def __init__(self, hashAlg, mgf, label=None):
self._param = PyKCS11.LowLevel.CK_RSA_PKCS_OAEP_PARAMS()<EOL>self._param.hashAlg = hashAlg<EOL>self._param.mgf = mgf<EOL>self._source = None<EOL>self._param.src = CKZ_DATA_SPECIFIED<EOL>if label:<EOL><INDENT>self._source = ckbytelist(label)<EOL>self._param.ulSourceDataLen = len(self._source)<EOL><DEDENT>else:<EOL><INDENT>self._param.ulSourceDataLen = <NUM_LIT:0><EOL><DEDENT>self._param.pSourceData = self._source<EOL>self._mech = PyKCS11.LowLevel.CK_MECHANISM()<EOL>self._mech.mechanism = CKM_RSA_PKCS_OAEP<EOL>self._mech.pParameter = self._param<EOL>self._mech.ulParameterLen = PyKCS11.LowLevel.CK_RSA_PKCS_OAEP_PARAMS_LENGTH<EOL>
:param hashAlg: the hash algorithm to use (like `CKM_SHA256`)
:param mgf: the mask generation function to use (like
  `CKG_MGF1_SHA256`)
:param label: the (optional) label to use