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

   1 /*
   2  * Copyright 2018-2022 Soren Stoutner <soren@stoutner.com>.
   3  *
   4  * This file is part of Privacy Browser Android <https://www.stoutner.com/privacy-browser-android>.
   5  *
   6  * Privacy Browser Android 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 Android 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 Android.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 package com.stoutner.privacybrowser.activities;
  21
  22 import android.app.Activity;
  23 import android.content.Intent;
  24 import android.content.SharedPreferences;
  25 import android.content.pm.PackageManager;
  26 import android.net.Uri;
  27 import android.os.Bundle;
  28 import android.os.Handler;
  29 import android.text.Editable;
  30 import android.text.TextWatcher;
  31 import android.view.View;
  32 import android.view.WindowManager;
  33 import android.widget.AdapterView;
  34 import android.widget.ArrayAdapter;
  35 import android.widget.Button;
  36 import android.widget.EditText;
  37 import android.widget.LinearLayout;
  38 import android.widget.RadioButton;
  39 import android.widget.Spinner;
  40 import android.widget.TextView;
  41
  42 import androidx.annotation.NonNull;
  43 import androidx.appcompat.app.ActionBar;
  44 import androidx.appcompat.app.AppCompatActivity;
  45 import androidx.appcompat.widget.Toolbar;
  46 import androidx.cardview.widget.CardView;
  47 import androidx.core.content.FileProvider;
  48 import androidx.preference.PreferenceManager;
  49
  50 import com.google.android.material.snackbar.Snackbar;
  51 import com.google.android.material.textfield.TextInputLayout;
  52
  53 import com.stoutner.privacybrowser.BuildConfig;
  54 import com.stoutner.privacybrowser.R;
  55 import com.stoutner.privacybrowser.helpers.ImportExportDatabaseHelper;
  56
  57 import java.io.File;
  58 import java.io.FileInputStream;
  59 import java.io.FileNotFoundException;
  60 import java.io.FileOutputStream;
  61 import java.io.InputStream;
  62 import java.io.OutputStream;
  63 import java.nio.charset.StandardCharsets;
  64 import java.security.MessageDigest;
  65 import java.security.SecureRandom;
  66 import java.util.Arrays;
  67
  68 import javax.crypto.Cipher;
  69 import javax.crypto.CipherInputStream;
  70 import javax.crypto.CipherOutputStream;
  71 import javax.crypto.spec.GCMParameterSpec;
  72 import javax.crypto.spec.SecretKeySpec;
  73
  74 public class ImportExportActivity extends AppCompatActivity {
  75     // Define the encryption constants.
  76     private final int NO_ENCRYPTION = 0;
  77     private final int PASSWORD_ENCRYPTION = 1;
  78     private final int OPENPGP_ENCRYPTION = 2;
  79
  80     // Define the activity result constants.
  81     private final int BROWSE_RESULT_CODE = 0;
  82     private final int OPENPGP_IMPORT_RESULT_CODE = 1;
  83     private final int OPENPGP_EXPORT_RESULT_CODE = 2;
  84
  85     // Define the saved instance state constants.
  86     private final String ENCRYPTION_PASSWORD_TEXTINPUTLAYOUT_VISIBILITY = "encryption_password_textinputlayout_visibility";
  87     private final String OPEN_KEYCHAIN_REQUIRED_TEXTVIEW_VISIBILITY = "open_keychain_required_textview_visibility";
  88     private final String FILE_LOCATION_CARD_VIEW = "file_location_card_view";
  89     private final String FILE_NAME_LINEARLAYOUT_VISIBILITY = "file_name_linearlayout_visibility";
  90     private final String OPEN_KEYCHAIN_IMPORT_INSTRUCTIONS_TEXTVIEW_VISIBILITY = "open_keychain_import_instructions_textview_visibility";
  91     private final String IMPORT_EXPORT_BUTTON_VISIBILITY = "import_export_button_visibility";
  92     private final String FILE_NAME_TEXT = "file_name_text";
  93     private final String IMPORT_EXPORT_BUTTON_TEXT = "import_export_button_text";
  94
  95     // Define the class views.
  96     Spinner encryptionSpinner;
  97     TextInputLayout encryptionPasswordTextInputLayout;
  98     EditText encryptionPasswordEditText;
  99     TextView openKeychainRequiredTextView;
 100     CardView fileLocationCardView;
 101     RadioButton importRadioButton;
 102     LinearLayout fileNameLinearLayout;
 103     EditText fileNameEditText;
 104     TextView openKeychainImportInstructionsTextView;
 105     Button importExportButton;
 106
 107     // Define the class variables.
 108     private File fileProviderDirectory;
 109     private boolean openKeychainInstalled;
 110     private File temporaryPgpEncryptedImportFile;
 111     private File temporaryPreEncryptedExportFile;
 112
 113     @Override
 114     public void onCreate(Bundle savedInstanceState) {
 115         // Get a handle for the shared preferences.
 116         SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
 117
 118         // Get the preferences.
 119         boolean allowScreenshots = sharedPreferences.getBoolean(getString(R.string.allow_screenshots_key), false);
 120         boolean bottomAppBar = sharedPreferences.getBoolean(getString(R.string.bottom_app_bar_key), false);
 121
 122         // Disable screenshots if not allowed.
 123         if (!allowScreenshots) {
 124             getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);
 125         }
 126
 127         // Run the default commands.
 128         super.onCreate(savedInstanceState);
 129
 130         // Set the content view.
 131         if (bottomAppBar) {
 132             setContentView(R.layout.import_export_bottom_appbar);
 133         } else {
 134             setContentView(R.layout.import_export_top_appbar);
 135         }
 136
 137         // Get a handle for the toolbar.
 138         Toolbar toolbar = findViewById(R.id.import_export_toolbar);
 139
 140         // Set the support action bar.
 141         setSupportActionBar(toolbar);
 142
 143         // Get a handle for the action bar.
