Case Study — Mobile

Whisper Chat App

A secure, end-to-end encrypted chat application utilizing the Signal protocol for private messaging.

Project Overview

Whisper guarantees privacy by implementing the Signal double-ratchet encryption protocol. All messages, voice notes, and media are encrypted locally before transmission, ensuring that no interceptor can read logs.

Key Features & Scope

End-to-end encryption with secure key verification codes

Peer-to-peer audio and video calls powered by WebRTC connections

Disappearing messages disappearing from all devices after set timers

Biometric security gates requiring fingerprint scans upon openings

System Architecture

React Native with custom native modules for crypto libraries. Node.js backend handles signaling for WebRTC and relays offline messages.

Client InterfaceReact Native / Expo
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Backend CoreNode.js / Express
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Database NodeSQLite (with SQLCipher encryption)
Database: SQLite (with SQLCipher encryption)
Deployment: Google Play Store & VPS
App Startup Time1.4s
JS Bundle Size6.5 MB
Crash-Free Rate99.97%
Render Frame Rate60 FPS
Verified Production Metrics
React NativeExpoWebRTCSQLiteNode.jsSocket.IOTypeScript

Keywords and concepts covered in this project case study:

Whisper Encrypted ChatReact Native Signal ProtocolWebRTC mobile video callingSQLite SQLCipher secure chat

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