class SignGenerator {

    // Merchant secure data - merchant key
    private $key = "1234567812345678123456781234567812345678123456781234567812345678";

    // Transaction data
    private $mid;
    private $amount;
    private $currencyAplhaCode;
    private $msTxnId;
    private $firstName;
    private $familyName;
    private $timestamp;

    // Sign config
    private $_mode = MCRYPT_MODE_CBC;
    private $_cipher;
    private $_paddingType;


    public function __construct($mid,$amount,$currency,$mstxnid,$firstname,$familyname,$timestamp){
        $this->_cipher = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', $this->_mode, '');
        $this->_paddingType = 'PKCS7';

        $this->mid = $mid;
        $this->amount = $amount;
        $this->currencyAplhaCode = $currency;
        $this->msTxnId = $mstxnid;
        $this->firstName = $firstname;
        $this->familyName = $familyname;
        $this->timestamp = $timestamp;

        $this->iv = $mid.strrev($mid);
    }

    public function getHexKey(){
        return pack("H*" , $this->key );
    }

    /*
     * WORK IN PHP OR NEWER
    public function getHexKey(){
        $hKey = "";
        for($i=0;$i<strlen($this->key);$i=$i+2){
            $hKey .= hex2bin($this->key[$i].$this->key[$i+1]);
        }
        return $hKey;
    }
    */

    public function getPlainText(){
        return $this->mid.$this->amount.$this->currencyAplhaCode.$this->msTxnId.$this->firstName.$this->familyName.$this->timestamp;
    }

    private function getData(){
        return sha1($this->getPlainText(),true);
    }

    public function signTransaction(){
        if ($this->_paddingType == 'PKCS7'){
            $data = $this->AddPadding($this->getData());
        }

        mcrypt_generic_init($this->_cipher, $this->getHexKey(), $this->iv);
        $result = mcrypt_generic($this->_cipher, $data);
        mcrypt_generic_deinit($this->_cipher);

        return strtoupper(substr(bin2hex($result),0,32));
    }

    private function AddPadding($data){
      $block = mcrypt_get_block_size('des', $this->_mode);
      $pad   = $block - (strlen($data) % $block);
      $data .= str_repeat(chr($pad), $pad);
      return $data;
    }

}