diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index e8fe0ed5dd..20d17bc892 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -105,6 +105,11 @@
             android:screenOrientation="portrait"
             android:windowSoftInputMode="adjustResize"
             android:theme="@style/Theme.Session.DayNight.FlatActionBar" />
+        <activity
+            android:name="org.thoughtcrime.securesms.loki.activities.BackupRestoreActivity"
+            android:screenOrientation="portrait"
+            android:windowSoftInputMode="adjustResize"
+            android:theme="@style/Theme.Session.DayNight.FlatActionBar" />
         <activity
             android:name="org.thoughtcrime.securesms.loki.activities.LinkDeviceActivity"
             android:screenOrientation="portrait"
diff --git a/build.gradle b/build.gradle
index 5b96847b45..c000f41ea8 100644
--- a/build.gradle
+++ b/build.gradle
@@ -89,9 +89,12 @@ dependencies {
     implementation 'androidx.multidex:multidex:2.0.1'
     implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
     implementation 'androidx.lifecycle:lifecycle-common-java8:2.2.0'
+    implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0'
     implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.2.0'
-    implementation "androidx.work:work-runtime-ktx:2.4.0"
+    implementation 'androidx.activity:activity-ktx:1.1.0'
+    implementation 'androidx.fragment:fragment-ktx:1.3.0-beta01'
     implementation "androidx.core:core-ktx:1.3.2"
+    implementation "androidx.work:work-runtime-ktx:2.4.0"
 
     implementation ("com.google.firebase:firebase-messaging:18.0.0") {
         exclude group: 'com.google.firebase', module: 'firebase-core'
@@ -364,6 +367,19 @@ android {
             includeAndroidResources = true
         }
     }
+
+    buildFeatures {
+        dataBinding true
+    }
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
 }
 
 /*
diff --git a/res/layout-sw400dp/activity_landing.xml b/res/layout-sw400dp/activity_landing.xml
index 7ecae1b271..606789cf76 100644
--- a/res/layout-sw400dp/activity_landing.xml
+++ b/res/layout-sw400dp/activity_landing.xml
@@ -49,6 +49,16 @@
         android:layout_marginRight="@dimen/massive_spacing"
         android:text="@string/activity_landing_restore_button_title" />
 
+    <Button
+        style="@style/Widget.Session.Button.Common.ProminentOutline"
+        android:id="@+id/restoreBackupButton"
+        android:layout_width="match_parent"
+        android:layout_height="@dimen/medium_button_height"
+        android:layout_marginLeft="@dimen/massive_spacing"
+        android:layout_marginTop="@dimen/medium_spacing"
+        android:layout_marginRight="@dimen/massive_spacing"
+        android:text="@string/activity_landing_restore_backup_button_title" />
+
     <Button
         android:id="@+id/linkButton"
         android:layout_width="match_parent"
diff --git a/res/layout/activity_backup_restore.xml b/res/layout/activity_backup_restore.xml
new file mode 100644
index 0000000000..365ff39cd1
--- /dev/null
+++ b/res/layout/activity_backup_restore.xml
@@ -0,0 +1,124 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<layout 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">
+    <data>
+        <import type="org.thoughtcrime.securesms.loki.activities.BackupRestoreViewModel"/>
+        <import type="org.thoughtcrime.securesms.util.BackupUtil"/>
+        <import type="android.view.View"/>
+        <variable
+            name="viewModel"
+            type="org.thoughtcrime.securesms.loki.activities.BackupRestoreViewModel" />
+    </data>
+
+    <FrameLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:orientation="vertical">
+
+            <View
+                android:layout_width="match_parent"
+                android:layout_height="0dp"
+                android:layout_weight="1" />
+
+            <TextView
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginLeft="@dimen/very_large_spacing"
+                android:layout_marginRight="@dimen/very_large_spacing"
+                android:text="@string/activity_backup_restore_title"
+                android:textColor="@color/text"
+                android:textSize="@dimen/large_font_size"
+                android:textStyle="bold" />
+
+            <TextView
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginLeft="@dimen/very_large_spacing"
+                android:layout_marginTop="4dp"
+                android:layout_marginRight="@dimen/very_large_spacing"
+                android:text="@string/activity_backup_restore_explanation_1"
+                android:textColor="@color/text"
+                android:textSize="@dimen/small_font_size" />
+
+            <Button
+                android:id="@+id/buttonSelectFile"
+                style="@style/Button.Primary"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginLeft="@dimen/very_large_spacing"
+                android:layout_marginTop="4dp"
+                android:layout_marginRight="@dimen/very_large_spacing"
+                android:textColor="@color/black"
+                android:text="@{viewModel.backupFile != null ? BackupRestoreViewModel.uriToFileName(buttonSelectFile, viewModel.backupFile) : @string/activity_backup_restore_select_file}"
+                tools:text="Select a file"
+                />
+
+            <EditText
+                android:id="@+id/backupCode"
+                style="@style/SmallSessionEditText"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginLeft="@dimen/very_large_spacing"
+                android:layout_marginTop="10dp"
+                android:layout_marginRight="@dimen/very_large_spacing"
+                android:hint="@string/activity_backup_restore_passphrase"
+                android:inputType="numberDecimal|textNoSuggestions"
+                android:digits="0123456789"
+                android:maxLength="@{BackupUtil.BACKUP_PASSPHRASE_LENGTH}"
+                android:text="@={viewModel.backupPassphrase}"
+                android:visibility="@{viewModel.backupFile != null ? View.VISIBLE : View.INVISIBLE}"/>
+
+            <View
+                android:layout_width="match_parent"
+                android:layout_height="0dp"
+                android:layout_weight="1" />
+
+            <Button
+                android:id="@+id/restoreButton"
+                style="@style/Widget.Session.Button.Common.ProminentFilled"
+                android:layout_width="match_parent"
+                android:layout_height="@dimen/medium_button_height"
+                android:layout_marginLeft="@dimen/massive_spacing"
+                android:layout_marginRight="@dimen/massive_spacing"
+                android:text="@string/continue_2"
+                android:visibility="@{BackupRestoreViewModel.validateData(viewModel.backupFile, viewModel.backupPassphrase) ? View.VISIBLE : View.INVISIBLE}"/>
+
+            <TextView
+                android:id="@+id/termsTextView"
+                android:layout_width="match_parent"
+                android:layout_height="@dimen/onboarding_button_bottom_offset"
+                android:layout_marginLeft="@dimen/massive_spacing"
+                android:layout_marginRight="@dimen/massive_spacing"
+                android:gravity="center"
+                android:text="By using this service, you agree to our Terms of Service and Privacy Policy"
+                android:textColor="@color/text"
+                android:textColorLink="@color/text"
+                android:textSize="@dimen/very_small_font_size" /> <!-- Intentionally not yet translated -->
+
+        </LinearLayout>
+
+        <FrameLayout
+            android:id="@+id/busyIndicator"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:background="#A4000000"
+            android:visibility="@{viewModel.processingBackupFile == true ? View.VISIBLE : View.GONE}"
+            tools:visibility="visible">
+
+            <ProgressBar
+                android:layout_width="64dp"
+                android:layout_height="64dp"
+                android:indeterminate="true"
+                android:layout_gravity="center"/>
+
+        </FrameLayout>
+
+    </FrameLayout>
+
+</layout>
\ No newline at end of file
diff --git a/res/layout/activity_landing.xml b/res/layout/activity_landing.xml
index 7dbddf0219..3b38247f19 100644
--- a/res/layout/activity_landing.xml
+++ b/res/layout/activity_landing.xml
@@ -49,6 +49,16 @@
         android:layout_marginRight="@dimen/massive_spacing"
         android:text="@string/activity_landing_restore_button_title" />
 
+    <Button
+        style="@style/Widget.Session.Button.Common.ProminentOutline"
+        android:id="@+id/restoreBackupButton"
+        android:layout_width="match_parent"
+        android:layout_height="@dimen/medium_button_height"
+        android:layout_marginLeft="@dimen/massive_spacing"
+        android:layout_marginTop="@dimen/small_spacing"
+        android:layout_marginRight="@dimen/massive_spacing"
+        android:text="@string/activity_landing_restore_backup_button_title" />
+
     <Button
         android:id="@+id/linkButton"
         android:layout_width="match_parent"
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 24a69f92e8..df0d4b07f3 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -1545,6 +1545,7 @@
     <string name="RegistrationLockDialog_disable_registration_lock_pin">Disable Registration Lock PIN?</string>
     <string name="RegistrationLockDialog_disable">Disable</string>
     <string name="preferences_chats__backups">Backups</string>
+    <string name="preferences_chats__backup_export_error">An error occurred during exporting a backup. Please try again later.</string>
     <string name="prompt_passphrase_activity__signal_is_locked">Session is Locked</string>
     <string name="prompt_passphrase_activity__tap_to_unlock">TAP TO UNLOCK</string>
     <string name="RegistrationLockDialog_reminder">Reminder:</string>
@@ -1669,6 +1670,7 @@
     <string name="activity_landing_title_2">Your Session begins here...</string>
     <string name="activity_landing_register_button_title">Create Session ID</string>
     <string name="activity_landing_restore_button_title">Continue Your Session</string>
+    <string name="activity_landing_restore_backup_button_title">Restore Backup</string>
     <string name="activity_landing_link_button_title">Link to an existing account</string>
     <string name="activity_landing_device_unlinked_dialog_title">Your device was unlinked successfully</string>
 
@@ -1868,4 +1870,9 @@
 
     <string name="dialog_backup_activation_failed">Failed to activate backups. Please try again or contact support.</string>
 
+    <string name="activity_backup_restore_title">Restore backup</string>
+    <string name="activity_backup_restore_select_file">Select a file</string>
+    <string name="activity_backup_restore_explanation_1">Select a backup file and enter the passphrase it was created with.</string>
+    <string name="activity_backup_restore_passphrase">30-digit passphrase</string>
+
 </resources>
diff --git a/res/xml/preferences_chats.xml b/res/xml/preferences_chats.xml
index 4b1d69e8f0..abbd24ea72 100644
--- a/res/xml/preferences_chats.xml
+++ b/res/xml/preferences_chats.xml
@@ -94,7 +94,7 @@
 
         <org.thoughtcrime.securesms.components.SwitchPreferenceCompat
             android:defaultValue="false"
-            android:key="pref_backup_enabled_v2"
+            android:key="pref_backup_enabled_v3"
             android:title="@string/preferences_chats__chat_backups"
             android:summary="@string/preferences_chats__backup_chats_to_external_storage" />
 
@@ -102,7 +102,7 @@
             android:key="pref_backup_create"
             android:title="@string/preferences_chats__create_backup"
             android:persistent="false"
-            android:dependency="pref_backup_enabled_v2"
+            android:dependency="pref_backup_enabled_v3"
             tools:summary="Last backup: 3 days ago" />
 
     </PreferenceCategory>
diff --git a/src/org/thoughtcrime/securesms/ApplicationContext.java b/src/org/thoughtcrime/securesms/ApplicationContext.java
index 7d136bd6a6..884d5c4208 100644
--- a/src/org/thoughtcrime/securesms/ApplicationContext.java
+++ b/src/org/thoughtcrime/securesms/ApplicationContext.java
@@ -66,6 +66,7 @@ import org.thoughtcrime.securesms.loki.api.BackgroundPollWorker;
 import org.thoughtcrime.securesms.loki.api.ClosedGroupPoller;
 import org.thoughtcrime.securesms.loki.api.LokiPushNotificationManager;
 import org.thoughtcrime.securesms.loki.api.PublicChatManager;
+import org.thoughtcrime.securesms.loki.api.ResetThreadSessionJob;
 import org.thoughtcrime.securesms.loki.database.LokiAPIDatabase;
 import org.thoughtcrime.securesms.loki.database.LokiThreadDatabase;
 import org.thoughtcrime.securesms.loki.database.LokiUserDatabase;
diff --git a/src/org/thoughtcrime/securesms/RegistrationActivity.java b/src/org/thoughtcrime/securesms/RegistrationActivity.java
index 42307afe83..18f6d7eb4d 100644
--- a/src/org/thoughtcrime/securesms/RegistrationActivity.java
+++ b/src/org/thoughtcrime/securesms/RegistrationActivity.java
@@ -5,6 +5,7 @@ import android.animation.Animator;
 import android.annotation.SuppressLint;
 import android.content.Context;
 import android.content.Intent;
+import android.net.Uri;
 import android.os.AsyncTask;
 import android.os.Bundle;
 import androidx.annotation.NonNull;
@@ -34,7 +35,7 @@ import org.greenrobot.eventbus.EventBus;
 import org.greenrobot.eventbus.Subscribe;
 import org.greenrobot.eventbus.ThreadMode;
 import org.thoughtcrime.securesms.animation.AnimationCompleteListener;
-import org.thoughtcrime.securesms.backup.FullBackupBase;
+import org.thoughtcrime.securesms.backup.BackupEvent;
 import org.thoughtcrime.securesms.backup.FullBackupImporter;
 import org.thoughtcrime.securesms.components.LabeledEditText;
 import org.thoughtcrime.securesms.components.registration.CallMeCountDownView;
@@ -326,9 +327,9 @@ public class RegistrationActivity extends BaseActionBarActivity implements Verif
                 Context        context  = RegistrationActivity.this;
                 SQLiteDatabase database = DatabaseFactory.getBackupDatabase(context);
 
-                FullBackupImporter.importFile(context,
-                                              AttachmentSecretProvider.getInstance(context).getOrCreateAttachmentSecret(),
-                                              database, backup.getFile(), passphrase);
+                FullBackupImporter.importFromUri(context,
+                        AttachmentSecretProvider.getInstance(context).getOrCreateAttachmentSecret(),
+                        database, Uri.fromFile(backup.getFile()), passphrase);
 
                 DatabaseFactory.upgradeRestored(context, database);
                 NotificationChannels.restoreContactNotificationChannels(context);
@@ -871,7 +872,7 @@ public class RegistrationActivity extends BaseActionBarActivity implements Verif
   }
 
   @Subscribe(threadMode = ThreadMode.MAIN)
-  public void onEvent(FullBackupBase.BackupEvent event) {
+  public void onEvent(BackupEvent event) {
     if (event.getCount() == 0) restoreBackupProgress.setText(R.string.RegistrationActivity_checking);
     else                       restoreBackupProgress.setText(getString(R.string.RegistrationActivity_d_messages_so_far, event.getCount()));
   }
diff --git a/src/org/thoughtcrime/securesms/backup/BackupDialog.java b/src/org/thoughtcrime/securesms/backup/BackupDialog.java
index 177e75e1dd..ee49138201 100644
--- a/src/org/thoughtcrime/securesms/backup/BackupDialog.java
+++ b/src/org/thoughtcrime/securesms/backup/BackupDialog.java
@@ -30,7 +30,7 @@ public class BackupDialog {
           @NonNull BackupDirSelector backupDirSelector) {
 
     String[] password   = BackupUtil.generateBackupPassphrase();
-    String   passwordSt = Util.join(password, " ");
+    String   passwordSt = Util.join(password, "");
 
