NetworkError: 500 Internal Server Error - php

Question

When I try to execute this file, it show me black page..
i start the firebug it shows me that NetworkError: 500 Internal Server Error
i tried to solve but cant find any problem here..
so could you help me to find what is the error or problem..??
class DesEncryptor
{
protected $_key;
protected $_iv;
protected $_blocksize = 8;
protected $_encrypt;
protected $_cipher;
/**
* Creates a symmetric Data Encryption Standard (DES) encryptor object
* with the specified key and initialization vector.
*
* #param $key
* #param $iv
* #param bool $encrypt
*/
public function __construct($key, $iv, $encrypt = true)
{
$this->_key = $key;
$this->_iv = $iv;
$this->_encrypt = $encrypt;
$this->_cipher = mcrypt_module_open(MCRYPT_DES, '', MCRYPT_MODE_CBC, '');
mcrypt_generic_init($this->_cipher, $this->_key, $this->_iv);
}
public function __destruct()
{
mcrypt_generic_deinit($this->_cipher);
mcrypt_module_close($this->_cipher);
}
/**
* Transforms the specified region of the specified byte array using PCKS7 padding.
* #param $text
* #return string
*/
public function transformFinalBlock($text)
{
if ($this->_encrypt)
{
$padding = $this->_blocksize - strlen($text) % $this->_blocksize;
$text .= str_repeat(pack('C', $padding), $padding);
}
$text = $this->transformBlock($text);
if (!$this->_encrypt)
{
$padding = array_values(unpack('C', substr($text, -1)))[0];
$text = substr($text, 0, strlen($text) - $padding);
}
return $text;
}
/**
* Transforms the specified region of the specified byte array.
* #param $text
* #return string
*/
public function transformBlock($text)
{
if ($this->_encrypt)
{
return mcrypt_generic($this->_cipher, $text);
}
else
{
return mdecrypt_generic($this->_cipher, $text);
}
}
}
When i debug with var_dump(), i found that in function transformFinalBlock
$padding = array_values(unpack('C', substr($text, -1)))[0];
it throw me error like " '[' is unexpected "
Guys, solutions plz...

Answer 1

Array de-referencing, which is what you are doing with the line $padding = array_values(unpack('C', substr($text, -1)))[0];, is only possible as of php 5.4, any prior versions, you will have to do the following to access your array:
$arr = array_values(unpack('C', substr($text, -1)));
$padding = $arr[0];