 144         ActionBar actionBar = getSupportActionBar();
 145
 146         // Remove the incorrect lint warning that the action bar might be null.
 147         assert actionBar != null;
 148
 149         // Display the home arrow on the support action bar.
 150         actionBar.setDisplayHomeAsUpEnabled(true);
 151
 152         // Find out if OpenKeychain is installed.
 153         try {
 154             openKeychainInstalled = !getPackageManager().getPackageInfo("org.sufficientlysecure.keychain", 0).versionName.isEmpty();
 155         } catch (PackageManager.NameNotFoundException exception) {
 156             openKeychainInstalled = false;
 157         }
 158
 159         // Get handles for the views that need to be modified.
 160         encryptionSpinner = findViewById(R.id.encryption_spinner);
 161         encryptionPasswordTextInputLayout = findViewById(R.id.encryption_password_textinputlayout);
 162         encryptionPasswordEditText = findViewById(R.id.encryption_password_edittext);
 163         openKeychainRequiredTextView = findViewById(R.id.openkeychain_required_textview);
 164         fileLocationCardView = findViewById(R.id.file_location_cardview);
 165         importRadioButton = findViewById(R.id.import_radiobutton);
 166         RadioButton exportRadioButton = findViewById(R.id.export_radiobutton);
 167         fileNameLinearLayout = findViewById(R.id.file_name_linearlayout);
 168         fileNameEditText = findViewById(R.id.file_name_edittext);
 169         openKeychainImportInstructionsTextView = findViewById(R.id.openkeychain_import_instructions_textview);
 170         importExportButton = findViewById(R.id.import_export_button);
 171
 172         // Create an array adapter for the spinner.
 173         ArrayAdapter<CharSequence> encryptionArrayAdapter = ArrayAdapter.createFromResource(this, R.array.encryption_type, R.layout.spinner_item);
 174
 175         // Set the drop down view resource on the spinner.
 176         encryptionArrayAdapter.setDropDownViewResource(R.layout.spinner_dropdown_items);
 177
 178         // Set the array adapter for the spinner.
 179         encryptionSpinner.setAdapter(encryptionArrayAdapter);
 180
 181         // Update the UI when the spinner changes.
 182         encryptionSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
 183             @Override
 184             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
 185                 switch (position) {
 186                     case NO_ENCRYPTION:
 187                         // Hide the unneeded layout items.
 188                         encryptionPasswordTextInputLayout.setVisibility(View.GONE);
 189                         openKeychainRequiredTextView.setVisibility(View.GONE);
 190                         openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 191
 192                         // Show the file location card.
 193                         fileLocationCardView.setVisibility(View.VISIBLE);
 194
 195                         // Show the file name linear layout if either import or export is checked.
 196                         if (importRadioButton.isChecked() || exportRadioButton.isChecked()) {
 197                             fileNameLinearLayout.setVisibility(View.VISIBLE);
 198                         }
 199
 200                         // Reset the text of the import button, which may have been changed to `Decrypt`.
 201                         if (importRadioButton.isChecked()) {
 202                             importExportButton.setText(R.string.import_button);
 203                         }
 204
 205                         // Enable the import/export button if the file name is populated.
 206                         importExportButton.setEnabled(!fileNameEditText.getText().toString().isEmpty());
 207                         break;
 208
 209                     case PASSWORD_ENCRYPTION:
 210                         // Hide the OpenPGP layout items.
 211                         openKeychainRequiredTextView.setVisibility(View.GONE);
 212                         openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 213
 214                         // Show the password encryption layout items.
 215                         encryptionPasswordTextInputLayout.setVisibility(View.VISIBLE);
 216
 217                         // Show the file location card.
 218                         fileLocationCardView.setVisibility(View.VISIBLE);
 219
 220                         // Show the file name linear layout if either import or export is checked.
 221                         if (importRadioButton.isChecked() || exportRadioButton.isChecked()) {
 222                             fileNameLinearLayout.setVisibility(View.VISIBLE);
 223                         }
 224
 225                         // Reset the text of the import button, which may have been changed to `Decrypt`.
 226                         if (importRadioButton.isChecked()) {
 227                             importExportButton.setText(R.string.import_button);
 228                         }
 229
 230                         // Enable the import/button if both the password and the file name are populated.
 231                         importExportButton.setEnabled(!fileNameEditText.getText().toString().isEmpty() && !encryptionPasswordEditText.getText().toString().isEmpty());
 232                         break;
 233
 234                     case OPENPGP_ENCRYPTION:
 235                         // Hide the password encryption layout items.
 236                         encryptionPasswordTextInputLayout.setVisibility(View.GONE);
 237
 238                         // Updated items based on the installation status of OpenKeychain.
 239                         if (openKeychainInstalled) {  // OpenKeychain is installed.
 240                             // Show the file location card.
 241                             fileLocationCardView.setVisibility(View.VISIBLE);
 242
 243                             if (importRadioButton.isChecked()) {
 244                                 // Show the file name linear layout and the OpenKeychain import instructions.
 245                                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 246                                 openKeychainImportInstructionsTextView.setVisibility(View.VISIBLE);
 247
 248                                 // Set the text of the import button to be `Decrypt`.
 249                                 importExportButton.setText(R.string.decrypt);
 250
 251                                 // Enable the import button if the file name is populated.
 252                                 importExportButton.setEnabled(!fileNameEditText.getText().toString().isEmpty());
 253                             } else if (exportRadioButton.isChecked()) {
 254                                 // Hide the file name linear layout and the OpenKeychain import instructions.
 255                                 fileNameLinearLayout.setVisibility(View.GONE);
 256                                 openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 257
 258                                 // Enable the export button.
 259                                 importExportButton.setEnabled(true);
 260                             }
 261                         } else {  // OpenKeychain is not installed.
 262                             // Show the OpenPGP required layout item.
 263                             openKeychainRequiredTextView.setVisibility(View.VISIBLE);
 264
 265                             // Hide the file location card.