     AlertDialog dialog = new AlertDialog.Builder(context)
                                           .setTitle(R.string.BackupDialog_enable_local_backups)
@@ -82,7 +82,7 @@ public class BackupDialog {
 
     dialog.findViewById(R.id.number_table).setOnClickListener(v -> {
       ((ClipboardManager)context.getSystemService(Context.CLIPBOARD_SERVICE)).setPrimaryClip(ClipData.newPlainText("text", passwordSt));
-      Toast.makeText(context, R.string.BackupDialog_copied_to_clipboard, Toast.LENGTH_LONG).show();
+      Toast.makeText(context, R.string.BackupDialog_copied_to_clipboard, Toast.LENGTH_SHORT).show();
     });
 
 
diff --git a/src/org/thoughtcrime/securesms/backup/BackupEvent.kt b/src/org/thoughtcrime/securesms/backup/BackupEvent.kt
new file mode 100644
index 0000000000..614dc30bba
--- /dev/null
+++ b/src/org/thoughtcrime/securesms/backup/BackupEvent.kt
@@ -0,0 +1,14 @@
+package org.thoughtcrime.securesms.backup
+
+data class BackupEvent constructor(val type: Type, val count: Int, val exception: Exception?) {
+
+    enum class Type {
+        PROGRESS, FINISHED
+    }
+
+    companion object {
+        @JvmStatic fun createProgress(count: Int) = BackupEvent(Type.PROGRESS, count, null)
+        @JvmStatic fun createFinished() = BackupEvent(Type.FINISHED, 0, null)
+        @JvmStatic fun createFinished(e: Exception?) = BackupEvent(Type.FINISHED, 0, e)
+    }
+}
\ No newline at end of file
diff --git a/src/org/thoughtcrime/securesms/backup/FullBackupBase.java b/src/org/thoughtcrime/securesms/backup/FullBackupBase.java
deleted file mode 100644
index c88c4fec21..0000000000
--- a/src/org/thoughtcrime/securesms/backup/FullBackupBase.java
+++ /dev/null
@@ -1,65 +0,0 @@
-package org.thoughtcrime.securesms.backup;
-
-
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-
-import org.greenrobot.eventbus.EventBus;
-import org.whispersystems.libsignal.util.ByteUtil;
-
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
-
-public abstract class FullBackupBase {
-
-  @SuppressWarnings("unused")
-  private static final String TAG = FullBackupBase.class.getSimpleName();
-
-  static class BackupStream {
-    static @NonNull byte[] getBackupKey(@NonNull String passphrase, @Nullable byte[] salt) {
-      try {
-        EventBus.getDefault().post(new BackupEvent(BackupEvent.Type.PROGRESS, 0));
-
-        MessageDigest digest = MessageDigest.getInstance("SHA-512");
-        byte[]        input  = passphrase.replace(" ", "").getBytes();
-        byte[]        hash   = input;
-
-        if (salt != null) digest.update(salt);
-
-        for (int i=0;i<250000;i++) {
-          if (i % 1000 == 0) EventBus.getDefault().post(new BackupEvent(BackupEvent.Type.PROGRESS, 0));
-          digest.update(hash);
-          hash = digest.digest(input);
-        }
-
-        return ByteUtil.trim(hash, 32);
-      } catch (NoSuchAlgorithmException e) {
-        throw new AssertionError(e);
-      }
-    }
-  }
-
-  public static class BackupEvent {
-    public enum Type {
-      PROGRESS,
-      FINISHED
-    }
-
-    private final Type type;
-    private final int count;
-
-    BackupEvent(Type type, int count) {
-      this.type  = type;
-      this.count = count;
-    }
-
-    public Type getType() {
-      return type;
-    }
-
-    public int getCount() {
-      return count;
-    }
-  }
-
-}
diff --git a/src/org/thoughtcrime/securesms/backup/FullBackupExporter.java b/src/org/thoughtcrime/securesms/backup/FullBackupExporter.java
deleted file mode 100644
index a7f1fb1582..0000000000
--- a/src/org/thoughtcrime/securesms/backup/FullBackupExporter.java
+++ /dev/null
@@ -1,429 +0,0 @@
-package org.thoughtcrime.securesms.backup;
-
-import android.content.Context;
-import android.database.Cursor;
-import android.net.Uri;
-import android.text.TextUtils;
-
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-
-import com.annimon.stream.function.Consumer;
-import com.annimon.stream.function.Predicate;
-import com.google.protobuf.ByteString;
-
-import net.sqlcipher.database.SQLiteDatabase;
-
-import org.greenrobot.eventbus.EventBus;
-import org.thoughtcrime.securesms.attachments.AttachmentId;
-import org.thoughtcrime.securesms.crypto.AttachmentSecret;
-import org.thoughtcrime.securesms.crypto.ClassicDecryptingPartInputStream;
-import org.thoughtcrime.securesms.crypto.IdentityKeyUtil;
-import org.thoughtcrime.securesms.crypto.ModernDecryptingPartInputStream;
-import org.thoughtcrime.securesms.database.AttachmentDatabase;
-import org.thoughtcrime.securesms.database.GroupReceiptDatabase;
-import org.thoughtcrime.securesms.database.MmsDatabase;
-import org.thoughtcrime.securesms.database.MmsSmsColumns;
-import org.thoughtcrime.securesms.database.OneTimePreKeyDatabase;
-import org.thoughtcrime.securesms.database.SearchDatabase;
-import org.thoughtcrime.securesms.database.SessionDatabase;
-import org.thoughtcrime.securesms.database.SignedPreKeyDatabase;
-import org.thoughtcrime.securesms.database.SmsDatabase;
-import org.thoughtcrime.securesms.database.StickerDatabase;
-import org.thoughtcrime.securesms.logging.Log;
-import org.thoughtcrime.securesms.profiles.AvatarHelper;
-import org.thoughtcrime.securesms.util.Conversions;
-import org.thoughtcrime.securesms.util.Util;
-import org.whispersystems.libsignal.kdf.HKDFv3;
-import org.whispersystems.libsignal.util.ByteUtil;
-
-import java.io.Closeable;
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.Flushable;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
-import java.security.InvalidAlgorithmParameterException;
-import java.security.InvalidKeyException;
-import java.security.NoSuchAlgorithmException;
-import java.util.LinkedList;
-import java.util.List;
-
-import javax.crypto.BadPaddingException;
-import javax.crypto.Cipher;
-import javax.crypto.IllegalBlockSizeException;
-import javax.crypto.Mac;
-import javax.crypto.NoSuchPaddingException;
-import javax.crypto.spec.IvParameterSpec;
-import javax.crypto.spec.SecretKeySpec;
-
-public class FullBackupExporter extends FullBackupBase {
-
-  @SuppressWarnings("unused")
-  private static final String TAG = FullBackupExporter.class.getSimpleName();
-
-  public static void export(@NonNull Context context,
-                            @NonNull AttachmentSecret attachmentSecret,
-                            @NonNull SQLiteDatabase input,
-                            @NonNull Uri fileUri,
-                            @NonNull String passphrase)
-      throws IOException
-  {
-    OutputStream baseOutputStream = context.getContentResolver().openOutputStream(fileUri);
-    if (baseOutputStream == null) {
-      throw new IOException("Cannot open an output stream for the file URI: " + fileUri.toString());
-    }
-
-    try (BackupFrameOutputStream outputStream = new BackupFrameOutputStream(baseOutputStream, passphrase)) {
-      outputStream.writeDatabaseVersion(input.getVersion());
-
-      List<String> tables = exportSchema(input, outputStream);
-      int          count  = 0;
-
-      for (String table : tables) {
-        if (table.equals(SmsDatabase.TABLE_NAME) || table.equals(MmsDatabase.TABLE_NAME)) {
-          count = exportTable(table, input, outputStream, cursor -> cursor.getInt(cursor.getColumnIndexOrThrow(MmsSmsColumns.EXPIRES_IN)) <= 0, null, count);
-        } else if (table.equals(GroupReceiptDatabase.TABLE_NAME)) {
-          count = exportTable(table, input, outputStream, cursor -> isForNonExpiringMessage(input, cursor.getLong(cursor.getColumnIndexOrThrow(GroupReceiptDatabase.MMS_ID))), null, count);
-        } else if (table.equals(AttachmentDatabase.TABLE_NAME)) {
-          count = exportTable(table, input, outputStream, cursor -> isForNonExpiringMessage(input, cursor.getLong(cursor.getColumnIndexOrThrow(AttachmentDatabase.MMS_ID))), cursor -> exportAttachment(attachmentSecret, cursor, outputStream), count);
-        } else if (table.equals(StickerDatabase.TABLE_NAME)) {
-          count = exportTable(table, input, outputStream, cursor -> true, cursor -> exportSticker(attachmentSecret, cursor, outputStream), count);
-        } else if (!table.equals(SignedPreKeyDatabase.TABLE_NAME)       &&
-                   !table.equals(OneTimePreKeyDatabase.TABLE_NAME)      &&
-                   !table.equals(SessionDatabase.TABLE_NAME)            &&
-                   !table.startsWith(SearchDatabase.SMS_FTS_TABLE_NAME) &&
-                   !table.startsWith(SearchDatabase.MMS_FTS_TABLE_NAME) &&
-                   !table.startsWith("sqlite_"))
-        {
-          count = exportTable(table, input, outputStream, null, null, count);
-        }
-      }
-
-      for (BackupProtos.SharedPreference preference : IdentityKeyUtil.getBackupRecord(context)) {
-        EventBus.getDefault().post(new BackupEvent(BackupEvent.Type.PROGRESS, ++count));
-        outputStream.write(preference);
-      }
-
-      for (File avatar : AvatarHelper.getAvatarFiles(context)) {
-        EventBus.getDefault().post(new BackupEvent(BackupEvent.Type.PROGRESS, ++count));
-        outputStream.write(avatar.getName(), new FileInputStream(avatar), avatar.length());
-      }
-
-      outputStream.writeEnd();
-      EventBus.getDefault().post(new BackupEvent(BackupEvent.Type.FINISHED, ++count));
-    }
-  }
-
-  private static List<String> exportSchema(@NonNull SQLiteDatabase input, @NonNull BackupFrameOutputStream outputStream)
-      throws IOException
-  {
-    List<String> tables = new LinkedList<>();
-
-    try (Cursor cursor = input.rawQuery("SELECT sql, name, type FROM sqlite_master", null)) {
-      while (cursor != null && cursor.moveToNext()) {
-        String sql  = cursor.getString(0);
-        String name = cursor.getString(1);
-        String type = cursor.getString(2);
-
-        if (sql != null) {
-
-          boolean isSmsFtsSecretTable = name != null && !name.equals(SearchDatabase.SMS_FTS_TABLE_NAME) && name.startsWith(SearchDatabase.SMS_FTS_TABLE_NAME);
-          boolean isMmsFtsSecretTable = name != null && !name.equals(SearchDatabase.MMS_FTS_TABLE_NAME) && name.startsWith(SearchDatabase.MMS_FTS_TABLE_NAME);
-
-          if (!isSmsFtsSecretTable && !isMmsFtsSecretTable) {
-            if ("table".equals(type)) {
-              tables.add(name);
-            }
-
-            outputStream.write(BackupProtos.SqlStatement.newBuilder().setStatement(cursor.getString(0)).build());
-          }
-        }
-      }
-    }
-
-    return tables;
-  }
-
-  private static int exportTable(@NonNull   String table,
-                                 @NonNull   SQLiteDatabase input,
-                                 @NonNull   BackupFrameOutputStream outputStream,
-                                 @Nullable  Predicate<Cursor> predicate,
-                                 @Nullable  Consumer<Cursor> postProcess,
-                                            int count)
-      throws IOException
-  {
-    String template = "INSERT INTO " + table + " VALUES ";
-
-    try (Cursor cursor = input.rawQuery("SELECT * FROM " + table, null)) {
-      while (cursor != null && cursor.moveToNext()) {
-        EventBus.getDefault().post(new BackupEvent(BackupEvent.Type.PROGRESS, ++count));
-
-        if (predicate == null || predicate.test(cursor)) {
-          StringBuilder                     statement        = new StringBuilder(template);
-          BackupProtos.SqlStatement.Builder statementBuilder = BackupProtos.SqlStatement.newBuilder();
-
-          statement.append('(');
-
-          for (int i=0;i<cursor.getColumnCount();i++) {
-            statement.append('?');
-
-            if (cursor.getType(i) == Cursor.FIELD_TYPE_STRING) {
-              statementBuilder.addParameters(BackupProtos.SqlStatement.SqlParameter.newBuilder().setStringParamter(cursor.getString(i)));
-            } else if (cursor.getType(i) == Cursor.FIELD_TYPE_FLOAT) {
-              statementBuilder.addParameters(BackupProtos.SqlStatement.SqlParameter.newBuilder().setDoubleParameter(cursor.getDouble(i)));
-            } else if (cursor.getType(i) == Cursor.FIELD_TYPE_INTEGER) {
-              statementBuilder.addParameters(BackupProtos.SqlStatement.SqlParameter.newBuilder().setIntegerParameter(cursor.getLong(i)));
-            } else if (cursor.getType(i) == Cursor.FIELD_TYPE_BLOB) {
-              statementBuilder.addParameters(BackupProtos.SqlStatement.SqlParameter.newBuilder().setBlobParameter(ByteString.copyFrom(cursor.getBlob(i))));
-            } else if (cursor.getType(i) == Cursor.FIELD_TYPE_NULL) {
-              statementBuilder.addParameters(BackupProtos.SqlStatement.SqlParameter.newBuilder().setNullparameter(true));
-            } else {
-              throw new AssertionError("unknown type?"  + cursor.getType(i));
-            }
-
-            if (i < cursor.getColumnCount()-1) {
-              statement.append(',');
-            }
-          }
-
-          statement.append(')');
-
-          outputStream.write(statementBuilder.setStatement(statement.toString()).build());
-
-          if (postProcess != null) postProcess.accept(cursor);
-        }
-      }
-    }
-
-    return count;
-  }
-
-  private static void exportAttachment(@NonNull AttachmentSecret attachmentSecret, @NonNull Cursor cursor, @NonNull BackupFrameOutputStream outputStream) {
-    try {
-      long rowId    = cursor.getLong(cursor.getColumnIndexOrThrow(AttachmentDatabase.ROW_ID));
-      long uniqueId = cursor.getLong(cursor.getColumnIndexOrThrow(AttachmentDatabase.UNIQUE_ID));
-      long size     = cursor.getLong(cursor.getColumnIndexOrThrow(AttachmentDatabase.SIZE));
-
-      String data   = cursor.getString(cursor.getColumnIndexOrThrow(AttachmentDatabase.DATA));
-      byte[] random = cursor.getBlob(cursor.getColumnIndexOrThrow(AttachmentDatabase.DATA_RANDOM));
-
-      if (!TextUtils.isEmpty(data) && size <= 0) {
-        size = calculateVeryOldStreamLength(attachmentSecret, random, data);
-      }
-
-      if (!TextUtils.isEmpty(data) && size > 0) {
-        InputStream inputStream;
-
-        if (random != null && random.length == 32) inputStream = ModernDecryptingPartInputStream.createFor(attachmentSecret, random, new File(data), 0);
-        else                                       inputStream = ClassicDecryptingPartInputStream.createFor(attachmentSecret, new File(data));
-
-        outputStream.write(new AttachmentId(rowId, uniqueId), inputStream, size);
-      }
-    } catch (IOException e) {
-      Log.w(TAG, e);
-    }
-  }
-
-  private static void exportSticker(@NonNull AttachmentSecret attachmentSecret, @NonNull Cursor cursor, @NonNull BackupFrameOutputStream outputStream) {
-    try {
-      long rowId    = cursor.getLong(cursor.getColumnIndexOrThrow(StickerDatabase._ID));
-      long size     = cursor.getLong(cursor.getColumnIndexOrThrow(StickerDatabase.FILE_LENGTH));
-
-      String data   = cursor.getString(cursor.getColumnIndexOrThrow(StickerDatabase.FILE_PATH));
-      byte[] random = cursor.getBlob(cursor.getColumnIndexOrThrow(StickerDatabase.FILE_RANDOM));
-
-      if (!TextUtils.isEmpty(data) && size > 0) {
-        try (InputStream inputStream = ModernDecryptingPartInputStream.createFor(attachmentSecret, random, new File(data), 0)) {
-          outputStream.writeSticker(rowId, inputStream, size);
-        }
-      }
-    } catch (IOException e) {
-      Log.w(TAG, e);
-    }
-  }
-
-  private static long calculateVeryOldStreamLength(@NonNull AttachmentSecret attachmentSecret, @Nullable byte[] random, @NonNull String data) throws IOException {
-    long result = 0;
-    InputStream inputStream;
-
-    if (random != null && random.length == 32) inputStream = ModernDecryptingPartInputStream.createFor(attachmentSecret, random, new File(data), 0);
-    else                                       inputStream = ClassicDecryptingPartInputStream.createFor(attachmentSecret, new File(data));
-
-    int read;
-    byte[] buffer = new byte[8192];
-
-    while ((read = inputStream.read(buffer, 0, buffer.length)) != -1) {
-      result += read;
-    }
-
-    return result;
-  }
-
-  private static boolean isForNonExpiringMessage(@NonNull SQLiteDatabase db, long mmsId) {
-    String[] columns = new String[] { MmsDatabase.EXPIRES_IN };
-    String   where   = MmsDatabase.ID + " = ?";
-    String[] args    = new String[] { String.valueOf(mmsId) };
-
-    try (Cursor mmsCursor = db.query(MmsDatabase.TABLE_NAME, columns, where, args, null, null, null)) {
-      if (mmsCursor != null && mmsCursor.moveToFirst()) {
-        return mmsCursor.getLong(0) == 0;
-      }
-    }
-
-    return false;
-  }
-
-
-  private static class BackupFrameOutputStream extends BackupStream implements Closeable, Flushable {
-
-    private final OutputStream outputStream;
-    private final Cipher       cipher;
-    private final Mac          mac;
-
-    private final byte[]       cipherKey;
-    private final byte[]       macKey;
-
-    private byte[] iv;
-    private int    counter;
-
-    private BackupFrameOutputStream(@NonNull OutputStream outputStream, @NonNull String passphrase) throws IOException {
-      try {
-        byte[]   salt    = Util.getSecretBytes(32);
-        byte[]   key     = getBackupKey(passphrase, salt);
-        byte[]   derived = new HKDFv3().deriveSecrets(key, "Backup Export".getBytes(), 64);
-        byte[][] split   = ByteUtil.split(derived, 32, 32);
-
-        this.cipherKey = split[0];
-        this.macKey    = split[1];
-
-        this.cipher       = Cipher.getInstance("AES/CTR/NoPadding");
-        this.mac          = Mac.getInstance("HmacSHA256");
-        this.outputStream = outputStream;
-        this.iv           = Util.getSecretBytes(16);
-        this.counter      = Conversions.byteArrayToInt(iv);
-
-        mac.init(new SecretKeySpec(macKey, "HmacSHA256"));
-
-        byte[] header = BackupProtos.BackupFrame.newBuilder().setHeader(BackupProtos.Header.newBuilder()
-                                                                                           .setIv(ByteString.copyFrom(iv))
-                                                                                           .setSalt(ByteString.copyFrom(salt)))
-                                                .build().toByteArray();
-
-        outputStream.write(Conversions.intToByteArray(header.length));
-        outputStream.write(header);
-      } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException e) {
-        throw new AssertionError(e);
-      }
-    }
-
-    public void write(BackupProtos.SharedPreference preference) throws IOException {
-      write(outputStream, BackupProtos.BackupFrame.newBuilder().setPreference(preference).build());
-    }
-
-    public void write(BackupProtos.SqlStatement statement) throws IOException {
-      write(outputStream, BackupProtos.BackupFrame.newBuilder().setStatement(statement).build());
-    }
-
-    public void write(@NonNull String avatarName, @NonNull InputStream in, long size) throws IOException {
-      write(outputStream, BackupProtos.BackupFrame.newBuilder()
-                                                  .setAvatar(BackupProtos.Avatar.newBuilder()
-                                                                                .setName(avatarName)
-                                                                                .setLength(Util.toIntExact(size))
-                                                                                .build())
-                                                  .build());
-
-      writeStream(in);
-    }
-
-    public void write(@NonNull AttachmentId attachmentId, @NonNull InputStream in, long size) throws IOException {
-      write(outputStream, BackupProtos.BackupFrame.newBuilder()
-                                                  .setAttachment(BackupProtos.Attachment.newBuilder()
-                                                                                        .setRowId(attachmentId.getRowId())
-                                                                                        .setAttachmentId(attachmentId.getUniqueId())
-                                                                                        .setLength(Util.toIntExact(size))
-                                                                                        .build())
-                                                  .build());
-
-      writeStream(in);
-    }
-
-    public void writeSticker(long rowId, @NonNull InputStream in, long size) throws IOException {
-      write(outputStream, BackupProtos.BackupFrame.newBuilder()
-                                                  .setSticker(BackupProtos.Sticker.newBuilder()
-                                                                                  .setRowId(rowId)
-                                                                                  .setLength(Util.toIntExact(size))
-                                                                                  .build())
-                                                  .build());
-
-      writeStream(in);
-    }
-
-    void writeDatabaseVersion(int version) throws IOException {
-      write(outputStream, BackupProtos.BackupFrame.newBuilder()
-                                                  .setVersion(BackupProtos.DatabaseVersion.newBuilder().setVersion(version))
-                                                  .build());
-    }
-
-    void writeEnd() throws IOException {
-      write(outputStream, BackupProtos.BackupFrame.newBuilder().setEnd(true).build());
-    }
-
-    private void writeStream(@NonNull InputStream inputStream) throws IOException {
-      try {
-        Conversions.intToByteArray(iv, 0, counter++);
-        cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(cipherKey, "AES"), new IvParameterSpec(iv));
-        mac.update(iv);
-
-        byte[] buffer = new byte[8192];
-        int read;
-
-        while ((read = inputStream.read(buffer)) != -1) {
-          byte[] ciphertext = cipher.update(buffer, 0, read);
-
-          if (ciphertext != null) {
-            outputStream.write(ciphertext);
-            mac.update(ciphertext);
-          }
-        }
-
-        byte[] remainder = cipher.doFinal();
-        outputStream.write(remainder);
-        mac.update(remainder);
-
-        byte[] attachmentDigest = mac.doFinal();
-        outputStream.write(attachmentDigest, 0, 10);
-      } catch (InvalidKeyException | InvalidAlgorithmParameterException | IllegalBlockSizeException | BadPaddingException e) {
-        throw new AssertionError(e);
-      }
-    }
-
-    private void write(@NonNull OutputStream out, @NonNull BackupProtos.BackupFrame frame) throws IOException {
-      try {
-        Conversions.intToByteArray(iv, 0, counter++);
-        cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(cipherKey, "AES"), new IvParameterSpec(iv));
-
-        byte[] frameCiphertext = cipher.doFinal(frame.toByteArray());
-        byte[] frameMac        = mac.doFinal(frameCiphertext);
-        byte[] length          = Conversions.intToByteArray(frameCiphertext.length + 10);
-
-        out.write(length);
-        out.write(frameCiphertext);
-        out.write(frameMac, 0, 10);
-      } catch (InvalidKeyException | InvalidAlgorithmParameterException | IllegalBlockSizeException | BadPaddingException e) {
-        throw new AssertionError(e);
-      }
-    }
-
-    @Override
-    public void flush() throws IOException {
-      outputStream.flush();
-    }
-
-    @Override
-    public void close() throws IOException {
-      outputStream.close();
-    }
-  }
-}
diff --git a/src/org/thoughtcrime/securesms/backup/FullBackupExporter.kt b/src/org/thoughtcrime/securesms/backup/FullBackupExporter.kt
new file mode 100644
index 0000000000..8f69f59147
--- /dev/null
+++ b/src/org/thoughtcrime/securesms/backup/FullBackupExporter.kt
@@ -0,0 +1,449 @@
+package org.thoughtcrime.securesms.backup
+
+import android.content.Context
+import android.database.Cursor
+import android.net.Uri
+import android.text.TextUtils
+import androidx.annotation.WorkerThread
+import com.annimon.stream.function.Consumer
+import com.annimon.stream.function.Predicate
+import com.google.protobuf.ByteString
+import net.sqlcipher.database.SQLiteDatabase
+import org.greenrobot.eventbus.EventBus
+import org.thoughtcrime.securesms.attachments.AttachmentId
+import org.thoughtcrime.securesms.backup.BackupProtos.*
+import org.thoughtcrime.securesms.crypto.AttachmentSecret
+import org.thoughtcrime.securesms.crypto.ClassicDecryptingPartInputStream
+import org.thoughtcrime.securesms.crypto.IdentityKeyUtil
+import org.thoughtcrime.securesms.crypto.ModernDecryptingPartInputStream
+import org.thoughtcrime.securesms.database.*
+import org.thoughtcrime.securesms.logging.Log
+import org.thoughtcrime.securesms.loki.database.LokiAPIDatabase
+import org.thoughtcrime.securesms.loki.database.LokiBackupFilesDatabase
+import org.thoughtcrime.securesms.profiles.AvatarHelper
+import org.thoughtcrime.securesms.util.BackupUtil
+import org.thoughtcrime.securesms.util.Conversions
+import org.thoughtcrime.securesms.util.TextSecurePreferences
+import org.thoughtcrime.securesms.util.Util
+import org.whispersystems.libsignal.kdf.HKDFv3
+import org.whispersystems.libsignal.util.ByteUtil
+import java.io.*
+import java.lang.Exception
+import java.security.InvalidAlgorithmParameterException
+import java.security.InvalidKeyException
+import java.security.NoSuchAlgorithmException
+import java.util.*
+import javax.crypto.*
+import javax.crypto.spec.IvParameterSpec
+import javax.crypto.spec.SecretKeySpec
+
+object FullBackupExporter {
+    private val TAG = FullBackupExporter::class.java.simpleName
+
+    @JvmStatic
+    @WorkerThread
+    @Throws(IOException::class)
+    fun export(context: Context,
+               attachmentSecret: AttachmentSecret,
+               input: SQLiteDatabase,
+               fileUri: Uri,
+               passphrase: String) {
+
+        val baseOutputStream = context.contentResolver.openOutputStream(fileUri)
+                ?: throw IOException("Cannot open an output stream for the file URI: $fileUri")
+
+        var count = 0
+        try {
+            BackupFrameOutputStream(baseOutputStream, passphrase).use { outputStream ->
+                outputStream.writeDatabaseVersion(input.version)
