OSSL_PKEY_PARAM_RSA_DIGEST_PROPS
param_propq = OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_RSA_DIGEST_PROPS);
OSSL_PKEY_PARAM_RSA_DIGEST_PROPS, mdprops);
OSSL_PARAM_utf8_string(OSSL_PKEY_PARAM_RSA_DIGEST_PROPS, NULL, 0), \