isaidamier

class MainActivity : AppCompatActivity() {
  ...
   private lateinit var biometricPrompt: BiometricPrompt
   private lateinit var promptInfo: BiometricPrompt.PromptInfo
   ...

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

isaidamier

class MainActivity : AppCompatActivity() {

   private lateinit var biometricPrompt: BiometricPrompt
   private lateinit var promptInfo: BiometricPrompt.PromptInfo
   private var readyToEncrypt: Boolean = false
   ...
   override fun onCreate(savedInstanceState: Bundle?) {
       super.onCreate(savedInstanceState)
       setContentView(R.layout.activity_main)
       ...

isaidamier

class MainActivity : AppCompatActivity() {

    private lateinit var textInputView: AppCompatEditText
    private lateinit var textOutputView: AppCompatTextView
    private lateinit var biometricPrompt: BiometricPrompt
    private lateinit var promptInfo: BiometricPrompt.PromptInfo
    private var readyToEncrypt: Boolean = false
    private lateinit var cryptographyManager: CryptographyManager
    private lateinit var secretKeyName: String
    private lateinit var ciphertext:ByteArray

isaidamier

override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
    super.onAuthenticationError(errorCode, errString)
    Log.d(TAG, "$errorCode :: $errString")
    if (errorCode == BiometricPrompt.ERROR_USER_CANCELED) {
        handleUserCancelation() // this is your custom function
    }
}

isaidamier

if (ciphertextWrapper != null) {
   // user has already enabled biometrics
} else {
   // biometrics has not been enabled
}

isaidamier

binding.useBiometrics.setOnClickListener {
   showBiometricPromptForEncryption()
}
....

private fun showBiometricPromptForEncryption() {
   val canAuthenticate = BiometricManager.from(applicationContext).canAuthenticate()
   if (canAuthenticate == BiometricManager.BIOMETRIC_SUCCESS) {
       val secretKeyName = SECRET_KEY_NAME
       cryptographyManager = CryptographyManager()

isaidamier

dependencies {
    implementation 'com.google.android.gms:play-services-nearby:18.0.0'
}