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.FileNameHelper;
  64 import com.stoutner.privacybrowser.helpers.ImportExportDatabaseHelper;
  65
  66 import java.io.File;
  67 import java.io.FileInputStream;
  68 import java.io.FileOutputStream;
  69 import java.nio.charset.StandardCharsets;
  70 import java.security.MessageDigest;
  71 import java.security.SecureRandom;
  72 import java.util.Arrays;
  73
  74 import javax.crypto.Cipher;
  75 import javax.crypto.CipherInputStream;
  76 import javax.crypto.CipherOutputStream;
  77 import javax.crypto.spec.GCMParameterSpec;
  78 import javax.crypto.spec.SecretKeySpec;
  79
  80 public class ImportExportActivity extends AppCompatActivity implements StoragePermissionDialog.StoragePermissionDialogListener {
  81     // Create the encryption constants.
  82     private final int NO_ENCRYPTION = 0;
  83     private final int PASSWORD_ENCRYPTION = 1;
  84     private final int OPENPGP_ENCRYPTION = 2;
  85
  86     // Create the activity result constants.
  87     private final int BROWSE_RESULT_CODE = 0;
  88     private final int OPENPGP_EXPORT_RESULT_CODE = 1;
  89
  90     // `openKeychainInstalled` is accessed from an inner class.
  91     private boolean openKeychainInstalled;
  92
  93     @Override
  94     public void onCreate(Bundle savedInstanceState) {
  95         // Get a handle for the shared preferences.
  96         SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
  97
  98         // Get the theme and screenshot preferences.
  99         boolean darkTheme = sharedPreferences.getBoolean("dark_theme", false);
 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 activity theme.
 108         if (darkTheme) {
 109             setTheme(R.style.PrivacyBrowserDark_SecondaryActivity);
 110         } else {
 111             setTheme(R.style.PrivacyBrowserLight_SecondaryActivity);
 112         }
 113
 114         // Run the default commands.
 115         super.onCreate(savedInstanceState);
 116
 117         // Set the content view.
 118         setContentView(R.layout.import_export_coordinatorlayout);
 119
 120         // Set the support action bar.
 121         Toolbar toolbar = findViewById(R.id.import_export_toolbar);
 122         setSupportActionBar(toolbar);
 123
 124         // Get a handle for the action bar.
 125         ActionBar actionBar = getSupportActionBar();
 126
 127         // Remove the incorrect lint warning that the action bar might be null.
 128         assert actionBar != null;
 129
 130         // Display the home arrow on the support action bar.
 131         actionBar.setDisplayHomeAsUpEnabled(true);
 132
 133         // Find out if the system is running KitKat
 134         boolean runningKitKat = (Build.VERSION.SDK_INT == 19);
 135
 136         // Find out if OpenKeychain is installed.
 137         try {
 138             openKeychainInstalled = !getPackageManager().getPackageInfo("org.sufficientlysecure.keychain", 0).versionName.isEmpty();
 139         } catch (PackageManager.NameNotFoundException exception) {
 140             openKeychainInstalled = false;
 141         }
 142
 143         // Get handles for the views that need to be modified.
 144         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 145         TextInputLayout passwordEncryptionTextInputLayout = findViewById(R.id.password_encryption_textinputlayout);
 146         EditText encryptionPasswordEditText = findViewById(R.id.password_encryption_edittext);
 147         TextView kitKatPasswordEncryptionTextView = findViewById(R.id.kitkat_password_encryption_textview);
 148         TextView openKeychainRequiredTextView = findViewById(R.id.openkeychain_required_textview);
 149         CardView fileLocationCardView = findViewById(R.id.file_location_cardview);
 150         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 151         RadioButton exportRadioButton = findViewById(R.id.export_radiobutton);
 152         LinearLayout fileNameLinearLayout = findViewById(R.id.file_name_linearlayout);
 153         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 154         TextView fileDoesNotExistTextView = findViewById(R.id.file_does_not_exist_textview);
 155         TextView fileExistsWarningTextView = findViewById(R.id.file_exists_warning_textview);
 156         TextView openKeychainImportInstructionsTextView = findViewById(R.id.openkeychain_import_instructions_textview);
 157         Button importExportButton = findViewById(R.id.import_export_button);
 158         TextView storagePermissionTextView = findViewById(R.id.import_export_storage_permission_textview);
 159
 160         // Create an array adapter for the spinner.
 161         ArrayAdapter<CharSequence> encryptionArrayAdapter = ArrayAdapter.createFromResource(this, R.array.encryption_type, R.layout.spinner_item);
 162
 163         // Set the drop down view resource on the spinner.
 164         encryptionArrayAdapter.setDropDownViewResource(R.layout.spinner_dropdown_items);
 165
 166         // Set the array adapter for the spinner.
 167         encryptionSpinner.setAdapter(encryptionArrayAdapter);
 168
 169         // Initially hide the unneeded views.
 170         passwordEncryptionTextInputLayout.setVisibility(View.GONE);
 171         kitKatPasswordEncryptionTextView.setVisibility(View.GONE);
 172         openKeychainRequiredTextView.setVisibility(View.GONE);
 173         fileNameLinearLayout.setVisibility(View.GONE);
 174         fileDoesNotExistTextView.setVisibility(View.GONE);
 175         fileExistsWarningTextView.setVisibility(View.GONE);
 176         openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 177         importExportButton.setVisibility(View.GONE);
 178
 179         // Create strings for the default file paths.
 180         String defaultFilePath;
 181         String defaultPasswordEncryptionFilePath;
 182         String defaultPgpFilePath;
 183
 184         // Set the default file paths according to the storage permission status.
 185         if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {  // The storage permission has been granted.
 186             // Set the default file paths to use the external public directory.
 187             defaultFilePath = Environment.getExternalStorageDirectory() + "/" + getString(R.string.settings_pbs);
 188             defaultPasswordEncryptionFilePath = defaultFilePath + ".aes";
 189             defaultPgpFilePath = defaultFilePath + ".pgp";
 190
 191             // Hide the storage permission text view.
