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     // Define 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     // Define the activity result constants.
  88     private final int BROWSE_RESULT_CODE = 0;
  89     private final int OPENPGP_EXPORT_RESULT_CODE = 1;
  90
  91     // Define the saved instance state constants.
  92     private final String PASSWORD_ENCRYPTED_TEXTINPUTLAYOUT_VISIBILITY = "password_encrypted_textinputlayout_visibility";
  93     private final String KITKAT_PASSWORD_ENCRYPTED_TEXTVIEW_VISIBILITY = "kitkat_password_encrypted_textview_visibility";
  94     private final String OPEN_KEYCHAIN_REQUIRED_TEXTVIEW_VISIBILITY = "open_keychain_required_textview_visibility";
  95     private final String FILE_LOCATION_CARD_VIEW = "file_location_card_view";
  96     private final String FILE_NAME_LINEARLAYOUT_VISIBILITY = "file_name_linearlayout_visibility";
  97     private final String FILE_DOES_NOT_EXIST_TEXTVIEW_VISIBILITY = "file_does_not_exist_textview_visibility";
  98     private final String FILE_EXISTS_WARNING_TEXTVIEW_VISIBILITY = "file_exists_warning_textview_visibility";
  99     private final String OPEN_KEYCHAIN_IMPORT_INSTRUCTIONS_TEXTVIEW_VISIBILITY = "open_keychain_import_instructions_textview_visibility";
 100     private final String IMPORT_EXPORT_BUTTON_VISIBILITY = "import_export_button_visibility";
 101     private final String FILE_NAME_TEXT = "file_name_text";
 102     private final String IMPORT_EXPORT_BUTTON_TEXT = "import_export_button_text";
 103
 104     // Define the class views.
 105     TextInputLayout passwordEncryptionTextInputLayout;
 106     TextView kitKatPasswordEncryptionTextView;
 107     TextView openKeychainRequiredTextView;
 108     CardView fileLocationCardView;
 109     LinearLayout fileNameLinearLayout;
 110     EditText fileNameEditText;
 111     TextView fileDoesNotExistTextView;
 112     TextView fileExistsWarningTextView;
 113     TextView openKeychainImportInstructionsTextView;
 114     Button importExportButton;
 115
 116     // Define the class variables.
 117     private boolean openKeychainInstalled;
 118
 119     @Override
 120     public void onCreate(Bundle savedInstanceState) {
 121         // Get a handle for the shared preferences.
 122         SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
 123
 124         // Get the screenshot preference.
 125         boolean allowScreenshots = sharedPreferences.getBoolean("allow_screenshots", false);
 126
 127         // Disable screenshots if not allowed.
 128         if (!allowScreenshots) {
 129             getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);
 130         }
 131
 132         // Set the theme.
 133         setTheme(R.style.PrivacyBrowser);
 134
 135         // Run the default commands.
 136         super.onCreate(savedInstanceState);
 137
 138         // Set the content view.
 139         setContentView(R.layout.import_export_coordinatorlayout);
 140
 141         // Set the support action bar.
 142         Toolbar toolbar = findViewById(R.id.import_export_toolbar);
 143         setSupportActionBar(toolbar);
 144
 145         // Get a handle for the action bar.
 146         ActionBar actionBar = getSupportActionBar();
 147
 148         // Remove the incorrect lint warning that the action bar might be null.
 149         assert actionBar != null;
 150
 151         // Display the home arrow on the support action bar.
 152         actionBar.setDisplayHomeAsUpEnabled(true);
 153
 154         // Find out if the system is running KitKat
 155         boolean runningKitKat = (Build.VERSION.SDK_INT == 19);
 156
 157         // Find out if OpenKeychain is installed.
 158         try {
 159             openKeychainInstalled = !getPackageManager().getPackageInfo("org.sufficientlysecure.keychain", 0).versionName.isEmpty();
 160         } catch (PackageManager.NameNotFoundException exception) {
 161             openKeychainInstalled = false;
 162         }
 163
 164         // Get handles for the views that need to be modified.
 165         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 166         passwordEncryptionTextInputLayout = findViewById(R.id.password_encryption_textinputlayout);
 167         EditText encryptionPasswordEditText = findViewById(R.id.password_encryption_edittext);
 168         kitKatPasswordEncryptionTextView = findViewById(R.id.kitkat_password_encryption_textview);
 169         openKeychainRequiredTextView = findViewById(R.id.openkeychain_required_textview);
 170         fileLocationCardView = findViewById(R.id.file_location_cardview);
 171         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 172         RadioButton exportRadioButton = findViewById(R.id.export_radiobutton);
 173         fileNameLinearLayout = findViewById(R.id.file_name_linearlayout);
 174         fileNameEditText = findViewById(R.id.file_name_edittext);
 175         fileDoesNotExistTextView = findViewById(R.id.file_does_not_exist_textview);
 176         fileExistsWarningTextView = findViewById(R.id.file_exists_warning_textview);
 177         openKeychainImportInstructionsTextView = findViewById(R.id.openkeychain_import_instructions_textview);
 178         importExportButton = findViewById(R.id.import_export_button);
 179         TextView storagePermissionTextView = findViewById(R.id.import_export_storage_permission_textview);
 180
 181         // Create an array adapter for the spinner.
 182         ArrayAdapter<CharSequence> encryptionArrayAdapter = ArrayAdapter.createFromResource(this, R.array.encryption_type, R.layout.spinner_item);
 183
 184         // Set the drop down view resource on the spinner.
 185         encryptionArrayAdapter.setDropDownViewResource(R.layout.spinner_dropdown_items);
 186
 187         // Set the array adapter for the spinner.
 188         encryptionSpinner.setAdapter(encryptionArrayAdapter);
 189
 190         // Instantiate the download location helper.
 191         DownloadLocationHelper downloadLocationHelper = new DownloadLocationHelper();
 192
 193         // Get the default file path.
 194         String defaultFilePath = downloadLocationHelper.getDownloadLocation(this) + "/" + getString(R.string.settings_pbs);
 195
 196         // Set the other default file paths.
 197         String defaultPasswordEncryptionFilePath = defaultFilePath + ".aes";
 198         String defaultPgpFilePath = defaultFilePath + ".pgp";
 199
 200         // Set the default file path.
 201         fileNameEditText.setText(defaultFilePath);
 202
 203         // Hide the storage permission text view if the permission has already been granted.
 204         if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
 205             storagePermissionTextView.setVisibility(View.GONE);
 206         }
 207
 208         // Update the UI when the spinner changes.
