Use FLAG_SECURE for sensitive screens such as encrypted chat rooms

app/src/main/java/org/linphone/activities/main/about/AboutFragment.kt

@@ -25,12 +25,12 @@ import android.os.Bundle
 import androidx.lifecycle.ViewModelProvider
 import androidx.navigation.fragment.findNavController
 import org.linphone.R
-import org.linphone.activities.GenericFragment
 import org.linphone.activities.main.MainActivity
+import org.linphone.activities.main.fragments.SecureFragment
 import org.linphone.databinding.AboutFragmentBinding
 import org.linphone.utils.AppUtils
 
-class AboutFragment : GenericFragment<AboutFragmentBinding>() {
+class AboutFragment : SecureFragment<AboutFragmentBinding>() {
     private lateinit var viewModel: AboutViewModel
 
     override fun getLayoutId(): Int = R.layout.about_fragment

app/src/main/java/org/linphone/activities/main/chat/fragments/ChatRoomCreationFragment.kt

@@ -26,15 +26,15 @@ import androidx.navigation.fragment.findNavController
 import androidx.recyclerview.widget.DividerItemDecoration
 import androidx.recyclerview.widget.LinearLayoutManager
 import org.linphone.R
-import org.linphone.activities.GenericFragment
 import org.linphone.activities.main.MainActivity
 import org.linphone.activities.main.chat.adapters.ChatRoomCreationContactsAdapter
 import org.linphone.activities.main.chat.viewmodels.ChatRoomCreationViewModel
+import org.linphone.activities.main.fragments.SecureFragment
 import org.linphone.activities.main.viewmodels.SharedMainViewModel
 import org.linphone.core.Address
 import org.linphone.databinding.ChatRoomCreationFragmentBinding
 
-class ChatRoomCreationFragment : GenericFragment<ChatRoomCreationFragmentBinding>() {
+class ChatRoomCreationFragment : SecureFragment<ChatRoomCreationFragmentBinding>() {
     private lateinit var viewModel: ChatRoomCreationViewModel
     private lateinit var sharedViewModel: SharedMainViewModel
     private lateinit var adapter: ChatRoomCreationContactsAdapter

app/src/main/java/org/linphone/activities/main/chat/fragments/DetailChatRoomFragment.kt

@@ -95,6 +95,7 @@ class DetailChatRoomFragment : MasterFragment<ChatRoomDetailFragmentBinding, Cha
         val chatRoom = sharedViewModel.selectedChatRoom.value
         chatRoom ?: return
         chatRoomAddress = chatRoom.peerAddress.asStringUriOnly()
+        isSecure = chatRoom.currentParams.encryptionEnabled()
 
         viewModel = ViewModelProvider(
             this,

app/src/main/java/org/linphone/activities/main/chat/fragments/DevicesFragment.kt

@@ -23,13 +23,13 @@ import android.os.Bundle
 import androidx.lifecycle.ViewModelProvider
 import androidx.navigation.fragment.findNavController
 import org.linphone.R
-import org.linphone.activities.GenericFragment
 import org.linphone.activities.main.chat.viewmodels.DevicesListViewModel
 import org.linphone.activities.main.chat.viewmodels.DevicesListViewModelFactory
+import org.linphone.activities.main.fragments.SecureFragment
 import org.linphone.activities.main.viewmodels.SharedMainViewModel
 import org.linphone.databinding.ChatRoomDevicesFragmentBinding
 
-class DevicesFragment : GenericFragment<ChatRoomDevicesFragmentBinding>() {
+class DevicesFragment : SecureFragment<ChatRoomDevicesFragmentBinding>() {
     private lateinit var listViewModel: DevicesListViewModel
     private lateinit var sharedViewModel: SharedMainViewModel
 
@@ -47,6 +47,8 @@ class DevicesFragment : GenericFragment<ChatRoomDevicesFragmentBinding>() {
         val chatRoom = sharedViewModel.selectedChatRoom.value
         chatRoom ?: return
 
