PolyBid 🔐

Privacy-Preserving Sealed-Bid Auctions on Blockchain

Built with Zama's fhEVM

🎯 The Problem

Traditional blockchain auctions suffer from critical privacy issues:

Front-running: Bots can see pending bids and outbid users
Bid sniping: Last-second bids exploit transparent bid amounts
Privacy leaks: All losing bids are permanently visible on-chain
Trust issues: Users must trust centralized platforms for sealed-bid auctions

💡 Our Solution

PolyBid leverages Fully Homomorphic Encryption (FHE) to create truly private, trustless sealed-bid auctions directly on the blockchain. Bid amounts remain encrypted throughout the entire auction lifecycle, with the smart contract computing the winner without ever decrypting losing bids.

Key Innovation

Unlike commit-reveal schemes or zero-knowledge proofs, FHE allows:

✅ Real-time bid validation (opening price checks) on encrypted values
✅ On-chain winner determination without revealing any bid amounts
✅ Permanent privacy for losing bidders (no reveal phase needed)
✅ Trustless execution with no centralized components

🏗️ Architecture

Smart Contract Layer (Solidity + fhEVM)

┌─────────────────────────────────────────────────────────┐
│                   AuctionFactory.sol                    │
│  • Creates new Auction contracts (Factory Pattern)      │
│  • Stores auction metadata (IPFS images, descriptions)  │
│  • Tracks all deployed auctions                         │
└─────────────────────────────────────────────────────────┘
                            │
                            │ deploys
                            ▼
┌─────────────────────────────────────────────────────────┐
│                      Auction.sol                        │
│                                                         │
│  FHE Operations:                                        │
│  • submitBid(euint64 encryptedBid) - Store encrypted    │
│  • TFHE.max(bid1, bid2) - Compare without decryption   │
│  • amITheWinner() → ebool - Private winner check        │
│                                                         │
│  Privacy Features:                                      │
│  • ACL (Access Control Lists) for encrypted data        │
│  • Only bidder can decrypt their own bid status         │
│  • Winner revealed only after auction closes            │
└─────────────────────────────────────────────────────────┘

Frontend Layer (React + Viem + Zama SDK)

User Input (plaintext bid)
         │
         ▼
┌─────────────────────────┐
│  Zama FHE SDK           │
│  • Client-side encrypt  │
│  • Generate proof       │
└─────────────────────────┘
         │
         ▼
    euint64 + proof
         │
         ▼
┌─────────────────────────┐
│  Smart Contract         │
│  • Validate proof       │
│  • Store encrypted bid  │
│  • Compare with TFHE    │
└─────────────────────────┘

✨ Features

🔒 Privacy-First Design

Encrypted Bidding: All bid amounts encrypted client-side using Zama's FHE SDK
Anonymous Identities: Wallet addresses displayed as "Anon-XXXX" throughout the UI
Private Winner Checks: Users can verify if they won without revealing their bid
No Reveal Phase: Losing bids remain encrypted forever

🎨 Premium User Experience

Responsive Design: Mobile-first UI with TailwindCSS
Gmail-Style FAB: Floating Action Button for quick auction creation
Real-time Updates: Live auction countdowns and bid notifications
Smooth Animations: Framer Motion for polished interactions
IPFS Integration: Decentralized image storage via Pinata

🛡️ Security & Validation

Opening Price Enforcement: Bids validated against minimum price (encrypted)
Deposit Locking: Bid amounts locked until auction closes
Network Guards: Auto-switch to Sepolia testnet
Input Sanitization: XSS protection and address validation
Error Handling: User-friendly error messages for all edge cases

📊 Comprehensive Profile Dashboard

Selling Tab: Track auctions you've created (Active/Pending/Ended)
Buying Tab: Monitor your bids and check win status
Wallet Integration: RainbowKit for seamless wallet connection
Transaction History: Complete audit trail of all actions

🚀 Live Demo

Deployed on Sepolia Testnet

Frontend: https://poly-bid.vercel.app/
Factory Contract: 0x4168574D678D9f54C0B5FF7ddE388aF772310330
Network: Sepolia (Chain ID: 11155111)

Quick Start (Local)

# Clone the repository
git clone https://github.com/Admuad/PolyBid.git
cd PolyBid

# Install dependencies
cd frontend && npm install
cd ../contracts && npm install

# Configure environment
cp frontend/.env.example frontend/.env.local
# Add your WalletConnect Project ID and Pinata keys

# Run frontend
cd frontend && npm run dev

Visit http://localhost:5173 and connect your wallet!

🧪 Testing

Smart Contract Tests

cd contracts
npm test

Test Coverage:

✅ Auction creation with opening price
✅ Encrypted bid submission and validation
✅ Winner determination using FHE comparisons
✅ ACL permissions for encrypted data
✅ Refund and withdrawal mechanisms
✅ Edge cases (zero bids, expired auctions, etc.)

