Merge branch 'master' into 'preference-switches'

# Conflicts: # briar-android/src/main/java/org/briarproject/briar/android/settings/SettingsFragment.java
2026-02-12 18:59:06 +01:00 · 2018-08-14 09:59:22 +00:00
parent 30a070dd13 42031631dd
commit 03191ff08f
52 changed files with 632 additions and 119 deletions
--- a/briar-android/build.gradle
+++ b/briar-android/build.gradle
@@ -40,9 +40,9 @@ dependencies {

 	testImplementation project(path: ':bramble-api', configuration: 'testOutput')
 	testImplementation project(path: ':bramble-core', configuration: 'testOutput')
-	testImplementation 'org.robolectric:robolectric:3.5.1'
-	testImplementation 'org.robolectric:shadows-support-v4:3.0'
-	testImplementation 'org.mockito:mockito-core:2.8.9'
+	testImplementation 'org.robolectric:robolectric:3.8'
+	testImplementation 'org.robolectric:shadows-support-v4:3.3.2'
+	testImplementation 'org.mockito:mockito-core:2.13.0'
 	testImplementation 'junit:junit:4.12'
 	testImplementation "org.jmock:jmock:2.8.2"
 	testImplementation "org.jmock:jmock-junit4:2.8.2"
@@ -165,8 +165,8 @@ dependencyVerification {
 			'junit:junit:4.12:junit-4.12.jar:59721f0805e223d84b90677887d9ff567dc534d7c502ca903c0c2b17f05c116a',
 			'nekohtml:nekohtml:1.9.6.2:nekohtml-1.9.6.2.jar:fdff6cfa9ed9cc911c842a5d2395f209ec621ef1239d46810e9e495809d3ae09',
 			'nekohtml:xercesMinimal:1.9.6.2:xercesMinimal-1.9.6.2.jar:95b8b357d19f63797dd7d67622fd3f18374d64acbc6584faba1c7759a31e8438',
-			'net.bytebuddy:byte-buddy-agent:1.6.14:byte-buddy-agent-1.6.14.jar:c141a2d6809c3eeff4a43d25992826abccebdd4b793af3e7a5f346e88ae73a33',
-			'net.bytebuddy:byte-buddy:1.6.14:byte-buddy-1.6.14.jar:917758b3c651e278a15a029ba1d42dbf802d8b0e1fe2aa4b81c5750c64f461c1',
+			'net.bytebuddy:byte-buddy-agent:1.7.9:byte-buddy-agent-1.7.9.jar:ac1a993befb528c3271a83a9ad9c42d363d399e9deb26e0470e3c4962066c550',
+			'net.bytebuddy:byte-buddy:1.7.9:byte-buddy-1.7.9.jar:2ea2ada12b790d16ac7f6e6c065cb55cbcdb6ba519355f5958851159cad3b16a',
 			'net.sf.jopt-simple:jopt-simple:4.9:jopt-simple-4.9.jar:26c5856e954b5f864db76f13b86919b59c6eecf9fd930b96baa8884626baf2f5',
 			'net.sf.kxml:kxml2:2.3.0:kxml2-2.3.0.jar:f264dd9f79a1fde10ce5ecc53221eff24be4c9331c830b7d52f2f08a7b633de2',
 			'org.apache.ant:ant-launcher:1.9.4:ant-launcher-1.9.4.jar:7bccea20b41801ca17bcbc909a78c835d0f443f12d639c77bd6ae3d05861608d',
@@ -215,8 +215,8 @@ dependencyVerification {
 			'org.jmock:jmock-testjar:2.8.2:jmock-testjar-2.8.2.jar:8900860f72c474e027cf97fe78dcbf154a1aa7fc62b6845c5fb4e4f3c7bc8760',
 			'org.jmock:jmock:2.8.2:jmock-2.8.2.jar:6c73cb4a2e6dbfb61fd99c9a768539c170ab6568e57846bd60dbf19596b65b16',
 			'org.jvnet.staxex:stax-ex:1.7.7:stax-ex-1.7.7.jar:a31ff7d77163c0deb09e7fee59ad35ae44c2cee2cc8552a116ccd1583d813fb4',
-			'org.mockito:mockito-core:2.8.9:mockito-core-2.8.9.jar:a2bb9b8b40d81bb02ccb84259524c0f4911f73c6577bfc7ddd940b8fc729b6e6',
-			'org.objenesis:objenesis:2.5:objenesis-2.5.jar:293328e1b0d31ed30bb89fca542b6c52fac00989bb0e62eb9d98d630c4dd6b7c',
+			'org.mockito:mockito-core:2.13.0:mockito-core-2.13.0.jar:92a746b37cf8c5730a5e7b35fd7d8cd72700089435ff92ee03ed8384d4eb3377',
+			'org.objenesis:objenesis:2.6:objenesis-2.6.jar:5e168368fbc250af3c79aa5fef0c3467a2d64e5a7bd74005f25d8399aeb0708d',
 			'org.ow2.asm:asm-analysis:5.1:asm-analysis-5.1.jar:a34658f5c5de4b573eef21131cc32cc25f7b66407944f312b28ec2e56abb1fa9',
 			'org.ow2.asm:asm-commons:5.0.1:asm-commons-5.0.1.jar:fb1cb7fa27d892712ced8fbf8d027eb5052ecd3999dba1ba47824357accb40e7',
 			'org.ow2.asm:asm-commons:5.1:asm-commons-5.1.jar:97b3786e1f55e74bddf8ad102bf50e33bbcbc1f6b7fd7b36f0bbbb25cd4981be',
@@ -225,15 +225,15 @@ dependencyVerification {
 			'org.ow2.asm:asm-util:5.1:asm-util-5.1.jar:ee032c39ae5e3cd099148fbba9a2124f9ed613e5cb93e03ee0fa8808ce364040',
 			'org.ow2.asm:asm:5.0.4:asm-5.0.4.jar:896618ed8ae62702521a78bc7be42b7c491a08e6920a15f89a3ecdec31e9a220',
 			'org.ow2.asm:asm:5.1:asm-5.1.jar:d2da399a9967c69f0a21739256fa79d284222c223082cacadc17372244764b54',
-			'org.robolectric:annotations:3.5.1:annotations-3.5.1.jar:14db0f7d2299c5400ff7764bb37b4fa80306582d8965fdf6999091723e2384ce',
-			'org.robolectric:junit:3.5.1:junit-3.5.1.jar:b2e81b7d5a22755f2ea76aa9bbbd4359d61c4cb9577193ccfbb8f97378ed293b',
-			'org.robolectric:resources:3.5.1:resources-3.5.1.jar:22a5564590c8bfd8df7efb2b0c7d9942b46a0beb59ba38899d59c1270f293b1c',
-			'org.robolectric:robolectric:3.5.1:robolectric-3.5.1.jar:603cf898f93b854f18021fab452aca3fe482368eeb2e720988ae82212ebcf4b6',
-			'org.robolectric:sandbox:3.5.1:sandbox-3.5.1.jar:beff8c3c1e840e0f7f78aadef170f347bae349f098babfc176765f499a4bcbb5',
-			'org.robolectric:shadowapi:3.5.1:shadowapi-3.5.1.jar:6d574f9ae0922791eb8f06979f0010997d4b862c7aec96d485ae797ddfc13278',
-			'org.robolectric:shadows-framework:3.5.1:shadows-framework-3.5.1.jar:597b54cc1a494799d783921c6ac04352f33e94fca8e00f299d4ca192db79e3fc',
-			'org.robolectric:shadows-support-v4:3.0:shadows-support-v4-3.0.jar:66bcc3257b037d72998e860d67b1bc58215b7eeac8ad860fcc3e613332d88619',
-			'org.robolectric:utils:3.5.1:utils-3.5.1.jar:d7d77326867e6d903156ebb18c244819b26aebe3aa82a1c57081081a0b6c4f63',
+			'org.robolectric:annotations:3.8:annotations-3.8.jar:8eab08facfe2a8cd22f6a09f4378f012a5985c0d4f4ad4e203e00f75b5568458',
+			'org.robolectric:junit:3.8:junit-3.8.jar:042575dbc95dc82ec046d13438ccda578917ce786d2f464cba0eb18da1f412cb',
+			'org.robolectric:resources:3.8:resources-3.8.jar:6d11e6d39df8eda837c52319cf8d6bef424df45be6f29b3a731707832eb6ffc1',
+			'org.robolectric:robolectric:3.8:robolectric-3.8.jar:34908fc858e6e4113be2cf97fe55d3ffa4462bf7183d466542582ca1898ce60a',
+			'org.robolectric:sandbox:3.8:sandbox-3.8.jar:cc257dc75c5af9e62a43572ac89dff4d8520427307cf973e6b663c88fb000720',
+			'org.robolectric:shadowapi:3.8:shadowapi-3.8.jar:28bc24cb5c4b4030852cebebfd5f12536d03088892cb3c8b1d1379297087aca8',
+			'org.robolectric:shadows-framework:3.8:shadows-framework-3.8.jar:83548db7249edf1af87e1a1f4d8f4eec3e85d6220161da601e6f6398476911b2',
+			'org.robolectric:shadows-support-v4:3.3.2:shadows-support-v4-3.3.2.jar:6f689264738266e70fe08db7c04b7b5a75155994f4e3f7f311960d90486bf005',
+			'org.robolectric:utils:3.8:utils-3.8.jar:e945d04d40e37554e02d4be1bc3abf9bede45375c843aa36d10ccb6b63edbf34',
 			'tools.fastlane:screengrab:1.1.0:screengrab-1.1.0.aar:03ce3868ee8a0082d14e7a1de0999f91531c0cc794392688beb08ee9bc4495fd',
 			'uk.co.samuelwall:material-tap-target-prompt:2.8.0:material-tap-target-prompt-2.8.0.aar:ac70770c05bbc4675a1d5712c0e53d46ee4fa961b74947589fce50d8003065ec',
 			'xmlpull:xmlpull:1.1.3.1:xmlpull-1.1.3.1.jar:34e08ee62116071cbb69c0ed70d15a7a5b208d62798c59f2120bb8929324cb63',
--- a/briar-android/src/main/AndroidManifest.xml
+++ b/briar-android/src/main/AndroidManifest.xml
@@ -402,5 +402,11 @@
 			android:theme="@android:style/Theme.NoDisplay">
 		</activity>

