How to Encrypting decrypting in php

How to Encrypting decrypting  in php

Encrypt
========
$OrderNos=$rows['OrderNo'];
$OrderNo=base64_encode($OrderNos);

OR 
$kycode="3211";
$OrderNo=openssl_encrypt($OrderNos,"AES-128-ECB",$kycode);

Decrypt 
==============

$OrderNoS=$_REQUEST['OrderNo'];

$OrderNo= base64_decode($OrderNoS);

OR
$kycode="3211";

$Ordernoid=openssl_decrypt($OrderNo,"AES-128-ECB",$kycode);