public function isSuccessful()
    {
        # Validate the Hash
        $hashSecretWord = $this->data['secretWord']; # Input your secret word
        $hashSid = $this->data['accountNumber']; #Input your seller ID (2Checkout account number)
        $hashOrder = $this->data['sale_id'];
        $hashInvoice = $this->data['invoice_id'];
        $StringToHash = strtoupper(md5($hashOrder.$hashSid.$hashInvoice.$hashSecretWord));

        return $StringToHash == $this->data['md5_hash'];
    }