- CRYPTOCURRENCY
-
by admin
Verifying ERC20 Transfer Events in L1: A Stability Example
In this article, we will explore how to verify an ERC20 transfer event on the Ethereum Layer 2 (L2) network using a Solidity smart contract. We will assume that Alice transferred 100 USDC to Bob B in block transaction T.
Problem: L1 – Ethical Transactions in L2
When transferring assets between different blockchains, such as from L1 to L2, the transaction is executed on L1 and then propagated to L2 through a series of Etherscan transactions. However, this process can be inefficient due to network latency and gas costs.
The ERC20 standard, which governs the transfer of tokens between accounts, has been updated to include support for L1-ETH transfers. However, verifying these events remains a challenge due to the decentralized nature of blockchain networks.
Our Solution: A Stability Contract
We will create a simple smart contract in Solidity that demonstrates how to verify an ERC20 transfer event on L1 using an L2 network (Arbitrum One or Optimism). The contract will track all transactions involving Bob and identify those transactions with specific conditions, such as the sender is Alice and the recipient has transferred 100 USDC.
pragma solidity ^0,8,0;
import "
contract L1ToL2Verifier {
// Mapping accounts to their transaction history
mapping(address => TransactionHistory) public Transactions;
struct TransactionHistory {
uint256 blockNumber;
address fromAddress;
address toAddress;
uint256 amount;
}
event TransactionCreated(address indexed sender, address indexed recipient, uint256 amount);
event TransferEvent(address indexed from, address indexed to, uint256 amount);
function createTransactionHistory() public net return (TransactionHistory) {
return TransactionHistory(block.timestamp, msg.sender, 0, 100 10*18);
}
function sendTransaction(address _recipient, uint256 _amount) public payable {
// Create transaction history for sender
transactions[message.sender].blocknumber = blocknumber;
transactions[message.sender].fromAddress = _recipient;
// Update recipient transaction history
transactions[_recipient].amount += _amount;
}
function verifyTransactionEvent(address _sender, address _recipient) public returns (bool) {
// Get the sender and recipient of the transfer from the L1 account history
TransactionHistory sender = transactions[msg.sender];
TransactionHistory recipient = transactions[_recipient];
// Check if the sender is Alice
request(sender.fromAddress == "0x..." , "Invalid sender");
// Check if the recipient has transferred 100 USDC
request(recipient.amount >= 100 10*18, "Recipient did not transfer enough tokens");
// Create a new event for the transfer event (not shown in this example)
emit TransferEvent(sender.fromAddress, _recipient, 100 10*18);
return true;
}
}
Explanation
This Solidity contract consists of three main functions:
createTransactionHistory: Creates a new transaction history for an account.
- SendTransaction: Sends a transaction from one address to another and updates its transaction history.
- VerifyTransactionEvent: Verifies that a specific transfer event has occurred on the L1 network (Ethereum) using the specified sender and receiver addresses.
The contract uses a mapping to store all transactions associated with Bob, including his transaction history.
Deployment
To deploy this contract, you will need to:
- Set up an Ethereum faucet account.
2.
