app/src/main/java/com/stoutner/privacybrowser/activities/ImportExportActivity.java

   1 /*
   2  * Copyright © 2018-2020 Soren Stoutner <soren@stoutner.com>.
   3  *
   4  * This file is part of Privacy Browser <https://www.stoutner.com/privacy-browser>.
   5  *
   6  * Privacy Browser is free software: you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation, either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * Privacy Browser is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with Privacy Browser.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 package com.stoutner.privacybrowser.activities;
  21
  22 import android.Manifest;
  23 import android.app.Activity;
  24 import android.content.Intent;
  25 import android.content.SharedPreferences;
  26 import android.content.pm.PackageManager;
  27 import android.media.MediaScannerConnection;
  28 import android.net.Uri;
  29 import android.os.Build;
  30 import android.os.Bundle;
  31 import android.os.Environment;
  32 import android.os.Handler;
  33 import android.preference.PreferenceManager;
  34 import android.provider.DocumentsContract;
  35 import android.text.Editable;
  36 import android.text.TextWatcher;
  37 import android.view.View;
  38 import android.view.WindowManager;
  39 import android.widget.AdapterView;
  40 import android.widget.ArrayAdapter;
  41 import android.widget.Button;
  42 import android.widget.EditText;
  43 import android.widget.LinearLayout;
  44 import android.widget.RadioButton;
  45 import android.widget.Spinner;
  46 import android.widget.TextView;
  47
  48 import androidx.annotation.NonNull;
  49 import androidx.appcompat.app.ActionBar;
  50 import androidx.appcompat.app.AppCompatActivity;
  51 import androidx.appcompat.widget.Toolbar;
  52 import androidx.cardview.widget.CardView;
  53 import androidx.core.app.ActivityCompat;
  54 import androidx.core.content.ContextCompat;
  55 import androidx.core.content.FileProvider;
  56 import androidx.fragment.app.DialogFragment;
  57
  58 import com.google.android.material.snackbar.Snackbar;
  59 import com.google.android.material.textfield.TextInputLayout;
  60
  61 import com.stoutner.privacybrowser.R;
  62 import com.stoutner.privacybrowser.dialogs.StoragePermissionDialog;
  63 import com.stoutner.privacybrowser.helpers.DownloadLocationHelper;
  64 import com.stoutner.privacybrowser.helpers.FileNameHelper;
  65 import com.stoutner.privacybrowser.helpers.ImportExportDatabaseHelper;
  66
  67 import java.io.File;
  68 import java.io.FileInputStream;
  69 import java.io.FileOutputStream;
  70 import java.nio.charset.StandardCharsets;
  71 import java.security.MessageDigest;
  72 import java.security.SecureRandom;
  73 import java.util.Arrays;
  74
  75 import javax.crypto.Cipher;
  76 import javax.crypto.CipherInputStream;
  77 import javax.crypto.CipherOutputStream;
  78 import javax.crypto.spec.GCMParameterSpec;
  79 import javax.crypto.spec.SecretKeySpec;
  80
  81 public class ImportExportActivity extends AppCompatActivity implements StoragePermissionDialog.StoragePermissionDialogListener {
  82     // Create the encryption constants.
  83     private final int NO_ENCRYPTION = 0;
  84     private final int PASSWORD_ENCRYPTION = 1;
  85     private final int OPENPGP_ENCRYPTION = 2;
  86
  87     // Create the activity result constants.
  88     private final int BROWSE_RESULT_CODE = 0;
  89     private final int OPENPGP_EXPORT_RESULT_CODE = 1;
  90
  91     // `openKeychainInstalled` is accessed from an inner class.
  92     private boolean openKeychainInstalled;
  93
  94     @Override
  95     public void onCreate(Bundle savedInstanceState) {
  96         // Get a handle for the shared preferences.
  97         SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
  98
  99         // Get the screenshot preference.
 100         boolean allowScreenshots = sharedPreferences.getBoolean("allow_screenshots", false);
 101
 102         // Disable screenshots if not allowed.
 103         if (!allowScreenshots) {
 104             getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);
 105         }
 106
 107         // Set the theme.
 108         setTheme(R.style.PrivacyBrowser);
 109
 110         // Run the default commands.
 111         super.onCreate(savedInstanceState);
 112
 113         // Set the content view.
 114         setContentView(R.layout.import_export_coordinatorlayout);
 115
 116         // Set the support action bar.
 117         Toolbar toolbar = findViewById(R.id.import_export_toolbar);
 118         setSupportActionBar(toolbar);
 119
 120         // Get a handle for the action bar.
 121         ActionBar actionBar = getSupportActionBar();
 122
 123         // Remove the incorrect lint warning that the action bar might be null.
 124         assert actionBar != null;
 125
 126         // Display the home arrow on the support action bar.
 127         actionBar.setDisplayHomeAsUpEnabled(true);
 128
 129         // Find out if the system is running KitKat
 130         boolean runningKitKat = (Build.VERSION.SDK_INT == 19);
 131
 132         // Find out if OpenKeychain is installed.
 133         try {
 134             openKeychainInstalled = !getPackageManager().getPackageInfo("org.sufficientlysecure.keychain", 0).versionName.isEmpty();
 135         } catch (PackageManager.NameNotFoundException exception) {
 136             openKeychainInstalled = false;
 137         }
 138
 139         // Get handles for the views that need to be modified.
 140         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 141         TextInputLayout passwordEncryptionTextInputLayout = findViewById(R.id.password_encryption_textinputlayout);
 142         EditText encryptionPasswordEditText = findViewById(R.id.password_encryption_edittext);
 143         TextView kitKatPasswordEncryptionTextView = findViewById(R.id.kitkat_password_encryption_textview);
 144         TextView openKeychainRequiredTextView = findViewById(R.id.openkeychain_required_textview);
 145         CardView fileLocationCardView = findViewById(R.id.file_location_cardview);
 146         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 147         RadioButton exportRadioButton = findViewById(R.id.export_radiobutton);
 148         LinearLayout fileNameLinearLayout = findViewById(R.id.file_name_linearlayout);
 149         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 150         TextView fileDoesNotExistTextView = findViewById(R.id.file_does_not_exist_textview);
 151         TextView fileExistsWarningTextView = findViewById(R.id.file_exists_warning_textview);
 152         TextView openKeychainImportInstructionsTextView = findViewById(R.id.openkeychain_import_instructions_textview);
 153         Button importExportButton = findViewById(R.id.import_export_button);
 154         TextView storagePermissionTextView = findViewById(R.id.import_export_storage_permission_textview);
 155
 156         // Create an array adapter for the spinner.
