code: public static PrivateKey readPrivateKey(final File root, final String directory,
  		final String fileName) throws NoSuchAlgorithmException, InvalidKeySpecException,
  		NoSuchProviderException, IOException
  	{
  
  		final File privatekeyDir = new File(root, directory);
  		final File privatekeyFile = new File(privatekeyDir, fileName);
  
  		final PrivateKey privateKey = PrivateKeyReader.readPrivateKey(privatekeyFile);
  		return privateKey;
  	}
docs: Constructs from the given root, parent directory and file name the file and reads the private
  key.
  
  @param root
  the root directory of the parent directory
  @param directory
  the parent directory of the private key file
  @param fileName
  the file name of the file that contains the private key
  @return the private key
  @throws NoSuchAlgorithmException
  is thrown if instantiation of the SecretKeyFactory object fails.
  @throws InvalidKeySpecException
  is thrown if generation of the SecretKey object fails.
  @throws NoSuchProviderException
  the no such provider exception
  @throws IOException
  Signals that an I/O exception has occurred.