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<?php
/*
* The RandomLib library for securely generating random numbers and strings in PHP
*
* @author Anthony Ferrara <ircmaxell@ircmaxell.com>
* @copyright 2011 The Authors
* @license http://www.opensource.org/licenses/mit-license.html MIT License
* @version Build @@version@@
*/
/**
* An abstract mixer to implement a common mixing strategy
*
* PHP version 5.3
*
* @category PHPSecurityLib
* @package Random
*
* @author Anthony Ferrara <ircmaxell@ircmaxell.com>
* @copyright 2011 The Authors
* @license http://www.opensource.org/licenses/mit-license.html MIT License
*
* @version Build @@version@@
*/
namespace RandomLib;
use SecurityLib\Util;
/**
* An abstract mixer to implement a common mixing strategy
*
* @see http://tools.ietf.org/html/rfc4086#section-5.2
*
* @category PHPSecurityLib
* @package Random
*
* @author Anthony Ferrara <ircmaxell@ircmaxell.com>
*/
abstract class AbstractMixer implements \RandomLib\Mixer
{
/**
* Get the block size (the size of the individual blocks used for the mixing)
*
* @return int The block size
*/
abstract protected function getPartSize();
/**
* Mix 2 parts together using one method
*
* @param string $part1 The first part to mix
* @param string $part2 The second part to mix
*
* @return string The mixed data
*/
abstract protected function mixParts1($part1, $part2);
/**
* Mix 2 parts together using another different method
*
* @param string $part1 The first part to mix
* @param string $part2 The second part to mix
*
* @return string The mixed data
*/
abstract protected function mixParts2($part1, $part2);
/**
* Mix the provided array of strings into a single output of the same size
*
* All elements of the array should be the same size.
*
* @param array $parts The parts to be mixed
*
* @return string The mixed result
*/
public function mix(array $parts)
{
if (empty($parts)) {
return '';
}
$len = Util::safeStrlen($parts[0]);
$parts = $this->normalizeParts($parts);
$stringSize = count($parts[0]);
$partsSize = count($parts);
$result = '';
$offset = 0;
for ($i = 0; $i < $stringSize; $i++) {
$stub = $parts[$offset][$i];
for ($j = 1; $j < $partsSize; $j++) {
$newKey = $parts[($j + $offset) % $partsSize][$i];
//Alternately mix the output for each source
if ($j % 2 == 1) {
$stub ^= $this->mixParts1($stub, $newKey);
} else {
$stub ^= $this->mixParts2($stub, $newKey);
}
}
$result .= $stub;
$offset = ($offset + 1) % $partsSize;
}
return Util::safeSubstr($result, 0, $len);
}
/**
* Normalize the part array and split it block part size.
*
* This will make all parts the same length and a multiple
* of the part size
*
* @param array $parts The parts to normalize
*
* @return array The normalized and split parts
*/
protected function normalizeParts(array $parts)
{
$blockSize = $this->getPartSize();
$callback = function ($value) {
return Util::safeStrlen($value);
};
$maxSize = max(array_map($callback, $parts));
if ($maxSize % $blockSize != 0) {
$maxSize += $blockSize - ($maxSize % $blockSize);
}
foreach ($parts as &$part) {
$part = $this->str_pad($part, $maxSize, chr(0));
$part = str_split($part, $blockSize);
}
return $parts;
}
private function str_pad($string, $size, $character)
{
$start = Util::safeStrlen($string);
$inc = Util::safeStrlen($character);
for ($i = $start; $i < $size; $i+= $inc) {
$string = $string . $character;
}
return Util::safeSubstr($string, 0, $size);
}
private function str_split($string, $size)
{
$blocks = array();
$length = Util::safeStrlen($string);
$parts = ceil($length / $size);
for ($i = 0; $i < $parts; $i++) {
$blocks[] = Util::safeSubstr($string, $i * $length, $length);
}
return $blocks;
}
}
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