 157         ArrayAdapter<CharSequence> encryptionArrayAdapter = ArrayAdapter.createFromResource(this, R.array.encryption_type, R.layout.spinner_item);
 158
 159         // Set the drop down view resource on the spinner.
 160         encryptionArrayAdapter.setDropDownViewResource(R.layout.spinner_dropdown_items);
 161
 162         // Set the array adapter for the spinner.
 163         encryptionSpinner.setAdapter(encryptionArrayAdapter);
 164
 165         // Initially hide the unneeded views.
 166         passwordEncryptionTextInputLayout.setVisibility(View.GONE);
 167         kitKatPasswordEncryptionTextView.setVisibility(View.GONE);
 168         openKeychainRequiredTextView.setVisibility(View.GONE);
 169         fileNameLinearLayout.setVisibility(View.GONE);
 170         fileDoesNotExistTextView.setVisibility(View.GONE);
 171         fileExistsWarningTextView.setVisibility(View.GONE);
 172         openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 173         importExportButton.setVisibility(View.GONE);
 174
 175         // Instantiate the download location helper.
 176         DownloadLocationHelper downloadLocationHelper = new DownloadLocationHelper();
 177
 178         // Get the default file path.
 179         String defaultFilePath = downloadLocationHelper.getDownloadLocation(this) + "/" + getString(R.string.settings_pbs);
 180
 181         // Set the other default file paths.
 182         String defaultPasswordEncryptionFilePath = defaultFilePath + ".aes";
 183         String defaultPgpFilePath = defaultFilePath + ".pgp";
 184
 185         // Set the default file path.
 186         fileNameEditText.setText(defaultFilePath);
 187
 188         // Hide the storage permission text view if the permission has already been granted.
 189         if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
 190             storagePermissionTextView.setVisibility(View.GONE);
 191         }
 192
 193         // Update the UI when the spinner changes.
 194         encryptionSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
 195             @Override
 196             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
 197                 switch (position) {
 198                     case NO_ENCRYPTION:
 199                         // Hide the unneeded layout items.
 200                         passwordEncryptionTextInputLayout.setVisibility(View.GONE);
 201                         kitKatPasswordEncryptionTextView.setVisibility(View.GONE);
 202                         openKeychainRequiredTextView.setVisibility(View.GONE);
 203                         openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 204
 205                         // Show the file location card.
 206                         fileLocationCardView.setVisibility(View.VISIBLE);
 207
 208                         // Show the file name linear layout if either import or export is checked.
 209                         if (importRadioButton.isChecked() || exportRadioButton.isChecked()) {
 210                             fileNameLinearLayout.setVisibility(View.VISIBLE);
 211                         }
 212
 213                         // Reset the text of the import button, which may have been changed to `Decrypt`.
 214                         if (importRadioButton.isChecked()) {
 215                             importExportButton.setText(R.string.import_button);
 216                         }
 217
 218                         // Reset the default file path.
 219                         fileNameEditText.setText(defaultFilePath);
 220                         break;
 221
 222                     case PASSWORD_ENCRYPTION:
 223                         if (runningKitKat) {
 224                             // Show the KitKat password encryption message.
 225                             kitKatPasswordEncryptionTextView.setVisibility(View.VISIBLE);
 226
 227                             // Hide the OpenPGP required text view and the file location card.
 228                             openKeychainRequiredTextView.setVisibility(View.GONE);
 229                             fileLocationCardView.setVisibility(View.GONE);
 230                         } else {
 231                             // Hide the OpenPGP layout items.
 232                             openKeychainRequiredTextView.setVisibility(View.GONE);
 233                             openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 234
 235                             // Show the password encryption layout items.
 236                             passwordEncryptionTextInputLayout.setVisibility(View.VISIBLE);
 237
 238                             // Show the file location card.
 239                             fileLocationCardView.setVisibility(View.VISIBLE);
 240
 241                             // Show the file name linear layout if either import or export is checked.
 242                             if (importRadioButton.isChecked() || exportRadioButton.isChecked()) {
 243                                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 244                             }
 245
 246                             // Reset the text of the import button, which may have been changed to `Decrypt`.
 247                             if (importRadioButton.isChecked()) {
 248                                 importExportButton.setText(R.string.import_button);
 249                             }
 250
 251                             // Update the default file path.
 252                             fileNameEditText.setText(defaultPasswordEncryptionFilePath);
 253                         }
 254                         break;
 255
 256                     case OPENPGP_ENCRYPTION:
 257                         // Hide the password encryption layout items.
 258                         passwordEncryptionTextInputLayout.setVisibility(View.GONE);
 259                         kitKatPasswordEncryptionTextView.setVisibility(View.GONE);
 260
 261                         // Updated items based on the installation status of OpenKeychain.
 262                         if (openKeychainInstalled) {  // OpenKeychain is installed.
 263                             // Update the default file path.
 264                             fileNameEditText.setText(defaultPgpFilePath);
 265
 266                             // Show the file location card.
 267                             fileLocationCardView.setVisibility(View.VISIBLE);
 268
 269                             if (importRadioButton.isChecked()) {
 270                                 // Show the file name linear layout and the OpenKeychain import instructions.
 271                                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 272                                 openKeychainImportInstructionsTextView.setVisibility(View.VISIBLE);
 273
 274                                 // Set the text of the import button to be `Decrypt`.
 275                                 importExportButton.setText(R.string.decrypt);
 276                             } else if (exportRadioButton.isChecked()) {
 277                                 // Hide the file name linear layout and the OpenKeychain import instructions.
 278                                 fileNameLinearLayout.setVisibility(View.GONE);
 279                                 openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 280                             }
 281                         } else {  // OpenKeychain is not installed.
 282                             // Show the OpenPGP required layout item.
 283                             openKeychainRequiredTextView.setVisibility(View.VISIBLE);
 284
 285                             // Hide the file location card.
 286                             fileLocationCardView.setVisibility(View.GONE);
 287                         }
 288                         break;
 289                 }
 290             }
 291
 292             @Override
 293             public void onNothingSelected(AdapterView<?> parent) {
 294
 295             }
 296         });
 297
 298         // Update the status of the import/export button when the password changes.
