🔐 2FAir - E2E Encrypted TOTP Vault

Status: ✅ Phase 3 Complete - Clean Architecture + PRF Implementation (Core Complete, Not Production Ready)

🎉 Phase 3 Milestone Achieved (January 2025):

• ✅ Clean Architecture implementation with Uncle Bob's principles
• ✅ WebAuthn PRF support with HKDF key derivation
• ✅ Universal fallback compatibility for all devices
• ✅ Complete zero-knowledge encryption architecture
• ✅ Core features complete with comprehensive security
• ✅ Modern React frontend with landing pages and animations
• 🚧 Phase 4 Required for Production: Multi-Device Sync & Production Hardening

2FAir is a zero-knowledge, end-to-end encrypted TOTP (Time-based One-Time Password) vault that puts security and privacy first. Your TOTP secrets are encrypted client-side using WebAuthn-derived keys with PRF (Pseudo-Random Function) support, ensuring the server never sees your plaintext data.

🎯 Current Implementation Status - Phase 3 Complete ✅

🏗️ Clean Architecture Implementation ✅ NEW

• Domain-Driven Design: Proper separation of concerns with domain, application, infrastructure, and interface layers
• SOLID Principles: Dependency inversion, interface segregation, and clean dependencies
• Package Organization: Domain-specific directories (crypto, totp, webauthn) following Go best practices
• Interface-Based Design: All services implement domain interfaces for testability and maintainability
• No Import Cycles: Clean dependency graph with proper architectural boundaries

🔒 Enhanced Zero-Knowledge Security ✅ COMPLETE

• PRF-First Key Derivation: WebAuthn PRF → HKDF-SHA256 → AES-256-GCM key (when available)
• Universal Fallback: credential.id → PBKDF2-SHA256 → AES-256-GCM key (for compatibility)
• End-to-End Encryption: AES-256-GCM with client-side encryption
• WebAuthn Integration: Hardware-backed key derivation from biometric/security keys
• No Server Access: Server never sees plaintext TOTP secrets or codes
• Session-Based Keys: Consistent encryption keys throughout the browser session

🚀 Modern TOTP Management ✅ COMPLETE

• Client-Side Generation: All TOTP codes generated using the otpauth library
• Real-Time Updates: Codes auto-refresh every 30 seconds with progress indicators
• Multi-Algorithm Support: SHA1, SHA256, SHA512 algorithms
• Standard Compatibility: Works with Google Authenticator, Authy, and all TOTP apps
• QR Code Import: Import TOTP secrets via QR code scanning

🌐 Full-Stack Application ✅ COMPLETE

• React Frontend: TypeScript + HeroUI + TanStack Query + Zustand state management
• Go Backend: Clean architecture + Gin framework + PostgreSQL + SQLC + WebAuthn PRF
• OAuth Authentication: Google OAuth 2.0 integration
• WebAuthn Registration: Complete credential management with PRF support
• Responsive Design: Beautiful UI that works on desktop and mobile browsers

🛡️ Production-Grade Security ✅ COMPLETE

• Clean Architecture: Proper layer separation for security and maintainability
• PRF Extension: WebAuthn Pseudo-Random Function for optimal security
• HKDF Key Derivation: RFC 5869 compliant key derivation from PRF
• Comprehensive Validation: Input validation at all layers
• Security Headers: CORS, CSP, HSTS, and security headers configured
• Authentication Required: All endpoints properly protected with JWT + WebAuthn
• Audit Trail: Comprehensive logging for security events

📋 Quick Start

Prerequisites

• Docker & Docker Compose (recommended for quickest setup)
• Go 1.22+ (for local development)
• Node.js 18+ & Yarn (for frontend development)
• PostgreSQL 15+ (for local database)

🐳 Docker Setup (Recommended)

# Clone repository
git clone <repository-url>
cd 2FAir

# Start all services (frontend, backend, database)
docker-compose -f server/docker-compose.dev.yaml up -d

# Check service health
docker-compose -f server/docker-compose.dev.yaml ps

Services will be available at:

• Frontend: http://localhost:5173 (React + Vite dev server)
• Backend API: http://localhost:8080 (Go + Gin API)
• Database: localhost:5432 (PostgreSQL)

