Biometric Authentication | Android Studio | Kotlin

How to do Biometric Authentication?

In this tutorial, we will learn how to use Biometric Authentication e.g. Fingerprint Authentication/Login. There may be some features in your app that needs user authentication. So here is the simplest example of using Biometric Authentication.

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Video:

Step 1: Create a new project OR Open your existing project

Step 2: Code

build.gradle

Add the biometric library to app-level build.gradle file

dependencies {
    implementation 'androidx.biometric:biometric:1.0.1'
}

AndroidManifest.xml

Add the USE_BIOMETRIC dependency to the AndroidManifest.xml file

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.wongngaur.blogspot.biometricauthentication">

    <!--Add permission-->
    <uses-permission android:name="android.permission.USE_BIOMETRIC"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="50dp"
    tools:context=".MainActivity">

    <ImageView
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:layout_centerHorizontal="true"
        android:src="@drawable/lock_vector"/>

    <TextView
        android:id="@+id/authStatusTv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:textColor="#000"
        android:textSize="20sp"
        android:text="Click button to start authentication" />

    <Button
        android:id="@+id/authBtn"
        android:layout_below="@id/authStatusTv"
        android:layout_centerHorizontal="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dp"
        android:text="Authenticate"
        style="@style/Widget.AppCompat.Button.Colored"
        android:drawableStart="@drawable/ic_fingerprint_white"
        android:drawablePadding="10dp"/>

</RelativeLayout>

MainActivity.kt

package com.wongngaur.blogspot.biometricauthentication

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import androidx.biometric.BiometricManager
import androidx.biometric.BiometricPrompt
import androidx.core.content.ContextCompat
import kotlinx.android.synthetic.main.activity_main.*
import java.util.concurrent.Executor

class MainActivity : AppCompatActivity() {

    private lateinit var executor: Executor
    private lateinit var biometricPrompt: BiometricPrompt
    private lateinit var promptInfo: BiometricPrompt.PromptInfo

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        //init biometric
        executor = ContextCompat.getMainExecutor(this)

        biometricPrompt = BiometricPrompt(this@MainActivity, executor, object : BiometricPrompt.AuthenticationCallback(){
            override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
                super.onAuthenticationError(errorCode, errString)
                //auth error, stop tasks that requires auth
                authStatusTv.text = "Authentication Error: $errString"
                Toast.makeText(this@MainActivity, "Authentication Error: $errString", Toast.LENGTH_SHORT).show()
            }

            override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
                super.onAuthenticationSucceeded(result)
                //auth succeed, do tasks that requires auth
                authStatusTv.text = "Auth succeed...!"
                Toast.makeText(this@MainActivity, "Auth succeed...!", Toast.LENGTH_SHORT).show()

            }

            override fun onAuthenticationFailed() {
                super.onAuthenticationFailed()
                //auth failed, stop tasks that requires auth
                authStatusTv.text = "Auth failed...!"
                Toast.makeText(this@MainActivity, "Auth failed...!", Toast.LENGTH_SHORT).show()
            }
        })

        //set properties like title and description on auth dialog
        promptInfo = BiometricPrompt.PromptInfo.Builder()
                .setTitle("Biometric Authentication")
                .setSubtitle("Login using fingerprint authentication")
                .setNegativeButtonText("Use App Password instead")
                .build()

        //handle click, start authtenitcation dialog
        authBtn.setOnClickListener {
            //show auth dialog
            biometricPrompt.authenticate(promptInfo)
        }
    }
}