def __init__(self, mecha, hashAlg, mgf, sLen):
self._param = PyKCS11.LowLevel.CK_RSA_PKCS_PSS_PARAMS()<EOL>self._param.hashAlg = hashAlg<EOL>self._param.mgf = mgf<EOL>self._param.sLen = sLen<EOL>self._mech = PyKCS11.LowLevel.CK_MECHANISM()<EOL>self._mech.mechanism = mecha<EOL>self._mech.pParameter = self._param<EOL>self._mech.ulParameterLen = PyKCS11.LowLevel.CK_RSA_PKCS_PSS_PARAMS_LENGTH<EOL>
:param mecha: the mechanism to use (like
  `CKM_SHA384_RSA_PKCS_PSS`)
:param hashAlg: the hash algorithm to use (like `CKM_SHA384`)
:param mgf: the mask generation function to use (like
  `CKG_MGF1_SHA384`)
:param sLen: length, in bytes, of the salt value used in the PSS
  encoding (like 0 or the message length)