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Authentication has been done for API below 30 #1

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f11d756
Authentication has been done for API below 30
Jul 2, 2025
7822524
The problem with the authentication prompt not appearing after switch…
Jul 21, 2025
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212 changes: 135 additions & 77 deletions app/src/main/java/com/example/biometricpropmpts/MainActivity.kt
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Original file line number Diff line number Diff line change
@@ -1,19 +1,20 @@
package com.example.biometricpropmpts

import android.app.KeyguardManager
import android.content.Context
import android.content.Intent
import android.os.Build
import android.os.Bundle
import android.provider.Settings
import android.util.Log
import android.view.WindowInsets
import android.widget.Toast
import com.example.biometricpropmpts.R
import androidx.activity.compose.rememberLauncherForActivityResult
import androidx.activity.compose.setContent
import androidx.activity.enableEdgeToEdge
import androidx.activity.result.ActivityResultLauncher
import androidx.activity.result.contract.ActivityResultContracts
import androidx.activity.viewModels
import androidx.annotation.RequiresApi
import androidx.biometric.BiometricManager
import androidx.biometric.BiometricManager.Authenticators.BIOMETRIC_STRONG
import androidx.biometric.BiometricManager.Authenticators.DEVICE_CREDENTIAL
Expand All @@ -22,40 +23,33 @@ import androidx.compose.foundation.background
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.PaddingValues
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.WindowInsetsSides
import androidx.compose.foundation.layout.defaultMinSize
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.wrapContentSize
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.Lock
import androidx.compose.material.icons.filled.Person
import androidx.compose.material3.Button
import androidx.compose.material3.ButtonDefaults
import androidx.compose.material3.Icon
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.OutlinedTextField
import androidx.compose.material3.OutlinedTextFieldDefaults
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.collectAsState
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Brush
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.vector.ImageVector
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.res.painterResource
import androidx.compose.ui.res.stringResource
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.text.input.PasswordVisualTransformation
Expand All @@ -67,20 +61,20 @@ import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.core.content.ContextCompat
import androidx.core.view.WindowCompat
import androidx.fragment.app.FragmentActivity
import com.example.biometricpropmpts.ui.theme.BiometricPropmptsTheme
import dagger.hilt.android.AndroidEntryPoint
import java.nio.charset.Charset
import javax.crypto.Cipher
import kotlin.reflect.KFunction1

@AndroidEntryPoint
class MainActivity : FragmentActivity() {
private lateinit var enrollLauncher: ActivityResultLauncher<Intent>
val TAG = "MyBiometricMain"
private lateinit var keyguardLauncher: ActivityResultLauncher<Intent>
private val TAG = "MyBiometricApp"
private var isEnrollClicked = false
private val viewModel: MainViewModel by viewModels()

@RequiresApi(Build.VERSION_CODES.R)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
enableEdgeToEdge()
Expand All @@ -91,39 +85,60 @@ class MainActivity : FragmentActivity() {
}
}

@RequiresApi(Build.VERSION_CODES.R)
override fun onRestart() {
super.onRestart()
viewModel.isBiometricEnrolled = isBiometricEnrolled()
}

private fun isBiometricEnrolled(): Boolean {
val biometricManager = BiometricManager.from(this)
val canAuthenticate = biometricManager.canAuthenticate(BIOMETRIC_STRONG)
return canAuthenticate == BiometricManager.BIOMETRIC_SUCCESS
}

@Composable
private fun EnrollBiometric() {
Scaffold( modifier = Modifier
.fillMaxSize()
.background(
brush = Brush.verticalGradient(
listOf(Color(0xFFA87FFB), Color(0xFF7B42F6))
)
), containerColor = Color.Transparent) { innerPadding ->
val viewModel: MainViewModel by viewModels()
Scaffold(
modifier = Modifier
.fillMaxSize()
.background(
brush = Brush.verticalGradient(listOf(Color(0xFFA87FFB), Color(0xFF7B42F6)))
),
containerColor = Color.Transparent
) { innerPadding ->

enrollLauncher = rememberLauncherForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
if (result.resultCode == RESULT_OK)
showToastMessage(this, R.string.biometric_enrolled)
else
showToastMessage(this, R.string.enrollment_canceled)
}

enrollLauncher =
rememberLauncherForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
keyguardLauncher = rememberLauncherForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
if (result.resultCode == RESULT_OK) {
Toast.makeText(this, "Biometric enrolled!", Toast.LENGTH_SHORT).show()
} else {
Toast.makeText(this, "Enrollment canceled.", Toast.LENGTH_SHORT).show()
}
if (isEnrollClicked) {
viewModel.encrypt(null)
isEnrollClicked = false
} else
viewModel.decrypt(null)