 266                             fileLocationCardView.setVisibility(View.GONE);
 267                         }
 268                         break;
 269                 }
 270             }
 271
 272             @Override
 273             public void onNothingSelected(AdapterView<?> parent) {
 274
 275             }
 276         });
 277
 278         // Update the status of the import/export button when the password changes.
 279         encryptionPasswordEditText.addTextChangedListener(new TextWatcher() {
 280             @Override
 281             public void beforeTextChanged(CharSequence s, int start, int count, int after) {
 282                 // Do nothing.
 283             }
 284
 285             @Override
 286             public void onTextChanged(CharSequence s, int start, int before, int count) {
 287                 // Do nothing.
 288             }
 289
 290             @Override
 291             public void afterTextChanged(Editable s) {
 292                 // Enable the import/export button if both the file string and the password are populated.
 293                 importExportButton.setEnabled(!fileNameEditText.getText().toString().isEmpty() && !encryptionPasswordEditText.getText().toString().isEmpty());
 294             }
 295         });
 296
 297         // Update the UI when the file name EditText changes.
 298         fileNameEditText.addTextChangedListener(new TextWatcher() {
 299             @Override
 300             public void beforeTextChanged(CharSequence s, int start, int count, int after) {
 301                 // Do nothing.
 302             }
 303
 304             @Override
 305             public void onTextChanged(CharSequence s, int start, int before, int count) {
 306                 // Do nothing.
 307             }
 308
 309             @Override
 310             public void afterTextChanged(Editable s) {
 311                 // Adjust the UI according to the encryption spinner position.
 312                 if (encryptionSpinner.getSelectedItemPosition() == PASSWORD_ENCRYPTION) {
 313                     // Enable the import/export button if both the file name and the password are populated.
 314                     importExportButton.setEnabled(!fileNameEditText.getText().toString().isEmpty() && !encryptionPasswordEditText.getText().toString().isEmpty());
 315                 } else {
 316                     // Enable the export button if the file name is populated.
 317                     importExportButton.setEnabled(!fileNameEditText.getText().toString().isEmpty());
 318                 }
 319             }
 320         });
 321
 322         // Check to see if the activity has been restarted.
 323         if (savedInstanceState == null) {  // The app has not been restarted.
 324             // Initially hide the unneeded views.
 325             encryptionPasswordTextInputLayout.setVisibility(View.GONE);
 326             openKeychainRequiredTextView.setVisibility(View.GONE);
 327             fileNameLinearLayout.setVisibility(View.GONE);
 328             openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 329             importExportButton.setVisibility(View.GONE);
 330         } else {  // The app has been restarted.
 331             // Restore the visibility of the views.
 332             encryptionPasswordTextInputLayout.setVisibility(savedInstanceState.getInt(ENCRYPTION_PASSWORD_TEXTINPUTLAYOUT_VISIBILITY));
 333             openKeychainRequiredTextView.setVisibility(savedInstanceState.getInt(OPEN_KEYCHAIN_REQUIRED_TEXTVIEW_VISIBILITY));
 334             fileLocationCardView.setVisibility(savedInstanceState.getInt(FILE_LOCATION_CARD_VIEW));
 335             fileNameLinearLayout.setVisibility(savedInstanceState.getInt(FILE_NAME_LINEARLAYOUT_VISIBILITY));
 336             openKeychainImportInstructionsTextView.setVisibility(savedInstanceState.getInt(OPEN_KEYCHAIN_IMPORT_INSTRUCTIONS_TEXTVIEW_VISIBILITY));
 337             importExportButton.setVisibility(savedInstanceState.getInt(IMPORT_EXPORT_BUTTON_VISIBILITY));
 338
 339             // Restore the text.
 340             fileNameEditText.post(() -> fileNameEditText.setText(savedInstanceState.getString(FILE_NAME_TEXT)));
 341             importExportButton.setText(savedInstanceState.getString(IMPORT_EXPORT_BUTTON_TEXT));
 342         }
 343     }
 344
 345     @Override
 346     public void onSaveInstanceState (@NonNull Bundle savedInstanceState) {
 347         // Run the default commands.
 348         super.onSaveInstanceState(savedInstanceState);
 349
 350         // Save the visibility of the views.
 351         savedInstanceState.putInt(ENCRYPTION_PASSWORD_TEXTINPUTLAYOUT_VISIBILITY, encryptionPasswordTextInputLayout.getVisibility());
 352         savedInstanceState.putInt(OPEN_KEYCHAIN_REQUIRED_TEXTVIEW_VISIBILITY, openKeychainRequiredTextView.getVisibility());
 353         savedInstanceState.putInt(FILE_LOCATION_CARD_VIEW, fileLocationCardView.getVisibility());
 354         savedInstanceState.putInt(FILE_NAME_LINEARLAYOUT_VISIBILITY, fileNameLinearLayout.getVisibility());
 355         savedInstanceState.putInt(OPEN_KEYCHAIN_IMPORT_INSTRUCTIONS_TEXTVIEW_VISIBILITY, openKeychainImportInstructionsTextView.getVisibility());
 356         savedInstanceState.putInt(IMPORT_EXPORT_BUTTON_VISIBILITY, importExportButton.getVisibility());
 357
 358         // Save the text.
 359         savedInstanceState.putString(FILE_NAME_TEXT, fileNameEditText.getText().toString());
 360         savedInstanceState.putString(IMPORT_EXPORT_BUTTON_TEXT, importExportButton.getText().toString());
 361     }
 362
 363     public void onClickRadioButton(View view) {
 364         // Get the current file name.
 365         String fileNameString = fileNameEditText.getText().toString();
 366
 367         // Convert the file name string to a file.
 368         File file = new File(fileNameString);
 369
 370         // Check to see if import or export was selected.
 371         if (view.getId() == R.id.import_radiobutton) {  // The import radio button is selected.
 372             // Check to see if OpenPGP encryption is selected.
 373             if (encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) {  // OpenPGP encryption selected.
 374                 // Show the OpenKeychain import instructions.