 299         encryptionPasswordEditText.addTextChangedListener(new TextWatcher() {
 300             @Override
 301             public void beforeTextChanged(CharSequence s, int start, int count, int after) {
 302                 // Do nothing.
 303             }
 304
 305             @Override
 306             public void onTextChanged(CharSequence s, int start, int before, int count) {
 307                 // Do nothing.
 308             }
 309
 310             @Override
 311             public void afterTextChanged(Editable s) {
 312                 // Get the current file name.
 313                 String fileNameString = fileNameEditText.getText().toString();
 314
 315                 // Convert the file name string to a file.
 316                 File file = new File(fileNameString);
 317
 318                 // Update the import/export button.
 319                 if (importRadioButton.isChecked()) {  // The import radio button is checked.
 320                     // Enable the import button if the file and the password exists.
 321                     importExportButton.setEnabled(file.exists() && !encryptionPasswordEditText.getText().toString().isEmpty());
 322                 } else if (exportRadioButton.isChecked()) {  // The export radio button is checked.
 323                     // Enable the export button if the file string and the password exists.
 324                     importExportButton.setEnabled(!fileNameString.isEmpty() && !encryptionPasswordEditText.getText().toString().isEmpty());
 325                 }
 326             }
 327         });
 328
 329         // Update the UI when the file name EditText changes.
 330         fileNameEditText.addTextChangedListener(new TextWatcher() {
 331             @Override
 332             public void beforeTextChanged(CharSequence s, int start, int count, int after) {
 333                 // Do nothing.
 334             }
 335
 336             @Override
 337             public void onTextChanged(CharSequence s, int start, int before, int count) {
 338                 // Do nothing.
 339             }
 340
 341             @Override
 342             public void afterTextChanged(Editable s) {
 343                 // Get the current file name.
 344                 String fileNameString = fileNameEditText.getText().toString();
 345
 346                 // Convert the file name string to a file.
 347                 File file = new File(fileNameString);
 348
 349                 // Adjust the UI according to the encryption spinner position.
 350                 switch (encryptionSpinner.getSelectedItemPosition()) {
 351                     case NO_ENCRYPTION:
 352                         // Determine if import or export is checked.
 353                         if (exportRadioButton.isChecked()) {  // The export radio button is checked.
 354                             // Hide the file does not exist text view.
 355                             fileDoesNotExistTextView.setVisibility(View.GONE);
 356
 357                             // Display a warning if the file already exists.
 358                             if (file.exists()) {
 359                                 fileExistsWarningTextView.setVisibility(View.VISIBLE);
 360                             } else {
 361                                 fileExistsWarningTextView.setVisibility(View.GONE);
 362                             }
 363
 364                             // Enable the export button if the file name is populated.
 365                             importExportButton.setEnabled(!fileNameString.isEmpty());
 366                         } else if (importRadioButton.isChecked()) {  // The import radio button is checked.
 367                             // Hide the file exists warning text view.
 368                             fileExistsWarningTextView.setVisibility(View.GONE);
 369
 370                             // Check if the file exists.
 371                             if (file.exists()) {  // The file exists.
 372                                 // Hide the notification that the file does not exist.
 373                                 fileDoesNotExistTextView.setVisibility(View.GONE);
 374
 375                                 // Enable the import button.
 376                                 importExportButton.setEnabled(true);
 377                             } else {  // The file does not exist.
 378                                 // Show a notification that the file does not exist.
 379                                 fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 380
 381                                 // Disable the import button.
 382                                 importExportButton.setEnabled(false);
 383                             }
 384                         } else {  // Neither radio button is checked.
 385                             // Hide the file notification text views.
 386                             fileExistsWarningTextView.setVisibility(View.GONE);
 387                             fileDoesNotExistTextView.setVisibility(View.GONE);
 388                         }
 389                         break;
 390
 391                     case PASSWORD_ENCRYPTION:
 392                         // Determine if import or export is checked.
 393                         if (exportRadioButton.isChecked()) {  // The export radio button is checked.
 394                             // Hide the notification that the file does not exist.
 395                             fileDoesNotExistTextView.setVisibility(View.GONE);
 396
 397                             // Display a warning if the file already exists.
 398                             if (file.exists()) {
 399                                 fileExistsWarningTextView.setVisibility(View.VISIBLE);
 400                             } else {
 401                                 fileExistsWarningTextView.setVisibility(View.GONE);
 402                             }
 403
 404                             // Enable the export button if the file name and the password are populated.
 405                             importExportButton.setEnabled(!fileNameString.isEmpty() && !encryptionPasswordEditText.getText().toString().isEmpty());
 406                         } else if (importRadioButton.isChecked()) {  // The import radio button is checked.
 407                             // Hide the file exists warning text view.
 408                             fileExistsWarningTextView.setVisibility(View.GONE);
 409
 410                             // Check if the file exists.
 411                             if (file.exists()) {  // The file exists.
 412                                 // Hide the notification that the file does not exist.
 413                                 fileDoesNotExistTextView.setVisibility(View.GONE);
 414
 415                                 // Enable the import button if the password is populated.
 416                                 importExportButton.setEnabled(!encryptionPasswordEditText.getText().toString().isEmpty());
 417                             } else {  // The file does not exist.
 418                                 // Show a notification that the file does not exist.
 419                                 fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 420
 421                                 // Disable the import button.
 422                                 importExportButton.setEnabled(false);
 423                             }
 424                         } else {  // Neither radio button is checked.
 425                             // Hide the file notification text views.
 426                             fileExistsWarningTextView.setVisibility(View.GONE);
 427                             fileDoesNotExistTextView.setVisibility(View.GONE);
 428                         }
 429                         break;
 430
 431                     case OPENPGP_ENCRYPTION:
 432                         // Hide the file exists warning text view.
 433                         fileExistsWarningTextView.setVisibility(View.GONE);
 434
 435                         if (importRadioButton.isChecked()) {  // The import radio button is checked.
 436                             if (file.exists()) {  // The file exists.
 437                                 // Hide the notification that the file does not exist.
 438                                 fileDoesNotExistTextView.setVisibility(View.GONE);
 439
 440                                 // Enable the import button if OpenKeychain is installed.
 441                                 importExportButton.setEnabled(openKeychainInstalled);
 442                             } else {  // The file does not exist.
 443                                 // Show the notification that the file does not exist.