 192             storagePermissionTextView.setVisibility(View.GONE);
 193         } else {  // The storage permission has not been granted.
 194             // Set the default file paths to use the external private directory.
 195             defaultFilePath = getApplicationContext().getExternalFilesDir(null) + "/" + getString(R.string.settings_pbs);
 196             defaultPasswordEncryptionFilePath = defaultFilePath + ".aes";
 197             defaultPgpFilePath = defaultFilePath + ".pgp";
 198         }
 199
 200         // Set the default file path.
 201         fileNameEditText.setText(defaultFilePath);
 202
 203         // Update the UI when the spinner changes.
 204         encryptionSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
 205             @Override
 206             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
 207                 switch (position) {
 208                     case NO_ENCRYPTION:
 209                         // Hide the unneeded layout items.
 210                         passwordEncryptionTextInputLayout.setVisibility(View.GONE);
 211                         kitKatPasswordEncryptionTextView.setVisibility(View.GONE);
 212                         openKeychainRequiredTextView.setVisibility(View.GONE);
 213                         openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 214
 215                         // Show the file location card.
 216                         fileLocationCardView.setVisibility(View.VISIBLE);
 217
 218                         // Show the file name linear layout if either import or export is checked.
 219                         if (importRadioButton.isChecked() || exportRadioButton.isChecked()) {
 220                             fileNameLinearLayout.setVisibility(View.VISIBLE);
 221                         }
 222
 223                         // Reset the text of the import button, which may have been changed to `Decrypt`.
 224                         if (importRadioButton.isChecked()) {
 225                             importExportButton.setText(R.string.import_button);
 226                         }
 227
 228                         // Reset the default file path.
 229                         fileNameEditText.setText(defaultFilePath);
 230                         break;
 231
 232                     case PASSWORD_ENCRYPTION:
 233                         if (runningKitKat) {
 234                             // Show the KitKat password encryption message.
 235                             kitKatPasswordEncryptionTextView.setVisibility(View.VISIBLE);
 236
 237                             // Hide the OpenPGP required text view and the file location card.
 238                             openKeychainRequiredTextView.setVisibility(View.GONE);
 239                             fileLocationCardView.setVisibility(View.GONE);
 240                         } else {
 241                             // Hide the OpenPGP layout items.
 242                             openKeychainRequiredTextView.setVisibility(View.GONE);
 243                             openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 244
 245                             // Show the password encryption layout items.
 246                             passwordEncryptionTextInputLayout.setVisibility(View.VISIBLE);
 247
 248                             // Show the file location card.
 249                             fileLocationCardView.setVisibility(View.VISIBLE);
 250
 251                             // Show the file name linear layout if either import or export is checked.
 252                             if (importRadioButton.isChecked() || exportRadioButton.isChecked()) {
 253                                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 254                             }
 255
 256                             // Reset the text of the import button, which may have been changed to `Decrypt`.
 257                             if (importRadioButton.isChecked()) {
 258                                 importExportButton.setText(R.string.import_button);
 259                             }
 260
 261                             // Update the default file path.
 262                             fileNameEditText.setText(defaultPasswordEncryptionFilePath);
 263                         }
 264                         break;
 265
 266                     case OPENPGP_ENCRYPTION:
 267                         // Hide the password encryption layout items.
 268                         passwordEncryptionTextInputLayout.setVisibility(View.GONE);
 269                         kitKatPasswordEncryptionTextView.setVisibility(View.GONE);
 270
 271                         // Updated items based on the installation status of OpenKeychain.
 272                         if (openKeychainInstalled) {  // OpenKeychain is installed.
 273                             // Update the default file path.
 274                             fileNameEditText.setText(defaultPgpFilePath);
 275
 276                             // Show the file location card.
 277                             fileLocationCardView.setVisibility(View.VISIBLE);
 278
 279                             if (importRadioButton.isChecked()) {
 280                                 // Show the file name linear layout and the OpenKeychain import instructions.
 281                                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 282                                 openKeychainImportInstructionsTextView.setVisibility(View.VISIBLE);
 283
 284                                 // Set the text of the import button to be `Decrypt`.
 285                                 importExportButton.setText(R.string.decrypt);
 286                             } else if (exportRadioButton.isChecked()) {
 287                                 // Hide the file name linear layout and the OpenKeychain import instructions.
 288                                 fileNameLinearLayout.setVisibility(View.GONE);
 289                                 openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 290                             }
 291                         } else {  // OpenKeychain is not installed.
 292                             // Show the OpenPGP required layout item.
 293                             openKeychainRequiredTextView.setVisibility(View.VISIBLE);
 294
 295                             // Hide the file location card.
 296                             fileLocationCardView.setVisibility(View.GONE);
 297                         }
 298                         break;
 299                 }
 300             }
 301
 302             @Override
 303             public void onNothingSelected(AdapterView<?> parent) {
 304
 305             }
 306         });
 307
 308         // Update the status of the import/export button when the password changes.
 309         encryptionPasswordEditText.addTextChangedListener(new TextWatcher() {
 310             @Override
 311             public void beforeTextChanged(CharSequence s, int start, int count, int after) {
 312                 // Do nothing.
 313             }
 314
 315             @Override
 316             public void onTextChanged(CharSequence s, int start, int before, int count) {
 317                 // Do nothing.
 318             }
 319
 320             @Override
 321             public void afterTextChanged(Editable s) {
 322                 // Get the current file name.
 323                 String fileNameString = fileNameEditText.getText().toString();
 324
 325                 // Convert the file name string to a file.
 326                 File file = new File(fileNameString);
 327
 328                 // Update the import/export button.
 329                 if (importRadioButton.isChecked()) {  // The import radio button is checked.
 330                     // Enable the import button if the file and the password exists.
 331                     importExportButton.setEnabled(file.exists() && !encryptionPasswordEditText.getText().toString().isEmpty());
 332                 } else if (exportRadioButton.isChecked()) {  // The export radio button is checked.
 333                     // Enable the export button if the file string and the password exists.