+                val tables = exportSchema(input, outputStream)
+                for (table in tables) if (shouldExportTable(table)) {
+                    count = when (table) {
+                        SmsDatabase.TABLE_NAME, MmsDatabase.TABLE_NAME -> {
+                            exportTable(table, input, outputStream,
+                                    { cursor: Cursor ->
+                                        cursor.getInt(cursor.getColumnIndexOrThrow(MmsSmsColumns.EXPIRES_IN)) <= 0
+                                    },
+                                    null,
+                                    count)
+                        }
+                        GroupReceiptDatabase.TABLE_NAME -> {
+                            exportTable(table, input, outputStream,
+                                    { cursor: Cursor ->
+                                        isForNonExpiringMessage(input, cursor.getLong(cursor.getColumnIndexOrThrow(GroupReceiptDatabase.MMS_ID)))
+                                    },
+                                    null,
+                                    count)
+                        }
+                        AttachmentDatabase.TABLE_NAME -> {
+                            exportTable(table, input, outputStream,
+                                    { cursor: Cursor ->
+                                        isForNonExpiringMessage(input, cursor.getLong(cursor.getColumnIndexOrThrow(AttachmentDatabase.MMS_ID)))
+                                    },
+                                    { cursor: Cursor ->
+                                        exportAttachment(attachmentSecret, cursor, outputStream)
+                                    },
+                                    count)
+                        }
+                        StickerDatabase.TABLE_NAME -> {
+                            exportTable(table, input, outputStream,
+                                    { true },
+                                    { cursor: Cursor -> exportSticker(attachmentSecret, cursor, outputStream) },
+                                    count)
+                        }
+                        else -> {
+                            exportTable(table, input, outputStream, null, null, count)
+                        }
+                    }
+                }
+                for (preference in IdentityKeyUtil.getBackupRecords(context)) {
+                    EventBus.getDefault().post(BackupEvent.createProgress(++count))
+                    outputStream.writePreferenceEntry(preference)
+                }
+                for (preference in TextSecurePreferences.getBackupRecords(context)) {
+                    EventBus.getDefault().post(BackupEvent.createProgress(++count))
+                    outputStream.writePreferenceEntry(preference)
+                }
+                for (avatar in AvatarHelper.getAvatarFiles(context)) {
+                    EventBus.getDefault().post(BackupEvent.createProgress(++count))
+                    outputStream.writeAvatar(avatar.name, FileInputStream(avatar), avatar.length())
+                }
+                outputStream.writeEnd()
+            }
+            EventBus.getDefault().post(BackupEvent.createFinished())
+        } catch (e: Exception) {
+            Log.e(TAG, "Failed to make full backup.", e)
+            EventBus.getDefault().post(BackupEvent.createFinished(e))
+            throw e
+        }
+    }
+
+    private inline fun shouldExportTable(table: String): Boolean {
+        return  table != SignedPreKeyDatabase.TABLE_NAME &&
+                table != OneTimePreKeyDatabase.TABLE_NAME &&
+                table != SessionDatabase.TABLE_NAME &&
+                table != PushDatabase.TABLE_NAME &&
+
+                table != LokiBackupFilesDatabase.TABLE_NAME &&
+                table != LokiAPIDatabase.openGroupProfilePictureTable &&
+
+                table != JobDatabase.Jobs.TABLE_NAME &&
+                table != JobDatabase.Constraints.TABLE_NAME &&
+                table != JobDatabase.Dependencies.TABLE_NAME &&
+
+                !table.startsWith(SearchDatabase.SMS_FTS_TABLE_NAME) &&
+                !table.startsWith(SearchDatabase.MMS_FTS_TABLE_NAME) &&
+                !table.startsWith("sqlite_")
+    }
+
+    @Throws(IOException::class)
+    private fun exportSchema(input: SQLiteDatabase, outputStream: BackupFrameOutputStream): List<String> {
+        val tables: MutableList<String> = LinkedList()
+        input.rawQuery("SELECT sql, name, type FROM sqlite_master", null).use { cursor ->
+            while (cursor != null && cursor.moveToNext()) {
+                val sql = cursor.getString(0)
+                val name = cursor.getString(1)
+                val type = cursor.getString(2)
+                if (sql != null) {
+                    val isSmsFtsSecretTable = name != null && name != SearchDatabase.SMS_FTS_TABLE_NAME && name.startsWith(SearchDatabase.SMS_FTS_TABLE_NAME)
+                    val isMmsFtsSecretTable = name != null && name != SearchDatabase.MMS_FTS_TABLE_NAME && name.startsWith(SearchDatabase.MMS_FTS_TABLE_NAME)
+                    if (!isSmsFtsSecretTable && !isMmsFtsSecretTable) {
+                        if ("table" == type) {
+                            tables.add(name)
+                        }
+                        outputStream.writeSql(SqlStatement.newBuilder().setStatement(cursor.getString(0)).build())
+                    }
+                }
+            }
+        }
+        return tables
+    }
+
+    @Throws(IOException::class)
+    private fun exportTable(table: String,
+                            input: SQLiteDatabase,
+                            outputStream: BackupFrameOutputStream,
+                            predicate: Predicate<Cursor>?,
+                            postProcess: Consumer<Cursor>?,
+                            count: Int): Int {
+        var count = count
+        val template = "INSERT INTO $table VALUES "
+        input.rawQuery("SELECT * FROM $table", null).use { cursor ->
+            while (cursor != null && cursor.moveToNext()) {
+                EventBus.getDefault().post(BackupEvent.createProgress(++count))
+                if (predicate != null && !predicate.test(cursor)) continue
+
+                val statement = StringBuilder(template)
+                val statementBuilder = SqlStatement.newBuilder()
+                statement.append('(')
+                for (i in 0 until cursor.columnCount) {
+                    statement.append('?')
+                    when (cursor.getType(i)) {
+                        Cursor.FIELD_TYPE_STRING -> {
+                            statementBuilder.addParameters(SqlStatement.SqlParameter.newBuilder()
+                                    .setStringParamter(cursor.getString(i)))
+                        }
+                        Cursor.FIELD_TYPE_FLOAT -> {
+                            statementBuilder.addParameters(SqlStatement.SqlParameter.newBuilder()
+                                    .setDoubleParameter(cursor.getDouble(i)))
+                        }
+                        Cursor.FIELD_TYPE_INTEGER -> {
+                            statementBuilder.addParameters(SqlStatement.SqlParameter.newBuilder()
+                                    .setIntegerParameter(cursor.getLong(i)))
+                        }
+                        Cursor.FIELD_TYPE_BLOB -> {
+                            statementBuilder.addParameters(SqlStatement.SqlParameter.newBuilder()
+                                    .setBlobParameter(ByteString.copyFrom(cursor.getBlob(i))))
+                        }
+                        Cursor.FIELD_TYPE_NULL -> {
+                            statementBuilder.addParameters(SqlStatement.SqlParameter.newBuilder()
+                                    .setNullparameter(true))
+                        }
+                        else -> {
+                            throw AssertionError("unknown type?" + cursor.getType(i))
+                        }
+                    }
+                    if (i < cursor.columnCount - 1) {
+                        statement.append(',')
+                    }
+                }
+                statement.append(')')
+                outputStream.writeSql(statementBuilder.setStatement(statement.toString()).build())
+                postProcess?.accept(cursor)
+            }
+        }
+        return count
+    }
+
+    private fun exportAttachment(attachmentSecret: AttachmentSecret, cursor: Cursor, outputStream: BackupFrameOutputStream) {
+        try {
+            val rowId = cursor.getLong(cursor.getColumnIndexOrThrow(AttachmentDatabase.ROW_ID))
+            val uniqueId = cursor.getLong(cursor.getColumnIndexOrThrow(AttachmentDatabase.UNIQUE_ID))
+            var size = cursor.getLong(cursor.getColumnIndexOrThrow(AttachmentDatabase.SIZE))
+            val data = cursor.getString(cursor.getColumnIndexOrThrow(AttachmentDatabase.DATA))
+            val random = cursor.getBlob(cursor.getColumnIndexOrThrow(AttachmentDatabase.DATA_RANDOM))
+            if (!TextUtils.isEmpty(data) && size <= 0) {
+                size = calculateVeryOldStreamLength(attachmentSecret, random, data)
+            }
+            if (!TextUtils.isEmpty(data) && size > 0) {
+                val inputStream: InputStream = if (random != null && random.size == 32) {
+                    ModernDecryptingPartInputStream.createFor(attachmentSecret, random, File(data), 0)
+                } else {
+                    ClassicDecryptingPartInputStream.createFor(attachmentSecret, File(data))
+                }
+                outputStream.writeAttachment(AttachmentId(rowId, uniqueId), inputStream, size)
+            }
+        } catch (e: IOException) {
+            Log.w(TAG, e)
+        }
+    }
+
+    private fun exportSticker(attachmentSecret: AttachmentSecret, cursor: Cursor, outputStream: BackupFrameOutputStream) {
+        try {
+            val rowId = cursor.getLong(cursor.getColumnIndexOrThrow(StickerDatabase._ID))
+            val size = cursor.getLong(cursor.getColumnIndexOrThrow(StickerDatabase.FILE_LENGTH))
+            val data = cursor.getString(cursor.getColumnIndexOrThrow(StickerDatabase.FILE_PATH))
+            val random = cursor.getBlob(cursor.getColumnIndexOrThrow(StickerDatabase.FILE_RANDOM))
+            if (!TextUtils.isEmpty(data) && size > 0) {
+                ModernDecryptingPartInputStream.createFor(attachmentSecret, random, File(data), 0).use { inputStream -> outputStream.writeSticker(rowId, inputStream, size) }
+            }
+        } catch (e: IOException) {
+            Log.w(TAG, e)
+        }
+    }
+
+    @Throws(IOException::class)
+    private fun calculateVeryOldStreamLength(attachmentSecret: AttachmentSecret, random: ByteArray?, data: String): Long {
+        var result: Long = 0
+        val inputStream: InputStream = if (random != null && random.size == 32) {
+            ModernDecryptingPartInputStream.createFor(attachmentSecret, random, File(data), 0)
+        } else {
+            ClassicDecryptingPartInputStream.createFor(attachmentSecret, File(data))
+        }
+        var read: Int
+        val buffer = ByteArray(8192)
+        while (inputStream.read(buffer, 0, buffer.size).also { read = it } != -1) {
+            result += read.toLong()
+        }
+        return result
+    }
+
+    private fun isForNonExpiringMessage(db: SQLiteDatabase, mmsId: Long): Boolean {
+        val columns = arrayOf(MmsDatabase.EXPIRES_IN)
+        val where = MmsDatabase.ID + " = ?"
+        val args = arrayOf(mmsId.toString())
+        db.query(MmsDatabase.TABLE_NAME, columns, where, args, null, null, null).use { mmsCursor ->
+            if (mmsCursor != null && mmsCursor.moveToFirst()) {
+                return mmsCursor.getLong(0) == 0L
+            }
+        }
+        return false
+    }
+
+    private class BackupFrameOutputStream : Closeable, Flushable {
+
+        private val outputStream: OutputStream
+        private var cipher: Cipher
+        private var mac: Mac
+        private val cipherKey: ByteArray
+        private val macKey: ByteArray
+        private val iv: ByteArray
+
+        private var counter: Int = 0
+
+        constructor(outputStream: OutputStream, passphrase: String) : super() {
+            try {
+                val salt = Util.getSecretBytes(32)
+                val key = BackupUtil.computeBackupKey(passphrase, salt)
+                val derived = HKDFv3().deriveSecrets(key, "Backup Export".toByteArray(), 64)
+                val split = ByteUtil.split(derived, 32, 32)
+                cipherKey = split[0]
+                macKey = split[1]
+                cipher = Cipher.getInstance("AES/CTR/NoPadding")
+                mac = Mac.getInstance("HmacSHA256")
+                this.outputStream = outputStream
+                iv = Util.getSecretBytes(16)
+                counter = Conversions.byteArrayToInt(iv)
+                mac.init(SecretKeySpec(macKey, "HmacSHA256"))
+                val header = BackupFrame.newBuilder().setHeader(Header.newBuilder()
+                        .setIv(ByteString.copyFrom(iv))
+                        .setSalt(ByteString.copyFrom(salt)))
+                        .build().toByteArray()
+                outputStream.write(Conversions.intToByteArray(header.size))
+                outputStream.write(header)
+            } catch (e: Exception) {
+                when (e) {
+                    is NoSuchAlgorithmException,
+                    is NoSuchPaddingException,
+                    is InvalidKeyException -> {
+                        throw AssertionError(e)
+                    }
+                    else -> throw e
+                }
+            }
+        }
+
+        @Throws(IOException::class)
+        fun writeSql(statement: SqlStatement) {
+            write(outputStream, BackupFrame.newBuilder().setStatement(statement).build())
+        }
+
+        @Throws(IOException::class)
+        fun writePreferenceEntry(preference: SharedPreference?) {
+            write(outputStream, BackupFrame.newBuilder().setPreference(preference).build())
+        }
+
+        @Throws(IOException::class)
+        fun writeAvatar(avatarName: String, inputStream: InputStream, size: Long) {
+            write(outputStream, BackupFrame.newBuilder()
+                    .setAvatar(Avatar.newBuilder()
+                            .setName(avatarName)
+                            .setLength(Util.toIntExact(size))
+                            .build())
+                    .build())
+            writeStream(inputStream)
+        }
+
+        @Throws(IOException::class)
+        fun writeAttachment(attachmentId: AttachmentId, inputStream: InputStream, size: Long) {
+            write(outputStream, BackupFrame.newBuilder()
+                    .setAttachment(Attachment.newBuilder()
+                            .setRowId(attachmentId.rowId)
+                            .setAttachmentId(attachmentId.uniqueId)
+                            .setLength(Util.toIntExact(size))
+                            .build())
+                    .build())
+            writeStream(inputStream)
+        }
+
+        @Throws(IOException::class)
+        fun writeSticker(rowId: Long, inputStream: InputStream, size: Long) {
+            write(outputStream, BackupFrame.newBuilder()
+                    .setSticker(Sticker.newBuilder()
+                            .setRowId(rowId)
+                            .setLength(Util.toIntExact(size))
+                            .build())
+                    .build())
+            writeStream(inputStream)
+        }
+
+        @Throws(IOException::class)
+        fun writeDatabaseVersion(version: Int) {
+            write(outputStream, BackupFrame.newBuilder()
+                    .setVersion(DatabaseVersion.newBuilder().setVersion(version))
+                    .build())
+        }
+
+        @Throws(IOException::class)
+        fun writeEnd() {
+            write(outputStream, BackupFrame.newBuilder().setEnd(true).build())
+        }
+
+        @Throws(IOException::class)
+        private fun writeStream(inputStream: InputStream) {
+            try {
+                Conversions.intToByteArray(iv, 0, counter++)
+                cipher.init(Cipher.ENCRYPT_MODE, SecretKeySpec(cipherKey, "AES"), IvParameterSpec(iv))
+                mac.update(iv)
+                val buffer = ByteArray(8192)
+                var read: Int
+                while (inputStream.read(buffer).also { read = it } != -1) {
+                    val ciphertext = cipher.update(buffer, 0, read)
+                    if (ciphertext != null) {
+                        outputStream.write(ciphertext)
+                        mac.update(ciphertext)
+                    }
+                }
+                val remainder = cipher.doFinal()
+                outputStream.write(remainder)
+                mac.update(remainder)
+                val attachmentDigest = mac.doFinal()
+                outputStream.write(attachmentDigest, 0, 10)
+            } catch (e: Exception) {
+                when (e) {
+                    is InvalidKeyException,
+                    is InvalidAlgorithmParameterException,
+                    is IllegalBlockSizeException,
+                    is BadPaddingException -> {
+                        throw AssertionError(e)
+                    }
+                    else -> throw e
+                }
+            }
+        }
+
+        @Throws(IOException::class)
+        private fun write(out: OutputStream, frame: BackupFrame) {
+            try {
+                Conversions.intToByteArray(iv, 0, counter++)
+                cipher.init(Cipher.ENCRYPT_MODE, SecretKeySpec(cipherKey, "AES"), IvParameterSpec(iv))
+                val frameCiphertext = cipher.doFinal(frame.toByteArray())
+                val frameMac = mac.doFinal(frameCiphertext)
+                val length = Conversions.intToByteArray(frameCiphertext.size + 10)
+                out.write(length)
+                out.write(frameCiphertext)
+                out.write(frameMac, 0, 10)
+            } catch (e: Exception) {
+                when (e) {
+                    is InvalidKeyException,
+                    is InvalidAlgorithmParameterException,
+                    is IllegalBlockSizeException,
+                    is BadPaddingException -> {
+                        throw AssertionError(e)
+                    }
+                    else -> throw e
+                }
+            }
+        }
+
+        @Throws(IOException::class)
+        override fun flush() {
+            outputStream.flush()
+        }
+
+        @Throws(IOException::class)
+        override fun close() {
+            outputStream.close()
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/org/thoughtcrime/securesms/backup/FullBackupImporter.java b/src/org/thoughtcrime/securesms/backup/FullBackupImporter.java
deleted file mode 100644
index 96ee5b9f8c..0000000000
--- a/src/org/thoughtcrime/securesms/backup/FullBackupImporter.java
+++ /dev/null
@@ -1,359 +0,0 @@
-package org.thoughtcrime.securesms.backup;
-
-
-import android.annotation.SuppressLint;
-import android.content.ContentValues;
-import android.content.Context;
-import android.content.SharedPreferences;
-import android.database.Cursor;
-import androidx.annotation.NonNull;
-import android.util.Pair;
-
-import net.sqlcipher.database.SQLiteDatabase;
-
-import org.greenrobot.eventbus.EventBus;
-import org.thoughtcrime.securesms.attachments.AttachmentId;
-import org.thoughtcrime.securesms.backup.BackupProtos.Attachment;
-import org.thoughtcrime.securesms.backup.BackupProtos.BackupFrame;
-import org.thoughtcrime.securesms.backup.BackupProtos.DatabaseVersion;
-import org.thoughtcrime.securesms.backup.BackupProtos.SharedPreference;
-import org.thoughtcrime.securesms.backup.BackupProtos.SqlStatement;
-import org.thoughtcrime.securesms.backup.BackupProtos.Sticker;
-import org.thoughtcrime.securesms.crypto.AttachmentSecret;
-import org.thoughtcrime.securesms.crypto.ModernEncryptingPartOutputStream;
-import org.thoughtcrime.securesms.database.Address;
-import org.thoughtcrime.securesms.database.AttachmentDatabase;
-import org.thoughtcrime.securesms.database.DatabaseFactory;
-import org.thoughtcrime.securesms.database.GroupReceiptDatabase;
-import org.thoughtcrime.securesms.database.MmsDatabase;
-import org.thoughtcrime.securesms.database.SearchDatabase;
-import org.thoughtcrime.securesms.database.StickerDatabase;
-import org.thoughtcrime.securesms.database.ThreadDatabase;
-import org.thoughtcrime.securesms.logging.Log;
-import org.thoughtcrime.securesms.profiles.AvatarHelper;
-import org.thoughtcrime.securesms.util.Conversions;
-import org.thoughtcrime.securesms.util.Util;
-import org.whispersystems.libsignal.kdf.HKDFv3;
-import org.whispersystems.libsignal.util.ByteUtil;
-
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
-import java.security.InvalidAlgorithmParameterException;
-import java.security.InvalidKeyException;
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
-import java.util.LinkedList;
-import java.util.List;
-
-import javax.crypto.BadPaddingException;
-import javax.crypto.Cipher;
-import javax.crypto.IllegalBlockSizeException;
-import javax.crypto.Mac;
-import javax.crypto.NoSuchPaddingException;
-import javax.crypto.spec.IvParameterSpec;
-import javax.crypto.spec.SecretKeySpec;
-
-public class FullBackupImporter extends FullBackupBase {
-
-  @SuppressWarnings("unused")
-  private static final String TAG = FullBackupImporter.class.getSimpleName();
-
-  public static void importFile(@NonNull Context context, @NonNull AttachmentSecret attachmentSecret,
-                                @NonNull SQLiteDatabase db, @NonNull File file, @NonNull String passphrase)
-      throws IOException
-  {
-    BackupRecordInputStream inputStream = new BackupRecordInputStream(file, passphrase);
-    int                     count       = 0;
-
-    try {
-      db.beginTransaction();
-
-      dropAllTables(db);
-
-      BackupFrame frame;
-
-      while (!(frame = inputStream.readFrame()).getEnd()) {
-        if (count++ % 100 == 0) EventBus.getDefault().post(new BackupEvent(BackupEvent.Type.PROGRESS, count));
-
-        if      (frame.hasVersion())    processVersion(db, frame.getVersion());
-        else if (frame.hasStatement())  processStatement(db, frame.getStatement());
-        else if (frame.hasPreference()) processPreference(context, frame.getPreference());
-        else if (frame.hasAttachment()) processAttachment(context, attachmentSecret, db, frame.getAttachment(), inputStream);
-        else if (frame.hasSticker())    processSticker(context, attachmentSecret, db, frame.getSticker(), inputStream);
-        else if (frame.hasAvatar())     processAvatar(context, frame.getAvatar(), inputStream);
-      }
-
-      trimEntriesForExpiredMessages(context, db);
-
-      db.setTransactionSuccessful();
-    } finally {
-      db.endTransaction();
-    }
-
-    EventBus.getDefault().post(new BackupEvent(BackupEvent.Type.FINISHED, count));
-  }
-
-  private static void processVersion(@NonNull SQLiteDatabase db, DatabaseVersion version) throws IOException {
-    if (version.getVersion() > db.getVersion()) {
-      throw new DatabaseDowngradeException(db.getVersion(), version.getVersion());
-    }
-
-    db.setVersion(version.getVersion());
-  }
-
-  private static void processStatement(@NonNull SQLiteDatabase db, SqlStatement statement) {
-    boolean isForSmsFtsSecretTable = statement.getStatement().contains(SearchDatabase.SMS_FTS_TABLE_NAME + "_");
-    boolean isForMmsFtsSecretTable = statement.getStatement().contains(SearchDatabase.MMS_FTS_TABLE_NAME + "_");
-    boolean isForSqliteSecretTable = statement.getStatement().toLowerCase().startsWith("create table sqlite_");
-
-    if (isForSmsFtsSecretTable || isForMmsFtsSecretTable || isForSqliteSecretTable) {
-      Log.i(TAG, "Ignoring import for statement: " + statement.getStatement());
-      return;
-    }
-
-    List<Object> parameters = new LinkedList<>();
-
-    for (SqlStatement.SqlParameter parameter : statement.getParametersList()) {
-      if      (parameter.hasStringParamter())   parameters.add(parameter.getStringParamter());
-      else if (parameter.hasDoubleParameter())  parameters.add(parameter.getDoubleParameter());
-      else if (parameter.hasIntegerParameter()) parameters.add(parameter.getIntegerParameter());
-      else if (parameter.hasBlobParameter())    parameters.add(parameter.getBlobParameter().toByteArray());
-      else if (parameter.hasNullparameter())    parameters.add(null);
-    }
-
-    if (parameters.size() > 0) db.execSQL(statement.getStatement(), parameters.toArray());
-    else                       db.execSQL(statement.getStatement());
-  }
-
-  private static void processAttachment(@NonNull Context context, @NonNull AttachmentSecret attachmentSecret, @NonNull SQLiteDatabase db, @NonNull Attachment attachment, BackupRecordInputStream inputStream)
-      throws IOException
-  {
-    File partsDirectory = context.getDir(AttachmentDatabase.DIRECTORY, Context.MODE_PRIVATE);
-    File dataFile       = File.createTempFile("part", ".mms", partsDirectory);
-
-    Pair<byte[], OutputStream> output = ModernEncryptingPartOutputStream.createFor(attachmentSecret, dataFile, false);
-
-    inputStream.readAttachmentTo(output.second, attachment.getLength());
-
-    ContentValues contentValues = new ContentValues();
-    contentValues.put(AttachmentDatabase.DATA, dataFile.getAbsolutePath());
-    contentValues.put(AttachmentDatabase.THUMBNAIL, (String)null);
-    contentValues.put(AttachmentDatabase.DATA_RANDOM, output.first);
-
-    db.update(AttachmentDatabase.TABLE_NAME, contentValues,
-              AttachmentDatabase.ROW_ID + " = ? AND " + AttachmentDatabase.UNIQUE_ID + " = ?",
-              new String[] {String.valueOf(attachment.getRowId()), String.valueOf(attachment.getAttachmentId())});
-  }
-
-  private static void processSticker(@NonNull Context context, @NonNull AttachmentSecret attachmentSecret, @NonNull SQLiteDatabase db, @NonNull Sticker sticker, BackupRecordInputStream inputStream)
