:right-sidebar: True

Checksum
===================================================================

.. currentmodule:: gi.repository.GLib


.. versionadded:: 2.16




.. class:: Checksum(**kwargs)
   :no-contents-entry:






GLib provides a generic API for computing checksums (or ‘digests’)
for a sequence of arbitrary bytes, using various hashing algorithms
like MD5, SHA-1 and SHA-256. Checksums are commonly used in various
environments and specifications.

To create a new ``GChecksum``\, use :obj:`~gi.repository.GLib.Checksum.new`\. To free
a ``GChecksum``\, use :obj:`~gi.repository.GLib.Checksum.free`\.

GLib supports incremental checksums using the ``GChecksum`` data
structure, by calling :obj:`~gi.repository.GLib.Checksum.update` as long as there’s data
available and then using :obj:`~gi.repository.GLib.Checksum.get_string` or
:obj:`~gi.repository.GLib.Checksum.get_digest` to compute the checksum and return it
either as a string in hexadecimal form, or as a raw sequence of bytes. To
compute the checksum for binary blobs and nul-terminated strings in
one go, use the convenience functions :obj:`~gi.repository.GLib.compute_checksum_for_data`
and :obj:`~gi.repository.GLib.compute_checksum_for_string`\, respectively.


Constructors
------------

.. rst-class:: interim-class

.. class:: Checksum
   :no-index:


   .. classmethod:: new(checksum_type: ~gi.repository.GLib.ChecksumType) -> ~gi.repository.GLib.Checksum | None

      Creates a new :obj:`~gi.repository.GLib.Checksum`\, using the checksum algorithm ``checksum_type``\.
      If the ``checksum_type`` is not known, :const:`None` is returned.
      A :obj:`~gi.repository.GLib.Checksum` can be used to compute the checksum, or digest, of an
      arbitrary binary blob, using different hashing algorithms.

      A :obj:`~gi.repository.GLib.Checksum` works by feeding a binary blob through :func:`~gi.repository.GLib.Checksum.update`
      until there is data to be checked; the digest can then be extracted
      using :func:`~gi.repository.GLib.Checksum.get_string`, which will return the checksum as a
      hexadecimal string; or :func:`~gi.repository.GLib.Checksum.get_digest`, which will return a
      vector of raw bytes. Once either :func:`~gi.repository.GLib.Checksum.get_string` or
      :func:`~gi.repository.GLib.Checksum.get_digest` have been called on a :obj:`~gi.repository.GLib.Checksum`\, the checksum
      will be closed and it won't be possible to call :func:`~gi.repository.GLib.Checksum.update`
      on it anymore.


      .. versionadded:: 2.16





      :param checksum_type: the desired type of checksum








Methods
-------

.. rst-class:: interim-class

.. class:: Checksum
   :no-index:


   .. method:: free() -> None

      Frees the memory allocated for ``checksum``\.


      .. versionadded:: 2.16








   .. method:: get_string() -> str

      Gets the digest as a hexadecimal string.

      Once this function has been called the :obj:`~gi.repository.GLib.Checksum` can no longer be
      updated with :func:`~gi.repository.GLib.Checksum.update`.

      The hexadecimal characters will be lower case.


      .. versionadded:: 2.16








   .. method:: reset() -> None

      Resets the state of the ``checksum`` back to its initial state.


      .. versionadded:: 2.18








   .. classmethod:: type_get_length() -> int

      Gets the length in bytes of digests of type ``checksum_type``


      .. versionadded:: 2.16








   .. method:: update(data: list[int]) -> None

      Feeds ``data`` into an existing :obj:`~gi.repository.GLib.Checksum`\. The checksum must still be
      open, that is :func:`~gi.repository.GLib.Checksum.get_string` or :func:`~gi.repository.GLib.Checksum.get_digest` must
      not have been called on ``checksum``\.


      .. versionadded:: 2.16





      :param data: buffer used to compute the checksum