 375                 openKeychainImportInstructionsTextView.setVisibility(View.VISIBLE);
 376
 377                 // Set the text on the import/export button to be `Decrypt`.
 378                 importExportButton.setText(R.string.decrypt);
 379             } else {  // OpenPGP encryption not selected.
 380                 // Hide the OpenKeychain import instructions.
 381                 openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 382
 383                 // Set the text on the import/export button to be `Import`.
 384                 importExportButton.setText(R.string.import_button);
 385             }
 386
 387             // Display the file name views.
 388             fileNameLinearLayout.setVisibility(View.VISIBLE);
 389             importExportButton.setVisibility(View.VISIBLE);
 390
 391             // Check to see if the file exists.
 392             if (file.exists()) {  // The file exists.
 393                 // Check to see if password encryption is selected.
 394                 if (encryptionSpinner.getSelectedItemPosition() == PASSWORD_ENCRYPTION) {  // Password encryption is selected.
 395                     // Enable the import button if the encryption password is populated.
 396                     importExportButton.setEnabled(!encryptionPasswordEditText.getText().toString().isEmpty());
 397                 } else {  // Password encryption is not selected.
 398                     // Enable the import/decrypt button.
 399                     importExportButton.setEnabled(true);
 400                 }
 401             } else {  // The file does not exist.
 402                 // Disable the import/decrypt button.
 403                 importExportButton.setEnabled(false);
 404             }
 405         } else {  // The export radio button is selected.
 406             // Hide the OpenKeychain import instructions.
 407             openKeychainImportInstructionsTextView.setVisibility(View.GONE);
 408
 409             // Set the text on the import/export button to be `Export`.
 410             importExportButton.setText(R.string.export);
 411
 412             // Show the import/export button.
 413             importExportButton.setVisibility(View.VISIBLE);
 414
 415             // Check to see if OpenPGP encryption is selected.
 416             if (encryptionSpinner.getSelectedItemPosition() == OPENPGP_ENCRYPTION) {  // OpenPGP encryption is selected.
 417                 // Hide the file name views.
 418                 fileNameLinearLayout.setVisibility(View.GONE);
 419
 420                 // Enable the export button.
 421                 importExportButton.setEnabled(true);
 422             } else {  // OpenPGP encryption is not selected.
 423                 // Show the file name view.
 424                 fileNameLinearLayout.setVisibility(View.VISIBLE);
 425
 426                 // Check the encryption type.
 427                 if (encryptionSpinner.getSelectedItemPosition() == NO_ENCRYPTION) {  // No encryption is selected.
 428                     // Enable the export button if the file name is populated.
 429                     importExportButton.setEnabled(!fileNameString.isEmpty());
 430                 } else {  // Password encryption is selected.
 431                     // Enable the export button if the file name and the password are populated.
 432                     importExportButton.setEnabled(!fileNameString.isEmpty() && !encryptionPasswordEditText.getText().toString().isEmpty());
 433                 }
 434             }
 435         }
 436     }
 437
 438     public void browse(View view) {
 439         // Check to see if import or export is selected.
 440         if (importRadioButton.isChecked()) {  // Import is selected.
 441             // Create the file picker intent.
 442             Intent importBrowseIntent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
 443
 444             // Set the intent MIME type to include all files so that everything is visible.
 445             importBrowseIntent.setType("*/*");
 446
 447             // Request a file that can be opened.
 448             importBrowseIntent.addCategory(Intent.CATEGORY_OPENABLE);
 449
 450             // Launch the file picker.
 451             startActivityForResult(importBrowseIntent, BROWSE_RESULT_CODE);
 452         } else {  // Export is selected
 453             // Create the file picker intent.
 454             Intent exportBrowseIntent = new Intent(Intent.ACTION_CREATE_DOCUMENT);
 455
 456             // Set the intent MIME type to include all files so that everything is visible.
 457             exportBrowseIntent.setType("*/*");
 458
 459             // Set the initial export file name according to the encryption type.
 460             if (encryptionSpinner.getSelectedItemPosition() == NO_ENCRYPTION) {  // No encryption is selected.
 461                 exportBrowseIntent.putExtra(Intent.EXTRA_TITLE, getString(R.string.settings) + " " + BuildConfig.VERSION_NAME + ".pbs");
 462             } else {  // Password encryption is selected.
 463                 exportBrowseIntent.putExtra(Intent.EXTRA_TITLE, getString(R.string.settings) + " " + BuildConfig.VERSION_NAME + ".pbs.aes");
 464             }
 465
 466             // Request a file that can be opened.
 467             exportBrowseIntent.addCategory(Intent.CATEGORY_OPENABLE);
 468
 469             // Launch the file picker.
 470             startActivityForResult(exportBrowseIntent, BROWSE_RESULT_CODE);
 471         }
 472     }
 473
 474     @Override
 475     public void onActivityResult(int requestCode, int resultCode, Intent returnedIntent) {
 476         // Run the default commands.
 477         super.onActivityResult(requestCode, resultCode, returnedIntent);
 478
 479         switch (requestCode) {
 480             case (BROWSE_RESULT_CODE):
 481                 // Only do something if the user didn't press back from the file picker.
 482                 if (resultCode == Activity.RESULT_OK) {
 483                     // Get the file path URI from the intent.
 484                     Uri fileNameUri = returnedIntent.getData();
 485
 486                     // Get the file name string from the URI.
 487                     String fileNameString = fileNameUri.toString();
 488
 489                     // Set the file name name text.
 490                     fileNameEditText.setText(fileNameString);
 491
 492                     // Move the cursor to the end of the file name edit text.
 493                     fileNameEditText.setSelection(fileNameString.length());
 494                 }
 495                 break;
 496
 497             case OPENPGP_IMPORT_RESULT_CODE:
 498                 // Delete the temporary PGP encrypted import file.
 499                 if (temporaryPgpEncryptedImportFile.exists()) {
 500                     //noinspection ResultOfMethodCallIgnored
 501                     temporaryPgpEncryptedImportFile.delete();
 502                 }
 503
 504                 // Delete the file provider directory if it exists.