-      throws IOException
-  {
-    File stickerDirectory = context.getDir(AttachmentDatabase.DIRECTORY, Context.MODE_PRIVATE);
-    File dataFile         = File.createTempFile("sticker", ".mms", stickerDirectory);
-
-    Pair<byte[], OutputStream> output = ModernEncryptingPartOutputStream.createFor(attachmentSecret, dataFile, false);
-
-    inputStream.readAttachmentTo(output.second, sticker.getLength());
-
-    ContentValues contentValues = new ContentValues();
-    contentValues.put(StickerDatabase.FILE_PATH, dataFile.getAbsolutePath());
-    contentValues.put(StickerDatabase.FILE_RANDOM, output.first);
-
-    db.update(StickerDatabase.TABLE_NAME, contentValues,
-              StickerDatabase._ID + " = ?",
-              new String[] {String.valueOf(sticker.getRowId())});
-  }
-
-  private static void processAvatar(@NonNull Context context, @NonNull BackupProtos.Avatar avatar, @NonNull BackupRecordInputStream inputStream) throws IOException {
-    inputStream.readAttachmentTo(new FileOutputStream(AvatarHelper.getAvatarFile(context, Address.fromExternal(context, avatar.getName()))), avatar.getLength());
-  }
-
-  @SuppressLint("ApplySharedPref")
-  private static void processPreference(@NonNull Context context, SharedPreference preference) {
-    SharedPreferences preferences = context.getSharedPreferences(preference.getFile(), 0);
-    preferences.edit().putString(preference.getKey(), preference.getValue()).commit();
-  }
-
-  private static void dropAllTables(@NonNull SQLiteDatabase db) {
-    try (Cursor cursor = db.rawQuery("SELECT name, type FROM sqlite_master", null)) {
-      while (cursor != null && cursor.moveToNext()) {
-        String name = cursor.getString(0);
-        String type = cursor.getString(1);
-
-        if ("table".equals(type) && !name.startsWith("sqlite_")) {
-          db.execSQL("DROP TABLE IF EXISTS " + name);
-        }
-      }
-    }
-  }
-
-  private static void trimEntriesForExpiredMessages(@NonNull Context context, @NonNull SQLiteDatabase db) {
-    String trimmedCondition = " NOT IN (SELECT " + MmsDatabase.ID + " FROM " + MmsDatabase.TABLE_NAME + ")";
-
-    db.delete(GroupReceiptDatabase.TABLE_NAME, GroupReceiptDatabase.MMS_ID + trimmedCondition, null);
-
-    String[] columns = new String[] { AttachmentDatabase.ROW_ID, AttachmentDatabase.UNIQUE_ID };
-    String   where   = AttachmentDatabase.MMS_ID + trimmedCondition;
-
-    try (Cursor cursor = db.query(AttachmentDatabase.TABLE_NAME, columns, where, null, null, null, null)) {
-      while (cursor != null && cursor.moveToNext()) {
-        DatabaseFactory.getAttachmentDatabase(context).deleteAttachment(new AttachmentId(cursor.getLong(0), cursor.getLong(1)));
-      }
-    }
-
-    try (Cursor cursor = db.query(ThreadDatabase.TABLE_NAME, new String[] { ThreadDatabase.ID }, ThreadDatabase.EXPIRES_IN + " > 0", null, null, null, null)) {
-      while (cursor != null && cursor.moveToNext()) {
-        DatabaseFactory.getThreadDatabase(context).update(cursor.getLong(0), false);
-      }
-    }
-  }
-
-
-  private static class BackupRecordInputStream extends BackupStream {
-
-    private final InputStream in;
-    private final Cipher      cipher;
-    private final Mac         mac;
-
-    private final byte[] cipherKey;
-    private final byte[] macKey;
-
-    private byte[] iv;
-    private int    counter;
-
-    private BackupRecordInputStream(@NonNull File file, @NonNull String passphrase) throws IOException {
-      try {
-        this.in     = new FileInputStream(file);
-
-        byte[] headerLengthBytes = new byte[4];
-        Util.readFully(in, headerLengthBytes);
-
-        int headerLength = Conversions.byteArrayToInt(headerLengthBytes);
-        byte[] headerFrame = new byte[headerLength];
-        Util.readFully(in, headerFrame);
-
-        BackupFrame frame = BackupFrame.parseFrom(headerFrame);
-
-        if (!frame.hasHeader()) {
-          throw new IOException("Backup stream does not start with header!");
-        }
-
-        BackupProtos.Header header = frame.getHeader();
-
-        this.iv = header.getIv().toByteArray();
-
-        if (iv.length != 16) {
-          throw new IOException("Invalid IV length!");
-        }
-
-        byte[]   key     = getBackupKey(passphrase, header.hasSalt() ? header.getSalt().toByteArray() : null);
-        byte[]   derived = new HKDFv3().deriveSecrets(key, "Backup Export".getBytes(), 64);
-        byte[][] split   = ByteUtil.split(derived, 32, 32);
-
-        this.cipherKey = split[0];
-        this.macKey    = split[1];
-
-        this.cipher = Cipher.getInstance("AES/CTR/NoPadding");
-        this.mac    = Mac.getInstance("HmacSHA256");
-        this.mac.init(new SecretKeySpec(macKey, "HmacSHA256"));
-
-        this.counter = Conversions.byteArrayToInt(iv);
-      } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException e) {
-        throw new AssertionError(e);
-      }
-    }
-
-    BackupFrame readFrame() throws IOException {
-      return readFrame(in);
-    }
-
-    void readAttachmentTo(OutputStream out, int length) throws IOException {
-      try {
-        Conversions.intToByteArray(iv, 0, counter++);
-        cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(cipherKey, "AES"), new IvParameterSpec(iv));
-        mac.update(iv);
-
-        byte[] buffer = new byte[8192];
-
-        while (length > 0) {
-          int read = in.read(buffer, 0, Math.min(buffer.length, length));
-          if (read == -1) throw new IOException("File ended early!");
-
-          mac.update(buffer, 0, read);
-
-          byte[] plaintext = cipher.update(buffer, 0, read);
-
-          if (plaintext != null) {
-            out.write(plaintext, 0, plaintext.length);
-          }
-
-          length -= read;
-        }
-
-        byte[] plaintext = cipher.doFinal();
-
-        if (plaintext != null) {
-          out.write(plaintext, 0, plaintext.length);
-        }
-
-        out.close();
-
-        byte[] ourMac   = ByteUtil.trim(mac.doFinal(), 10);
-        byte[] theirMac = new byte[10];
-
-        try {
-          Util.readFully(in, theirMac);
-        } catch (IOException e) {
-          //destination.delete();
-          throw new IOException(e);
-        }
-
-        if (!MessageDigest.isEqual(ourMac, theirMac)) {
-          //destination.delete();
-          throw new IOException("Bad MAC");
-        }
-      } catch (InvalidKeyException | InvalidAlgorithmParameterException | IllegalBlockSizeException | BadPaddingException e) {
-        throw new AssertionError(e);
-      }
-    }
-
-    private BackupFrame readFrame(InputStream in) throws IOException {
-      try {
-        byte[] length = new byte[4];
-        Util.readFully(in, length);
-
-        byte[] frame = new byte[Conversions.byteArrayToInt(length)];
-        Util.readFully(in, frame);
-
-        byte[] theirMac = new byte[10];
-        System.arraycopy(frame, frame.length - 10, theirMac, 0, theirMac.length);
-
-        mac.update(frame, 0, frame.length - 10);
-        byte[] ourMac = ByteUtil.trim(mac.doFinal(), 10);
-
-        if (!MessageDigest.isEqual(ourMac, theirMac)) {
-          throw new IOException("Bad MAC");
-        }
-
-        Conversions.intToByteArray(iv, 0, counter++);
-        cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(cipherKey, "AES"), new IvParameterSpec(iv));
-
-        byte[] plaintext = cipher.doFinal(frame, 0, frame.length - 10);
-
-        return BackupFrame.parseFrom(plaintext);
-      } catch (InvalidKeyException | InvalidAlgorithmParameterException | IllegalBlockSizeException | BadPaddingException e) {
-        throw new AssertionError(e);
-      }
-    }
-  }
-
-  public static class DatabaseDowngradeException extends IOException {
-    DatabaseDowngradeException(int currentVersion, int backupVersion) {
-      super("Tried to import a backup with version " + backupVersion + " into a database with version " + currentVersion);
-    }
-  }
-}
diff --git a/src/org/thoughtcrime/securesms/backup/FullBackupImporter.kt b/src/org/thoughtcrime/securesms/backup/FullBackupImporter.kt
new file mode 100644
index 0000000000..03b576d1da
--- /dev/null
+++ b/src/org/thoughtcrime/securesms/backup/FullBackupImporter.kt
@@ -0,0 +1,346 @@
+package org.thoughtcrime.securesms.backup
+
+import android.annotation.SuppressLint
+import android.content.ContentValues
+import android.content.Context
+import android.net.Uri
+import androidx.annotation.WorkerThread
+import net.sqlcipher.database.SQLiteDatabase
+import org.greenrobot.eventbus.EventBus
+import org.thoughtcrime.securesms.attachments.AttachmentId
+import org.thoughtcrime.securesms.backup.BackupProtos.*
+import org.thoughtcrime.securesms.crypto.AttachmentSecret
+import org.thoughtcrime.securesms.crypto.ModernEncryptingPartOutputStream
+import org.thoughtcrime.securesms.database.*
+import org.thoughtcrime.securesms.logging.Log
+import org.thoughtcrime.securesms.profiles.AvatarHelper
+import org.thoughtcrime.securesms.util.BackupUtil
+import org.thoughtcrime.securesms.util.Conversions
+import org.thoughtcrime.securesms.util.Util
+import org.whispersystems.libsignal.kdf.HKDFv3
+import org.whispersystems.libsignal.util.ByteUtil
+import java.io.*
+import java.security.InvalidAlgorithmParameterException
+import java.security.InvalidKeyException
+import java.security.MessageDigest
+import java.security.NoSuchAlgorithmException
+import java.util.*
+import javax.crypto.*
+import javax.crypto.spec.IvParameterSpec
+import javax.crypto.spec.SecretKeySpec
+
+object FullBackupImporter {
+    /**
+     * Because BackupProtos.SharedPreference was made only to serialize string values,
+     * we use these 3-char prefixes to explicitly cast the values before inserting to a preference file.
+     */
+    const val PREF_PREFIX_TYPE_INT = "i__"
+    const val PREF_PREFIX_TYPE_BOOLEAN = "b__"
+
+    private val TAG = FullBackupImporter::class.java.simpleName
+
+    @JvmStatic
+    @WorkerThread
+    @Throws(IOException::class)
+    fun importFromUri(context: Context,
+                      attachmentSecret: AttachmentSecret,
+                      db: SQLiteDatabase,
+                      fileUri: Uri,
+                      passphrase: String) {
+
+        val baseInputStream = context.contentResolver.openInputStream(fileUri)
+                ?: throw IOException("Cannot open an input stream for the file URI: $fileUri")
+
+        var count = 0
+        try {
+            BackupRecordInputStream(baseInputStream, passphrase).use { inputStream ->
+                db.beginTransaction()
+                dropAllTables(db)
+                var frame: BackupFrame
+                while (!inputStream.readFrame().also { frame = it }.end) {
+                    if (count++ % 100 == 0) EventBus.getDefault().post(BackupEvent.createProgress(count))
+                    when {
+                        frame.hasVersion() -> processVersion(db, frame.version)
+                        frame.hasStatement() -> processStatement(db, frame.statement)
+                        frame.hasPreference() -> processPreference(context, frame.preference)
+                        frame.hasAttachment() -> processAttachment(context, attachmentSecret, db, frame.attachment, inputStream)
+                        frame.hasSticker() -> processSticker(context, attachmentSecret, db, frame.sticker, inputStream)
+                        frame.hasAvatar() -> processAvatar(context, frame.avatar, inputStream)
+                    }
+                }
+                trimEntriesForExpiredMessages(context, db)
+                db.setTransactionSuccessful()
+            }
+        } finally {
+            if (db.inTransaction()) {
+                db.endTransaction()
+            }
+        }
+        EventBus.getDefault().post(BackupEvent.createFinished())
+    }
+
+    @Throws(IOException::class)
+    private fun processVersion(db: SQLiteDatabase, version: DatabaseVersion) {
+        if (version.version > db.version) {
+            throw DatabaseDowngradeException(db.version, version.version)
+        }
+        db.version = version.version
+    }
+
+    private fun processStatement(db: SQLiteDatabase, statement: SqlStatement) {
+        val isForSmsFtsSecretTable = statement.statement.contains(SearchDatabase.SMS_FTS_TABLE_NAME + "_")
+        val isForMmsFtsSecretTable = statement.statement.contains(SearchDatabase.MMS_FTS_TABLE_NAME + "_")
+        val isForSqliteSecretTable = statement.statement.toLowerCase(Locale.ENGLISH).startsWith("create table sqlite_")
+        if (isForSmsFtsSecretTable || isForMmsFtsSecretTable || isForSqliteSecretTable) {
+            Log.i(TAG, "Ignoring import for statement: " + statement.statement)
+            return
+        }
+        val parameters: MutableList<Any?> = LinkedList()
+        for (parameter in statement.parametersList) {
+            when {
+                parameter.hasStringParamter() -> parameters.add(parameter.stringParamter)
+                parameter.hasDoubleParameter() -> parameters.add(parameter.doubleParameter)
+                parameter.hasIntegerParameter() -> parameters.add(parameter.integerParameter)
+                parameter.hasBlobParameter() -> parameters.add(parameter.blobParameter.toByteArray())
+                parameter.hasNullparameter() -> parameters.add(null)
+            }
+        }
+        if (parameters.size > 0) {
+            db.execSQL(statement.statement, parameters.toTypedArray())
+        } else {
+            db.execSQL(statement.statement)
+        }
+    }
+
+    @Throws(IOException::class)
+    private fun processAttachment(context: Context, attachmentSecret: AttachmentSecret,
+                                  db: SQLiteDatabase, attachment: Attachment,
+                                  inputStream: BackupRecordInputStream) {
+        val partsDirectory = context.getDir(AttachmentDatabase.DIRECTORY, Context.MODE_PRIVATE)
+        val dataFile = File.createTempFile("part", ".mms", partsDirectory)
+        val output = ModernEncryptingPartOutputStream.createFor(attachmentSecret, dataFile, false)
+        inputStream.readAttachmentTo(output.second, attachment.length)
+        val contentValues = ContentValues()
+        contentValues.put(AttachmentDatabase.DATA, dataFile.absolutePath)
+        contentValues.put(AttachmentDatabase.THUMBNAIL, null as String?)
+        contentValues.put(AttachmentDatabase.DATA_RANDOM, output.first)
+        db.update(AttachmentDatabase.TABLE_NAME, contentValues,
+                "${AttachmentDatabase.ROW_ID} = ? AND ${AttachmentDatabase.UNIQUE_ID} = ?",
+                arrayOf(attachment.rowId.toString(), attachment.attachmentId.toString()))
+    }
+
+    @Throws(IOException::class)
+    private fun processSticker(context: Context, attachmentSecret: AttachmentSecret,
+                               db: SQLiteDatabase, sticker: Sticker,
+                               inputStream: BackupRecordInputStream) {
+        val stickerDirectory = context.getDir(AttachmentDatabase.DIRECTORY, Context.MODE_PRIVATE)
+        val dataFile = File.createTempFile("sticker", ".mms", stickerDirectory)
+        val output = ModernEncryptingPartOutputStream.createFor(attachmentSecret, dataFile, false)
+        inputStream.readAttachmentTo(output.second, sticker.length)
+        val contentValues = ContentValues()
+        contentValues.put(StickerDatabase.FILE_PATH, dataFile.absolutePath)
+        contentValues.put(StickerDatabase.FILE_RANDOM, output.first)
+        db.update(StickerDatabase.TABLE_NAME, contentValues,
+                StickerDatabase._ID + " = ?", arrayOf(sticker.rowId.toString()))
+    }
+
+    @Throws(IOException::class)
+    private fun processAvatar(context: Context, avatar: Avatar, inputStream: BackupRecordInputStream) {
+        inputStream.readAttachmentTo(FileOutputStream(
+                AvatarHelper.getAvatarFile(context, Address.fromExternal(context, avatar.name))), avatar.length)
+    }
+
+    @SuppressLint("ApplySharedPref")
+    private fun processPreference(context: Context, preference: SharedPreference) {
+        val preferences = context.getSharedPreferences(preference.file, 0)
+        val key = preference.key
+        val value = preference.value
+
+        // See the comment next to PREF_PREFIX_TYPE_* constants.
+        when {
+            key.startsWith(PREF_PREFIX_TYPE_INT) ->
+                preferences.edit().putInt(
+                        key.substring(PREF_PREFIX_TYPE_INT.length),
+                        value.toInt()
+                ).commit()
+            key.startsWith(PREF_PREFIX_TYPE_BOOLEAN) ->
+                preferences.edit().putBoolean(
+                        key.substring(PREF_PREFIX_TYPE_BOOLEAN.length),
+                        value.toBoolean()
+                ).commit()
+            else ->
+                preferences.edit().putString(key, value).commit()
+        }
+    }
+
+    private fun dropAllTables(db: SQLiteDatabase) {
+        db.rawQuery("SELECT name, type FROM sqlite_master", null).use { cursor ->
+            while (cursor != null && cursor.moveToNext()) {
+                val name = cursor.getString(0)
+                val type = cursor.getString(1)
+                if ("table" == type && !name.startsWith("sqlite_")) {
+                    db.execSQL("DROP TABLE IF EXISTS $name")
+                }
+            }
+        }
+    }
+
+    private fun trimEntriesForExpiredMessages(context: Context, db: SQLiteDatabase) {
+        val trimmedCondition = " NOT IN (SELECT ${MmsDatabase.ID} FROM ${MmsDatabase.TABLE_NAME})"
+        db.delete(GroupReceiptDatabase.TABLE_NAME, GroupReceiptDatabase.MMS_ID + trimmedCondition, null)
+        val columns = arrayOf(AttachmentDatabase.ROW_ID, AttachmentDatabase.UNIQUE_ID)
+        val where = AttachmentDatabase.MMS_ID + trimmedCondition
+        db.query(AttachmentDatabase.TABLE_NAME, columns, where, null, null, null, null).use { cursor ->
+            while (cursor != null && cursor.moveToNext()) {
+                DatabaseFactory.getAttachmentDatabase(context)
+                        .deleteAttachment(AttachmentId(cursor.getLong(0), cursor.getLong(1)))
+            }
+        }
+        db.query(ThreadDatabase.TABLE_NAME, arrayOf(ThreadDatabase.ID),
+                ThreadDatabase.EXPIRES_IN + " > 0", null, null, null, null).use { cursor ->
+            while (cursor != null && cursor.moveToNext()) {
+                DatabaseFactory.getThreadDatabase(context).update(cursor.getLong(0), false)
+            }
+        }
+    }
+
+    private class BackupRecordInputStream : Closeable {
+        private val inputStream: InputStream
+        private val cipher: Cipher
+        private val mac: Mac
+        private val cipherKey: ByteArray
+        private val macKey: ByteArray
+        private val iv: ByteArray
+
+        private var counter = 0
+
+        @Throws(IOException::class)
+        constructor(inputStream: InputStream, passphrase: String) : super() {
+            try {
+                this.inputStream = inputStream
+                val headerLengthBytes = ByteArray(4)
+                Util.readFully(this.inputStream, headerLengthBytes)
+                val headerLength = Conversions.byteArrayToInt(headerLengthBytes)
+                val headerFrame = ByteArray(headerLength)
+                Util.readFully(this.inputStream, headerFrame)
+                val frame = BackupFrame.parseFrom(headerFrame)
+                if (!frame.hasHeader()) {
+                    throw IOException("Backup stream does not start with header!")
+                }
+                val header = frame.header
+                iv = header.iv.toByteArray()
+                if (iv.size != 16) {
+                    throw IOException("Invalid IV length!")
+                }
+                val key = BackupUtil.computeBackupKey(passphrase, if (header.hasSalt()) header.salt.toByteArray() else null)
+                val derived = HKDFv3().deriveSecrets(key, "Backup Export".toByteArray(), 64)
+                val split = ByteUtil.split(derived, 32, 32)
+                cipherKey = split[0]
+                macKey = split[1]
+                cipher = Cipher.getInstance("AES/CTR/NoPadding")
+                mac = Mac.getInstance("HmacSHA256")
+                mac.init(SecretKeySpec(macKey, "HmacSHA256"))
+                counter = Conversions.byteArrayToInt(iv)
+            } catch (e: Exception) {
+                when (e) {
+                    is NoSuchAlgorithmException,
+                    is NoSuchPaddingException,
+                    is InvalidKeyException -> {
+                        throw AssertionError(e)
+                    }
+                    else -> throw e
+                }
+            }
+        }
+
+        @Throws(IOException::class)
+        fun readFrame(): BackupFrame {
+            return readFrame(inputStream)
+        }
+
+        @Throws(IOException::class)
+        fun readAttachmentTo(out: OutputStream, length: Int) {
+            var length = length
+            try {
+                Conversions.intToByteArray(iv, 0, counter++)
+                cipher.init(Cipher.DECRYPT_MODE, SecretKeySpec(cipherKey, "AES"), IvParameterSpec(iv))
+                mac.update(iv)
+                val buffer = ByteArray(8192)
+                while (length > 0) {
+                    val read = inputStream.read(buffer, 0, Math.min(buffer.size, length))
+                    if (read == -1) throw IOException("File ended early!")
+                    mac.update(buffer, 0, read)
+                    val plaintext = cipher.update(buffer, 0, read)
+                    if (plaintext != null) {
+                        out.write(plaintext, 0, plaintext.size)
+                    }
+                    length -= read
+                }
+                val plaintext = cipher.doFinal()
+                if (plaintext != null) {
+                    out.write(plaintext, 0, plaintext.size)
+                }
+                out.close()
+                val ourMac = ByteUtil.trim(mac.doFinal(), 10)
+                val theirMac = ByteArray(10)
+                try {
+                    Util.readFully(inputStream, theirMac)
+                } catch (e: IOException) {
+                    throw IOException(e)
+                }
+                if (!MessageDigest.isEqual(ourMac, theirMac)) {
+                    throw IOException("Bad MAC")
+                }
+            } catch (e: Exception) {
+                when (e) {
+                    is InvalidKeyException,
+                    is InvalidAlgorithmParameterException,
+                    is IllegalBlockSizeException,
+                    is BadPaddingException -> {
+                        throw AssertionError(e)
+                    }
+                    else -> throw e
+                }
+            }
+        }
+
+        @Throws(IOException::class)
+        private fun readFrame(`in`: InputStream?): BackupFrame {
+            return try {
+                val length = ByteArray(4)
+                Util.readFully(`in`, length)
+                val frame = ByteArray(Conversions.byteArrayToInt(length))
+                Util.readFully(`in`, frame)
+                val theirMac = ByteArray(10)
+                System.arraycopy(frame, frame.size - 10, theirMac, 0, theirMac.size)
+                mac.update(frame, 0, frame.size - 10)
+                val ourMac = ByteUtil.trim(mac.doFinal(), 10)
+                if (!MessageDigest.isEqual(ourMac, theirMac)) {
+                    throw IOException("Bad MAC")
+                }
+                Conversions.intToByteArray(iv, 0, counter++)
+                cipher.init(Cipher.DECRYPT_MODE, SecretKeySpec(cipherKey, "AES"), IvParameterSpec(iv))
+                val plaintext = cipher.doFinal(frame, 0, frame.size - 10)
+                BackupFrame.parseFrom(plaintext)
+            } catch (e: Exception) {
+                when (e) {
+                    is InvalidKeyException,
+                    is InvalidAlgorithmParameterException,
+                    is IllegalBlockSizeException,
+                    is BadPaddingException -> {
+                        throw AssertionError(e)
+                    }
+                    else -> throw e
+                }
+            }
+        }
+
+        @Throws(IOException::class)
+        override fun close() {
+            inputStream.close()
+        }
+    }
+
+    class DatabaseDowngradeException internal constructor(currentVersion: Int, backupVersion: Int) :
+            IOException("Tried to import a backup with version $backupVersion into a database with version $currentVersion")
+}
\ No newline at end of file
diff --git a/src/org/thoughtcrime/securesms/conversation/ConversationFragment.java b/src/org/thoughtcrime/securesms/conversation/ConversationFragment.java
index e8a766f0e4..d260dcb0c6 100644
--- a/src/org/thoughtcrime/securesms/conversation/ConversationFragment.java
+++ b/src/org/thoughtcrime/securesms/conversation/ConversationFragment.java
@@ -548,12 +548,12 @@ public class ConversationFragment extends Fragment
                       }
                     } else if (!ignoredMessages.contains(serverID)) {
                       failedMessages.add(messageRecord.getId());
-                      Log.d("Loki", "Failed to delete message: " + messageRecord.getId() + ".");
+                      Log.w("Loki", "Failed to delete message: " + messageRecord.getId() + ".");
                     }
                   }
                   return null;
                 }). fail(e -> {
-                  Log.d("Loki", "Couldn't delete message due to error: " + e.toString() + ".");
+                  Log.w("Loki", "Couldn't delete message due to error: " + e.toString() + ".");
                   return null;
                 });
               }
diff --git a/src/org/thoughtcrime/securesms/crypto/IdentityKeyUtil.java b/src/org/thoughtcrime/securesms/crypto/IdentityKeyUtil.java
index 9d3877fc75..80306b4ed5 100644
--- a/src/org/thoughtcrime/securesms/crypto/IdentityKeyUtil.java
+++ b/src/org/thoughtcrime/securesms/crypto/IdentityKeyUtil.java
@@ -122,21 +122,42 @@ public class IdentityKeyUtil {
     }
   }
 
