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.BuildConfig;
  62 import com.stoutner.privacybrowser.R;
  63 import com.stoutner.privacybrowser.dialogs.StoragePermissionDialog;
  64 import com.stoutner.privacybrowser.helpers.DownloadLocationHelper;
  65 import com.stoutner.privacybrowser.helpers.FileNameHelper;
  66 import com.stoutner.privacybrowser.helpers.ImportExportDatabaseHelper;
  67
  68 import java.io.File;
  69 import java.io.FileInputStream;
  70 import java.io.FileOutputStream;
  71 import java.nio.charset.StandardCharsets;
  72 import java.security.MessageDigest;
  73 import java.security.SecureRandom;
  74 import java.util.Arrays;
  75
  76 import javax.crypto.Cipher;
  77 import javax.crypto.CipherInputStream;
  78 import javax.crypto.CipherOutputStream;
  79 import javax.crypto.spec.GCMParameterSpec;
  80 import javax.crypto.spec.SecretKeySpec;
  81
  82 public class ImportExportActivity extends AppCompatActivity implements StoragePermissionDialog.StoragePermissionDialogListener {
  83     // Define the encryption constants.
  84     private final int NO_ENCRYPTION = 0;
  85     private final int PASSWORD_ENCRYPTION = 1;
  86     private final int OPENPGP_ENCRYPTION = 2;
  87
  88     // Define the activity result constants.
  89     private final int BROWSE_RESULT_CODE = 0;
  90     private final int OPENPGP_EXPORT_RESULT_CODE = 1;
  91
  92     // Define the saved instance state constants.
  93     private final String PASSWORD_ENCRYPTED_TEXTINPUTLAYOUT_VISIBILITY = "password_encrypted_textinputlayout_visibility";
  94     private final String KITKAT_PASSWORD_ENCRYPTED_TEXTVIEW_VISIBILITY = "kitkat_password_encrypted_textview_visibility";
  95     private final String OPEN_KEYCHAIN_REQUIRED_TEXTVIEW_VISIBILITY = "open_keychain_required_textview_visibility";
  96     private final String FILE_LOCATION_CARD_VIEW = "file_location_card_view";
  97     private final String FILE_NAME_LINEARLAYOUT_VISIBILITY = "file_name_linearlayout_visibility";
  98     private final String FILE_DOES_NOT_EXIST_TEXTVIEW_VISIBILITY = "file_does_not_exist_textview_visibility";
  99     private final String FILE_EXISTS_WARNING_TEXTVIEW_VISIBILITY = "file_exists_warning_textview_visibility";
 100     private final String OPEN_KEYCHAIN_IMPORT_INSTRUCTIONS_TEXTVIEW_VISIBILITY = "open_keychain_import_instructions_textview_visibility";
 101     private final String IMPORT_EXPORT_BUTTON_VISIBILITY = "import_export_button_visibility";
 102     private final String FILE_NAME_TEXT = "file_name_text";
 103     private final String IMPORT_EXPORT_BUTTON_TEXT = "import_export_button_text";
 104
 105     // Define the class views.
 106     TextInputLayout passwordEncryptionTextInputLayout;
 107     TextView kitKatPasswordEncryptionTextView;
 108     TextView openKeychainRequiredTextView;
 109     CardView fileLocationCardView;
 110     LinearLayout fileNameLinearLayout;
 111     EditText fileNameEditText;
 112     TextView fileDoesNotExistTextView;
 113     TextView fileExistsWarningTextView;
 114     TextView openKeychainImportInstructionsTextView;
 115     Button importExportButton;
 116
 117     // Define the class variables.
 118     private boolean openKeychainInstalled;
 119
 120     @Override
 121     public void onCreate(Bundle savedInstanceState) {
 122         // Get a handle for the shared preferences.
 123         SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
 124
 125         // Get the screenshot preference.
 126         boolean allowScreenshots = sharedPreferences.getBoolean("allow_screenshots", false);
 127
 128         // Disable screenshots if not allowed.
 129         if (!allowScreenshots) {
 130             getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);
 131         }
 132
 133         // Set the theme.
 134         setTheme(R.style.PrivacyBrowser);
 135
 136         // Run the default commands.
 137         super.onCreate(savedInstanceState);
 138
 139         // Set the content view.
 140         setContentView(R.layout.import_export_coordinatorlayout);
 141
 142         // Set the support action bar.
 143         Toolbar toolbar = findViewById(R.id.import_export_toolbar);
 144         setSupportActionBar(toolbar);
 145
 146         // Get a handle for the action bar.
 147         ActionBar actionBar = getSupportActionBar();
 148
 149         // Remove the incorrect lint warning that the action bar might be null.
 150         assert actionBar != null;
 151
 152         // Display the home arrow on the support action bar.
 153         actionBar.setDisplayHomeAsUpEnabled(true);
 154
 155         // Find out if the system is running KitKat
 156         boolean runningKitKat = (Build.VERSION.SDK_INT == 19);
 157
 158         // Find out if OpenKeychain is installed.
 159         try {
 160             openKeychainInstalled = !getPackageManager().getPackageInfo("org.sufficientlysecure.keychain", 0).versionName.isEmpty();
 161         } catch (PackageManager.NameNotFoundException exception) {
 162             openKeychainInstalled = false;
 163         }
 164
 165         // Get handles for the views that need to be modified.
 166         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 167         passwordEncryptionTextInputLayout = findViewById(R.id.password_encryption_textinputlayout);
 168         EditText encryptionPasswordEditText = findViewById(R.id.password_encryption_edittext);
 169         kitKatPasswordEncryptionTextView = findViewById(R.id.kitkat_password_encryption_textview);
 170         openKeychainRequiredTextView = findViewById(R.id.openkeychain_required_textview);
 171         fileLocationCardView = findViewById(R.id.file_location_cardview);
 172         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 173         RadioButton exportRadioButton = findViewById(R.id.export_radiobutton);
 174         fileNameLinearLayout = findViewById(R.id.file_name_linearlayout);
 175         fileNameEditText = findViewById(R.id.file_name_edittext);
 176         fileDoesNotExistTextView = findViewById(R.id.file_does_not_exist_textview);
 177         fileExistsWarningTextView = findViewById(R.id.file_exists_warning_textview);
 178         openKeychainImportInstructionsTextView = findViewById(R.id.openkeychain_import_instructions_textview);
 179         importExportButton = findViewById(R.id.import_export_button);
 180         TextView storagePermissionTextView = findViewById(R.id.import_export_storage_permission_textview);
 181
 182         // Create an array adapter for the spinner.
 183         ArrayAdapter<CharSequence> encryptionArrayAdapter = ArrayAdapter.createFromResource(this, R.array.encryption_type, R.layout.spinner_item);
 184
 185         // Set the drop down view resource on the spinner.
