# Turnkey signer

[Turnkey](https://www.turnkey.com/) is a key infrastructure provider with a powerful developer API and a robust security policy engine, enabling secure and flexible key management for blockchain applications.

By integrating **Turnkey** with **Connect 4337**, you can create **custodial Account Abstraction (AA) wallets**, where Turnkey ensures the security of private keys while using **Cometh Connect’s smart wallets** to sponsor gas, batch transactions, and enhance overall dApp functionality.

#### **Setup**

To use **Turnkey** with **Connect 4337**, first create an application that integrates with Turnkey.

* Refer to the [Turnkey documentation site](https://docs.turnkey.com/) for instructions on setting up an application with the Turnkey.
* For a quick start, Turnkey provides examples, available [here](https://docs.turnkey.com/getting-started/examples).

## Integration

After following the Turnkey documentation, you will have access to a `TurnkeyClient` object as shown below that you can pass as an owner to `createSafeSmartAccount`:

```typescript
import { TurnkeyClient } from "@turnkey/http"
import { createAccount } from "@turnkey/viem"


// Param options here will be specific to your project.  See the Turnkey docs for more info.
const turnkeyClient = new TurnkeyClient({ baseUrl: "" }, stamper)
 
const turnkeySigner = await createAccount({
	client: turnkeyClient,
	organizationId: subOrganizationId, // Your subOrganization id
	signWith: signWith, // Your suborganization `signWith` param.
})
  
```

#### Use it with Connect 4337:

```typescript
import {
    createComethPaymasterClient,
    createSafeSmartAccount,
    createSmartAccountClient,
} from "@cometh/connect-sdk-4337";
import { type Hex, type PublicClient, createPublicClient, http } from "viem";
import { arbitrumSepolia } from "viem/chains";


const apiKey = process.env.COMETH_API_KEY;
const bundlerUrl = process.env.4337_BUNDLER_URL;
const paymasterUrl = process.env.NEXT_PUBLIC_4337_PAYMASTER_URL;

const publicClient = createPublicClient({
    chain: arbitrumSepolia,
    transport: http(),
    cacheTime: 60_000,
    batch: {
        multicall: { wait: 50 },
    },
}) as PublicClient;

const smartAccount = await createSafeSmartAccount({
    apiKey,
    signer: turnkeySigner,
    chain: arbitrumSepolia,
    publicClient,
    smartAccountAddress //if smart account already exists
 });
 
const walletAddress = smartAccount.address

const paymasterClient = await createComethPaymasterClient({
    transport: http(paymasterUrl),
    chain: arbitrumSepolia,
    publicClient,
});

const smartAccountClient = createSmartAccountClient({
    account: smartAccount,
    chain: arbitrumSepolia,
    bundlerTransport: http(bundlerUrl, {
        retryCount: 5,
        retryDelay: 1000,
        timeout: 20_000,
    }),
    paymaster: paymasterClient,
    userOperation: {
        estimateFeesPerGas: async () => {
            return await paymasterClient.getUserOperationGasPrice();
        },
    },
});
  
```