} else
showToastMessage(this, R.string.enrollment_canceled)
}

StylishLoginScreen(
modifier = Modifier.padding(innerPadding),
viewModel = viewModel,
onEnrollClick = {
checkBiometricAvailability(onSuccessful = {
viewModel.encrypt(::authenticate)
})
isEnrollClicked = true
checkBiometricAvailability(
onSuccessful = { viewModel.encrypt(::authenticate) }
)
},
onShowDecryptionClick = {
checkBiometricAvailability(onSuccessful = {
viewModel.decrypt(::authenticate)
})
checkBiometricAvailability(
onSuccessful = { viewModel.decrypt(::authenticate) }
)
}
)
}
Expand All @@ -140,96 +155,136 @@ class MainActivity : FragmentActivity() {
val biometricPrompt = BiometricPrompt(
this, executor,
object : BiometricPrompt.AuthenticationCallback() {

override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
super.onAuthenticationError(errorCode, errString)
Toast.makeText(
applicationContext,
"Authentication error: $errString", Toast.LENGTH_SHORT
).show()
showToastMessage(this@MainActivity, R.string.failed_authentication, errString.toString())
}

override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
super.onAuthenticationSucceeded(result)
onSucceedEncrypt?.let {
val encryptedPassword: ByteArray? =
result.cryptoObject?.cipher?.doFinal(
uiState.password.text.toByteArray(
Charset.defaultCharset()
)
)

Toast.makeText(
applicationContext,
"Authentication Succeed",
Toast.LENGTH_SHORT
)
.show()
result.cryptoObject?.cipher?.doFinal(uiState.password.text.toByteArray(Charset.defaultCharset()))

showToastMessage(this@MainActivity, R.string.succeed_authentication)

if (encryptedPassword != null)
onSucceedEncrypt(encryptedPassword)
}
onSucceedDecrypt?.let {
onSucceedDecrypt(result)
}

onSucceedDecrypt?.let { onSucceedDecrypt(result) }
}
})
}

)


val promptInfo = BiometricPrompt.PromptInfo.Builder()
.setTitle("Biometric login for my app")
.setSubtitle("Log in using your biometric credential")
.setAllowedAuthenticators(BIOMETRIC_STRONG or DEVICE_CREDENTIAL)
.build()

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R)
promptInfo.setAllowedAuthenticators(BIOMETRIC_STRONG or DEVICE_CREDENTIAL)

else
promptInfo.setNegativeButtonText("Cancel") // Mandatory for API < 30


biometricPrompt.authenticate(
promptInfo,
promptInfo.build(),
BiometricPrompt.CryptoObject(cipher)
)

}

@RequiresApi(Build.VERSION_CODES.R)
fun checkBiometricAvailability(onSuccessful: () -> Unit) {
private fun checkBiometricAvailability(onSuccessful: () -> Unit) {
val biometricManager = BiometricManager.from(this)
when (biometricManager.canAuthenticate(BIOMETRIC_STRONG or DEVICE_CREDENTIAL)) {
val result = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R)
biometricManager.canAuthenticate(BIOMETRIC_STRONG or DEVICE_CREDENTIAL)
else
biometricManager.canAuthenticate() // ⚠️ Deprecated, but correct for API < 30


when (result) {
BiometricManager.BIOMETRIC_SUCCESS -> {
Log.d(TAG, "App can authenticate using biometrics.")
onSuccessful()
Log.d("MY_APP_TAG", "App can authenticate using biometrics.")
}

BiometricManager.BIOMETRIC_ERROR_NO_HARDWARE ->
Log.e("MY_APP_TAG", "No biometric features available on this device.")
Log.e(TAG, "No biometric features available on this device.")