 186         encryptionArrayAdapter.setDropDownViewResource(R.layout.spinner_dropdown_items);
 187
 188         // Set the array adapter for the spinner.
 189         encryptionSpinner.setAdapter(encryptionArrayAdapter);
 190
 191         // Instantiate the download location helper.
 192         DownloadLocationHelper downloadLocationHelper = new DownloadLocationHelper();
 193
 194         // Get the default file path.
 195         String defaultFilePath = downloadLocationHelper.getDownloadLocation(this) + "/" + getString(R.string.settings) + " " + BuildConfig.VERSION_NAME + ".pbs";
 196
 197         // Set the other default file paths.
 198         String defaultPasswordEncryptionFilePath = defaultFilePath + ".aes";
 199         String defaultPgpFilePath = defaultFilePath + ".pgp";
 200
 201         // Set the default file path.
 202         fileNameEditText.setText(defaultFilePath);
 203
 204         // Hide the storage permission text view if the permission has already been granted.
 205         if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
 206             storagePermissionTextView.setVisibility(View.GONE);
 207         }
 208
 209         // Update the UI when the spinner changes.
 210         encryptionSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
 211             @Override
 212             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
 213                 switch (position) {
 214                     case NO_ENCRYPTION:
 215                         // Hide the unneeded layout items.
 216                         passwordEncryptionTextInputLayout.setVisibility(View.GONE);
 217                         kitKatPasswordEncryptionTextView.setVisibility(View.GONE);
 218                         openKeychainRequiredTextView.setVisibility(View.GONE);
 219                         openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 220
 221                         // Show the file location card.
 222                         fileLocationCardView.setVisibility(View.VISIBLE);
 223
 224                         // Show the file name linear layout if either import or export is checked.
 225                         if (importRadioButton.isChecked() || exportRadioButton.isChecked()) {
 226                             fileNameLinearLayout.setVisibility(View.VISIBLE);
 227                         }
 228
 229                         // Reset the text of the import button, which may have been changed to `Decrypt`.
 230                         if (importRadioButton.isChecked()) {
 231                             importExportButton.setText(R.string.import_button);
 232                         }
 233
 234                         // Reset the default file path.
 235                         fileNameEditText.setText(defaultFilePath);
 236                         break;
 237
 238                     case PASSWORD_ENCRYPTION:
 239                         if (runningKitKat) {
 240                             // Show the KitKat password encryption message.
 241                             kitKatPasswordEncryptionTextView.setVisibility(View.VISIBLE);
 242
 243                             // Hide the OpenPGP required text view and the file location card.
 244                             openKeychainRequiredTextView.setVisibility(View.GONE);
 245                             fileLocationCardView.setVisibility(View.GONE);
 246                         } else {
 247                             // Hide the OpenPGP layout items.
 248                             openKeychainRequiredTextView.setVisibility(View.GONE);
 249                             openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 250
 251                             // Show the password encryption layout items.
 252                             passwordEncryptionTextInputLayout.setVisibility(View.VISIBLE);
 253
 254                             // Show the file location card.
 255                             fileLocationCardView.setVisibility(View.VISIBLE);
 256
 257                             // Show the file name linear layout if either import or export is checked.
 258                             if (importRadioButton.isChecked() || exportRadioButton.isChecked()) {
 259                                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 260                             }
 261
 262                             // Reset the text of the import button, which may have been changed to `Decrypt`.
 263                             if (importRadioButton.isChecked()) {
 264                                 importExportButton.setText(R.string.import_button);
 265                             }
 266
 267                             // Update the default file path.
 268                             fileNameEditText.setText(defaultPasswordEncryptionFilePath);
 269                         }
 270                         break;
 271
 272                     case OPENPGP_ENCRYPTION:
 273                         // Hide the password encryption layout items.
 274                         passwordEncryptionTextInputLayout.setVisibility(View.GONE);
 275                         kitKatPasswordEncryptionTextView.setVisibility(View.GONE);
 276
 277                         // Updated items based on the installation status of OpenKeychain.
 278                         if (openKeychainInstalled) {  // OpenKeychain is installed.
 279                             // Update the default file path.
 280                             fileNameEditText.setText(defaultPgpFilePath);
 281
 282                             // Show the file location card.
 283                             fileLocationCardView.setVisibility(View.VISIBLE);
 284
 285                             if (importRadioButton.isChecked()) {
 286                                 // Show the file name linear layout and the OpenKeychain import instructions.
 287                                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 288                                 openKeychainImportInstructionsTextView.setVisibility(View.VISIBLE);
 289
 290                                 // Set the text of the import button to be `Decrypt`.
 291                                 importExportButton.setText(R.string.decrypt);
 292                             } else if (exportRadioButton.isChecked()) {
 293                                 // Hide the file name linear layout and the OpenKeychain import instructions.
 294                                 fileNameLinearLayout.setVisibility(View.GONE);
 295                                 openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 296                             }
 297                         } else {  // OpenKeychain is not installed.
 298                             // Show the OpenPGP required layout item.
 299                             openKeychainRequiredTextView.setVisibility(View.VISIBLE);
 300
 301                             // Hide the file location card.
 302                             fileLocationCardView.setVisibility(View.GONE);
 303                         }
 304                         break;
 305                 }
 306             }
 307
 308             @Override
 309             public void onNothingSelected(AdapterView<?> parent) {
 310
 311             }
 312         });
 313
 314         // Update the status of the import/export button when the password changes.
 315         encryptionPasswordEditText.addTextChangedListener(new TextWatcher() {
 316             @Override
 317             public void beforeTextChanged(CharSequence s, int start, int count, int after) {
 318                 // Do nothing.
 319             }
 320
 321             @Override
 322             public void onTextChanged(CharSequence s, int start, int before, int count) {
 323                 // Do nothing.
 324             }
 325
 326             @Override
 327             public void afterTextChanged(Editable s) {
 328                 // Get the current file name.
 329                 String fileNameString = fileNameEditText.getText().toString();
 330
 331                 // Convert the file name string to a file.
 332                 File file = new File(fileNameString);
 333
 334                 // Update the import/export button.
 335                 if (importRadioButton.isChecked()) {  // The import radio button is checked.
 336                     // Enable the import button if the file and the password exists.
 337                     importExportButton.setEnabled(file.exists() && !encryptionPasswordEditText.getText().toString().isEmpty());
 338                 } else if (exportRadioButton.isChecked()) {  // The export radio button is checked.
 339                     // Enable the export button if the file string and the password exists.
 340                     importExportButton.setEnabled(!fileNameString.isEmpty() && !encryptionPasswordEditText.getText().toString().isEmpty());
 341                 }
 342             }
 343         });
 344
 345         // Update the UI when the file name EditText changes.
 346         fileNameEditText.addTextChangedListener(new TextWatcher() {
 347             @Override
 348             public void beforeTextChanged(CharSequence s, int start, int count, int after) {
 349                 // Do nothing.