+        isSecure = chatRoom.currentParams.encryptionEnabled()
+
         listViewModel = ViewModelProvider(
             this,
             DevicesListViewModelFactory(chatRoom)

app/src/main/java/org/linphone/activities/main/chat/fragments/EphemeralFragment.kt

@@ -23,13 +23,13 @@ import android.os.Bundle
 import androidx.lifecycle.ViewModelProvider
 import androidx.navigation.fragment.findNavController
 import org.linphone.R
-import org.linphone.activities.GenericFragment
 import org.linphone.activities.main.chat.viewmodels.EphemeralViewModel
 import org.linphone.activities.main.chat.viewmodels.EphemeralViewModelFactory
+import org.linphone.activities.main.fragments.SecureFragment
 import org.linphone.activities.main.viewmodels.SharedMainViewModel
 import org.linphone.databinding.ChatRoomEphemeralFragmentBinding
 
-class EphemeralFragment : GenericFragment<ChatRoomEphemeralFragmentBinding>() {
+class EphemeralFragment : SecureFragment<ChatRoomEphemeralFragmentBinding>() {
     private lateinit var viewModel: EphemeralViewModel
     private lateinit var sharedViewModel: SharedMainViewModel
 
@@ -40,6 +40,7 @@ class EphemeralFragment : GenericFragment<ChatRoomEphemeralFragmentBinding>() {
     override fun onActivityCreated(savedInstanceState: Bundle?) {
         super.onActivityCreated(savedInstanceState)
 
+        isSecure = true
         binding.lifecycleOwner = this
 
         sharedViewModel = activity?.run {

app/src/main/java/org/linphone/activities/main/chat/fragments/GroupInfoFragment.kt

@@ -26,12 +26,12 @@ import androidx.navigation.fragment.findNavController
 import androidx.recyclerview.widget.DividerItemDecoration
 import androidx.recyclerview.widget.LinearLayoutManager
 import org.linphone.R
-import org.linphone.activities.GenericFragment
 import org.linphone.activities.main.MainActivity
 import org.linphone.activities.main.chat.GroupChatRoomMember
 import org.linphone.activities.main.chat.adapters.GroupInfoParticipantsAdapter
 import org.linphone.activities.main.chat.viewmodels.GroupInfoViewModel
 import org.linphone.activities.main.chat.viewmodels.GroupInfoViewModelFactory
+import org.linphone.activities.main.fragments.SecureFragment
 import org.linphone.activities.main.viewmodels.DialogViewModel
 import org.linphone.activities.main.viewmodels.SharedMainViewModel
 import org.linphone.core.Address
@@ -40,7 +40,7 @@ import org.linphone.core.ChatRoomCapabilities
 import org.linphone.databinding.ChatRoomGroupInfoFragmentBinding
 import org.linphone.utils.DialogUtils
 
-class GroupInfoFragment : GenericFragment<ChatRoomGroupInfoFragmentBinding>() {
+class GroupInfoFragment : SecureFragment<ChatRoomGroupInfoFragmentBinding>() {
     private lateinit var viewModel: GroupInfoViewModel
     private lateinit var sharedViewModel: SharedMainViewModel
     private lateinit var adapter: GroupInfoParticipantsAdapter
@@ -58,6 +58,7 @@ class GroupInfoFragment : GenericFragment<ChatRoomGroupInfoFragmentBinding>() {
         } ?: throw Exception("Invalid Activity")
 
         val chatRoom: ChatRoom? = sharedViewModel.selectedGroupChatRoom.value
+        isSecure = chatRoom?.currentParams?.encryptionEnabled() ?: false
 