+		<activity
+			android:name=".android.login.UnlockActivity"
+			android:label="@string/lock_unlock"
+			android:launchMode="singleTask"
+			android:theme="@style/BriarTheme.NoActionBar"/>
+
 	</application>
 </manifest>
--- a/briar-android/src/main/java/org/briarproject/briar/android/AndroidComponent.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/AndroidComponent.java
@@ -28,6 +28,7 @@ import org.briarproject.briar.android.login.SignInReminderReceiver;
 import org.briarproject.briar.android.reporting.BriarReportSender;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.android.DozeWatchdog;
+import org.briarproject.briar.api.android.LockManager;
 import org.briarproject.briar.api.android.ScreenFilterMonitor;
 import org.briarproject.briar.api.blog.BlogManager;
 import org.briarproject.briar.api.blog.BlogPostFactory;
@@ -146,6 +147,8 @@ public interface AndroidComponent

 	AccountManager accountManager();

+	LockManager lockManager();
+
 	void inject(SignInReminderReceiver briarService);

 	void inject(BriarService briarService);
--- a/briar-android/src/main/java/org/briarproject/briar/android/AndroidNotificationManagerImpl.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/AndroidNotificationManagerImpl.java
@@ -2,6 +2,7 @@ package org.briarproject.briar.android;

 import android.annotation.TargetApi;
 import android.app.Application;
+import android.app.Notification;
 import android.app.NotificationChannel;
 import android.app.NotificationManager;
 import android.app.PendingIntent;
@@ -12,7 +13,6 @@ import android.support.annotation.StringRes;
 import android.support.annotation.UiThread;
 import android.support.v4.app.NotificationCompat;
 import android.support.v4.app.TaskStackBuilder;
-import android.support.v4.content.ContextCompat;

 import org.briarproject.bramble.api.Multiset;
 import org.briarproject.bramble.api.contact.ContactId;
@@ -65,7 +65,6 @@ import javax.inject.Inject;
 import static android.app.Notification.DEFAULT_LIGHTS;
 import static android.app.Notification.DEFAULT_SOUND;
 import static android.app.Notification.DEFAULT_VIBRATE;
-import static android.app.Notification.VISIBILITY_SECRET;
 import static android.app.NotificationManager.IMPORTANCE_DEFAULT;
 import static android.app.NotificationManager.IMPORTANCE_LOW;
 import static android.content.Context.NOTIFICATION_SERVICE;
@@ -73,8 +72,12 @@ import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.support.v4.app.NotificationCompat.CATEGORY_MESSAGE;
+import static android.support.v4.app.NotificationCompat.CATEGORY_SERVICE;
 import static android.support.v4.app.NotificationCompat.CATEGORY_SOCIAL;
 import static android.support.v4.app.NotificationCompat.PRIORITY_LOW;
+import static android.support.v4.app.NotificationCompat.PRIORITY_MIN;
+import static android.support.v4.app.NotificationCompat.VISIBILITY_SECRET;
+import static android.support.v4.content.ContextCompat.getColor;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
@@ -173,8 +176,7 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 		nc.setLockscreenVisibility(VISIBILITY_SECRET);
 		nc.enableVibration(true);
 		nc.enableLights(true);
-		nc.setLightColor(
-				ContextCompat.getColor(appContext, R.color.briar_green_light));
+		nc.setLightColor(getColor(appContext, R.color.briar_green_light));
 		notificationManager.createNotificationChannel(nc);
 	}

@@ -271,6 +273,47 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 		});
 	}

+	@UiThread
+	@Override
+	public Notification getForegroundNotification() {
+		return getForegroundNotification(false);
+	}
+
+	@UiThread
+	private Notification getForegroundNotification(boolean locked) {
+		int title = locked ? R.string.lock_is_locked :
+				R.string.ongoing_notification_title;
+		int text = locked ? R.string.lock_tap_to_unlock :
+				R.string.ongoing_notification_text;
+		int icon = locked ? R.drawable.startup_lock :
+				R.drawable.notification_ongoing;
+		// Ongoing foreground notification that shows BriarService is running
+		NotificationCompat.Builder b =
+				new NotificationCompat.Builder(appContext, ONGOING_CHANNEL_ID);
+		b.setSmallIcon(icon);
+		b.setColor(getColor(appContext, R.color.briar_primary));
+		b.setContentTitle(appContext.getText(title));
+		b.setContentText(appContext.getText(text));
+		b.setWhen(0); // Don't show the time
+		b.setOngoing(true);
+		Intent i = new Intent(appContext, NavDrawerActivity.class);
+		i.setFlags(FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TOP);
+		b.setContentIntent(PendingIntent.getActivity(appContext, 0, i, 0));
+		if (SDK_INT >= 21) {
+			b.setCategory(CATEGORY_SERVICE);
+			b.setVisibility(VISIBILITY_SECRET);
+		}
+		b.setPriority(PRIORITY_MIN);
+		return b.build();
+	}
+
+	@UiThread
+	@Override
+	public void updateForegroundNotification(boolean locked) {
+		Notification n = getForegroundNotification(locked);
+		notificationManager.notify(ONGOING_NOTIFICATION_ID, n);
+	}
+
 	private void showContactNotification(ContactId c) {
 		androidExecutor.runOnUiThread(() -> {
 			if (blockContacts) return;
@@ -636,7 +679,7 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 		NotificationCompat.Builder b =
 				new NotificationCompat.Builder(appContext, REMINDER_CHANNEL_ID);
 		b.setSmallIcon(R.drawable.ic_signout);
-		b.setColor(ContextCompat.getColor(appContext, R.color.briar_primary));
+		b.setColor(getColor(appContext, R.color.briar_primary));
 		b.setContentTitle(
 				appContext.getText(R.string.reminder_notification_title));
 		b.setContentText(
--- a/briar-android/src/main/java/org/briarproject/briar/android/AppModule.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/AppModule.java
@@ -29,8 +29,10 @@ import org.briarproject.bramble.plugin.tor.AndroidTorPluginFactory;
 import org.briarproject.bramble.plugin.tor.CircumventionProvider;
 import org.briarproject.bramble.util.AndroidUtils;
 import org.briarproject.bramble.util.StringUtils;
+import org.briarproject.briar.android.account.LockManagerImpl;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.android.DozeWatchdog;
+import org.briarproject.briar.api.android.LockManager;
 import org.briarproject.briar.api.android.ScreenFilterMonitor;

 import java.io.File;
@@ -200,4 +202,13 @@ public class AppModule {
 		return dozeWatchdog;
 	}

+	@Provides
+	@Singleton
+	LockManager provideLockManager(LifecycleManager lifecycleManager,
+			EventBus eventBus, LockManagerImpl lockManager) {
+		lifecycleManager.registerService(lockManager);
+		eventBus.addListener(lockManager);
+		return lockManager;
+	}
+
 }
--- a/briar-android/src/main/java/org/briarproject/briar/android/BriarService.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/BriarService.java
@@ -2,6 +2,7 @@ package org.briarproject.briar.android;

 import android.app.ActivityManager;
 import android.app.ActivityManager.RunningAppProcessInfo;
+import android.app.Notification;
 import android.app.NotificationChannel;
 import android.app.NotificationManager;
 import android.app.PendingIntent;
@@ -15,7 +16,6 @@ import android.content.ServiceConnection;
 import android.os.Binder;
 import android.os.IBinder;
 import android.support.v4.app.NotificationCompat;
-import android.support.v4.content.ContextCompat;

 import org.briarproject.bramble.api.account.AccountManager;
 import org.briarproject.bramble.api.crypto.SecretKey;
@@ -25,6 +25,7 @@ import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.logout.HideUiActivity;
 import org.briarproject.briar.android.navdrawer.NavDrawerActivity;
+import org.briarproject.briar.api.android.AndroidNotificationManager;

 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -44,8 +45,6 @@ import static android.content.Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
 import static android.content.Intent.FLAG_ACTIVITY_NO_ANIMATION;
 import static android.os.Build.VERSION.SDK_INT;
-import static android.support.v4.app.NotificationCompat.CATEGORY_SERVICE;
-import static android.support.v4.app.NotificationCompat.PRIORITY_MIN;
 import static android.support.v4.app.NotificationCompat.VISIBILITY_SECRET;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
@@ -74,6 +73,8 @@ public class BriarService extends Service {
 	@Nullable
 	private BroadcastReceiver receiver = null;

+	@Inject
+	AndroidNotificationManager notificationManager;
 	@Inject
 	AccountManager accountManager;