BiometricManager.BIOMETRIC_ERROR_HW_UNAVAILABLE ->
Log.e("MY_APP_TAG", "Biometric features are currently unavailable.")
Log.e(TAG, "Biometric features are currently unavailable.")

BiometricManager.BIOMETRIC_ERROR_UNSUPPORTED -> {
Log.e(TAG, "Biometric features are incompatible with the current Android version.")
showDeviceCredentialPrompt()
}

BiometricManager.BIOMETRIC_ERROR_NONE_ENROLLED -> {
// Prompts the user to create credentials that your app accepts.
val enrollIntent = Intent(Settings.ACTION_BIOMETRIC_ENROLL).apply {
putExtra(
Settings.EXTRA_BIOMETRIC_AUTHENTICATORS_ALLOWED,
BIOMETRIC_STRONG or DEVICE_CREDENTIAL
)
}
enrollLauncher.launch(enrollIntent)
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
val enrollIntent = Intent(Settings.ACTION_BIOMETRIC_ENROLL).apply {
putExtra(
Settings.EXTRA_BIOMETRIC_AUTHENTICATORS_ALLOWED,
BIOMETRIC_STRONG or DEVICE_CREDENTIAL
)
}

enrollLauncher.launch(enrollIntent)
} else
showDeviceCredentialPrompt()
}
}
}

@Suppress("DEPRECATION")
// KeyguardManager.createConfirmDeviceCredentialIntent(...) was deprecated in API 33 because Google now prefers BiometricPrompt, and
// there is no replacement for this on API 23–29
private fun showDeviceCredentialPrompt() {
val keyguardManager = getSystemService(Context.KEYGUARD_SERVICE) as KeyguardManager
val intent = keyguardManager.createConfirmDeviceCredentialIntent(
"Authentication Required",
"Use your screen lock to continue"
)

intent?.let {
keyguardLauncher.launch(it)
} ?: run {
// Device doesn't have secure lock screen
startActivity(Intent(Settings.ACTION_SECURITY_SETTINGS))
Log.e(TAG, "Device doesn't have secure lock screen")
}
}
}


@Composable
fun StylishLoginScreen(
modifier: Modifier = Modifier,
viewModel: MainViewModel,
onEnrollClick: () -> Unit,
onShowDecryptionClick: () -> Unit
onShowDecryptionClick: () -> Unit,
) {
val uiState = viewModel.uiState.collectAsState()
Log.d("StylishLoginScreen: ","Recompose")
val context = LocalContext.current

Log.d("StylishLoginScreen: ", "Recompose")
Box(
modifier = modifier
.fillMaxSize().padding(16.dp),
.fillMaxSize()
.padding(16.dp),
contentAlignment = Alignment.Center
) {

LaunchedEffect(Unit) {
viewModel.feedback.collect { messageResId ->
showToastMessage(context, messageResId)
}
}

Column(
modifier = Modifier
.fillMaxWidth()
Expand Down Expand Up @@ -320,7 +375,7 @@ fun StylishLoginScreen(
}

@Composable
private fun DecryptedPassword(uiState: LoginUIState) {
fun DecryptedPassword(uiState: LoginUIState) {
Text(
text = "Decrypted Password:",
color = Color(0xFFFFFFFF),
Expand All @@ -344,7 +399,7 @@ private fun DecryptedPassword(uiState: LoginUIState) {
}

@Composable
private fun StyledButton(text: String, painterId: Int, colorId: Long, onClick: () -> Unit) {
fun StyledButton(text: String, painterId: Int, colorId: Long, onClick: () -> Unit) {
Button(
onClick = onClick,
modifier = Modifier
Expand Down Expand Up @@ -413,6 +468,9 @@ fun TextFieldWithIcon(
}
}

private fun showToastMessage(context: Context, messageResId: Int, extraMessage: String? = null) {
Toast.makeText(context, context.getString(messageResId, extraMessage), Toast.LENGTH_SHORT).show()
}

@Preview(showBackground = true)
@Composable
Expand Down
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