 505                 if (fileProviderDirectory.exists()) {
 506                     //noinspection ResultOfMethodCallIgnored
 507                     fileProviderDirectory.delete();
 508                 }
 509
 510                 break;
 511
 512             case OPENPGP_EXPORT_RESULT_CODE:
 513                 // Delete the temporary pre-encrypted export file if it exists.
 514                 if (temporaryPreEncryptedExportFile.exists()) {
 515                     //noinspection ResultOfMethodCallIgnored
 516                     temporaryPreEncryptedExportFile.delete();
 517                 }
 518
 519                 // Delete the file provider directory if it exists.
 520                 if (fileProviderDirectory.exists()) {
 521                     //noinspection ResultOfMethodCallIgnored
 522                     fileProviderDirectory.delete();
 523                 }
 524
 525                 break;
 526         }
 527     }
 528
 529     public void importExport(View view) {
 530         // Instantiate the import export database helper.
 531         ImportExportDatabaseHelper importExportDatabaseHelper = new ImportExportDatabaseHelper();
 532
 533         // Check to see if import or export is selected.
 534         if (importRadioButton.isChecked()) {  // Import is selected.
 535             // Initialize the import status string
 536             String importStatus = "";
 537
 538             // Get the file name string.
 539             String fileNameString = fileNameEditText.getText().toString();
 540
 541             // Import according to the encryption type.
 542             switch (encryptionSpinner.getSelectedItemPosition()) {
 543                 case NO_ENCRYPTION:
 544                     try {
 545                         // Get an input stream for the file name.
 546                         // A file may be opened directly once the minimum API >= 29.  <https://developer.android.com/reference/kotlin/android/content/ContentResolver#openfile>
 547                         InputStream inputStream = getContentResolver().openInputStream(Uri.parse(fileNameString));
 548
 549                         // Import the unencrypted file.
 550                         importStatus = importExportDatabaseHelper.importUnencrypted(inputStream, this);
 551                     } catch (FileNotFoundException exception) {
 552                         // Update the import status.
 553                         importStatus = exception.toString();
 554                     }
 555
 556                     // Restart Privacy Browser if successful.
 557                     if (importStatus.equals(ImportExportDatabaseHelper.IMPORT_SUCCESSFUL)) {
 558                         restartPrivacyBrowser();
 559                     }
 560                     break;
 561
 562                 case PASSWORD_ENCRYPTION:
 563                     try {
 564                         // Get the encryption password.
 565                         String encryptionPasswordString = encryptionPasswordEditText.getText().toString();
 566
 567                         // Get an input stream for the file name.
 568                         InputStream inputStream = getContentResolver().openInputStream(Uri.parse(fileNameString));
 569
 570                         // Get the salt from the beginning of the import file.
 571                         byte[] saltByteArray = new byte[32];
 572                         //noinspection ResultOfMethodCallIgnored
 573                         inputStream.read(saltByteArray);
 574
 575                         // Get the initialization vector from the import file.
 576                         byte[] initializationVector = new byte[12];
 577                         //noinspection ResultOfMethodCallIgnored
 578                         inputStream.read(initializationVector);
 579
 580                         // Convert the encryption password to a byte array.
 581                         byte[] encryptionPasswordByteArray = encryptionPasswordString.getBytes(StandardCharsets.UTF_8);
 582
 583                         // Append the salt to the encryption password byte array.  This protects against rainbow table attacks.
 584                         byte[] encryptionPasswordWithSaltByteArray = new byte[encryptionPasswordByteArray.length + saltByteArray.length];
 585                         System.arraycopy(encryptionPasswordByteArray, 0, encryptionPasswordWithSaltByteArray, 0, encryptionPasswordByteArray.length);
 586                         System.arraycopy(saltByteArray, 0, encryptionPasswordWithSaltByteArray, encryptionPasswordByteArray.length, saltByteArray.length);
 587
 588                         // Get a SHA-512 message digest.
 589                         MessageDigest messageDigest = MessageDigest.getInstance("SHA-512");
 590
 591                         // Hash the salted encryption password.  Otherwise, any characters after the 32nd character in the password are ignored.
 592                         byte[] hashedEncryptionPasswordWithSaltByteArray = messageDigest.digest(encryptionPasswordWithSaltByteArray);
 593
 594                         // Truncate the encryption password byte array to 256 bits (32 bytes).
 595                         byte[] truncatedHashedEncryptionPasswordWithSaltByteArray = Arrays.copyOf(hashedEncryptionPasswordWithSaltByteArray, 32);
 596
 597                         // Create an AES secret key from the encryption password byte array.
 598                         SecretKeySpec secretKey = new SecretKeySpec(truncatedHashedEncryptionPasswordWithSaltByteArray, "AES");
 599
 600                         // 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.
 601                         Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
 602
 603                         // Set the GCM tag length to be 128 bits (the maximum) and apply the initialization vector.
 604                         GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, initializationVector);
 605
 606                         // Initialize the cipher.
 607                         cipher.init(Cipher.DECRYPT_MODE, secretKey, gcmParameterSpec);
 608
 609                         // Create a cipher input stream.
 610                         CipherInputStream cipherInputStream = new CipherInputStream(inputStream, cipher);
 611
 612                         // 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.
 613                         int numberOfBytesRead;
 614                         byte[] decryptedBytes = new byte[16];
 615
 616
 617                         // Create a private temporary unencrypted import file.
 618                         File temporaryUnencryptedImportFile = File.createTempFile("temporary_unencrypted_import_file", null, getApplicationContext().getCacheDir());
 619
 620                         // Create an temporary unencrypted import file output stream.
 621                         FileOutputStream temporaryUnencryptedImportFileOutputStream = new FileOutputStream(temporaryUnencryptedImportFile);
 622
 623
 624                         // 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.
 625                         while ((numberOfBytesRead = cipherInputStream.read(decryptedBytes)) != -1) {
 626                             // Write the data to the temporary unencrypted import file output stream.
