Meta Transactions

Overview

This project implements a meta-transaction-enabled NFT contract using ERC-2771. It uses a Trusted Forwarder to enable gasless transactions for end users. The project utilizes Hardhat Ignition for deploying and managing smart contracts.

Features

• ERC-2771 Meta Transactions: Enables gasless transactions using a forwarder contract.
• NFT Contract: Supports minting and transferring NFTs.
• EIP-712 Domain: Provides structured data signing for secure meta-transactions.

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Project Structure

Smart Contracts

1. TrustedForwarder: A contract that validates the meta-transaction requests.
2. MetaTxNFT: The main NFT contract that integrates with the Trusted Forwarder and inherits ERC2771Context.

Scripts and Utilities

1. Deployment Modules:

   • forwarder.js: Deploys the TrustedForwarder contract.
   • nft.js: Deploys the MetaTxNFT contract.

2. EIP-712 Utilities:

   • eip712.js: Provides utilities to generate domain types and hash typed data.
   • eip712-types.js: Defines schemas for EIP-712 structured data.

3. Helper Functions:

   • iterate.js: Provides utility functions for handling arrays and objects.

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Understanding ERC-2771

ERC-2771 is a standard for supporting meta-transactions on Ethereum. Meta-transactions allow a third party (known as a relayer) to pay for the gas fees on behalf of the end user. This approach is especially useful for enhancing user experience, as it enables gasless interactions with blockchain applications.

Key Components of ERC-2771:

1. Trusted Forwarder:

   • Acts as a middleman to validate and forward transactions on behalf of users.
   • Ensures that the transaction originates from a trusted relayer.

2. MetaTxNFT Contract:

   • Integrates with the Trusted Forwarder to process meta-transactions.
   • Validates the meta-transaction signature using the EIP-712 standard.

Benefits of ERC-2771:

• Improved User Experience: End users are not required to hold ETH for gas fees.
• Seamless Integration: Developers can integrate gasless transactions without significant changes to the existing contract logic.
• Security: Relayers are authenticated using signatures and domain separation, reducing the risk of malicious activities.

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Prerequisites

1. Node.js (>= 14.x)
2. Hardhat (latest version)
3. NPM or Yarn

Install dependencies by running:

npm install

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Deployment

This project uses Hardhat Ignition for deploying contracts.

Steps

1. Compile Contracts:

   npx hardhat compile

2. Deploy TrustedForwarder: Use the following command to deploy the TrustedForwarder contract:

   npx hardhat ignition deploy ./ignition/modules/forwarder.js --network polygonAmoy

3. Deploy MetaTxNFT: Update the nft.js module with the Trusted Forwarder's deployed address, then deploy the NFT contract:

   npx hardhat ignition deploy ./ignition/modules/nft.js --network polygonAmoy

4. Run Meta-Transaction Script: After deployment, use the following command to execute the ERC-2771 meta-transaction script:

   npx hardhat run scripts/ERC2771MetaTransaction.ts

Configuration

Update the constructor arguments in nft.js to include:

• FORWARDER_CONTRACT_ADDRESS: Address of the deployed Trusted Forwarder.
• MYNft: Name of your NFT.
• NFT_CONTRACT_OWNER: Address of the owner.

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Running Scripts

EIP-712 Domain Utilities

Generate the domain details for a contract:

node eip712.js

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Key Commands

Compile

npx hardhat compile

Deploy Contracts

npx hardhat ignition deploy --module <MODULE_FILE> --network <NETWORK_NAME>

Run Meta-Transaction Script

npx hardhat run scripts/ERC2771MetaTransaction.ts

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Additional Information

Libraries Used

• ethers.js: For interacting with Ethereum contracts.
• Hardhat Ignition: For managing complex deployment processes.

Notes

• Ensure you configure the hardhat.config.js file to include your network details.
• Double-check the deployment addresses in your nft.js and forwarder.js files.

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License

This project is licensed under the MIT License.