PTA Encryption code not working

Content

Hi Folks,

I am using below PHP code for AES 128 CBC -PTA Encryption 

PHP CODE:

<? 

$base_url = 'https://abc--tst1.custhelp.com/ci/pta/login/redirect/app/home/p_li/';
$ptaDataString ="p_userid=XYZ";
$iv = "\x0\x0\x0\x0\x0\x0\x0\x0\x0\x0\x0\x0\x0\x0\x0\x0";
$ptaDataString = openssl_encrypt($ptaDataString, 'AES-128-CBC', 'Q@$123_code*4525', $iv);// The login parameters from the external validation source must be placed in the customer portal URL and must be encoded using Base 64 encoding. 
$ptaDataString = base64_encode($ptaDataString);// In addition to using the Base 64 function, certain characters must also be replaced in the URL (+ becomes _, / becomes ~, and = becomes *).