 209         encryptionSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
 210             @Override
 211             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
 212                 switch (position) {
 213                     case NO_ENCRYPTION:
 214                         // Hide the unneeded layout items.
 215                         passwordEncryptionTextInputLayout.setVisibility(View.GONE);
 216                         kitKatPasswordEncryptionTextView.setVisibility(View.GONE);
 217                         openKeychainRequiredTextView.setVisibility(View.GONE);
 218                         openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 219
 220                         // Show the file location card.
 221                         fileLocationCardView.setVisibility(View.VISIBLE);
 222
 223                         // Show the file name linear layout if either import or export is checked.
 224                         if (importRadioButton.isChecked() || exportRadioButton.isChecked()) {
 225                             fileNameLinearLayout.setVisibility(View.VISIBLE);
 226                         }
 227
 228                         // Reset the text of the import button, which may have been changed to `Decrypt`.
 229                         if (importRadioButton.isChecked()) {
 230                             importExportButton.setText(R.string.import_button);
 231                         }
 232
 233                         // Reset the default file path.
 234                         fileNameEditText.setText(defaultFilePath);
 235                         break;
 236
 237                     case PASSWORD_ENCRYPTION:
 238                         if (runningKitKat) {
 239                             // Show the KitKat password encryption message.
 240                             kitKatPasswordEncryptionTextView.setVisibility(View.VISIBLE);
 241
 242                             // Hide the OpenPGP required text view and the file location card.
 243                             openKeychainRequiredTextView.setVisibility(View.GONE);
 244                             fileLocationCardView.setVisibility(View.GONE);
 245                         } else {
 246                             // Hide the OpenPGP layout items.
 247                             openKeychainRequiredTextView.setVisibility(View.GONE);
 248                             openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 249
 250                             // Show the password encryption layout items.
 251                             passwordEncryptionTextInputLayout.setVisibility(View.VISIBLE);
 252
 253                             // Show the file location card.
 254                             fileLocationCardView.setVisibility(View.VISIBLE);
 255
 256                             // Show the file name linear layout if either import or export is checked.
 257                             if (importRadioButton.isChecked() || exportRadioButton.isChecked()) {
 258                                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 259                             }
 260
 261                             // Reset the text of the import button, which may have been changed to `Decrypt`.
 262                             if (importRadioButton.isChecked()) {
 263                                 importExportButton.setText(R.string.import_button);
 264                             }
 265
 266                             // Update the default file path.
 267                             fileNameEditText.setText(defaultPasswordEncryptionFilePath);
 268                         }
 269                         break;
 270
 271                     case OPENPGP_ENCRYPTION:
 272                         // Hide the password encryption layout items.
 273                         passwordEncryptionTextInputLayout.setVisibility(View.GONE);
 274                         kitKatPasswordEncryptionTextView.setVisibility(View.GONE);
 275
 276                         // Updated items based on the installation status of OpenKeychain.
 277                         if (openKeychainInstalled) {  // OpenKeychain is installed.
 278                             // Update the default file path.
 279                             fileNameEditText.setText(defaultPgpFilePath);
 280
 281                             // Show the file location card.
 282                             fileLocationCardView.setVisibility(View.VISIBLE);
 283
 284                             if (importRadioButton.isChecked()) {
 285                                 // Show the file name linear layout and the OpenKeychain import instructions.
 286                                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 287                                 openKeychainImportInstructionsTextView.setVisibility(View.VISIBLE);
 288
 289                                 // Set the text of the import button to be `Decrypt`.
 290                                 importExportButton.setText(R.string.decrypt);
 291                             } else if (exportRadioButton.isChecked()) {
 292                                 // Hide the file name linear layout and the OpenKeychain import instructions.
 293                                 fileNameLinearLayout.setVisibility(View.GONE);
 294                                 openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 295                             }
 296                         } else {  // OpenKeychain is not installed.
 297                             // Show the OpenPGP required layout item.
 298                             openKeychainRequiredTextView.setVisibility(View.VISIBLE);
 299
 300                             // Hide the file location card.
 301                             fileLocationCardView.setVisibility(View.GONE);
 302                         }
 303                         break;
 304                 }
 305             }
 306
 307             @Override
 308             public void onNothingSelected(AdapterView<?> parent) {
 309
 310             }
 311         });
 312
 313         // Update the status of the import/export button when the password changes.
 314         encryptionPasswordEditText.addTextChangedListener(new TextWatcher() {
 315             @Override
 316             public void beforeTextChanged(CharSequence s, int start, int count, int after) {
 317                 // Do nothing.
 318             }
 319
 320             @Override
 321             public void onTextChanged(CharSequence s, int start, int before, int count) {
 322                 // Do nothing.
 323             }
 324
 325             @Override
 326             public void afterTextChanged(Editable s) {
 327                 // Get the current file name.
 328                 String fileNameString = fileNameEditText.getText().toString();
 329
 330                 // Convert the file name string to a file.
 331                 File file = new File(fileNameString);
 332
 333                 // Update the import/export button.
 334                 if (importRadioButton.isChecked()) {  // The import radio button is checked.
 335                     // Enable the import button if the file and the password exists.
 336                     importExportButton.setEnabled(file.exists() && !encryptionPasswordEditText.getText().toString().isEmpty());
 337                 } else if (exportRadioButton.isChecked()) {  // The export radio button is checked.
 338                     // Enable the export button if the file string and the password exists.
 339                     importExportButton.setEnabled(!fileNameString.isEmpty() && !encryptionPasswordEditText.getText().toString().isEmpty());
 340                 }
 341             }
 342         });
 343
 344         // Update the UI when the file name EditText changes.
 345         fileNameEditText.addTextChangedListener(new TextWatcher() {
 346             @Override
 347             public void beforeTextChanged(CharSequence s, int start, int count, int after) {
 348                 // Do nothing.
 349             }
 350
 351             @Override
 352             public void onTextChanged(CharSequence s, int start, int before, int count) {
 353                 // Do nothing.
 354             }
 355
 356             @Override
 357             public void afterTextChanged(Editable s) {
 358                 // Get the current file name.
 359                 String fileNameString = fileNameEditText.getText().toString();
 360
 361                 // Convert the file name string to a file.
 362                 File file = new File(fileNameString);
 363
 364                 // Adjust the UI according to the encryption spinner position.
 365                 switch (encryptionSpinner.getSelectedItemPosition()) {
 366                     case NO_ENCRYPTION:
 367                         // Determine if import or export is checked.
 368                         if (exportRadioButton.isChecked()) {  // The export radio button is checked.
 369                             // Hide the file does not exist text view.
 370                             fileDoesNotExistTextView.setVisibility(View.GONE);
 371
 372                             // Display a warning if the file already exists.