 334                     importExportButton.setEnabled(!fileNameString.isEmpty() && !encryptionPasswordEditText.getText().toString().isEmpty());
 335                 }
 336             }
 337         });
 338
 339         // Update the UI when the file name EditText changes.
 340         fileNameEditText.addTextChangedListener(new TextWatcher() {
 341             @Override
 342             public void beforeTextChanged(CharSequence s, int start, int count, int after) {
 343                 // Do nothing.
 344             }
 345
 346             @Override
 347             public void onTextChanged(CharSequence s, int start, int before, int count) {
 348                 // Do nothing.
 349             }
 350
 351             @Override
 352             public void afterTextChanged(Editable s) {
 353                 // Get the current file name.
 354                 String fileNameString = fileNameEditText.getText().toString();
 355
 356                 // Convert the file name string to a file.
 357                 File file = new File(fileNameString);
 358
 359                 // Adjust the UI according to the encryption spinner position.
 360                 switch (encryptionSpinner.getSelectedItemPosition()) {
 361                     case NO_ENCRYPTION:
 362                         // Determine if import or export is checked.
 363                         if (exportRadioButton.isChecked()) {  // The export radio button is checked.
 364                             // Hide the file does not exist text view.
 365                             fileDoesNotExistTextView.setVisibility(View.GONE);
 366
 367                             // Display a warning if the file already exists.
 368                             if (file.exists()) {
 369                                 fileExistsWarningTextView.setVisibility(View.VISIBLE);
 370                             } else {
 371                                 fileExistsWarningTextView.setVisibility(View.GONE);
 372                             }
 373
 374                             // Enable the export button if the file name is populated.
 375                             importExportButton.setEnabled(!fileNameString.isEmpty());
 376                         } else if (importRadioButton.isChecked()) {  // The import radio button is checked.
 377                             // Hide the file exists warning text view.
 378                             fileExistsWarningTextView.setVisibility(View.GONE);
 379
 380                             // Check if the file exists.
 381                             if (file.exists()) {  // The file exists.
 382                                 // Hide the notification that the file does not exist.
 383                                 fileDoesNotExistTextView.setVisibility(View.GONE);
 384
 385                                 // Enable the import button.
 386                                 importExportButton.setEnabled(true);
 387                             } else {  // The file does not exist.
 388                                 // Show a notification that the file does not exist.
 389                                 fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 390
 391                                 // Disable the import button.
 392                                 importExportButton.setEnabled(false);
 393                             }
 394                         } else {  // Neither radio button is checked.
 395                             // Hide the file notification text views.
 396                             fileExistsWarningTextView.setVisibility(View.GONE);
 397                             fileDoesNotExistTextView.setVisibility(View.GONE);
 398                         }
 399                         break;
 400
 401                     case PASSWORD_ENCRYPTION:
 402                         // Determine if import or export is checked.
 403                         if (exportRadioButton.isChecked()) {  // The export radio button is checked.
 404                             // Hide the notification that the file does not exist.
 405                             fileDoesNotExistTextView.setVisibility(View.GONE);
 406
 407                             // Display a warning if the file already exists.
 408                             if (file.exists()) {
 409                                 fileExistsWarningTextView.setVisibility(View.VISIBLE);
 410                             } else {
 411                                 fileExistsWarningTextView.setVisibility(View.GONE);
 412                             }
 413
 414                             // Enable the export button if the file name and the password are populated.
 415                             importExportButton.setEnabled(!fileNameString.isEmpty() && !encryptionPasswordEditText.getText().toString().isEmpty());
 416                         } else if (importRadioButton.isChecked()) {  // The import radio button is checked.
 417                             // Hide the file exists warning text view.
 418                             fileExistsWarningTextView.setVisibility(View.GONE);
 419
 420                             // Check if the file exists.
 421                             if (file.exists()) {  // The file exists.
 422                                 // Hide the notification that the file does not exist.
 423                                 fileDoesNotExistTextView.setVisibility(View.GONE);
 424
 425                                 // Enable the import button if the password is populated.
 426                                 importExportButton.setEnabled(!encryptionPasswordEditText.getText().toString().isEmpty());
 427                             } else {  // The file does not exist.
 428                                 // Show a notification that the file does not exist.
 429                                 fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 430
 431                                 // Disable the import button.
 432                                 importExportButton.setEnabled(false);
 433                             }
 434                         } else {  // Neither radio button is checked.
 435                             // Hide the file notification text views.
 436                             fileExistsWarningTextView.setVisibility(View.GONE);
 437                             fileDoesNotExistTextView.setVisibility(View.GONE);
 438                         }
 439                         break;
 440
 441                     case OPENPGP_ENCRYPTION:
 442                         // Hide the file exists warning text view.
 443                         fileExistsWarningTextView.setVisibility(View.GONE);
 444
 445                         if (importRadioButton.isChecked()) {  // The import radio button is checked.
 446                             if (file.exists()) {  // The file exists.
 447                                 // Hide the notification that the file does not exist.
 448                                 fileDoesNotExistTextView.setVisibility(View.GONE);
 449
 450                                 // Enable the import button if OpenKeychain is installed.
 451                                 importExportButton.setEnabled(openKeychainInstalled);
 452                             } else {  // The file does not exist.
 453                                 // Show the notification that the file does not exist.
 454                                 fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 455
 456                                 // Disable the import button.
 457                                 importExportButton.setEnabled(false);
 458                             }
 459                         } else if (exportRadioButton.isChecked()){  // The export radio button is checked.
 460                             // Hide the notification that the file does not exist.
 461                             fileDoesNotExistTextView.setVisibility(View.GONE);
 462
 463                             // Enable the export button.
 464                             importExportButton.setEnabled(true);
 465                         } else {  // Neither radio button is checked.
 466                             // Hide the notification that the file does not exist.
 467                             fileDoesNotExistTextView.setVisibility(View.GONE);
 468                         }
 469                         break;
 470                 }
 471             }
 472         });
 473     }
 474
 475     public void onClickRadioButton(View view) {
 476         // Get handles for the views.