@@ -121,24 +122,9 @@ public class BriarService extends Service {
 			failureChannel.setLockscreenVisibility(VISIBILITY_SECRET);
 			nm.createNotificationChannel(failureChannel);
 		}
-		// Show an ongoing notification that the service is running
-		NotificationCompat.Builder b =
-				new NotificationCompat.Builder(this, ONGOING_CHANNEL_ID);
-		b.setSmallIcon(R.drawable.notification_ongoing);
-		b.setColor(ContextCompat.getColor(this, R.color.briar_primary));
-		b.setContentTitle(getText(R.string.ongoing_notification_title));
-		b.setContentText(getText(R.string.ongoing_notification_text));
-		b.setWhen(0); // Don't show the time
-		b.setOngoing(true);
-		Intent i = new Intent(this, NavDrawerActivity.class);
-		i.setFlags(FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TOP);
-		b.setContentIntent(PendingIntent.getActivity(this, 0, i, 0));
-		if (SDK_INT >= 21) {
-			b.setCategory(CATEGORY_SERVICE);
-			b.setVisibility(VISIBILITY_SECRET);
-		}
-		b.setPriority(PRIORITY_MIN);
-		startForeground(ONGOING_NOTIFICATION_ID, b.build());
+		Notification foregroundNotification =
+				notificationManager.getForegroundNotification();
+		startForeground(ONGOING_NOTIFICATION_ID, foregroundNotification);
 		// Start the services in a background thread
 		new Thread(() -> {
 			StartResult result = lifecycleManager.startServices(dbKey);
--- a/briar-android/src/main/java/org/briarproject/briar/android/TestingConstants.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/TestingConstants.java
@@ -40,4 +40,9 @@ public interface TestingConstants {
 	 * Feature flag for enabling the sign-in reminder in release builds.
 	 */
 	boolean FEATURE_FLAG_SIGN_IN_REMINDER = IS_DEBUG_BUILD;
+
+	/**
+	 * Feature flag for enabling the PIN lock in release builds.
+	 */
+	boolean FEATURE_FLAG_PIN_LOCK = IS_DEBUG_BUILD;
 }
--- a/briar-android/src/main/java/org/briarproject/briar/android/account/LockManagerImpl.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/account/LockManagerImpl.java
@@ -0,0 +1,132 @@
+package org.briarproject.briar.android.account;
+
+import android.app.Application;
+import android.arch.lifecycle.LiveData;
+import android.arch.lifecycle.MutableLiveData;
+import android.content.Context;
+import android.support.annotation.UiThread;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.lifecycle.Service;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.settings.SettingsManager;
+import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.android.LockManager;
+
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.ThreadSafe;
+import javax.inject.Inject;
+
+import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.briar.android.settings.SettingsFragment.PREF_SCREEN_LOCK;
+import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_NAMESPACE;
+import static org.briarproject.briar.android.util.UiUtils.hasScreenLock;
+
+@ThreadSafe
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class LockManagerImpl implements LockManager, Service, EventListener {
+
+	private static final Logger LOG =
+			Logger.getLogger(LockManagerImpl.class.getName());
+
+	private final Context appContext;
+	private final SettingsManager settingsManager;
+	private final AndroidNotificationManager notificationManager;
+	@DatabaseExecutor
+	private final Executor dbExecutor;
+
+	private volatile boolean locked = false;
+	private volatile boolean lockableSetting = false;
+	private final MutableLiveData<Boolean> lockable = new MutableLiveData<>();
+
+	@Inject
+	public LockManagerImpl(Application app, SettingsManager settingsManager,
+			AndroidNotificationManager notificationManager,
+			@DatabaseExecutor Executor dbExecutor) {
+		this.appContext = app.getApplicationContext();
+		this.settingsManager = settingsManager;
+		this.notificationManager = notificationManager;
+		this.dbExecutor = dbExecutor;
+
+		// setting this in the constructor makes #getValue() @NonNull
+		this.lockable.setValue(false);
+	}
+
+	@Override
+	public void startService() {
+		// only load the setting here, because database isn't open before
+		loadLockableSetting();
+	}
+
+	@Override
+	public void stopService() {
+	}
+
+	@Override
+	public LiveData<Boolean> isLockable() {
+		return lockable;
+	}
+
+	@UiThread
+	@Override
+	public void checkIfLockable() {
+		boolean oldValue = lockable.getValue();
+		boolean newValue = hasScreenLock(appContext) && lockableSetting;
+		if (oldValue != newValue) {
+			this.lockable.setValue(newValue);
+		}
+	}
+
+	@Override
+	public boolean isLocked() {
+		if (locked && !hasScreenLock(appContext)) {
+			lockable.postValue(false);
+			locked = false;
+		}
+		return locked;
+	}
+
+	@Override
+	public void setLocked(boolean locked) {
+		this.locked = locked;
+		notificationManager.updateForegroundNotification(locked);
+	}
+
+	@Override
+	public void eventOccurred(Event event) {
+		if (event instanceof SettingsUpdatedEvent) {
+			SettingsUpdatedEvent e = (SettingsUpdatedEvent) event;
+			String namespace = e.getNamespace();
+			if (namespace.equals(SETTINGS_NAMESPACE)) {
+				loadLockableSetting();
+			}
+		}
+	}
+
+	private void loadLockableSetting() {
+		dbExecutor.execute(() -> {
+			try {
+				Settings settings =
+						settingsManager.getSettings(SETTINGS_NAMESPACE);
+				lockableSetting = settings.getBoolean(PREF_SCREEN_LOCK, false);
+				boolean newValue = hasScreenLock(appContext) && lockableSetting;
+				lockable.postValue(newValue);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				lockableSetting = false;
+				lockable.postValue(false);
+			}
+		});
+	}
+
+}
--- a/briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java
@@ -37,6 +37,7 @@ import org.briarproject.briar.android.login.OpenDatabaseActivity;
 import org.briarproject.briar.android.login.PasswordActivity;
 import org.briarproject.briar.android.login.PasswordFragment;
 import org.briarproject.briar.android.login.SetupActivity;
+import org.briarproject.briar.android.login.UnlockActivity;
 import org.briarproject.briar.android.navdrawer.NavDrawerActivity;
 import org.briarproject.briar.android.panic.PanicPreferencesActivity;
 import org.briarproject.briar.android.panic.PanicResponderActivity;
@@ -163,6 +164,8 @@ public interface ActivityComponent {

 	void inject(StartupFailureActivity activity);

+	void inject(UnlockActivity activity);
+
 	// Fragments
 	void inject(AuthorNameFragment fragment);

--- a/briar-android/src/main/java/org/briarproject/briar/android/activity/BriarActivity.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/activity/BriarActivity.java
@@ -16,7 +16,9 @@ import org.briarproject.briar.android.controller.BriarController;
 import org.briarproject.briar.android.controller.DbController;
 import org.briarproject.briar.android.controller.handler.UiResultHandler;
 import org.briarproject.briar.android.login.PasswordActivity;
+import org.briarproject.briar.android.login.UnlockActivity;
 import org.briarproject.briar.android.logout.ExitActivity;
+import org.briarproject.briar.api.android.LockManager;

 import java.util.logging.Logger;

@@ -30,6 +32,7 @@ import static android.content.Intent.FLAG_ACTIVITY_NO_ANIMATION;
 import static android.os.Build.VERSION.SDK_INT;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_DOZE_WHITELISTING;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PASSWORD;
+import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_UNLOCK;
 import static org.briarproject.briar.android.util.UiUtils.getDozeWhitelistingIntent;
 import static org.briarproject.briar.android.util.UiUtils.isSamsung7;

@@ -44,26 +47,43 @@ public abstract class BriarActivity extends BaseActivity {

 	@Inject
 	BriarController briarController;
-
 	@Deprecated
 	@Inject
 	DbController dbController;
+	@Inject
+	protected LockManager lockManager;

 	@Override
 	protected void onActivityResult(int request, int result, Intent data) {
 		super.onActivityResult(request, result, data);
-		if (request == REQUEST_PASSWORD) {
-			if (result == RESULT_OK) briarController.startAndBindService();
-			else supportFinishAfterTransition();
+		if (request == REQUEST_PASSWORD && result == RESULT_OK) {
+			// PasswordActivity finishes when password was entered correctly.
+			// When back button is pressed there, it will bring itself back,
+			// so that we never arrive here with a result that is not OK.
+			briarController.startAndBindService();
+		} else if (request == REQUEST_UNLOCK && result != RESULT_OK) {
+			// We arrive here, if the user presses 'back'
+			// in the Keyguard unlock screen, because UnlockActivity finishes.
+			// If we don't finish here, isFinishing will be false in onResume()
+			// and we launch a new UnlockActivity causing a loop.
+			supportFinishAfterTransition();
+			// If the result is OK, we don't need to do anything here
+			// and can resume normally.
 		}
 	}

 	@Override
-	public void onStart() {
-		super.onStart();
-		if (!briarController.accountSignedIn() && !isFinishing()) {
+	public void onResume() {
+		super.onResume();
+		if (!briarController.accountSignedIn()) {
 			Intent i = new Intent(this, PasswordActivity.class);
 			startActivityForResult(i, REQUEST_PASSWORD);
+		} else if (lockManager.isLocked() && !isFinishing()) {
+			// Also check that the activity isn't finishing already.
+			// This is possible if finishing in onActivityResult().
+			// Failure to do this check would cause an UnlockActivity loop.
+			Intent i = new Intent(this, UnlockActivity.class);
+			startActivityForResult(i, REQUEST_UNLOCK);
 		} else if (SDK_INT >= 23) {
 			briarController.hasDozed(new UiResultHandler<Boolean>(this) {
 				@Override
--- a/briar-android/src/main/java/org/briarproject/briar/android/activity/RequestCodes.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/activity/RequestCodes.java
@@ -12,5 +12,7 @@ public interface RequestCodes {
 	int REQUEST_PERMISSION_CAMERA = 8;
 	int REQUEST_DOZE_WHITELISTING = 9;
 	int REQUEST_ENABLE_BLUETOOTH = 10;
+	int REQUEST_UNLOCK = 11;
+	int REQUEST_KEYGUARD_UNLOCK = 12;

 }
--- a/briar-android/src/main/java/org/briarproject/briar/android/login/PasswordActivity.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/login/PasswordActivity.java
@@ -23,8 +23,6 @@ import org.briarproject.briar.api.android.AndroidNotificationManager;

 import javax.inject.Inject;

-import static android.content.Intent.ACTION_MAIN;
-import static android.content.Intent.CATEGORY_HOME;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TASK;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
 import static android.view.View.INVISIBLE;
@@ -109,10 +107,9 @@ public class PasswordActivity extends BaseActivity {

 	@Override
 	public void onBackPressed() {
-		// Show the home screen rather than another password prompt
-		Intent intent = new Intent(ACTION_MAIN);
-		intent.addCategory(CATEGORY_HOME);
-		startActivity(intent);
+		// Move task and activity to the background instead of showing another
+		// password prompt. onActivityResult() won't be called in BriarActivity
+		moveTaskToBack(true);
 	}