 373                             if (file.exists()) {
 374                                 fileExistsWarningTextView.setVisibility(View.VISIBLE);
 375                             } else {
 376                                 fileExistsWarningTextView.setVisibility(View.GONE);
 377                             }
 378
 379                             // Enable the export button if the file name is populated.
 380                             importExportButton.setEnabled(!fileNameString.isEmpty());
 381                         } else if (importRadioButton.isChecked()) {  // The import radio button is checked.
 382                             // Hide the file exists warning text view.
 383                             fileExistsWarningTextView.setVisibility(View.GONE);
 384
 385                             // Check if the file exists.
 386                             if (file.exists()) {  // The file exists.
 387                                 // Hide the notification that the file does not exist.
 388                                 fileDoesNotExistTextView.setVisibility(View.GONE);
 389
 390                                 // Enable the import button.
 391                                 importExportButton.setEnabled(true);
 392                             } else {  // The file does not exist.
 393                                 // Show a notification that the file does not exist.
 394                                 fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 395
 396                                 // Disable the import button.
 397                                 importExportButton.setEnabled(false);
 398                             }
 399                         } else {  // Neither radio button is checked.
 400                             // Hide the file notification text views.
 401                             fileExistsWarningTextView.setVisibility(View.GONE);
 402                             fileDoesNotExistTextView.setVisibility(View.GONE);
 403                         }
 404                         break;
 405
 406                     case PASSWORD_ENCRYPTION:
 407                         // Determine if import or export is checked.
 408                         if (exportRadioButton.isChecked()) {  // The export radio button is checked.
 409                             // Hide the notification that the file does not exist.
 410                             fileDoesNotExistTextView.setVisibility(View.GONE);
 411
 412                             // Display a warning if the file already exists.
 413                             if (file.exists()) {
 414                                 fileExistsWarningTextView.setVisibility(View.VISIBLE);
 415                             } else {
 416                                 fileExistsWarningTextView.setVisibility(View.GONE);
 417                             }
 418
 419                             // Enable the export button if the file name and the password are populated.
 420                             importExportButton.setEnabled(!fileNameString.isEmpty() && !encryptionPasswordEditText.getText().toString().isEmpty());
 421                         } else if (importRadioButton.isChecked()) {  // The import radio button is checked.
 422                             // Hide the file exists warning text view.
 423                             fileExistsWarningTextView.setVisibility(View.GONE);
 424
 425                             // Check if the file exists.
 426                             if (file.exists()) {  // The file exists.
 427                                 // Hide the notification that the file does not exist.
 428                                 fileDoesNotExistTextView.setVisibility(View.GONE);
 429
 430                                 // Enable the import button if the password is populated.
 431                                 importExportButton.setEnabled(!encryptionPasswordEditText.getText().toString().isEmpty());
 432                             } else {  // The file does not exist.
 433                                 // Show a notification that the file does not exist.
 434                                 fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 435
 436                                 // Disable the import button.
 437                                 importExportButton.setEnabled(false);
 438                             }
 439                         } else {  // Neither radio button is checked.
 440                             // Hide the file notification text views.
 441                             fileExistsWarningTextView.setVisibility(View.GONE);
 442                             fileDoesNotExistTextView.setVisibility(View.GONE);
 443                         }
 444                         break;
 445
 446                     case OPENPGP_ENCRYPTION:
 447                         // Hide the file exists warning text view.
 448                         fileExistsWarningTextView.setVisibility(View.GONE);
 449
 450                         if (importRadioButton.isChecked()) {  // The import radio button is checked.
 451                             if (file.exists()) {  // The file exists.
 452                                 // Hide the notification that the file does not exist.
 453                                 fileDoesNotExistTextView.setVisibility(View.GONE);
 454
 455                                 // Enable the import button if OpenKeychain is installed.
 456                                 importExportButton.setEnabled(openKeychainInstalled);
 457                             } else {  // The file does not exist.
 458                                 // Show the notification that the file does not exist.
 459                                 fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 460
 461                                 // Disable the import button.
 462                                 importExportButton.setEnabled(false);
 463                             }
 464                         } else if (exportRadioButton.isChecked()){  // The export radio button is checked.
 465                             // Hide the notification that the file does not exist.
 466                             fileDoesNotExistTextView.setVisibility(View.GONE);
 467
 468                             // Enable the export button.
 469                             importExportButton.setEnabled(true);
 470                         } else {  // Neither radio button is checked.
 471                             // Hide the notification that the file does not exist.
 472                             fileDoesNotExistTextView.setVisibility(View.GONE);
 473                         }
 474                         break;
 475                 }
 476             }
 477         });
 478
 479         // Check to see if the activity has been restarted.
 480         if (savedInstanceState == null) {  // The app has not been restarted.
 481             // Initially hide the unneeded views.
 482             passwordEncryptionTextInputLayout.setVisibility(View.GONE);
 483             kitKatPasswordEncryptionTextView.setVisibility(View.GONE);
 484             openKeychainRequiredTextView.setVisibility(View.GONE);
 485             fileNameLinearLayout.setVisibility(View.GONE);
 486             fileDoesNotExistTextView.setVisibility(View.GONE);
 487             fileExistsWarningTextView.setVisibility(View.GONE);
 488             openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 489             importExportButton.setVisibility(View.GONE);
 490         } else {  // The app has been restarted.
 491             // Restore the visibility of the views.
 492             passwordEncryptionTextInputLayout.setVisibility(savedInstanceState.getInt(PASSWORD_ENCRYPTED_TEXTINPUTLAYOUT_VISIBILITY));
 493             kitKatPasswordEncryptionTextView.setVisibility(savedInstanceState.getInt(KITKAT_PASSWORD_ENCRYPTED_TEXTVIEW_VISIBILITY));
 494             openKeychainRequiredTextView.setVisibility(savedInstanceState.getInt(OPEN_KEYCHAIN_REQUIRED_TEXTVIEW_VISIBILITY));
 495             fileLocationCardView.setVisibility(savedInstanceState.getInt(FILE_LOCATION_CARD_VIEW));
 496             fileNameLinearLayout.setVisibility(savedInstanceState.getInt(FILE_NAME_LINEARLAYOUT_VISIBILITY));
 497             fileDoesNotExistTextView.setVisibility(savedInstanceState.getInt(FILE_DOES_NOT_EXIST_TEXTVIEW_VISIBILITY));
 498             fileExistsWarningTextView.setVisibility(savedInstanceState.getInt(FILE_EXISTS_WARNING_TEXTVIEW_VISIBILITY));
 499             openKeychainImportInstructionsTextView.setVisibility(savedInstanceState.getInt(OPEN_KEYCHAIN_IMPORT_INSTRUCTIONS_TEXTVIEW_VISIBILITY));
 500             importExportButton.setVisibility(savedInstanceState.getInt(IMPORT_EXPORT_BUTTON_VISIBILITY));
 501
 502             // Restore the text.