 477         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 478         LinearLayout fileNameLinearLayout = findViewById(R.id.file_name_linearlayout);
 479         EditText passwordEncryptionEditText = findViewById(R.id.password_encryption_edittext);
 480         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 481         TextView fileDoesNotExistTextView = findViewById(R.id.file_does_not_exist_textview);
 482         TextView fileExistsWarningTextView = findViewById(R.id.file_exists_warning_textview);
 483         TextView openKeychainImportInstructionTextView = findViewById(R.id.openkeychain_import_instructions_textview);
 484         Button importExportButton = findViewById(R.id.import_export_button);
 485
 486         // Get the current file name.
 487         String fileNameString = fileNameEditText.getText().toString();
 488
 489         // Convert the file name string to a file.
 490         File file = new File(fileNameString);
 491
 492         // Check to see if import or export was selected.
 493         switch (view.getId()) {
 494             case R.id.import_radiobutton:
 495                 // Check to see if OpenPGP encryption is selected.
 496                 if (encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) {  // OpenPGP encryption selected.
 497                     // Show the OpenKeychain import instructions.
 498                     openKeychainImportInstructionTextView.setVisibility(View.VISIBLE);
 499
 500                     // Set the text on the import/export button to be `Decrypt`.
 501                     importExportButton.setText(R.string.decrypt);
 502                 } else {  // OpenPGP encryption not selected.
 503                     // Hide the OpenKeychain import instructions.
 504                     openKeychainImportInstructionTextView.setVisibility(View.GONE);
 505
 506                     // Set the text on the import/export button to be `Import`.
 507                     importExportButton.setText(R.string.import_button);
 508                 }
 509
 510                 // Hide the file exists warning text view.
 511                 fileExistsWarningTextView.setVisibility(View.GONE);
 512
 513                 // Display the file name views.
 514                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 515                 importExportButton.setVisibility(View.VISIBLE);
 516
 517                 // Check to see if the file exists.
 518                 if (file.exists()) {  // The file exists.
 519                     // Hide the notification that the file does not exist.
 520                     fileDoesNotExistTextView.setVisibility(View.GONE);
 521
 522                     // Check to see if password encryption is selected.
 523                     if (encryptionSpinner.getSelectedItemPosition() == PASSWORD_ENCRYPTION) {  // Password encryption is selected.
 524                         // Enable the import button if the encryption password is populated.
 525                         importExportButton.setEnabled(!passwordEncryptionEditText.getText().toString().isEmpty());
 526                     } else {  // Password encryption is not selected.
 527                         // Enable the import/decrypt button.
 528                         importExportButton.setEnabled(true);
 529                     }
 530                 } else {  // The file does not exist.
 531                     // Show the notification that the file does not exist.
 532                     fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 533
 534                     // Disable the import/decrypt button.
 535                     importExportButton.setEnabled(false);
 536                 }
 537                 break;
 538
 539             case R.id.export_radiobutton:
 540                 // Hide the OpenKeychain import instructions.
 541                 openKeychainImportInstructionTextView.setVisibility(View.GONE);
 542
 543                 // Set the text on the import/export button to be `Export`.
 544                 importExportButton.setText(R.string.export);
 545
 546                 // Show the import/export button.
 547                 importExportButton.setVisibility(View.VISIBLE);
 548
 549                 // Check to see if OpenPGP encryption is selected.
 550                 if (encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) {  // OpenPGP encryption is selected.
 551                     // Hide the file name views.
 552                     fileNameLinearLayout.setVisibility(View.GONE);
 553                     fileDoesNotExistTextView.setVisibility(View.GONE);
 554                     fileExistsWarningTextView.setVisibility(View.GONE);
 555
 556                     // Enable the export button.
 557                     importExportButton.setEnabled(true);
 558                 } else {  // OpenPGP encryption is not selected.
 559                     // Show the file name view.
 560                     fileNameLinearLayout.setVisibility(View.VISIBLE);
 561
 562                     // Hide the notification that the file name does not exist.
 563                     fileDoesNotExistTextView.setVisibility(View.GONE);
 564
 565                     // Display a warning if the file already exists.
 566                     if (file.exists()) {
 567                         fileExistsWarningTextView.setVisibility(View.VISIBLE);
 568                     } else {
 569                         fileExistsWarningTextView.setVisibility(View.GONE);
 570                     }
 571
 572                     // Check the encryption type.
 573                     if (encryptionSpinner.getSelectedItemPosition() == NO_ENCRYPTION) {  // No encryption is selected.
 574                         // Enable the export button if the file name is populated.
 575                         importExportButton.setEnabled(!fileNameString.isEmpty());
 576                     } else {  // Password encryption is selected.
 577                         // Enable the export button if the file name and the password are populated.
 578                         importExportButton.setEnabled(!fileNameString.isEmpty() && !passwordEncryptionEditText.getText().toString().isEmpty());
 579                     }
 580                 }
 581                 break;
 582         }
 583     }
 584
 585     public void browse(View view) {
 586         // Get a handle for the views.
 587         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 588         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 589
 590         // Check to see if import or export is selected.
 591         if (importRadioButton.isChecked()) {  // Import is selected.
 592             // Create the file picker intent.
 593             Intent importBrowseIntent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
 594
 595             // Set the intent MIME type to include all files so that everything is visible.
 596             importBrowseIntent.setType("*/*");
 597
 598             // Set the initial directory if the minimum API >= 26.
 599             if (Build.VERSION.SDK_INT >= 26) {
 600                 importBrowseIntent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, Environment.getExternalStorageDirectory());
 601             }
 602
 603             // Request a file that can be opened.
 604             importBrowseIntent.addCategory(Intent.CATEGORY_OPENABLE);
 605
 606             // Launch the file picker.
 607             startActivityForResult(importBrowseIntent, BROWSE_RESULT_CODE);
 608         } else {  // Export is selected
 609             // Create the file picker intent.
 610             Intent exportBrowseIntent = new Intent(Intent.ACTION_CREATE_DOCUMENT);
 611
 612             // Set the intent MIME type to include all files so that everything is visible.
