godot-docs/tutorials/io/encrypting_save_games.rst

.. _doc_encrypting_save_games:

Encrypting save games
=====================

Why?
----

The class :ref:`File <class_File>` can open a file at a
location and read/write data (integers, strings and variants). 
It also supports encryption.
To create an encrypted file, a passphrase must be provided, like this:

.. tabs::
 .. code-tab:: gdscript GDScript

    var f = File.new()
    var err = f.open_encrypted_with_pass("user://savedata.bin", File.WRITE, "mypass")
    f.store_var(game_state)
    f.close()

 .. code-tab:: csharp

    var f = new File();
    var err = f.OpenEncryptedWithPass("user://savedata.bin", (int)File.ModeFlags.Write, "mypass");
    f.StoreVar(gameState);
    f.Close();

This will make the file unreadable to users, but will still not prevent
them sharing save files. To solve this, use the device unique id or
some unique user identifier, for example:

.. tabs::
 .. code-tab:: gdscript GDScript

    var f = File.new()
    var err = f.open_encrypted_with_pass("user://savedata.bin", File.WRITE, OS.get_unique_id())
    f.store_var(game_state)
    f.close()

 .. code-tab:: csharp

    var f = new File();
    var err = f.OpenEncryptedWithPass("user://savedata.bin", (int)File.ModeFlags.Write, OS.GetUniqueId());
    f.StoreVar(gameState);
    f.Close();

Note that ``OS.get_unique_ID()`` only works on iOS and Android.

This is all! Thanks for your cooperation, citizen.