public function generateDefaults( $secret ) {

		//generate timestamp if not set
		if ( is_null( $this->timeStamp ) ) {
			$this->timeStamp = GenerationUtils::generateTimestamp();
		}

		//generate order ID if not set
		if ( is_null( $this->orderId ) ) {
			$this->orderId = GenerationUtils::generateOrderId();
		}

		//generate hash
		$this->hash( $secret );

		return $this;
	}