 613             exportBrowseIntent.setType("*/*");
 614
 615             // Set the initial export file name according to the encryption type.
 616             if (encryptionSpinner.getSelectedItemPosition() == NO_ENCRYPTION) {  // No encryption is selected.
 617                 exportBrowseIntent.putExtra(Intent.EXTRA_TITLE, getString(R.string.settings_pbs));
 618             } else {  // Password encryption is selected.
 619                 exportBrowseIntent.putExtra(Intent.EXTRA_TITLE, getString(R.string.settings_pbs) + ".aes");
 620             }
 621
 622             // Set the initial directory if the minimum API >= 26.
 623             if (Build.VERSION.SDK_INT >= 26) {
 624                 exportBrowseIntent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, Environment.getExternalStorageDirectory());
 625             }
 626
 627             // Request a file that can be opened.
 628             exportBrowseIntent.addCategory(Intent.CATEGORY_OPENABLE);
 629
 630             // Launch the file picker.
 631             startActivityForResult(exportBrowseIntent, BROWSE_RESULT_CODE);
 632         }
 633     }
 634
 635     public void importExport(View view) {
 636         // Get a handle for the views.
 637         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 638         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 639         RadioButton exportRadioButton = findViewById(R.id.export_radiobutton);
 640
 641         // Check to see if the storage permission is needed.
 642         if ((encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) && exportRadioButton.isChecked()) {  // Permission not needed to export via OpenKeychain.
 643             // Export the settings.
 644             exportSettings();
 645         } else if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {  // The storage permission has been granted.
 646             // Check to see if import or export is selected.
 647             if (importRadioButton.isChecked()) {  // Import is selected.
 648                 // Import the settings.
 649                 importSettings();
 650             } else {  // Export is selected.
 651                 // Export the settings.
 652                 exportSettings();
 653             }
 654         } else {  // The storage permission has not been granted.
 655             // Get a handle for the file name EditText.
 656             EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 657
 658             // Get the file name string.
 659             String fileNameString = fileNameEditText.getText().toString();
 660
 661             // Get the external private directory `File`.
 662             File externalPrivateDirectoryFile = getExternalFilesDir(null);
 663
 664             // Remove the incorrect lint error below that the file might be null.
 665             assert externalPrivateDirectoryFile != null;
 666
 667             // Get the external private directory string.
 668             String externalPrivateDirectory = externalPrivateDirectoryFile.toString();
 669
 670             // Check to see if the file path is in the external private directory.
 671             if (fileNameString.startsWith(externalPrivateDirectory)) {  // The file path is in the external private directory.
 672                 // Check to see if import or export is selected.
 673                 if (importRadioButton.isChecked()) {  // Import is selected.
 674                     // Import the settings.
 675                     importSettings();
 676                 } else {  // Export is selected.
 677                     // Export the settings.
 678                     exportSettings();
 679                 }
 680             } else {  // The file path is in a public directory.
 681                 // Check if the user has previously denied the storage permission.
 682                 if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {  // Show a dialog explaining the request first.
 683                     // Instantiate the storage permission alert dialog.
 684                     DialogFragment storagePermissionDialogFragment = StoragePermissionDialog.displayDialog(0);
 685
 686                     // Show the storage permission alert dialog.  The permission will be requested when the dialog is closed.
 687                     storagePermissionDialogFragment.show(getSupportFragmentManager(), getString(R.string.storage_permission));
 688                 } else {  // Show the permission request directly.
 689                     // Request the storage permission.  The export will be run when it finishes.
 690                     ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);
 691                 }
 692             }
 693         }
 694     }
 695
 696     @Override
 697     public void onCloseStoragePermissionDialog(int type) {
 698         // Request the write external storage permission.  The import/export will be run when it finishes.
 699         ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);
 700     }
 701
 702     @Override
 703     public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
 704         // Get a handle for the import radiobutton.
 705         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 706
 707         // Check to see if the storage permission was granted.  If the dialog was canceled the grant results will be empty.
 708         if ((grantResults.length > 0) && (grantResults[0] == PackageManager.PERMISSION_GRANTED)) {  // The storage permission was granted.
 709             // Run the import or export methods according to which radio button is selected.
 710             if (importRadioButton.isChecked()) {  // Import is selected.
 711                 // Import the settings.
 712                 importSettings();
 713             } else {  // Export is selected.
 714                 // Export the settings.
 715                 exportSettings();
 716             }
 717         } else {  // The storage permission was not granted.
 718             // Display an error snackbar.
 719             Snackbar.make(importRadioButton, getString(R.string.cannot_use_location), Snackbar.LENGTH_LONG).show();
 720         }
 721     }
 722
 723     @Override
 724     public void onActivityResult(int requestCode, int resultCode, Intent intent) {
 725         // Run the default commands.
 726         super.onActivityResult(requestCode, resultCode, intent);
 727
 728         switch (requestCode) {
 729             case (BROWSE_RESULT_CODE):
 730                 // Don't do anything if the user pressed back from the file picker.
 731                 if (resultCode == Activity.RESULT_OK) {
 732                     // Get a handle for the views.
 733                     EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 734                     TextView fileExistsWarningTextView = findViewById(R.id.file_exists_warning_textview);
 735
 736                     // Instantiate the file name helper.
 737                     FileNameHelper fileNameHelper = new FileNameHelper();
 738
 739                     // Get the file path URI from the intent.
 740                     Uri filePathUri = intent.getData();
 741
 742                     // Use the file path from the intent if it exists.
 743                     if (filePathUri != null) {
 744                         // Convert the file name URI to a file name path.
 745                         String fileNamePath = fileNameHelper.convertUriToFileNamePath(filePathUri);
 746
 747                         // Set the file name path as the text of the file name edit text.
 748                         fileNameEditText.setText(fileNamePath);
 749
 750                         // Hide the file exists warning text view, because the file picker will have just created a file if export was selected.
 751                         fileExistsWarningTextView.setVisibility(View.GONE);
 752                     }
 753                 }
 754                 break;
 755
 756             case OPENPGP_EXPORT_RESULT_CODE:
 757                 // Get the temporary unencrypted export file.