 444                                 fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 445
 446                                 // Disable the import button.
 447                                 importExportButton.setEnabled(false);
 448                             }
 449                         } else if (exportRadioButton.isChecked()){  // The export radio button is checked.
 450                             // Hide the notification that the file does not exist.
 451                             fileDoesNotExistTextView.setVisibility(View.GONE);
 452
 453                             // Enable the export button.
 454                             importExportButton.setEnabled(true);
 455                         } else {  // Neither radio button is checked.
 456                             // Hide the notification that the file does not exist.
 457                             fileDoesNotExistTextView.setVisibility(View.GONE);
 458                         }
 459                         break;
 460                 }
 461             }
 462         });
 463     }
 464
 465     public void onClickRadioButton(View view) {
 466         // Get handles for the views.
 467         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 468         LinearLayout fileNameLinearLayout = findViewById(R.id.file_name_linearlayout);
 469         EditText passwordEncryptionEditText = findViewById(R.id.password_encryption_edittext);
 470         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 471         TextView fileDoesNotExistTextView = findViewById(R.id.file_does_not_exist_textview);
 472         TextView fileExistsWarningTextView = findViewById(R.id.file_exists_warning_textview);
 473         TextView openKeychainImportInstructionTextView = findViewById(R.id.openkeychain_import_instructions_textview);
 474         Button importExportButton = findViewById(R.id.import_export_button);
 475
 476         // Get the current file name.
 477         String fileNameString = fileNameEditText.getText().toString();
 478
 479         // Convert the file name string to a file.
 480         File file = new File(fileNameString);
 481
 482         // Check to see if import or export was selected.
 483         switch (view.getId()) {
 484             case R.id.import_radiobutton:
 485                 // Check to see if OpenPGP encryption is selected.
 486                 if (encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) {  // OpenPGP encryption selected.
 487                     // Show the OpenKeychain import instructions.
 488                     openKeychainImportInstructionTextView.setVisibility(View.VISIBLE);
 489
 490                     // Set the text on the import/export button to be `Decrypt`.
 491                     importExportButton.setText(R.string.decrypt);
 492                 } else {  // OpenPGP encryption not selected.
 493                     // Hide the OpenKeychain import instructions.
 494                     openKeychainImportInstructionTextView.setVisibility(View.GONE);
 495
 496                     // Set the text on the import/export button to be `Import`.
 497                     importExportButton.setText(R.string.import_button);
 498                 }
 499
 500                 // Hide the file exists warning text view.
 501                 fileExistsWarningTextView.setVisibility(View.GONE);
 502
 503                 // Display the file name views.
 504                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 505                 importExportButton.setVisibility(View.VISIBLE);
 506
 507                 // Check to see if the file exists.
 508                 if (file.exists()) {  // The file exists.
 509                     // Hide the notification that the file does not exist.
 510                     fileDoesNotExistTextView.setVisibility(View.GONE);
 511
 512                     // Check to see if password encryption is selected.
 513                     if (encryptionSpinner.getSelectedItemPosition() == PASSWORD_ENCRYPTION) {  // Password encryption is selected.
 514                         // Enable the import button if the encryption password is populated.
 515                         importExportButton.setEnabled(!passwordEncryptionEditText.getText().toString().isEmpty());
 516                     } else {  // Password encryption is not selected.
 517                         // Enable the import/decrypt button.
 518                         importExportButton.setEnabled(true);
 519                     }
 520                 } else {  // The file does not exist.
 521                     // Show the notification that the file does not exist.
 522                     fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 523
 524                     // Disable the import/decrypt button.
 525                     importExportButton.setEnabled(false);
 526                 }
 527                 break;
 528
 529             case R.id.export_radiobutton:
 530                 // Hide the OpenKeychain import instructions.
 531                 openKeychainImportInstructionTextView.setVisibility(View.GONE);
 532
 533                 // Set the text on the import/export button to be `Export`.
 534                 importExportButton.setText(R.string.export);
 535
 536                 // Show the import/export button.
 537                 importExportButton.setVisibility(View.VISIBLE);
 538
 539                 // Check to see if OpenPGP encryption is selected.
 540                 if (encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) {  // OpenPGP encryption is selected.
 541                     // Hide the file name views.
 542                     fileNameLinearLayout.setVisibility(View.GONE);
 543                     fileDoesNotExistTextView.setVisibility(View.GONE);
 544                     fileExistsWarningTextView.setVisibility(View.GONE);
 545
 546                     // Enable the export button.
 547                     importExportButton.setEnabled(true);
 548                 } else {  // OpenPGP encryption is not selected.
 549                     // Show the file name view.
 550                     fileNameLinearLayout.setVisibility(View.VISIBLE);
 551
 552                     // Hide the notification that the file name does not exist.
 553                     fileDoesNotExistTextView.setVisibility(View.GONE);
 554
 555                     // Display a warning if the file already exists.
 556                     if (file.exists()) {
 557                         fileExistsWarningTextView.setVisibility(View.VISIBLE);
 558                     } else {
 559                         fileExistsWarningTextView.setVisibility(View.GONE);
 560                     }
 561
 562                     // Check the encryption type.
 563                     if (encryptionSpinner.getSelectedItemPosition() == NO_ENCRYPTION) {  // No encryption is selected.
 564                         // Enable the export button if the file name is populated.
 565                         importExportButton.setEnabled(!fileNameString.isEmpty());
 566                     } else {  // Password encryption is selected.
 567                         // Enable the export button if the file name and the password are populated.
 568                         importExportButton.setEnabled(!fileNameString.isEmpty() && !passwordEncryptionEditText.getText().toString().isEmpty());
 569                     }
 570                 }
 571                 break;
 572         }
 573     }
 574
 575     public void browse(View view) {
 576         // Get a handle for the views.
 577         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 578         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 579
 580         // Check to see if import or export is selected.
 581         if (importRadioButton.isChecked()) {  // Import is selected.
 582             // Create the file picker intent.
 583             Intent importBrowseIntent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
 584
 585             // Set the intent MIME type to include all files so that everything is visible.
 586             importBrowseIntent.setType("*/*");
 587
 588             // Set the initial directory if the minimum API >= 26.
 589             if (Build.VERSION.SDK_INT >= 26) {
 590                 importBrowseIntent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, Environment.getExternalStorageDirectory());
 591             }
 592
 593             // Request a file that can be opened.