 350             }
 351
 352             @Override
 353             public void onTextChanged(CharSequence s, int start, int before, int count) {
 354                 // Do nothing.
 355             }
 356
 357             @Override
 358             public void afterTextChanged(Editable s) {
 359                 // Get the current file name.
 360                 String fileNameString = fileNameEditText.getText().toString();
 361
 362                 // Convert the file name string to a file.
 363                 File file = new File(fileNameString);
 364
 365                 // Adjust the UI according to the encryption spinner position.
 366                 switch (encryptionSpinner.getSelectedItemPosition()) {
 367                     case NO_ENCRYPTION:
 368                         // Determine if import or export is checked.
 369                         if (exportRadioButton.isChecked()) {  // The export radio button is checked.
 370                             // Hide the file does not exist text view.
 371                             fileDoesNotExistTextView.setVisibility(View.GONE);
 372
 373                             // Display a warning if the file already exists.
 374                             if (file.exists()) {
 375                                 fileExistsWarningTextView.setVisibility(View.VISIBLE);
 376                             } else {
 377                                 fileExistsWarningTextView.setVisibility(View.GONE);
 378                             }
 379
 380                             // Enable the export button if the file name is populated.
 381                             importExportButton.setEnabled(!fileNameString.isEmpty());
 382                         } else if (importRadioButton.isChecked()) {  // The import radio button is checked.
 383                             // Hide the file exists warning text view.
 384                             fileExistsWarningTextView.setVisibility(View.GONE);
 385
 386                             // Check if the file exists.
 387                             if (file.exists()) {  // The file exists.
 388                                 // Hide the notification that the file does not exist.
 389                                 fileDoesNotExistTextView.setVisibility(View.GONE);
 390
 391                                 // Enable the import button.
 392                                 importExportButton.setEnabled(true);
 393                             } else {  // The file does not exist.
 394                                 // Show a notification that the file does not exist.
 395                                 fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 396
 397                                 // Disable the import button.
 398                                 importExportButton.setEnabled(false);
 399                             }
 400                         } else {  // Neither radio button is checked.
 401                             // Hide the file notification text views.
 402                             fileExistsWarningTextView.setVisibility(View.GONE);
 403                             fileDoesNotExistTextView.setVisibility(View.GONE);
 404                         }
 405                         break;
 406
 407                     case PASSWORD_ENCRYPTION:
 408                         // Determine if import or export is checked.
 409                         if (exportRadioButton.isChecked()) {  // The export radio button is checked.
 410                             // Hide the notification that the file does not exist.
 411                             fileDoesNotExistTextView.setVisibility(View.GONE);
 412
 413                             // Display a warning if the file already exists.
 414                             if (file.exists()) {
 415                                 fileExistsWarningTextView.setVisibility(View.VISIBLE);
 416                             } else {
 417                                 fileExistsWarningTextView.setVisibility(View.GONE);
 418                             }
 419
 420                             // Enable the export button if the file name and the password are populated.
 421                             importExportButton.setEnabled(!fileNameString.isEmpty() && !encryptionPasswordEditText.getText().toString().isEmpty());
 422                         } else if (importRadioButton.isChecked()) {  // The import radio button is checked.
 423                             // Hide the file exists warning text view.
 424                             fileExistsWarningTextView.setVisibility(View.GONE);
 425
 426                             // Check if the file exists.
 427                             if (file.exists()) {  // The file exists.
 428                                 // Hide the notification that the file does not exist.
 429                                 fileDoesNotExistTextView.setVisibility(View.GONE);
 430
 431                                 // Enable the import button if the password is populated.
 432                                 importExportButton.setEnabled(!encryptionPasswordEditText.getText().toString().isEmpty());
 433                             } else {  // The file does not exist.
 434                                 // Show a notification that the file does not exist.
 435                                 fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 436
 437                                 // Disable the import button.
 438                                 importExportButton.setEnabled(false);
 439                             }
 440                         } else {  // Neither radio button is checked.
 441                             // Hide the file notification text views.
 442                             fileExistsWarningTextView.setVisibility(View.GONE);
 443                             fileDoesNotExistTextView.setVisibility(View.GONE);
 444                         }
 445                         break;
 446
 447                     case OPENPGP_ENCRYPTION:
 448                         // Hide the file exists warning text view.
 449                         fileExistsWarningTextView.setVisibility(View.GONE);
 450
 451                         if (importRadioButton.isChecked()) {  // The import radio button is checked.
 452                             if (file.exists()) {  // The file exists.
 453                                 // Hide the notification that the file does not exist.
 454                                 fileDoesNotExistTextView.setVisibility(View.GONE);
 455
 456                                 // Enable the import button if OpenKeychain is installed.
 457                                 importExportButton.setEnabled(openKeychainInstalled);
 458                             } else {  // The file does not exist.
 459                                 // Show the notification that the file does not exist.
 460                                 fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 461
 462                                 // Disable the import button.
 463                                 importExportButton.setEnabled(false);
 464                             }
 465                         } else if (exportRadioButton.isChecked()){  // The export radio button is checked.
 466                             // Hide the notification that the file does not exist.
 467                             fileDoesNotExistTextView.setVisibility(View.GONE);
 468
 469                             // Enable the export button.
 470                             importExportButton.setEnabled(true);
 471                         } else {  // Neither radio button is checked.
 472                             // Hide the notification that the file does not exist.
 473                             fileDoesNotExistTextView.setVisibility(View.GONE);
 474                         }
 475                         break;
 476                 }
 477             }
 478         });
 479
 480         // Check to see if the activity has been restarted.
 481         if (savedInstanceState == null) {  // The app has not been restarted.
 482             // Initially hide the unneeded views.
 483             passwordEncryptionTextInputLayout.setVisibility(View.GONE);
 484             kitKatPasswordEncryptionTextView.setVisibility(View.GONE);
 485             openKeychainRequiredTextView.setVisibility(View.GONE);
 486             fileNameLinearLayout.setVisibility(View.GONE);
 487             fileDoesNotExistTextView.setVisibility(View.GONE);
 488             fileExistsWarningTextView.setVisibility(View.GONE);
 489             openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 490             importExportButton.setVisibility(View.GONE);
 491         } else {  // The app has been restarted.
 492             // Restore the visibility of the views.
