Symmetric Functions
===================

.. c:function:: int wally_symmetric_key_from_seed(const unsigned char *bytes, size_t bytes_len, unsigned char *bytes_out, size_t len)

   
   Create a new symmetric parent key from entropy.
   
   :param bytes: Entropy to use.
   :param bytes_len: Size of ``bytes`` in bytes. Must be one of `BIP32_ENTROPY_LEN_128`, `BIP32_ENTROPY_LEN_256` or `BIP32_ENTROPY_LEN_512`.
   :param bytes_out: Destination for the resulting parent key.
   :param len: Size of ``bytes_out``. Must be `HMAC_SHA512_LEN`.

   :return: See :ref:`error-codes`


.. c:function:: int wally_symmetric_key_from_parent(const unsigned char *bytes, size_t bytes_len, uint32_t version, const unsigned char *label, size_t label_len, unsigned char *bytes_out, size_t len)

   
   
   Create a new child symmetric key from a parent key.
   
   :param bytes: Parent key to use.
   :param bytes_len: Size of ``bytes`` in bytes. Must be `HMAC_SHA512_LEN`.
   :param version: Version byte to prepend to ``label``. Must be zero.
   :param label: Label to use for the child.
   :param label_len: Size of ``label`` in bytes.
   :param bytes_out: Destination for the resulting key.
   :param len: Size of ``bytes_out``. Must be `HMAC_SHA512_LEN`.

   :return: See :ref:`error-codes`