 758                 File temporaryUnencryptedExportFile = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.settings_pbs));
 759
 760                 // Delete the temporary unencrypted export file if it exists.
 761                 if (temporaryUnencryptedExportFile.exists()) {
 762                     //noinspection ResultOfMethodCallIgnored
 763                     temporaryUnencryptedExportFile.delete();
 764                 }
 765                 break;
 766         }
 767     }
 768
 769     private void exportSettings() {
 770         // Get a handle for the views.
 771         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 772         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 773
 774         // Instantiate the import export database helper.
 775         ImportExportDatabaseHelper importExportDatabaseHelper = new ImportExportDatabaseHelper();
 776
 777         // Get the export file string.
 778         String exportFileString = fileNameEditText.getText().toString();
 779
 780         // Get the export and temporary unencrypted export files.
 781         File exportFile = new File(exportFileString);
 782         File temporaryUnencryptedExportFile = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.settings_pbs));
 783
 784         // Create an export status string.
 785         String exportStatus;
 786
 787         // Export according to the encryption type.
 788         switch (encryptionSpinner.getSelectedItemPosition()) {
 789             case NO_ENCRYPTION:
 790                 // Export the unencrypted file.
 791                 exportStatus = importExportDatabaseHelper.exportUnencrypted(exportFile, this);
 792
 793                 // Show a disposition snackbar.
 794                 if (exportStatus.equals(ImportExportDatabaseHelper.EXPORT_SUCCESSFUL)) {
 795                     Snackbar.make(fileNameEditText, getString(R.string.export_successful), Snackbar.LENGTH_SHORT).show();
 796                 } else {
 797                     Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + exportStatus, Snackbar.LENGTH_INDEFINITE).show();
 798                 }
 799                 break;
 800
 801             case PASSWORD_ENCRYPTION:
 802                 // Create an unencrypted export in a private directory.
 803                 exportStatus = importExportDatabaseHelper.exportUnencrypted(temporaryUnencryptedExportFile, this);
 804
 805                 try {
 806                     // Create an unencrypted export file input stream.
 807                     FileInputStream unencryptedExportFileInputStream = new FileInputStream(temporaryUnencryptedExportFile);
 808
 809                     // Delete the encrypted export file if it exists.
 810                     if (exportFile.exists()) {
 811                         //noinspection ResultOfMethodCallIgnored
 812                         exportFile.delete();
 813                     }
 814
 815                     // Create an encrypted export file output stream.
 816                     FileOutputStream encryptedExportFileOutputStream = new FileOutputStream(exportFile);
 817
 818                     // Get a handle for the encryption password EditText.
 819                     EditText encryptionPasswordEditText = findViewById(R.id.password_encryption_edittext);
 820
 821                     // Get the encryption password.
 822                     String encryptionPasswordString = encryptionPasswordEditText.getText().toString();
 823
 824                     // Initialize a secure random number generator.
 825                     SecureRandom secureRandom = new SecureRandom();
 826
 827                     // Get a 256 bit (32 byte) random salt.
 828                     byte[] saltByteArray = new byte[32];
 829                     secureRandom.nextBytes(saltByteArray);
 830
 831                     // Convert the encryption password to a byte array.
 832                     byte[] encryptionPasswordByteArray = encryptionPasswordString.getBytes(StandardCharsets.UTF_8);
 833
 834                     // Append the salt to the encryption password byte array.  This protects against rainbow table attacks.
 835                     byte[] encryptionPasswordWithSaltByteArray = new byte[encryptionPasswordByteArray.length + saltByteArray.length];
 836                     System.arraycopy(encryptionPasswordByteArray, 0, encryptionPasswordWithSaltByteArray, 0, encryptionPasswordByteArray.length);
 837                     System.arraycopy(saltByteArray, 0, encryptionPasswordWithSaltByteArray, encryptionPasswordByteArray.length, saltByteArray.length);
 838
 839                     // Get a SHA-512 message digest.
 840                     MessageDigest messageDigest = MessageDigest.getInstance("SHA-512");
 841
 842                     // Hash the salted encryption password.  Otherwise, any characters after the 32nd character in the password are ignored.
 843                     byte[] hashedEncryptionPasswordWithSaltByteArray = messageDigest.digest(encryptionPasswordWithSaltByteArray);
 844
 845                     // Truncate the encryption password byte array to 256 bits (32 bytes).
 846                     byte[] truncatedHashedEncryptionPasswordWithSaltByteArray = Arrays.copyOf(hashedEncryptionPasswordWithSaltByteArray, 32);
 847
 848                     // Create an AES secret key from the encryption password byte array.
 849                     SecretKeySpec secretKey = new SecretKeySpec(truncatedHashedEncryptionPasswordWithSaltByteArray, "AES");
 850
 851                     // Generate a random 12 byte initialization vector.  According to NIST, a 12 byte initialization vector is more secure than a 16 byte one.
 852                     byte[] initializationVector = new byte[12];
 853                     secureRandom.nextBytes(initializationVector);
 854
 855                     // 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.
 856                     Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
 857
 858                     // Set the GCM tag length to be 128 bits (the maximum) and apply the initialization vector.
 859                     GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, initializationVector);
 860
 861                     // Initialize the cipher.
 862                     cipher.init(Cipher.ENCRYPT_MODE, secretKey, gcmParameterSpec);
 863
 864                     // Add the salt and the initialization vector to the export file.
 865                     encryptedExportFileOutputStream.write(saltByteArray);
 866                     encryptedExportFileOutputStream.write(initializationVector);
 867
 868                     // Create a cipher output stream.
 869                     CipherOutputStream cipherOutputStream = new CipherOutputStream(encryptedExportFileOutputStream, cipher);
 870
 871                     // 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.
 872                     int numberOfBytesRead;
 873                     byte[] encryptedBytes = new byte[16];
 874
 875                     // 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.
 876                     while ((numberOfBytesRead = unencryptedExportFileInputStream.read(encryptedBytes)) != -1) {
 877                         // Write the data to the cipher output stream.