 503             fileNameEditText.post(() -> fileNameEditText.setText(savedInstanceState.getString(FILE_NAME_TEXT)));
 504             importExportButton.setText(savedInstanceState.getString(IMPORT_EXPORT_BUTTON_TEXT));
 505         }
 506     }
 507
 508     @Override
 509     public void onSaveInstanceState (@NonNull Bundle savedInstanceState) {
 510         // Run the default commands.
 511         super.onSaveInstanceState(savedInstanceState);
 512
 513         // Save the visibility of the views.
 514         savedInstanceState.putInt(PASSWORD_ENCRYPTED_TEXTINPUTLAYOUT_VISIBILITY, passwordEncryptionTextInputLayout.getVisibility());
 515         savedInstanceState.putInt(KITKAT_PASSWORD_ENCRYPTED_TEXTVIEW_VISIBILITY, kitKatPasswordEncryptionTextView.getVisibility());
 516         savedInstanceState.putInt(OPEN_KEYCHAIN_REQUIRED_TEXTVIEW_VISIBILITY, openKeychainRequiredTextView.getVisibility());
 517         savedInstanceState.putInt(FILE_LOCATION_CARD_VIEW, fileLocationCardView.getVisibility());
 518         savedInstanceState.putInt(FILE_NAME_LINEARLAYOUT_VISIBILITY, fileNameLinearLayout.getVisibility());
 519         savedInstanceState.putInt(FILE_DOES_NOT_EXIST_TEXTVIEW_VISIBILITY, fileDoesNotExistTextView.getVisibility());
 520         savedInstanceState.putInt(FILE_EXISTS_WARNING_TEXTVIEW_VISIBILITY, fileExistsWarningTextView.getVisibility());
 521         savedInstanceState.putInt(OPEN_KEYCHAIN_IMPORT_INSTRUCTIONS_TEXTVIEW_VISIBILITY, openKeychainImportInstructionsTextView.getVisibility());
 522         savedInstanceState.putInt(IMPORT_EXPORT_BUTTON_VISIBILITY, importExportButton.getVisibility());
 523
 524         // Save the text.
 525         savedInstanceState.putString(FILE_NAME_TEXT, fileNameEditText.getText().toString());
 526         savedInstanceState.putString(IMPORT_EXPORT_BUTTON_TEXT, importExportButton.getText().toString());
 527     }
 528
 529     public void onClickRadioButton(View view) {
 530         // Get handles for the views.
 531         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 532         LinearLayout fileNameLinearLayout = findViewById(R.id.file_name_linearlayout);
 533         EditText passwordEncryptionEditText = findViewById(R.id.password_encryption_edittext);
 534         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 535         TextView fileDoesNotExistTextView = findViewById(R.id.file_does_not_exist_textview);
 536         TextView fileExistsWarningTextView = findViewById(R.id.file_exists_warning_textview);
 537         TextView openKeychainImportInstructionTextView = findViewById(R.id.openkeychain_import_instructions_textview);
 538         Button importExportButton = findViewById(R.id.import_export_button);
 539
 540         // Get the current file name.
 541         String fileNameString = fileNameEditText.getText().toString();
 542
 543         // Convert the file name string to a file.
 544         File file = new File(fileNameString);
 545
 546         // Check to see if import or export was selected.
 547         switch (view.getId()) {
 548             case R.id.import_radiobutton:
 549                 // Check to see if OpenPGP encryption is selected.
 550                 if (encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) {  // OpenPGP encryption selected.
 551                     // Show the OpenKeychain import instructions.
 552                     openKeychainImportInstructionTextView.setVisibility(View.VISIBLE);
 553
 554                     // Set the text on the import/export button to be `Decrypt`.
 555                     importExportButton.setText(R.string.decrypt);
 556                 } else {  // OpenPGP encryption not selected.
 557                     // Hide the OpenKeychain import instructions.
 558                     openKeychainImportInstructionTextView.setVisibility(View.GONE);
 559
 560                     // Set the text on the import/export button to be `Import`.
 561                     importExportButton.setText(R.string.import_button);
 562                 }
 563
 564                 // Hide the file exists warning text view.
 565                 fileExistsWarningTextView.setVisibility(View.GONE);
 566
 567                 // Display the file name views.
 568                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 569                 importExportButton.setVisibility(View.VISIBLE);
 570
 571                 // Check to see if the file exists.
 572                 if (file.exists()) {  // The file exists.
 573                     // Hide the notification that the file does not exist.
 574                     fileDoesNotExistTextView.setVisibility(View.GONE);
 575
 576                     // Check to see if password encryption is selected.
 577                     if (encryptionSpinner.getSelectedItemPosition() == PASSWORD_ENCRYPTION) {  // Password encryption is selected.
 578                         // Enable the import button if the encryption password is populated.
 579                         importExportButton.setEnabled(!passwordEncryptionEditText.getText().toString().isEmpty());
 580                     } else {  // Password encryption is not selected.
 581                         // Enable the import/decrypt button.
 582                         importExportButton.setEnabled(true);
 583                     }
 584                 } else {  // The file does not exist.
 585                     // Show the notification that the file does not exist.
 586                     fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 587
 588                     // Disable the import/decrypt button.
 589                     importExportButton.setEnabled(false);
 590                 }
 591                 break;
 592
 593             case R.id.export_radiobutton:
 594                 // Hide the OpenKeychain import instructions.
 595                 openKeychainImportInstructionTextView.setVisibility(View.GONE);
 596
 597                 // Set the text on the import/export button to be `Export`.
 598                 importExportButton.setText(R.string.export);
 599
 600                 // Show the import/export button.
 601                 importExportButton.setVisibility(View.VISIBLE);
 602
 603                 // Check to see if OpenPGP encryption is selected.
 604                 if (encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) {  // OpenPGP encryption is selected.
 605                     // Hide the file name views.
 606                     fileNameLinearLayout.setVisibility(View.GONE);
 607                     fileDoesNotExistTextView.setVisibility(View.GONE);
 608                     fileExistsWarningTextView.setVisibility(View.GONE);
 609
 610                     // Enable the export button.
 611                     importExportButton.setEnabled(true);
 612                 } else {  // OpenPGP encryption is not selected.
 613                     // Show the file name view.