 493             passwordEncryptionTextInputLayout.setVisibility(savedInstanceState.getInt(PASSWORD_ENCRYPTED_TEXTINPUTLAYOUT_VISIBILITY));
 494             kitKatPasswordEncryptionTextView.setVisibility(savedInstanceState.getInt(KITKAT_PASSWORD_ENCRYPTED_TEXTVIEW_VISIBILITY));
 495             openKeychainRequiredTextView.setVisibility(savedInstanceState.getInt(OPEN_KEYCHAIN_REQUIRED_TEXTVIEW_VISIBILITY));
 496             fileLocationCardView.setVisibility(savedInstanceState.getInt(FILE_LOCATION_CARD_VIEW));
 497             fileNameLinearLayout.setVisibility(savedInstanceState.getInt(FILE_NAME_LINEARLAYOUT_VISIBILITY));
 498             fileDoesNotExistTextView.setVisibility(savedInstanceState.getInt(FILE_DOES_NOT_EXIST_TEXTVIEW_VISIBILITY));
 499             fileExistsWarningTextView.setVisibility(savedInstanceState.getInt(FILE_EXISTS_WARNING_TEXTVIEW_VISIBILITY));
 500             openKeychainImportInstructionsTextView.setVisibility(savedInstanceState.getInt(OPEN_KEYCHAIN_IMPORT_INSTRUCTIONS_TEXTVIEW_VISIBILITY));
 501             importExportButton.setVisibility(savedInstanceState.getInt(IMPORT_EXPORT_BUTTON_VISIBILITY));
 502
 503             // Restore the text.
 504             fileNameEditText.post(() -> fileNameEditText.setText(savedInstanceState.getString(FILE_NAME_TEXT)));
 505             importExportButton.setText(savedInstanceState.getString(IMPORT_EXPORT_BUTTON_TEXT));
 506         }
 507     }
 508
 509     @Override
 510     public void onSaveInstanceState (@NonNull Bundle savedInstanceState) {
 511         // Run the default commands.
 512         super.onSaveInstanceState(savedInstanceState);
 513
 514         // Save the visibility of the views.
 515         savedInstanceState.putInt(PASSWORD_ENCRYPTED_TEXTINPUTLAYOUT_VISIBILITY, passwordEncryptionTextInputLayout.getVisibility());
 516         savedInstanceState.putInt(KITKAT_PASSWORD_ENCRYPTED_TEXTVIEW_VISIBILITY, kitKatPasswordEncryptionTextView.getVisibility());
 517         savedInstanceState.putInt(OPEN_KEYCHAIN_REQUIRED_TEXTVIEW_VISIBILITY, openKeychainRequiredTextView.getVisibility());
 518         savedInstanceState.putInt(FILE_LOCATION_CARD_VIEW, fileLocationCardView.getVisibility());
 519         savedInstanceState.putInt(FILE_NAME_LINEARLAYOUT_VISIBILITY, fileNameLinearLayout.getVisibility());
 520         savedInstanceState.putInt(FILE_DOES_NOT_EXIST_TEXTVIEW_VISIBILITY, fileDoesNotExistTextView.getVisibility());
 521         savedInstanceState.putInt(FILE_EXISTS_WARNING_TEXTVIEW_VISIBILITY, fileExistsWarningTextView.getVisibility());
 522         savedInstanceState.putInt(OPEN_KEYCHAIN_IMPORT_INSTRUCTIONS_TEXTVIEW_VISIBILITY, openKeychainImportInstructionsTextView.getVisibility());
 523         savedInstanceState.putInt(IMPORT_EXPORT_BUTTON_VISIBILITY, importExportButton.getVisibility());
 524
 525         // Save the text.
 526         savedInstanceState.putString(FILE_NAME_TEXT, fileNameEditText.getText().toString());
 527         savedInstanceState.putString(IMPORT_EXPORT_BUTTON_TEXT, importExportButton.getText().toString());
 528     }
 529
 530     public void onClickRadioButton(View view) {
 531         // Get handles for the views.
 532         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 533         LinearLayout fileNameLinearLayout = findViewById(R.id.file_name_linearlayout);
 534         EditText passwordEncryptionEditText = findViewById(R.id.password_encryption_edittext);
 535         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 536         TextView fileDoesNotExistTextView = findViewById(R.id.file_does_not_exist_textview);
 537         TextView fileExistsWarningTextView = findViewById(R.id.file_exists_warning_textview);
 538         TextView openKeychainImportInstructionTextView = findViewById(R.id.openkeychain_import_instructions_textview);
 539         Button importExportButton = findViewById(R.id.import_export_button);
 540
 541         // Get the current file name.
 542         String fileNameString = fileNameEditText.getText().toString();
 543
 544         // Convert the file name string to a file.
 545         File file = new File(fileNameString);
 546
 547         // Check to see if import or export was selected.
 548         switch (view.getId()) {
 549             case R.id.import_radiobutton:
 550                 // Check to see if OpenPGP encryption is selected.
 551                 if (encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) {  // OpenPGP encryption selected.
 552                     // Show the OpenKeychain import instructions.
 553                     openKeychainImportInstructionTextView.setVisibility(View.VISIBLE);
 554
 555                     // Set the text on the import/export button to be `Decrypt`.
 556                     importExportButton.setText(R.string.decrypt);
 557                 } else {  // OpenPGP encryption not selected.
 558                     // Hide the OpenKeychain import instructions.
 559                     openKeychainImportInstructionTextView.setVisibility(View.GONE);
 560
 561                     // Set the text on the import/export button to be `Import`.
 562                     importExportButton.setText(R.string.import_button);
 563                 }
 564
 565                 // Hide the file exists warning text view.
 566                 fileExistsWarningTextView.setVisibility(View.GONE);
 567
 568                 // Display the file name views.
 569                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 570                 importExportButton.setVisibility(View.VISIBLE);
 571
 572                 // Check to see if the file exists.
 573                 if (file.exists()) {  // The file exists.
 574                     // Hide the notification that the file does not exist.
 575                     fileDoesNotExistTextView.setVisibility(View.GONE);
 576
 577                     // Check to see if password encryption is selected.
 578                     if (encryptionSpinner.getSelectedItemPosition() == PASSWORD_ENCRYPTION) {  // Password encryption is selected.
 579                         // Enable the import button if the encryption password is populated.
 580                         importExportButton.setEnabled(!passwordEncryptionEditText.getText().toString().isEmpty());
 581                     } else {  // Password encryption is not selected.
 582                         // Enable the import/decrypt button.
 583                         importExportButton.setEnabled(true);
 584                     }
 585                 } else {  // The file does not exist.
 586                     // Show the notification that the file does not exist.
 587                     fileDoesNotExistTextView.setVisibility(View.VISIBLE);
 588
 589                     // Disable the import/decrypt button.
 590                     importExportButton.setEnabled(false);
 591                 }
 592                 break;
 593
 594             case R.id.export_radiobutton:
 595                 // Hide the OpenKeychain import instructions.
 596                 openKeychainImportInstructionTextView.setVisibility(View.GONE);
 597
 598                 // Set the text on the import/export button to be `Export`.
 599                 importExportButton.setText(R.string.export);
 600
 601                 // Show the import/export button.
 602                 importExportButton.setVisibility(View.VISIBLE);
 603
 604                 // Check to see if OpenPGP encryption is selected.
