Skip to main content

How to use Web3Auth React Native SDK in Expo Workflow

pnpreact nativeexpoandroidiosevmWeb3Auth Team | December 16, 2022

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:

Web3Auth Core - Social Login Flow

  • 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.

    Plug n Play Project Creation on Web3Auth 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 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.

      Plug n Play Project - Whitelist

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

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.
App.js
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, we will be talking through the Web3Auth React Native SDK.

Installation

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

Expo Web Browser

When using our SDK with an 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

Expo Secure Store

We will require a SecureStore implementation to allow for session management without storing the private key on the device.

expo install expo-secure-store

Initialization

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

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 customize 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";

Importing SecureStore implementation

import * as SecureStore from "expo-secure-store";

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 Sapphire Devnet network. For production usage, you can use the Sapphire Mainnet network.

const web3auth = new Web3Auth(WebBrowser, SecureStore, {
clientId,
network: OPENLOGIN_NETWORK.SAPPHIRE_MAINNET, // SAPPHIRE_MAINNET or SAPPHIRE_DEVNET
});
SDK Reference

Authentication

Logging in

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

JWT

If you are using custom authentication through Auth0 or Custom JWT, you have to use the JWT login provider.

Additionally, in extraLoginOptions you have to provide the details required by that specific method as mentioned here.

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.
});
SDK Reference

If you wish you add Multi Factor Authentication, use dApp Share

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();
SDK Reference

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.

connect any blockchain

Please go through the Connect Blockchain Documentation, which contains all the details of the EVM based blockchain you have selected here.

Troubleshooting React Native issues

Some commonly faced issues and the ways to fix them are addressed in this troubleshooting guide.

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 Support Portal