Frontend Testing

cd frontend
npm run lint
npm run build  # Validates TypeScript compilation

Manual Testing Checklist:

✅ Create auction with IPFS image upload
✅ Submit encrypted bid above opening price
✅ Update bid (increase amount)
✅ Close auction and reveal winner
✅ Check win status (FHE decryption)
✅ Claim refund (losing bidders)
✅ Withdraw proceeds (seller)
✅ Mobile responsiveness (all breakpoints)

📖 How It Works

1️⃣ Create Auction

Seller creates an auction with:

Item name, description, and image (stored on IPFS)
Duration (minutes/hours/days)
Opening price (minimum bid)
0.0001 ETH deposit (reward for auction closer)

2️⃣ Submit Encrypted Bids

Bidders:

Enter bid amount in the UI
Frontend encrypts the bid using Zama's FHE SDK
Smart contract validates: encryptedBid >= encryptedOpeningPrice
Bid amount locked as deposit

3️⃣ Close Auction

Anyone can close an expired auction:

Contract computes maxBid = TFHE.max(bid1, bid2, ...)
Winner determined without decrypting any bids
Closer receives 0.0001 ETH reward

4️⃣ Claim Funds

Winner: Contacts seller to arrange item transfer
Losers: Withdraw their bid deposits (refunds)
Seller: Withdraws winning bid amount

🎓 Technical Deep Dive

FHE Implementation Details

Encrypted Bid Storage:

mapping(address => euint64) private bids;  // Encrypted bid amounts
mapping(address => bool) public hasBid;    // Public participation flag

Encrypted Comparison:

function submitBid(einput encryptedAmount, bytes calldata inputProof) external payable {
    euint64 bid = TFHE.asEuint64(encryptedAmount, inputProof);
    
    // Compare encrypted bid with encrypted opening price
    ebool isValid = TFHE.ge(bid, openingPrice);
    require(TFHE.decrypt(isValid), "Bid below opening price");
    
    bids[msg.sender] = bid;
    TFHE.allow(bid, msg.sender);  // ACL: bidder can decrypt their own bid
}

Winner Determination:

function closeAuction() external {
    euint64 maxBid = bids[bidders[0]];
    
    for (uint i = 1; i < bidders.length; i++) {
        maxBid = TFHE.max(maxBid, bids[bidders[i]]);
    }
    
    // Winner is determined, but maxBid value remains encrypted!
}

Why This Matters

Traditional sealed-bid auctions require a reveal phase, exposing all bids. PolyBid's FHE approach:

Eliminates reveal phase entirely
Protects bidder privacy permanently
Enables trustless on-chain execution
Prevents collusion and manipulation

🛠️ Tech Stack

Layer	Technology	Purpose
Smart Contracts	Solidity 0.8.28	Core auction logic
	Zama fhEVM	Encrypted computation
	Hardhat	Development & testing
Frontend	React 18 + TypeScript	UI framework
	Vite	Build tool
	TailwindCSS	Styling
	Wagmi v2 + Viem	Blockchain interaction
	RainbowKit	Wallet connection
	Framer Motion	Animations
Storage	IPFS (Pinata)	Decentralized images
Network	Sepolia Testnet	Deployment

🎯 Zama Developer Program Alignment

✅ Baseline Requirements (50%)

Original Tech Architecture (35%)

Custom factory pattern for scalable auction deployment
Unique FHE integration: encrypted opening price validation
Novel ACL usage for privacy-preserving winner checks
Not boilerplate - built from scratch with Zama primitives

Working Demo Deployment (15%)

Live deployment on Sepolia testnet
Fully functional end-to-end flow
IPFS integration for production-ready UX

✅ Quality & Completeness (30%)

Testing (10%)

Comprehensive Hardhat test suite
Manual testing checklist (documented above)
Edge case coverage (zero bids, expired auctions, etc.)

UI/UX Design (10%)

Premium, modern interface with dark mode
Mobile-responsive (tested on all breakpoints)
Intuitive user flows with helpful error messages
Smooth animations and loading states

Presentation Video (10%)

Watch the Demo Video
Walkthrough of create → bid → close → claim flow
Explanation of FHE privacy benefits

✅ Differentiators (20%)

Development Effort (10%)

7 development phases completed (see task.md)
50+ components and hooks
Comprehensive error handling and validation
Production-ready code quality

Business Potential (10%)

Target Market: NFT auctions, real estate, procurement
Competitive Advantage: Only truly private on-chain auctions
Scalability: Factory pattern enables unlimited auctions
Monetization: Transaction fees, premium features
Roadmap: Multi-chain deployment, DAO governance, advanced auction types

🗺️ Roadmap

Phase 1: Core Platform ✅

FHE-encrypted bidding
Factory pattern deployment
Profile dashboard
IPFS integration

Phase 2: Advanced Features 🚧

Dutch auctions (descending price)
Multi-item auctions (batch bidding)
Auction templates (NFTs, real estate, etc.)
Reputation system

Phase 3: Ecosystem Growth 📅

Multi-chain deployment (Polygon, Arbitrum)
DAO governance for platform fees
Mobile app (React Native)
API for third-party integrations

🤝 Contributing

We welcome contributions! Please see our Contributing Guidelines.

Development Setup

# Install dependencies
npm install

# Run tests
cd contracts && npm test

# Start local dev server
cd frontend && npm run dev

# Lint code
npm run lint

📄 License

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

🙏 Acknowledgments

Zama for pioneering FHE technology and the fhEVM
Polynomial for the branding inspiration
Sepolia Testnet for reliable testing infrastructure
Zama Developer Program for the opportunity to build confidential dApps

📞 Contact

X: @Adedir2
GitHub: @Admuad
Project: PolyBid Repository
Discord: Join the Zama Discord and find me in #developer-program

Built with 💚 using Zama's FHE technology
Making blockchain auctions private, fair, and trustless

Name		Name	Last commit message	Last commit date
Latest commit History 17 Commits
.github		.github
Zama		Zama
contracts		contracts
docs		docs
frontend		frontend
scripts		scripts
.gitignore		.gitignore
Protocol.pdf		Protocol.pdf
QUICKSTART.md		QUICKSTART.md
QUICK_REFERENCE.md		QUICK_REFERENCE.md
README.md		README.md
SUMMARY.md		SUMMARY.md
ZAMA_UPDATES.md		ZAMA_UPDATES.md
package-lock.json		package-lock.json
package.json		package.json
vercel.json		vercel.json

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