🔧 Manual Development Setup

1. Backend Setup

# Navigate to server directory
cd server

# Install dependencies
go mod download

# Set up environment variables
cp .env.example .env
# Edit .env with your configuration (see server/README.md)

# Start PostgreSQL (via Docker)
make db-up

# Generate SQLC code
make generate

# Run database migrations
go run ./cmd/server -migrate up

# Start backend server
make run
# or: go run cmd/server/main.go

2. Frontend Setup

# Navigate to client directory  
cd client

# Install dependencies
yarn install

# Set up environment variables
cp .env.example .env.local
# Edit .env.local with your backend URL

# Start development server
yarn dev

3. Verify Setup

# Test backend health
curl http://localhost:8080/health

# Test frontend
open http://localhost:5173

🏗️ Clean Architecture

Current Implementation - Phase 3 Complete ✅

┌─────────────────────────────────────────────────────────────────┐
│                        Client (React)                          │
│ ┌─────────────────┐ ┌─────────────────┐ ┌─────────────────┐   │
│ │   Components    │ │   Hooks         │ │   State Mgmt    │   │
│ │ • HeroUI        │ │ • TanStack      │ │ • Zustand       │   │
│ │ • WebAuthn PRF  │ │ • Auth hooks    │ │ • OTP state     │   │
│ │ • TOTP UI       │ │ • OTP hooks     │ │ • Auth state    │   │
│ └─────────────────┘ └─────────────────┘ └─────────────────┘   │
└─────────────────────────────────────────────────────────────────┘
                              │ HTTPS/JSON
                              ▼
┌─────────────────────────────────────────────────────────────────┐
│                    Server (Go - Clean Architecture)            │
│                                                                 │
│ ┌─────────────────────────────────────────────────────────────┐ │
│ │                 interfaces/http/ (Interface Layer)         │ │
│ │ • Gin Handlers    • Middleware    • HTTP Server           │ │
│ └─────────────────────────────────────────────────────────────┘ │
│                              │                                 │
│ ┌─────────────────────────────────────────────────────────────┐ │
│ │              application/usecases/ (Application Layer)     │ │
│ │ • Auth Service    • OTP Service    • Business Logic       │ │
│ └─────────────────────────────────────────────────────────────┘ │
│                              │                                 │
│ ┌─────────────────────────────────────────────────────────────┐ │
│ │                domain/ (Domain Layer)                      │ │
│ │ ┌─────────────┐ ┌─────────────┐ ┌─────────────────────────┐ │ │
│ │ │  entities/  │ │ interfaces/ │ │         dto/            │ │ │
│ │ │ • User      │ │ • AuthSvc   │ │ • Request/Response      │ │ │
│ │ │ • OTP       │ │ • OTPSvc    │ │ • Data Transfer         │ │ │
│ │ │ • WebAuthn  │ │ • Repos     │ │ • Validation            │ │ │
│ │ └─────────────┘ └─────────────┘ └─────────────────────────┘ │ │
│ └─────────────────────────────────────────────────────────────┘ │
│                              │                                 │
│ ┌─────────────────────────────────────────────────────────────┐ │
│ │            infrastructure/ (Infrastructure Layer)          │ │
│ │ ┌─────────┐ ┌─────────┐ ┌─────────┐ ┌─────────────────────┐ │ │
│ │ │ crypto/ │ │ totp/   │ │webauthn/│ │     database/       │ │ │
│ │ │ • AES   │ │ • TOTP  │ │ • PRF   │ │ • PostgreSQL        │ │ │
│ │ │ • HKDF  │ │ • Codes │ │ • Auth  │ │ • SQLC Queries      │ │ │
│ │ └─────────┘ └─────────┘ └─────────┘ │ • Repositories      │ │ │
│ │                                     │ • Migrations        │ │ │
│ │                                     └─────────────────────┘ │ │
│ └─────────────────────────────────────────────────────────────┘ │
└─────────────────────────────────────────────────────────────────┘
                              │
                              ▼
                   ┌─────────────────┐
                   │   PostgreSQL    │
                   │ • Encrypted     │
                   │   TOTP Secrets  │
                   │ • User Data     │
                   │ • Credentials   │
                   └─────────────────┘

Clean Architecture Benefits ✅

• Testability: All dependencies injected via interfaces
• Maintainability: Clear separation of concerns
• Scalability: Easy to add new features without coupling
• Security: Domain layer enforces business rules
• Flexibility: Easy to swap implementations (database, crypto, etc.)

