Encryption and decryption using cypto

Hi All,

I want to do encryption and decryption, i am referring below document i can able to encrypt but there is no option to decrypt can any one suggest how to decrypt.

Crypto (custhelp.com)

Note: The below line simply print the cipher text with out doing any decrypt process, please check the below code block also

$cipher->decrypt();

$decrypted_text = $cipher->Text;

<?php

// All sample code is Copyright © 2006-2016, Oracle and/or its affiliates.
// All rights reserved. Sample code is provided for training purposes only.
// This sample code is provided "as is" with no warranties of any kind
// express or implied.

/***Authentication***/
require_once(get_cfg_var("doc_root") . "/ConnectPHP/Connect_init.php" );
initConnectAPI("admin", "adminpwd");

/***Use the Crypto versioned namespace***/
use RightNow\Connect\Crypto\v1_4 as Crypto;

try{
	$cipher = new Crypto\AES();  
	$cipher->Mode->ID =1; 
	$cipher->IV->Value = "1234567812345678";
	$cipher->KeySize->LookupName = "128_bits";
	$cipher->Text = "Encrypt this text with AES - MODE CBC";
	$cipher->KeyDerivative = new Crypto\CryptoKeyDerivative();
	$cipher->KeyDerivative->Mode->ID = 2;
	$cipher->KeyDerivative->Salt = new Crypto\CryptoKeyDerivativeSalt();
	$cipher->KeyDerivative->Salt->Value = "abcdefgh";
	$cipher->KeyDerivative->Password = "ABCDEFGHIJKLMNOPQRSTUVWX";
	$cipher->KeyDerivative->Iteration = 1000;
	echo "Text to be encrypted : " .$cipher->Text . "<br>";
	$cipher->encrypt();
	$encrypted_text = $cipher->EncryptedText;
	echo "Encrypted Text : " .base64_encode($encrypted_text)."<br>";

	$cipher->decrypt();
	$decrypted_text