 614                     fileNameLinearLayout.setVisibility(View.VISIBLE);
 615
 616                     // Hide the notification that the file name does not exist.
 617                     fileDoesNotExistTextView.setVisibility(View.GONE);
 618
 619                     // Display a warning if the file already exists.
 620                     if (file.exists()) {
 621                         fileExistsWarningTextView.setVisibility(View.VISIBLE);
 622                     } else {
 623                         fileExistsWarningTextView.setVisibility(View.GONE);
 624                     }
 625
 626                     // Check the encryption type.
 627                     if (encryptionSpinner.getSelectedItemPosition() == NO_ENCRYPTION) {  // No encryption is selected.
 628                         // Enable the export button if the file name is populated.
 629                         importExportButton.setEnabled(!fileNameString.isEmpty());
 630                     } else {  // Password encryption is selected.
 631                         // Enable the export button if the file name and the password are populated.
 632                         importExportButton.setEnabled(!fileNameString.isEmpty() && !passwordEncryptionEditText.getText().toString().isEmpty());
 633                     }
 634                 }
 635                 break;
 636         }
 637     }
 638
 639     public void browse(View view) {
 640         // Get a handle for the views.
 641         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 642         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 643
 644         // Check to see if import or export is selected.
 645         if (importRadioButton.isChecked()) {  // Import is selected.
 646             // Create the file picker intent.
 647             Intent importBrowseIntent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
 648
 649             // Set the intent MIME type to include all files so that everything is visible.
 650             importBrowseIntent.setType("*/*");
 651
 652             // Set the initial directory if the minimum API >= 26.
 653             if (Build.VERSION.SDK_INT >= 26) {
 654                 importBrowseIntent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, Environment.getExternalStorageDirectory());
 655             }
 656
 657             // Request a file that can be opened.
 658             importBrowseIntent.addCategory(Intent.CATEGORY_OPENABLE);
 659
 660             // Launch the file picker.
 661             startActivityForResult(importBrowseIntent, BROWSE_RESULT_CODE);
 662         } else {  // Export is selected
 663             // Create the file picker intent.
 664             Intent exportBrowseIntent = new Intent(Intent.ACTION_CREATE_DOCUMENT);
 665
 666             // Set the intent MIME type to include all files so that everything is visible.
 667             exportBrowseIntent.setType("*/*");
 668
 669             // Set the initial export file name according to the encryption type.
 670             if (encryptionSpinner.getSelectedItemPosition() == NO_ENCRYPTION) {  // No encryption is selected.
 671                 exportBrowseIntent.putExtra(Intent.EXTRA_TITLE, getString(R.string.settings_pbs));
 672             } else {  // Password encryption is selected.
 673                 exportBrowseIntent.putExtra(Intent.EXTRA_TITLE, getString(R.string.settings_pbs) + ".aes");
 674             }
 675
 676             // Set the initial directory if the minimum API >= 26.
 677             if (Build.VERSION.SDK_INT >= 26) {
 678                 exportBrowseIntent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, Environment.getExternalStorageDirectory());
 679             }
 680
 681             // Request a file that can be opened.
 682             exportBrowseIntent.addCategory(Intent.CATEGORY_OPENABLE);
 683
 684             // Launch the file picker.
 685             startActivityForResult(exportBrowseIntent, BROWSE_RESULT_CODE);
 686         }
 687     }
 688
 689     public void importExport(View view) {
 690         // Get a handle for the views.
 691         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 692         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 693         RadioButton exportRadioButton = findViewById(R.id.export_radiobutton);
 694
 695         // Check to see if the storage permission is needed.
 696         if ((encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) && exportRadioButton.isChecked()) {  // Permission not needed to export via OpenKeychain.
 697             // Export the settings.
 698             exportSettings();
 699         } else if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {  // The storage permission has been granted.
 700             // Check to see if import or export is selected.
 701             if (importRadioButton.isChecked()) {  // Import is selected.
 702                 // Import the settings.
 703                 importSettings();
 704             } else {  // Export is selected.
 705                 // Export the settings.
 706                 exportSettings();
 707             }
 708         } else {  // The storage permission has not been granted.
 709             // Get a handle for the file name EditText.
 710             EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 711
 712             // Get the file name string.
 713             String fileNameString = fileNameEditText.getText().toString();
 714
 715             // Get the external private directory `File`.
 716             File externalPrivateDirectoryFile = getExternalFilesDir(null);
 717
 718             // Remove the incorrect lint error below that the file might be null.
 719             assert externalPrivateDirectoryFile != null;
 720
 721             // Get the external private directory string.
 722             String externalPrivateDirectory = externalPrivateDirectoryFile.toString();
 723
 724             // Check to see if the file path is in the external private directory.
 725             if (fileNameString.startsWith(externalPrivateDirectory)) {  // The file path is in the external private directory.
 726                 // Check to see if import or export is selected.
 727                 if (importRadioButton.isChecked()) {  // Import is selected.
 728                     // Import the settings.
 729                     importSettings();
 730                 } else {  // Export is selected.
 731                     // Export the settings.
 732                     exportSettings();
 733                 }
 734             } else {  // The file path is in a public directory.
 735                 // Check if the user has previously denied the storage permission.
 736                 if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {  // Show a dialog explaining the request first.
 737                     // Instantiate the storage permission alert dialog.
 738                     DialogFragment storagePermissionDialogFragment = StoragePermissionDialog.displayDialog(0);
 739
 740                     // Show the storage permission alert dialog.  The permission will be requested when the dialog is closed.
 741                     storagePermissionDialogFragment.show(getSupportFragmentManager(), getString(R.string.storage_permission));
 742                 } else {  // Show the permission request directly.
 743                     // Request the storage permission.  The export will be run when it finishes.
 744                     ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);
 745                 }
 746             }
 747         }
 748     }
 749
 750     @Override
 751     public void onCloseStoragePermissionDialog(int type) {
 752         // Request the write external storage permission.  The import/export will be run when it finishes.
 753         ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);
 754     }
 755
 756     @Override
 757     public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
 758         // Get a handle for the import radiobutton.
 759         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 760
 761         // Check to see if the storage permission was granted.  If the dialog was canceled the grant results will be empty.
 762         if ((grantResults.length > 0) && (grantResults[0] == PackageManager.PERMISSION_GRANTED)) {  // The storage permission was granted.
 763             // Run the import or export methods according to which radio button is selected.
 764             if (importRadioButton.isChecked()) {  // Import is selected.
 765                 // Import the settings.
 766                 importSettings();
 767             } else {  // Export is selected.
 768                 // Export the settings.
