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Learn how to implement Web3Auth Android SDK

plug and playandroidkotlinevmWeb3Auth Team | August 12, 2022

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

Demo APK: Download

Repository: https://github.com/Web3Auth/web3auth-pnp-examples/tree/main/android/android-quick-start

Live Demo

Quick Start​

npx degit Web3Auth/web3auth-pnp-examples/android/android-quick-start w3a-android-demo
# Open in Android Studio

How it works?​

When integrating Web3Auth Android 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

  • Android API version 21 or newer.

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 Android 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 Mainet, 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

Using the Web3Auth SDK​

To use the Web3Auth SDK, you'll 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 our SDK page.

For this guide, we will be using the Web3Auth Android SDK.

To use the Web3Auth SDK, you'll 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 our SDK page.

For this guide, we will be using the Web3Auth Android SDK.

Add Web3Auth to Gradle​

In your project-level 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:web3auth-android-sdk:8.0.3'
}

Permissions​

Open your app's AndroidManifest.xml file and add the following permission. Please make sure the <uses-permission> element should be a direct child of the <manifest> root element.

<uses-permission android:name="android.permission.INTERNET" />

Configuration​

Configure a Plug n Play project​

  • Go to Web3Auth Developer Dashboard, and create or open an existing Web3Auth project.
  • Whitelist {SCHEME}://{YOUR_APP_PACKAGE_NAME} in the developer dashboard. This step is mandatory for the redirect to work.

Configure AndroidManifest File​

Make sure your Main activity launchMode is set to singleTop in your AndroidManifest.xml

<activity
  android:launchMode="singleTop"
  android:name=".YourActivity">
  // ...
</activity>

From version 7.1.2, please make sure to set android:allowBackup to false, and add tools:replace="android:fullBackupContent" in your AndroidManifest.xml file.

<application
        android:allowBackup="false"
        tools:replace="android:fullBackupContent"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher">
</application>

Open your app's AndroidManifest.xml file and add the following deep link intent filter to your Main activity

<intent-filter>
  <action android:name="android.intent.action.VIEW" />

  <category android:name="android.intent.category.DEFAULT" />
  <category android:name="android.intent.category.BROWSABLE" />

  <data android:scheme="{scheme}" android:host="{YOUR_APP_PACKAGE_NAME}" android:path="/path" />
  <!-- Accept URIs: w3a://com.example.w3aflutter -->
</intent-filter>

Initialization​

Initialization is a two-step process:

  1. Creating a Web3Auth Instance
  2. Setting a Result URL

Please note that these are the most critical steps where you must pass on different parameters according to the preference of your project. Additionally, You must configure Whitelabeling and Custom Authentication within this step if you wish to customize your Web3Auth Instance.

Create Web3Auth Instance​

In your activity, create a Web3Auth instance with your Web3Auth project's configurations.

import com.web3auth.core.Web3Auth
import com.web3auth.core.types.Web3AuthOptions

var web3Auth = Web3Auth(
  Web3AuthOptions(
    context = this,
    clientId = "YOUR_WEB3AUTH_CLIENT_ID", // Pass over your Web3Auth Client ID from Developer Dashboard
    network = Network.MAINNET,
    redirectUrl = Uri.parse("{YOUR_APP_PACKAGE_NAME}://auth"),
  )
)

// Handle user signing in when app is in background
web3Auth.setResultUrl(intent?.data)

Read more about initializing the Android SDK here.

Set Result URL​

Whenever user initiates a login flow, a new intent of CustomTabs is launched. It’s necessary step to use setResultUrl in onNewIntent method to successful track the login process.

override fun onNewIntent(intent: Intent?) {
  super.onNewIntent(intent)

  // Handle user signing in when app is active
  web3Auth.setResultUrl(intent.data)
}

Authentication​

Logging in​

Once initialized, you can use the web3Auth.login(LoginParams("{selectedLoginProvider}")) function to authenticate the user when they click the login button.

private fun signIn() {
  val selectedLoginProvider = Provider.GOOGLE   // Can be GOOGLE, FACEBOOK, TWITCH etc.
  val loginCompletableFuture: CompletableFuture<Web3AuthResponse> = web3Auth.login(LoginParams(selectedLoginProvider))

  loginCompletableFuture.whenComplete { loginResponse, error ->
    if (error == null) {
      // render logged in UI
      println(loginResponse)
    } else {
      // render error UI
    }
  }
}

When connecting, the login function takes the LoginParams arguments for the login. See the LoginParams for more details.