 	private void deleteAccount() {
--- a/briar-android/src/main/java/org/briarproject/briar/android/login/UnlockActivity.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/login/UnlockActivity.java
@@ -0,0 +1,123 @@
+package org.briarproject.briar.android.login;
+
+import android.app.KeyguardManager;
+import android.content.Intent;
+import android.os.Bundle;
+import android.support.annotation.Nullable;
+import android.support.annotation.RequiresApi;
+import android.widget.Button;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.api.android.LockManager;
+
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import static android.os.Build.VERSION.SDK_INT;
+import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_KEYGUARD_UNLOCK;
+
+@RequiresApi(21)
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class UnlockActivity extends BaseActivity {
+
+	private static final Logger LOG =
+			Logger.getLogger(UnlockActivity.class.getName());
+	private static final String KEYGUARD_SHOWN = "keyguardShown";
+
+	@Inject
+	LockManager lockManager;
+
+	private boolean keyguardShown = false;
+
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	public void onCreate(@Nullable Bundle state) {
+		super.onCreate(state);
+		overridePendingTransition(0, 0);
+		setContentView(R.layout.activity_unlock);
+
+		Button button = findViewById(R.id.unlock);
+		button.setOnClickListener(view -> requestKeyguardUnlock());
+
+		keyguardShown = state != null && state.getBoolean(KEYGUARD_SHOWN);
+	}
+
+	@Override
+	protected void onSaveInstanceState(Bundle outState) {
+		super.onSaveInstanceState(outState);
+		// Saving whether we've shown the keyguard already is necessary
+		// for Android 6 when this activity gets destroyed.
+		//
+		// This will not help Android 5.
+		// There the system will show the keyguard once again.
+		// So if this activity was destroyed, the user needs to enter PIN twice.
+		outState.putBoolean(KEYGUARD_SHOWN, keyguardShown);
+	}
+
+	@Override
+	protected void onActivityResult(int requestCode, int resultCode,
+			Intent data) {
+		super.onActivityResult(requestCode, resultCode, data);
+		if (requestCode == REQUEST_KEYGUARD_UNLOCK) {
+			if (resultCode == RESULT_OK) unlock();
+			else {
+				finish();
+				overridePendingTransition(0, 0);
+			}
+		}
+	}
+
+	@Override
+	protected void onResume() {
+		super.onResume();
+		// Show keyguard after onActivityResult() as been called.
+		// Check if app is still locked, lockable
+		// and not finishing (which is possible if recreated)
+		if (!keyguardShown && lockManager.isLocked() && !isFinishing()) {
+			requestKeyguardUnlock();
+		} else if (!lockManager.isLocked()) {
+			setResult(RESULT_OK);
+			finish();
+		}
+	}
+
+	@Override
+	public void onBackPressed() {
+		moveTaskToBack(true);
+	}
+
+	private void requestKeyguardUnlock() {
+		KeyguardManager keyguardManager =
+				(KeyguardManager) getSystemService(KEYGUARD_SERVICE);
+		if (keyguardManager == null) throw new AssertionError();
+		Intent intent = keyguardManager.createConfirmDeviceCredentialIntent(
+				SDK_INT < 23 ? getString(R.string.lock_unlock_verbose) :
+						getString(R.string.lock_unlock), null);
+		if (intent == null) {
+			// the user must have removed the screen lock since locked
+			LOG.warning("Unlocking without keyguard");
+			unlock();
+		} else {
+			keyguardShown = true;
+			startActivityForResult(intent, REQUEST_KEYGUARD_UNLOCK);
+			overridePendingTransition(0, 0);
+		}
+	}
+
+	private void unlock() {
+		lockManager.setLocked(false);
+		setResult(RESULT_OK);
+		finish();
+		overridePendingTransition(0, 0);
+	}
+
+}
--- a/briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerActivity.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerActivity.java
@@ -7,6 +7,7 @@ import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.support.design.widget.NavigationView;
 import android.support.design.widget.NavigationView.OnNavigationItemSelectedListener;
+import android.support.v4.app.ActivityCompat;
 import android.support.v4.app.FragmentManager;
 import android.support.v4.app.FragmentTransaction;
 import android.support.v4.content.ContextCompat;
@@ -136,6 +137,8 @@ public class NavDrawerActivity extends BriarActivity implements
 		initializeTransports(getLayoutInflater());
 		transportsView.setAdapter(transportsAdapter);

+		lockManager.isLockable().observe(this, this::setLockVisible);
+
 		if (lifecycleManager.getLifecycleState().isAfter(RUNNING)) {
 			showSignOutFragment();
 		} else if (state == null) {
@@ -152,6 +155,7 @@ public class NavDrawerActivity extends BriarActivity implements
 	public void onStart() {
 		super.onStart();
 		updateTransports();
+		lockManager.checkIfLockable();
 		controller.showExpiryWarning(new UiResultHandler<ExpiryWarning>(this) {
 			@Override
 			public void onResultUi(ExpiryWarning expiry) {
@@ -213,9 +217,15 @@ public class NavDrawerActivity extends BriarActivity implements
 	public boolean onNavigationItemSelected(@NonNull MenuItem item) {
 		drawerLayout.closeDrawer(START);
 		clearBackStack();
-		loadFragment(item.getItemId());
-		// Don't display the Settings item as checked
-		return item.getItemId() != R.id.nav_btn_settings;
+		if (item.getItemId() == R.id.nav_btn_lock) {
+			lockManager.setLocked(true);
+			ActivityCompat.finishAfterTransition(this);
+			return false;
+		} else {
+			loadFragment(item.getItemId());
+			// Don't display the Settings item as checked
+			return item.getItemId() != R.id.nav_btn_settings;
+		}
 	}

 	@Override
@@ -301,6 +311,11 @@ public class NavDrawerActivity extends BriarActivity implements
 		// Do nothing for now
 	}

+	private void setLockVisible(boolean visible) {
+		MenuItem item = navigation.getMenu().findItem(R.id.nav_btn_lock);
+		if (item != null) item.setVisible(visible);
+	}
+
 	@SuppressWarnings("ConstantConditions")
 	private void showExpiryWarning(ExpiryWarning expiry) {
 		int daysUntilExpiry = getDaysUntilExpiry();
--- a/briar-android/src/main/java/org/briarproject/briar/android/settings/SettingsFragment.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/settings/SettingsFragment.java
@@ -82,10 +82,12 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
 import static org.briarproject.bramble.util.StringUtils.join;
 import static org.briarproject.briar.android.TestingConstants.FEATURE_FLAG_DARK_THEME;
+import static org.briarproject.briar.android.TestingConstants.FEATURE_FLAG_PIN_LOCK;
 import static org.briarproject.briar.android.TestingConstants.FEATURE_FLAG_SIGN_IN_REMINDER;
 import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_RINGTONE;
 import static org.briarproject.briar.android.navdrawer.NavDrawerActivity.INTENT_SIGN_OUT;
+import static org.briarproject.briar.android.util.UiUtils.hasScreenLock;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.BLOG_CHANNEL_ID;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.CONTACT_CHANNEL_ID;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.FORUM_CHANNEL_ID;
@@ -109,6 +111,7 @@ public class SettingsFragment extends PreferenceFragmentCompat
 	public static final String BT_NAMESPACE = BluetoothConstants.ID.getString();
 	public static final String TOR_NAMESPACE = TorConstants.ID.getString();
 	public static final String LANGUAGE = "pref_key_language";
+	public static final String PREF_SCREEN_LOCK = "pref_key_lock";
 	public static final String NOTIFY_SIGN_IN = "pref_key_notify_sign_in";
 	public static final String TOR_LOCATION = "pref_key_tor_location";

@@ -120,13 +123,13 @@ public class SettingsFragment extends PreferenceFragmentCompat
 	private ListPreference enableBluetooth;
 	private ListPreference torNetwork;
 	private SwitchPreference torBlocked;
+	private SwitchPreference screenLock;
 	private SwitchPreference notifyPrivateMessages;
 	private SwitchPreference notifyGroupMessages;
 	private SwitchPreference notifyForumPosts;
 	private SwitchPreference notifyBlogPosts;
 	private SwitchPreference notifyVibration;
 	private SwitchPreference notifyLockscreen;
-
 	private Preference notifySound;

 	// Fields that are accessed from background threads must be volatile
@@ -162,6 +165,7 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		setBlockedCountries();
 		SwitchPreference notifySignIn =
 				(SwitchPreference) findPreference(NOTIFY_SIGN_IN);
+		screenLock = (SwitchPreference) findPreference(PREF_SCREEN_LOCK);
 		notifyPrivateMessages = (SwitchPreference) findPreference(
 				"pref_key_notify_private_messages");
 		notifyGroupMessages = (SwitchPreference) findPreference(
@@ -176,8 +180,6 @@ public class SettingsFragment extends PreferenceFragmentCompat
 				"pref_key_notify_lock_screen");
 		notifySound = findPreference("pref_key_notify_sound");

-		setSettingsEnabled(false);
-
 		language.setOnPreferenceChangeListener(this);
 		theme.setOnPreferenceChangeListener((preference, newValue) -> {
 			if (getActivity() != null) {
@@ -200,6 +202,7 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		enableBluetooth.setOnPreferenceChangeListener(this);
 		torNetwork.setOnPreferenceChangeListener(this);
 		torBlocked.setOnPreferenceChangeListener(this);
+		screenLock.setOnPreferenceChangeListener(this);
 		if (SDK_INT >= 21) {
 			notifyLockscreen.setVisible(true);
 			notifyLockscreen.setOnPreferenceChangeListener(this);
@@ -220,6 +223,7 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		} else {
 			theme.setVisible(FEATURE_FLAG_DARK_THEME);
 			notifySignIn.setVisible(FEATURE_FLAG_SIGN_IN_REMINDER);
+			screenLock.setVisible(FEATURE_FLAG_PIN_LOCK);

 			findPreference("pref_key_explode").setVisible(false);
 			findPreference("pref_key_test_data").setVisible(false);
@@ -229,7 +233,6 @@ public class SettingsFragment extends PreferenceFragmentCompat
 			testing.setVisible(false);
 		}

-		loadSettings();
 	}

 	@Override
@@ -246,6 +249,8 @@ public class SettingsFragment extends PreferenceFragmentCompat
 	public void onStart() {
 		super.onStart();
 		eventBus.addListener(this);
+		setSettingsEnabled(false);
+		loadSettings();
 	}

 	@Override
@@ -354,6 +359,7 @@ public class SettingsFragment extends PreferenceFragmentCompat
 			enableBluetooth.setValue(Boolean.toString(btSetting));
 			torNetwork.setValue(Integer.toString(torNetworkSetting));
 			torBlocked.setChecked(torBlockedSetting);
+			displayScreenLockSetting();

 			if (SDK_INT < 26) {
 				notifyPrivateMessages.setChecked(settings.getBoolean(
@@ -411,9 +417,12 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		// preferences not needed here, because handled by SharedPreferences:
 		// - pref_key_theme
 		// - pref_key_notify_sign_in
+		// preferences partly needed here, because they have their own logic
+		// - pref_key_lock (screenLock -> displayScreenLockSetting())
 		enableBluetooth.setEnabled(enabled);
 		torNetwork.setEnabled(enabled);
 		torBlocked.setEnabled(enabled);
+		if (!enabled) screenLock.setEnabled(false);
 		notifyPrivateMessages.setEnabled(enabled);
 		notifyGroupMessages.setEnabled(enabled);
 		notifyForumPosts.setEnabled(enabled);
@@ -423,6 +432,23 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		notifySound.setEnabled(enabled);
 	}