 769                 exportSettings();
 770             }
 771         } else {  // The storage permission was not granted.
 772             // Display an error snackbar.
 773             Snackbar.make(importRadioButton, getString(R.string.cannot_use_location), Snackbar.LENGTH_LONG).show();
 774         }
 775     }
 776
 777     @Override
 778     public void onActivityResult(int requestCode, int resultCode, Intent intent) {
 779         // Run the default commands.
 780         super.onActivityResult(requestCode, resultCode, intent);
 781
 782         switch (requestCode) {
 783             case (BROWSE_RESULT_CODE):
 784                 // Don't do anything if the user pressed back from the file picker.
 785                 if (resultCode == Activity.RESULT_OK) {
 786                     // Get a handle for the views.
 787                     EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 788                     TextView fileExistsWarningTextView = findViewById(R.id.file_exists_warning_textview);
 789
 790                     // Instantiate the file name helper.
 791                     FileNameHelper fileNameHelper = new FileNameHelper();
 792
 793                     // Get the file path URI from the intent.
 794                     Uri filePathUri = intent.getData();
 795
 796                     // Use the file path from the intent if it exists.
 797                     if (filePathUri != null) {
 798                         // Convert the file name URI to a file name path.
 799                         String fileNamePath = fileNameHelper.convertUriToFileNamePath(filePathUri);
 800
 801                         // Set the file name path as the text of the file name edit text.
 802                         fileNameEditText.setText(fileNamePath);
 803
 804                         // Hide the file exists warning text view, because the file picker will have just created a file if export was selected.
 805                         fileExistsWarningTextView.setVisibility(View.GONE);
 806                     }
 807                 }
 808                 break;
 809
 810             case OPENPGP_EXPORT_RESULT_CODE:
 811                 // Get the temporary unencrypted export file.
 812                 File temporaryUnencryptedExportFile = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.settings_pbs));
 813
 814                 // Delete the temporary unencrypted export file if it exists.
 815                 if (temporaryUnencryptedExportFile.exists()) {
 816                     //noinspection ResultOfMethodCallIgnored
 817                     temporaryUnencryptedExportFile.delete();
 818                 }
 819                 break;
 820         }
 821     }
 822
 823     private void exportSettings() {
 824         // Get a handle for the views.
 825         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 826         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 827
 828         // Instantiate the import export database helper.
 829         ImportExportDatabaseHelper importExportDatabaseHelper = new ImportExportDatabaseHelper();
 830
 831         // Get the export file string.
 832         String exportFileString = fileNameEditText.getText().toString();
 833
 834         // Get the export and temporary unencrypted export files.
 835         File exportFile = new File(exportFileString);
 836         File temporaryUnencryptedExportFile = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.settings_pbs));
 837
 838         // Create an export status string.
 839         String exportStatus;
 840
 841         // Export according to the encryption type.
 842         switch (encryptionSpinner.getSelectedItemPosition()) {
 843             case NO_ENCRYPTION:
 844                 // Export the unencrypted file.
 845                 exportStatus = importExportDatabaseHelper.exportUnencrypted(exportFile, this);
 846
 847                 // Show a disposition snackbar.
 848                 if (exportStatus.equals(ImportExportDatabaseHelper.EXPORT_SUCCESSFUL)) {
 849                     Snackbar.make(fileNameEditText, getString(R.string.export_successful), Snackbar.LENGTH_SHORT).show();
 850                 } else {
 851                     Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + exportStatus, Snackbar.LENGTH_INDEFINITE).show();
 852                 }
 853                 break;
 854
 855             case PASSWORD_ENCRYPTION:
 856                 // Create an unencrypted export in a private directory.
 857                 exportStatus = importExportDatabaseHelper.exportUnencrypted(temporaryUnencryptedExportFile, this);
 858
 859                 try {
 860                     // Create an unencrypted export file input stream.
 861                     FileInputStream unencryptedExportFileInputStream = new FileInputStream(temporaryUnencryptedExportFile);
 862
 863                     // Delete the encrypted export file if it exists.
 864                     if (exportFile.exists()) {
 865                         //noinspection ResultOfMethodCallIgnored
 866                         exportFile.delete();
 867                     }
 868
 869                     // Create an encrypted export file output stream.
 870                     FileOutputStream encryptedExportFileOutputStream = new FileOutputStream(exportFile);
 871
 872                     // Get a handle for the encryption password EditText.
 873                     EditText encryptionPasswordEditText = findViewById(R.id.password_encryption_edittext);
 874
 875                     // Get the encryption password.
 876                     String encryptionPasswordString = encryptionPasswordEditText.getText().toString();
 877
 878                     // Initialize a secure random number generator.
 879                     SecureRandom secureRandom = new SecureRandom();
 880
 881                     // Get a 256 bit (32 byte) random salt.
 882                     byte[] saltByteArray = new byte[32];
 883                     secureRandom.nextBytes(saltByteArray);
 884
 885                     // Convert the encryption password to a byte array.
 886                     byte[] encryptionPasswordByteArray = encryptionPasswordString.getBytes(StandardCharsets.UTF_8);
 887
 888                     // Append the salt to the encryption password byte array.  This protects against rainbow table attacks.
 889                     byte[] encryptionPasswordWithSaltByteArray = new byte[encryptionPasswordByteArray.length + saltByteArray.length];
 890                     System.arraycopy(encryptionPasswordByteArray, 0, encryptionPasswordWithSaltByteArray, 0, encryptionPasswordByteArray.length);
 891                     System.arraycopy(saltByteArray, 0, encryptionPasswordWithSaltByteArray, encryptionPasswordByteArray.length, saltByteArray.length);
 892
 893                     // Get a SHA-512 message digest.
 894                     MessageDigest messageDigest = MessageDigest.getInstance("SHA-512");
 895
 896                     // Hash the salted encryption password.  Otherwise, any characters after the 32nd character in the password are ignored.
 897                     byte[] hashedEncryptionPasswordWithSaltByteArray = messageDigest.digest(encryptionPasswordWithSaltByteArray);
 898
 899                     // Truncate the encryption password byte array to 256 bits (32 bytes).
 900                     byte[] truncatedHashedEncryptionPasswordWithSaltByteArray = Arrays.copyOf(hashedEncryptionPasswordWithSaltByteArray, 32);
 901
 902                     // Create an AES secret key from the encryption password byte array.
 903                     SecretKeySpec secretKey = new SecretKeySpec(truncatedHashedEncryptionPasswordWithSaltByteArray, "AES");
 904
 905                     // Generate a random 12 byte initialization vector.  According to NIST, a 12 byte initialization vector is more secure than a 16 byte one.
