Using Web3Auth React Native SDK in Expo Workflow

This guide will cover the basics of how to use the Web3Auth React Native SDK in your React Native application.

Live Demo: [Coming Soon]

Repository: https://github.com/Web3Auth/web3auth-pnp-examples/tree/main/react-native/rn-expo-example

Quick Start​

npx degit Web3Auth/web3auth-pnp-examples/react-native/rn-expo-example w3a-rn-expo-demo && cd w3a-rn-expo-demo && npm install

# For Android
npm run android
# For iOS
npm run ios

How it works?​

When integrating Web3Auth React Native SDK with Social Login the flow looks something like this:

• When a user logs in with Google, Google sends a JWT id_token to the app. This JWT token is sent to the Web3Auth SDK's login function.

• Finally, on successful validation of the JWT token, Web3Auth SDK will generate a private key for the user, in a self custodial way, resulting in easy onboarding for your user to the application.

Prerequisites​

• For Web Apps: A basic knowledge of JavaScript is required to use Web3Auth SDK.

• For Mobile Apps: For the Web3Auth Mobile SDKs, you have a choice between iOS, Android, React Native & Flutter. Please refer to the Web3Auth SDK Reference for more information.

• Create a Web3Auth account on the Web3Auth Dashboard

• Expo SDK 45 and above (for Expo Managed Workflow)

Setup​

Setup your Web3Auth Dashboard​

• Create a Project from the Project Section of the Web3Auth Developer Dashboard.

  

  • Enter your desired Project name.

  • Select the Product you want to use. For this guide, we'll be using the Plug n Play product.

  • Select the Platform type you want to use. For this guide, we'll be using the Web Application as the platform.

  • Select the Web3Auth Network as Sapphire Devnet. We recommend creating a project in the sapphire_devnet or tesnet network during development. While moving to a production environment, make sure to convert your project to sapphire_mainnet or any of the legacy mainnet network mainnet, aqua, or cyan network. Otherwise, you'll end up losing users and keys.

  • Select the blockchain(s) you'll be building this project on. For interoperability with Torus Wallets, you have the option of allowing the user's private key to be used in other applications using Torus Wallets (EVM, Solana, XRPL & Casper).

  • Finally, once you create the project, you have the option to whitelist your URLs for the project. Please whitelist the domains where your project will be hosted.

    

• Add {YOUR_APP_SCHEME}://auth in the Whitelist URL field of the Web3Auth Dashboard.

Configure Deep Link​

• Adding URL scheme to app.json

To allow the Expo based SDK to work with exported Expo Android apps, you need to add the designated scheme into app.json

{
  "expo": {
    "scheme": "web3authexpoexample" // replace with your own scheme
  }
}

• For constructing your redirectUrl, you'll need to use the expo-linking, which will help you generate a redirectUrl for your app. Make sure you register that URL in the Web3Auth Developer Dashboard.

import Constants, { AppOwnership } from "expo-constants";
import * as Linking from "expo-linking";

const resolvedRedirectUrl =
  Constants.appOwnership == AppOwnership.Expo || Constants.appOwnership == AppOwnership.Guest
    ? Linking.createURL("web3auth", {})
    : Linking.createURL("web3auth", { scheme: scheme });

Using the Web3Auth SDK​

To use the Web3Auth SDK, you need to add the dependency of the respective platform SDK of Web3Auth to your project. To know more about the available SDKs, please have a look at this documentation page.

For this guide here, we will be talking through the Web3Auth React Native SDK.

Installation​

@web3auth/react-native-sdk​

npm install --save @web3auth/react-native-sdk

yarn add @web3auth/react-native-sdk

pnpm add @web3auth/react-native-sdk

Expo Web Browser​

When using our SDK with a Expo-based React Native app (aka managed workflow, you have to install the expo-web-browser package as a WebBrowser implementation.)

expo install expo-web-browser

Initialization​

After Installation, the next step to use Web3Auth is to Initialize the SDK. The Initialization is a two step process,

• Importing Required Packages
• Instantiating Web3Auth

Please note that these are the most critical steps where you need to pass on different parameters according to the preference of your project. Additionally, Whitelabeling and Custom Authentication have to be configured within this step, if you wish to customise your Web3Auth Instance.