 627                             temporaryUnencryptedImportFileOutputStream.write(decryptedBytes, 0, numberOfBytesRead);
 628                         }
 629
 630
 631                         // Flush the temporary unencrypted import file output stream.
 632                         temporaryUnencryptedImportFileOutputStream.flush();
 633
 634                         // Close the streams.
 635                         temporaryUnencryptedImportFileOutputStream.close();
 636                         cipherInputStream.close();
 637                         inputStream.close();
 638
 639                         // Wipe the encryption data from memory.
 640                         //noinspection UnusedAssignment
 641                         encryptionPasswordString = "";
 642                         Arrays.fill(saltByteArray, (byte) 0);
 643                         Arrays.fill(initializationVector, (byte) 0);
 644                         Arrays.fill(encryptionPasswordByteArray, (byte) 0);
 645                         Arrays.fill(encryptionPasswordWithSaltByteArray, (byte) 0);
 646                         Arrays.fill(hashedEncryptionPasswordWithSaltByteArray, (byte) 0);
 647                         Arrays.fill(truncatedHashedEncryptionPasswordWithSaltByteArray, (byte) 0);
 648                         Arrays.fill(decryptedBytes, (byte) 0);
 649
 650                         // Create a temporary unencrypted import file input stream.
 651                         FileInputStream temporaryUnencryptedImportFileInputStream = new FileInputStream(temporaryUnencryptedImportFile);
 652
 653                         // Import the temporary unencrypted import file.
 654                         importStatus = importExportDatabaseHelper.importUnencrypted(temporaryUnencryptedImportFileInputStream, this);
 655
 656                         // Close the temporary unencrypted import file input stream.
 657                         temporaryUnencryptedImportFileInputStream.close();
 658
 659                         // Delete the temporary unencrypted import file.
 660                         //noinspection ResultOfMethodCallIgnored
 661                         temporaryUnencryptedImportFile.delete();
 662
 663                         // Restart Privacy Browser if successful.
 664                         if (importStatus.equals(ImportExportDatabaseHelper.IMPORT_SUCCESSFUL)) {
 665                             restartPrivacyBrowser();
 666                         }
 667                     } catch (Exception exception) {
 668                         // Update the import status.
 669                         importStatus = exception.toString();
 670                     }
 671                     break;
 672
 673                 case OPENPGP_ENCRYPTION:
 674                     try {
 675                         // Get a handle for the file provider directory.
 676                         fileProviderDirectory = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.file_provider_directory));
 677
 678                         // Create the file provider directory.  Any errors will be handled by the catch statement below.
 679                         //noinspection ResultOfMethodCallIgnored
 680                         fileProviderDirectory.mkdir();
 681
 682                         // Set the temporary PGP encrypted import file.
 683                         temporaryPgpEncryptedImportFile = File.createTempFile("temporary_pgp_encrypted_import_file", null, fileProviderDirectory);
 684
 685                         // Create a temporary PGP encrypted import file output stream.
 686                         FileOutputStream temporaryPgpEncryptedImportFileOutputStream = new FileOutputStream(temporaryPgpEncryptedImportFile);
 687
 688                         // Get an input stream for the file name.
 689                         InputStream inputStream = getContentResolver().openInputStream(Uri.parse(fileNameString));
 690
 691                         // Create a transfer byte array.
 692                         byte[] transferByteArray = new byte[1024];
 693
 694                         // Create an integer to track the number of bytes read.
 695                         int bytesRead;
 696
 697                         // Copy the input stream to the temporary PGP encrypted import file.
 698                         while ((bytesRead = inputStream.read(transferByteArray)) > 0) {
 699                             temporaryPgpEncryptedImportFileOutputStream.write(transferByteArray, 0, bytesRead);
 700                         }
 701
 702                         // Flush the temporary PGP encrypted import file output stream.
 703                         temporaryPgpEncryptedImportFileOutputStream.flush();
 704
 705                         // Close the streams.
 706                         inputStream.close();
 707                         temporaryPgpEncryptedImportFileOutputStream.close();
 708
 709                         // Create an decryption intent for OpenKeychain.
 710                         Intent openKeychainDecryptIntent = new Intent("org.sufficientlysecure.keychain.action.DECRYPT_DATA");
 711
 712                         // Include the URI to be decrypted.
 713                         openKeychainDecryptIntent.setData(FileProvider.getUriForFile(this, getString(R.string.file_provider), temporaryPgpEncryptedImportFile));
 714
 715                         // Allow OpenKeychain to read the file URI.
 716                         openKeychainDecryptIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
 717
 718                         // Send the intent to the OpenKeychain package.
 719                         openKeychainDecryptIntent.setPackage("org.sufficientlysecure.keychain");
 720
 721                         // Make it so.
 722                         startActivityForResult(openKeychainDecryptIntent, OPENPGP_IMPORT_RESULT_CODE);
 723
 724                         // Update the import status.
 725                         importStatus = ImportExportDatabaseHelper.IMPORT_SUCCESSFUL;
 726                     } catch (Exception exception) {
 727                         // Update the import status.
 728                         importStatus = exception.toString();
 729                     }
 730                     break;
 731             }
 732
 733             // Respond to the import status.
 734             if (!importStatus.equals(ImportExportDatabaseHelper.IMPORT_SUCCESSFUL)) {
 735                 // Display a snack bar with the import error.
 736                 Snackbar.make(fileNameEditText, getString(R.string.import_failed) + "  " + importStatus, Snackbar.LENGTH_INDEFINITE).show();
 737             }
 738         } else {  // Export is selected.
 739             // Export according to the encryption type.
 740             switch (encryptionSpinner.getSelectedItemPosition()) {
 741                 case NO_ENCRYPTION:
 742                     // Get the file name string.
 743                     String noEncryptionFileNameString = fileNameEditText.getText().toString();
 744
 745                     try {
 746                         // Get the export file output stream.