 594             importBrowseIntent.addCategory(Intent.CATEGORY_OPENABLE);
 595
 596             // Launch the file picker.
 597             startActivityForResult(importBrowseIntent, BROWSE_RESULT_CODE);
 598         } else {  // Export is selected
 599             // Create the file picker intent.
 600             Intent exportBrowseIntent = new Intent(Intent.ACTION_CREATE_DOCUMENT);
 601
 602             // Set the intent MIME type to include all files so that everything is visible.
 603             exportBrowseIntent.setType("*/*");
 604
 605             // Set the initial export file name according to the encryption type.
 606             if (encryptionSpinner.getSelectedItemPosition() == NO_ENCRYPTION) {  // No encryption is selected.
 607                 exportBrowseIntent.putExtra(Intent.EXTRA_TITLE, getString(R.string.settings_pbs));
 608             } else {  // Password encryption is selected.
 609                 exportBrowseIntent.putExtra(Intent.EXTRA_TITLE, getString(R.string.settings_pbs) + ".aes");
 610             }
 611
 612             // Set the initial directory if the minimum API >= 26.
 613             if (Build.VERSION.SDK_INT >= 26) {
 614                 exportBrowseIntent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, Environment.getExternalStorageDirectory());
 615             }
 616
 617             // Request a file that can be opened.
 618             exportBrowseIntent.addCategory(Intent.CATEGORY_OPENABLE);
 619
 620             // Launch the file picker.
 621             startActivityForResult(exportBrowseIntent, BROWSE_RESULT_CODE);
 622         }
 623     }
 624
 625     public void importExport(View view) {
 626         // Get a handle for the views.
 627         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 628         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 629         RadioButton exportRadioButton = findViewById(R.id.export_radiobutton);
 630
 631         // Check to see if the storage permission is needed.
 632         if ((encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) && exportRadioButton.isChecked()) {  // Permission not needed to export via OpenKeychain.
 633             // Export the settings.
 634             exportSettings();
 635         } else if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {  // The storage permission has been granted.
 636             // Check to see if import or export is selected.
 637             if (importRadioButton.isChecked()) {  // Import is selected.
 638                 // Import the settings.
 639                 importSettings();
 640             } else {  // Export is selected.
 641                 // Export the settings.
 642                 exportSettings();
 643             }
 644         } else {  // The storage permission has not been granted.
 645             // Get a handle for the file name EditText.
 646             EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 647
 648             // Get the file name string.
 649             String fileNameString = fileNameEditText.getText().toString();
 650
 651             // Get the external private directory `File`.
 652             File externalPrivateDirectoryFile = getExternalFilesDir(null);
 653
 654             // Remove the incorrect lint error below that the file might be null.
 655             assert externalPrivateDirectoryFile != null;
 656
 657             // Get the external private directory string.
 658             String externalPrivateDirectory = externalPrivateDirectoryFile.toString();
 659
 660             // Check to see if the file path is in the external private directory.
 661             if (fileNameString.startsWith(externalPrivateDirectory)) {  // The file path is in the external private directory.
 662                 // Check to see if import or export is selected.
 663                 if (importRadioButton.isChecked()) {  // Import is selected.
 664                     // Import the settings.
 665                     importSettings();
 666                 } else {  // Export is selected.
 667                     // Export the settings.
 668                     exportSettings();
 669                 }
 670             } else {  // The file path is in a public directory.
 671                 // Check if the user has previously denied the storage permission.
 672                 if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {  // Show a dialog explaining the request first.
 673                     // Instantiate the storage permission alert dialog.
 674                     DialogFragment storagePermissionDialogFragment = StoragePermissionDialog.displayDialog(0);
 675
 676                     // Show the storage permission alert dialog.  The permission will be requested when the dialog is closed.
 677                     storagePermissionDialogFragment.show(getSupportFragmentManager(), getString(R.string.storage_permission));
 678                 } else {  // Show the permission request directly.
 679                     // Request the storage permission.  The export will be run when it finishes.
 680                     ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);
 681                 }
 682             }
 683         }
 684     }
 685
 686     @Override
 687     public void onCloseStoragePermissionDialog(int type) {
 688         // Request the write external storage permission.  The import/export will be run when it finishes.
 689         ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);
 690     }
 691
 692     @Override
 693     public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
 694         // Get a handle for the import radiobutton.
 695         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 696
 697         // Check to see if the storage permission was granted.  If the dialog was canceled the grant results will be empty.
 698         if ((grantResults.length > 0) && (grantResults[0] == PackageManager.PERMISSION_GRANTED)) {  // The storage permission was granted.
 699             // Run the import or export methods according to which radio button is selected.
 700             if (importRadioButton.isChecked()) {  // Import is selected.
 701                 // Import the settings.
 702                 importSettings();
 703             } else {  // Export is selected.
 704                 // Export the settings.
 705                 exportSettings();
 706             }
 707         } else {  // The storage permission was not granted.
 708             // Display an error snackbar.
 709             Snackbar.make(importRadioButton, getString(R.string.cannot_use_location), Snackbar.LENGTH_LONG).show();
 710         }
 711     }
 712
 713     @Override
 714     public void onActivityResult(int requestCode, int resultCode, Intent intent) {
 715         // Run the default commands.
 716         super.onActivityResult(requestCode, resultCode, intent);
 717
 718         switch (requestCode) {
 719             case (BROWSE_RESULT_CODE):
 720                 // Don't do anything if the user pressed back from the file picker.
 721                 if (resultCode == Activity.RESULT_OK) {
 722                     // Get a handle for the views.
 723                     EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 724                     TextView fileExistsWarningTextView = findViewById(R.id.file_exists_warning_textview);
 725
 726                     // Instantiate the file name helper.
 727                     FileNameHelper fileNameHelper = new FileNameHelper();
 728
 729                     // Get the file path URI from the intent.
 730                     Uri filePathUri = intent.getData();
 731
 732                     // Use the file path from the intent if it exists.
 733                     if (filePathUri != null) {
 734                         // Convert the file name URI to a file name path.
 735                         String fileNamePath = fileNameHelper.convertUriToFileNamePath(filePathUri);
 736
 737                         // Set the file name path as the text of the file name edit text.
 738                         fileNameEditText.setText(fileNamePath);
 739
 740                         // Hide the file exists warning text view, because the file picker will have just created a file if export was selected.
