godot-docs/classes/class_aescontext.rst

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.. _class_AESContext:

AESContext
==========

**Inherits:** :ref:`Reference<class_Reference>` **<** :ref:`Object<class_Object>`

Interface to low level AES encryption features.

.. rst-class:: classref-introduction-group

Description
-----------

This class provides access to AES encryption/decryption of raw data. Both AES-ECB and AES-CBC mode are supported.

::

    extends Node
    
    var aes = AESContext.new()
    
    func _ready():
        var key = "My secret key!!!" # Key must be either 16 or 32 bytes.
        var data = "My secret text!!" # Data size must be multiple of 16 bytes, apply padding if needed.
        # Encrypt ECB
        aes.start(AESContext.MODE_ECB_ENCRYPT, key.to_utf8())
        var encrypted = aes.update(data.to_utf8())
        aes.finish()
        # Decrypt ECB
        aes.start(AESContext.MODE_ECB_DECRYPT, key.to_utf8())
        var decrypted = aes.update(encrypted)
        aes.finish()
        # Check ECB
        assert(decrypted == data.to_utf8())
    
        var iv = "My secret iv!!!!" # IV must be of exactly 16 bytes.
        # Encrypt CBC
        aes.start(AESContext.MODE_CBC_ENCRYPT, key.to_utf8(), iv.to_utf8())
        encrypted = aes.update(data.to_utf8())
        aes.finish()
        # Decrypt CBC
        aes.start(AESContext.MODE_CBC_DECRYPT, key.to_utf8(), iv.to_utf8())
        decrypted = aes.update(encrypted)
        aes.finish()
        # Check CBC
        assert(decrypted == data.to_utf8())

.. rst-class:: classref-reftable-group

Methods
-------

.. table::
   :widths: auto

   +-------------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | void                                      | :ref:`finish<class_AESContext_method_finish>` **(** **)**                                                                                                                                                     |
   +-------------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`PoolByteArray<class_PoolByteArray>` | :ref:`get_iv_state<class_AESContext_method_get_iv_state>` **(** **)**                                                                                                                                         |
   +-------------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`Error<enum_@GlobalScope_Error>`     | :ref:`start<class_AESContext_method_start>` **(** :ref:`Mode<enum_AESContext_Mode>` mode, :ref:`PoolByteArray<class_PoolByteArray>` key, :ref:`PoolByteArray<class_PoolByteArray>` iv=PoolByteArray(  ) **)** |
   +-------------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`PoolByteArray<class_PoolByteArray>` | :ref:`update<class_AESContext_method_update>` **(** :ref:`PoolByteArray<class_PoolByteArray>` src **)**                                                                                                       |
   +-------------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

.. rst-class:: classref-section-separator

----

.. rst-class:: classref-descriptions-group

Enumerations
------------

.. _enum_AESContext_Mode:

.. rst-class:: classref-enumeration

enum **Mode**:

.. _class_AESContext_constant_MODE_ECB_ENCRYPT:

.. rst-class:: classref-enumeration-constant

:ref:`Mode<enum_AESContext_Mode>` **MODE_ECB_ENCRYPT** = ``0``

AES electronic codebook encryption mode.

.. _class_AESContext_constant_MODE_ECB_DECRYPT:

.. rst-class:: classref-enumeration-constant

:ref:`Mode<enum_AESContext_Mode>` **MODE_ECB_DECRYPT** = ``1``

AES electronic codebook decryption mode.

.. _class_AESContext_constant_MODE_CBC_ENCRYPT:

.. rst-class:: classref-enumeration-constant

:ref:`Mode<enum_AESContext_Mode>` **MODE_CBC_ENCRYPT** = ``2``

AES cipher blocker chaining encryption mode.

.. _class_AESContext_constant_MODE_CBC_DECRYPT:

.. rst-class:: classref-enumeration-constant

:ref:`Mode<enum_AESContext_Mode>` **MODE_CBC_DECRYPT** = ``3``

AES cipher blocker chaining decryption mode.

.. _class_AESContext_constant_MODE_MAX:

.. rst-class:: classref-enumeration-constant

:ref:`Mode<enum_AESContext_Mode>` **MODE_MAX** = ``4``

Maximum value for the mode enum.

.. rst-class:: classref-section-separator

----

.. rst-class:: classref-descriptions-group

Method Descriptions
-------------------

.. _class_AESContext_method_finish:

.. rst-class:: classref-method

void **finish** **(** **)**

Close this AES context so it can be started again. See :ref:`start<class_AESContext_method_start>`.

.. rst-class:: classref-item-separator

----

.. _class_AESContext_method_get_iv_state:

.. rst-class:: classref-method

:ref:`PoolByteArray<class_PoolByteArray>` **get_iv_state** **(** **)**

Get the current IV state for this context (IV gets updated when calling :ref:`update<class_AESContext_method_update>`). You normally don't need this function.

\ **Note:** This function only makes sense when the context is started with :ref:`MODE_CBC_ENCRYPT<class_AESContext_constant_MODE_CBC_ENCRYPT>` or :ref:`MODE_CBC_DECRYPT<class_AESContext_constant_MODE_CBC_DECRYPT>`.

.. rst-class:: classref-item-separator

----

.. _class_AESContext_method_start:

.. rst-class:: classref-method

:ref:`Error<enum_@GlobalScope_Error>` **start** **(** :ref:`Mode<enum_AESContext_Mode>` mode, :ref:`PoolByteArray<class_PoolByteArray>` key, :ref:`PoolByteArray<class_PoolByteArray>` iv=PoolByteArray(  ) **)**

Start the AES context in the given ``mode``. A ``key`` of either 16 or 32 bytes must always be provided, while an ``iv`` (initialization vector) of exactly 16 bytes, is only needed when ``mode`` is either :ref:`MODE_CBC_ENCRYPT<class_AESContext_constant_MODE_CBC_ENCRYPT>` or :ref:`MODE_CBC_DECRYPT<class_AESContext_constant_MODE_CBC_DECRYPT>`.

.. rst-class:: classref-item-separator

----

.. _class_AESContext_method_update:

.. rst-class:: classref-method

:ref:`PoolByteArray<class_PoolByteArray>` **update** **(** :ref:`PoolByteArray<class_PoolByteArray>` src **)**

Run the desired operation for this AES context. Will return a :ref:`PoolByteArray<class_PoolByteArray>` containing the result of encrypting (or decrypting) the given ``src``. See :ref:`start<class_AESContext_method_start>` for mode of operation.

\ **Note:** The size of ``src`` must be a multiple of 16. Apply some padding if needed.

.. |virtual| replace:: :abbr:`virtual (This method should typically be overridden by the user to have any effect.)`
.. |const| replace:: :abbr:`const (This method has no side effects. It doesn't modify any of the instance's member variables.)`
.. |vararg| replace:: :abbr:`vararg (This method accepts any number of arguments after the ones described here.)`
.. |static| replace:: :abbr:`static (This method doesn't need an instance to be called, so it can be called directly using the class name.)`