-  public static List<BackupProtos.SharedPreference> getBackupRecord(@NonNull Context context) {
+  public static List<BackupProtos.SharedPreference> getBackupRecords(@NonNull Context context) {
     SharedPreferences preferences = context.getSharedPreferences(MasterSecretUtil.PREFERENCES_NAME, 0);
 
-    return new LinkedList<BackupProtos.SharedPreference>() {{
-      add(BackupProtos.SharedPreference.newBuilder()
-                                       .setFile(MasterSecretUtil.PREFERENCES_NAME)
-                                       .setKey(IDENTITY_PUBLIC_KEY_PREF)
-                                       .setValue(preferences.getString(IDENTITY_PUBLIC_KEY_PREF, null))
-                                       .build());
-      add(BackupProtos.SharedPreference.newBuilder()
-                                       .setFile(MasterSecretUtil.PREFERENCES_NAME)
-                                       .setKey(IDENTITY_PRIVATE_KEY_PREF)
-                                       .setValue(preferences.getString(IDENTITY_PRIVATE_KEY_PREF, null))
-                                       .build());
-    }};
+    LinkedList<BackupProtos.SharedPreference> prefList = new LinkedList<>();
+
+    prefList.add(BackupProtos.SharedPreference.newBuilder()
+            .setFile(MasterSecretUtil.PREFERENCES_NAME)
+            .setKey(IDENTITY_PUBLIC_KEY_PREF)
+            .setValue(preferences.getString(IDENTITY_PUBLIC_KEY_PREF, null))
+            .build());
+    prefList.add(BackupProtos.SharedPreference.newBuilder()
+            .setFile(MasterSecretUtil.PREFERENCES_NAME)
+            .setKey(IDENTITY_PRIVATE_KEY_PREF)
+            .setValue(preferences.getString(IDENTITY_PRIVATE_KEY_PREF, null))
+            .build());
+    if (preferences.contains(ED25519_PUBLIC_KEY)) {
+      prefList.add(BackupProtos.SharedPreference.newBuilder()
+              .setFile(MasterSecretUtil.PREFERENCES_NAME)
+              .setKey(ED25519_PUBLIC_KEY)
+              .setValue(preferences.getString(ED25519_PUBLIC_KEY, null))
+              .build());
+    }
+    if (preferences.contains(ED25519_SECRET_KEY)) {
+      prefList.add(BackupProtos.SharedPreference.newBuilder()
+              .setFile(MasterSecretUtil.PREFERENCES_NAME)
+              .setKey(ED25519_SECRET_KEY)
+              .setValue(preferences.getString(ED25519_SECRET_KEY, null))
+              .build());
+    }
+    prefList.add(BackupProtos.SharedPreference.newBuilder()
+            .setFile(MasterSecretUtil.PREFERENCES_NAME)
+            .setKey(LOKI_SEED)
+            .setValue(preferences.getString(LOKI_SEED, null))
+            .build());
+
+    return prefList;
   }
 
