code: protected PrivateKey getSigningPrivateKey() throws Exception {
          val samlIdp = casProperties.getAuthn().getSamlIdp();
          val signingKey = samlIdPMetadataLocator.getSigningKey();
          val privateKeyFactoryBean = new PrivateKeyFactoryBean();
          privateKeyFactoryBean.setLocation(signingKey);
          privateKeyFactoryBean.setAlgorithm(samlIdp.getMetadata().getPrivateKeyAlgName());
          privateKeyFactoryBean.setSingleton(false);
          LOGGER.debug("Locating signature signing key from [{}]", signingKey);
          return privateKeyFactoryBean.getObject();
      }
docs: Gets signing private key.
  
  @return the signing private key
  @throws Exception the exception