Account Abstraction simplifies blockchain interactions by allowing smart contracts to serve as user accounts, merging contract capabilities with account management. The Titan upgrade opens the door for Account Abstraction to become reality on Cronos Testnet.
Account Abstraction opens up possibilities for numerous use cases such as multi-signature transactions, social recovery, contract whitelisting, custom gas tokens, subsidizing gas fees, and much more. It expands the use-case potential of DApps and enables a more intuitive user experience.
Key components are provided to support Account Abstraction development:
User Operations: A new transaction object type that includes additional data, allowing for custom transaction and security configurations.
JSON-RPC API debug_traceCall: Enables simulation of User Operations before they are executed on-chain.
Bundlers: Crucial nodes that bundle unsigned User Operations into a single package for signing and subsequent publication on the mainnet. Bundlers estimate transaction fees.
Entry Point Contract: an audited and trusted singleton contract, is functional and can process the execution and validating User Operations.
Account Abstraction is natively supported on Cronos, and developers can leverage these features for their own use cases. There are also application-level account abstraction solutions available for developers who need Account Abstraction functionality now, such as . Please contact if you would like to be introduced to the relevant developer tool platforms.
Send a UserOperation using userop.js
In this guide, we will go through how to send a userop transaction with subsidized gas fee.
Here we are using to send UserOperations but you can use any library you like, even using curl .
We will create a new project for sending transactions
import { ethers,Wallet,Contract } from "ethers";
import { Presets,Client } from "userop";
import { config } from "dotenv";
config();
const NODE_RPC_URL = process.env.NODE_RPC_URL;
const BUNDLER_RPC_URL = process.env.BUNDLER_RPC_URL;
const SIGNER_PKEY = process.env.SIGNER_PKEY;
const ENTRY_POINTS = process.env.ENTRY_POINTS;
const ACCOUNT_FACTORY = process.env.ACCOUNT_FACTORY;
async function main() {
// signer is the owner of the smart account
const signer = new ethers.Wallet(SIGNER_PKEY)
// Initialize userop builder
var builder = await Presets.Builder.SimpleAccount.init(
signer,
NODE_RPC_URL,
{
overrideBundlerRpc: BUNDLER_RPC_URL,
entryPoint: ENTRY_POINTS,
factory: ACCOUNT_FACTORY,
}
);
// these two addresses are different
// need to fund the smart account before running this script
console.log(`Signer address: ${signer.address}`);
console.log(`Account address: ${builder.getSender()}`);
// build a tranfer transaction
builder = builder
.execute(
"0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266",
"100",
ethers.utils.hexlify("0x")
)
// create the client
const client = await Client.init(
NODE_RPC_URL,
{
overrideBundlerRpc: BUNDLER_RPC_URL,
entryPoint: ENTRY_POINTS,
factory: ACCOUNT_FACTORY,
}
);
// send the useroperation to the bundler node
const res = await client.sendUserOperation(builder, {
onBuild: (op) => {
console.log("Signed UserOperation:",op);
},
});
console.log(`UserOpHash: ${res.userOpHash}`);
// !!! this step can get stuck in a local geth dev setup
// because the bundler node is waiting for new block event to bundle the userops
// try to send a new tx in the local geth dev setup to trigger bundle
console.log("Waiting for transaction...");
const ev = await res.wait();
console.log(`Transaction hash: ${ev?.transactionHash ?? null}`);
}
main().then();
If successful, you will see the above logs including transaction hash and userOpHash printed out.
We can now verify with this tx hash on the block explorer, that we have successfully sent out a TX, and the gas fees were funded by the account address 0x6813Eb9362372EE...19671cBA69.
