.. _mozilla_projects_nss_reference_fc_unwrapkey:

FC_UnwrapKey
============

`Name <#name>`__
~~~~~~~~~~~~~~~~

.. container::

   FC_UnwrapKey - unwrap a key

`Syntax <#syntax>`__
~~~~~~~~~~~~~~~~~~~~

.. container::

   .. code::

      CK_RV FC_UnwrapKey(
        CK_SESSION_HANDLE hSession,
        CK_MECHANISM_PTR pMechanism,
        CK_OBJECT_HANDLE hUnwrappingKey,
        CK_BYTE_PTR pWrappedKey,
        CK_ULONG usWrappedKeyLen,
        CK_ATTRIBUTE_PTR pTemplate,
        CK_ULONG usAttributeCount,
        CK_OBJECT_HANDLE_PTR phKey
      );

`Parameters <#parameters>`__
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. container::

   ``hSession``
      [in] session handle.
   ``pMechanism``
      [in] pointer to the mechanism to use.
   ``hUnwrappingKey``
      [in] handle of the ket to use for unwrapping.
   ``pWrappedKey``
      [in] pointer to the wrapped key.
   ``usWrappedKeyLen``
      [in] length of the wrapped key.
   ``pTemplate``
      [in] pointer to the list of attributes for the unwrapped key.
   ``usAttributeCount``
      [in] number of attributes in the template.
   ``phKey``
      [out] pointer to the location to receive the handle of the unwrapped key.

`Description <#description>`__
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. container::

   ``FC_UnwrapKey`` unwraps (decrypts) a key and creates a new key opbject. If ``pWrappedKey`` is
   NULL the length of the wrapped key is returned in ``pusWrappedKeyLen`` and FC_UnwrapKey may be
   called again with ``pWrappedKey`` set to retrieve the wrapped key.

   A user must log into the token (to assume the NSS User role) before calling ``FC_UnwrapKey``.


`Return value <#return_value>`__
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

`Examples <#examples>`__
~~~~~~~~~~~~~~~~~~~~~~~~


`See also <#see_also>`__
~~~~~~~~~~~~~~~~~~~~~~~~

.. container::

   -  `NSC_UnwrapKey </en-US/NSC_UnwrapKey>`__