NetworkError: 500 Internal Server Error

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];