Allow to unlock with biometric authentication

Issue: #11

app/src/main/AndroidManifest.xml

@@ -6,6 +6,8 @@
     xmlns:tools="http://schemas.android.com/tools"
     package="exe.bbllw8.anemo">
 
+    <uses-permission android:name="android.permission.USE_BIOMETRIC" />
+
     <application
         android:allowBackup="true"
         android:allowClearUserData="false"

app/src/main/java/exe/bbllw8/anemo/config/ConfigurationActivity.java

@@ -7,6 +7,7 @@
 import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
+import android.view.View;
 import android.widget.Switch;
 import android.widget.TextView;
 
@@ -25,6 +26,7 @@ public final class ConfigurationActivity extends Activity {
 
     private TextView passwordSetView;
     private TextView changeLockView;
+    private Switch biometricSwitch;
 
     private LockStore lockStore;
 
@@ -44,8 +46,6 @@ protected void onCreate(@Nullable Bundle savedInstanceState) {
         shortcutSwitch.setOnCheckedChangeListener(
                 (v, isChecked) -> AnemoShell.setEnabled(getApplication(), isChecked));
 
-        setupPasswordViews();
-
         changeLockView = findViewById(R.id.configuration_lock);
         changeLockView.setText(lockStore.isLocked()
                 ? R.string.configuration_storage_unlock
@@ -62,6 +62,15 @@ protected void onCreate(@Nullable Bundle savedInstanceState) {
         autoLockSwitch.setChecked(lockStore.isAutoLockEnabled());
         autoLockSwitch.setOnCheckedChangeListener(
                 (v, isChecked) -> lockStore.setAutoLockEnabled(isChecked));
+
+        biometricSwitch = findViewById(R.id.configuration_biometric_unlock);
+        biometricSwitch
+                .setVisibility(lockStore.canAuthenticateBiometric() ? View.VISIBLE : View.GONE);
+        biometricSwitch.setChecked(lockStore.isBiometricUnlockEnabled());
+        biometricSwitch.setOnCheckedChangeListener(
+                (v, isChecked) -> lockStore.setBiometricUnlockEnabled(isChecked));
+
+        setupPasswordViews();
     }
 
     @Override
@@ -81,11 +90,14 @@ private void setupPasswordViews() {
             passwordSetView.setOnClickListener(
                     $ -> new SetPasswordDialog(this, lockStore, this::setupPasswordViews).show());
         }
-        passwordSetView.setEnabled(!lockStore.isLocked());
+        final boolean enableViews = !lockStore.isLocked();
+        passwordSetView.setEnabled(enableViews);
+        biometricSwitch.setEnabled(enableViews);
     }
 
     private final Consumer<Boolean> onLockChanged = isLocked -> {
         passwordSetView.setEnabled(!isLocked);
+        biometricSwitch.setEnabled(!isLocked);
         changeLockView.setText(isLocked
                 ? R.string.configuration_storage_unlock
                 : R.string.configuration_storage_lock);

app/src/main/java/exe/bbllw8/anemo/lock/LockStore.java

@@ -9,6 +9,8 @@
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.SharedPreferences;
+import android.hardware.biometrics.BiometricManager;
+import android.os.Build;
 import android.util.Log;
 
 import androidx.annotation.NonNull;
@@ -28,6 +30,7 @@ public final class LockStore implements SharedPreferences.OnSharedPreferenceChan
     private static final String KEY_LOCK = "is_locked";
     private static final String KEY_PASSWORD = "password_hash";
     private static final String KEY_AUTO_LOCK = "auto_lock";
+    private static final String KEY_BIOMETRIC_UNLOCK = "biometric_unlock";
     private static final boolean DEFAULT_LOCK_VALUE = false;
     private static final boolean DEFAULT_AUTO_LOCK_VALUE = false;
 
@@ -39,6 +42,7 @@ public final class LockStore implements SharedPreferences.OnSharedPreferenceChan
 
     private final SharedPreferences preferences;
     private final List<Consumer<Boolean>> listeners = new ArrayList<>();
+    private final BiometricManager biometricManager;
 
     private final JobScheduler jobScheduler;
     private final ComponentName autoLockComponent;
@@ -61,6 +65,9 @@ private LockStore(Context context) {
         preferences.registerOnSharedPreferenceChangeListener(this);
 
         jobScheduler = context.getSystemService(JobScheduler.class);
+        biometricManager = Build.VERSION.SDK_INT >= 29
+                ? context.getSystemService(BiometricManager.class)
+                : null;
         autoLockComponent = new ComponentName(context, AutoLockJobService.class);
     }
 
@@ -134,6 +141,19 @@ public synchronized void setAutoLockEnabled(boolean enabled) {
         }
     }
 