 605                 if (encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) {  // OpenPGP encryption is selected.
 606                     // Hide the file name views.
 607                     fileNameLinearLayout.setVisibility(View.GONE);
 608                     fileDoesNotExistTextView.setVisibility(View.GONE);
 609                     fileExistsWarningTextView.setVisibility(View.GONE);
 610
 611                     // Enable the export button.
 612                     importExportButton.setEnabled(true);
 613                 } else {  // OpenPGP encryption is not selected.
 614                     // Show the file name view.
 615                     fileNameLinearLayout.setVisibility(View.VISIBLE);
 616
 617                     // Hide the notification that the file name does not exist.
 618                     fileDoesNotExistTextView.setVisibility(View.GONE);
 619
 620                     // Display a warning if the file already exists.
 621                     if (file.exists()) {
 622                         fileExistsWarningTextView.setVisibility(View.VISIBLE);
 623                     } else {
 624                         fileExistsWarningTextView.setVisibility(View.GONE);
 625                     }
 626
 627                     // Check the encryption type.
 628                     if (encryptionSpinner.getSelectedItemPosition() == NO_ENCRYPTION) {  // No encryption is selected.
 629                         // Enable the export button if the file name is populated.
 630                         importExportButton.setEnabled(!fileNameString.isEmpty());
 631                     } else {  // Password encryption is selected.
 632                         // Enable the export button if the file name and the password are populated.
 633                         importExportButton.setEnabled(!fileNameString.isEmpty() && !passwordEncryptionEditText.getText().toString().isEmpty());
 634                     }
 635                 }
 636                 break;
 637         }
 638     }
 639
 640     public void browse(View view) {
 641         // Get a handle for the views.
 642         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 643         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 644
 645         // Check to see if import or export is selected.
 646         if (importRadioButton.isChecked()) {  // Import is selected.
 647             // Create the file picker intent.
 648             Intent importBrowseIntent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
 649
 650             // Set the intent MIME type to include all files so that everything is visible.
 651             importBrowseIntent.setType("*/*");
 652
 653             // Set the initial directory if the minimum API >= 26.
 654             if (Build.VERSION.SDK_INT >= 26) {
 655                 importBrowseIntent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, Environment.getExternalStorageDirectory());
 656             }
 657
 658             // Request a file that can be opened.
 659             importBrowseIntent.addCategory(Intent.CATEGORY_OPENABLE);
 660
 661             // Launch the file picker.
 662             startActivityForResult(importBrowseIntent, BROWSE_RESULT_CODE);
 663         } else {  // Export is selected
 664             // Create the file picker intent.
 665             Intent exportBrowseIntent = new Intent(Intent.ACTION_CREATE_DOCUMENT);
 666
 667             // Set the intent MIME type to include all files so that everything is visible.
 668             exportBrowseIntent.setType("*/*");
 669
 670             // Set the initial export file name according to the encryption type.
 671             if (encryptionSpinner.getSelectedItemPosition() == NO_ENCRYPTION) {  // No encryption is selected.
 672                 exportBrowseIntent.putExtra(Intent.EXTRA_TITLE, getString(R.string.settings) + " " + BuildConfig.VERSION_NAME + ".pbs");
 673             } else {  // Password encryption is selected.
 674                 exportBrowseIntent.putExtra(Intent.EXTRA_TITLE, getString(R.string.settings) + " " + BuildConfig.VERSION_NAME + ".pbs.aes");
 675             }
 676
 677             // Set the initial directory if the minimum API >= 26.
 678             if (Build.VERSION.SDK_INT >= 26) {
 679                 exportBrowseIntent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, Environment.getExternalStorageDirectory());
 680             }
 681
 682             // Request a file that can be opened.
 683             exportBrowseIntent.addCategory(Intent.CATEGORY_OPENABLE);
 684
 685             // Launch the file picker.
 686             startActivityForResult(exportBrowseIntent, BROWSE_RESULT_CODE);
 687         }
 688     }
 689
 690     public void importExport(View view) {
 691         // Get a handle for the views.
 692         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 693         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 694         RadioButton exportRadioButton = findViewById(R.id.export_radiobutton);
 695
 696         // Check to see if the storage permission is needed.
 697         if ((encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) && exportRadioButton.isChecked()) {  // Permission not needed to export via OpenKeychain.
 698             // Export the settings.
 699             exportSettings();
 700         } else if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {  // The storage permission has been granted.
 701             // Check to see if import or export is selected.
 702             if (importRadioButton.isChecked()) {  // Import is selected.
 703                 // Import the settings.
 704                 importSettings();
 705             } else {  // Export is selected.
 706                 // Export the settings.
 707                 exportSettings();
 708             }
 709         } else {  // The storage permission has not been granted.
 710             // Get a handle for the file name EditText.
 711             EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 712
 713             // Get the file name string.
 714             String fileNameString = fileNameEditText.getText().toString();
 715
 716             // Get the external private directory `File`.
 717             File externalPrivateDirectoryFile = getExternalFilesDir(null);
 718
 719             // Remove the incorrect lint error below that the file might be null.
 720             assert externalPrivateDirectoryFile != null;
 721
 722             // Get the external private directory string.
 723             String externalPrivateDirectory = externalPrivateDirectoryFile.toString();
 724
 725             // Check to see if the file path is in the external private directory.
 726             if (fileNameString.startsWith(externalPrivateDirectory)) {  // The file path is in the external private directory.
 727                 // Check to see if import or export is selected.
 728                 if (importRadioButton.isChecked()) {  // Import is selected.
 729                     // Import the settings.
 730                     importSettings();
 731                 } else {  // Export is selected.
 732                     // Export the settings.
 733                     exportSettings();
 734                 }
 735             } else {  // The file path is in a public directory.
 736                 // Check if the user has previously denied the storage permission.
 737                 if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {  // Show a dialog explaining the request first.
 738                     // Instantiate the storage permission alert dialog.
 739                     DialogFragment storagePermissionDialogFragment = StoragePermissionDialog.displayDialog(0);
 740
 741                     // Show the storage permission alert dialog.  The permission will be requested when the dialog is closed.
 742                     storagePermissionDialogFragment.show(getSupportFragmentManager(), getString(R.string.storage_permission));
 743                 } else {  // Show the permission request directly.
 744                     // Request the storage permission.  The export will be run when it finishes.
 745                     ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);
 746                 }
 747             }
 748         }
 749     }
 750
 751     @Override
 752     public void onCloseStoragePermissionDialog(int type) {
 753         // Request the write external storage permission.  The import/export will be run when it finishes.
 754         ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);
 755     }
 756
 757     @Override
 758     public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
 759         // Get a handle for the import radiobutton.
 760         RadioButton importRadioButton = findViewById(R.id.import_radiobutton);
 761
 762         // Check to see if the storage permission was granted.  If the dialog was canceled the grant results will be empty.