Importing Web3Auth​

You may also import additional types from the SDK to help in the development process.

import Web3Auth, { LOGIN_PROVIDER, OPENLOGIN_NETWORK } from "@web3auth/react-native-sdk";

Importing a WebBrowser implementation​

import * as WebBrowser from "expo-web-browser";

Instantiating Web3Auth​

It's time to create an instance of Web3Auth in the project.

We need clientId and target Web3Auth network to initialize the web3auth object.

• You can get your clientId from registering (above) on the Developer Dashboard.

• network signifies the network on which the deployed Web3Auth nodes are running. For testing purposes, we have a TESTNET network. For production usage, you can use the CYAN, MAINNET, & AQUA networks.

  danger

  Please don't use the TESTNET network for production usage. You may end up losing user keys.

const web3auth = new Web3Auth(WebBrowser, {
  clientId,
  network: OPENLOGIN_NETWORK.CYAN, // MAINNET, AQUA,  CYAN or TESTNET
});

Authentication​

Logging in​

Once initialized, you can use the login function of web3auth to navigate user to the login process. For each login method, you have to select the loginProvider such as google, facebook, twitch, jwt, email_passwordless etc.

Once a user logs in, the Web3Auth SDK returns their reconstructed private key. For EVM Blockchains, the secp256k1 private key is used to sign transactions. We also return an ed25519 compatible private key for other blockchains.

const web3authResponse = await web3auth.login({
  redirectUrl: resolvedRedirectUrl,
  mfaLevel: "default", // Pass on the mfa level of your choice: default, optional, mandatory, none
  loginProvider: "google", // Pass on the login provider of your choice: google, facebook, discord, twitch, twitter, github, linkedin, apple, etc.
});

If you wish you add Multi Factor Authentication, use dApp Share or select Curve for your React Native application, read the linked documentation.

• Multi Factor Authentication
• Using dApp Share
• Selecting Curve

Sample loginResponse​

{
  "aggregateVerifier": "tkey-google",
  "email": "john@gmail.com",
  "name": "John Dash",
  "profileImage": "https://lh3.googleusercontent.com/a/Ajjjsdsmdjmnm...",
  "typeOfLogin": "google",
  "verifier": "torus",
  "verifierId": "john@gmail.com",
  "dappShare": "<24 words seed phrase>", // will be sent only incase of custom verifiers
  "idToken": "<jwtToken issued by Web3Auth>",
  "oAuthIdToken": "<jwtToken issued by OAuth Provider>", // will be sent only incase of custom verifiers
  "oAuthAccessToken": "<accessToken issued by OAuth Provider>" // will be sent only incase of custom verifiers
}

Get the User Profile​

// Assuming the user is logged in, get the user profile from the web3AuthResponse
var userInfo = web3authResponse.userInfo;

Using the web3Auth.login() function, you can get the details of the logged in user. Please note that these details are not stored anywhere in Web3Auth network.

Sample userInfo​

{
  "aggregateVerifier": "tkey-google",
  "email": "john@gmail.com",
  "name": "John Dash",
  "profileImage": "https://lh3.googleusercontent.com/a/Ajjjsdsmdjmnm...",
  "typeOfLogin": "google",
  "verifier": "torus",
  "verifierId": "john@gmail.com",
  "dappShare": "<24 words seed phrase>", // will be sent only incase of custom verifiers
  "idToken": "<jwtToken issued by Web3Auth>",
  "oAuthIdToken": "<jwtToken issued by OAuth Provider>", // will be sent only incase of custom verifiers
  "oAuthAccessToken": "<accessToken issued by OAuth Provider>" // will be sent only incase of custom verifiers
}

Logout​

Use the logout function of web3auth to log the user out. This function doesn't work in iOS, so you need to navigate the user back manually.

web3auth.logout();

Interacting with the Blockchain​

Once a user logs in, the Web3Auth SDK returns their reconstructed private key. For EVM Blockchains, the secp256k1 private key is used to sign transactions. We also return an ed25519 compatible private key for other blockchains. Similar to how we're using this private key in the ethers.js library in this example, you can connect to any other blockchain of your choice.

Example code​

The code for the application we developed in this guide can be found in the Web3Auth React Native Example. Check it out and try running it locally yourself!

Questions?​

Ask us on Web3Auth's Community Portal