 741                         fileExistsWarningTextView.setVisibility(View.GONE);
 742                     }
 743                 }
 744                 break;
 745
 746             case OPENPGP_EXPORT_RESULT_CODE:
 747                 // Get the temporary unencrypted export file.
 748                 File temporaryUnencryptedExportFile = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.settings_pbs));
 749
 750                 // Delete the temporary unencrypted export file if it exists.
 751                 if (temporaryUnencryptedExportFile.exists()) {
 752                     //noinspection ResultOfMethodCallIgnored
 753                     temporaryUnencryptedExportFile.delete();
 754                 }
 755                 break;
 756         }
 757     }
 758
 759     private void exportSettings() {
 760         // Get a handle for the views.
 761         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 762         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 763
 764         // Instantiate the import export database helper.
 765         ImportExportDatabaseHelper importExportDatabaseHelper = new ImportExportDatabaseHelper();
 766
 767         // Get the export file string.
 768         String exportFileString = fileNameEditText.getText().toString();
 769
 770         // Get the export and temporary unencrypted export files.
 771         File exportFile = new File(exportFileString);
 772         File temporaryUnencryptedExportFile = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.settings_pbs));
 773
 774         // Create an export status string.
 775         String exportStatus;
 776
 777         // Export according to the encryption type.
 778         switch (encryptionSpinner.getSelectedItemPosition()) {
 779             case NO_ENCRYPTION:
 780                 // Export the unencrypted file.
 781                 exportStatus = importExportDatabaseHelper.exportUnencrypted(exportFile, this);
 782
 783                 // Show a disposition snackbar.
 784                 if (exportStatus.equals(ImportExportDatabaseHelper.EXPORT_SUCCESSFUL)) {
 785                     Snackbar.make(fileNameEditText, getString(R.string.export_successful), Snackbar.LENGTH_SHORT).show();
 786                 } else {
 787                     Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + exportStatus, Snackbar.LENGTH_INDEFINITE).show();
 788                 }
 789                 break;
 790
 791             case PASSWORD_ENCRYPTION:
 792                 // Create an unencrypted export in a private directory.
 793                 exportStatus = importExportDatabaseHelper.exportUnencrypted(temporaryUnencryptedExportFile, this);
 794
 795                 try {
 796                     // Create an unencrypted export file input stream.
 797                     FileInputStream unencryptedExportFileInputStream = new FileInputStream(temporaryUnencryptedExportFile);
 798
 799                     // Delete the encrypted export file if it exists.
 800                     if (exportFile.exists()) {
 801                         //noinspection ResultOfMethodCallIgnored
 802                         exportFile.delete();
 803                     }
 804
 805                     // Create an encrypted export file output stream.
 806                     FileOutputStream encryptedExportFileOutputStream = new FileOutputStream(exportFile);
 807
 808                     // Get a handle for the encryption password EditText.
 809                     EditText encryptionPasswordEditText = findViewById(R.id.password_encryption_edittext);
 810
 811                     // Get the encryption password.
 812                     String encryptionPasswordString = encryptionPasswordEditText.getText().toString();
 813
 814                     // Initialize a secure random number generator.
 815                     SecureRandom secureRandom = new SecureRandom();
 816
 817                     // Get a 256 bit (32 byte) random salt.
 818                     byte[] saltByteArray = new byte[32];
 819                     secureRandom.nextBytes(saltByteArray);
 820
 821                     // Convert the encryption password to a byte array.
 822                     byte[] encryptionPasswordByteArray = encryptionPasswordString.getBytes(StandardCharsets.UTF_8);
 823
 824                     // Append the salt to the encryption password byte array.  This protects against rainbow table attacks.
 825                     byte[] encryptionPasswordWithSaltByteArray = new byte[encryptionPasswordByteArray.length + saltByteArray.length];
 826                     System.arraycopy(encryptionPasswordByteArray, 0, encryptionPasswordWithSaltByteArray, 0, encryptionPasswordByteArray.length);
 827                     System.arraycopy(saltByteArray, 0, encryptionPasswordWithSaltByteArray, encryptionPasswordByteArray.length, saltByteArray.length);
 828
 829                     // Get a SHA-512 message digest.
 830                     MessageDigest messageDigest = MessageDigest.getInstance("SHA-512");
 831
 832                     // Hash the salted encryption password.  Otherwise, any characters after the 32nd character in the password are ignored.
 833                     byte[] hashedEncryptionPasswordWithSaltByteArray = messageDigest.digest(encryptionPasswordWithSaltByteArray);
 834
 835                     // Truncate the encryption password byte array to 256 bits (32 bytes).
 836                     byte[] truncatedHashedEncryptionPasswordWithSaltByteArray = Arrays.copyOf(hashedEncryptionPasswordWithSaltByteArray, 32);
 837
 838                     // Create an AES secret key from the encryption password byte array.
 839                     SecretKeySpec secretKey = new SecretKeySpec(truncatedHashedEncryptionPasswordWithSaltByteArray, "AES");
 840
 841                     // Generate a random 12 byte initialization vector.  According to NIST, a 12 byte initialization vector is more secure than a 16 byte one.
 842                     byte[] initializationVector = new byte[12];
 843                     secureRandom.nextBytes(initializationVector);
 844
 845                     // Get a Advanced Encryption Standard, Galois/Counter Mode, No Padding cipher instance. Galois/Counter mode protects against modification of the ciphertext.  It doesn't use padding.
 846                     Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
 847
 848                     // Set the GCM tag length to be 128 bits (the maximum) and apply the initialization vector.
 849                     GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, initializationVector);
 850
 851                     // Initialize the cipher.
 852                     cipher.init(Cipher.ENCRYPT_MODE, secretKey, gcmParameterSpec);
 853
 854                     // Add the salt and the initialization vector to the export file.
 855                     encryptedExportFileOutputStream.write(saltByteArray);
 856                     encryptedExportFileOutputStream.write(initializationVector);
 857
 858                     // Create a cipher output stream.
 859                     CipherOutputStream cipherOutputStream = new CipherOutputStream(encryptedExportFileOutputStream, cipher);
 860
 861                     // Initialize variables to store data as it is moved from the unencrypted export file input stream to the cipher output stream.  Move 128 bits (16 bytes) at a time.
 862                     int numberOfBytesRead;
 863                     byte[] encryptedBytes = new byte[16];
 864
 865                     // Read up to 128 bits (16 bytes) of data from the unencrypted export file stream.  `-1` will be returned when the end of the file is reached.
