# Use Dfns with ZeroDev (/sdk/v5_3_x/signers/dfns)

> For the complete documentation index, see [llms.txt](/llms.txt)



<VersionWarning version="5.3.x" />

[Dfns](https://www.dfns.co/) is an MPC/TSS Wallet-as-a-Service API/SDK provider. Dfns aims to optimize the balance of security and UX by deploying key shares into a decentralized network on the backend while enabling wallet access via biometric open standards on the frontend like Webauthn. Reach out [here](https://www.dfns.co/learn-more) to set up a sandbox environment to get started.

## Set up [#set-up]

To use Dfns with ZeroDev, first create an application that integrates with Dfns.

* Refer to the [Dfns documentation site](https://docs.dfns.co/d/) for instructions on setting up an application with the Dfns.

## Integration [#integration]

Integrating ZeroDev with Dfns is straightforward after setting up the project. Dfns provides an Externally Owned Account (EOA) wallet to use as a signer with Kernel.

### Set up Dfns [#set-up-dfns]

After following the Dfns documentation, you will have access to a `dfnsWallet` object as shown below:

```typescript
import { DfnsWallet } from "@dfns/lib-viem";
import { DfnsApiClient } from "@dfns/sdk";
import { AsymmetricKeySigner } from "@dfns/sdk-keysigner";

// See the Dfns example https://github.com/dfns/dfns-sdk-ts/tree/m/examples/libs/viem/alchemy-aa-gasless for details on populating the environment variables.
const DFNS_PRIVATE_KEY = null;
const DFNS_CRED_ID = null;
const DFNS_APP_ORIGIN = null;
const DFNS_APP_ID = null;
const DFNS_AUTH_TOKEN = null;
const DFNS_API_URL = null;
const AMOY_WALLET_ID = null;

const initDfnsWallet = (walletId: string) => {
  const signer = new AsymmetricKeySigner({
    privateKey: DFNS_PRIVATE_KEY!,
    credId: DFNS_CRED_ID!,
    appOrigin: DFNS_APP_ORIGIN!,
  });

  const dfnsClient = new DfnsApiClient({
    appId: DFNS_APP_ID!,
    authToken: DFNS_AUTH_TOKEN!,
    baseUrl: DFNS_API_URL!,
    signer,
  });

  return DfnsWallet.init({
    walletId,
    dfnsClient,
    maxRetries: 10,
  });
};
```

### Use with ZeroDev [#use-with-zerodev]

Use the WalletClient from Dfns to create a smart account signer, which can be passed to a validator. For detailed guidance on using a validator, refer to our documentation on [creating accounts](/sdk/v5_3_x/core-api/create-account#api).

```typescript
import { signerToEcdsaValidator } from "@zerodev/ecdsa-validator"
import { KERNEL_V3_1 } from "@zerodev/sdk/constants"
import { walletClientToSmartAccountSigner, ENTRYPOINT_ADDRESS_V07 } from 'permissionless';
import { toAccount } from 'viem/accounts';
import { createWalletClient, createPublicClient } from 'viem';
import { polygonAmoy } from 'viem/chains';

// Convert the dfns wallet to a SmartAccountSigner
const amoyWallet = await initDfnsWallet(AMOY_WALLET_ID!);
const account = toAccount(amoyWallet)
const walletClient = createWalletClient({
    account,
    transport: http('https://rpc-amoy.polygon.technology'),
})
const smartAccountSigner = walletClientToSmartAccountSigner(walletClient);

const publicClient = createPublicClient({
  // Use your own RPC provider (e.g. Infura/Alchemy).
  transport: http('https://rpc-amoy.polygon.technology'),
  chain: polygonAmoy,
})

// Pass your `smartAccountSigner` to the validator
const ecdsaValidator = await signerToEcdsaValidator(publicClient, {
  signer: smartAccountSigner,
  entryPoint: ENTRYPOINT_ADDRESS_V07,
  kernelVersion: KERNEL_V3_1
})

// You can now use this ECDSA Validator to create a Kernel account
```