 763         if ((grantResults.length > 0) && (grantResults[0] == PackageManager.PERMISSION_GRANTED)) {  // The storage permission was granted.
 764             // Run the import or export methods according to which radio button is selected.
 765             if (importRadioButton.isChecked()) {  // Import is selected.
 766                 // Import the settings.
 767                 importSettings();
 768             } else {  // Export is selected.
 769                 // Export the settings.
 770                 exportSettings();
 771             }
 772         } else {  // The storage permission was not granted.
 773             // Display an error snackbar.
 774             Snackbar.make(importRadioButton, getString(R.string.cannot_use_location), Snackbar.LENGTH_LONG).show();
 775         }
 776     }
 777
 778     @Override
 779     public void onActivityResult(int requestCode, int resultCode, Intent intent) {
 780         // Run the default commands.
 781         super.onActivityResult(requestCode, resultCode, intent);
 782
 783         switch (requestCode) {
 784             case (BROWSE_RESULT_CODE):
 785                 // Don't do anything if the user pressed back from the file picker.
 786                 if (resultCode == Activity.RESULT_OK) {
 787                     // Get a handle for the views.
 788                     EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 789                     TextView fileExistsWarningTextView = findViewById(R.id.file_exists_warning_textview);
 790
 791                     // Instantiate the file name helper.
 792                     FileNameHelper fileNameHelper = new FileNameHelper();
 793
 794                     // Get the file path URI from the intent.
 795                     Uri filePathUri = intent.getData();
 796
 797                     // Use the file path from the intent if it exists.
 798                     if (filePathUri != null) {
 799                         // Convert the file name URI to a file name path.
 800                         String fileNamePath = fileNameHelper.convertUriToFileNamePath(filePathUri);
 801
 802                         // Set the file name path as the text of the file name edit text.
 803                         fileNameEditText.setText(fileNamePath);
 804
 805                         // Hide the file exists warning text view, because the file picker will have just created a file if export was selected.
 806                         fileExistsWarningTextView.setVisibility(View.GONE);
 807                     }
 808                 }
 809                 break;
 810
 811             case OPENPGP_EXPORT_RESULT_CODE:
 812                 // Get the temporary unencrypted export file.
 813                 File temporaryUnencryptedExportFile = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.settings) + " " + BuildConfig.VERSION_NAME + ".pbs");
 814
 815                 // Delete the temporary unencrypted export file if it exists.
 816                 if (temporaryUnencryptedExportFile.exists()) {
 817                     //noinspection ResultOfMethodCallIgnored
 818                     temporaryUnencryptedExportFile.delete();
 819                 }
 820                 break;
 821         }
 822     }
 823
 824     private void exportSettings() {
 825         // Get a handle for the views.
 826         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 827         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 828
 829         // Instantiate the import export database helper.
 830         ImportExportDatabaseHelper importExportDatabaseHelper = new ImportExportDatabaseHelper();
 831
 832         // Get the export file string.
 833         String exportFileString = fileNameEditText.getText().toString();
 834
 835         // Get the export and temporary unencrypted export files.
 836         File exportFile = new File(exportFileString);
 837         File temporaryUnencryptedExportFile = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.settings) + " " + BuildConfig.VERSION_NAME + ".pbs");
 838
 839         // Create an export status string.
 840         String exportStatus;
 841
 842         // Export according to the encryption type.
 843         switch (encryptionSpinner.getSelectedItemPosition()) {
 844             case NO_ENCRYPTION:
 845                 // Export the unencrypted file.
 846                 exportStatus = importExportDatabaseHelper.exportUnencrypted(exportFile, this);
 847
 848                 // Show a disposition snackbar.
 849                 if (exportStatus.equals(ImportExportDatabaseHelper.EXPORT_SUCCESSFUL)) {
 850                     Snackbar.make(fileNameEditText, getString(R.string.export_successful), Snackbar.LENGTH_SHORT).show();
 851                 } else {
 852                     Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + exportStatus, Snackbar.LENGTH_INDEFINITE).show();
 853                 }
 854                 break;
 855
 856             case PASSWORD_ENCRYPTION:
 857                 // Create an unencrypted export in a private directory.
 858                 exportStatus = importExportDatabaseHelper.exportUnencrypted(temporaryUnencryptedExportFile, this);
 859
 860                 try {
 861                     // Create an unencrypted export file input stream.
 862                     FileInputStream unencryptedExportFileInputStream = new FileInputStream(temporaryUnencryptedExportFile);
 863
 864                     // Delete the encrypted export file if it exists.
 865                     if (exportFile.exists()) {
 866                         //noinspection ResultOfMethodCallIgnored
 867                         exportFile.delete();
 868                     }
 869
 870                     // Create an encrypted export file output stream.
 871                     FileOutputStream encryptedExportFileOutputStream = new FileOutputStream(exportFile);
 872
 873                     // Get a handle for the encryption password EditText.
 874                     EditText encryptionPasswordEditText = findViewById(R.id.password_encryption_edittext);
 875
 876                     // Get the encryption password.
 877                     String encryptionPasswordString = encryptionPasswordEditText.getText().toString();
 878
 879                     // Initialize a secure random number generator.
 880                     SecureRandom secureRandom = new SecureRandom();
 881
 882                     // Get a 256 bit (32 byte) random salt.
 883                     byte[] saltByteArray = new byte[32];
 884                     secureRandom.nextBytes(saltByteArray);
 885
 886                     // Convert the encryption password to a byte array.
 887                     byte[] encryptionPasswordByteArray = encryptionPasswordString.getBytes(StandardCharsets.UTF_8);
 888
 889                     // Append the salt to the encryption password byte array.  This protects against rainbow table attacks.
 890                     byte[] encryptionPasswordWithSaltByteArray = new byte[encryptionPasswordByteArray.length + saltByteArray.length];
 891                     System.arraycopy(encryptionPasswordByteArray, 0, encryptionPasswordWithSaltByteArray, 0, encryptionPasswordByteArray.length);
 892                     System.arraycopy(saltByteArray, 0, encryptionPasswordWithSaltByteArray, encryptionPasswordByteArray.length, saltByteArray.length);
 893
 894                     // Get a SHA-512 message digest.
 895                     MessageDigest messageDigest = MessageDigest.getInstance("SHA-512");
 896
 897                     // Hash the salted encryption password.  Otherwise, any characters after the 32nd character in the password are ignored.
 898                     byte[] hashedEncryptionPasswordWithSaltByteArray = messageDigest.digest(encryptionPasswordWithSaltByteArray);
 899
 900                     // Truncate the encryption password byte array to 256 bits (32 bytes).
 901                     byte[] truncatedHashedEncryptionPasswordWithSaltByteArray = Arrays.copyOf(hashedEncryptionPasswordWithSaltByteArray, 32);
 902
 903                     // Create an AES secret key from the encryption password byte array.
