# 📋 Implementation Summary

## What We've Built

✅ **Complete Passkey Authentication System** with email-based access control
✅ **SQLite Database** for persistent user storage
✅ **Email Allowlist System** for controlling who can register
✅ **Kubernetes Integration** with nginx ingress auth backend
✅ **Modern Web UI** for user registration and management
✅ **Production-Ready Deployment** with Docker and Kubernetes manifests

## Key Features Implemented

### 🔐 Email-Based Authentication
- Users are identified by email addresses (not usernames)
- Configurable email allowlist for access control
- Environment variable support for email configuration

### 📧 Email Access Control Options

1. **Open Mode**: Empty allowlist allows any email
2. **Restricted Mode**: Only allowlisted emails can register
3. **Combined Security**: Allowlist + manual approval

### 🗄️ Database Architecture (SQLite)
```sql
-- Users table
CREATE TABLE users (
    id INTEGER PRIMARY KEY,
    email TEXT UNIQUE NOT NULL,     -- Email as primary identifier
    display_name TEXT NOT NULL,
    approved BOOLEAN DEFAULT FALSE,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
);

-- Credentials table (WebAuthn keys)
CREATE TABLE credentials (
    id BLOB PRIMARY KEY,
    user_id INTEGER REFERENCES users(id),
    public_key BLOB NOT NULL,
    attestation_type TEXT NOT NULL,
    aaguid BLOB,
    sign_count INTEGER DEFAULT 0,
    clone_warning BOOLEAN DEFAULT FALSE,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
);
```

### ⚙️ Configuration Options

```yaml
auth:
  session_secret: "your-secret-key"
  require_approval: true           # Admin approval required
  allowed_emails:                  # Email allowlist
    - "admin@company.com"
    - "engineering@company.com"
```

Or via environment variables:
```bash
export ALLOWED_EMAILS="admin@company.com,user1@company.com,user2@company.com"
export SESSION_SECRET="your-secure-session-secret"
```

## Files Created/Modified

### Core Application
- `main.go` - Application entry point
- `internal/config/` - Configuration management with email allowlist
- `internal/database/` - SQLite database layer with email-based users
- `internal/auth/` - WebAuthn implementation
- `internal/handlers/` - HTTP handlers with email validation

### Web Interface
- `web/index.html` - Admin UI updated for email addresses

### Deployment
- `Dockerfile` - Container build
- `k8s/` - Kubernetes manifests
- `docker-compose.yml` - Local development
- `scripts/` - Build and deployment scripts

### Documentation
- `README.md` - Complete usage guide
- `PRODUCTION.md` - Production deployment guide
- `config.example.yaml` - Example configuration

## How It Works

1. **Email Validation**: When a user tries to register, the system checks if their email is in the allowlist (if configured)
2. **Database Storage**: User data is stored in SQLite with email as the unique identifier
3. **WebAuthn Integration**: Passkey credentials are linked to the user record
4. **Session Management**: Authentication sessions use email-based identification
5. **Nginx Integration**: Auth headers include user email for downstream applications

## Quick Start

```bash
# 1. Configure email allowlist
vim config.yaml  # Add your allowed emails

# 2. Start the service
./scripts/dev.sh

# 3. Register users at http://localhost:8080
# Only emails in the allowlist can register

# 4. Deploy to Kubernetes
./scripts/build.sh
./scripts/deploy.sh
```

## Security Benefits

- **No passwords stored** - Only WebAuthn public keys
- **Email-based access control** - Restrict registration to specific domains/emails
- **Phishing resistant** - WebAuthn is tied to the domain
- **MFA built-in** - Passkeys require user presence and verification
- **Session security** - Secure cookie-based sessions

This implementation provides a complete, production-ready passkey authentication system with fine-grained email-based access control, perfect for enterprise environments where you need to restrict access to specific users.