EIP-7702 Sponsored Batched Transactions Demo

This project demonstrates how to use EIP-7702 to sponsor gas fees and collect funds from deposit wallets using sponsored transactions with batching support. The demo showcases a practical implementation of EIP-7702's account abstraction capabilities for efficient multi-wallet operations.

What is EIP-7702?

EIP-7702 introduces account abstraction by allowing externally owned accounts (EOAs) to temporarily delegate their execution to smart contract code during a transaction. This enables features like:

• Gas sponsorship: A different account can pay for transaction gas
• Batched operations: Execute multiple operations in a single transaction
• Enhanced security: Add custom logic to EOA transactions

Project Overview

This demo includes:

• Smart Contracts:

  • Wallet.sol: A simple wallet contract that can be delegated to EOAs via EIP-7702
  • Batcher.sol: A contract for executing multiple calls in a single transaction
  • TestCoin.sol: An ERC-20 token for testing transfers

• TypeScript Scripts:

  • Deployment scripts for all contracts
  • Fund distribution script for test wallets
  • Main demo script showcasing sponsored batched transactions

• Key Features:

  • Gas sponsorship using EIP-7702 authorization lists
  • Batched token transfers from multiple wallets
  • Hardhat 3 Beta integration with viem for EIP-7702 support

How It Works

1. Authorization: Child wallets sign EIP-7702 authorization messages to delegate execution to the Wallet contract
2. Batching: The Batcher contract receives multiple calls and executes them sequentially
3. Sponsorship: A sponsor account pays gas for the entire batch transaction
4. Execution: Token transfers are executed from multiple child wallets in a single sponsored transaction

Live Demo on Optimism

Deployed Contracts

The following contracts have been deployed on Optimism mainnet:

• TestCoin (ERC-20): 0xA8C14b02CCa34f3595161CeA593B291009038426
• Wallet Contract: 0x3BF35243aE319B3be9649f707eaB23E1502F2E27
• Batcher Contract: 0x837F465302D425E9cF22b986c8DCeB2542f68159

Example Transaction

You can see a live example of the sponsored batched transaction on Optimism:

Transaction Hash: 0x785397663999b859ba443ce7c235cf06a13655d7fe290bce9c1f2215d56b7c92

This transaction demonstrates:

• EIP-7702 authorization delegation from multiple EOAs to the Wallet contract
• Sponsored gas payment by a single account
• Batched execution of token transfers from 5 different wallets
• All operations completed in a single transaction

Setup and Usage

Prerequisites

• Node.js (v18 or later)
• pnpm package manager
• An Ethereum network that supports EIP-7702 (e.g., local testnet, specific testnets)

Installation

pnpm install

Configuration

1. Set the TEST_MNEMONIC variable:

   pnpm hardhat keystore set TEST_MNEMONIC

   This will prompt you to enter your twelve word mnemonic phrase securely. This mnemonic will be used to generate the sponsor account and child wallets.

Deployment Steps

2. Deploy the TestCoin contract:

   pnpm run deployTestToken --network optimism

3. Deploy the Wallet contract:

   pnpm run deployWallet --network optimism

4. Deploy the Batcher contract:

   pnpm run deployBatcher --network optimism

Running the Demo

5. Fund the child wallets with test tokens:

   pnpm run sendTestCoin --network optimism

   This script will send 100 TestCoin tokens to each of the 5 child wallets.

6. Run the main demo:

   pnpm run demo --network optimism

   This will execute a sponsored batch transaction that transfers 5 tokens from each child wallet to a receiver, with all gas costs paid by the sponsor account.

Benefits Demonstrated

• Cost Efficiency: Single transaction for multiple operations reduces gas costs
• User Experience: Child wallets don't need ETH for gas
• Scalability: Batch operations scale better than individual transactions
• Flexibility: Sponsor can be any account, enabling various business models

Available Scripts

• pnpm run deployTestToken --network optimism - Deploy the TestCoin ERC-20 token contract
• pnpm run deployWallet --network optimism - Deploy the Wallet contract for EIP-7702 delegation
• pnpm run deployBatcher --network optimism - Deploy the Batcher contract for batched operations
• pnpm run sendTestCoin --network optimism - Distribute TestCoin tokens to child wallets
• pnpm run demo --network optimism - Execute the main sponsored batched transaction demo