   private static boolean hasLegacyIdentityKeys(Context context) {
diff --git a/src/org/thoughtcrime/securesms/database/DraftDatabase.java b/src/org/thoughtcrime/securesms/database/DraftDatabase.java
index 27435bfc1e..b5aa0dd5c9 100644
--- a/src/org/thoughtcrime/securesms/database/DraftDatabase.java
+++ b/src/org/thoughtcrime/securesms/database/DraftDatabase.java
@@ -17,11 +17,11 @@ import java.util.Set;
 
 public class DraftDatabase extends Database {
 
-  private static final String TABLE_NAME  = "drafts";
-  public  static final String ID          = "_id";
-  public  static final String THREAD_ID   = "thread_id";
-  public  static final String DRAFT_TYPE  = "type";
-  public  static final String DRAFT_VALUE = "value";
+  public static final String TABLE_NAME  = "drafts";
+  public static final String ID          = "_id";
+  public static final String THREAD_ID   = "thread_id";
+  public static final String DRAFT_TYPE  = "type";
+  public static final String DRAFT_VALUE = "value";
 
   public static final String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME + " (" + ID + " INTEGER PRIMARY KEY, " +
                                             THREAD_ID + " INTEGER, " + DRAFT_TYPE + " TEXT, " + DRAFT_VALUE + " TEXT);";
diff --git a/src/org/thoughtcrime/securesms/database/JobDatabase.java b/src/org/thoughtcrime/securesms/database/JobDatabase.java
index 1a64eed210..f878e3061a 100644
--- a/src/org/thoughtcrime/securesms/database/JobDatabase.java
+++ b/src/org/thoughtcrime/securesms/database/JobDatabase.java
@@ -22,8 +22,8 @@ public class JobDatabase extends Database {
                                                              Constraints.CREATE_TABLE,
                                                              Dependencies.CREATE_TABLE };
 
-  private static final class Jobs {
-    private static final String TABLE_NAME            = "job_spec";
+  public static final class Jobs {
+    public  static final String TABLE_NAME            = "job_spec";
     private static final String ID                    = "_id";
     private static final String JOB_SPEC_ID           = "job_spec_id";
     private static final String FACTORY_KEY           = "factory_key";
@@ -53,8 +53,8 @@ public class JobDatabase extends Database {
                                                                                     IS_RUNNING            + " INTEGER)";
   }
 
-  private static final class Constraints {
-    private static final String TABLE_NAME  = "constraint_spec";
+  public static final class Constraints {
+    public  static final String TABLE_NAME  = "constraint_spec";
     private static final String ID          = "_id";
     private static final String JOB_SPEC_ID = "job_spec_id";
     private static final String FACTORY_KEY = "factory_key";
@@ -65,8 +65,8 @@ public class JobDatabase extends Database {
                                                                                     "UNIQUE(" + JOB_SPEC_ID + ", " + FACTORY_KEY + "))";
   }
 
-  private static final class Dependencies {
-    private static final String TABLE_NAME             = "dependency_spec";
+  public static final class Dependencies {
+    public  static final String TABLE_NAME             = "dependency_spec";
     private static final String ID                     = "_id";
     private static final String JOB_SPEC_ID            = "job_spec_id";
     private static final String DEPENDS_ON_JOB_SPEC_ID = "depends_on_job_spec_id";
diff --git a/src/org/thoughtcrime/securesms/database/PushDatabase.java b/src/org/thoughtcrime/securesms/database/PushDatabase.java
index 55472f3117..4864b37e76 100644
--- a/src/org/thoughtcrime/securesms/database/PushDatabase.java
+++ b/src/org/thoughtcrime/securesms/database/PushDatabase.java
@@ -20,16 +20,16 @@ public class PushDatabase extends Database {
 
   private static final String TAG = PushDatabase.class.getSimpleName();
 
-  private static final String TABLE_NAME       = "push";
-  public  static final String ID               = "_id";
-  public  static final String TYPE             = "type";
-  public  static final String SOURCE           = "source";
-  public  static final String DEVICE_ID        = "device_id";
-  public  static final String LEGACY_MSG       = "body";
-  public  static final String CONTENT          = "content";
-  public  static final String TIMESTAMP        = "timestamp";
-  public  static final String SERVER_TIMESTAMP = "server_timestamp";
-  public  static final String SERVER_GUID      = "server_guid";
+  public static final String TABLE_NAME       = "push";
+  public static final String ID               = "_id";
+  public static final String TYPE             = "type";
+  public static final String SOURCE           = "source";
+  public static final String DEVICE_ID        = "device_id";
+  public static final String LEGACY_MSG       = "body";
+  public static final String CONTENT          = "content";
+  public static final String TIMESTAMP        = "timestamp";
+  public static final String SERVER_TIMESTAMP = "server_timestamp";
+  public static final String SERVER_GUID      = "server_guid";
 
   public static final String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME + " (" + ID + " INTEGER PRIMARY KEY, " +
       TYPE + " INTEGER, " + SOURCE + " TEXT, " + DEVICE_ID + " INTEGER, " + LEGACY_MSG + " TEXT, " + CONTENT + " TEXT, " + TIMESTAMP + " INTEGER, " +
diff --git a/src/org/thoughtcrime/securesms/database/ThreadDatabase.java b/src/org/thoughtcrime/securesms/database/ThreadDatabase.java
index 20d822f8ac..e17d484681 100644
--- a/src/org/thoughtcrime/securesms/database/ThreadDatabase.java
+++ b/src/org/thoughtcrime/securesms/database/ThreadDatabase.java
@@ -50,12 +50,15 @@ import org.whispersystems.libsignal.util.Pair;
 import org.whispersystems.libsignal.util.guava.Optional;
 
 import java.io.Closeable;
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
+import nl.komponents.kovenant.combine.Tuple2;
+
 public class ThreadDatabase extends Database {
 
   private static final String TAG = ThreadDatabase.class.getSimpleName();
@@ -618,6 +621,34 @@ public class ThreadDatabase extends Database {
     }
   }
 
+  /**
+   * A lightweight utility method to retrieve the complete list of non-archived threads coupled with their recipient address.
+   * @return a tuple with non-null values: thread id, recipient address.
+   */
+  public @NonNull List<Tuple2<Long, String>> getConversationListQuick() {
+    SQLiteDatabase db = databaseHelper.getReadableDatabase();
+
+    ArrayList<Tuple2<Long, String>> result = new ArrayList<>();
+
+    try (Cursor cursor = db.query(
+            TABLE_NAME,
+            new String[]{ID, ADDRESS},
+            ARCHIVED + " = 0 AND " + MESSAGE_COUNT + " != 0 AND " + ADDRESS + " IS NOT NULL",
+            null,
+            null,
+            null,
+            null)) {
+      while (cursor != null && cursor.moveToNext()) {
+        result.add(new Tuple2<>(
+                cursor.getLong(cursor.getColumnIndexOrThrow(ID)),
+                cursor.getString(cursor.getColumnIndexOrThrow(ADDRESS))
+        ));
+      }
+    }
+
+    return result;
+  }
+
   private @NonNull String getFormattedBodyFor(@NonNull MessageRecord messageRecord) {
     if (messageRecord.isMms()) {
       MmsMessageRecord record = (MmsMessageRecord) messageRecord;
diff --git a/src/org/thoughtcrime/securesms/jobmanager/migration/WorkManagerFactoryMappings.java b/src/org/thoughtcrime/securesms/jobmanager/migration/WorkManagerFactoryMappings.java
index 0ef55f60fc..b6c05d95ed 100644
--- a/src/org/thoughtcrime/securesms/jobmanager/migration/WorkManagerFactoryMappings.java
+++ b/src/org/thoughtcrime/securesms/jobmanager/migration/WorkManagerFactoryMappings.java
@@ -45,6 +45,7 @@ import org.thoughtcrime.securesms.jobs.TrimThreadJob;
 import org.thoughtcrime.securesms.jobs.TypingSendJob;
 import org.thoughtcrime.securesms.jobs.UpdateApkJob;
 import org.thoughtcrime.securesms.loki.api.PrepareAttachmentAudioExtrasJob;
+import org.thoughtcrime.securesms.loki.api.ResetThreadSessionJob;
 import org.thoughtcrime.securesms.loki.protocol.ClosedGroupUpdateMessageSendJob;
 import org.thoughtcrime.securesms.loki.protocol.NullMessageSendJob;
 import org.thoughtcrime.securesms.loki.protocol.SessionRequestMessageSendJob;
@@ -102,6 +103,7 @@ public class WorkManagerFactoryMappings {
     put(TypingSendJob.class.getName(), TypingSendJob.KEY);
     put(UpdateApkJob.class.getName(), UpdateApkJob.KEY);
     put(PrepareAttachmentAudioExtrasJob.class.getName(), PrepareAttachmentAudioExtrasJob.KEY);
+    put(ResetThreadSessionJob.class.getName(), ResetThreadSessionJob.KEY);
   }};
 
   public static @Nullable String getFactoryKey(@NonNull String workManagerClass) {
diff --git a/src/org/thoughtcrime/securesms/jobs/JobManagerFactories.java b/src/org/thoughtcrime/securesms/jobs/JobManagerFactories.java
index 82dbf831f7..e6f63503df 100644
--- a/src/org/thoughtcrime/securesms/jobs/JobManagerFactories.java
+++ b/src/org/thoughtcrime/securesms/jobs/JobManagerFactories.java
@@ -15,6 +15,7 @@ import org.thoughtcrime.securesms.jobmanager.impl.NetworkOrCellServiceConstraint
 import org.thoughtcrime.securesms.jobmanager.impl.SqlCipherMigrationConstraint;
 import org.thoughtcrime.securesms.jobmanager.impl.SqlCipherMigrationConstraintObserver;
 import org.thoughtcrime.securesms.loki.api.PrepareAttachmentAudioExtrasJob;
+import org.thoughtcrime.securesms.loki.api.ResetThreadSessionJob;
 import org.thoughtcrime.securesms.loki.protocol.ClosedGroupUpdateMessageSendJob;
 import org.thoughtcrime.securesms.loki.protocol.NullMessageSendJob;
 import org.thoughtcrime.securesms.loki.protocol.SessionRequestMessageSendJob;
@@ -79,6 +80,7 @@ public final class JobManagerFactories {
       put(TypingSendJob.KEY,                         new TypingSendJob.Factory());
       put(UpdateApkJob.KEY,                          new UpdateApkJob.Factory());
       put(PrepareAttachmentAudioExtrasJob.KEY,       new PrepareAttachmentAudioExtrasJob.Factory());
+      put(ResetThreadSessionJob.KEY,                 new ResetThreadSessionJob.Factory());
     }};
   }
 
diff --git a/src/org/thoughtcrime/securesms/jobs/LocalBackupJob.java b/src/org/thoughtcrime/securesms/jobs/LocalBackupJob.java
index 3e378a1fb5..604a2f1548 100644
--- a/src/org/thoughtcrime/securesms/jobs/LocalBackupJob.java
+++ b/src/org/thoughtcrime/securesms/jobs/LocalBackupJob.java
@@ -1,13 +1,12 @@
 package org.thoughtcrime.securesms.jobs;
 