 747                         // A file may be opened directly once the minimum API >= 29.  <https://developer.android.com/reference/kotlin/android/content/ContentResolver#openfile>
 748                         OutputStream exportFileOutputStream = getContentResolver().openOutputStream(Uri.parse(noEncryptionFileNameString));
 749
 750                         // Export the unencrypted file.
 751                         String noEncryptionExportStatus = importExportDatabaseHelper.exportUnencrypted(exportFileOutputStream, this);
 752
 753                         // Display an export disposition snackbar.
 754                         if (noEncryptionExportStatus.equals(ImportExportDatabaseHelper.EXPORT_SUCCESSFUL)) {
 755                             Snackbar.make(fileNameEditText, getString(R.string.export_successful), Snackbar.LENGTH_SHORT).show();
 756                         } else {
 757                             Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + noEncryptionExportStatus, Snackbar.LENGTH_INDEFINITE).show();
 758                         }
 759                     } catch (FileNotFoundException fileNotFoundException) {
 760                         // Display a snackbar with the exception.
 761                         Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + fileNotFoundException, Snackbar.LENGTH_INDEFINITE).show();
 762                     }
 763                     break;
 764
 765                 case PASSWORD_ENCRYPTION:
 766                     try {
 767                         // Create a temporary unencrypted export file.
 768                         File temporaryUnencryptedExportFile = File.createTempFile("temporary_unencrypted_export_file", null, getApplicationContext().getCacheDir());
 769
 770                         // Create a temporary unencrypted export output stream.
 771                         FileOutputStream temporaryUnencryptedExportOutputStream = new FileOutputStream(temporaryUnencryptedExportFile);
 772
 773                         // Populate the temporary unencrypted export.
 774                         String passwordEncryptionExportStatus = importExportDatabaseHelper.exportUnencrypted(temporaryUnencryptedExportOutputStream, this);
 775
 776                         // Close the temporary unencrypted export output stream.
 777                         temporaryUnencryptedExportOutputStream.close();
 778
 779                         // Create an unencrypted export file input stream.
 780                         FileInputStream unencryptedExportFileInputStream = new FileInputStream(temporaryUnencryptedExportFile);
 781
 782                         // Get the encryption password.
 783                         String encryptionPasswordString = encryptionPasswordEditText.getText().toString();
 784
 785                         // Initialize a secure random number generator.
 786                         SecureRandom secureRandom = new SecureRandom();
 787
 788                         // Get a 256 bit (32 byte) random salt.
 789                         byte[] saltByteArray = new byte[32];
 790                         secureRandom.nextBytes(saltByteArray);
 791
 792                         // Convert the encryption password to a byte array.
 793                         byte[] encryptionPasswordByteArray = encryptionPasswordString.getBytes(StandardCharsets.UTF_8);
 794
 795                         // Append the salt to the encryption password byte array.  This protects against rainbow table attacks.
 796                         byte[] encryptionPasswordWithSaltByteArray = new byte[encryptionPasswordByteArray.length + saltByteArray.length];
 797                         System.arraycopy(encryptionPasswordByteArray, 0, encryptionPasswordWithSaltByteArray, 0, encryptionPasswordByteArray.length);
 798                         System.arraycopy(saltByteArray, 0, encryptionPasswordWithSaltByteArray, encryptionPasswordByteArray.length, saltByteArray.length);
 799
 800                         // Get a SHA-512 message digest.
 801                         MessageDigest messageDigest = MessageDigest.getInstance("SHA-512");
 802
 803                         // Hash the salted encryption password.  Otherwise, any characters after the 32nd character in the password are ignored.
 804                         byte[] hashedEncryptionPasswordWithSaltByteArray = messageDigest.digest(encryptionPasswordWithSaltByteArray);
 805
 806                         // Truncate the encryption password byte array to 256 bits (32 bytes).
 807                         byte[] truncatedHashedEncryptionPasswordWithSaltByteArray = Arrays.copyOf(hashedEncryptionPasswordWithSaltByteArray, 32);
 808
 809                         // Create an AES secret key from the encryption password byte array.
 810                         SecretKeySpec secretKey = new SecretKeySpec(truncatedHashedEncryptionPasswordWithSaltByteArray, "AES");
 811
 812                         // Generate a random 12 byte initialization vector.  According to NIST, a 12 byte initialization vector is more secure than a 16 byte one.
 813                         byte[] initializationVector = new byte[12];
 814                         secureRandom.nextBytes(initializationVector);
 815
 816                         // 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.
 817                         Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
 818
 819                         // Set the GCM tag length to be 128 bits (the maximum) and apply the initialization vector.
 820                         GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, initializationVector);
 821
 822                         // Initialize the cipher.
 823                         cipher.init(Cipher.ENCRYPT_MODE, secretKey, gcmParameterSpec);
 824
 825                         // Get the file name string.
 826                         String passwordEncryptionFileNameString = fileNameEditText.getText().toString();
 827
 828                         // Get the export file output stream.
 829                         OutputStream exportFileOutputStream = getContentResolver().openOutputStream(Uri.parse(passwordEncryptionFileNameString));
 830
 831                         // Add the salt and the initialization vector to the export file output stream.
 832                         exportFileOutputStream.write(saltByteArray);
 833                         exportFileOutputStream.write(initializationVector);
 834
 835                         // Create a cipher output stream.
 836                         CipherOutputStream cipherOutputStream = new CipherOutputStream(exportFileOutputStream, cipher);
 837
 838                         // 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.
 839                         int numberOfBytesRead;
 840                         byte[] encryptedBytes = new byte[16];
 841
 842                         // 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.
 843                         while ((numberOfBytesRead = unencryptedExportFileInputStream.read(encryptedBytes)) != -1) {
 844                             // Write the data to the cipher output stream.
 845                             cipherOutputStream.write(encryptedBytes, 0, numberOfBytesRead);
 846                         }
 847
 848                         // Close the streams.