 904                     SecretKeySpec secretKey = new SecretKeySpec(truncatedHashedEncryptionPasswordWithSaltByteArray, "AES");
 905
 906                     // Generate a random 12 byte initialization vector.  According to NIST, a 12 byte initialization vector is more secure than a 16 byte one.
 907                     byte[] initializationVector = new byte[12];
 908                     secureRandom.nextBytes(initializationVector);
 909
 910                     // 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.
 911                     Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
 912
 913                     // Set the GCM tag length to be 128 bits (the maximum) and apply the initialization vector.
 914                     GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, initializationVector);
 915
 916                     // Initialize the cipher.
 917                     cipher.init(Cipher.ENCRYPT_MODE, secretKey, gcmParameterSpec);
 918
 919                     // Add the salt and the initialization vector to the export file.
 920                     encryptedExportFileOutputStream.write(saltByteArray);
 921                     encryptedExportFileOutputStream.write(initializationVector);
 922
 923                     // Create a cipher output stream.
 924                     CipherOutputStream cipherOutputStream = new CipherOutputStream(encryptedExportFileOutputStream, cipher);
 925
 926                     // 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.
 927                     int numberOfBytesRead;
 928                     byte[] encryptedBytes = new byte[16];
 929
 930                     // 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.
 931                     while ((numberOfBytesRead = unencryptedExportFileInputStream.read(encryptedBytes)) != -1) {
 932                         // Write the data to the cipher output stream.
 933                         cipherOutputStream.write(encryptedBytes, 0, numberOfBytesRead);
 934                     }
 935
 936                     // Close the streams.
 937                     cipherOutputStream.flush();
 938                     cipherOutputStream.close();
 939                     encryptedExportFileOutputStream.close();
 940                     unencryptedExportFileInputStream.close();
 941
 942                     // Wipe the encryption data from memory.
 943                     //noinspection UnusedAssignment
 944                     encryptionPasswordString = "";
 945                     Arrays.fill(saltByteArray, (byte) 0);
 946                     Arrays.fill(encryptionPasswordByteArray, (byte) 0);
 947                     Arrays.fill(encryptionPasswordWithSaltByteArray, (byte) 0);
 948                     Arrays.fill(hashedEncryptionPasswordWithSaltByteArray, (byte) 0);
 949                     Arrays.fill(truncatedHashedEncryptionPasswordWithSaltByteArray, (byte) 0);
 950                     Arrays.fill(initializationVector, (byte) 0);
 951                     Arrays.fill(encryptedBytes, (byte) 0);
 952
 953                     // Delete the temporary unencrypted export file.
 954                     //noinspection ResultOfMethodCallIgnored
 955                     temporaryUnencryptedExportFile.delete();
 956                 } catch (Exception exception) {
 957                     exportStatus = exception.toString();
 958                 }
 959
 960                 // Show a disposition snackbar.
 961                 if (exportStatus.equals(ImportExportDatabaseHelper.EXPORT_SUCCESSFUL)) {
 962                     Snackbar.make(fileNameEditText, getString(R.string.export_successful), Snackbar.LENGTH_SHORT).show();
 963                 } else {
 964                     Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + exportStatus, Snackbar.LENGTH_INDEFINITE).show();
 965                 }
 966                 break;
 967
 968             case OPENPGP_ENCRYPTION:
 969                 // Create an unencrypted export in the private location.
 970                 importExportDatabaseHelper.exportUnencrypted(temporaryUnencryptedExportFile, this);
 971
 972                 // Create an encryption intent for OpenKeychain.
 973                 Intent openKeychainEncryptIntent = new Intent("org.sufficientlysecure.keychain.action.ENCRYPT_DATA");
 974
 975                 // Include the temporary unencrypted export file URI.
 976                 openKeychainEncryptIntent.setData(FileProvider.getUriForFile(this, getString(R.string.file_provider), temporaryUnencryptedExportFile));
 977
 978                 // Allow OpenKeychain to read the file URI.
 979                 openKeychainEncryptIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
 980
 981                 // Send the intent to the OpenKeychain package.
 982                 openKeychainEncryptIntent.setPackage("org.sufficientlysecure.keychain");
 983
 984                 // Make it so.
 985                 startActivityForResult(openKeychainEncryptIntent, OPENPGP_EXPORT_RESULT_CODE);
 986                 break;
 987         }
 988
 989         // Add the file to the list of recent files.  This doesn't currently work, but maybe it will someday.
 990         MediaScannerConnection.scanFile(this, new String[] {exportFileString}, new String[] {"application/x-sqlite3"}, null);
 991     }
 992
 993     private void importSettings() {
 994         // Get a handle for the views.
 995         Spinner encryptionSpinner = findViewById(R.id.encryption_spinner);
 996         EditText fileNameEditText = findViewById(R.id.file_name_edittext);
 997
 998         // Instantiate the import export database helper.
 999         ImportExportDatabaseHelper importExportDatabaseHelper = new ImportExportDatabaseHelper();
1000
1001         // Get the import file.
1002         File importFile = new File(fileNameEditText.getText().toString());
1003
1004         // Initialize the import status string
1005         String importStatus = "";
1006
1007         // Import according to the encryption type.
1008         switch (encryptionSpinner.getSelectedItemPosition()) {
1009             case NO_ENCRYPTION:
1010                 // Import the unencrypted file.
1011                 importStatus = importExportDatabaseHelper.importUnencrypted(importFile, this);
1012                 break;
1013
1014             case PASSWORD_ENCRYPTION:
1015                 // Use a private temporary import location.
1016                 File temporaryUnencryptedImportFile = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.settings) + " " + BuildConfig.VERSION_NAME + ".pbs");
1017
1018                 try {
1019                     // Create an encrypted import file input stream.
1020                     FileInputStream encryptedImportFileInputStream = new FileInputStream(importFile);
1021
1022                     // Delete the temporary import file if it exists.
1023                     if (temporaryUnencryptedImportFile.exists()) {
1024                         //noinspection ResultOfMethodCallIgnored
1025                         temporaryUnencryptedImportFile.delete();
1026                     }
1027
1028                     // Create an unencrypted import file output stream.
1029                     FileOutputStream unencryptedImportFileOutputStream = new FileOutputStream(temporaryUnencryptedImportFile);
1030
1031                     // Get a handle for the encryption password EditText.
1032                     EditText encryptionPasswordEditText = findViewById(R.id.password_encryption_edittext);
1033
1034                     // Get the encryption password.
1035                     String encryptionPasswordString = encryptionPasswordEditText.getText().toString();
1036
1037                     // Get the salt from the beginning of the import file.
1038                     byte[] saltByteArray = new byte[32];
1039                     //noinspection ResultOfMethodCallIgnored
1040                     encryptedImportFileInputStream.read(saltByteArray);
1041
1042                     // Get the initialization vector from the import file.