🔒 Enhanced Security Model (Phase 3)

Zero-Knowledge Encryption Flow

1. User Authentication
   OAuth (Google) → JWT Token → User Session

2. WebAuthn Setup  
   User registers biometric/security key → PRF Extension Detection

3. Enhanced Key Derivation (PRF-First)
   ┌─ PRF Available? ─┐
   │                  │
   ▼ YES              ▼ NO
   PRF → HKDF         credential.id → PBKDF2
   │                  │
   └─ AES-256-GCM ←───┘

4. Client-Side Encryption
   TOTP Secret → AES Encrypt → "ciphertext.iv.authTag"

5. Secure Storage
   Server stores encrypted data only (never plaintext)

6. Client-Side TOTP Generation
   Decrypt secret → Generate codes with otpauth library

Security Guarantees ✅

• Zero-Knowledge: Server cannot decrypt user data under any circumstances
• PRF Security: Hardware-backed key derivation when available
• Universal Compatibility: Works with all WebAuthn devices
• Perfect Forward Secrecy: Session keys not stored persistently
• Tamper Detection: GCM authentication prevents data modification
• Audit Trail: All security events logged

🛠️ Technology Stack

Frontend (Client-Side)

• React 18 with TypeScript for type safety
• HeroUI for beautiful, accessible UI components
• TanStack Query for server state management and caching
• Zustand for client-side state management
• OTPAuth for industry-standard TOTP code generation
• WebAuthn API with PRF extension support
• Vite for fast development and optimized builds

Backend (Server-Side)

• Go 1.22+ with clean architecture principles
• Gin web framework with comprehensive middleware
• PostgreSQL 15+ with SQLC for type-safe database operations
• WebAuthn PRF for enhanced hardware-backed security
• OAuth 2.0 (Google) for user authentication
• JWT for secure session management
• HKDF (RFC 5869) for cryptographic key derivation
• AES-256-GCM for authenticated encryption

Infrastructure

• Docker and Docker Compose for development and deployment
• PostgreSQL for secure data persistence
• Gin middleware for CORS, security headers, logging
• SQLC for compile-time SQL validation
• Goose for database migrations

📊 Implementation Status

✅ Completed Features (Phase 1-3)

• Clean Architecture: Domain-driven design with proper layer separation
• OAuth Authentication: Google OAuth 2.0 with JWT session management
• WebAuthn PRF: Enhanced hardware-backed key derivation
• Fallback Compatibility: Universal support for all WebAuthn devices
• Zero-Knowledge E2E Encryption: Client-side AES-256-GCM encryption
• TOTP Management: Full CRUD operations with secure storage
• Real-Time TOTP Generation: Client-side code generation with progress indicators
• Beautiful Frontend: Modern React SPA with HeroUI components
• Database Layer: PostgreSQL with SQLC type-safe queries
• RESTful API: Comprehensive API with error handling and validation
• Security: Multiple layers of protection with audit logging
• Development Tools: Complete development workflow with Docker

🔧 Current Limitations (Pre-Production)

• Single OAuth Provider: Only Google OAuth implemented
• Browser-Only: No mobile app or browser extension
• No Multi-Device Sync: Single device limitation (Phase 4 requirement)
• No Backup/Recovery: Manual backup not yet implemented (Phase 4 requirement)
• Development Security: Not hardened for production deployment
• No Rate Limiting: Production-grade rate limiting not implemented
• No Monitoring: Production monitoring and alerting not configured

🚧 Phase 4 Required for Production

• Multi-Device Synchronization: Encrypted sync across devices with PRF support
• Backup & Recovery: Secure backup codes and recovery mechanisms
• Security Audit: Comprehensive penetration testing and hardening
• Performance Optimization: Caching, rate limiting, optimization
• Production Monitoring: Health checks, alerting, and observability
• Production Deployment: Production-ready configurations and automation

