title: PayUMoney integration - How to calculate hash for comparing with response?
body: <p>Generating <code>Hash</code> for <code>Post</code> request</p>
  
  <pre><code>    $hashSequence = "key|txnid|amount|productinfo|firstname|email|udf1|"
                      ."udf2|udf3|udf4|udf5|udf6|udf7|udf8|udf9|udf10";
      $hashVarsSeq  = explode('|', $hashSequence);
      $hashString   = '';  
      foreach ($hashVarsSeq as $hashVar) {
          $hashString .= isset($payObject['params'][$hashVar]) ? $payObject['params'][$hashVar] : '';
          $hashString .= '|';
      }
      $hashString .= $salt;
      //generate hash
      $hash = strtolower(hash('sha512', $hashString));
  </code></pre>
  
  <p>After getting successful response generating <code>Hash</code></p>
  
  <pre><code>$retHashSeq = $salt.'|'.$status.'||||||||'.$udf3.'|'.$udf2.'|'.$udf1.'|'.$email.'|||'.$amount.'|'.$txnid.'|'.$key;
  $hash = hash("sha512", $retHashSeq);
  </code></pre>
  
  <p>But the generated <code>Hash</code> doesn't match with the returned <code>Hash</code> by the <code>PayU</code> server.
  what could be the problem?? any help would be appreciated. </p>