Pocket Protocol – Cross-Chain Bridge Application

A cross-chain bridge enabling seamless token swaps between U2U Solaris Mainnet and Sepolia Testnet, built for the VietBUIDL Hackathon on HackQuest Demo.

🌉 Overview

Pocket Protocol is a cross-chain bridge application that enables users to swap tokens between U2U Solaris Mainnet and Sepolia Testnet. The application provides a user-friendly interface for cross-chain token transfers with real-time transaction tracking and automated relayer processing.

🔗 Supported Chains & Tokens

U2U Solaris Mainnet (Chain ID: 39)

• Native Token: U2U

• Explorer: https://u2uscan.xyz

• Bridge Contract: 0x20c452438968C942729D70035fF2dD86481F6EaB

Sepolia Testnet (Chain ID: 11155111)

• Native Token: ETH

• Explorer: https://sepolia.etherscan.io

• Bridge Contract: 0xe564df234366234b279c9a5d547c94AA4a5C08F3

• WETH Contract: 0x3BfA22D8b5fD0f63E96425717BC58910F4F7DD6D

🔄 Bridge Functionality

U2U → ETH Flow

1. User sends U2U to relayer address on U2U Solaris

2. Relayer receives U2U on U2U Solaris Mainnet

3. Relayer sends equivalent ETH to user on Sepolia Testnet

4. User receives ETH in their Sepolia wallet

ETH → U2U Flow

1. User sends ETH to relayer address on Sepolia

2. Relayer receives ETH on Sepolia Testnet

3. Relayer sends equivalent U2U to user on U2U Solaris

4. User receives U2U in their U2U wallet

ETH → WETH Bridge Flow

1. ETH locked in Sepolia bridge contract

2. Relayer mints WETH on U2U Solaris

3. User receives WETH in their U2U wallet

🏗️ Architecture

Frontend Components

• Swap Card: Main interface for cross-chain token swaps

• Bridge Card: Interface for ETH to WETH bridging

• Transaction Modal: Clean, modal-based progress tracking

• Relayer Liquidity: Real-time relayer balance monitoring

Smart Contracts

• U2UBridge.sol: Bridge contract deployed on U2U Solaris

• SepoliaBridge.sol: Bridge contract deployed on Sepolia

• WETH.sol: Wrapped ETH token contract on U2U Solaris

Backend Services

• Relayer API: Processes cross-chain transactions

• Price API: Provides swap quotes and exchange rates

• Status API: Monitors relayer health and liquidity

Relayer System

The relayer operates as a private-key-controlled liquidity hub that:

• Maintains balances on both chains

• Processes cross-chain transfers automatically

• Handles transaction verification and confirmation

• Provides real-time status updates

🚀 Getting Started

Prerequisites

• Node.js 18+

• MetaMask or compatible wallet

• Testnet tokens (U2U for U2U Solaris, ETH for Sepolia)

Installation

# Clone the repository
git clone https://github.com/manovHacksaw/pocket-protocol
cd pocket-protocol

# Install dependencies
npm install

# Set up environment variables
cp .env.example .env.local
# Add your configuration to .env.local

# Start development server
npm run dev

Usage

1. Connect Wallet: Connect your MetaMask wallet

2. Select Network: Switch to U2U Solaris or Sepolia

3. Choose Operation:

   • Use Swap Card for U2U ↔ ETH swaps

   • Use Bridge Card for ETH → WETH bridging

4. Enter Amount: Specify the amount to transfer

5. Confirm Transaction: Sign the transaction in your wallet

6. Track Progress: Monitor transaction progress in the modal

7. Receive Tokens: Tokens will appear in your target wallet

🎯 Key Features

User Experience

• Clean Modal Interface: Real-time transaction progress tracking

• Chain Validation: Automatic network switching prompts

• Liquidity Checking: Warns if relayer has insufficient funds

• Transaction Verification: Waits for blockchain confirmation

• Explorer Links: Direct links to view transactions on block explorers

Technical Features

• Wagmi Integration: Web3 wallet connection and transaction handling

• Viem: Low-level blockchain interaction

• Next.js 15: Modern React framework with App Router

• TypeScript: Type-safe development

• Tailwind CSS: Modern UI styling

⚠️ Important Disclaimers

Network Information

• U2U Solaris: This is a mainnet network

• Sepolia: This is a testnet network

Safety Notes

• Do not use real funds for this project unless officially provided by U2U for testing

• This is a hackathon demo - funds are not protected

• The relayer is centralized for demonstration purposes

• Not production-ready - use at your own risk

Current Limitations

• Single relayer wallet (centralized)

• No multi-signature protection

• Limited to testnet operations

• No insurance or fund protection

🔮 Future Development Ideas

Production Roadmap

• Multi-signature Relayer: Implement multi-sig wallet for enhanced security

• Decentralized Relayer Network: Multiple relayer nodes for redundancy

• On-chain Liquidity Pools: Replace single-key relayer with decentralized pools

• Real Mainnet Support: Support for real ETH and U2U transfers once audited

• Additional Chains: Expand to more blockchain networks

• Wrapped Token Support: Support for additional wrapped tokens

Security Enhancements

• Smart Contract Audits: Professional security audits

• Time-locked Operations: Implement time delays for large transfers

• Rate Limiting: Prevent abuse and ensure fair usage

• Emergency Pause: Circuit breakers for emergency situations

🛠️ Technical Stack

Frontend

• Next.js 15 with App Router

• TypeScript for type safety

• Tailwind CSS for styling

• Wagmi for Web3 integration

• Viem for blockchain interactions

Smart Contracts

• Solidity for contract development

• Hardhat for development and testing

• OpenZeppelin for security standards

Backend

• Node.js API server

• Express.js for API endpoints

• Web3.js for blockchain interactions

📊 Contract Addresses

🤝 Contributing

We welcome contributions! Please:

1. Fork the repository

2. Create a feature branch

3. Make your changes

4. Submit a pull request

📄 License

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

📞 Contact

• Hackathon: VietBUIDL Hackathon on HackQuest Demo

• Project: Pocket Protocol Cross-Chain Bridge

• Built with ❤️ for the U2U and Ethereum communities

⚠️ Disclaimer: This is a hackathon demonstration project. Do not use real funds unless officially provided for testing. The relayer system is centralized and not suitable for production use.