-
 import androidx.annotation.NonNull;
 
 import org.thoughtcrime.securesms.database.NoExternalStorageException;
-import org.thoughtcrime.securesms.loki.database.BackupFileRecord;
 import org.thoughtcrime.securesms.jobmanager.Data;
 import org.thoughtcrime.securesms.jobmanager.Job;
 import org.thoughtcrime.securesms.logging.Log;
+import org.thoughtcrime.securesms.loki.database.BackupFileRecord;
 import org.thoughtcrime.securesms.notifications.NotificationChannels;
 import org.thoughtcrime.securesms.service.GenericForegroundService;
 import org.thoughtcrime.securesms.util.BackupUtil;
diff --git a/src/org/thoughtcrime/securesms/loki/activities/BackupRestoreActivity.kt b/src/org/thoughtcrime/securesms/loki/activities/BackupRestoreActivity.kt
new file mode 100644
index 0000000000..5544941436
--- /dev/null
+++ b/src/org/thoughtcrime/securesms/loki/activities/BackupRestoreActivity.kt
@@ -0,0 +1,219 @@
+package org.thoughtcrime.securesms.loki.activities
+
+import android.app.Activity
+import android.app.Application
+import android.content.Intent
+import android.graphics.Typeface
+import android.net.Uri
+import android.os.Bundle
+import android.provider.OpenableColumns
+import android.text.Spannable
+import android.text.SpannableStringBuilder
+import android.text.method.LinkMovementMethod
+import android.text.style.ClickableSpan
+import android.text.style.StyleSpan
+import android.view.View
+import android.view.inputmethod.InputMethodManager
+import android.widget.Toast
+import androidx.activity.result.ActivityResult
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.activity.viewModels
+import androidx.core.widget.addTextChangedListener
+import androidx.databinding.DataBindingUtil
+import androidx.lifecycle.AndroidViewModel
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.viewModelScope
+import com.google.android.gms.common.util.Strings
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import network.loki.messenger.R
+import network.loki.messenger.databinding.ActivityBackupRestoreBinding
+import org.thoughtcrime.securesms.ApplicationContext
+import org.thoughtcrime.securesms.BaseActionBarActivity
+import org.thoughtcrime.securesms.backup.FullBackupImporter
+import org.thoughtcrime.securesms.backup.FullBackupImporter.DatabaseDowngradeException
+import org.thoughtcrime.securesms.crypto.AttachmentSecretProvider
+import org.thoughtcrime.securesms.database.DatabaseFactory
+import org.thoughtcrime.securesms.logging.Log
+import org.thoughtcrime.securesms.loki.utilities.setUpActionBarSessionLogo
+import org.thoughtcrime.securesms.loki.utilities.show
+import org.thoughtcrime.securesms.notifications.NotificationChannels
+import org.thoughtcrime.securesms.util.BackupUtil
+import org.thoughtcrime.securesms.util.TextSecurePreferences
+
+class BackupRestoreActivity : BaseActionBarActivity() {
+
+    companion object {
+        private const val TAG = "BackupRestoreActivity"
+    }
+
+    private val viewModel by viewModels<BackupRestoreViewModel>()
+
+    private val fileSelectionResultLauncher = registerForActivityResult(ActivityResultContracts.StartActivityForResult()
+    ) { result: ActivityResult ->
+        if (result.resultCode == Activity.RESULT_OK && result.data != null && result.data!!.data != null) {
+            viewModel.backupFile.value = result.data!!.data!!
+        }
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setUpActionBarSessionLogo()
+
+        val viewBinding = DataBindingUtil.setContentView<ActivityBackupRestoreBinding>(this, R.layout.activity_backup_restore)
+        viewBinding.lifecycleOwner = this
+        viewBinding.viewModel = viewModel
+
+        viewBinding.restoreButton.setOnClickListener { viewModel.tryRestoreBackup() }
+
+        viewBinding.buttonSelectFile.setOnClickListener {
+            fileSelectionResultLauncher.launch(Intent(Intent.ACTION_OPEN_DOCUMENT).apply {
+                //FIXME On some old APIs (tested on 21 & 23) the mime type doesn't filter properly
+                // and the backup files are unavailable for selection.
+//                type = BackupUtil.BACKUP_FILE_MIME_TYPE
+                type = "*/*"
+            })
+        }
+
+        viewBinding.backupCode.addTextChangedListener { text -> viewModel.backupPassphrase.value = text.toString() }
+
+        // Focus passphrase text edit when backup file is selected.
+        viewModel.backupFile.observe(this, { backupFile ->
+            if (backupFile != null) viewBinding.backupCode.post {
+                viewBinding.backupCode.requestFocus()
+                (getSystemService(INPUT_METHOD_SERVICE) as InputMethodManager)
+                        .showSoftInput(viewBinding.backupCode, InputMethodManager.SHOW_IMPLICIT)
+            }
+        })
+
+        // React to backup import result.
+        viewModel.backupImportResult.observe(this) { result ->
+            if (result != null) when (result) {
+                BackupRestoreViewModel.BackupRestoreResult.SUCCESS -> {
+                    val intent = Intent(this, HomeActivity::class.java)
+                    intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
+                    this.show(intent)
+                }
+                BackupRestoreViewModel.BackupRestoreResult.FAILURE_VERSION_DOWNGRADE ->
+                    Toast.makeText(this, R.string.RegistrationActivity_backup_failure_downgrade, Toast.LENGTH_LONG).show()
+                BackupRestoreViewModel.BackupRestoreResult.FAILURE_UNKNOWN ->
+                    Toast.makeText(this, R.string.RegistrationActivity_incorrect_backup_passphrase, Toast.LENGTH_LONG).show()
+            }
+        }
+
+        //region Legal info views
+        val termsExplanation = SpannableStringBuilder("By using this service, you agree to our Terms of Service and Privacy Policy")
+        termsExplanation.setSpan(StyleSpan(Typeface.BOLD), 40, 56, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
+        termsExplanation.setSpan(object : ClickableSpan() {
+            override fun onClick(widget: View) {
+                openURL("https://getsession.org/terms-of-service/")
+            }
+        }, 40, 56, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
+        termsExplanation.setSpan(StyleSpan(Typeface.BOLD), 61, 75, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
+        termsExplanation.setSpan(object : ClickableSpan() {
+            override fun onClick(widget: View) {
+                openURL("https://getsession.org/privacy-policy/")
+            }
+        }, 61, 75, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
+        viewBinding.termsTextView.movementMethod = LinkMovementMethod.getInstance()
+        viewBinding.termsTextView.text = termsExplanation
+        //endregion
+    }
+
+    private fun openURL(url: String) {
+        try {
+            val intent = Intent(Intent.ACTION_VIEW, Uri.parse(url))
+            startActivity(intent)
+        } catch (e: Exception) {
+            Toast.makeText(this, R.string.invalid_url, Toast.LENGTH_SHORT).show()
+        }
+    }
+}
+
+class BackupRestoreViewModel(application: Application): AndroidViewModel(application) {
+
+    companion object {
+        private const val TAG = "BackupRestoreViewModel"
+
+        @JvmStatic
+        fun uriToFileName(view: View, fileUri: Uri?): String? {
+            fileUri ?: return null
+
+            view.context.contentResolver.query(fileUri, null, null, null, null).use {
+                val nameIndex = it!!.getColumnIndex(OpenableColumns.DISPLAY_NAME)
+                it.moveToFirst()
+                return it.getString(nameIndex)
+            }
+        }
+
+        @JvmStatic
+        fun validateData(fileUri: Uri?, passphrase: String?): Boolean {
+            return fileUri != null &&
+                    !Strings.isEmptyOrWhitespace(passphrase) &&
+                    passphrase!!.length == BackupUtil.BACKUP_PASSPHRASE_LENGTH
+        }
+    }
+
+    val backupFile = MutableLiveData<Uri>(null)
+    val backupPassphrase = MutableLiveData<String>(null)
+
+    val processingBackupFile = MutableLiveData<Boolean>(false)
+    val backupImportResult = MutableLiveData<BackupRestoreResult>(null)
+
+    fun tryRestoreBackup() = viewModelScope.launch {
+        if (processingBackupFile.value == true) return@launch
+        if (backupImportResult.value == BackupRestoreResult.SUCCESS) return@launch
+        if (!validateData(backupFile.value, backupPassphrase.value)) return@launch
+
+        val context = getApplication<Application>()
+        val backupFile = backupFile.value!!
+        val passphrase = backupPassphrase.value!!
+
+        val result: BackupRestoreResult
+
+        processingBackupFile.value = true
+
+        withContext(Dispatchers.IO) {
+            result = try {
+                val database = DatabaseFactory.getBackupDatabase(context)
+                FullBackupImporter.importFromUri(
+                        context,
+                        AttachmentSecretProvider.getInstance(context).getOrCreateAttachmentSecret(),
+                        DatabaseFactory.getBackupDatabase(context),
+                        backupFile,
+                        passphrase
+                )
+                DatabaseFactory.upgradeRestored(context, database)
+                NotificationChannels.restoreContactNotificationChannels(context)
+                TextSecurePreferences.setRestorationTime(context, System.currentTimeMillis())
+                TextSecurePreferences.setHasViewedSeed(context, true)
+                TextSecurePreferences.setHasSeenWelcomeScreen(context, true)
+                TextSecurePreferences.setPromptedPushRegistration(context, true)
+                TextSecurePreferences.setHasSeenMultiDeviceRemovalSheet(context)
+                TextSecurePreferences.setHasSeenLightThemeIntroSheet(context)
+                val application = ApplicationContext.getInstance(context)
+                application.setUpStorageAPIIfNeeded()
+                application.setUpP2PAPIIfNeeded()
+
+                HomeActivity.requestResetAllSessionsOnStartup(context)
+
+                BackupRestoreResult.SUCCESS
+            } catch (e: DatabaseDowngradeException) {
+                Log.w(TAG, "Failed due to the backup being from a newer version of Signal.", e)
+                BackupRestoreResult.FAILURE_VERSION_DOWNGRADE
+            } catch (e: Exception) {
+                Log.w(TAG, e)
+                BackupRestoreResult.FAILURE_UNKNOWN
+            }
+        }
+
+        processingBackupFile.value = false
+
+        backupImportResult.value = result
+    }
+
+    enum class BackupRestoreResult {
+        SUCCESS, FAILURE_VERSION_DOWNGRADE, FAILURE_UNKNOWN
+    }
+}
\ No newline at end of file
diff --git a/src/org/thoughtcrime/securesms/loki/activities/HomeActivity.kt b/src/org/thoughtcrime/securesms/loki/activities/HomeActivity.kt
index f6e28336b4..4ec9fe606c 100644
--- a/src/org/thoughtcrime/securesms/loki/activities/HomeActivity.kt
+++ b/src/org/thoughtcrime/securesms/loki/activities/HomeActivity.kt
@@ -30,11 +30,13 @@ import network.loki.messenger.R
 import org.thoughtcrime.securesms.ApplicationContext
 import org.thoughtcrime.securesms.PassphraseRequiredActionBarActivity
 import org.thoughtcrime.securesms.conversation.ConversationActivity
+import org.thoughtcrime.securesms.database.Address
 import org.thoughtcrime.securesms.database.DatabaseFactory
 import org.thoughtcrime.securesms.database.ThreadDatabase
 import org.thoughtcrime.securesms.database.model.ThreadRecord
 import org.thoughtcrime.securesms.groups.GroupManager
 import org.thoughtcrime.securesms.jobs.MultiDeviceBlockedUpdateJob
+import org.thoughtcrime.securesms.loki.api.ResetThreadSessionJob
 import org.thoughtcrime.securesms.loki.dialogs.ConversationOptionsBottomSheet
 import org.thoughtcrime.securesms.loki.dialogs.LightThemeFeatureIntroBottomSheet
 import org.thoughtcrime.securesms.loki.dialogs.MultiDeviceRemovalBottomSheet
@@ -48,6 +50,8 @@ import org.thoughtcrime.securesms.loki.views.SeedReminderViewDelegate
 import org.thoughtcrime.securesms.mms.GlideApp
 import org.thoughtcrime.securesms.mms.GlideRequests
 import org.thoughtcrime.securesms.util.TextSecurePreferences
+import org.thoughtcrime.securesms.util.TextSecurePreferences.getBooleanPreference
+import org.thoughtcrime.securesms.util.TextSecurePreferences.setBooleanPreference
 import org.thoughtcrime.securesms.util.Util
 import org.whispersystems.signalservice.loki.api.fileserver.FileServerAPI
 import org.whispersystems.signalservice.loki.protocol.mentions.MentionsManager
@@ -59,6 +63,32 @@ import org.whispersystems.signalservice.loki.utilities.toHexString
 import java.io.IOException
 
 class HomeActivity : PassphraseRequiredActionBarActivity, ConversationClickListener, SeedReminderViewDelegate, NewConversationButtonSetViewDelegate {
+
+    companion object {
+        private const val PREF_RESET_ALL_SESSIONS_ON_START_UP = "pref_reset_all_sessions_on_start_up"
+
+        @JvmStatic
+        fun requestResetAllSessionsOnStartup(context: Context) {
+            setBooleanPreference(context, PREF_RESET_ALL_SESSIONS_ON_START_UP, true)
+        }
+
+        @JvmStatic
+        fun scheduleResetAllSessionsIfRequested(context: Context) {
+            if (!getBooleanPreference(context, PREF_RESET_ALL_SESSIONS_ON_START_UP, false)) return
+            setBooleanPreference(context, PREF_RESET_ALL_SESSIONS_ON_START_UP, false)
+
+            val jobManager = ApplicationContext.getInstance(context).jobManager
+
+            DatabaseFactory.getThreadDatabase(context).conversationListQuick.forEach { tuple ->
+                val threadId: Long = tuple.first
+                val recipientAddress: String = tuple.second
+                jobManager.add(ResetThreadSessionJob(
+                        Address.fromSerialized(recipientAddress),
+                        threadId))
+            }
+        }
+    }
+
     private lateinit var glide: GlideRequests
     private var broadcastReceiver: BroadcastReceiver? = null
 
@@ -180,6 +210,9 @@ class HomeActivity : PassphraseRequiredActionBarActivity, ConversationClickListe
             TextSecurePreferences.setWasUnlinked(this, true)
             ApplicationContext.getInstance(this).clearData()
         }
+
+        // Perform chat sessions reset if requested (usually happens after backup restoration).
+        scheduleResetAllSessionsIfRequested(this)
     }
 
     override fun onResume() {
diff --git a/src/org/thoughtcrime/securesms/loki/activities/LandingActivity.kt b/src/org/thoughtcrime/securesms/loki/activities/LandingActivity.kt
index 43901fa7b3..bf0724e902 100644
--- a/src/org/thoughtcrime/securesms/loki/activities/LandingActivity.kt
+++ b/src/org/thoughtcrime/securesms/loki/activities/LandingActivity.kt
@@ -44,6 +44,10 @@ class LandingActivity : BaseActionBarActivity(), LinkDeviceSlaveModeDialogDelega
         fakeChatView.startAnimating()
         registerButton.setOnClickListener { register() }
         restoreButton.setOnClickListener { restore() }
+        restoreBackupButton.setOnClickListener {
+            val intent = Intent(this, BackupRestoreActivity::class.java)
+            push(intent)
+        }
 //        linkButton.setOnClickListener { linkDevice() }
         if (TextSecurePreferences.getWasUnlinked(this)) {
             Toast.makeText(this, R.string.activity_landing_device_unlinked_dialog_title, Toast.LENGTH_LONG).show()
diff --git a/src/org/thoughtcrime/securesms/loki/api/ResetThreadSessionJob.kt b/src/org/thoughtcrime/securesms/loki/api/ResetThreadSessionJob.kt
new file mode 100644
index 0000000000..f9bef9df14
--- /dev/null
+++ b/src/org/thoughtcrime/securesms/loki/api/ResetThreadSessionJob.kt
@@ -0,0 +1,71 @@
+package org.thoughtcrime.securesms.loki.api
+
+import org.thoughtcrime.securesms.database.Address
+import org.thoughtcrime.securesms.jobmanager.Data
+import org.thoughtcrime.securesms.jobmanager.Job
+import org.thoughtcrime.securesms.jobmanager.impl.NetworkConstraint
+import org.thoughtcrime.securesms.jobs.BaseJob
+import org.thoughtcrime.securesms.logging.Log
+import org.thoughtcrime.securesms.recipients.Recipient
+import org.thoughtcrime.securesms.sms.MessageSender
+import org.thoughtcrime.securesms.sms.OutgoingEndSessionMessage
+import org.thoughtcrime.securesms.sms.OutgoingTextMessage
+import java.util.concurrent.TimeUnit
+
+class ResetThreadSessionJob private constructor(
+        parameters: Parameters,
+        private val address: Address,
+        private val threadId: Long)
+    : BaseJob(parameters) {
+
+    companion object {
+        const val KEY = "ResetThreadSessionJob"
+        const val DATA_KEY_ADDRESS = "address"
+        const val DATA_KEY_THREAD_ID = "thread_id"
+    }
+
+    constructor(address: Address, threadId: Long) : this(Parameters.Builder()
+            .addConstraint(NetworkConstraint.KEY)
+            .setQueue(KEY)
+            .setLifespan(TimeUnit.DAYS.toMillis(1))
+            .setMaxAttempts(Parameters.UNLIMITED)
+            .build(),
+            address,
+            threadId)
+
+    override fun serialize(): Data {
+        return Data.Builder()
+                .putParcelable(DATA_KEY_ADDRESS, address)
+                .putLong(DATA_KEY_THREAD_ID, threadId)
+                .build()
+    }
+
+    override fun getFactoryKey(): String { return KEY }
+
+    public override fun onRun() {
+        val recipient = Recipient.from(context, address, false)
+
+        // Only reset sessions for private chats.
+        if (recipient.isGroupRecipient) return
+
+        Log.v(KEY, "Resetting session for thread: \"$threadId\", recipient: \"${address.serialize()}\"")
+
+        val message = OutgoingEndSessionMessage(OutgoingTextMessage(recipient, "TERMINATE", 0, -1))
+        MessageSender.send(context, message, threadId, false, null)
+    }
+
+    public override fun onShouldRetry(e: Exception): Boolean {
+        return false
+    }
+
+    override fun onCanceled() { }
+
+    class Factory : Job.Factory<ResetThreadSessionJob> {
+
+        override fun create(parameters: Parameters, data: Data): ResetThreadSessionJob {
+            val address = data.getParcelable(DATA_KEY_ADDRESS, Address.CREATOR)
+            val threadId = data.getLong(DATA_KEY_THREAD_ID)
+            return ResetThreadSessionJob(parameters, address, threadId)
+        }
+    }
+}
diff --git a/src/org/thoughtcrime/securesms/loki/database/LokiAPIDatabase.kt b/src/org/thoughtcrime/securesms/loki/database/LokiAPIDatabase.kt
index fc7c0b44e8..5811405636 100644
--- a/src/org/thoughtcrime/securesms/loki/database/LokiAPIDatabase.kt
+++ b/src/org/thoughtcrime/securesms/loki/database/LokiAPIDatabase.kt
@@ -71,7 +71,7 @@ class LokiAPIDatabase(context: Context, helper: SQLCipherOpenHelper) : Database(
         private val openGroupPublicKeyTable = "open_group_public_keys"
         @JvmStatic val createOpenGroupPublicKeyTableCommand = "CREATE TABLE $openGroupPublicKeyTable ($server STRING PRIMARY KEY, $publicKey INTEGER DEFAULT 0);"
         // Open group profile picture cache
-        private val openGroupProfilePictureTable = "open_group_avatar_cache"
+        public val openGroupProfilePictureTable = "open_group_avatar_cache"
         private val openGroupProfilePicture = "open_group_avatar"
         @JvmStatic val createOpenGroupProfilePictureTableCommand = "CREATE TABLE $openGroupProfilePictureTable ($publicChatID STRING PRIMARY KEY, $openGroupProfilePicture TEXT NULLABLE DEFAULT NULL);"
 
