How to create private key authentication

Authorize transactions with a private key.

Overview

FunWallet is the core class of the FunKit SDK. It enables you to execute any transaction on an EVM chain and provides a straightforward method for implementing robust authentication schemes. In this guide, I will show you how to create a FunWallet object using a private key.

Import required objects

We have to import three objects in order to create a FunWallet.

FunWallet to create the object.
configureEnvironment to set up the environment for a FunWallet.
Auth for authenticating into a FunWallet.

import { FunWallet, configureEnvironment, Auth } from "@funkit/core";

Configuring the FunWallet environment

To begin, we need to set up the environment for your FunWallet. This is usually boilerplate code, but I will show you the process so that you can make adjustments in the future.

Let me explain the environment variables that we will need to input.

chain - Each FunWallet exists on an EVM-compatible blockchain, and for this guide, we will be using the Goerli testnet.
gasSponsor - All wallets have to pay gas to execute transactions on a blockchain and FunWallets are no exception to that. But FunWallets also have the option of a gas sponsor that can cover the gas cost. For this guide, we will use a gasless sponsor that is specified by sponsorAddress.
apiKey - We have provided a rate limited apiKey used strictly for demoing purposes. Please visit our dashboard to receive your own production apiKey.

It is important to note that the use of a gasSponsor is tied to your apiKey.

await configureEnvironment({
  chain: "goerli",
  gasSponsor: {
    sponsorAddress: "0xCB5D0b4569A39C217c243a436AC3feEe5dFeb9Ad",
  },
  apiKey: "ZrhepzWGxm74D0sqstuhT6dGrJxhoy8SZIToX6I3",
});

Creating Auth with a private key

Now that we’ve set up the environment, we need a way to sign transactions. All authentication in FunKit is handled with the Auth object.

We’ll use a private key as the authentication method and I’ll provide us with one. A private key for Ethereum consists of a 256-bit integer, and there are multiple methods for generating one.

const privateKey = generatePrivateKey();
const auth = new Auth({ privateKey });

Initializing FunWallet with Auth

With the Auth instance that we created in the step before, we are now able to initialize your FunWallet. Here are the FunWallet constructor parameters

users - This is an User[] that holds all users that can access your FunWallet. Since we’re only using 1 private key, our User[] only has 1 instance.
uniqueId - This is a random seed that is generated from our Auth instance. The purpose of this seed is the generate the address of our FunWallet.

const privateKey = generatePrivateKey();
const auth = new Auth({ privateKey });

const funWallet = new FunWallet({
  users: [{ userId: auth.getAddress() }],
  uniqueId: auth.getWalletUniqueId(),
});

FunWallets are generated using a uniqueId. Each uniqueId can create a unique FunWallet, allowing one private key to control multiple addresses.

Creating FunWallet

The final step is call .create(). This will execute a transaction on the Goerli testnet (chain)to deploy your FunWallet .

funWallet.create(auth, userId);

Summary

Putting together all the pieces we have createWallet() that you can use to create your FunWallet.

,single-auth.jsimport { FunWallet, Auth, configureEnvironment, generatePrivateKey } from '@funkit/core'

const createWallet = async () => {
await configureEnvironment({
chain: "goerli",
gasSponsor: {
sponsorAddress: "0xCB5D0b4569A39C217c243a436AC3feEe5dFeb9Ad"
},
apiKey: "ZrhepzWGxm74D0sqstuhT6dGrJxhoy8SZIToX6I3"
})

const privateKey = generatePrivateKey()
const auth = new Auth({ privateKey })

const funWallet = new FunWallet({
users: [{ userId: await auth.getAddress() }],
uniqueId: await auth.getWalletUniqueId()
})

await funWallet.create(auth, await auth.getAddress())
}

createWallet()