+	private void displayScreenLockSetting() {
+		if (SDK_INT < 21) {
+			screenLock.setVisible(false);
+		} else {
+			if (getActivity() != null && hasScreenLock(getActivity())) {
+				screenLock.setEnabled(true);
+				screenLock.setChecked(
+						settings.getBoolean(PREF_SCREEN_LOCK, false));
+				screenLock.setSummary(R.string.pref_lock_summary);
+			} else {
+				screenLock.setEnabled(false);
+				screenLock.setChecked(false);
+				screenLock.setSummary(R.string.pref_lock_disabled_summary);
+			}
+		}
+	}
+
 	@TargetApi(26)
 	private void setupNotificationPreference(SwitchPreference pref,
 			String channelId, @StringRes int summary) {
@@ -478,6 +504,10 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		} else if (preference == torBlocked) {
 			boolean torBlockedSetting = (Boolean) newValue;
 			storeTorBlockedSetting(torBlockedSetting);
+		} else if (preference == screenLock) {
+			Settings s = new Settings();
+			s.putBoolean(PREF_SCREEN_LOCK, (Boolean) newValue);
+			storeSettings(s);
 		} else if (preference == notifyPrivateMessages) {
 			Settings s = new Settings();
 			s.putBoolean(PREF_NOTIFY_PRIVATE, (Boolean) newValue);
--- a/briar-android/src/main/java/org/briarproject/briar/android/splash/SplashScreenActivity.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/splash/SplashScreenActivity.java
@@ -14,6 +14,8 @@ import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BaseActivity;
 import org.briarproject.briar.android.login.OpenDatabaseActivity;
 import org.briarproject.briar.android.login.SetupActivity;
+import org.briarproject.briar.android.navdrawer.NavDrawerActivity;
+import org.briarproject.briar.api.android.LockManager;

 import java.util.logging.Logger;

@@ -29,6 +31,8 @@ public class SplashScreenActivity extends BaseActivity {
 	@Inject
 	protected AccountManager accountManager;
 	@Inject
+	protected LockManager lockManager;
+	@Inject
 	protected AndroidExecutor androidExecutor;

 	@Override
@@ -44,7 +48,16 @@ public class SplashScreenActivity extends BaseActivity {
 		setContentView(R.layout.splash);

 		if (accountManager.hasDatabaseKey()) {
-			startActivity(new Intent(this, OpenDatabaseActivity.class));
+			Intent i;
+			if (lockManager.isLocked()) {
+				// The database needs to be opened for the app to be locked.
+				// Start main activity right away. It will open UnlockActivity.
+				// Otherwise, we would end up with two screen unlock inputs.
+				i = new Intent(this, NavDrawerActivity.class);
+			} else {
+				i = new Intent(this, OpenDatabaseActivity.class);
+			}
+			startActivity(i);
 			finish();
 		} else {
 			new Handler().postDelayed(() -> {
--- a/briar-android/src/main/java/org/briarproject/briar/android/util/UiUtils.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/util/UiUtils.java
@@ -2,6 +2,7 @@ package org.briarproject.briar.android.util;

 import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
+import android.app.KeyguardManager;
 import android.content.Context;
 import android.content.DialogInterface.OnClickListener;
 import android.content.Intent;
@@ -36,6 +37,7 @@ import org.briarproject.briar.android.widget.LinkDialogFragment;

 import javax.annotation.Nullable;

+import static android.content.Context.KEYGUARD_SERVICE;
 import static android.content.Context.POWER_SERVICE;
 import static android.content.Intent.CATEGORY_DEFAULT;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
@@ -229,4 +231,15 @@ public class UiUtils {
 		return ContextCompat.getColor(ctx, color);
 	}

+	public static boolean hasScreenLock(Context ctx) {
+		if (SDK_INT < 21) return false;
+		KeyguardManager keyguardManager =
+				(KeyguardManager) ctx.getSystemService(KEYGUARD_SERVICE);
+		if (keyguardManager == null) return false;
+		// check if there's a lock mechanism we can use
+		// first one is true if SIM card is locked, so use second if available
+		return (SDK_INT < 23 && keyguardManager.isKeyguardSecure()) ||
+				(SDK_INT >= 23 && keyguardManager.isDeviceSecure());
+	}
+
 }
--- a/briar-android/src/main/java/org/briarproject/briar/api/android/AndroidNotificationManager.java
+++ b/briar-android/src/main/java/org/briarproject/briar/api/android/AndroidNotificationManager.java
@@ -1,5 +1,7 @@
 package org.briarproject.briar.api.android;

+import android.app.Notification;
+
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.sync.GroupId;

@@ -52,6 +54,10 @@ public interface AndroidNotificationManager {
 	// Actions for pending intents
 	String ACTION_DISMISS_REMINDER = "dismissReminder";

+	Notification getForegroundNotification();
+
+	void updateForegroundNotification(boolean locked);
+
 	void clearContactNotification(ContactId c);