+    public boolean canAuthenticateBiometric() {
+        return Build.VERSION.SDK_INT >= 29 && biometricManager != null
+                && biometricManager.canAuthenticate() == BiometricManager.BIOMETRIC_SUCCESS;
+    }
+
+    public synchronized boolean isBiometricUnlockEnabled() {
+        return canAuthenticateBiometric() && preferences.getBoolean(KEY_BIOMETRIC_UNLOCK, false);
+    }
+
+    public synchronized void setBiometricUnlockEnabled(boolean enabled) {
+        preferences.edit().putBoolean(KEY_BIOMETRIC_UNLOCK, enabled).apply();
+    }
+
     public void addListener(Consumer<Boolean> listener) {
         synchronized (listeners) {
             listeners.add(listener);

app/src/main/java/exe/bbllw8/anemo/lock/UnlockActivity.java

@@ -6,12 +6,17 @@
 
 import android.app.Activity;
 import android.content.Intent;
+import android.hardware.biometrics.BiometricPrompt;
 import android.os.Bundle;
+import android.os.CancellationSignal;
 import android.widget.Button;
 import android.widget.EditText;
 import android.widget.ImageView;
 
 import androidx.annotation.Nullable;
+import androidx.annotation.RequiresApi;
+
+import java.util.concurrent.Executor;
 
 import exe.bbllw8.anemo.R;
 import exe.bbllw8.anemo.config.ConfigurationActivity;
@@ -32,7 +37,11 @@ protected void onCreate(@Nullable Bundle savedInstanceState) {
         lockStore = LockStore.getInstance(this);
         onUnlocked = getOnUnlocked(getIntent());
         if (lockStore.hasPassword()) {
-            setupUI();
+            if (lockStore.isBiometricUnlockEnabled()) {
+                unlockViaBiometricAuthentication();
+            } else {
+                setupUI();
+            }
         } else {
             doUnlock();
         }
@@ -52,6 +61,7 @@ private void setupUI() {
 
         configBtn.setOnClickListener(v -> {
             startActivity(new Intent(this, ConfigurationActivity.class));
+            setResult(Activity.RESULT_CANCELED);
             finish();
         });
 
@@ -76,6 +86,34 @@ private void doUnlock() {
         onUnlocked.run();
     }
 
+    @RequiresApi(29)
+    private void unlockViaBiometricAuthentication() {
+        final Executor executor = getMainExecutor();
+        final CancellationSignal cancellationSignal = new CancellationSignal();
+        cancellationSignal.setOnCancelListener(this::finish);
+
+        final BiometricPrompt prompt = new BiometricPrompt.Builder(this)
+                .setTitle(getString(R.string.tile_unlock))
+                .setDescription(getString(R.string.password_input_biometric_message))
+                .setNegativeButton(getString(R.string.password_input_biometric_fallback), executor,
+                        (dialog, which) -> setupUI())
+                .build();
+        prompt.authenticate(cancellationSignal, executor,
+                new BiometricPrompt.AuthenticationCallback() {
+                    @Override
+                    public void onAuthenticationSucceeded(
+                            BiometricPrompt.AuthenticationResult result) {
+                        doUnlock();
+                    }
+
+                    @Override
+                    public void onAuthenticationFailed() {
+                        setResult(Activity.RESULT_CANCELED);
+                        finish();
+                    }
+                });
+    }
+
     private Runnable getOnUnlocked(Intent intent) {
         if (intent.getBooleanExtra(OPEN_AFTER_UNLOCK, false)) {
             return () -> {

app/src/main/res/layout/configuration.xml

@@ -64,5 +64,15 @@
             android:paddingHorizontal="16dp"
             android:text="@string/configuration_storage_lock_auto"
             android:textSize="16sp" />
+
+        <Switch
+            android:id="@+id/configuration_biometric_unlock"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:foreground="?android:attr/selectableItemBackground"
+            android:minHeight="56dp"
+            android:paddingHorizontal="16dp"
+            android:text="@string/configuration_storage_unlock_biometric"
+            android:textSize="16sp" />
     </LinearLayout>
 </ScrollView>

app/src/main/res/values/strings.xml

@@ -20,6 +20,8 @@
 
     <string name="password_input_message">Type your Anemo password to unlock the Anemo Storage</string>
     <string name="password_input_action">Unlock</string>
+    <string name="password_input_biometric_message">Authenticate to unlock the Anemo Storage</string>
+    <string name="password_input_biometric_fallback">Use password</string>
 
     <string name="password_set_title">Add password protection</string>
     <string name="password_set_message">Set a password to lock the access to the Anemo Storage</string>
@@ -59,5 +61,6 @@
     <string name="configuration_password_change">Change password</string>
     <string name="configuration_storage_lock">Lock storage access</string>
     <string name="configuration_storage_unlock">Unlock storage access</string>
+    <string name="configuration_storage_unlock_biometric">Allow storage unlock with biometric access</string>
     <string name="configuration_storage_lock_auto">Automatically lock access after 15 minutes</string>
 </resources>