Add information dialog about the new encryption

app/src/main/java/org/shadowice/flocke/andotp/Activities/BackupActivity.java

@@ -188,6 +188,23 @@ public class BackupActivity extends BaseActivity {
 
         replace = v.findViewById(R.id.backup_replace);
 
+        if (! settings.getNewBackupFormatDialogShown()) {
+            showNewBackupInfo();
+        }
+    }
+
+    private void showNewBackupInfo() {
+        AlertDialog.Builder builder = new AlertDialog.Builder(this);
+        builder.setTitle(R.string.backup_new_format_dialog_title)
+                .setMessage(R.string.backup_new_format_dialog_msg)
+                .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialogInterface, int i) {
+                        settings.setNewBackupFormatDialogShown(true);
+                    }
+                })
+                .create()
+                .show();
     }
 
     // End with a result

app/src/main/java/org/shadowice/flocke/andotp/Utilities/Settings.java

@@ -493,6 +493,14 @@ public class Settings {
         setBoolean(R.string.settings_key_last_used_dialog_shown, value);
     }
 
+    public boolean getNewBackupFormatDialogShown() {
+        return getBoolean(R.string.settings_key_new_backup_format_dialog_shown, false);
+    }
+
+    public void setNewBackupFormatDialogShown(boolean value) {
+        setBoolean(R.string.settings_key_new_backup_format_dialog_shown, value);
+    }
+
     public boolean getAndroidBackupServiceEnabled() {
         return getBoolean(R.string.settings_key_enable_android_backup_service, true);
     }

app/src/main/res/values/settings.xml

@@ -36,6 +36,7 @@
     <string name="settings_key_openpgp_key_encrypt" translatable="false">pref_openpgp_key_encrypt</string>
     <string name="settings_key_openpgp_key_sign" translatable="false">pref_openpgp_key_sign</string>
     <string name="settings_key_openpgp_verify" translatable="false">pref_openpgp_verify</string>
+    <string name="settings_key_new_backup_format_dialog_shown" translatable="false">pref_new_backup_dialog_shown</string>
 
     <string name="settings_key_security_backup_warning" translatable="false">pref_security_backup_warning_shown</string>
     <string name="settings_key_sort_mode" translatable="false">pref_sort_mode</string>

app/src/main/res/values/strings_backup.xml

@@ -21,7 +21,8 @@
     <string name="backup_desc_export_openpgp">Backup all accounts in an OpenPGP-encrypted JSON file</string>
     <string name="backup_desc_import_plain">Restore accounts from a plain-text JSON file</string>
     <string name="backup_desc_import_crypt">Restore accounts from a password-protected JSON file</string>
-    <string name="backup_desc_import_crypt_old">Restore accounts from a password-protected JSON file using the old, insecure encryption</string>
+    <string name="backup_desc_import_crypt_old">Restore accounts from a password-protected JSON file
+        created with an <b>andOTP version lower than 0.6.3</b></string>
     <string name="backup_desc_import_openpgp">Restore accounts from an OpenPGP-encrypted JSON file</string>
 
     <string name="backup_desc_crypt_setup">Failed to load the backup password from the <b>Settings</b>,
@@ -63,6 +64,12 @@
     <string name="backup_receiver_custom_encryption_failed">Password/PIN based encryption not
         supported with broadcast backup</string>
 
+    <string name="backup_new_format_dialog_title">New encryption method</string>
+    <string name="backup_new_format_dialog_msg">Since version 0.6.3 of andOTP, a <b>new and improved
+        encryption method</b> is used for password-protected backups. The old backups can still be
+        imported, but it is <b>highly recommended to create new backups with the improved
+        encryption</b>.\n\nThis message will not be shown again.</string>
+
     <!-- Notification channels -->
     <string name="notification_channel_name_backup_failed">Automatic backup failed</string>
     <string name="notification_channel_name_backup_success">Automatic backup successful</string>