/**
  * Method validates HPP response hash.
  *
  * @param HppResponse $hppResponse
  * @param string $secret
  */
 public static function validateResponse(HppResponse $hppResponse, $secret)
 {
     self::Initialise();
     if (!$hppResponse->isHashValid($secret)) {
         self::$logger->error("HppResponse contains an invalid security hash.");
         throw new RealexValidationException("HppResponse contains an invalid security hash", array("HppResponse contains an invalid security hash"));
     }
 }