 849                         cipherOutputStream.flush();
 850                         cipherOutputStream.close();
 851                         exportFileOutputStream.close();
 852                         unencryptedExportFileInputStream.close();
 853
 854                         // Wipe the encryption data from memory.
 855                         //noinspection UnusedAssignment
 856                         encryptionPasswordString = "";
 857                         Arrays.fill(saltByteArray, (byte) 0);
 858                         Arrays.fill(encryptionPasswordByteArray, (byte) 0);
 859                         Arrays.fill(encryptionPasswordWithSaltByteArray, (byte) 0);
 860                         Arrays.fill(hashedEncryptionPasswordWithSaltByteArray, (byte) 0);
 861                         Arrays.fill(truncatedHashedEncryptionPasswordWithSaltByteArray, (byte) 0);
 862                         Arrays.fill(initializationVector, (byte) 0);
 863                         Arrays.fill(encryptedBytes, (byte) 0);
 864
 865                         // Delete the temporary unencrypted export file.
 866                         //noinspection ResultOfMethodCallIgnored
 867                         temporaryUnencryptedExportFile.delete();
 868
 869                         // Display an export disposition snackbar.
 870                         if (passwordEncryptionExportStatus.equals(ImportExportDatabaseHelper.EXPORT_SUCCESSFUL)) {
 871                             Snackbar.make(fileNameEditText, getString(R.string.export_successful), Snackbar.LENGTH_SHORT).show();
 872                         } else {
 873                             Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + passwordEncryptionExportStatus, Snackbar.LENGTH_INDEFINITE).show();
 874                         }
 875                     } catch (Exception exception) {
 876                         // Display a snackbar with the exception.
 877                         Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + exception, Snackbar.LENGTH_INDEFINITE).show();
 878                     }
 879                     break;
 880
 881                 case OPENPGP_ENCRYPTION:
 882                     try {
 883                         // Get a handle for the file provider directory.
 884                         fileProviderDirectory = new File(getApplicationContext().getCacheDir() + "/" + getString(R.string.file_provider_directory));
 885
 886                         // Create the file provider directory.  Any errors will be handled by the catch statement below.
 887                         //noinspection ResultOfMethodCallIgnored
 888                         fileProviderDirectory.mkdir();
 889
 890                         // Set the temporary pre-encrypted export file.
 891                         temporaryPreEncryptedExportFile = new File(fileProviderDirectory + "/" + getString(R.string.settings) + " " + BuildConfig.VERSION_NAME + ".pbs");
 892
 893                         // Delete the temporary pre-encrypted export file if it already exists.
 894                         if (temporaryPreEncryptedExportFile.exists()) {
 895                             //noinspection ResultOfMethodCallIgnored
 896                             temporaryPreEncryptedExportFile.delete();
 897                         }
 898
 899                         // Create a temporary pre-encrypted export output stream.
 900                         FileOutputStream temporaryPreEncryptedExportOutputStream = new FileOutputStream(temporaryPreEncryptedExportFile);
 901
 902                         // Populate the temporary pre-encrypted export file.
 903                         String openpgpEncryptionExportStatus = importExportDatabaseHelper.exportUnencrypted(temporaryPreEncryptedExportOutputStream, this);
 904
 905                         // Flush the temporary pre-encryption export output stream.
 906                         temporaryPreEncryptedExportOutputStream.flush();
 907
 908                         // Close the temporary pre-encryption export output stream.
 909                         temporaryPreEncryptedExportOutputStream.close();
 910
 911                         // Display an export error snackbar if the temporary pre-encrypted export failed.
 912                         if (!openpgpEncryptionExportStatus.equals(ImportExportDatabaseHelper.EXPORT_SUCCESSFUL)) {
 913                             Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + openpgpEncryptionExportStatus, Snackbar.LENGTH_INDEFINITE).show();
 914                         }
 915
 916                         // Create an encryption intent for OpenKeychain.
 917                         Intent openKeychainEncryptIntent = new Intent("org.sufficientlysecure.keychain.action.ENCRYPT_DATA");
 918
 919                         // Include the temporary unencrypted export file URI.
 920                         openKeychainEncryptIntent.setData(FileProvider.getUriForFile(this, getString(R.string.file_provider), temporaryPreEncryptedExportFile));
 921
 922                         // Allow OpenKeychain to read the file URI.
 923                         openKeychainEncryptIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
 924
 925                         // Send the intent to the OpenKeychain package.
 926                         openKeychainEncryptIntent.setPackage("org.sufficientlysecure.keychain");
 927
 928                         // Make it so.
 929                         startActivityForResult(openKeychainEncryptIntent, OPENPGP_EXPORT_RESULT_CODE);
 930                     } catch (Exception exception) {
 931                         // Display a snackbar with the exception.
 932                         Snackbar.make(fileNameEditText, getString(R.string.export_failed) + "  " + exception, Snackbar.LENGTH_INDEFINITE).show();
 933                     }
 934                     break;
 935             }
 936         }
 937     }
 938
 939     private void restartPrivacyBrowser() {
 940         // Create an intent to restart Privacy Browser.
 941         Intent restartIntent = getParentActivityIntent();
 942
 943         // Assert that the intent is not null to remove the lint error below.
 944         assert restartIntent != null;
 945
 946         // `Intent.FLAG_ACTIVITY_CLEAR_TASK` removes all activities from the stack.  It requires `Intent.FLAG_ACTIVITY_NEW_TASK`.
 947         restartIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
 948
 949         // Create a restart handler.
 950         Handler restartHandler = new Handler();
 951
 952         // Create a restart runnable.
 953         Runnable restartRunnable =  () -> {
 954             // Restart Privacy Browser.
 955             startActivity(restartIntent);
 956
 957             // Kill this instance of Privacy Browser.  Otherwise, the app exhibits sporadic behavior after the restart.
 958             System.exit(0);
 959         };
 960
 961         // Restart Privacy Browser after 150 milliseconds to allow enough time for the preferences to be saved.
 962         restartHandler.postDelayed(restartRunnable, 150);
 963     }
 964 }