         viewModel = ViewModelProvider(
             this,

app/src/main/java/org/linphone/activities/main/chat/fragments/ImdnFragment.kt

@@ -25,16 +25,16 @@ import androidx.navigation.fragment.findNavController
 import androidx.recyclerview.widget.DividerItemDecoration
 import androidx.recyclerview.widget.LinearLayoutManager
 import org.linphone.R
-import org.linphone.activities.GenericFragment
 import org.linphone.activities.main.chat.adapters.ImdnAdapter
 import org.linphone.activities.main.chat.viewmodels.ImdnViewModel
 import org.linphone.activities.main.chat.viewmodels.ImdnViewModelFactory
+import org.linphone.activities.main.fragments.SecureFragment
 import org.linphone.activities.main.viewmodels.SharedMainViewModel
 import org.linphone.core.tools.Log
 import org.linphone.databinding.ChatRoomImdnFragmentBinding
 import org.linphone.utils.RecyclerViewHeaderDecoration
 
-class ImdnFragment : GenericFragment<ChatRoomImdnFragmentBinding>() {
+class ImdnFragment : SecureFragment<ChatRoomImdnFragmentBinding>() {
     private lateinit var viewModel: ImdnViewModel
     private lateinit var adapter: ImdnAdapter
     private lateinit var sharedViewModel: SharedMainViewModel
@@ -55,6 +55,8 @@ class ImdnFragment : GenericFragment<ChatRoomImdnFragmentBinding>() {
         val chatRoom = sharedViewModel.selectedChatRoom.value
         chatRoom ?: return
 
+        isSecure = chatRoom.currentParams.encryptionEnabled()
+
         if (arguments != null) {
             val messageId = arguments?.getString("MessageId")
             val message = if (messageId != null) chatRoom.findMessage(messageId) else null

app/src/main/java/org/linphone/activities/main/chat/fragments/MasterChatRoomsFragment.kt

@@ -71,6 +71,7 @@ class MasterChatRoomsFragment : MasterFragment<ChatRoomMasterFragmentBinding, Ch
     override fun onActivityCreated(savedInstanceState: Bundle?) {
         super.onActivityCreated(savedInstanceState)
 
+        isSecure = true
         binding.lifecycleOwner = this
 
         listViewModel = ViewModelProvider(this).get(ChatRoomsListViewModel::class.java)

app/src/main/java/org/linphone/activities/main/dialer/fragments/DialerFragment.kt

@@ -33,9 +33,9 @@ import org.linphone.BuildConfig
 import org.linphone.LinphoneApplication.Companion.coreContext
 import org.linphone.LinphoneApplication.Companion.corePreferences
 import org.linphone.R
-import org.linphone.activities.GenericFragment
 import org.linphone.activities.main.MainActivity
 import org.linphone.activities.main.dialer.viewmodels.DialerViewModel
+import org.linphone.activities.main.fragments.SecureFragment
 import org.linphone.activities.main.viewmodels.DialogViewModel
 import org.linphone.activities.main.viewmodels.SharedMainViewModel
 import org.linphone.core.tools.Log
@@ -43,7 +43,7 @@ import org.linphone.databinding.DialerFragmentBinding
 import org.linphone.utils.AppUtils
 import org.linphone.utils.DialogUtils
 
-class DialerFragment : GenericFragment<DialerFragmentBinding>() {
+class DialerFragment : SecureFragment<DialerFragmentBinding>() {
     private lateinit var viewModel: DialerViewModel
     private lateinit var sharedViewModel: SharedMainViewModel
 

app/src/main/java/org/linphone/activities/main/fragments/MasterFragment.kt

@@ -24,7 +24,6 @@ import android.os.Bundle
 import androidx.databinding.ViewDataBinding
 import androidx.lifecycle.ViewModelProvider
 import org.linphone.R
-import org.linphone.activities.GenericFragment
 import org.linphone.activities.main.viewmodels.DialogViewModel
 import org.linphone.activities.main.viewmodels.ListTopBarViewModel
 import org.linphone.utils.AppUtils
@@ -35,7 +34,7 @@ import org.linphone.utils.SelectionListAdapter
  * This fragment can be inherited by all fragments that will display a list
  * where items can be selected for removal through the ListTopBarFragment
  */
-abstract class MasterFragment<T : ViewDataBinding, U : SelectionListAdapter<*, *>> : GenericFragment<T>() {
+abstract class MasterFragment<T : ViewDataBinding, U : SelectionListAdapter<*, *>> : SecureFragment<T>() {
     protected var _adapter: U? = null
     protected val adapter get() = _adapter!!
 