 878                         cipherOutputStream.write(encryptedBytes, 0, numberOfBytesRead);
 879                     }
 880
 881                     // Close the streams.
 882                     cipherOutputStream.flush();
 883                     cipherOutputStream.close();
 884                     encryptedExportFileOutputStream.close();
 885                     unencryptedExportFileInputStream.close();
 886
 887                     // Wipe the encryption data from memory.
 888                     //noinspection UnusedAssignment
 889                     encryptionPasswordString = "";
 890                     Arrays.fill(saltByteArray, (byte) 0);
 891                     Arrays.fill(encryptionPasswordByteArray, (byte) 0);
 892                     Arrays.fill(encryptionPasswordWithSaltByteArray, (byte) 0);
 893                     Arrays.fill(hashedEncryptionPasswordWithSaltByteArray, (byte) 0);
 894                     Arrays.fill(truncatedHashedEncryptionPasswordWithSaltByteArray, (byte) 0);
 895                     Arrays.fill(initializationVector, (byte) 0);
 896                     Arrays.fill(encryptedBytes, (byte) 0);
 897
 898                     // Delete the temporary unencrypted export file.
 899                     //noinspection ResultOfMethodCallIgnored
 900                     temporaryUnencryptedExportFile.delete();
 901                 } catch (Exception exception) {
 902                     exportStatus = exception.toString();
 903                 }
 904
 905                 // Show a disposition snackbar.
 906                 if (exportStatus.equals(ImportExportDatabaseHelper.EXPORT_SUCCESSFUL)) {
 907                     Snackbar.make(fileNameEditText, getString(R.string.export_successful), Snackbar.LENGTH_SHORT).show();
 908                 } else {
 909                     Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + exportStatus, Snackbar.LENGTH_INDEFINITE).show();
 910                 }
 911                 break;
 912
 913             case OPENPGP_ENCRYPTION:
 914                 // Create an unencrypted export in the private location.
 915                 importExportDatabaseHelper.exportUnencrypted(temporaryUnencryptedExportFile, this);
 916
 917                 // Create an encryption intent for OpenKeychain.
 918                 Intent openKeychainEncryptIntent = new Intent("org.sufficientlysecure.keychain.action.ENCRYPT_DATA");
 919
 920                 // Include the temporary unencrypted export file URI.
 921                 openKeychainEncryptIntent.setData(FileProvider.getUriForFile(this, getString(R.string.file_provider), temporaryUnencryptedExportFile));
 922
 923                 // Allow OpenKeychain to read the file URI.
 924                 openKeychainEncryptIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
 925
 926                 // Send the intent to the OpenKeychain package.
 927                 openKeychainEncryptIntent.setPackage("org.sufficientlysecure.keychain");
 928
 929                 // Make it so.
 930                 startActivityForResult(openKeychainEncryptIntent, OPENPGP_EXPORT_RESULT_CODE);
 931                 break;
 932         }
 933
 934         // Add the file to the list of recent files.  This doesn't currently work, but maybe it will someday.
 935         MediaScannerConnection.scanFile(this, new String[] {exportFileString}, new String[] {"application/x-sqlite3"}, null);
 936     }
 937
 938     private void importSettings() {
 939         // Get a handle for the views.
 940         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 941         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 942
 943         // Instantiate the import export database helper.
 944         ImportExportDatabaseHelper importExportDatabaseHelper = new ImportExportDatabaseHelper();
 945
 946         // Get the import file.
 947         File importFile = new File(fileNameEditText.getText().toString());
 948
 949         // Initialize the import status string
 950         String importStatus = "";
 951
 952         // Import according to the encryption type.
 953         switch (encryptionSpinner.getSelectedItemPosition()) {
 954             case NO_ENCRYPTION:
 955                 // Import the unencrypted file.
 956                 importStatus = importExportDatabaseHelper.importUnencrypted(importFile, this);
 957                 break;
 958
 959             case PASSWORD_ENCRYPTION:
 960                 // Use a private temporary import location.
 961                 File temporaryUnencryptedImportFile = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.settings_pbs));
 962
 963                 try {
 964                     // Create an encrypted import file input stream.
 965                     FileInputStream encryptedImportFileInputStream = new FileInputStream(importFile);
 966
 967                     // Delete the temporary import file if it exists.
 968                     if (temporaryUnencryptedImportFile.exists()) {
 969                         //noinspection ResultOfMethodCallIgnored
 970                         temporaryUnencryptedImportFile.delete();
 971                     }
 972
 973                     // Create an unencrypted import file output stream.
 974                     FileOutputStream unencryptedImportFileOutputStream = new FileOutputStream(temporaryUnencryptedImportFile);
 975
 976                     // Get a handle for the encryption password EditText.
 977                     EditText encryptionPasswordEditText = findViewById(R.id.password_encryption_edittext);
 978
 979                     // Get the encryption password.
 980                     String encryptionPasswordString = encryptionPasswordEditText.getText().toString();
 981
 982                     // Get the salt from the beginning of the import file.
 983                     byte[] saltByteArray = new byte[32];
 984                     //noinspection ResultOfMethodCallIgnored
 985                     encryptedImportFileInputStream.read(saltByteArray);
 986
 987                     // Get the initialization vector from the import file.
 988                     byte[] initializationVector = new byte[12];
 989                     //noinspection ResultOfMethodCallIgnored
 990                     encryptedImportFileInputStream.read(initializationVector);
 991
 992                     // Convert the encryption password to a byte array.
 993                     byte[] encryptionPasswordByteArray = encryptionPasswordString.getBytes(StandardCharsets.UTF_8);
 994
 995                     // Append the salt to the encryption password byte array.  This protects against rainbow table attacks.
 996                     byte[] encryptionPasswordWithSaltByteArray = new byte[encryptionPasswordByteArray.length + saltByteArray.length];
 997                     System.arraycopy(encryptionPasswordByteArray, 0, encryptionPasswordWithSaltByteArray, 0, encryptionPasswordByteArray.length);
 998                     System.arraycopy(saltByteArray, 0, encryptionPasswordWithSaltByteArray, encryptionPasswordByteArray.length, saltByteArray.length);
 999
1000                     // Get a SHA-512 message digest.