1043                     byte[] initializationVector = new byte[12];
1044                     //noinspection ResultOfMethodCallIgnored
1045                     encryptedImportFileInputStream.read(initializationVector);
1046
1047                     // Convert the encryption password to a byte array.
1048                     byte[] encryptionPasswordByteArray = encryptionPasswordString.getBytes(StandardCharsets.UTF_8);
1049
1050                     // Append the salt to the encryption password byte array.  This protects against rainbow table attacks.
1051                     byte[] encryptionPasswordWithSaltByteArray = new byte[encryptionPasswordByteArray.length + saltByteArray.length];
1052                     System.arraycopy(encryptionPasswordByteArray, 0, encryptionPasswordWithSaltByteArray, 0, encryptionPasswordByteArray.length);
1053                     System.arraycopy(saltByteArray, 0, encryptionPasswordWithSaltByteArray, encryptionPasswordByteArray.length, saltByteArray.length);
1054
1055                     // Get a SHA-512 message digest.
1056                     MessageDigest messageDigest = MessageDigest.getInstance("SHA-512");
1057
1058                     // Hash the salted encryption password.  Otherwise, any characters after the 32nd character in the password are ignored.
1059                     byte[] hashedEncryptionPasswordWithSaltByteArray = messageDigest.digest(encryptionPasswordWithSaltByteArray);
1060
1061                     // Truncate the encryption password byte array to 256 bits (32 bytes).
1062                     byte[] truncatedHashedEncryptionPasswordWithSaltByteArray = Arrays.copyOf(hashedEncryptionPasswordWithSaltByteArray, 32);
1063
1064                     // Create an AES secret key from the encryption password byte array.
1065                     SecretKeySpec secretKey = new SecretKeySpec(truncatedHashedEncryptionPasswordWithSaltByteArray, "AES");
1066
1067                     // 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.
1068                     Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
1069
1070                     // Set the GCM tag length to be 128 bits (the maximum) and apply the initialization vector.
1071                     GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, initializationVector);
1072
1073                     // Initialize the cipher.
1074                     cipher.init(Cipher.DECRYPT_MODE, secretKey, gcmParameterSpec);
1075
1076                     // Create a cipher input stream.
1077                     CipherInputStream cipherInputStream = new CipherInputStream(encryptedImportFileInputStream, cipher);
1078
1079                     // 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.
1080                     int numberOfBytesRead;
1081                     byte[] decryptedBytes = new byte[16];
1082
1083                     // 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.
1084                     while ((numberOfBytesRead = cipherInputStream.read(decryptedBytes)) != -1) {
1085                         // Write the data to the unencrypted import file output stream.
1086                         unencryptedImportFileOutputStream.write(decryptedBytes, 0, numberOfBytesRead);
1087                     }
1088
1089                     // Close the streams.
1090                     unencryptedImportFileOutputStream.flush();
1091                     unencryptedImportFileOutputStream.close();
1092                     cipherInputStream.close();
1093                     encryptedImportFileInputStream.close();
1094
1095                     // Wipe the encryption data from memory.
1096                     //noinspection UnusedAssignment
1097                     encryptionPasswordString = "";
1098                     Arrays.fill(saltByteArray, (byte) 0);
1099                     Arrays.fill(initializationVector, (byte) 0);
1100                     Arrays.fill(encryptionPasswordByteArray, (byte) 0);
1101                     Arrays.fill(encryptionPasswordWithSaltByteArray, (byte) 0);
1102                     Arrays.fill(hashedEncryptionPasswordWithSaltByteArray, (byte) 0);
1103                     Arrays.fill(truncatedHashedEncryptionPasswordWithSaltByteArray, (byte) 0);
1104                     Arrays.fill(decryptedBytes, (byte) 0);
1105
1106                     // Import the unencrypted database from the private location.
1107                     importStatus = importExportDatabaseHelper.importUnencrypted(temporaryUnencryptedImportFile, this);
1108
1109                     // Delete the temporary unencrypted import file.
1110                     //noinspection ResultOfMethodCallIgnored
1111                     temporaryUnencryptedImportFile.delete();
1112                 } catch (Exception exception) {
1113                     importStatus = exception.toString();
1114                 }
1115                 break;
1116
1117             case OPENPGP_ENCRYPTION:
1118                 try {
1119                     // Create an decryption intent for OpenKeychain.
1120                     Intent openKeychainDecryptIntent = new Intent("org.sufficientlysecure.keychain.action.DECRYPT_DATA");
1121
1122                     // Include the URI to be decrypted.
1123                     openKeychainDecryptIntent.setData(FileProvider.getUriForFile(this, getString(R.string.file_provider), importFile));
1124
1125                     // Allow OpenKeychain to read the file URI.
1126                     openKeychainDecryptIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
1127
1128                     // Send the intent to the OpenKeychain package.
1129                     openKeychainDecryptIntent.setPackage("org.sufficientlysecure.keychain");
1130
1131                     // Make it so.
1132                     startActivity(openKeychainDecryptIntent);
1133                 } catch (IllegalArgumentException exception) {  // The file import location is not valid.
1134                     // Display a snack bar with the import error.
1135                     Snackbar.make(fileNameEditText, getString(R.string.import_failed) + "  " + exception.toString(), Snackbar.LENGTH_INDEFINITE).show();
1136                 }
1137                 break;
1138         }
1139
1140         // Respond to the import disposition.
1141         if (importStatus.equals(ImportExportDatabaseHelper.IMPORT_SUCCESSFUL)) {  // The import was successful.
1142             // Create an intent to restart Privacy Browser.
1143             Intent restartIntent = getParentActivityIntent();
1144
1145             // Assert that the intent is not null to remove the lint error below.
1146             assert restartIntent != null;
1147
1148             // `Intent.FLAG_ACTIVITY_CLEAR_TASK` removes all activities from the stack.  It requires `Intent.FLAG_ACTIVITY_NEW_TASK`.
1149             restartIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
1150
1151             // Create a restart handler.
1152             Handler restartHandler = new Handler();
1153
1154             // Create a restart runnable.
1155             Runnable restartRunnable =  () -> {
1156                 // Restart Privacy Browser.
1157                 startActivity(restartIntent);
1158
1159                 // Kill this instance of Privacy Browser.  Otherwise, the app exhibits sporadic behavior after the restart.
1160                 System.exit(0);
1161             };
1162
1163             // Restart Privacy Browser after 150 milliseconds to allow enough time for the preferences to be saved.
1164             restartHandler.postDelayed(restartRunnable, 150);
1165
1166         } else if (!(encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION)){  // The import was not successful.
1167             // Display a snack bar with the import error.
1168             Snackbar.make(fileNameEditText, getString(R.string.import_failed) + "  " + importStatus, Snackbar.LENGTH_INDEFINITE).show();
1169         }
1170     }
1171 }