> ## Documentation Index
> Fetch the complete documentation index at: https://docs.turnkey.com/llms.txt
> Use this file to discover all available pages before exploring further.

# WalletStamper

## Introduction

The [`@turnkey/wallet-stamper`](https://www.npmjs.com/package/@turnkey/wallet-stamper) package provides a flexible mechanism for using your Solana or EVM wallet to stamp and approve activity requests for Turnkey's API. This stamping process leverages your wallet's signature key to authenticate requests securely.

## Installing

To get started, install the [`@turnkey/wallet-stamper`](https://www.npmjs.com/package/@turnkey/wallet-stamper) client.

<CodeGroup>
  ```bash npm theme={"system"}
  npm i @turnkey/wallet-stamper
  ```

  ```bash pnpm theme={"system"}
  pnpm i @turnkey/wallet-stamper
  ```

  ```bash yarn theme={"system"}
  yarn add @turnkey/wallet-stamper
  ```
</CodeGroup>

## Initializing

The `WalletStamper` class implements the `TStamper` interface used by the [TurnkeyClient](/sdks/advanced/turnkey-client) in the [`@turnkey/http`](https://www.npmjs.com/package/@turnkey/http) package. It encapsulates the logic necessary to sign activity requests using your wallet and generate the appropriate HTTP headers for authentication.

### `constructor(wallet: WalletInterface): TStamper`

#### Parameters

<ParamField body="wallet" type="WalletInterface" required>
  An object representing your wallet, either a Solana or EVM wallet.
</ParamField>

<ParamField body="type" type="string" required>
  The type of wallet, either `solana` or `evm`.
</ParamField>

<ParamField body="signMessage" type="function" required>
  A function that signs a message using your wallet's private key.
</ParamField>

<ParamField body="recoverPublicKey" type="function" required>
  A function that recovers the public key from the signed message (required for EVM wallets).
</ParamField>

#### Types

##### `SolanaWalletInterface`

```js theme={"system"}
export interface SolanaWalletInterface extends BaseWalletInterface {
  recoverPublicKey: () => string;
  type: "solana";
}
```

##### `EvmWalletInterface`

```js theme={"system"}
export interface EvmWalletInterface extends BaseWalletInterface {
  recoverPublicKey: (message: string, signature: string) => Promise<string>;
  type: "evm";
}
```

##### `WalletInterface`

```js theme={"system"}
export type WalletInterface = SolanaWalletInterface | EvmWalletInterface;
```

## Methods

### `stamp: (input: string) => Promise<TStamp>`

Signs the payload using the wallet's private key and returns the stamp to be used in the HTTP headers for authenticating requests to Turnkey's API.

#### Parameters

<ParamField body="payload" type="string" required>
  The payload that to be stamped. This is the stringified JSON request body that you want to send to Turnkey's API.
</ParamField>

#### Types

##### `TStamp`

```js theme={"system"}
type TStamp = {
  stampHeaderName: string;
  stampHeaderValue: string;
};
```

##### `TStamper`

```js theme={"system"}
interface TStamper {
  stamp: (input: string) => Promise<TStamp>;
}
```

## Example

The example below shows how to initialize and use the `WalletStamper` with the `TurnkeyClient` to make a request to Turnkey's [`/public/v1/query/whoami`](/api-reference/sessions/who-am-i) endpoint:

```js theme={"system"}
// Import the dependencies for the Solana
import { Keypair } from "@solana/web3.js";
import { decodeUTF8 } from "tweetnacl-util";
import nacl from "tweetnacl";

import { TurnkeyClient } from "@turnkey/http";
import { WalletStamper, SolanaWalletInterface } from "@turnkey/wallet-stamper";

class SolanaWallet implements SolanaWalletInterface {
  keypair = Keypair.fromSecretKey(SOLANA_PRIVATE_KEY);
  type = "solana" as const;

  async signMessage(message: string): Promise<string> {
    const messageBytes = decodeUTF8(message);
    const signature = nacl.sign.detached(messageBytes, this.keypair.secretKey);
    return Buffer.from(signature).toString("hex");
  }

  recoverPublicKey(): string {
    // Convert the base24 encoded Solana wallet public key (the one displayed in the wallet)
    // into the ed25519 decoded public key
    const ed25519PublicKey = Buffer.from(
      this.keypair.publicKey.toBuffer(),
    ).toString("hex");
    return ed25519PublicKey;
  }
}

// Instantiate the WalletStamper with the SolanaWallet
const walletStamper = new WalletStamper(new SolanaWallet());

// Instantiate the TurnkeyClient with the WalletStamper
const client = new TurnkeyClient({ baseUrl: BASE_URL }, walletStamper);

// You're now ready to make requests to Turnkey's API 🎉
```

## Conclusion

The `WalletStamper` class provides a seamless integration with Turnkey's API, enabling you to leverage your existing wallet for secure, authenticated requests. By following this guide, you can quickly set up and start using `WalletStamper` in your projects.