Biometric Authentication Fingerprint Example

See the blog post of this project here

Project Presentation

1. First, let's add the Biometric library to our project.

   dependencies {
     implementation("androidx.biometric:biometric:1.2.0-alpha03")
   }

   
   
2. After adding our library, let's do the necessary coding for situations such as whether the device has biometric authentication or not.

   val biometricManager = BiometricManager.from(this)
   when (biometricManager.canAuthenticate(BIOMETRIC_STRONG or DEVICE_CREDENTIAL)) {
   BiometricManager.BIOMETRIC_SUCCESS ->
       Toast.makeText(this,"App can authenticate using biometrics.",Toast.LENGTH_SHORT).show()
   BiometricManager.BIOMETRIC_ERROR_NO_HARDWARE ->
       Toast.makeText(this,"No biometric features available on this device.",Toast.LENGTH_SHORT).show()
   BiometricManager.BIOMETRIC_ERROR_HW_UNAVAILABLE ->
       Toast.makeText(this,"Biometric features are currently unavailable.",Toast.LENGTH_SHORT).show()
   BiometricManager.BIOMETRIC_ERROR_NONE_ENROLLED ->
       Toast.makeText(this,"The device does not have any biometric credentials",Toast.LENGTH_SHORT).show()
   BiometricManager.BIOMETRIC_ERROR_SECURITY_UPDATE_REQUIRED ->
       Toast.makeText(this,"A security vulnerability has been discovered and the sensor is unavailable until a security update has addressed this issue.",Toast.LENGTH_SHORT).show()
   BiometricManager.BIOMETRIC_ERROR_UNSUPPORTED ->
       Toast.makeText(this,"A given authenticator combination is not supported by the device.",Toast.LENGTH_SHORT).show()
   BiometricManager.BIOMETRIC_STATUS_UNKNOWN ->
       Toast.makeText(this,"Unable to determine whether the user can authenticate.",Toast.LENGTH_SHORT).show()
   }

3. Now let's show the user the authentication dialog. First of all, let's create the following variables in the class.

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

   
   

4. Then let's define these values in order.

   executor = ContextCompat.getMainExecutor(this)
   biometricPrompt = BiometricPrompt(this, executor,
   object : BiometricPrompt.AuthenticationCallback() {
       override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
           super.onAuthenticationError(errorCode, errString)
           Toast.makteText(this,errString.toString(),Toast.LENGTH_SHORT).show()
       }
   
       override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
           super.onAuthenticationSucceeded(result)
           Toast.makteText(this,"Authentication Success",Toast.LENGTH_SHORT).show()
           startActivity(Intent(this@MainActivity,SecondActivity::class.java))
       }
   
       override fun onAuthenticationFailed() {
           super.onAuthenticationFailed()
           Toast.makteText(this,"Authentication Failed",Toast.LENGTH_SHORT).show()
       }
   })

   
   

5. Now, let's define the promptInfo variable.

   promptInfo = BiometricPrompt.PromptInfo.Builder()
   .setTitle("Biometric login for my app")
   .setSubtitle("Log in using your biometric credential")
   .setNegativeButtonText("Cancel")
   .build()

   
   

6. Finally, we use the authenticate function to show our dialog when the button is clicked and give the biometricPrompt the promptInfo.

   binding.button.setOnClickListener {
       biometricPrompt.authenticate(promptInfo)
   }

   
   

And Result