Sample loginResponse​

{
  "privKey": "0ajjsdsd....",
  "userInfo": {
    "email": "w3a-heroes@web3auth.com",
    "name": "Web3Auth Heroes",
    "profileImage": "https://lh3.googleusercontent.com/a/Ajjjsdsmdjmnm...",
    "verifier": "torus",
    "verifierId": "w3a-heroes@web3auth.com",
    "typeOfLogin": "google",
    "aggregateVerifier": "w3a-google-sapphire",
    "dappShare": "", // 24 words of 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
    "isMfaEnabled": false // Returns whether the user has enabled MFA or not
  },
  "ed25519PrivKey": "666523652352635....",
  "coreKitKey": "0xajjsdsd....",
  "coreKitEd25519PrivKey": "666523652352635....",
  "sessionId": "0xajjsdsd...."
}

Get the User Profile​

// Assuming the user is logged in, get the user profile from the web3AuthResponse
val 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.

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

Logout​

Logging out your user is as simple as calling the logout method. This method will clear the session data and the user will be logged out from Web3Auth.

val logoutCompletableFuture = web3Auth.logout()

Interacting with the Blockchain​

Blockchain calls

Checkout the full codes to interact with the ETH Blockchain.

Get Account​

// checkout the Connect Blockchain > Ethereum > Android to get full code.
private fun getAddress(): String {
  println("Address:, ${credentials.address}")
  return credentials.address
}

// Setup UI and event handlers
val getBalanceButton = findViewById<Button>(R.id.getBalanceButton)
getBalanceButton.setOnClickListener { getAddress() }

Get Balance​

// checkout the Connect Blockchain > Ethereum > Android to get full code.
private fun getBalance(): BigInteger? {
  val publicAddress = credentials.address
  val ethBalance: EthGetBalance = web3.ethGetBalance(publicAddress, DefaultBlockParameterName.LATEST).sendAsync().get()
  println("Balance: ${ethBalance.balance}")
  return ethBalance.balance
}

// Setup UI and event handlers
val getBalanceButton = findViewById<Button>(R.id.getBalanceButton)
getBalanceButton.setOnClickListener { getBalance() }

Send Transaction​

// checkout the Connect Blockchain > Ethereum > Android to get full code.
private fun sendTransaction(amount: Double, recipientAddress: String): String? {
  val ethGetTransactionCount: EthGetTransactionCount = web3.ethGetTransactionCount(credentials.address, DefaultBlockParameterName.LATEST).sendAsync().get()
  val nonce: BigInteger = ethGetTransactionCount.transactionCount
  val value: BigInteger = Convert.toWei(amount.toString(), Convert.Unit.ETHER).toBigInteger()
  val gasLimit: BigInteger = BigInteger.valueOf(21000)
  val chainId: EthChainId = web3.ethChainId().sendAsync().get()

  // Raw Transaction
  val rawTransaction: RawTransaction = RawTransaction.createTransaction(
    chainId.chainId.toLong(),
    nonce,
    gasLimit,
    recipientAddress,
    value,
    "",
    BigInteger.valueOf(5000000000),
    BigInteger.valueOf(6000000000000)
  )

  val signedMessage: ByteArray = TransactionEncoder.signMessage(rawTransaction, credentials)
  val hexValue: String = Numeric.toHexString(signedMessage)
  val ethSendTransaction: EthSendTransaction = web3.ethSendRawTransaction(hexValue).sendAsync().get()
  return if(ethSendTransaction.error != null) {
    println("Tx Error: ${ethSendTransaction.error.message}")
    ethSendTransaction.error.message
  } else {
    println("Tx Hash: ${ethSendTransaction.transactionHash}")
    ethSendTransaction.transactionHash
  }
}

// Setup UI and event handlers
val sendTransactionButton = findViewById<Button>(R.id.sendTransactionButton)
sendTransactionButton.setOnClickListener { sendTransaction() }

Example code​

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

Also, checkout other examples:

Questions?​

Ask us on Web3Auth's Community Support Portal