diff --git a/src/org/thoughtcrime/securesms/loki/database/LokiBackupFilesDatabase.kt b/src/org/thoughtcrime/securesms/loki/database/LokiBackupFilesDatabase.kt
index 65ed0cc8bd..fd92fe4bf1 100644
--- a/src/org/thoughtcrime/securesms/loki/database/LokiBackupFilesDatabase.kt
+++ b/src/org/thoughtcrime/securesms/loki/database/LokiBackupFilesDatabase.kt
@@ -18,7 +18,7 @@ class LokiBackupFilesDatabase(context: Context, databaseHelper: SQLCipherOpenHel
     : Database(context, databaseHelper) {
 
     companion object {
-        private const val TABLE_NAME = "backup_files"
+        public  const val TABLE_NAME = "backup_files"
         private const val COLUMN_ID = "_id"
         private const val COLUMN_URI = "uri"
         private const val COLUMN_FILE_SIZE = "file_size"
diff --git a/src/org/thoughtcrime/securesms/loki/utilities/ViewUtilities.kt b/src/org/thoughtcrime/securesms/loki/utilities/ViewUtilities.kt
index 5c329762f4..c9d135ba24 100644
--- a/src/org/thoughtcrime/securesms/loki/utilities/ViewUtilities.kt
+++ b/src/org/thoughtcrime/securesms/loki/utilities/ViewUtilities.kt
@@ -42,7 +42,6 @@ fun View.fadeIn(duration: Long = 150) {
 
 fun View.fadeOut(duration: Long = 150) {
     animate().setDuration(duration).alpha(0.0f).setListener(object : AnimatorListenerAdapter() {
-
         override fun onAnimationEnd(animation: Animator?) {
             super.onAnimationEnd(animation)
             visibility = View.GONE
diff --git a/src/org/thoughtcrime/securesms/preferences/ChatsPreferenceFragment.java b/src/org/thoughtcrime/securesms/preferences/ChatsPreferenceFragment.java
index 53e9b5078e..2af518b460 100644
--- a/src/org/thoughtcrime/securesms/preferences/ChatsPreferenceFragment.java
+++ b/src/org/thoughtcrime/securesms/preferences/ChatsPreferenceFragment.java
@@ -6,6 +6,7 @@ import android.content.DialogInterface;
 import android.content.Intent;
 import android.os.Bundle;
 import android.text.TextUtils;
+import android.widget.Toast;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -18,7 +19,7 @@ import org.greenrobot.eventbus.Subscribe;
 import org.greenrobot.eventbus.ThreadMode;
 import org.thoughtcrime.securesms.ApplicationContext;
 import org.thoughtcrime.securesms.backup.BackupDialog;
-import org.thoughtcrime.securesms.backup.FullBackupBase.BackupEvent;
+import org.thoughtcrime.securesms.backup.BackupEvent;
 import org.thoughtcrime.securesms.components.SwitchPreferenceCompat;
 import org.thoughtcrime.securesms.jobs.LocalBackupJob;
 import org.thoughtcrime.securesms.logging.Log;
@@ -104,7 +105,7 @@ public class ChatsPreferenceFragment extends ListSummaryPreferenceFragment {
 
   @Subscribe(threadMode = ThreadMode.MAIN)
   public void onEvent(BackupEvent event) {
-    ProgressPreference preference = (ProgressPreference)findPreference(TextSecurePreferences.BACKUP_NOW);
+    ProgressPreference preference = findPreference(TextSecurePreferences.BACKUP_NOW);
 
     if (event.getType() == BackupEvent.Type.PROGRESS) {
       preference.setEnabled(false);
@@ -114,12 +115,21 @@ public class ChatsPreferenceFragment extends ListSummaryPreferenceFragment {
       preference.setEnabled(true);
       preference.setProgressVisible(false);
       setBackupSummary();
+
+      if (event.getException() != null) {
+        Toast.makeText(
+                getActivity(),
+                getString(R.string.preferences_chats__backup_export_error),
+                Toast.LENGTH_LONG)
+                .show();
+      }
     }
   }
 
   private void setBackupSummary() {
     findPreference(TextSecurePreferences.BACKUP_NOW)
-            .setSummary(String.format(getString(R.string.ChatsPreferenceFragment_last_backup_s), BackupUtil.getLastBackupTimeString(getContext(), Locale.getDefault())));
+            .setSummary(String.format(getString(R.string.ChatsPreferenceFragment_last_backup_s),
+                    BackupUtil.getLastBackupTimeString(getContext(), Locale.getDefault())));
   }
 
   private void setMediaDownloadSummaries() {
diff --git a/src/org/thoughtcrime/securesms/util/BackupUtil.kt b/src/org/thoughtcrime/securesms/util/BackupUtil.kt
index 0454bab3f6..6198d1a06a 100644
--- a/src/org/thoughtcrime/securesms/util/BackupUtil.kt
+++ b/src/org/thoughtcrime/securesms/util/BackupUtil.kt
@@ -13,6 +13,8 @@ import androidx.annotation.WorkerThread
 import androidx.documentfile.provider.DocumentFile
 import androidx.fragment.app.Fragment
 import network.loki.messenger.R
+import org.greenrobot.eventbus.EventBus
+import org.thoughtcrime.securesms.backup.BackupEvent
 import org.thoughtcrime.securesms.backup.BackupPassphrase
 import org.thoughtcrime.securesms.backup.FullBackupExporter
 import org.thoughtcrime.securesms.crypto.AttachmentSecretProvider
@@ -21,6 +23,8 @@ import org.thoughtcrime.securesms.loki.database.BackupFileRecord
 import org.thoughtcrime.securesms.service.LocalBackupListener
 import org.whispersystems.libsignal.util.ByteUtil
 import java.io.IOException
+import java.security.MessageDigest
+import java.security.NoSuchAlgorithmException
 import java.security.SecureRandom
 import java.text.SimpleDateFormat
 import java.util.*
@@ -28,6 +32,8 @@ import kotlin.jvm.Throws
 
 object BackupUtil {
     private const val TAG = "BackupUtil"
+    const val BACKUP_FILE_MIME_TYPE = "application/session-backup"
+    const val BACKUP_PASSPHRASE_LENGTH = 30
 
     /**
      * Set app-wide configuration to enable the backups and schedule them.
@@ -83,7 +89,7 @@ object BackupUtil {
 
     @JvmStatic
     fun generateBackupPassphrase(): Array<String> {
-        val random = ByteArray(30).also { SecureRandom().nextBytes(it) }
+        val random = ByteArray(BACKUP_PASSPHRASE_LENGTH).also { SecureRandom().nextBytes(it) }
         return Array(6) {i ->
             String.format("%05d", ByteUtil.byteArray5ToLong(random, i * 5) % 100000)
         }
@@ -151,7 +157,7 @@ object BackupUtil {
         val fileUri = DocumentsContract.createDocument(
                 context.contentResolver,
                 DocumentFile.fromTreeUri(context, dirUri)!!.uri,
-                "application/x-binary",
+                BACKUP_FILE_MIME_TYPE,
                 fileName)
 
         if (fileUri == null) {
@@ -159,17 +165,23 @@ object BackupUtil {
             throw IOException("Cannot create writable file in the dir $dirUri")
         }
 
-        FullBackupExporter.export(context,
-                AttachmentSecretProvider.getInstance(context).orCreateAttachmentSecret,
-                DatabaseFactory.getBackupDatabase(context),
-                fileUri,
-                backupPassword)
+        try {
+            FullBackupExporter.export(context,
+                    AttachmentSecretProvider.getInstance(context).getOrCreateAttachmentSecret(),
+                    DatabaseFactory.getBackupDatabase(context),
+                    fileUri,
+                    backupPassword)
+        } catch (e: Exception) {
+            // Delete the backup file on any error.
+            DocumentsContract.deleteDocument(context.contentResolver, fileUri)
+            throw e
+        }
 
         //TODO Use real file size.
         val record = DatabaseFactory.getLokiBackupFilesDatabase(context)
                 .insertBackupFile(BackupFileRecord(fileUri, -1, date))
 
-        Log.v(TAG, "Backup file was created: $fileUri")
+        Log.v(TAG, "A backup file was created: $fileUri")
 
         return record
     }
@@ -197,6 +209,25 @@ object BackupUtil {
             Log.v(TAG, "Backup file was deleted: ${record.uri}")
         }
     }
+
+    @JvmStatic
+    fun computeBackupKey(passphrase: String, salt: ByteArray?): ByteArray {
+        return try {
+            EventBus.getDefault().post(BackupEvent.createProgress(0))
+            val digest = MessageDigest.getInstance("SHA-512")
+            val input = passphrase.replace(" ", "").toByteArray()
+            var hash: ByteArray = input
+            if (salt != null) digest.update(salt)
+            for (i in 0..249999) {
+                if (i % 1000 == 0) EventBus.getDefault().post(BackupEvent.createProgress(0))
+                digest.update(hash)
+                hash = digest.digest(input)
+            }
+            ByteUtil.trim(hash, 32)
+        } catch (e: NoSuchAlgorithmException) {
+            throw AssertionError(e)
+        }
+    }
 }
 
 /**
diff --git a/src/org/thoughtcrime/securesms/util/TextSecurePreferences.java b/src/org/thoughtcrime/securesms/util/TextSecurePreferences.java
index f6bb42247f..8a31990537 100644
--- a/src/org/thoughtcrime/securesms/util/TextSecurePreferences.java
+++ b/src/org/thoughtcrime/securesms/util/TextSecurePreferences.java
@@ -13,6 +13,7 @@ import androidx.annotation.Nullable;
 import androidx.core.app.NotificationCompat;
 
 import org.greenrobot.eventbus.EventBus;
+import org.thoughtcrime.securesms.backup.BackupProtos;
 import org.thoughtcrime.securesms.jobmanager.impl.SqlCipherMigrationConstraintObserver;
 import org.thoughtcrime.securesms.lock.RegistrationLockReminders;
 import org.thoughtcrime.securesms.logging.Log;
@@ -24,10 +25,15 @@ import java.security.SecureRandom;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
 import java.util.Set;
 
 import network.loki.messenger.R;
 
+import static org.thoughtcrime.securesms.backup.FullBackupImporter.PREF_PREFIX_TYPE_BOOLEAN;
+import static org.thoughtcrime.securesms.backup.FullBackupImporter.PREF_PREFIX_TYPE_INT;
+
 public class TextSecurePreferences {
 
   private static final String TAG = TextSecurePreferences.class.getSimpleName();
@@ -141,7 +147,7 @@ public class TextSecurePreferences {
   private static final String ACTIVE_SIGNED_PRE_KEY_ID = "pref_active_signed_pre_key_id";
   private static final String NEXT_SIGNED_PRE_KEY_ID   = "pref_next_signed_pre_key_id";
 
-  public  static final String BACKUP_ENABLED              = "pref_backup_enabled_v2";
+  public  static final String BACKUP_ENABLED              = "pref_backup_enabled_v3";
   private static final String BACKUP_PASSPHRASE           = "pref_backup_passphrase";
   private static final String ENCRYPTED_BACKUP_PASSPHRASE = "pref_encrypted_backup_passphrase";
   private static final String BACKUP_TIME                 = "pref_backup_next_time";
@@ -1334,4 +1340,92 @@ public class TextSecurePreferences {
     setBooleanPreference(context, "has_seen_light_theme_intro_sheet", true);
   }
   // endregion
+
+  // region Backup related
+  public static List<BackupProtos.SharedPreference> getBackupRecords(@NonNull Context context) {
+    final SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
+
+    final String prefsFileName;
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
+      prefsFileName = PreferenceManager.getDefaultSharedPreferencesName(context);
+    } else {
+      prefsFileName = context.getPackageName() + "_preferences";
+    }
+
+    final LinkedList<BackupProtos.SharedPreference> prefList = new LinkedList<>();
+    addBackupEntryInt    (prefList, preferences, prefsFileName, LOCAL_REGISTRATION_ID_PREF);
+    addBackupEntryString (prefList, preferences, prefsFileName, LOCAL_NUMBER_PREF);
+    addBackupEntryString (prefList, preferences, prefsFileName, PROFILE_NAME_PREF);
+    addBackupEntryString (prefList, preferences, prefsFileName, PROFILE_AVATAR_URL_PREF);
+    addBackupEntryInt    (prefList, preferences, prefsFileName, PROFILE_AVATAR_ID_PREF);
+    addBackupEntryString (prefList, preferences, prefsFileName, PROFILE_KEY_PREF);
+    addBackupEntryBoolean(prefList, preferences, prefsFileName, IS_USING_FCM);
+
+    return prefList;
+  }
+
+  private static void addBackupEntryString(
+          List<BackupProtos.SharedPreference> outPrefList,
+          SharedPreferences prefs,
+          String prefFileName,
+          String prefKey) {
+    String value = prefs.getString(prefKey, null);
+    if (value == null) {
+      logBackupEntry(prefKey, false);
+      return;
+    }
+    outPrefList.add(BackupProtos.SharedPreference.newBuilder()
+              .setFile(prefFileName)
+              .setKey(prefKey)
+              .setValue(value)
+              .build());
+    logBackupEntry(prefKey, true);
+  }
+
+  private static void addBackupEntryInt(
+          List<BackupProtos.SharedPreference> outPrefList,
+          SharedPreferences prefs,
+          String prefFileName,
+          String prefKey) {
+    int value = prefs.getInt(prefKey, -1);
+    if (value == -1) {
+      logBackupEntry(prefKey, false);
+      return;
+    }
+    outPrefList.add(BackupProtos.SharedPreference.newBuilder()
+            .setFile(prefFileName)
+            .setKey(PREF_PREFIX_TYPE_INT + prefKey) // The prefix denotes the type of the preference.
+            .setValue(String.valueOf(value))
+            .build());
+    logBackupEntry(prefKey, true);
+  }
+
+  private static void addBackupEntryBoolean(
+          List<BackupProtos.SharedPreference> outPrefList,
+          SharedPreferences prefs,
+          String prefFileName,
+          String prefKey) {
+    if (!prefs.contains(prefKey)) {
+      logBackupEntry(prefKey, false);
+      return;
+    }
+    outPrefList.add(BackupProtos.SharedPreference.newBuilder()
+            .setFile(prefFileName)
+            .setKey(PREF_PREFIX_TYPE_BOOLEAN + prefKey) // The prefix denotes the type of the preference.
+            .setValue(String.valueOf(prefs.getBoolean(prefKey, false)))
+            .build());
+    logBackupEntry(prefKey, true);
+  }
+
+  private static void logBackupEntry(String prefName, boolean wasIncluded) {
+    StringBuilder sb = new StringBuilder();
+    sb.append("Backup preference ");
+    sb.append(wasIncluded ? "+ " : "- ");
+    sb.append('\"').append(prefName).append("\" ");
+    if (!wasIncluded) {
+      sb.append("(is empty and not included)");
+    }
+    Log.d(TAG, sb.toString());
+  }
+  // endregion
 }