abstract.php
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<?php
/**
* @package FrameworkOnFramework
* @subpackage utils
* @copyright Copyright (C) 2010-2016 Nicholas K. Dionysopoulos / Akeeba Ltd. All rights reserved.
* @license GNU General Public License version 2 or later; see LICENSE.txt
*/
// Protect from unauthorized access
defined('FOF_INCLUDED') or die;
/**
* Abstract AES encryption class
*/
abstract class FOFEncryptAesAbstract
{
/**
* Trims or zero-pads a key / IV
*
* @param string $key The key or IV to treat
* @param int $size The block size of the currently used algorithm
*
* @return null|string Null if $key is null, treated string of $size byte length otherwise
*/
public function resizeKey($key, $size)
{
if (empty($key))
{
return null;
}
$keyLength = strlen($key);
if (function_exists('mb_strlen'))
{
$keyLength = mb_strlen($key, 'ASCII');
}
if ($keyLength == $size)
{
return $key;
}
if ($keyLength > $size)
{
if (function_exists('mb_substr'))
{
return mb_substr($key, 0, $size, 'ASCII');
}
return substr($key, 0, $size);
}
return $key . str_repeat("\0", ($size - $keyLength));
}
/**
* Returns null bytes to append to the string so that it's zero padded to the specified block size
*
* @param string $string The binary string which will be zero padded
* @param int $blockSize The block size
*
* @return string The zero bytes to append to the string to zero pad it to $blockSize
*/
protected function getZeroPadding($string, $blockSize)
{
$stringSize = strlen($string);
if (function_exists('mb_strlen'))
{
$stringSize = mb_strlen($string, 'ASCII');
}
if ($stringSize == $blockSize)
{
return '';
}
if ($stringSize < $blockSize)
{
return str_repeat("\0", $blockSize - $stringSize);
}
$paddingBytes = $stringSize % $blockSize;
return str_repeat("\0", $blockSize - $paddingBytes);
}
}