app/src/main/java/org/linphone/activities/main/fragments/SecureFragment.kt

@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2010-2020 Belledonne Communications SARL.
+ *
+ * This file is part of linphone-android
+ * (see https://www.linphone.org).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.linphone.activities.main.fragments
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.view.WindowManager
+import androidx.core.view.ViewCompat
+import androidx.databinding.ViewDataBinding
+import androidx.lifecycle.lifecycleScope
+import java.util.*
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import org.linphone.activities.GenericFragment
+import org.linphone.core.tools.Log
+
+abstract class SecureFragment<T : ViewDataBinding> : GenericFragment<T>() {
+    protected var isSecure: Boolean = false
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        // Assume we might want to be secure to prevent quick visible blink while screen recording.
+        enableSecureMode(true)
+        return super.onCreateView(inflater, container, savedInstanceState)
+    }
+
+    override fun onResume() {
+        if (isSecure) {
+            enableSecureMode(isSecure)
+        } else {
+            // This is a workaround to prevent a small blink showing the previous secured screen
+            lifecycleScope.launch {
+                withContext(Dispatchers.Main) {
+                    delay(200)
+                    enableSecureMode(isSecure)
+                }
+            }
+        }
+        super.onResume()
+    }
+
+    private fun enableSecureMode(enable: Boolean) {
+        Log.d("[Secure Fragment] ${if (enable) "Enabling" else "Disabling"} secure flag on window")
+        val window = requireActivity().window
+        val windowManager = requireActivity().windowManager
+
+        val flags: Int = window.attributes.flags
+        if ((enable && flags and WindowManager.LayoutParams.FLAG_SECURE != 0) ||
+            (!enable && flags and WindowManager.LayoutParams.FLAG_SECURE == 0)) {
+            Log.d("[Secure Fragment] Secure flag is already ${if (enable) "enabled" else "disabled"}, skipping...")
+            return
+        }
+
+        if (enable) {
+            window.addFlags(WindowManager.LayoutParams.FLAG_SECURE)
+        } else {
+            window.clearFlags(WindowManager.LayoutParams.FLAG_SECURE)
+        }
+
+        if (ViewCompat.isAttachedToWindow(window.decorView)) {
+            Log.d("[Secure Fragment] Redrawing window decorView to apply flag")
+            windowManager.updateViewLayout(window.decorView, window.attributes)
+        }
+    }
+}

app/src/main/java/org/linphone/activities/main/settings/fragments/SettingsFragment.kt

@@ -23,8 +23,8 @@ import android.os.Bundle
 import androidx.lifecycle.ViewModelProvider
 import androidx.navigation.fragment.findNavController
 import org.linphone.R
-import org.linphone.activities.GenericFragment
 import org.linphone.activities.main.*
+import org.linphone.activities.main.fragments.SecureFragment
 import org.linphone.activities.main.navigateToAccountSettings
 import org.linphone.activities.main.navigateToAudioSettings
 import org.linphone.activities.main.navigateToTunnelSettings
@@ -34,7 +34,7 @@ import org.linphone.activities.main.viewmodels.SharedMainViewModel
 import org.linphone.core.tools.Log
 import org.linphone.databinding.SettingsFragmentBinding
 
-class SettingsFragment : GenericFragment<SettingsFragmentBinding>() {
+class SettingsFragment : SecureFragment<SettingsFragmentBinding>() {
     private lateinit var sharedViewModel: SharedMainViewModel
     private lateinit var viewModel: SettingsViewModel
 

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

@@ -1,6 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    android:orientation="vertical" android:layout_width="match_parent"
+    android:orientation="vertical"
-    android:layout_height="match_parent">
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="?attr/backgroundColor">
 
 </LinearLayout>