OptimismPay: Crypto Pay Master

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Introduction

OptimismPay is a groundbreaking project designed to revolutionize cross-chain transactions by:

• Eliminating the need for users to hold native tokens for gas.
• Ensuring privacy and security through Fully Homomorphic Encryption (FHE) powered by Zama FHEVM.
• Enabling seamless interoperability across networks in the Optimism Superchain.

By combining advanced encryption techniques, a modular SDK, and compatibility with the OP Stack, OptimismPay is a developer-friendly solution for wallets, dApps, and exchanges.

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Key Features

1. Gasless Experience:

   • Automatically deducts gas fees from the token being transferred, simplifying user interactions with blockchain networks.

2. Privacy-Preserving Transactions:

   • Utilizes Zama’s Fully Homomorphic Encryption (FHE) to encrypt sensitive transaction details, ensuring they remain private throughout the transfer process.

3. Cross-Chain Interoperability:

   • Built on the L2StandardBridgeInterop, enabling seamless token transfers across networks in the Optimism Superchain (e.g., Optimism, Base, Sepolia).

4. Developer-Friendly SDK:

   • A TypeScript-based SDK simplifies integration with wallets and dApps by abstracting contract interactions.

5. Modular Architecture:

   • Composed of reusable components, including gas management, encryption layers, and token validation.

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Problem Statement

Transacting across multiple blockchain networks often requires users to hold native tokens to pay gas fees. This creates several challenges:

• New Users: Frustration due to insufficient gas tokens.
• Accessibility: Limited on-ramps for acquiring native tokens in certain regions.
• Fragmentation: Unused native tokens accumulating across different networks.

OptimismPay solves these problems by enabling users to pay gas fees directly from the token being transferred, providing a seamless, gasless, and private cross-chain experience.

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How It Works

The system combines multiple smart contracts and Zama’s FHE to ensure private, gasless, and cross-chain token transfers.

Flow Diagram

graph TD
    A[User Initiates Transfer] -->|Sender, Receiver, Token, Amount| B[OptimismPay SDK]
    B --> C[PrivacyLayer: Encrypt Transaction Data]
    C -->|Encrypted Data| D[GasPaymaster: Calculate and Deduct Gas]
    D -->|Net Amount| E[OptimismPayBridge]
    E -->|Call L2StandardBridge| F[L2StandardBridge: Cross-Chain Transfer]
    F -->|Send Encrypted Data to Destination| G[OptimismPayBridge_Destination]
    G -->|Decrypt Transaction Data with PrivacyLayer| H[Finalize Transfer]
    H -->|Release Tokens to Receiver| I[Receiver Wallet]

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Workflow Breakdown

1. Privacy Preservation:
   • Sensitive transaction data is encrypted on-chain using Zama's FHE before transfer initiation.
2. Gas Fee Deduction:
   • The GasPaymaster contract dynamically calculates and deducts gas fees from the user's token balance.
3. Cross-Chain Messaging:
   • The OptimismPayBridge contract interacts with the L2StandardBridge to handle token and encrypted data transfers.
4. Decryption and Finalization:
   • On the destination chain, encrypted data is decrypted to finalize the transfer securely.

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Project Structure

The OptimismPay project is organized as a monorepo for better modularity and scalability.

📦 optimismpay-monorepo
├── 📁 apps
│   ├── 📁 frontend       # Demo wallet interface (Next.js)
│   ├── 📁 backend        # API for managing transactions (Node.js)
├── 📁 packages
│   ├── 📁 contracts      # Smart contracts and deployment scripts (Hardhat)
│   │   ├── ConfigManager.sol
│   │   ├── GasPaymaster.sol
│   │   ├── OptimismPayBridge.sol
│   │   └── PrivacyLayer.sol
│   ├── 📁 sdk            # Developer SDK for interacting with the system (TypeScript)
│   │   ├── integrations
│   │   │   ├── dAppAPI.ts       # APIs for dApp integrations
│   │   │   └── walletAPI.ts     # APIs for wallet integrations
│   │   ├── encryption
│   │   │   ├── fheEncrypt.ts    # Zama FHE encryption utilities
│   │   │   └── fheDecrypt.ts    # Zama FHE decryption utilities
│   │   └── utils
│   │       ├── networkUtils.ts  # Network utilities for fetching gas prices
│   │       └── tokenUtils.ts    # Token validation utilities
│   ├── 📁 shared         # Shared constants, types, and helpers
├── turbo.json            # TurboRepo configuration for monorepo management
├── pnpm-workspace.yaml   # Workspace configuration for pnpm
└── package.json          # Global dependencies and project metadata

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Installation

Prerequisites

• Node.js (v16+)
• pnpm for monorepo management
• Infura, Alchemy, or other RPC provider for network access

Steps

1. Clone the Repository:

   git clone https://github.com/AndreaDiazCorreia/Optimism-pay.git
   cd Optimism-pay

2. Install Dependencies:

   pnpm install

3. Set Up Environment Variables: Create a .env file in the root directory using the provided .env.example template.

4. Run the Development Environment:

   pnpm dev

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Testing

1. Unit Tests:

   pnpm test

2. Manual Testing: Deploy the contracts on testnets like Optimism Goerli or Sepolia and initiate transactions via the SDK.

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Roadmap

Phase 1: MVP Completion (Current Phase)

🟢 Cross-chain token transfers using Optimism's L2StandardBridge. 🟢 Privacy-preserving transactions with Zama FHE. 🟢 Initial SDK with core functionalities.

Phase 2: SDK Refinement

🟡 Enhanced API documentation and modularization. 🟡 Improved error handling and token validation logic.

Phase 3: Network Expansion

🟡 Add support for zkSync, Polygon Supernets, and other Superchain networks.

Phase 4: Advanced Privacy Features

🔵 Integrate zk-SNARKs for zero-knowledge transaction proofs.

Phase 5: Ecosystem Tools

🔵 Build browser extensions and plugins for ecommerce platforms.

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Acknowledgments

This project leverages the following technologies:

• Zama FHEVM: For privacy-preserving encryption and decryption.
• Optimism L2StandardBridge: For seamless cross-chain interoperability.
• Hardhat: For contract development and testing.
• TurboRepo: For efficient monorepo management.

Developed during the Aleph de Verano Hackathon 2024, the project aims to enhance blockchain accessibility and usability.

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License

This project is licensed under the MIT License.

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Contact

For questions or issues, open an issue on GitHub.

Social Media

Follow us on Social Media for updates and announcements.

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Happy Building 🚀!