 906                     byte[] initializationVector = new byte[12];
 907                     secureRandom.nextBytes(initializationVector);
 908
 909                     // 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.
 910                     Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
 911
 912                     // Set the GCM tag length to be 128 bits (the maximum) and apply the initialization vector.
 913                     GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, initializationVector);
 914
 915                     // Initialize the cipher.
 916                     cipher.init(Cipher.ENCRYPT_MODE, secretKey, gcmParameterSpec);
 917
 918                     // Add the salt and the initialization vector to the export file.
 919                     encryptedExportFileOutputStream.write(saltByteArray);
 920                     encryptedExportFileOutputStream.write(initializationVector);
 921
 922                     // Create a cipher output stream.
 923                     CipherOutputStream cipherOutputStream = new CipherOutputStream(encryptedExportFileOutputStream, cipher);
 924
 925                     // 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.
 926                     int numberOfBytesRead;
 927                     byte[] encryptedBytes = new byte[16];
 928
 929                     // 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.
 930                     while ((numberOfBytesRead = unencryptedExportFileInputStream.read(encryptedBytes)) != -1) {
 931                         // Write the data to the cipher output stream.
 932                         cipherOutputStream.write(encryptedBytes, 0, numberOfBytesRead);
 933                     }
 934
 935                     // Close the streams.
 936                     cipherOutputStream.flush();
 937                     cipherOutputStream.close();
 938                     encryptedExportFileOutputStream.close();
 939                     unencryptedExportFileInputStream.close();
 940
 941                     // Wipe the encryption data from memory.
 942                     //noinspection UnusedAssignment
 943                     encryptionPasswordString = "";
 944                     Arrays.fill(saltByteArray, (byte) 0);
 945                     Arrays.fill(encryptionPasswordByteArray, (byte) 0);
 946                     Arrays.fill(encryptionPasswordWithSaltByteArray, (byte) 0);
 947                     Arrays.fill(hashedEncryptionPasswordWithSaltByteArray, (byte) 0);
 948                     Arrays.fill(truncatedHashedEncryptionPasswordWithSaltByteArray, (byte) 0);
 949                     Arrays.fill(initializationVector, (byte) 0);
 950                     Arrays.fill(encryptedBytes, (byte) 0);
 951
 952                     // Delete the temporary unencrypted export file.
 953                     //noinspection ResultOfMethodCallIgnored
 954                     temporaryUnencryptedExportFile.delete();
 955                 } catch (Exception exception) {
 956                     exportStatus = exception.toString();
 957                 }
 958
 959                 // Show a disposition snackbar.
 960                 if (exportStatus.equals(ImportExportDatabaseHelper.EXPORT_SUCCESSFUL)) {
 961                     Snackbar.make(fileNameEditText, getString(R.string.export_successful), Snackbar.LENGTH_SHORT).show();
 962                 } else {
 963                     Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + exportStatus, Snackbar.LENGTH_INDEFINITE).show();
 964                 }
 965                 break;
 966
 967             case OPENPGP_ENCRYPTION:
 968                 // Create an unencrypted export in the private location.
 969                 importExportDatabaseHelper.exportUnencrypted(temporaryUnencryptedExportFile, this);
 970
 971                 // Create an encryption intent for OpenKeychain.
 972                 Intent openKeychainEncryptIntent = new Intent("org.sufficientlysecure.keychain.action.ENCRYPT_DATA");
 973
 974                 // Include the temporary unencrypted export file URI.
 975                 openKeychainEncryptIntent.setData(FileProvider.getUriForFile(this, getString(R.string.file_provider), temporaryUnencryptedExportFile));
 976
 977                 // Allow OpenKeychain to read the file URI.
 978                 openKeychainEncryptIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
 979
 980                 // Send the intent to the OpenKeychain package.
 981                 openKeychainEncryptIntent.setPackage("org.sufficientlysecure.keychain");
 982
 983                 // Make it so.
 984                 startActivityForResult(openKeychainEncryptIntent, OPENPGP_EXPORT_RESULT_CODE);
 985                 break;
 986         }
 987
 988         // Add the file to the list of recent files.  This doesn't currently work, but maybe it will someday.
 989         MediaScannerConnection.scanFile(this, new String[] {exportFileString}, new String[] {"application/x-sqlite3"}, null);
 990     }
 991
 992     private void importSettings() {
 993         // Get a handle for the views.
 994         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 995         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 996
 997         // Instantiate the import export database helper.
 998         ImportExportDatabaseHelper importExportDatabaseHelper = new ImportExportDatabaseHelper();
 999
1000         // Get the import file.
1001         File importFile = new File(fileNameEditText.getText().toString());
1002
1003         // Initialize the import status string
1004         String importStatus = "";
1005
1006         // Import according to the encryption type.
1007         switch (encryptionSpinner.getSelectedItemPosition()) {
1008             case NO_ENCRYPTION:
1009                 // Import the unencrypted file.
1010                 importStatus = importExportDatabaseHelper.importUnencrypted(importFile, this);
1011                 break;
1012
1013             case PASSWORD_ENCRYPTION:
1014                 // Use a private temporary import location.
1015                 File temporaryUnencryptedImportFile = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.settings_pbs));
1016
1017                 try {
1018                     // Create an encrypted import file input stream.
1019                     FileInputStream encryptedImportFileInputStream = new FileInputStream(importFile);
1020
1021                     // Delete the temporary import file if it exists.
1022                     if (temporaryUnencryptedImportFile.exists()) {
1023                         //noinspection ResultOfMethodCallIgnored
1024                         temporaryUnencryptedImportFile.delete();
1025                     }
1026
1027                     // Create an unencrypted import file output stream.
1028                     FileOutputStream unencryptedImportFileOutputStream = new FileOutputStream(temporaryUnencryptedImportFile);
1029
1030                     // Get a handle for the encryption password EditText.
1031                     EditText encryptionPasswordEditText = findViewById(R.id.password_encryption_edittext);
1032
1033                     // Get the encryption password.
1034                     String encryptionPasswordString = encryptionPasswordEditText.getText().toString();
1035
1036                     // Get the salt from the beginning of the import file.
1037                     byte[] saltByteArray = new byte[32];
1038                     //noinspection ResultOfMethodCallIgnored
1039                     encryptedImportFileInputStream.read(saltByteArray);
1040
1041                     // Get the initialization vector from the import file.
1042                     byte[] initializationVector = new byte[12];
1043                     //noinspection ResultOfMethodCallIgnored
1044                     encryptedImportFileInputStream.read(initializationVector);
1045
1046                     // Convert the encryption password to a byte array.