 	void clearAllContactNotifications();
--- a/briar-android/src/main/java/org/briarproject/briar/api/android/LockManager.java
+++ b/briar-android/src/main/java/org/briarproject/briar/api/android/LockManager.java
@@ -0,0 +1,33 @@
+package org.briarproject.briar.api.android;
+
+import android.arch.lifecycle.LiveData;
+import android.support.annotation.UiThread;
+
+public interface LockManager {
+
+	/**
+	 * Returns an observable LiveData to indicate whether the app can be locked.
+	 */
+	LiveData<Boolean> isLockable();
+
+	/**
+	 * Updates the LiveData returned by {@link #isLockable()}.
+	 * It checks whether a device screen lock is available and
+	 * whether the app setting is checked.
+	 */
+	@UiThread
+	void checkIfLockable();
+
+	/**
+	 * Returns true if app is currently locked, false otherwise.
+	 * If the device's screen lock was removed while the app was locked,
+	 * calling this will unlock the app automatically.
+	 */
+	boolean isLocked();
+
+	/**
+	 * Locks the app if true is passed, otherwise unlocks the app.
+	 */
+	void setLocked(boolean locked);
+
+}
--- a/briar-android/src/main/res/layout/activity_unlock.xml
+++ b/briar-android/src/main/res/layout/activity_unlock.xml
@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout
+	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:orientation="vertical"
+	tools:context=".android.login.UnlockActivity">
+
+	<android.support.v7.widget.AppCompatImageView
+		android:id="@+id/image"
+		android:layout_width="150dp"
+		android:layout_height="150dp"
+		android:layout_margin="@dimen/margin_large"
+		android:src="@drawable/splash_screen"
+		app:layout_constraintBottom_toTopOf="@+id/is_locked"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent"
+		app:layout_constraintVertical_chainStyle="spread"
+		app:tint="?attr/colorControlNormal"/>
+
+	<TextView
+		android:id="@+id/is_locked"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_margin="@dimen/margin_large"
+		android:gravity="center"
+		android:text="@string/lock_is_locked"
+		android:textSize="@dimen/text_size_xlarge"
+		app:layout_constraintBottom_toTopOf="@+id/unlock"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/image"
+		app:layout_constraintVertical_chainStyle="spread"/>
+
+	<Button
+		android:id="@+id/unlock"
+		style="@style/BriarButton"
+		android:layout_width="match_parent"
+		android:layout_height="wrap_content"
+		android:layout_margin="@dimen/margin_large"
+		android:text="@string/lock_unlock"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"/>
+
+</android.support.constraint.ConstraintLayout>
--- a/briar-android/src/main/res/menu/navigation_drawer.xml
+++ b/briar-android/src/main/res/menu/navigation_drawer.xml
@@ -26,6 +26,11 @@
 			android:id="@+id/nav_btn_settings"
 			android:icon="@drawable/ic_settings_black_24dp"
 			android:title="@string/settings_button"/>
+		<item
+			android:id="@+id/nav_btn_lock"
+			android:icon="@drawable/startup_lock"
+			android:title="@string/lock_button"
+			android:visible="false"/>
 		<item
 			android:id="@+id/nav_btn_signout"
 			android:icon="@drawable/ic_signout"
--- a/briar-android/src/main/res/values-ast/strings.xml
+++ b/briar-android/src/main/res/values-ast/strings.xml
@@ -133,7 +133,7 @@
  <string name="security_settings_title">Seguridá</string>
  <string name="panic_setting">Configuración del Botón d\'espantu</string>
  <string name="panic_setting_title">Botón d\'espantu</string>
-  <string name="lock_setting_title">Colar</string>
+  <string name="panic_setting_signout_title">Colar</string>
  <string name="uninstall_setting_title">Desinstalar Briar</string>
  <!--Settings Notifications-->
  <string name="notification_settings_title">Avisos</string>
--- a/briar-android/src/main/res/values-bg/strings.xml
+++ b/briar-android/src/main/res/values-bg/strings.xml
@@ -271,8 +271,8 @@
  <string name="panic_app_setting_none">Няма</string>
  <string name="dialog_title_connect_panic_app">Потвърждение на паник приложение</string>
  <string name="dialog_message_connect_panic_app">Сигурни ли сте, че искате да позволите на %1$s да задейства унищожителни действия на паник бутон?</string>
-  <string name="lock_setting_title">Отписване</string>
-  <string name="lock_setting_summary">Отписване от Briar, ако паник бутонът е натиснат</string>
+  <string name="panic_setting_signout_title">Отписване</string>
+  <string name="panic_setting_signout_summary">Отписване от Briar, ако паник бутонът е натиснат</string>
  <string name="purge_setting_title">Изтриване на профил</string>
  <string name="purge_setting_summary">Изтриване на Briar профила, ако паник бутонът е натиснат. Внимание: Изтрива завинаги вашия профил, контакти и съобщения</string>
  <string name="uninstall_setting_title">Деинсталиране на Briar</string>
--- a/briar-android/src/main/res/values-br/strings.xml
+++ b/briar-android/src/main/res/values-br/strings.xml
@@ -164,7 +164,7 @@
  <string name="change_password">Cheñch ar ger-tremen</string>
  <string name="confirm_new_password">Kadarnaat ar ger-tremen nevez</string>
  <string name="panic_app_setting_none">Hini ebet</string>
-  <string name="lock_setting_title">Digevreañ</string>
+  <string name="panic_setting_signout_title">Digevreañ</string>
  <!--Settings Notifications-->
  <string name="notify_sound_setting_disabled">Hini ebet</string>
  <!--Settings Feedback-->
--- a/briar-android/src/main/res/values-ca/strings.xml
+++ b/briar-android/src/main/res/values-ca/strings.xml
@@ -343,8 +343,8 @@
  <string name="panic_app_setting_none">Cap</string>
  <string name="dialog_title_connect_panic_app">Confirmeu l\'aplicació de pànic</string>
  <string name="dialog_message_connect_panic_app">Segur que voleu permetre que %1$s desencadeni accions destructives a conseqüència del botó de pànic?</string>
-  <string name="lock_setting_title">Tanca la sessió</string>
-  <string name="lock_setting_summary">Tanca la sessió de Briar si es prem un botó de pànic</string>
+  <string name="panic_setting_signout_title">Tanca la sessió</string>
+  <string name="panic_setting_signout_summary">Tanca la sessió de Briar si es prem un botó de pànic</string>
  <string name="purge_setting_title">Esborreu el compte</string>
  <string name="purge_setting_summary">Suprimeix el compte de Briar si es prem el botó de pànic. Atenció: En aquest cas, s\'eliminarien permanentment les vostres identitats, contactes i missatges</string>
  <string name="uninstall_setting_title">Desinstal·leu Briar</string>
--- a/briar-android/src/main/res/values-cs/strings.xml
+++ b/briar-android/src/main/res/values-cs/strings.xml
@@ -346,8 +346,8 @@
  <string name="panic_app_setting_none">Žádný</string>
  <string name="dialog_title_connect_panic_app">Potvrdit aplikaci Paniky</string>
  <string name="dialog_message_connect_panic_app">Jste si jisti, že chcete povolit %1$s spustit akci zneškodnění pomocí tlačítka paniky?</string>
-  <string name="lock_setting_title">Odhlásit se</string>
-  <string name="lock_setting_summary">Odhlásit se z Briar, pokud je stisknuto tlačítko paniky</string>
+  <string name="panic_setting_signout_title">Odhlásit se</string>
+  <string name="panic_setting_signout_summary">Odhlásit se z Briar, pokud je stisknuto tlačítko paniky</string>
  <string name="purge_setting_title">Odstranit účet</string>
  <string name="purge_setting_summary">Vymazat váš Briar účet pokud je stlačeno tlačítko paniky. Upozornění: Toto trvale vymaže vaši identitu, kontakty a zprávy</string>
  <string name="uninstall_setting_title">Odinstalovat Briar</string>
--- a/briar-android/src/main/res/values-de/strings.xml
+++ b/briar-android/src/main/res/values-de/strings.xml
@@ -333,8 +333,8 @@
  <string name="panic_app_setting_none">Keine</string>
  <string name="dialog_title_connect_panic_app">Bestätige Panik-App</string>
  <string name="dialog_message_connect_panic_app">Bist du sicher, dass du %1$s erlauben willst, Panik-Button-Ereignisse auszulösen? Dies kann zum Löschen von Daten führen.</string>
-  <string name="lock_setting_title">Abmelden</string>
-  <string name="lock_setting_summary">Von Briar abmelden, wenn ein Panik-Button aktiviert wird</string>
+  <string name="panic_setting_signout_title">Abmelden</string>
+  <string name="panic_setting_signout_summary">Von Briar abmelden, wenn ein Panik-Button aktiviert wird</string>
  <string name="purge_setting_title">Konto löschen</string>
  <string name="purge_setting_summary">Briar-Konto löschen, wenn der Panik-Button gedrückt wird. Achtung: Es werden alle Identitäten, Kontakte und Nachrichten unwiderruflich gelöscht.</string>
  <string name="uninstall_setting_title">Briar deinstallieren</string>
--- a/briar-android/src/main/res/values-es/strings.xml
+++ b/briar-android/src/main/res/values-es/strings.xml
@@ -327,8 +327,8 @@
  <string name="panic_app_setting_none">Ninguna</string>
  <string name="dialog_title_connect_panic_app">Confirmar aplicación de pánico</string>
  <string name="dialog_message_connect_panic_app">¿Seguro que quieres permitir que %1$s lance acciones destructivas de botón de pánico?</string>
-  <string name="lock_setting_title">Cerrar sesión</string>
-  <string name="lock_setting_summary">Cerrar la sesión de Briar si se pulsa un botón de pánico</string>
+  <string name="panic_setting_signout_title">Cerrar sesión</string>
+  <string name="panic_setting_signout_summary">Cerrar la sesión de Briar si se pulsa un botón de pánico</string>
  <string name="purge_setting_title">Eliminar cuenta</string>
  <string name="purge_setting_summary">Eliminar tu cuenta de Briar si se pulsa un botón de pánico. Advertencia: esto eliminará permanentemente tus identidades, contactos y mensajes</string>
  <string name="uninstall_setting_title">Desinstalar Briar</string>
--- a/briar-android/src/main/res/values-eu/strings.xml
+++ b/briar-android/src/main/res/values-eu/strings.xml
@@ -343,8 +343,8 @@
  <string name="panic_app_setting_none">Bat ere ez</string>
  <string name="dialog_title_connect_panic_app">Berretsi larrialdi-aplikazioa</string>
  <string name="dialog_message_connect_panic_app">Ziur %1$s baimendu nahi duzula larrialdi botoiaren ekintza suntsitzaileak burutzea?</string>
-  <string name="lock_setting_title">Amaitu saioa</string>
-  <string name="lock_setting_summary">Amaitu saioa larrialdi botoia zapaltzen bada</string>
+  <string name="panic_setting_signout_title">Amaitu saioa</string>
+  <string name="panic_setting_signout_summary">Amaitu saioa larrialdi botoia zapaltzen bada</string>
  <string name="purge_setting_title">Ezabatu kontua</string>
  <string name="purge_setting_summary">Ezabatu kontua Briar larrialdi botoia zapaltzen bada. Kontuz: Honek behin betiko ezabatuko ditu zure identitateak, kontaktuak eta mezuak</string>
  <string name="uninstall_setting_title">Desinstalatu Briar</string>
--- a/briar-android/src/main/res/values-fa/strings.xml
+++ b/briar-android/src/main/res/values-fa/strings.xml
@@ -382,8 +382,8 @@
  <string name="panic_app_setting_none">هیچکدام</string>
  <string name="dialog_title_connect_panic_app">تایید برنامه هراس</string>
  <string name="dialog_message_connect_panic_app">آیا مطمئن هستید که میخواهید به %1$s اجازه دهید تا باعث عملیات مخرب دکمه هراس بشود؟</string>
-  <string name="lock_setting_title">خروج</string>
-  <string name="lock_setting_summary">در صورت کلیک بر روی کلید هراس از برایر خارج شو</string>
+  <string name="panic_setting_signout_title">خروج</string>
+  <string name="panic_setting_signout_summary">در صورت کلیک بر روی کلید هراس از برایر خارج شو</string>
  <string name="purge_setting_title">حذف حساب کاربری</string>
  <string name="purge_setting_summary">پاک کردن حساب کاربری برایر شما در صورتی که دکمه هراس فشار داده شود. اخطار: این باعث پاک شدن دائمی تمام هویت ها، مخاطبان و پیام های شما خواهد شد</string>
  <string name="uninstall_setting_title">پاک کردن برایر</string>
--- a/briar-android/src/main/res/values-fi/strings.xml
+++ b/briar-android/src/main/res/values-fi/strings.xml
@@ -343,8 +343,8 @@
  <string name="panic_app_setting_none">Ei mitään</string>
  <string name="dialog_title_connect_panic_app">Vahvista paniikkisovellus</string>
  <string name="dialog_message_connect_panic_app">Oletko varma, että haluat myöntää ohjelmalle %1$s luvan laukaista tuhoa aiheuttavia paniikkinapin toimintoja?</string>
-  <string name="lock_setting_title">Kirjaudu ulos</string>
-  <string name="lock_setting_summary">Kirjaudu ulos Briarista jos paniikkinappia on painettu</string>
+  <string name="panic_setting_signout_title">Kirjaudu ulos</string>
+  <string name="panic_setting_signout_summary">Kirjaudu ulos Briarista jos paniikkinappia on painettu</string>
  <string name="purge_setting_title">Poista tili</string>
  <string name="purge_setting_summary">Poista Briar tilisi jos paniikkinappia on painettu. Varoitus: Tämä tulee pysyvästi poistamaan sinun tunnukset, yhteystiedot ja viestit</string>
  <string name="uninstall_setting_title">Poista Briarin asennus</string>
--- a/briar-android/src/main/res/values-fr/strings.xml
+++ b/briar-android/src/main/res/values-fr/strings.xml
@@ -343,8 +343,8 @@
  <string name="panic_app_setting_none">Aucune</string>
  <string name="dialog_title_connect_panic_app">Confirmer l’application d’urgence</string>
  <string name="dialog_message_connect_panic_app">Voulez-vous vraiment autoriser %1$s à déclencher les actions destructrices du bouton d’urgence ?</string>
-  <string name="lock_setting_title">Déconnexion</string>
-  <string name="lock_setting_summary">Se déconnecter de Briar lorsqu’on appuie sur un bouton d’urgence</string>
+  <string name="panic_setting_signout_title">Déconnexion</string>
+  <string name="panic_setting_signout_summary">Se déconnecter de Briar lorsqu’on appuie sur un bouton d’urgence</string>
  <string name="purge_setting_title">Supprimer le compte</string>
  <string name="purge_setting_summary">Supprimer votre compte Briar lorsqu’on appuie sur un bouton d’urgence. Attention : cela supprimera définitivement vos identités, contacts et messages</string>
  <string name="uninstall_setting_title">Désinstaller Briar</string>
--- a/briar-android/src/main/res/values-gl/strings.xml
+++ b/briar-android/src/main/res/values-gl/strings.xml
@@ -341,8 +341,8 @@
  <string name="panic_app_setting_none">Ningún</string>
  <string name="dialog_title_connect_panic_app">Confirme a App do pánico</string>
  <string name="dialog_message_connect_panic_app">Está segura de querer permitir a %1$s activar accións destrutivas do botón do pánico?</string>
-  <string name="lock_setting_title">Finalizar sesión</string>
-  <string name="lock_setting_summary">Desconecte de Briar si o botón do pánico se preme</string>
+  <string name="panic_setting_signout_title">Finalizar sesión</string>
+  <string name="panic_setting_signout_summary">Desconecte de Briar si o botón do pánico se preme</string>
  <string name="purge_setting_title">Eliminar conta</string>
  <string name="purge_setting_summary">Elimina a súa conta en Briar si se preme o botón do pánico. Coidado: Esto eliminará permanentemente as súas identidade, contactos e mensaxes</string>
  <string name="uninstall_setting_title">Desinstalar Briar</string>
--- a/briar-android/src/main/res/values-he/strings.xml
+++ b/briar-android/src/main/res/values-he/strings.xml
@@ -239,7 +239,7 @@
  <string name="security_settings_title">אבטחה</string>
  <string name="choose_new_password">סיסמא חדשה</string>
  <string name="panic_app_setting_none">כלום</string>
-  <string name="lock_setting_title">יציאה</string>
+  <string name="panic_setting_signout_title">יציאה</string>