1001                     MessageDigest messageDigest = MessageDigest.getInstance("SHA-512");
1002
1003                     // Hash the salted encryption password.  Otherwise, any characters after the 32nd character in the password are ignored.
1004                     byte[] hashedEncryptionPasswordWithSaltByteArray = messageDigest.digest(encryptionPasswordWithSaltByteArray);
1005
1006                     // Truncate the encryption password byte array to 256 bits (32 bytes).
1007                     byte[] truncatedHashedEncryptionPasswordWithSaltByteArray = Arrays.copyOf(hashedEncryptionPasswordWithSaltByteArray, 32);
1008
1009                     // Create an AES secret key from the encryption password byte array.
1010                     SecretKeySpec secretKey = new SecretKeySpec(truncatedHashedEncryptionPasswordWithSaltByteArray, "AES");
1011
1012                     // 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.
1013                     Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
1014
1015                     // Set the GCM tag length to be 128 bits (the maximum) and apply the initialization vector.
1016                     GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, initializationVector);
1017
1018                     // Initialize the cipher.
1019                     cipher.init(Cipher.DECRYPT_MODE, secretKey, gcmParameterSpec);
1020
1021                     // Create a cipher input stream.
1022                     CipherInputStream cipherInputStream = new CipherInputStream(encryptedImportFileInputStream, cipher);
1023
1024                     // 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.
1025                     int numberOfBytesRead;
1026                     byte[] decryptedBytes = new byte[16];
1027
1028                     // 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.
1029                     while ((numberOfBytesRead = cipherInputStream.read(decryptedBytes)) != -1) {
1030                         // Write the data to the unencrypted import file output stream.
1031                         unencryptedImportFileOutputStream.write(decryptedBytes, 0, numberOfBytesRead);
1032                     }
1033
1034                     // Close the streams.
1035                     unencryptedImportFileOutputStream.flush();
1036                     unencryptedImportFileOutputStream.close();
1037                     cipherInputStream.close();
1038                     encryptedImportFileInputStream.close();
1039
1040                     // Wipe the encryption data from memory.
1041                     //noinspection UnusedAssignment
1042                     encryptionPasswordString = "";
1043                     Arrays.fill(saltByteArray, (byte) 0);
1044                     Arrays.fill(initializationVector, (byte) 0);
1045                     Arrays.fill(encryptionPasswordByteArray, (byte) 0);
1046                     Arrays.fill(encryptionPasswordWithSaltByteArray, (byte) 0);
1047                     Arrays.fill(hashedEncryptionPasswordWithSaltByteArray, (byte) 0);
1048                     Arrays.fill(truncatedHashedEncryptionPasswordWithSaltByteArray, (byte) 0);
1049                     Arrays.fill(decryptedBytes, (byte) 0);
1050
1051                     // Import the unencrypted database from the private location.
1052                     importStatus = importExportDatabaseHelper.importUnencrypted(temporaryUnencryptedImportFile, this);
1053
1054                     // Delete the temporary unencrypted import file.
1055                     //noinspection ResultOfMethodCallIgnored
1056                     temporaryUnencryptedImportFile.delete();
1057                 } catch (Exception exception) {
1058                     importStatus = exception.toString();
1059                 }
1060                 break;
1061
1062             case OPENPGP_ENCRYPTION:
1063                 try {
1064                     // Create an decryption intent for OpenKeychain.
1065                     Intent openKeychainDecryptIntent = new Intent("org.sufficientlysecure.keychain.action.DECRYPT_DATA");
1066
1067                     // Include the URI to be decrypted.
1068                     openKeychainDecryptIntent.setData(FileProvider.getUriForFile(this, getString(R.string.file_provider), importFile));
1069
1070                     // Allow OpenKeychain to read the file URI.
1071                     openKeychainDecryptIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
1072
1073                     // Send the intent to the OpenKeychain package.
1074                     openKeychainDecryptIntent.setPackage("org.sufficientlysecure.keychain");
1075
1076                     // Make it so.
1077                     startActivity(openKeychainDecryptIntent);
1078                 } catch (IllegalArgumentException exception) {  // The file import location is not valid.
1079                     // Display a snack bar with the import error.
1080                     Snackbar.make(fileNameEditText, getString(R.string.import_failed) + "  " + exception.toString(), Snackbar.LENGTH_INDEFINITE).show();
1081                 }
1082                 break;
1083         }
1084
1085         // Respond to the import disposition.
1086         if (importStatus.equals(ImportExportDatabaseHelper.IMPORT_SUCCESSFUL)) {  // The import was successful.
1087             // Create an intent to restart Privacy Browser.
1088             Intent restartIntent = getParentActivityIntent();
1089
1090             // Assert that the intent is not null to remove the lint error below.
1091             assert restartIntent != null;
1092
1093             // `Intent.FLAG_ACTIVITY_CLEAR_TASK` removes all activities from the stack.  It requires `Intent.FLAG_ACTIVITY_NEW_TASK`.
1094             restartIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
1095
1096             // Create a restart handler.
1097             Handler restartHandler = new Handler();
1098
1099             // Create a restart runnable.
1100             Runnable restartRunnable =  () -> {
1101                 // Restart Privacy Browser.
1102                 startActivity(restartIntent);
1103
1104                 // Kill this instance of Privacy Browser.  Otherwise, the app exhibits sporadic behavior after the restart.
1105                 System.exit(0);
1106             };
1107
1108             // Restart Privacy Browser after 150 milliseconds to allow enough time for the preferences to be saved.
1109             restartHandler.postDelayed(restartRunnable, 150);
1110
1111         } else if (!(encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION)){  // The import was not successful.
1112             // Display a snack bar with the import error.
1113             Snackbar.make(fileNameEditText, getString(R.string.import_failed) + "  " + importStatus, Snackbar.LENGTH_INDEFINITE).show();
1114         }
1115     }
1116 }