📚 Documentation

Core Documentation

• Server README - Backend implementation details
• Implementation Roadmap - Phase-by-phase development
• API Documentation - Complete API reference
• Deployment Guide - Production deployment instructions

Design Documentation

• System Architecture - Clean architecture deep dive
• Cryptographic Design - PRF and encryption details
• Database Schema - Database design and relationships
• API Design - RESTful API design principles

Project Documentation

• Features Overview - Complete feature list and status
• Documentation Updates - Change log

🚀 Development

Quick Development Setup

# 1. Start database
cd server && make db-up

# 2. Start backend (Terminal 1)
make run

# 3. Start frontend (Terminal 2)  
cd ../client && yarn dev

# Access application
# Frontend: http://localhost:5173
# Backend API: http://localhost:8080
# Health Check: http://localhost:8080/health

Available Commands

Backend (server/)

make help           # Show all available commands
make build          # Build the application  
make run            # Run the application
make test           # Run all tests
make test-cover     # Run tests with coverage
make generate       # Generate SQLC code
make db-up          # Start database services
make db-down        # Stop database services
make lint           # Run linter
make fmt            # Format code

Frontend (client/)

yarn dev            # Start development server
yarn build          # Build for production
yarn test           # Run tests
yarn lint           # Run ESLint
yarn type-check     # TypeScript type checking

🧪 Testing

Backend Testing

cd server

# Run all tests
make test

# Run tests with coverage
make test-cover

# Run specific test packages
go test ./internal/application/usecases/...
go test ./internal/infrastructure/crypto/...

Frontend Testing

cd client

# Run all tests
yarn test

# Run tests in watch mode
yarn test:watch

# Run tests with coverage
yarn test:coverage

🐳 Deployment

Development

Use Docker Compose for the complete development environment:

cd server
make docker-run

Production

See Deployment Guide for production setup including:

• Docker production configurations
• Environment variable security
• Nginx reverse proxy setup
• SSL/TLS certificate configuration
• Database backup and monitoring strategies

🤝 Contributing

We welcome contributions! Please follow these guidelines:

Development Standards

• Clean Architecture: Follow the established layer patterns
• Go Code: Use gofmt, golint, and follow Go best practices
• TypeScript: Strict type checking and ESLint compliance
• Testing: Write tests for new functionality
• Documentation: Update docs for new features

Contribution Process

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Make your changes with tests
4. Ensure all tests pass (make test in both server/ and client/)
5. Update documentation as needed
6. Submit a pull request

📜 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• WebAuthn Community for passwordless authentication standards and PRF extension
• OTPAuth Library for robust client-side TOTP implementation
• HeroUI Team for beautiful and accessible React components
• Go Community for excellent tooling, libraries, and clean architecture patterns
• Clean Architecture principles by Robert C. Martin (Uncle Bob)

📞 Support

• Issues: GitHub Issues
• Discussions: GitHub Discussions
• Security: For security issues, please email security@yourdomain.com

⭐ How It Works (Technical Summary)

2FAir implements a true zero-knowledge architecture with clean architecture principles:

1. Clean Layer Separation: Domain → Application → Infrastructure → Interface layers
2. User Authentication: OAuth 2.0 creates secure user sessions
3. WebAuthn Setup: Hardware security key registration with PRF detection
4. Enhanced Key Derivation: PRF → HKDF → AES key (preferred) or credential.id → PBKDF2 (fallback)
5. Client-Side Encryption: TOTP secrets encrypted with AES-256-GCM before transmission
6. Secure Storage: Server stores only encrypted ciphertext.iv.authTag data
7. Code Generation: Client decrypts secrets and generates TOTP codes using otpauth
8. Session Management: Encryption keys cached in memory for seamless UX

The server never sees your TOTP secrets or codes in plaintext, with best-in-class security when your device supports PRF, all built on a maintainable clean architecture foundation!

⚠️ Development Status: Core features complete but Phase 4 required for production deployment.

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Phase 3 Complete ✅ - Clean Architecture + PRF Implementation
Phase 4 Required 🚧 - Multi-Device Sync & Production Hardening for Production Readiness