  <string name="purge_setting_title">מחק חשבון</string>
  <!--Settings Notifications-->
  <string name="notification_settings_title">הודעות מערכת</string>
--- a/briar-android/src/main/res/values-hi/strings.xml
+++ b/briar-android/src/main/res/values-hi/strings.xml
@@ -327,8 +327,8 @@
  <string name="panic_app_setting_none">कुछ भी नहीं</string>
  <string name="dialog_title_connect_panic_app">आतंक ऐप की पुष्टि करें</string>
  <string name="dialog_message_connect_panic_app">क्या आप निश्चित हैं कि आप%1$s को विनाशकारी आतंक बटन क्रियाओं को ट्रिगर करने की अनुमति देना चाहते हैं?</string>
-  <string name="lock_setting_title">साइन आउट</string>
-  <string name="lock_setting_summary">यदि कोई आतंक बटन दबाया जाता है तो बियर से साइन आउट करें</string>
+  <string name="panic_setting_signout_title">साइन आउट</string>
+  <string name="panic_setting_signout_summary">यदि कोई आतंक बटन दबाया जाता है तो बियर से साइन आउट करें</string>
  <string name="purge_setting_title">खाता हटा दो</string>
  <string name="purge_setting_summary">यदि आपका आतंक बटन दबाया गया हो तो अपने ब्रियर खाते को हटा दें। सावधानी: यह आपकी पहचान, संपर्क और संदेश को स्थायी रूप से हटा देगा</string>
  <string name="uninstall_setting_title">बरिअर की स्थापना रद्द करें</string>
--- a/briar-android/src/main/res/values-it/strings.xml
+++ b/briar-android/src/main/res/values-it/strings.xml
@@ -343,8 +343,8 @@
  <string name="panic_app_setting_none">Nessuno</string>
  <string name="dialog_title_connect_panic_app">Conferma App Panico</string>
  <string name="dialog_message_connect_panic_app">Sei sicuro di voler consentire %1$s di attivare le azioni distruttive del pulsante panico?</string>
-  <string name="lock_setting_title">Esci</string>
-  <string name="lock_setting_summary">Uscire da Briar se viene premuto un pulsante di panico</string>
+  <string name="panic_setting_signout_title">Esci</string>
+  <string name="panic_setting_signout_summary">Uscire da Briar se viene premuto un pulsante di panico</string>
  <string name="purge_setting_title">Elimina Account</string>
  <string name="purge_setting_summary">Cancella il tuo account Briar se un panic button è premuto. Attenzione: ciò cancellerà permanentemente le tue identità, contatti e messaggi</string>
  <string name="uninstall_setting_title">Disinstalla Briar</string>
--- a/briar-android/src/main/res/values-ja/strings.xml
+++ b/briar-android/src/main/res/values-ja/strings.xml
@@ -114,7 +114,7 @@
  <string name="change_password">パスワードの変更</string>
  <string name="confirm_new_password">新しいパスワードの確認</string>
  <string name="panic_app_setting_none">なし</string>
-  <string name="lock_setting_title">サインアウト</string>
+  <string name="panic_setting_signout_title">サインアウト</string>
  <string name="purge_setting_title">アカウントを削除</string>
  <!--Settings Notifications-->
  <string name="notification_settings_title">通知</string>
--- a/briar-android/src/main/res/values-nb/strings.xml
+++ b/briar-android/src/main/res/values-nb/strings.xml
@@ -296,8 +296,8 @@
  <string name="panic_app_setting_none">Inget</string>
  <string name="dialog_title_connect_panic_app">Bekreft panikk-knapp-program</string>
  <string name="dialog_message_connect_panic_app">Er du sikker på at du vil tillate %1$s å utløse destruktive panikk-knapp-handlinger?</string>
-  <string name="lock_setting_title">Logg ut</string>
-  <string name="lock_setting_summary">Logg ut av Briar hvis panikk-knappen trykkes</string>
+  <string name="panic_setting_signout_title">Logg ut</string>
+  <string name="panic_setting_signout_summary">Logg ut av Briar hvis panikk-knappen trykkes</string>
  <string name="purge_setting_title">Slett konto</string>
  <string name="purge_setting_summary">Slett Briar-kontoen din hvis panikk-knappen trykkes. Advarsel: Dette vil slette dine identiteter, kontakter og meldinger for godt.</string>
  <string name="uninstall_setting_title">Avinstaller Briar</string>
--- a/briar-android/src/main/res/values-nl/strings.xml
+++ b/briar-android/src/main/res/values-nl/strings.xml
@@ -343,8 +343,8 @@
  <string name="panic_app_setting_none">Geen</string>
  <string name="dialog_title_connect_panic_app">Bevestig paniekapp</string>
  <string name="dialog_message_connect_panic_app">Weet je zeker dat je wil toestaan dat %1$s destructieve paniekknopacties mag veroorzaken?</string>
-  <string name="lock_setting_title">Log uit</string>
-  <string name="lock_setting_summary">Log uit op Briar als de paniekknop wordt ingedrukt.</string>
+  <string name="panic_setting_signout_title">Log uit</string>
+  <string name="panic_setting_signout_summary">Log uit op Briar als de paniekknop wordt ingedrukt.</string>
  <string name="purge_setting_title">Verwijder account</string>
  <string name="purge_setting_summary">Verwijder je Briar-account als een paniekknop wordt ingedrukt. Let op: Dit zal permanent je identiteit, contacten en berichten verwijderen.</string>
  <string name="uninstall_setting_title">Deïnstalleer Briar</string>
--- a/briar-android/src/main/res/values-oc/strings.xml
+++ b/briar-android/src/main/res/values-oc/strings.xml
@@ -309,8 +309,8 @@ Volètz suprimir vòstre compte e ne crear un nòu ?\n
  <string name="panic_app_setting_none">Cap</string>
  <string name="dialog_title_connect_panic_app">Confirmar l’aplicacion Urgéncia</string>
  <string name="dialog_message_connect_panic_app">Sètz segur de voler autorizar %1$s a aviar las accions de destruccion del boton Urgéncia ?</string>
-  <string name="lock_setting_title">Se desconnectar</string>
-  <string name="lock_setting_summary">Se desconnectar de Briar en apiejant lo boton Urgéncia ?</string>
+  <string name="panic_setting_signout_title">Se desconnectar</string>
+  <string name="panic_setting_signout_summary">Se desconnectar de Briar en apiejant lo boton Urgéncia ?</string>
  <string name="purge_setting_title">Suprimir lo compte</string>
  <string name="purge_setting_summary">Suprimir vòstre compte en apiejant lo boton Urgéncia. Mèfi, aquò escafarà per totjorn vòstra identitat, vòstres contactes e messatges.</string>
  <string name="uninstall_setting_title">Desinstallar Briar</string>
--- a/briar-android/src/main/res/values-pl/strings.xml
+++ b/briar-android/src/main/res/values-pl/strings.xml
@@ -361,8 +361,8 @@
  <string name="panic_app_setting_none">Brak</string>
  <string name="dialog_title_connect_panic_app">Potwierdź Awaryjną Aplikację</string>
  <string name="dialog_message_connect_panic_app">Czy na pewno chcesz pozwolić %1$s aby działała jako przycisk wyjścia awaryjnego?</string>
-  <string name="lock_setting_title">Wyloguj się</string>
-  <string name="lock_setting_summary">Wyloguj się z Briar jeśli przycisk zostanie wciśnięty</string>
+  <string name="panic_setting_signout_title">Wyloguj się</string>
+  <string name="panic_setting_signout_summary">Wyloguj się z Briar jeśli przycisk zostanie wciśnięty</string>
  <string name="purge_setting_title">Skasuj Konto</string>
  <string name="purge_setting_summary">Skasuj Twoje konto Briar jeśli przycisk wyjścia awaryjnego zostanie wciśnięty. Ostrzeżenie: Ta akcja usunie permanentnie Twoje konto, kontakty i wiadomości</string>
  <string name="uninstall_setting_title">Odinstaluj Briar</string>
--- a/briar-android/src/main/res/values-pt-rBR/strings.xml
+++ b/briar-android/src/main/res/values-pt-rBR/strings.xml
@@ -332,8 +332,8 @@
  <string name="panic_app_setting_none">Nenhum</string>
  <string name="dialog_title_connect_panic_app">Confirmar aplicativo de pânico</string>
  <string name="dialog_message_connect_panic_app">Você tem certeza que quer permitir que %1$s ative ações destrutivas do botão de pânico?</string>
-  <string name="lock_setting_title">Desconectar</string>
-  <string name="lock_setting_summary">Desconectar do Briar se o botão de pânico for apertado</string>
+  <string name="panic_setting_signout_title">Desconectar</string>
+  <string name="panic_setting_signout_summary">Desconectar do Briar se o botão de pânico for apertado</string>
  <string name="purge_setting_title">Apagar conta</string>
  <string name="purge_setting_summary">Apagar sua conta do Briar se o botão de pânico for apertado. Atenção: isso irá apagar permanentemente suas identidades, contatos e mensagens</string>
  <string name="uninstall_setting_title">Desinstalar o Briar</string>
--- a/briar-android/src/main/res/values-ro/strings.xml
+++ b/briar-android/src/main/res/values-ro/strings.xml
@@ -354,8 +354,8 @@
  <string name="panic_app_setting_none">Nici una</string>
  <string name="dialog_title_connect_panic_app">Confirmare aplicație de panică</string>
  <string name="dialog_message_connect_panic_app">Sigur doriți să permiteți %1$s să declanșeze acțiuni destructive pentru butonul de panică?</string>
-  <string name="lock_setting_title">Ieșire</string>
-  <string name="lock_setting_summary">Ieși din Briar dacă un buton de panică este apăsat</string>
+  <string name="panic_setting_signout_title">Ieșire</string>
+  <string name="panic_setting_signout_summary">Ieși din Briar dacă un buton de panică este apăsat</string>
  <string name="purge_setting_title">Șterge cont</string>
  <string name="purge_setting_summary">Ștergeți contul Briar dacă este apăsat buton de panică. Atenție: aceasta va șterge definitiv identitatea, contactele și mesajele dvs.</string>
  <string name="uninstall_setting_title">Dezinstalare Briar</string>
--- a/briar-android/src/main/res/values-ru/strings.xml
+++ b/briar-android/src/main/res/values-ru/strings.xml
@@ -363,8 +363,8 @@
  <string name="panic_app_setting_none">Нет</string>
  <string name="dialog_title_connect_panic_app">Подтвердить приложение тревожной кнопки</string>
  <string name="dialog_message_connect_panic_app">Вы уверены, что хотите разрешить %1$s запускать действия тревожной кнопки?</string>
-  <string name="lock_setting_title">Выйти</string>
-  <string name="lock_setting_summary">Выйти из Briar, если нажата тревожная кнопка</string>
+  <string name="panic_setting_signout_title">Выйти</string>
+  <string name="panic_setting_signout_summary">Выйти из Briar, если нажата тревожная кнопка</string>
  <string name="purge_setting_title">Удалить аккаунт</string>
  <string name="purge_setting_summary">Удалить вашу учетную запись Briar при нажатии тревожной кнопки. Внимание: это необратимо удалит ваши идентификаторы, контакты и сообщения</string>
  <string name="uninstall_setting_title">Удалить Briar</string>
--- a/briar-android/src/main/res/values-sq/strings.xml
+++ b/briar-android/src/main/res/values-sq/strings.xml
@@ -343,8 +343,8 @@
  <string name="panic_app_setting_none">Asnjë</string>
  <string name="dialog_title_connect_panic_app">Ripohoni Aplikacion Paniku</string>
  <string name="dialog_message_connect_panic_app">Jeni i sigurt se doni të lejohet %1$s të prodhojë veprime shkatërruese butoni paniku?</string>
-  <string name="lock_setting_title">Dilni</string>
-  <string name="lock_setting_summary">Dil nga Briar-i nëse shtypet një buton paniku</string>
+  <string name="panic_setting_signout_title">Dilni</string>
+  <string name="panic_setting_signout_summary">Dil nga Briar-i nëse shtypet një buton paniku</string>
  <string name="purge_setting_title">Fshi Llogarinë</string>
  <string name="purge_setting_summary">Fshijeni llogarinë tuaj Briar, nëse shtypet një buton paniku. Kujdes: Kjo do të shkaktojë fshirjen e identiteteve, kontakteve dhe mesazheve tuaj</string>
  <string name="uninstall_setting_title">Çinstalo Briar-in</string>
--- a/briar-android/src/main/res/values-sr/strings.xml
+++ b/briar-android/src/main/res/values-sr/strings.xml
@@ -237,8 +237,8 @@
  <string name="panic_app_setting_none">Ništa</string>
  <string name="dialog_title_connect_panic_app">Potvrdi Panic App</string>
  <string name="dialog_message_connect_panic_app">Jeste li sigurni da želite da dozvolite %1$s da pokrene destruktivne akcije panik dugmeta?</string>
-  <string name="lock_setting_title">Izlogujte se</string>
-  <string name="lock_setting_summary">Izloguj se iz Briar-a ako je pritisnuto panik dugme</string>
+  <string name="panic_setting_signout_title">Izlogujte se</string>
+  <string name="panic_setting_signout_summary">Izloguj se iz Briar-a ako je pritisnuto panik dugme</string>
  <string name="purge_setting_title">Izbriši račun</string>
  <string name="purge_setting_summary">Izbriši Briar račun ako je panik dugme pritisnuto. Pažnja: Ovo će permanentno izbrisati vaše identitete, kontakte i poruke</string>
  <string name="uninstall_setting_title">Deinstaliraj Briar</string>
--- a/briar-android/src/main/res/values-sv/strings.xml
+++ b/briar-android/src/main/res/values-sv/strings.xml
@@ -129,8 +129,8 @@
  <string name="choose_new_password">Nytt lösenord</string>
  <string name="confirm_new_password">Bekräfta nytt lösenord</string>
  <string name="panic_app_setting_none">Ingen</string>
-  <string name="lock_setting_title">Logga ut</string>
-  <string name="lock_setting_summary">Logga ut från Briar om panikknappen tryckts</string>
+  <string name="panic_setting_signout_title">Logga ut</string>
+  <string name="panic_setting_signout_summary">Logga ut från Briar om panikknappen tryckts</string>
  <string name="purge_setting_title">Radera kontot</string>
  <string name="uninstall_setting_title">Avinstallera Briar</string>
  <!--Settings Notifications-->
--- a/briar-android/src/main/res/values-tr/strings.xml
+++ b/briar-android/src/main/res/values-tr/strings.xml
@@ -264,8 +264,8 @@
  <string name="panic_app_setting_none">Yok</string>
  <string name="dialog_title_connect_panic_app">Panik Uygulaması Doğrulama</string>
  <string name="dialog_message_connect_panic_app">%1$s kişisinin yıkıcı panik düğmesi eylemlerini tetiklemesine izin vermek istediğinizden emin misiniz?</string>
-  <string name="lock_setting_title">Çıkış Yap</string>
-  <string name="lock_setting_summary">Panik Butonuna basıldığında Briar\'dan çıkış yap</string>
+  <string name="panic_setting_signout_title">Çıkış Yap</string>
+  <string name="panic_setting_signout_summary">Panik Butonuna basıldığında Briar\'dan çıkış yap</string>
  <string name="purge_setting_title">Hesabı Sil</string>
  <string name="purge_setting_summary">Bir panik düğmesine basıldığında Briar hesabınızı silin. Dikkat: Bu, kimliklerinizi, kayıtlarınızı ve iletilerinizi kalıcı olarak silecektir.</string>
  <string name="uninstall_setting_title">Briar\'ı Kaldır</string>
--- a/briar-android/src/main/res/values-zh-rCN/strings.xml
+++ b/briar-android/src/main/res/values-zh-rCN/strings.xml
@@ -333,8 +333,8 @@
  <string name="panic_app_setting_none">无</string>
  <string name="dialog_title_connect_panic_app">确认应急应用</string>
  <string name="dialog_message_connect_panic_app">是否允许 %1$s 触发破坏性应急开关反应？</string>
-  <string name="lock_setting_title">登出</string>
-  <string name="lock_setting_summary">触发应急开关时登出 Briar</string>
+  <string name="panic_setting_signout_title">登出</string>
+  <string name="panic_setting_signout_summary">触发应急开关时登出 Briar</string>
  <string name="purge_setting_title">删除账号</string>
  <string name="purge_setting_summary">触发应急开关时删除您的账号。注意：您的身份、联系人和消息将会永久遗失。</string>
  <string name="uninstall_setting_title">卸载 Briar</string>
--- a/briar-android/src/main/res/values/strings.xml
+++ b/briar-android/src/main/res/values/strings.xml
@@ -62,6 +62,7 @@
 	<string name="groups_button">Private Groups</string>
 	<string name="forums_button">Forums</string>
 	<string name="blogs_button">Blogs</string>
+	<string name="lock_button">Lock App</string>
 	<string name="settings_button">Settings</string>
 	<string name="sign_out_button">Sign Out</string>

