89 lines
1.8 KiB
PHP
89 lines
1.8 KiB
PHP
<?php
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/**
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* @package FOF
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* @copyright Copyright (c)2010-2022 Nicholas K. Dionysopoulos / Akeeba Ltd
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* @license GNU General Public License version 3, or later
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*/
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namespace FOF40\Encrypt\AesAdapter;
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defined('_JEXEC') || die();
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/**
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* Abstract AES encryption class
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*/
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abstract class AbstractAdapter
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{
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/**
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* Trims or zero-pads a key / IV
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*
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* @param string $key The key or IV to treat
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* @param int $size The block size of the currently used algorithm
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*
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* @return null|string Null if $key is null, treated string of $size byte length otherwise
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*/
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public function resizeKey(string $key, int $size): ?string
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{
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if (empty($key))
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{
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return null;
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}
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$keyLength = strlen($key);
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if (function_exists('mb_strlen'))
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{
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$keyLength = mb_strlen($key, 'ASCII');
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}
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if ($keyLength === $size)
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{
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return $key;
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}
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if ($keyLength > $size)
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{
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if (function_exists('mb_substr'))
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{
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return mb_substr($key, 0, $size, 'ASCII');
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}
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return substr($key, 0, $size);
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}
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return $key . str_repeat("\0", ($size - $keyLength));
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}
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/**
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* Returns null bytes to append to the string so that it's zero padded to the specified block size
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*
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* @param string $string The binary string which will be zero padded
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* @param int $blockSize The block size
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*
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* @return string The zero bytes to append to the string to zero pad it to $blockSize
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*/
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protected function getZeroPadding(string $string, int $blockSize): string
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{
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$stringSize = strlen($string);
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if (function_exists('mb_strlen'))
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{
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$stringSize = mb_strlen($string, 'ASCII');
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}
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if ($stringSize === $blockSize)
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{
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return '';
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}
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if ($stringSize < $blockSize)
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{
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return str_repeat("\0", $blockSize - $stringSize);
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}
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$paddingBytes = $stringSize % $blockSize;
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return str_repeat("\0", $blockSize - $paddingBytes);
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}
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}
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