 866                     while ((numberOfBytesRead = unencryptedExportFileInputStream.read(encryptedBytes)) != -1) {
 867                         // Write the data to the cipher output stream.
 868                         cipherOutputStream.write(encryptedBytes, 0, numberOfBytesRead);
 869                     }
 870
 871                     // Close the streams.
 872                     cipherOutputStream.flush();
 873                     cipherOutputStream.close();
 874                     encryptedExportFileOutputStream.close();
 875                     unencryptedExportFileInputStream.close();
 876
 877                     // Wipe the encryption data from memory.
 878                     //noinspection UnusedAssignment
 879                     encryptionPasswordString = "";
 880                     Arrays.fill(saltByteArray, (byte) 0);
 881                     Arrays.fill(encryptionPasswordByteArray, (byte) 0);
 882                     Arrays.fill(encryptionPasswordWithSaltByteArray, (byte) 0);
 883                     Arrays.fill(hashedEncryptionPasswordWithSaltByteArray, (byte) 0);
 884                     Arrays.fill(truncatedHashedEncryptionPasswordWithSaltByteArray, (byte) 0);
 885                     Arrays.fill(initializationVector, (byte) 0);
 886                     Arrays.fill(encryptedBytes, (byte) 0);
 887
 888                     // Delete the temporary unencrypted export file.
 889                     //noinspection ResultOfMethodCallIgnored
 890                     temporaryUnencryptedExportFile.delete();
 891                 } catch (Exception exception) {
 892                     exportStatus = exception.toString();
 893                 }
 894
 895                 // Show a disposition snackbar.
 896                 if (exportStatus.equals(ImportExportDatabaseHelper.EXPORT_SUCCESSFUL)) {
 897                     Snackbar.make(fileNameEditText, getString(R.string.export_successful), Snackbar.LENGTH_SHORT).show();
 898                 } else {
 899                     Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + exportStatus, Snackbar.LENGTH_INDEFINITE).show();
 900                 }
 901                 break;
 902
 903             case OPENPGP_ENCRYPTION:
 904                 // Create an unencrypted export in the private location.
 905                 importExportDatabaseHelper.exportUnencrypted(temporaryUnencryptedExportFile, this);
 906
 907                 // Create an encryption intent for OpenKeychain.
 908                 Intent openKeychainEncryptIntent = new Intent("org.sufficientlysecure.keychain.action.ENCRYPT_DATA");
 909
 910                 // Include the temporary unencrypted export file URI.
 911                 openKeychainEncryptIntent.setData(FileProvider.getUriForFile(this, getString(R.string.file_provider), temporaryUnencryptedExportFile));
 912
 913                 // Allow OpenKeychain to read the file URI.
 914                 openKeychainEncryptIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
 915
 916                 // Send the intent to the OpenKeychain package.
 917                 openKeychainEncryptIntent.setPackage("org.sufficientlysecure.keychain");
 918
 919                 // Make it so.
 920                 startActivityForResult(openKeychainEncryptIntent, OPENPGP_EXPORT_RESULT_CODE);
 921                 break;
 922         }
 923
 924         // Add the file to the list of recent files.  This doesn't currently work, but maybe it will someday.
 925         MediaScannerConnection.scanFile(this, new String[] {exportFileString}, new String[] {"application/x-sqlite3"}, null);
 926     }
 927
 928     private void importSettings() {
 929         // Get a handle for the views.
 930         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 931         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 932
 933         // Instantiate the import export database helper.
 934         ImportExportDatabaseHelper importExportDatabaseHelper = new ImportExportDatabaseHelper();
 935
 936         // Get the import file.
 937         File importFile = new File(fileNameEditText.getText().toString());
 938
 939         // Initialize the import status string
 940         String importStatus = "";
 941
 942         // Import according to the encryption type.
 943         switch (encryptionSpinner.getSelectedItemPosition()) {
 944             case NO_ENCRYPTION:
 945                 // Import the unencrypted file.
 946                 importStatus = importExportDatabaseHelper.importUnencrypted(importFile, this);
 947                 break;
 948
 949             case PASSWORD_ENCRYPTION:
 950                 // Use a private temporary import location.
 951                 File temporaryUnencryptedImportFile = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.settings_pbs));
 952
 953                 try {
 954                     // Create an encrypted import file input stream.
 955                     FileInputStream encryptedImportFileInputStream = new FileInputStream(importFile);
 956
 957                     // Delete the temporary import file if it exists.
 958                     if (temporaryUnencryptedImportFile.exists()) {
 959                         //noinspection ResultOfMethodCallIgnored
 960                         temporaryUnencryptedImportFile.delete();
 961                     }
 962
 963                     // Create an unencrypted import file output stream.
 964                     FileOutputStream unencryptedImportFileOutputStream = new FileOutputStream(temporaryUnencryptedImportFile);
 965
 966                     // Get a handle for the encryption password EditText.
 967                     EditText encryptionPasswordEditText = findViewById(R.id.password_encryption_edittext);
 968
 969                     // Get the encryption password.
 970                     String encryptionPasswordString = encryptionPasswordEditText.getText().toString();
 971
 972                     // Get the salt from the beginning of the import file.
 973                     byte[] saltByteArray = new byte[32];
 974                     //noinspection ResultOfMethodCallIgnored
 975                     encryptedImportFileInputStream.read(saltByteArray);
 976
 977                     // Get the initialization vector from the import file.
 978                     byte[] initializationVector = new byte[12];
 979                     //noinspection ResultOfMethodCallIgnored
 980                     encryptedImportFileInputStream.read(initializationVector);
 981
 982                     // Convert the encryption password to a byte array.
 983                     byte[] encryptionPasswordByteArray = encryptionPasswordString.getBytes(StandardCharsets.UTF_8);
 984
 985                     // Append the salt to the encryption password byte array.  This protects against rainbow table attacks.
 986                     byte[] encryptionPasswordWithSaltByteArray = new byte[encryptionPasswordByteArray.length + saltByteArray.length];
 987                     System.arraycopy(encryptionPasswordByteArray, 0, encryptionPasswordWithSaltByteArray, 0, encryptionPasswordByteArray.length);
 988                     System.arraycopy(saltByteArray, 0, encryptionPasswordWithSaltByteArray, encryptionPasswordByteArray.length, saltByteArray.length);
 989
 990                     // Get a SHA-512 message digest.