@@ -356,6 +357,9 @@

 	<!-- Settings Security and Panic -->
 	<string name="security_settings_title">Security</string>
+	<string name="pref_lock_title">Screen Lock</string>
+	<string name="pref_lock_summary">Use the device\'s screen lock to protect Briar while signed in</string>
+	<string name="pref_lock_disabled_summary">Set up a screen lock for your device to protect Briar while signed in</string>
 	<string name="change_password">Change password</string>
 	<string name="current_password">Current password</string>
 	<string name="choose_new_password">New password</string>
@@ -370,8 +374,8 @@
 	<string name="panic_app_setting_none">None</string>
 	<string name="dialog_title_connect_panic_app">Confirm Panic App</string>
 	<string name="dialog_message_connect_panic_app">Are you sure that you want to allow %1$s to trigger destructive panic button actions?</string>
-	<string name="lock_setting_title">Sign Out</string>
-	<string name="lock_setting_summary">Sign out of Briar if a panic button is pressed</string>
+	<string name="panic_setting_signout_title">Sign Out</string>
+	<string name="panic_setting_signout_summary">Sign out of Briar if a panic button is pressed</string>
 	<string name="purge_setting_title">Delete Account</string>
 	<string name="purge_setting_summary">Delete your Briar account if a panic button is pressed. Caution: This will permanently delete your identities, contacts and messages</string>
 	<string name="uninstall_setting_title">Uninstall Briar</string>
@@ -444,4 +448,11 @@
 	<string name="permission_camera_denied_toast">Camera permission was not granted</string>
 	<string name="qr_code">QR code</string>
 	<string name="show_qr_code_fullscreen">Show QR code fullscreen</string>
+
+	<!-- App Locking -->
+	<string name="lock_unlock">Unlock Briar</string>
+	<string name="lock_unlock_verbose">Enter your device PIN, pattern or password to unlock Briar</string>
+	<string name="lock_is_locked">Briar is locked</string>
+	<string name="lock_tap_to_unlock">Tap to unlock</string>
+
 </resources>
--- a/briar-android/src/main/res/xml/panic_preferences.xml
+++ b/briar-android/src/main/res/xml/panic_preferences.xml
@@ -12,8 +12,8 @@
 		android:defaultValue="true"
 		android:enabled="false"
 		android:key="pref_key_lock"
-		android:summary="@string/lock_setting_summary"
-		android:title="@string/lock_setting_title"/>
+		android:summary="@string/panic_setting_signout_summary"
+		android:title="@string/panic_setting_signout_title"/>

 	<SwitchPreference
 		android:defaultValue="false"
--- a/briar-android/src/main/res/xml/settings.xml
+++ b/briar-android/src/main/res/xml/settings.xml
@@ -56,6 +56,13 @@
 		android:layout="@layout/preferences_category"
 		android:title="@string/security_settings_title">

+		<CheckBoxPreference
+			android:key="pref_key_lock"
+			android:persistent="false"
+			android:summary="@string/pref_lock_summary"
+			android:title="@string/pref_lock_title"
+			android:enabled="false"/>
+
 		<Preference
 			android:key="pref_key_change_password"
 			android:title="@string/change_password">