  ┌─────────────┐  ┌─────────────┐  ┌─────────────┐          │
│  │   UI Layer  │  │   Riverpod  │  │    Isar     │          │
│  │  (Widgets)  │  │   (State)   │  │  (Local DB) │          │
│  └──────┬──────┘  └──────┬──────┘  └──────┬──────┘          │
│         └────────────────┼────────────────┘                  │
│                          ▼                                   │
│  ┌─────────────────────────────────────────────────────┐    │
│  │              Services Layer (Encryption)             │    │
│  │   Signal Protocol │ WebSocket │ WebRTC │ FCM        │    │
│  └─────────────────────────────────────────────────────┘    │
└─────────────────────────────┬───────────────────────────────┘
                              │ HTTPS/WSS (TLS 1.2+)
                              ▼
┌─────────────────────────────────────────────────────────────┐
│                     SERVER (Node.js)                         │
│  ┌─────────────┐  ┌─────────────┐  ┌─────────────┐          │
│  │   Express   │  │  WebSocket  │  │   SQLite    │          │
│  │  (REST API) │  │  (Real-time)│  │ (Metadata)  │          │
│  └──────┬──────┘  └──────┬──────┘  └──────┬──────┘          │
│         └────────────────┼────────────────┘                  │
│                          ▼                                   │
│  ┌─────────────────────────────────────────────────────┐    │
│  │                 MinIO (Encrypted Blobs)              │    │
│  │         Server has NO decryption keys                │    │
│  └─────────────────────────────────────────────────────┘    │
└─────────────────────────────────────────────────────────────┘

Roadmap

✅ Completed (v2.8.7 - v2.9.x)

Conversation Transparency Mode
Per-Chat Privacy Profile
Proof-of-Privacy Badge
Chunked Media Upload (100MB+)
Data-Only FCM

🔜 Phase 2 (v3.0.x)

Offline-First Superpower - Seamless offline queue
Message Integrity Receipt - Cryptographic verification
Ephemeral Media Firewall - View-once media

📅 Phase 3 (v3.2.x+)

Desktop apps (Windows, macOS, Linux)
E2E encrypted backups
Multi-account support

Full Technical Whitepaper

Untuk dokumentasi teknis lengkap termasuk API reference, database schema, dan implementation details, hubungi tim development.

dev@lumachat.xyz

LumaChat Whitepaper