 991                     MessageDigest messageDigest = MessageDigest.getInstance("SHA-512");
 992
 993                     // Hash the salted encryption password.  Otherwise, any characters after the 32nd character in the password are ignored.
 994                     byte[] hashedEncryptionPasswordWithSaltByteArray = messageDigest.digest(encryptionPasswordWithSaltByteArray);
 995
 996                     // Truncate the encryption password byte array to 256 bits (32 bytes).
 997                     byte[] truncatedHashedEncryptionPasswordWithSaltByteArray = Arrays.copyOf(hashedEncryptionPasswordWithSaltByteArray, 32);
 998
 999                     // Create an AES secret key from the encryption password byte array.
1000                     SecretKeySpec secretKey = new SecretKeySpec(truncatedHashedEncryptionPasswordWithSaltByteArray, "AES");
1001
1002                     // Get a Advanced Encryption Standard, Galois/Counter Mode, No Padding cipher instance. Galois/Counter mode protects against modification of the ciphertext.  It doesn't use padding.
1003                     Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
1004
1005                     // Set the GCM tag length to be 128 bits (the maximum) and apply the initialization vector.
1006                     GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, initializationVector);
1007
1008                     // Initialize the cipher.
1009                     cipher.init(Cipher.DECRYPT_MODE, secretKey, gcmParameterSpec);
1010
1011                     // Create a cipher input stream.
1012                     CipherInputStream cipherInputStream = new CipherInputStream(encryptedImportFileInputStream, cipher);
1013
1014                     // Initialize variables to store data as it is moved from the cipher input stream to the unencrypted import file output stream.  Move 128 bits (16 bytes) at a time.
1015                     int numberOfBytesRead;
1016                     byte[] decryptedBytes = new byte[16];
1017
1018                     // Read up to 128 bits (16 bytes) of data from the cipher input stream.  `-1` will be returned when the end fo the file is reached.
1019                     while ((numberOfBytesRead = cipherInputStream.read(decryptedBytes)) != -1) {
1020                         // Write the data to the unencrypted import file output stream.
1021                         unencryptedImportFileOutputStream.write(decryptedBytes, 0, numberOfBytesRead);
1022                     }
1023
1024                     // Close the streams.
1025                     unencryptedImportFileOutputStream.flush();
1026                     unencryptedImportFileOutputStream.close();
1027                     cipherInputStream.close();
1028                     encryptedImportFileInputStream.close();
1029
1030                     // Wipe the encryption data from memory.
1031                     //noinspection UnusedAssignment
1032                     encryptionPasswordString = "";
1033                     Arrays.fill(saltByteArray, (byte) 0);
1034                     Arrays.fill(initializationVector, (byte) 0);
1035                     Arrays.fill(encryptionPasswordByteArray, (byte) 0);
1036                     Arrays.fill(encryptionPasswordWithSaltByteArray, (byte) 0);
1037                     Arrays.fill(hashedEncryptionPasswordWithSaltByteArray, (byte) 0);
1038                     Arrays.fill(truncatedHashedEncryptionPasswordWithSaltByteArray, (byte) 0);
1039                     Arrays.fill(decryptedBytes, (byte) 0);
1040
1041                     // Import the unencrypted database from the private location.
1042                     importStatus = importExportDatabaseHelper.importUnencrypted(temporaryUnencryptedImportFile, this);
1043
1044                     // Delete the temporary unencrypted import file.
1045                     //noinspection ResultOfMethodCallIgnored
1046                     temporaryUnencryptedImportFile.delete();
1047                 } catch (Exception exception) {
1048                     importStatus = exception.toString();
1049                 }
1050                 break;
1051
1052             case OPENPGP_ENCRYPTION:
1053                 try {
1054                     // Create an decryption intent for OpenKeychain.
1055                     Intent openKeychainDecryptIntent = new Intent("org.sufficientlysecure.keychain.action.DECRYPT_DATA");
1056
1057                     // Include the URI to be decrypted.
1058                     openKeychainDecryptIntent.setData(FileProvider.getUriForFile(this, getString(R.string.file_provider), importFile));
1059
1060                     // Allow OpenKeychain to read the file URI.
1061                     openKeychainDecryptIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
1062
1063                     // Send the intent to the OpenKeychain package.
1064                     openKeychainDecryptIntent.setPackage("org.sufficientlysecure.keychain");
1065
1066                     // Make it so.
1067                     startActivity(openKeychainDecryptIntent);
1068                 } catch (IllegalArgumentException exception) {  // The file import location is not valid.
1069                     // Display a snack bar with the import error.
1070                     Snackbar.make(fileNameEditText, getString(R.string.import_failed) + "  " + exception.toString(), Snackbar.LENGTH_INDEFINITE).show();
1071                 }
1072                 break;
1073         }
1074
1075         // Respond to the import disposition.
1076         if (importStatus.equals(ImportExportDatabaseHelper.IMPORT_SUCCESSFUL)) {  // The import was successful.
1077             // Create an intent to restart Privacy Browser.
1078             Intent restartIntent = getParentActivityIntent();
1079
1080             // Assert that the intent is not null to remove the lint error below.
1081             assert restartIntent != null;
1082
1083             // `Intent.FLAG_ACTIVITY_CLEAR_TASK` removes all activities from the stack.  It requires `Intent.FLAG_ACTIVITY_NEW_TASK`.
1084             restartIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
1085
1086             // Create a restart handler.
1087             Handler restartHandler = new Handler();
1088
1089             // Create a restart runnable.
1090             Runnable restartRunnable =  () -> {
1091                 // Restart Privacy Browser.
1092                 startActivity(restartIntent);
1093
1094                 // Kill this instance of Privacy Browser.  Otherwise, the app exhibits sporadic behavior after the restart.
1095                 System.exit(0);
1096             };
1097
1098             // Restart Privacy Browser after 150 milliseconds to allow enough time for the preferences to be saved.
1099             restartHandler.postDelayed(restartRunnable, 150);
1100
1101         } else if (!(encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION)){  // The import was not successful.
1102             // Display a snack bar with the import error.
1103             Snackbar.make(fileNameEditText, getString(R.string.import_failed) + "  " + importStatus, Snackbar.LENGTH_INDEFINITE).show();
1104         }
1105     }
1106 }