protected function loadFile($filePath)
	{
		if (!file_exists($filePath) || !is_readable($filePath))
		{
			throw new \UnexpectedValueException(sprintf('Unable to open the "%s" file', $filePath));
		}
			
		$key = @file_get_contents($filePath);
			
		if (!is_string($key) || 0 === strlen($key))
		{
			throw new \UnexpectedValueException(sprintf('File "%s" appears to be empty', $filePath));
		}
		
		return $key;
	}