1047                     byte[] encryptionPasswordByteArray = encryptionPasswordString.getBytes(StandardCharsets.UTF_8);
1048
1049                     // Append the salt to the encryption password byte array.  This protects against rainbow table attacks.
1050                     byte[] encryptionPasswordWithSaltByteArray = new byte[encryptionPasswordByteArray.length + saltByteArray.length];
1051                     System.arraycopy(encryptionPasswordByteArray, 0, encryptionPasswordWithSaltByteArray, 0, encryptionPasswordByteArray.length);
1052                     System.arraycopy(saltByteArray, 0, encryptionPasswordWithSaltByteArray, encryptionPasswordByteArray.length, saltByteArray.length);
1053
1054                     // Get a SHA-512 message digest.
1055                     MessageDigest messageDigest = MessageDigest.getInstance("SHA-512");
1056
1057                     // Hash the salted encryption password.  Otherwise, any characters after the 32nd character in the password are ignored.
1058                     byte[] hashedEncryptionPasswordWithSaltByteArray = messageDigest.digest(encryptionPasswordWithSaltByteArray);
1059
1060                     // Truncate the encryption password byte array to 256 bits (32 bytes).
1061                     byte[] truncatedHashedEncryptionPasswordWithSaltByteArray = Arrays.copyOf(hashedEncryptionPasswordWithSaltByteArray, 32);
1062
1063                     // Create an AES secret key from the encryption password byte array.
1064                     SecretKeySpec secretKey = new SecretKeySpec(truncatedHashedEncryptionPasswordWithSaltByteArray, "AES");
1065
1066                     // 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.
1067                     Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
1068
1069                     // Set the GCM tag length to be 128 bits (the maximum) and apply the initialization vector.
1070                     GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, initializationVector);
1071
1072                     // Initialize the cipher.
1073                     cipher.init(Cipher.DECRYPT_MODE, secretKey, gcmParameterSpec);
1074
1075                     // Create a cipher input stream.
1076                     CipherInputStream cipherInputStream = new CipherInputStream(encryptedImportFileInputStream, cipher);
1077
1078                     // 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.
1079                     int numberOfBytesRead;
1080                     byte[] decryptedBytes = new byte[16];
1081
1082                     // 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.
1083                     while ((numberOfBytesRead = cipherInputStream.read(decryptedBytes)) != -1) {
1084                         // Write the data to the unencrypted import file output stream.
1085                         unencryptedImportFileOutputStream.write(decryptedBytes, 0, numberOfBytesRead);
1086                     }
1087
1088                     // Close the streams.
1089                     unencryptedImportFileOutputStream.flush();
1090                     unencryptedImportFileOutputStream.close();
1091                     cipherInputStream.close();
1092                     encryptedImportFileInputStream.close();
1093
1094                     // Wipe the encryption data from memory.
1095                     //noinspection UnusedAssignment
1096                     encryptionPasswordString = "";
1097                     Arrays.fill(saltByteArray, (byte) 0);
1098                     Arrays.fill(initializationVector, (byte) 0);
1099                     Arrays.fill(encryptionPasswordByteArray, (byte) 0);
1100                     Arrays.fill(encryptionPasswordWithSaltByteArray, (byte) 0);
1101                     Arrays.fill(hashedEncryptionPasswordWithSaltByteArray, (byte) 0);
1102                     Arrays.fill(truncatedHashedEncryptionPasswordWithSaltByteArray, (byte) 0);
1103                     Arrays.fill(decryptedBytes, (byte) 0);
1104
1105                     // Import the unencrypted database from the private location.
1106                     importStatus = importExportDatabaseHelper.importUnencrypted(temporaryUnencryptedImportFile, this);
1107
1108                     // Delete the temporary unencrypted import file.
1109                     //noinspection ResultOfMethodCallIgnored
1110                     temporaryUnencryptedImportFile.delete();
1111                 } catch (Exception exception) {
1112                     importStatus = exception.toString();
1113                 }
1114                 break;
1115
1116             case OPENPGP_ENCRYPTION:
1117                 try {
1118                     // Create an decryption intent for OpenKeychain.
1119                     Intent openKeychainDecryptIntent = new Intent("org.sufficientlysecure.keychain.action.DECRYPT_DATA");
1120
1121                     // Include the URI to be decrypted.
1122                     openKeychainDecryptIntent.setData(FileProvider.getUriForFile(this, getString(R.string.file_provider), importFile));
1123
1124                     // Allow OpenKeychain to read the file URI.
1125                     openKeychainDecryptIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
1126
1127                     // Send the intent to the OpenKeychain package.
1128                     openKeychainDecryptIntent.setPackage("org.sufficientlysecure.keychain");
1129
1130                     // Make it so.
1131                     startActivity(openKeychainDecryptIntent);
1132                 } catch (IllegalArgumentException exception) {  // The file import location is not valid.
1133                     // Display a snack bar with the import error.
1134                     Snackbar.make(fileNameEditText, getString(R.string.import_failed) + "  " + exception.toString(), Snackbar.LENGTH_INDEFINITE).show();
1135                 }
1136                 break;
1137         }
1138
1139         // Respond to the import disposition.
1140         if (importStatus.equals(ImportExportDatabaseHelper.IMPORT_SUCCESSFUL)) {  // The import was successful.
1141             // Create an intent to restart Privacy Browser.
1142             Intent restartIntent = getParentActivityIntent();
1143
1144             // Assert that the intent is not null to remove the lint error below.
1145             assert restartIntent != null;
1146
1147             // `Intent.FLAG_ACTIVITY_CLEAR_TASK` removes all activities from the stack.  It requires `Intent.FLAG_ACTIVITY_NEW_TASK`.
1148             restartIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
1149
1150             // Create a restart handler.
1151             Handler restartHandler = new Handler();
1152
1153             // Create a restart runnable.
1154             Runnable restartRunnable =  () -> {
1155                 // Restart Privacy Browser.
1156                 startActivity(restartIntent);
1157
1158                 // Kill this instance of Privacy Browser.  Otherwise, the app exhibits sporadic behavior after the restart.
1159                 System.exit(0);
1160             };
1161
1162             // Restart Privacy Browser after 150 milliseconds to allow enough time for the preferences to be saved.
1163             restartHandler.postDelayed(restartRunnable, 150);
1164
1165         } else if (!(encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION)){  // The import was not successful.
1166             // Display a snack bar with the import error.
1167             Snackbar.make(fileNameEditText, getString(R.string.import_failed) + "  " + importStatus, Snackbar.LENGTH_INDEFINITE).show();
1168         }
1169     }
1170 }