Integrate Firebase with Web3Auth Android SFA SDK

In this guide, we'll talk about how we can use Web3Auth Single Factor Auth with Firebase in your Android application.

As an overview, the guide is quite simple, with functionality to log in, display user details, and perform blockchain interactions. The signing of the blockchain transactions is done through the Web3Auth embedded wallet. You can check out the infrastructure docs, "Web3Auth Wallet Management Infrastructure" for a high-level overview of the Web3Auth architecture and implementation. For those who want to skip straight to the code, you can find it on GitHub.

How to set up Web3Auth Dashboard​

If you haven't already, sign up on the Web3Auth platform. It is free and gives you access to the Web3Auth's base plan. After the basic setup, explore other features and functionalities offered by the Web3Auth Dashboard. It includes custom verifiers, whitelabeling, analytics, and more. Head to Web3Auth's documentation page for detailed instructions on setting up the Web3Auth Dashboard.

How to set up Firebase for Android​

If you haven't already setup the Firebase for your Android app, please setup the Firebase, as it's the prerequisites for the guide. Head to the Firebase's documentation for the details instructions.

How to set up Custom verifier​

Once, you have set up the Web3Auth Dashboard, created a new project, and set up Firebase, it's time to create a Custom Verifier for your Firebase application. We already have detail instructions on how to create a Custom Verifier for Firebase, please head to our documentation.

Integrating Web3Auth SFA in Android​

Once, you have set up the Custom Verifier, it's time to integrate Web3Auth in your Android application. For the implementation, we'll use the "single-factor-auth-android". This SDK facilitates integration with Web3Auth. This way you can easily manage embedded wallet in your Android application.

Installation​

In your project-level build.gradle or settings.gradle file, add JitPack repository:

dependencyResolutionManagement {
    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        google()
        mavenCentral()
        maven { url "https://jitpack.io" } // <-- Add this line
    }
}

Then, in your app-level build.gradle dependencies section, add the following:

dependencies {
    // ...
    implementation 'com.github.web3auth:single-factor-auth-android:2.1.0'
}

For the prerequisites, and other mandatory configuration of the SDK, please head to our installation documentation.

Initialization​

After successfully installing the package, the next step is to instantiate SingleFactorAuth in your Android app. This sets up the necessary configurations using Web3Auth network and prepares the SDK. Learn more about SingleFactorAuth Initialization.

import android.content.Context
import com.web3auth.singlefactorauth.SingleFactorAuth
import com.web3auth.singlefactorauth.types.Web3AuthOptions
import org.torusresearch.fetchnodedetails.types.Web3AuthNetwork

// You can get the client id for your Web3Auth project from Web3Auth dashboard.
val web3AuthOptions = Web3AuthOptions(
    "YOUR_WEB3AUTH_CLIENT_ID",
    Web3AuthNetwork.SAPPHIRE_MAINNET
)

val context: Context = "YOUR_APPLICATION_CONTEXT"

val singleFactorAuth = SingleFactorAuth(web3AuthOptions, context)

Once you have successfully instantiated SingleFactorAuth, you can use the initialize method to initialize the SDK with existing valid session.

import android.content.Context

val context: Context = "YOUR_APPLICATION_CONTEXT"
val sessionDataCF = singleFactorAuth.initialize(context)

sessionDataCF.whenComplete {sessionData, error ->
    if(error != null) {
        // Something went wrong
        // Initiate the login flow again
    } else {
        // You can use the SessionData to check if the user is
        //logged in or not
    }
}

Authentication​

If the user is not authenticated, you should utilize the connect method. For the guide, we will add Email Password login using Firebase. The connect method is pretty straightforward in SingleFactorAuth and takes LoginParams as input. After successfully logging in, the method will return the SessionData.

Learn more about SingleFactorAuth LoginParams. To more about Firebase login methods, please checkout the Firebase documentation.

private var auth: FirebaseAuthauth = Firebase.auth

// Take the input for email and password from user
auth.signInWithEmailAndPassword("android@firebase.com", "Android@Web3Auth")
    .addOnCompleteListener(this) {
        task ->
        if (task.isSuccessful) {
            // Sign in success, update UI with the signed-in user's information
            Log.d(TAG, "signInWithEmail:success")
            val user = auth.currentUser

            // Try to get a fresh idToken
            user!!.getIdToken(true).addOnSuccessListener {
                result ->
                val idToken = result.token

                Log.d(TAG, "GetTokenResult result = $idToken")

                if (idToken != null) {
                   val sub = user!!.id

                   val loginParams = LoginParams(
                        // Replace with your custom verifier name
                        "web3auth-firebase-examples",
                        sub,
                        idToken
                    )

                    try {
                        // Save the SessionData for future use to interact with Blockchain.
                       sessionData = singleFactorAuth.connect(
                            loginParams,
                            this.applicationContext,
                            86400
                        ).get()

                    } catch (e: ExecutionException) {
                        e.printStackTrace()
                    } catch (e: InterruptedException) {
                        e.printStackTrace()
                    }

                    publicAddress =sessionData?.publicAddress.toString()

                    println("""Private Key: ${sfaKey?.privateKey?.toString(16)}""".trimIndent())
                    println("""Public Address: $publicAddress""".trimIndent())

                    // Additional code
                };
            }
        } else {
            // Upon failur, display a message to the user.
            Log.w(TAG, "signInWithEmail:failure", task.exception)
            Toast.makeText(
                baseContext, "Authentication failed.",
                Toast.LENGTH_SHORT
            ).show()
        }
    }

Set up Blockchain Providers​

Once we have successfully authenticated the user, the next step would be to fetch the user details, retrieve wallet address and prepare blockchain providers for interactions. For this guide, we are supporting only Ethereum ecosystem, but the general idea can be used for any blockchain ecosystem.

For interacting with ethereum chains, we'll use the web3j SDK. For installation, in your app-level build.gradle's dependencies section, add the web3j dependency.

dependencies {
  // ...
  implementation 'org.web3j:core:4.8.7-android'
}

After successfully installing SDK, it's time to create Credentials instance to retrive user's EOA address, and interact with blockchain. To retrive the user's private key, we'll use the SFAkey instance.

val credentials: Credentials = Credentials.create(sfaKey!.privateKey!.toString(16))

// User's EOA address
Log.d(TAG, credentials.address)

To retrive user's balance, and interacting with Blockcahin, you can follow our detailed guide on how to interact with EVM chain guides. Since, you already have created Credentials instance, and retrived the user's EOA address, you can skip that part. To interact with Solana blockchain, you can checkout our Solana blockchain guide.

Conclusion​

Voila, you have learned how to use Web3Auth SFA SDK with Android application.

If you are interested in learning more about SFA SDK, please checkout our documentation for Android SFA SDK. You can find the code used for the guide on our examples repo.