Private-Input Sealed-Bid Auction System

A secure, web-based sealed-bid auction platform with private input encryption and real-time updates.

Features

• Private-Input Bidding: Bids are encrypted using AES-256 encryption with user-provided secret keys
• Real-time Updates: Live auction status and bid count updates using Socket.io
• Secure Authentication: User registration and login with bcrypt password hashing
• Responsive Design: Modern, mobile-friendly interface using Tailwind CSS
• Rate Limiting: Protection against brute force attacks and spam
• Auto-Closing: Auctions automatically close when their end time is reached

Security Features

• AES-256 Encryption: All bids are encrypted with user-provided secret keys
• Password Hashing: User passwords are hashed using bcrypt
• Rate Limiting: API endpoints are protected with rate limiting
• Input Validation: All user inputs are validated and sanitized
• Helmet.js: Security headers for web applications

Installation

1. Install dependencies:

npm install

2. Start the server:

npm start

For development with auto-reload:

npm run dev

3. Open your browser and navigate to http://localhost:3000

Usage

Creating an Account

1. Click the "Login" button in the header
2. Switch to "Register" mode
3. Enter a username and password
4. Click "Register"

Creating an Auction

1. Login to your account
2. Switch to the "Create Auction" tab
3. Fill in the auction details:
   • Title: Brief description of the item
   • Description: Detailed information about the item
   • Starting Bid: Minimum acceptable bid amount
   • End Time: When the auction should close
4. Click "Create Auction"

Placing a Sealed Bid

1. Browse active auctions in the "Auctions" tab
2. Click "Place Bid" on an auction you're interested in
3. Enter your bid amount
4. Create a secret key - this is crucial for bid verification
5. Save your secret key securely - you cannot recover it
6. Click "Place Bid"

Auction Results

• Auctions automatically close at their specified end time
• The highest bid wins
• Winners and winning amounts are displayed after auction closure

API Endpoints

Authentication

• POST /api/users/register - Register a new user
• POST /api/users/login - Login an existing user

Auctions

• GET /api/auctions - Get all auctions
• POST /api/auctions - Create a new auction
• GET /api/auctions/:id - Get specific auction details
• POST /api/auctions/:id/close - Close an auction manually

Bids

• POST /api/bids - Place a sealed bid

Security Considerations

Secret Key Management

• Secret keys are never stored on the server
• Users must save their secret keys securely
• Lost secret keys cannot be recovered
• Secret keys are required for bid verification (future enhancement)

Bid Privacy

• All bids are encrypted before storage
• Server cannot read bid amounts without the secret key
• Only bid counts and highest bid amounts are visible
• Individual bid amounts remain private until auction closure

Technical Architecture

Backend

• Node.js with Express.js
• Socket.io for real-time communication
• AES-256-CBC encryption for bid privacy
• bcrypt for password hashing
• Helmet.js for security headers
• express-rate-limit for API protection

Frontend

• Vanilla JavaScript (no framework dependencies)
• Tailwind CSS for styling
• Socket.io client for real-time updates
• Font Awesome for icons

Data Storage

• In-memory storage using JavaScript Maps
• Note: For production use, replace with a proper database (MongoDB, PostgreSQL, etc.)

Future Enhancements

• Bid Verification: Allow users to verify their bids using secret keys
• Database Integration: Replace in-memory storage with persistent database
• User Profiles: Enhanced user management and profiles
• Bid History: Detailed bid history and analytics
• Notifications: Email/SMS notifications for auction events
• Multi-item Auctions: Support for multiple items in a single auction
• Proxy Bidding: Automatic bidding up to a maximum amount

Development

Project Structure

sealed-bid-auction/
├── server.js              # Main server file
├── package.json           # Dependencies and scripts
├── public/
│   ├── index.html         # Main HTML file
│   └── app.js            # Frontend JavaScript
└── README.md              # This file

Testing

Run tests with:

npm test

License

MIT License - feel free to use this project for personal or commercial purposes.

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Submit a pull request

Support

For issues and questions, please create an issue in the project repository.